Energy & Power

Argonne superconducting solenoid

Description: This object consists of a set of two or three nested solenoids housed within stainless steel cylindrical frames The solenoids are wound from niobium-zirconium (25%) copper coated cable. The frames have holes and slots for circulation of liquid helium within. The solenoid was designed to be used as a high-field magnet for the Argonne 10-inch liquid helium bubble chamber.; Disjoint part 1978.0469.01.2 is a retaining ring (or flange) with notches and bolt holes that was originally mounted with 2 studs inside the outer rim of one face of the cylindrical housing of the solenoid magnet (disjoint part 1978.0469.01.1). Originally, three curved strips, each covering one third of the ring circle, were attached over the ring. These strips, the screws, that presumably held them, and the two studs are not now with the ring. The three arc strips comprise disjoint part 1978.0469.01.3.; When acquired, the Argonne superconducting solenoid consisted of its 3 disjoint parts joined together as the original single object in the acquisition. For display in the "Atom Smashers" exhibit at the National Museum of American History, the ring .01.2 and its 3 associated strips .01.3 were removed to expose the coils of the solenoid assembly .01.1.; In addition, three among the set of nine spacers (irregularly shaped, thin, flat non-metallic pieces) that were mounted with an adhesive on the annular face of the solenoid frame have become separated. The three separated spacers (not numbered) have been retained in storage with the disjoint parts.; Basic Principles and History; A magnetic field is an essential feature in a bubble chamber in order to distinguish the sign of charged particles and to measure their momenta from the curvature of their bubble tracks. Charged particles moving through a magnet field are deflected in a circular path in a direction that is perpendicular to both the magnetic field lines and their direction of motion. In a chamber of a given size, higher momentum particles require correspondingly stronger magnetic fields in order to produce particle tracks of sufficiently small radius of curvature for measurement purposes.; To analyze the tracks from high-energy collisions, it is necessary to maintain the entire chamber in a strong uniform magnetic field (in excess of 20 kilogauss). Conventional (copper-coil) electromagnets that carry the high currents necessary to produce these magnetic fields can be prohibitively massive and can have attendant high cooling requirements. The discovery of superconductivity over a century ago raised the prospect of producing extremely intense electric currents – and thereby, the ability to generate correspondingly high magnetic fields using coils carrying those currents. Niobium was used in the various superconducting materials from which these coils were fabricated. Such niobium-based alloys must be cooled to cryogenic temperatures with liquid helium to become superconductive. In 1955 coils made with drawn niobium wire produced 5.3 kilogauss at a temperature of 1.2 degrees Kelvin. By the 1960’s, coils made of a compound of niobium and tin reached 40 kilogauss at 4 deg. K. The further development and application of these coils was subsequently carried out almost entirely at high-energy accelerator laboratories.; In 1963, a group at Argonne National Laboratory (ANL), together with physicists from Carnegie-Mellon University, began fabricating the first “large” superconducting solenoid magnet. Although built for use with a 10-inch diameter liquid helium bubble chamber, the Argonne superconducting solenoid was intended to test materials and fabrication techniques for building much larger superconducting magnets. The solenoid was originally composed of three concentric nested coils; in that form it produced 67 kilogauss. When used with the 10-inch bubble chamber, the innermost coil was removed. The coils are wound with several types of cable, with multiple strands in case any individual one should prove faulty. Holes and slots in the stainless steel casing, and stainless steel mesh between layers of winding, allow liquid helium to circulate through the magnet.; Success with this first large solenoid led the ANL group to use superconducting coils to provide the magnetic field for a 12-foot diameter liquid hydrogen bubble chamber. Completed in 1969, they were larger by an order of magnitude than any previous superconducting coils. Thereafter, superconducting magnets were use in other bubble chambers of the same size around the world. Among other attributes, superconducting magnets had the benefit of reducing total consumption of electrical power by more than 97%.

Date made: 1964

designer: Fields, T.H.
manufacturer: Argonne National Laboratory; AVCO Corporation

ID Number: 1978.0469.01.1
accession number: 1978.0469
catalog number: 1978.0469.01

Data Source: National Museum of American History

Alvarez proton linear accelerator

Description: Object 1978.1073.01.1 is the first seven feet of the 40-ft. long Alvarez proton linear accelerator (linac), with two of the total of 9 oscillators. The Alvarez linac became operational in 1947-48.; The accelerator assembly .01.1 consists of the following major components: horizontal cylindrical vacuum tank enclosing a cylindrical copper cavity and central beam tube, (.01.1.01), connected externally to two vertical cylindrical oscillators (.01.1.02 and 01.1.09) and their associated power systems. The vacuum chamber is open at one end to show the internal cavity and linear array of drift tubes at the center. From its open end, five feet (approx.) of top half of the vacuum chamber has been cutaway to show the outer surface of the copper cavity. As displayed in Atom Smashers exhibition, a flange-type support attached under the vacuum tank is mounted on two pyramidal-shaped, vertical supports, which rest on a low platform surface. With the exception of oscillator .01.1.09, the other components numbered from .01.1.03 to .01.1.17 are minor (e.g., bolts, pipe, cables, electrical fittings, etc. - see curator's notes for details).; History and basic principles; The linear resonance accelerator, developed by E.O. Lawrence and colleagues during the 1930’s, was one of the earliest designs for attaining high particle energy without the requirement of correspondingly high voltage. Numerous attempts to realize it were made before World War II, but all proved disappointing, largely due to the limitations of technology for generating high-frequency electric fields.; As the name implies, linear resonance accelerators are straight machines in which, as in circular cyclotrons, the accelerated motion of charged particles is synchronized with an oscillating electric field. They were first made practical by the radar technology developed during World War II. Pulsed radio transmitters of extremely high peak power at ultra-high frequency made it possible to think about adding a million volts to the energy of protons and electrons for each linear foot of the accelerator. The opportunity was recognized by many physicists developing radar in Britain and the U.S. The boldest in exploiting it was Luis W. Alvarez, one of the scientists in Lawrence’s cyclotron group at University of California, Berkeley. In the Alvarez accelerator, an intense 200 MHz electric field is produced within the copper cavity by powerful oscillators - - originally surplus radar transmitters - - for 400 microseconds, 15 times per second. Protons injected into the end of the cavity from a Van de Graaff (electrostatic) accelerator with an energy of 4 MeV are accelerated further by the oscillating electric field when crossing the gaps between the drift tubes, but are shielded by the tubes when the electric field is in the opposite, retarding, phase. Along the length of the cavity, the individual drift tubes (see object ID no. 1978.1073.01.4-.5) lengthen in proportion to the increasing particle velocity, so that the protons always take the same time to travel from gap to gap, thus remaining in step with the oscillating electric field. The proton bunches are longitudinally stable as in a synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids (see object ID no. 1978.1073.01.3.01-.03). In 1947, the linac’s 40-ft. long cavity accelerated protons to 31.5 MeV, which, until that time was the highest energy to which protons had ever been accelerated. (Berkeley’s synchrocyclotron leap-frogged the energy to 350 MeV the next year.); By 1947 the synchrotron emerged as the most practical concept for a high-energy particle accelerator, and the linac was subsequently used as the proton injector into the synchrotron. A smaller version of the Alvarez linac was used to inject 10 MeV protons into Berkeley’s “Bevatron”, a billion electron volt (BeV) synchrotron. Present injector linacs are hundreds of feet in length and produce particle beams of hundreds of MeV. For basic principles and history of synchrotrons, see McMillian synchrotron, Object ID no. N-09621.01 in the Modern Physics Collection.; Principle of strong focusing; Until 1952 designers of circular accelerators - - cyclotrons, betatrons, synchrotrons - - relied on the relatively “weak” focusing action of the magnetic field guiding ion or electron beams to hold these charged particles in stable circular orbits during acceleration. In 1952 the principle of alternating, or “strong”, focusing of particle beams was discovered at Brookhaven National Laboratory, and immediately found wide application in all types of accelerators.; Focusing forces on a particle deviating vertically are stronger the more the lines of magnetic force bulged outward, and focusing forces on a particle deviating from the orbit circle are much stronger if the magnet gap narrowed, so that the lines of magnetic force bulged inward. These two conditions, incompatible simultaneously, do not completely cancel their effects if applied successively. Thus, a sequence of magnets whose radial field gradients are directed alternatively outward and inward can have a powerful net focusing action on the particles passing through them. This approach is known as alternating-gradient focusing. The same principle applies to the action of electric fields on charged particles. After learning of the possibility and value of applying alternating-gradient focusing to proton linear accelerators, Alvarez’s group demonstrated strong radial focusing of the proton beam with electrostatic quadrupole lenses. In autumn of 1952, they immediately removed the original focusing grids and installed one such electrostatic quadrupole lens inside each drift tube (see object ID no. 1978.1073.01.5.2). The intensity of the proton beam doubled, and would have quadrupled had the insulation of the electrical leads held the required voltage. Thus the first proton linac was also the first strong-focusing accelerator. (The first accelerator to use magnetic alternating-gradient focusing was the 1 GeV synchrotron at Cornell University in 1953.) Before the prototype 32-MeV linac was shipped from Berkeley to its final location for operations at the University of Southern California, all of its drift tubes had been fitted with electrostatic strong-focusing electrodes.
Location: Currently not on view

date made: 1945-48

ID Number: 1978.1073.01.1
catalog number: 1978.1073.01.1
accession number: 1978.1073

Data Source: National Museum of American History

Section of rectangular vacuum chamber of SPEAR (Stanford Positron Electron Accelerating Ring) at SLAC

Description: Section of rectangular vacuum chamber with integral sputter ion vacuum pump. Since the complete vacuum chamber makes up a closed circular apparatus (SPEAR), object 1980.0177.03 has an arc-shaped length. Section cut away to reveal titanium sputter in vacuum pump.; SPEAR (Stanford Positron Electron Accelerating Ring) at SLAC was completed in 1972. SPEAR consists of a single ring some 80 meters in diameter, in which counter-rotating beams of electrons and positrons were circulated at energies up to 4 GeV. SPEAR was the first storage ring/colliding beam facility (collider) to provide important new discoveries in elementary particle physics, e.g., the J/psi meson that is made up of a combination of a quark and an antiquark of an entirely new kind (charm quark) and a third lepton in addition to the electron and the muon (tau lepton). Subsequently, the SPEAR facility has served as an intense x-ray source for research in physics, chemistry and biology. For detailed information, see:; http://www-ssrl.slac.stanford.edu/content/spear3/spear-history; https://www6.slac.stanford.edu/news/2011-06-02-shedding-light.aspx

Date made: 1970-1972

maker: Stanford Linear Accelerator Center

ID Number: 1980.0177.03
accession number: 1980.0177
catalog number: 1980.0177.03

Data Source: National Museum of American History

Charpak multiwire proportional chamber

Description: This object consists of an aluminum housing with two planes of stainless steel wires, rotated by 90 degrees, in a single window with four preamp units attached, one on each side. The wires are stretched between two planes of stainless steel mesh. See G. Charpak, et. al., Nucl. Instr. Meth. 62, 262 (1968) for details.; Basic Principles and History; A multiwire proportional chamber (MWPC) is constructed with alternating planes of high voltage wires (cathode) and sense wires (anode), which are at ground. All the wires are placed in a special gas environment. Spacing between planes is usually on the order of millimeters and voltage differences are typically in the kilovolt range. When a charged particle passes through the gas in the chamber, it will ionize gas molecules. The freed electrons are accelerated towards the sense wire (anode) by the electric field, ionizing more of the gas. In this way a cascade of charge develops and is deposited on the sense wires. The smaller the diameter of the sense wires, the higher the field gradient near the wire becomes. This in turn causes a larger cascade, increasing the efficiency of the chamber.; Georges Charpak built the first MWPC in 1968. Unlike earlier particle detectors, such as the bubble chamber and the first generation of spark chambers, which can record the tracks left by particles at the rate of only one or two per second, the multiwire chamber records up to one million tracks per second and sends the data directly to a computer for analysis. The price was that each wire, accumulating ions in its immediate neighborhood, must have its own electronic amplifier to record the signal; this was only practical due to the development during the previous decade of compact and inexpensive solid-state amplifiers.; In 1992 Charpak received the Nobel Prize for Physics in acknowledgment of his invention of the MWPC, an electronic particle detector that revolutionized high-energy physics experiments and has had applications in medical physics.; With the invention of the MWPC, high-energy physics entered a new era. The speed and precision of the MWPC and its subsequent generations of detectors – the drift chamber (see Charpak drift chamber, object ID no. 1977.0708.01) and the time-projection chamber – revolutionized the field of experimental particle physics. The MPWC allowed experiments to collect data at much higher collision rates and to test theories predicting the production of rare events and new massive particles. Notable examples include the discoveries of the charm quark at SLAC and Brookhaven in 1974 (Nobel Prize awarded in 1976), the W and Z bosons at CERN in 1983 (Nobel Prize awarded in 1984), and the top quark at Fermilab in 1995. For additional technical information see:; http://www.nobelprize.org/nobel_prizes/physics/laureates/1992/charpak-lecture.pdf and,; http://cds.cern.ch/record/117989/files/CERN-77-09.pdf?bcsi_scan_2687365ababd2c82=b3SiuvtOAg0NfXwMHl9pO/npSm4KAAAArlNvLw==&bcsi_scan_filename=CERN-77-09.pdf; The Modern Physics Collection also contains one of the MPWCs used in the discovery of the charm quark at Brookhaven; see Multiwire proportional chamber from J-particle experiment of S.C.C. Ting at BNL; object ID no. 1989.0050.01.1.

Date made: 1968

maker: Charpak, G.

ID Number: 1977.0708.02
catalog number: 1977.0708.02
accession number: 1977.0708

Data Source: National Museum of American History

Telegdi digital wire spark chamber spectrometer

Description: Three disjoint parts comprise the spectrometer assembly, 1977.0532.01, as follows: 01.1, the spectrometer proper - a rectangular aluminum base on which are mounted four sets of wire spark chambers (7 total), each ca. 0.4 x 0.4 x 0.03 m; 01.2, an individual core memory plane; 01.3, three light aluminum tanks that in the spectrometer assembly are placed between the 4 sets of spark chambers. The whole object includes a fraction of the associated assembly wiring.; The spectrometer proper (.01.1) consists of seven spark chambers, square planes mounted on edge on the surface of a rectangular metal base. Both the pulsed and read planes are made of 4 mil aluminum wires spaced 1 mm apart and enclosed in 1/2 mil Mylar windows. Four of the spark chambers have vertical wires and three have horizontal wires. The individual chambers are positioned on the base in order to measure the coordinates of charged particles as they trace helical orbits in a uniform perpendicular magnetic field. This data allows the energy and momentum of each particle to be determined.; Basic Principles and History; The complete Telegdi spectrometer system consists of a homogeneous magnet containing wire spark chambers with magnetic core readout. The spark chambers were covered with 0.5 mil Mylar, and a 9 to 1 neon-helium mixture flowed through them during operation. Within the spectrometer assembly, each wire chamber is connected to a corresponding memory plane containing ferrite cores. The ferrite core memory planes are located outside the spectrometer magnet in order to avoid interference from the magnetic field. Three aluminum tanks, with 5x10E-4 in. Mylar windows, serve as "helium boxes" placed between the 4 sets of spark chambers to reduce multiple scattering of charged particles (electrons) orbiting through the spectrometer.; Wire spark chambers with magnetic-core readout differ from ordinary visual spark chambers in that one of the plane electrodes (the “write plane”) is divided into wires, each of which is grounded through a ferrite core. Plug-in cables make the connection between the wire chamber and a memory plane. When a spark strikes a write wire, current flows through the core and “sets” it, thus digitizing the spark location. This information may then be transmitted conveniently to an online computer or stored on magnetic tape. For technical details see B. A. Sherwood, Phys. Rev. 156, 1475 (1967).; Between 1958 and 1965 bubble chambers dominated among particle detectors used in particle physics experiments. Bubble chambers enabled allowed photographs to be taken of the particle tracks in a three-dimensional volume and later analyzed exactly as to energy and momentum of each particle. However, accelerators soon provided such copious streams of particles that human scanning of bubble chamber photographs in search of events of interest became the most time-consuming part of the experiment.; The wire spark chamber provided electronic information of the path of a charge particle and was immediately mated with a digital computer programmed to analyze each track for distinct characteristics of interest. The Telegdi wire spark chamber spectrometer, one of the earliest applications of electronic readout spark chambers and on-line computer analysis, was developed in 1964 by V. L. Telegdi and his students at the University of Chicago to measure the energy distribution of positrons in the decay of muons. For detailed information on this experiment, see B. A. Sherwood, ibid.
Location: Currently not on view

date made: 1963-1964

maker: Telegdi, V. L.; Sherwood, B. A.; Fryberger, D.

ID Number: 1977.0532.01.1
catalog number: 1977.0532.01.1
accession number: 1977.0532

Data Source: National Museum of American History

Penning cold-cathode ion source for neon, both parts

Description: Brass Rectangular base to which is screwed cylindrical sopper discharge chamber shell with copper water cooling tubing cemented around the outside and a tantalum insert around the exit slot. Water cooled copper rod with insulated high voltage coaxial power lead fits into slot in shell with tantlum button cathode at top and bogtom of discharge chamber.; Specimen consists of used shell sandblasted clean with new tantalum cathodes and slot insert. Top cathode button the most common, so called "alternate" non water cooled arrangement. Word "neon" printed in capitals indicates shell used with neon gas. Tantalum replaceable lids lacking.; Demonstrates cold cathode heavy ion source.; ED Hudson, ML Mallory and SW Mosko, "High Performance Heavy Ion Source For Cyclotrons," "ORNL-TM-3391" (May 1971); Used with Oak Ridge 63-in. cyclotron (see object ID no. 1977.0359.41).
Location: Currently not on view

Date made: 1971

manufacturer: Oak Ridge National Laboratory

ID Number: 1977.0359.16
catalog number: 1977.0359.16
accession number: 1977.0359
collector/donor number: 76S6 type #6

Data Source: National Museum of American History

Oak Ridge 60 Inch Vertical Heavy-ion Cyclotron Dees

Description: This object is the dee assembly from the Oak Ridge 63-inch cyclotron, as adapted for the Atom Smashers exhibition at the National Museum of American History.; The object consists of copper hollow D-shaped electrodes (dees) mounted on heavy stems placed through a steel plate. The dee assembly is positioned vertically, rather than the common practice of being positioned horizontally as in most cyclotrons. The assembly is mounted on a flat painted rectangular base, constructed with unspecified construction board material. After the assembly was received at NMAH, the metal casing enclosing the dee stems was removed and discarded, and prior to being exhibited in the Atom Smashers exhibition, the stems were truncated in length by approximately two feet.; History and basic principles of the Oak Ridge 63-inch cyclotron; In 1951 the Oak Ridge National Laboratory was authorized by the Atomic Energy Commission to construct a heavy-particle cyclotron. An accelerator, designated the OREL 63-Inch Heavy-Particle Cyclotron, was then designed and built by the Electronuclear Research Division of the Laboratory. The first beam was obtained on May 20, 1952 and a productive research program was initiated shortly afterwards. The past usefulness of this cyclotron is indicated by the amount of nuclear data derived from its operation.; This cyclotron was the first built expressly to accelerate ions heavier than hydrogen and helium. Designed by Alexander Zucker, this cyclotron helped open a very active field of atomic and nuclear research, which is now pursued with much larger and costlier accelerators. It constructed was constructed to determine whether the explosion of a very powerful thermonuclear bomb might trigger a chain reaction of nitrogen nuclei, igniting the earth’s atmosphere; experiments with this cyclotron, colliding nitrogen ions with nitrogen ions, established that this fear was unwarranted.; The basic design of the 63-inch is that of a conventional, fixed-frequency cyclotron. In operation, triply charged nitrogen ions were produced by the ion source and were accelerated in a magnetic field of 15,500 gauss. The ions were then electrostatically deflected at the radius of 25.6 inches yielding an external beam of nitrogen ions with a mean energy of about 28 MeV. The accelerating system operated at a frequency of 5.1 MHz/sec and employed dee-to-earth voltages between 35 and 50 kV.; The vertical position of the dees is characteristic of cyclotrons designed at Oak Ridge. This departure from common practice at the time originally arose from parasitical use of the Calutrons, the large, ganged electromagnetic mass separators built during the Second World War to produce uranium-235 for the first atomic bombs. This and earlier Oak Ridge cyclotrons were “plugged into” Calutron magnets, in place of one of the scores of uranium isotope separation units.; Basic principles of the cyclotron; The cyclotron is the simplest of circular particle accelerators. (Go to https://www.physics.rutgers.edu/cyclotron/theory_of_oper.shtml to see a diagram of a typical cyclotron.) At its center is a vacuum chamber which is placed between the pole pieces of a large electromagnet. Within the chamber is a pair “dees” - two flat D-shaped hollow metallic shells - positioned back-to-back forming a cylindrical space, with a uniform gap between the straight sides of the two dees. The plane of the dees is parallel to the faces of the magnet pole pieces. An alternating voltage is applied across the gap between the dees, creating an associated time-varying electric field in that space.; Electrically charged particles, such as protons, alpha particles or heavier ions, are introduced into the chamber from an ion source at the center. The charged particles are constrained to travel in a circular path inside the dees in a plane perpendicular to the direction of the static uniform magnetic field produced by the electromagnet. The electric field accelerates the particles across the gap between the dees. The electric field is made to alternate with the “cyclotron period” of the particle (determined by magnetic field strength and the particle’s mass and charge). Thus, when the particles complete a semi-circle and arrive at the gap again, the electric field has reversed, so that the particles are again accelerated across the gap. Due to their increased speed in the constant magnetic field, the particles now move in a larger circle.; The increasing speed of the particles causes them to move in a larger radius with each half-rotation, resulting in a spiral path outward from the center to the outer rim of the dees. When they reach the rim the particles are pulled out by a deflecting electrode, and hit a target located at the exit point at the rim of the chamber, or leave the cyclotron through an evacuated beam tube to hit a remote target. Nuclear reactions due to the collisions of the particle beam and the target atoms will create secondary particles which may be guided outside of the cyclotron and into instruments for analysis.
Location: Currently not on view

Date made: May 20, 1952

maker: Oak Ridge National Laboratory

ID Number: 1977.0359.41.1
accession number: 1977.0359

Data Source: National Museum of American History

Charpak drift chamber connected to electronics box

Description: This object consists of two drift chamber assemblies attached to an electronic box. The two drift chamber assemblies have green plastic walls and transparent plastic windows, in metallic frames with parallel wires running horizontally in the first window and vertically in the second. They are attached to a single perforated metallic covered preamp. The latter assembly is attached on one side to rectangular, metal-enclosed, box for electronics. Wires connect the drift chamber assembly to one side of electronics box. Two high voltage cable receptacles protrude on opposite side of electronics box near top edge.; Basic Principles and History; A wire chamber is a chamber with many parallel wires, arranged as a grid and put on high voltage, with the metal casing being on ground potential. As in the Geiger counter, a particle leaves a trace of ions and electrons, which drift toward the case or the nearest wire, respectively. By marking off the wires which had a pulse of current, one can see the particle's path. If one also precisely measures the timing of the current pulses of the wires and takes into account that the ions need some time to drift to the nearest wire, one can infer the distance at which the particle passed the wire. This greatly increases the accuracy of the path reconstruction and is known as a drift chamber.; While testing their newly developed multiwire proportional chamber (see Object ID no. 1977.0708.02), Charpak and his collaborators found that the difference in arrival times of electrons at adjacent wires, they could quickly estimate just where between the two wires an ionizing particle had passed. They showed that this principle of location - - measuring the time for electrons to drift from the point where produced to a sensing wire - - could be extended from one or two millimeters to many centimeters. The essential refinement was the addition of “field shaping” wires which, by producing a uniform electric field, ensured a constant drift velocity of the electrons. In practice, the drift chamber must be preceded or followed by a counter to mark the starting time of the drifting electrons.; In 1992 Charpak received the Nobel Prize for Physics in acknowledgment of his invention of the MWPC, an electronic particle detector that revolutionized high-energy physics experiments and has had applications in medical physics.; For additional technical information, see:; http://www.nobelprize.org/nobel_prizes/physics/laureates/1992/charpak-lecture.pdf and,; http://cds.cern.ch/record/117989/files/CERN-77-09.pdf?bcsi_scan_2687365ababd2c82=b3SiuvtOAg0NfXwMHl9pO/npSm4KAAAArlNvLw==&bcsi_scan_filename=CERN-77-09.pdf
Location: Currently not on view

Date made: 1969

maker: Charpak, G.

ID Number: 1977.0708.01
catalog number: 1977.0708.01
accession number: 1977.0708

Data Source: National Museum of American History

Core memory plane for Telegdi wire spark chamber spectrometer

Description: A rectangular circuit board bearing on each side a grid of fine wires with solder joints and pin connections. From one end extend 32 black insulated wires formed into two tied bundles of 16 each, 90 inches long. The bundles are wrapped at intervals with black tape and with masking tape near the ends. The ends of the wires in each bundle emerge from their black sheaths, pass through short translucent plastic tubes, and enter a socket connector fitting. The fine wires running parallel to the length of the board have yellow insulation; the wires perpendicular to these are in eight sets on each side of the board. One set on each side has brown insulation; another, red insulation, and the remaining twelve appear as bare copper.; The wires of all 16 sets terminate in connector strips along one edge of the board. On the opposite edge is a green plastic pin socket fitting . At two corners are wide copper strips folded around on each side of the board; these are soldered to strips of different metal.; A complete spark chamber spectrometer system consists of a homogeneous magnet containing wire spark chambers with magnetic core readout. Within a spectrometer assembly, each wire chamber is connected to its corresponding core memory plane. The core planes must be located outside the spectrometer magnet. For technical details see B. A. Sherwood, Phys. Rev. 156, 1475 (1967).; For background on the Telegdi spark chamber spectrometer assembly, see description for object ID no. 1977.0532.01.1
Location: Currently not on view

date made: 1963-1964

maker: Telegdi, V. L.; Sherwood, B. A.; Fryberger, D.

ID Number: 1977.0532.01.2
catalog number: 1977.0532.01.2
accession number: 1977.0532

Data Source: National Museum of American History

Preampliier for multiwire proportional chamber from J-particle experiment of S. Ting at Brookhaven

Description: One signal amplifier on rectangular plastic circuit board. Apparently one of these preamplifiers would have been plugged into one corresponding socket of Mulitwire Proportional Chamber 1989.0050.01.1. A sticker accompanying this object reads "8 wire signals [from associated socket on chamber] get amplified .0002V to .8V" (to output to the computer). Similarly for all sockets of all four chambers in each of the two arms of the spectrometer setup at the Brookhaven Alternating Gradient Synchrotron, which was used to measure electrons and positrons resulting from decay of a hypothesized massive "J" particle.; Rectangular green plastic circuit board, with electronic components soldered on upper surface. As viewed from front of board: at left end of bottom edge are 12 contact strips, only 8 of which are connected to the circuits. Near the right end of the bottom edge are 10 such contact strips. Protruding from right edge are 10 pairs of short wires, which are inserted into a green plastic connector fitting, which has 9 contact sockets on the other side.; For background on the multiwire proportional chamber from J-particle experiment of S. Ting at Brookhaven see description for object ID no. 1989.0050.01.1
Location: Currently not on view

date made: 1972-1973

designer: Becker, Ulrich

ID Number: 1989.0050.01.2
accession number: 1989.0050
catalog number: 1989.0050.01.2

Data Source: National Museum of American History

Multiwire proportional chamber from J-particle experiment of S. Ting at Brookhaven

Description: This object consists of a rectangular frame (steel, copper) holding signal wires (gold plated wires) separated by planes of high voltage wires (Cu-Be wire). Three planes of signal wires oriented at 60 degree increments; at +80, +20 and at -40. In operation, the entire chamber was filled with gas: 80% argon to provide an ionization medium for creating a detectable electrical signal; and 20% methylal, both as a spark extinguishing and as a cleaning agent (to prevent ageing of the wires due to carbon deposits). This chamber is one of four from left arm of the spectrometer setup at the Brookhaven Alternating Gradient Synchrotron (AGS), which measured electrons and positrons resulting from decay of a hypothesized massive "J" particle.; Basic Principles and History; A multiwire proportional chamber (MWPC) is constructed with alternating planes of high voltage wires (cathode) and sense wires (anode), which are at ground. All the wires are placed in a special gas environment. Spacing between planes is usually on the order of millimeters and voltage differences are typically in the kilovolt range. When a charged particle passes through the gas in the chamber, it will ionize gas molecules. The freed electrons are accelerated towards the sense wire (anode) by the electric field, ionizing more of the gas. In this way a cascade of charge develops and is deposited on the sense wires. The smaller the diameter of the sense wires, the higher the field gradient near the wire becomes. This in turn causes a larger cascade, increasing the efficiency of the chamber.; Georges Charpak built the first MWPC in 1968. Unlike earlier particle detectors, such as the bubble chamber and the first generation of spark chambers, which can record the tracks left by particles at the rate of only one or two per second, the multiwire chamber records up to one million tracks per second and sends the data directly to a computer for analysis. In 1992 Charpak received the Nobel Prize for Physics in acknowledgment of his invention of the MWPC, an electronic particle detector that revolutionized high-energy physics experiments and has had applications in medical physics.; The MWPC in the J-particle experiment of S.C.C. Ting at Brookhaven; The 1976 Nobel Prize in physics was shared by a Massachusetts Institute of Technology physicist who used Brookhaven's Alternating Gradient Synchrotron (AGS) to discover a new particle and confirm the existence of the charmed quark. Samuel C.C. Ting was credited for finding what he called the "J" particle, the same particle as the "psi" found at nearly the same time at the Stanford Linear Accelerator Center by a group led by Burton Richter. The particle is now known as the J/psi.; Ting's experiment took advantage of the AGS's high-intensity, 30 GeV proton beams, which bombarded a stationary beryllium target to produce showers of particles. The decay modes of these particles were identified using a two-arm spectrometer detection system. J particles decay into various combinations of lighter particles; one of these combinations is an electron and a positron. A small fraction of these enter the detection system, one particle in each arm of the spectrometer. Then dipole magnets deflect them out of the plane of the intense beam and measure their momentum; Cerenkov counters measure their velocity; multi-wire proportional chambers their position; scintillator hodoscopes their moment of passage; lead-glass and lead-lucite shower counters their total energy.; In each spectrometer arm there are 4 MWPCs (Ao, A, B, C) with 2 mm wire spacing and a total of 4,000 wires on each arm. There are eleven planes of proportional wires (2 in Ao, 3 each in A, B, & C), and in A, B, & C the planes are rotated 20 degrees with respect to each other to reduce multitrack ambiguities. To ensure the chambers have 100% uniform efficiency at low voltage and a long live time in the highly radioactive environment, a special argon-methylal gas mixture at 2 deg. C was used.; The identification of the J-particle and its significance; A strong peak in electron and positron production at an energy of 3.1 billion electron volts (GeV) led Ting to suspect the presence of a new particle, the same one found by Richter. Their discoveries not only won the Nobel Prize; they also helped confirm the existence of the charmed quark -- the J/psi is composed of a charmed quark bound to its antiquark.; The J/ψ (or J/psi) is a very special particle. Its discovery was announced in 1974 independently by two groups: one lead by Samuel Ting at Brookhaven National Laboratory (BNL) in New York and the second lead by Burton Richter at Stanford Linear Accelerator Center (SLAC) in California. J/ψ is special because it established the quark model as a credible description of nature. Having been invented by Gell-Man and Zweig as a bookkeeping tool, it was not until Glashow, Iliopoulos and Maiani (GIM) that the concept of quarks as real particles was taken seriously. GIM predicted that if quarks were real, then they should come in pairs, like the up and down quarks. Candidates for the up, down, and strange were identified, but there was no partner for the strange quark. J/ψ was the key.; Like the proton or an atom, the J/ψ is a composite particle. This means that J/ψ is made of smaller, more elementary particles. Specifically, it is a bound state of one charm quark and one anti-charm quark. Since it is made of quarks, it is a “hadron“. But since it is made of exactly one quark and one antiquark, it is specifically a “meson.”; For further details, see; http://hitoshi.berkeley.edu/129A/Cahn-Goldhaber/chapter9.pdf; http://www.nobelprize.org/nobel_prizes/physics/laureates/1976/ting-lecture.pdf
Location: Currently not on view

Date made: 1972-1973

designer: Becker, Ulrich

ID Number: 1989.0050.01.1
accession number: 1989.0050
catalog number: 1989.0050.01.1

Data Source: National Museum of American History

Penning cold-cathode ion source head for carbon

Description: Copper shell with attached water cooling tubing.; Specimen heavily used, not sandblasted, shows extensive corrosion around exit slot. Word "CARBON" in capitals inscribed on outside of shell indicates its use for carbon ion beams; Demonstrates cold cathode wear.; ED Hudson, ML Mallory and SW Mosko, "High Performance Heavy Ion Source For Cyclotrons," "ORNL-TM-3391" (May 1971); Used with Oak Ridge 63-in. cyclotron (see object ID no. 1977.0359.41).
Location: Currently not on view

Date made: 1971

manufacturer: Oak Ridge National Laboratory

ID Number: 1977.0359.17
accession number: 1977.0359
catalog number: 1977.0359.17
collector/donor number: 76S6 type #7

Data Source: National Museum of American History

Sections of Magnets for Superconducting Super Collider

Description: The principal objects in accession no. 2012.0186 in the NMAH Modern Physics Collection are representations for public display of key magnet components of the Superconducting Super Collider (SSC), a large U.S. Department of Energy particle accelerator facility that was under construction from 1990 to 1993 in Ellis County, Texas, approx. 25 miles south of Dallas. The SSC was designed to produce collisions of opposing beams of protons at energies of 20 trillion electron-Volts (TeV) for experiments to advance the fundamental understanding of matter and energy. The main accelerator ring was to be located in an underground concrete tunnel with a 54-mile oval path that would encircle the City of Waxahachie. The SSC project was terminated by the U.S. Congress in October 1993, largely due to budgetary issues. The object shown in the image is a display model of a short section of a parallel pair of superconducting dipole magnets in their vacuum vessels, cut-through to show in cross-section the cold mass sub assembly (beam pipe, magnet coils, collar, yoke) and the cryogenic system conduits and insulation.; Background on SSC magnet technology; The SSC main ring design contains the two parallel proton beam pipes, each under high vacuum and encased in powerful electromagnets, in order to confine the protons to travel in their respective, opposing, paths around the ring. The two proton beams are accelerated in opposite directions over many million transits around the ring using precisely-timed energy bursts from radiofrequency cavities. When the beams achieve the desired energy, they can be brought into collision in several experimental halls located around the ring, where highly sensitive detectors capture data on the resulting showers of subatomic particles.; A sequence of electromagnets produces the necessary magnetic fields to both guide and focus the proton beams. Dipole magnets produce the field configurations that bend the beams of electrically-charged particles (protons) on their track in the beam pipe around the oval ring, and quadrupole magnets produce the field configurations that narrowly focus the beams along the central axis of the beam pipes. As designed, the SSC main ring was to use 4,326 15.8 meter long dipole magnets and 1,012 5.9 meter quadrupole magnets.; High electrical currents are required in the electromagnet coils in order to produce the strong magnetic fields that are, in turn, required to guide the proton beams in their transits at such high energies. The SSC employs superconducting technology to enable essentially unhindered current flow in the magnet coils. The coils are wound with cables that contain superconducting wire. A strand of the wire contains filaments of niobium-titanium alloy embedded in a copper matrix. For superconductivity to occur in nobium-titanium, the coils must be cooled to extremely low temperatures. Thus, a cryogenic cooling system with liquid helium and liquid nitrogen blankets the coils and iron cores of the magnets.; A similar accelerator technology is used at the Large Hadron Collider (LHC) now operating at CERN, the European Laboratory for High Energy Physics, in Geneva, Switzerland.

ID Number: 2012.0186.01
accession number: 2012.0186
catalog number: 2012.0186.01

Data Source: National Museum of American History

Nier Mass Spectrograph

Description: Background on Nier Mass Spectrograph; object id no. 1990.0446.01; catalog no. N-09567; This object consists of the following three components: ion source with oven and acceleration electrode; semicircular glass vacuum chamber; ion collector with two plates. The original device included an electromagnet, which is not part of this accession.; In 1939, as political tensions in Europe increased, American physicists learned of an astonishing discovery: the nucleus of the uranium atom can be split, causing the release of an immense amount of energy. Given the prospects of war, the discovery was just as worrying as it was intellectually exciting. Could the Germans use it to develop an atomic bomb?; The Americans realized that they had to determine whether a bomb was physically possible. Uranium consists mostly of the isotope U-238, with less than 1% of U-235. Theoreticians predicted that it was the nuclei of the rare U-235 isotope that undergo fission, the U-238 being inactive. To test this prediction, it was necessary to separate the two isotopes, but it would be difficult to do this since they are chemically identical.; Alfred Nier, a young physicist at the University of Minnesota, was one of the few people in the world with the expertise to carry out the separation. He used a physical technique that took advantage of the small difference in mass of the two isotopes. To separate and collect small quantities of them, he employed a mass spectrometer technique that he first developed starting in about 1937 for measurement of relative abundance of isotopes throughout the periodic table. (The basic principles of the mass spectrometer are described below.); As a measure of the great importance of his work, in October 1939, Nier received a letter from eminent physicist Enrico Fermi, then at Columbia University, expressing great interest in whether, and how, the separation was progressing. Motivated by such urging, by late February 1940, Nier was able to produce two tiny samples of separated U-235 and U-238, which he provided to his collaborators at Columbia University, a team headed by John R. Dunning of Columbia. The Dunning team was using the cyclotron at the University in numerous studies to follow up on the news from Europe the year before on the fission of the uranium atom. In March 1940, with the samples provided by Nier, the team used neutrons produced by a proton beam from the cyclotron to show that it was the comparatively rare uranium-235 isotope that was the most readily fissile component, and not the abundant uranium-238.; The fission prediction was verified. The Nier-Dunning group remarked, "These experiments emphasize the importance of uranium isotope separation on a larger scale for the investigation of chain reaction possibilities in uranium" (reference: A.O. Nier et. al., Phys. Rev. 57, 546 (1940)). This proof that U-235 was the fissile uranium isotope opened the way to the intense U.S. efforts under the Manhattan Project to develop an atomic bomb. (For details, see Nier’s reminiscences of mass spectrometry and The Manhattan Project at: http://pubs.acs.org/doi/pdf/10.1021/ed066p385).; The Dunning cyclotron is also in the Modern Physics Collection (object id no. 1978.1074.01; catalog no. N-09130), and it will be presented on the SI collections website in 2015. (Search for “Dunning Cyclotron” at http://collections.si.edu/search/); The Nier mass spectrometer used to collect samples of U-235 and U-238 (object id no. 1990.0446.01); Nier designed an apparatus based on the principle of the mass spectrometer, an instrument that he had been using to measure isotopic abundance ratios throughout the entire periodic table. As in most mass spectrometers of the time, his apparatus produced positive ions by the controlled bombardment of a gas (UBr˅4, generated in a tiny oven) by an electron beam. The ions were drawn from the ionizing region and moved into an analyzer, which used an electromagnet for the separation of the various masses. Usually, the ion currents of the separated masses were measured by means of an electrometer tube amplifier, but in this case the ions simply accumulated on two small metal plates set at the appropriate positions. Nier’s mass spectrometer required that the ions move in a semicircular path in a uniform magnetic field. The mass analyzer tube was accordingly mounted between the poles of an electromagnet that weighed two tons, and required a 5 kW generator with a stabilized output voltage to power it. (The magnet and generator were not collected by the Smithsonian.) The ion source oven, 180-degree analyzer tube, and isotope collection plates are seen in the photos of the Nier apparatus (see accompanying media file images for this object).; Basic principles of the mass spectrometer; When a charged particle, such as an ion, moves in a plane perpendicular to a magnetic field, it follows a circular path. The radius of the particle’s path is proportional to the product of its mass and velocity, and is inversely proportional to the product of its electrical charge and the magnetic field strength. A mass spectrometer consists of three components: an ion source, a mass analyzer, and a detector. The ion source converts a portion of the sample into ions. There is a wide variety of ionization techniques, depending on the phase (solid, liquid, gas) of the sample and the efficiency of various ionization mechanisms for the unknown species. An extraction system removes ions from the sample and gives them a selected velocity. They then pass through the magnetic field (created by an electromagnet) of the mass analyzer. For a given magnetic field strength, the differences in mass-to-charge ratio of the ions result in corresponding differences in the curvature of their circular paths through the mass analyzer. This results in a spatial sorting of the ions exiting the analyzer. The detector records either the charge induced or the current produced when an ion passes by or hits a surface, thus providing data for calculating the abundance and mass of each isotope present in the sample. For a full description with a schematic diagram of a typical mass spectrometer, go to: http://www.chemguide.co.uk/analysis/masspec/howitworks.html; The Nier sector magnet mass spectrometer (not in Smithsonian Modern Physics Collection); In 1940, during the time that Nier separated the uranium isotopes, he developed a mass spectrometer for routine isotope and gas analysis. An instrument was needed that did not use a 2-ton magnet, or required a 5 kW voltage-stabilized generator for providing the current in the magnet coils. Nier therefore developed the sector magnet spectrometer, in which a 60-degree sector magnet took the place of the much larger one needed to give a 180-degree deflection. The result was that a magnet weighing a few hundred pounds, and powered by several automobile storage batteries, took the place of the significantly larger and heavier magnet which required a multi-kW generator. Quoting Nier, “The analyzer makes use of the well-known theorem that if ions are sent into a homogeneous magnetic field between two V-shaped poles there is a focusing action, provided the source, apex of the V, and the collector lie along a straight line” (reference: A.O. Nier, Rev. Sci. Instr., 11, 212, (1940)). This design was to become the prototype for all subsequent magnetic deflection instruments, including hundreds used in the Manhattan Project.
Location: Currently not on view

Date made: ca 1940-02

associated person: Nier, Alfred O.
maker: Nier, Alfred O.

ID Number: 1990.0446.01
accession number: 1990.0446
catalog number: 1990.0446.01

Data Source: National Museum of American History

Separate display vacuum chamber for McMillan synchrotron

Description: Object N-09261.02 is a separate circular vacuum chamber with its associated accessories that were mounted on a wall in the "Atom Smashers" exhibition. This object itself is essentially identical to the vacuum chamber that is an integral subpart of the McMillan synchrotron assembly proper N-09261.01.; Object N-09261.02 consists of an assembly of the following major subparts, most of which were separated during dismantling after the Atom Smashers exhibition closed:; 8 separate circular sectors;; 2 "milk bottles" for evacuation ports ;; electron gun assembly;; target assembly with adjusting mechanism;; synchrotron light port assembly;; RF coaxial power input assembly.; (See curator's notes for details.); For background on the McMillan Synchrotron, see descrption for object ID no. N-09621.01
Location: Currently not on view

maker: McMillan, E. M.

ID Number: EM.N-09261.02
catalog number: N-09261.02
accession number: 269226

Data Source: National Museum of American History

Metal Disintegration Machining System for Three Mile Island Nuclear Reactor Vessel

Description: The metal disintegration machining (MDM) system consists of a box enclosing a cutting head assembly and an attached articulating arm assembly. The lower end of the arm is attached to the top of the cutting head assembly. The MDM system is the principal object of accession no. 2012.0171 in the NMAH Modern Physics Collection.; Background on Metal Disintegration Machining (MDM) System; Edited excerpts from "Phase 4 Status Report, Removal of Test Specimens from the TMI-2 Reactor Vessel Bottom Head, Project Summary, MPR-1195", October 1, 1990, prepared for U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research (RES). [Copy of Report in NMAH Curator's file for this accession.]; Introduction; Following the accident in March of 1979, the Three Mile Island Unit 2 (TMI-2) [nuclear] reactor vessel sustained significant internal damage. The resulting damage to the lower head and the margin to failure have been of interest to the nuclear industry. In early 1988, GPU Nuclear, the owner/operator of the TMI facility, had completed a large portion of the disassembly and defueling work inside the reactor and was preparing to remove the lower structural internals and defuel the lower head. At that point, NRC-RES initiated a project with MPR Associates to remove metallurgical specimens of the lower head and adjacent areas to determine the extent of damage to the vessel and to gain insight into the events that took place inside the vessel during the accident. The project was set up such that sampling work in the vessel would be performed by MPR after GPU Nuclear had completed defueling. Defueling ended on Jan. 30, 1990, at which time GPU Nuclear turned control of the reactor vessel over to MPR.; Techniques and Special Tooling; [In order to satisfy NRC-RES, GPUN and MPR project objectives], electrical discharge machining was selected for vessel sampling. The cutting technique used is referred to as metal disintegration machining (MDM). Both the MDM process and the more commonly used electric discharge machining (EDM) remove conductive material by melting away small bits of material using an electric arc between an electrode and the work piece. EDM makes and breaks electrical arcs by switching the electrical current on and off using transistors. MDM makes and breaks electrical arcs by moving the electrode into and away from the work material. MDM was used in the project due to the high conductivity of the reactor vessel water. The MDM cutting head has two U-shaped graphite electrodes to cut the triangular [boat-shaped] samples. The electrodes are attached to hydraulic cylinders and slide on tracks mounted at angles to provide a sample with an included angle of about 60 degrees. The electrodes are consumable and were designed to be replaced after each sample cut. PCI Energy Services, under contract to MPR, developed and tested the MDM cutting equipment. The MDM head was positioned at the vessel sample locations with a delivery system consisting of several long pipe sections and a hinged arm which articulated the MDM cutting head to the desired angle for sampling the vessel head. The MDM cutting system was used to cut samples both in open areas of the vessel and at incore penetrations.; For details on the MDM cutting system and associated equipment, and for a full description of the development and qualification program, refer to the above Report document in the Curator's file for this acquisition.

date made: 1988-1989

maker: PCI Energy Services, Inc.

ID Number: 2012.0171.01
accession number: 2012.0171
catalog number: 2012.0171.01

Data Source: National Museum of American History

Sample of Plutonium-239

Description: The discovery of nuclear fission in uranium, announced in 1939, allowed physicists to advance with confidence in the project of creating "trans-uranic" elements - artificial ones that would lie in the periodic table beyond uranium, the last and heaviest nucleus known in nature. The technique was simply to bombard uranium with neutrons. Some of the uranium nuclei would undergo fission, newly understood phenomenon, and split violently into two pieces. In other cases, however, a uranium-238 nucleus (atomic number 92) would quietly absorb a neutron, becoming a nucleus of uranium-239, which in turn would soon give off a beta-particle and become what is now called neptunium-239 (atomic number 93). After another beta decay it would become Element 94 (now plutonium-239); By the end of 1940, theoretical physicists had predicted that this last substance, like uranium, would undergo fission, and therefore might be used to make a nuclear reactor or bomb. Enrico Fermi asked Emilio Segre to use the powerful new 60-inch cyclotron at the University of California at Berkeley to bombard uranium with slow neutrons and create enough plutonium-239 to test it for fission. Segre teamed up with Glenn T. Seaborg, Joseph W. Kennedy, and Arthur C. Wahl in January 1941 and set to work.; They carried out the initial bombardment on March 3-6, then, using careful chemical techniques, isolated the tiny amount (half a microgram) of plutonium generated. They put it on a platinum disc, called "Sample A," and on March 28 bombarded it with slow neutrons to test for fission. As expected, it proved to be fissionable - even more than U-235. To allow for more accurate measurements, they purified Sample A and deposited it on another platinum disc, forming the "Sample B" here preserved. Measurements taken with it were reported in a paper submitted to the Physical Review on May 29, 1941, but kept secret until 1946. (The card in the lid of the box bears notes from a couple of months later.); After the summer of 1941, this particular sample was put away and almost forgotten, but the research that began with it took off in a big way. Crash programs for the production and purification of plutonium began at Berkeley and Chicago, reactors to make plutonium were built at Hanford, Washington, and by 1945 the Manhattan Project had designed and built a plutonium atomic bomb. The first one was tested on July 16, 1945 in the world's first nuclear explosion, and the next was used in earnest over Nagasaki. (The Hiroshima bomb used U-235.); Why is our plutonium sample in a cigar box? G.N. Lewis, a Berkeley chemist, was a great cigar smoker, and Seaborg, his assistant, made it a habit to grab his boxes as they became empty, to use for storing things. In this case, it was no doubt important to keep the plutonium undisturbed and uncontaminated, on the one hand, but also, on the other hand, to make it possible for its weak radiations to pass directly into instruments - not through the wall of some closed container. Such considerations, combined probably with an awareness of the historic importance of the sample, brought about the storage arrangement we see.
Location: Currently not on view

Date made: 1941-05-21
Associated Date: 1941-05-29

referenced: Segre, Emilio; Seaborg, Glenn T.; Kennedy, Joseph W.; Wahl, Arthur C.; Lewis, G. N.; University of California, Berkeley
maker: Segre, Emilio; Seaborg, Glenn

ID Number: EM.N-09384
catalog number: N-09384
accession number: 272669

Data Source: National Museum of American History

First betatron of Donald Kerst, 1940

Description: Object N-08216 is the assembly of the first Kerst Betatron as it appeared in the Atom Smashers exhibition at the NMAH. mounted horizontally, a toroidal vacuum chamber made of white ceramic with two cylindrical ports, each joined to fused-on glass extensions; circular magnet coils mounted above and below plane of vacuum chamber; rectangular laminated iron yoke surrounding the coils on top, bottom and two sides; enclosing the yoke, a rectangular metal frame of four horizontal angle strips joined by four welded vertical straps, two on each side, and by four bolts, two on each end. Between the yoke laminations and each coil is a thin sheet of slightly flexible, warped, black material, like plastic or impregnated cardboard; each is in two pieces to fit around the central axis. Two circular gray plates are positioned at the top and bottom of the vacuum chamber, separating it from the upper and lower coils, respectively.; It is presumed that the left-hand cylindrical port contains the electron source, and the right-hand port contains the beam of x-rays from the internal target. Wires protrude from both cylindrical ports.; History and basic principles; Among the many investigators who attempted to accelerate electrons by magnetic induction, none were successful until Donald Kerst produced 2.3-MeV electrons in a betatron at the University of Illinois in 1940. He later constructed a number of betatrons of successively higher energies, culminating in the 300-MeV betatron at the University of Illinois. Kerst’s success was due to a very careful theoretical analysis of the orbit dynamics in accelerators (including a study of the requirements for injection); to a preliminary analysis of all conceivable effects relevant to the operation of a betatron; and to a careful and detailed design of the magnet structure, vacuum system, and power supply. This was the first new accelerator to be constructed on the basis of a careful scientific analysis and a completely engineered design. Its success represented a turning point in the technology of particle accelerators from cut and try methods to scientifically engineered designs. All later accelerators, including the newest high energy synchrotrons, have been influenced by this early work of Kerst. It is only in the light of these later developments that we see the importance of the betatron not merely as a valuable instrument in itself but as a milestone in the development of particle accelerators generally. For example, the radial and vertical oscillations of the beam in all particle accelerators are now universally called betatron oscillations after the pioneering work of Kerst and Robert Serber, who together in 1941 published the first theoretical analysis of such oscillations as they occur in the betatron.; The betatron was quickly put to use in industry, medicine, and nuclear physics research. It was the first accelerator to provide gamma rays for photo-nuclear studies. In the late 1940s and early 1950s the betatron was used for much of the experimental research on photo disintegration of the deuteron, on photo-nuclear reactions (including the discovery of the giant dipole resonances), and important early work on nuclear structure from electron scattering. Of great importance was the pioneering use of megavolt electron beams for the production of energetic X rays for the therapeutic treatment of cancer. His fascinating depiction of this treatment included a description of the first use of phantoms and the intense activity precipitated by a student afflicted with brain tumor, heroic efforts that achieved much, but were unable to save the student. Kerst took a one-year leave of absence from the University of Illinois (1940-41), designed a 20-MeV betatron and a 100-MeV betatron working with the engineering staff at General Electric. He oversaw the construction and operation of the 20-MeV betatron, which he brought back to Urbana. During World War II days, Kerst built a 4-MeV portable betatron for inspecting bomb duds in situ and, most importantly, built a 20-MeV betatron at Los Alamos for study of bomb assembly implosions. His work was described in the official history of Los Alamos as: “The technical achievements are amongst the most impressive at Los Alamos.” After World War II Kerst built a 300-MeV betatron at the University of Illinois that was brought into operation in 1950 and provided a facility for studying high energy physics until it was superseded by synchrotrons and then by electron linacs.; (Above text excerpted from Donald William Kerst, 1911—1993, a Biographical Memoir by Andrew M. Sessler and Keith R. Symon, Copyright 1997, National Academies Press, Washington DC.); It is no accident that the magnetic induction accelerator was so late to be realized. The concept had been advanced repeatedly in the preceding twenty years, but the problems of establishing and maintaining a particle beam were far greater than those encountered with several other accelerator types that were reduced to practice in the 1930’s.; Electrons, due to their relatively small mass, are much more “skittish” than the much more massive protons, and in the betatron must make a thousand times more circuits to reach the same energy as protons accelerated in a cyclotron. Where the cyclotron runs continuously, allowing the protons to find their own orbit, the betatron is pulsed: electrons must be injected at the right velocity to be captured into stable orbits, and held in them by a balance between the magnetic fields responsible for their acceleration and their orbit guidance, respectively. Kerst’s success depended decisively upon close mathematical analysis of these orbits, especially those immediately after injection into the vacuum chamber. This analysis was performed in collaboration with theoretical physicist, Robert Serber.; The principle of operation of the betatron is similar to that of a high voltage transformer. Alternating currents in the upper coils produce an increasing magnetic field, thus inducing an electromotive force around the electron’s circular orbit. This force, which Kerst calculated to be only 17 volts maximum acts on the electrons during each of their 200,000 circuits of the vacuum chamber, imparting a total energy of over two million electron volts (MeV).; The electrons are introduced into the vacuum chamber by an injector; they are not brought out of the vacuum chamber, but strike an internal target, converting their energy into x-rays which emerge through a second port.; Kerst, like E.O. Lawrence at the University of California, Berkeley, saw no intrinsic limits to his device. From the moment Kerst’s first device operated successfully in July 1940, he and his University looked forward to one more powerful (300 MeV) even than the cyclotrons being developed at Berkeley. Begun in 1945, immediately after World War II, with a special appropriation from the Illinois State Legislature, it was soon to be outmoded by newer methods of particle acceleration (e.g., the synchrotron).
Location: Currently not on view

date made: early 1940's

maker: Kerst, Donald

ID Number: EM.N-08216
accession number: 233629

Data Source: National Museum of American History

Control Console for 105-D Hanford plutonium production reactor

Description: Background on Control Console for 105-D Plutonium Production Reactor; object cat. no. 1993.0138.02; The Manhattan Project, the scientific and military undertaking to develop the atomic bomb, was formally launched by the U.S. government in September 1942. For a short history of it, go to; http://www.atomicarchive.com/History/mp/index.shtml; Author Richard Rhodes has written a highly-regarded comprehensive history of the atomic bomb, including the story of the Hanford reactors, rich in human, political and scientific detail: Rhodes, Richard. 1986. The Making of the Atomic Bomb. Simon and Schuster.; As part of the Manhattan Project, plutonium production reactors were constructed at Oak Ridge, Tennessee and then at Hanford, Washington. The first was the experimental X-10 Graphite Reactor built at Oak Ridge; it went online in 1943 and served as the prototype for the series of reactors at Hanford. The 100 Area is the part of the Hanford Site located along the banks of the Columbia River. It is where the nine reactors built from 1943 through 1965 are found. They were constructed next to the river because they needed plenty of hydroelectric power and cooling water during operation. The first three of these, 105-B, 105-D, and 105-F, were built simultaneously about six miles apart, starting in October 1943. The first completed, the 105-B Reactor, started operations in September 1944, and produced the fissile material for the two plutonium bombs used during World War II, the “Trinity” test bomb and the bomb dropped on Nagasaki. This 105-B Reactor, the world’s first full-scale nuclear reactor, has been designated a U.S. National Historic Landmark, and is also part of the new Manhattan Project National Park. For a detailed description of the construction and operation of this reactor, see the following document:; Historic American Engineering Record; Hanford Cultural and Historical Resources Program,; B REACTOR HANFORD SITE, HAER No. WA. 164, DOE/RL-2001-16; (pdf file posted online at http:/www.b-reactor.org/history.htm); The world’s second full-scale nuclear reactor was the 105-D. It began operating in December of 1944, ran through June of 1967, and was ultimately “cocooned” in 2004. (Cocooning is a process by which the reactor core is encased in a concrete shell for 75 years to allow residual radioactivity to decay away. This cocoon is designed to prevent any radiation or contamination left over from the nuclear operations from escaping to the environment.); The control room of each of Hanford’s nuclear reactors, such as the 105-D, received the information necessary for monitoring and controlling the plant and contained the facilities for operating it. These first generation control rooms consisted almost entirely of panel instrumentation with fixed, discrete components such as switches, indicator lights, strip chart recorders, analog gauges, and annunciator windows. The early Hanford reactors were equipped with various safety and control instruments that measured temperature, pressure, moisture, neutron flux, and radioactivity levels. For a description of these measurements, see pp. 51-55 in the HAER document referenced above. Two measurement examples follow.; 1) Moisture content in the circulating helium atmosphere surrounding the reactor. “Water was chosen as the coolant for the Hanford piles [reactors] . . . because it was available in large quantities, had a high heat-transfer coefficient, and was well understood among engineers. The decision to use water was not an easy one, because although water is an effective coolant, it is also an oxidizer of uranium and, in a graphite-moderated pile, an effective poison for the chain reaction” (ibid, p. 42). The largest component of air, nitrogen, is a relatively good absorber of neutrons. “Any air within the pile, therefore, would serve to poison the chain reaction. Another problem associated with air in the pile is argon gas. Although it makes up only a tiny portion of a given volume of air (about 0.9 percent), argon readily becomes radioactive when exposed to the intense neutron flux (flow rate or density) of a pile (more so than the all the other gases in air combined). It was almost impossible to make the pile absolutely gas-tight, so any air within the pile could leak into the surrounding work areas, where the radioactive argon gas could present a hazard to the workers. To eliminate both these problems, the pile’s atmosphere was replaced with circulating helium gas. Helium absorbs no neutrons within the pile and is the one element in which radioactivity cannot be induced by neutron bombardment. There were still more advantages to a helium atmosphere. Helium has a fairly high thermal conductivity (five or six times that of air), meaning that it would aid in the transfer of heat from the pile’s graphite shields and control-rod passages to the 2,004 cooling tubes. Helium is inert, which made it easier to detect water leaks within the pile by sampling the gas as it circulated out of the pile, at which point the helium gas could then be dried and purified” (ibid p.36). “The circulating helium was tested for moisture content in order to reveal any leaks within the pile. Samples could be drawn from the main gas duct, or from 10 sampling tubes that penetrated the rear shielding into the 4 in. gas plenum” (ibid p. 37).; 2) Neutron flux levels. “The primary measure of the pile’s chain reaction was the neutron density, or flux, within the pile. One problem with the design of the instrumentation that measured this reactivity was the incredible range of neutron density involved. . . . When it was running at full power, the neutron flux was 100 billion times greater than when it was shut down or running at very low power. To handle this range, two different sets of neutron monitors were needed. The high-level flux was measured by four ionization chambers installed in different tunnels under the pile. . . . The very small current developed by these chambers was measured by picoammeters located in the control room. At the time, these Beckman meters (named after the company that made them) were called micro-microammeters, and were state of the art” (ibid p.53). “When the pile was shut down or running at very low power levels, the low-level neutron fluxmonitor system, or subcritical monitor, would measure its reactivity. Its primary use was to determine when the pile achieved criticality and the rate of rise of power level. The galvanometer system consisted of one ionization chamber under the pile connected to two galvanometers in series. One galvanometer provided a signal (deflection) proportional to the neutron flux, while the other registered the deviation from a preset level. In this way, the system could show small changes in the neutron flux. This system also included shunts and potentiometers at the control room console to compensate for range changes” (ibid, p. 54).; The control console, the separate water temperature control panel, and some related artifacts from the 105-D Reactor are in the Smithsonian’s Modern Physics Collection (accession no. 1993.0138). The control console closely resembles the console at Oak Ridge for the X-10 Reactor. It consists of a wooden cabinet with black metal instrument panels occupying the upper part and the right side of the front (see accompanying media images). A console projecting below the center and left portion contains three small inclined control panels designed for a seated operator. Indicators include two chart recorders (one is "Differential Pwr. Recorder"), two translucent glass galvanometer scales (presumably for the neutron flux monitoring function quoted above), and gauges for fuel rods. There are also numerous switches and knobs for equipment such as control rods, pumps, and bypasses. [See curator's file for details on location, dimensions, markings and condition of each section (including details on gauges, recorders, switches, lights, buttons, etc.)].; Brief description of nuclear fission using slow neutrons; Several heavy elements, such as uranium, thorium, and plutonium, undergo both spontaneous fission, a form of radioactive decay, and induced fission, a form of nuclear reaction. Neutrons, because they have no electrical charge, are not repelled by the positively charged atomic nucleus of an atom. Slow neutrons have a greater probability than fast neutrons of being absorbed in the nucleus of certain isotopes. Elemental isotopes that undergo induced fission when struck by a free neutron of any energy are called fissionable; isotopes that undergo fission when struck by a “thermal,” slow moving, neutron are also called fissile. A few particularly fissile isotopes, notably U-233, U-235 and Pu-239, can be used as nuclear fuels because under certain conditions assemblies of these isotopes can sustain a chain reaction through the release of additional neutrons among their fission products. This makes possible a self-sustaining nuclear chain reaction that releases energy at a controlled rate in a nuclear reactor or at a very rapid uncontrolled rate in a nuclear weapon. Although Pu-239 is exceedingly rare in nature, it was discovered that U-238 atoms could be transmuted to Pu-239 (capture of extra neutrons by U-238 to form U-239, which then undergoes a series of decays to form Pu-239). The required quantities of Pu-239 were produced in the nuclear reactors at Hanford, in which U-238 atoms absorbed neutrons that had been emitted from U-235 atoms undergoing fission. The plutonium so produced was then chemically separated from the uranium in dedicated separation facilities.; For the basic concepts of nuclear fission, chain reactions, critical mass, fission of uranium and plutonium isotopes, and the basic principles used for atomic bombs developed in the Manhattan Project, go to: http://www.atomicarchive.com/Fission/Fission1.shtml

ID Number: 1993.0138.02
catalog number: 1993.0138.02
accession number: 1993.0138

Data Source: National Museum of American History

Bose-Einstein Condensation Apparatus

Description: The apparatus that was used to produce the first Bose-Einstein Condensate (BEC) observed in a gas of atoms; In 1995, a group of physicists led by Eric A. Cornell and Carl E. Wieman produced the first BEC in a gas of 2000 rubidium atoms at the NIST–JILA laboratory at the University of Colorado at Boulder. Just about four months later, a group led by Wolfgang Ketterle independently produced a BEC with about 200,000 sodium atoms. Cornell, Wieman and Ketterle were awarded the 2001 Nobel Prize in Physics for their accomplishments.; The Cornell and Wieman BEC apparatus consisted of an atomic trap that cooled atoms by means of two different mechanisms. First, six laser beams cooled the atoms, initially at room temperature, while confining them near the center of an evacuated glass box. Next, the laser beams were turned off, and magnetic coils were energized. Current flowing in through the coils generated a magnetic field that further confined most of the atoms while allowing the more energetic ones to escape. Thus, the average energy of the remaining atoms decreases, making the sample colder and even more closely confined to the center of then trap. Ultimately, many of the atoms attain the lowest possible energy state allowed by quantum mechanics, and become a single entity – a BEC. Other research groups are now using BEC principles for investigations in the field of atom quantum optics, including quantum information processing and development of the atomic analogue of the laser.; The core components of the Cornell-Wieman BEC apparatus are in the Modern Physics Collection at the Smithsonian Institution’s National Museum of American History, in accession no. 1998.0213.; Background on the Bose-Einstein Condensate (BEC) phenomenon; [Adapted from “The Bose-Einstein Condensate,” E.A. Cornell and C.E. Wieman in Scientific American, March, 1998, pp 40-45; and from “Very Cold Indeed: The Nanokelvin Physics of Bose-Einstein Condensation,” Journal of Research of the National Institute of Standards and Technology, V. 101, Jul.–Aug. 1996, p. 419]; In June 1995, a team of scientists succeeded in cooling a gas of 2,000 rubidium atoms to a temperature less than 100 billionths of a degree above absolute zero, causing the atoms to lose for a full ten seconds their individual identities and behave as though they were a single “superatom.” That is, the atoms’ physical properties, such as their motions, became identical to one another. This Bose-Einstein Condensate (BEC), the first observed in a gas, can be thought of as the matter counterpart of the laser – except that in the BEC it is atoms, rather than photons of light, that behave in perfect unison (all going in the same direction with the same energy).; The BEC offers a macroscopic window into the strange world of quantum mechanics, the theory of matter based on the observation that elementary particles, such as electrons, have wave properties. Quantum mechanics uses these wavelike properties to describe the structure and interactions of matter. In ordinary macroscopic matter, the incoherent contributions of the large number of constituent atoms obscure the wave nature of quantum mechanics. But as atoms get colder, they start to behave more like waves and less like particles. Cool a cloud of identical atoms so cold that the wave of each atom starts to overlap with the wave of its neighbor atom, and all of a sudden one creates a BEC. In a BEC, the wave nature of each atom is precisely in phase with that of every other. Quantum mechanical waves extend across the collection of atoms, an image of which can be observed with the naked eye.; Some five decades earlier, physicists had realized that the BEC concept could explain superfluidity in liquid helium, which occurs at much higher temperatures than gaseous Bose-Einstein condensation. (Superfluidity is a state of matter in which the matter behaves like a fluid without viscosity and with extremely high thermal conductivity.) When it passes below a critical temperature, liquid helium makes the transition from an ordinary liquid to a superfluid and starts to behave like a quantum fluid. But the helium atoms in the liquid state interact quite strongly, and the system is difficult to understand on an elementary level. Thus, physicists had been pushing for many years to observe Bose-Einstein condensation in a system closer to the gaseous state.; Brief description of fermions and bosons, and Bose-Einstein statistics; All elementary particles, and even composite particles such as atoms, can be divided into bosons and fermions. [The spin of an elementary particle is a truly intrinsic physical property, akin to the particle's electric charge and rest mass, and is expressed as a spin quantum number.] Bosons are particles that have integer spin; 0, 1, 2, 3, and so on (in units of reduced Plank constant, h/(2π)). Fermions are particles that have half-integer spin: 1/2, 3/2, 5/2, and so on, in the same units. Examples of bosons are particles that transmit interactions (i.e., force carriers), such as photons (electromagnetic force), and a large portion of the atoms of individual chemical elements. Examples of fermions are particles that are the elementary building blocks of matter: electrons, protons, neutrons, and the quarks inside protons and neutrons. All atoms are composed of fermions, but if the atom consists of an even number of fermions, it will be a composite particle with integer spin, which is a boson. The new statistics (see below) was first studied in 1924 by Satyendra Nath Bose, so physicists call particles for which only symmetrical states occur in nature bosons. [According to the Oxford English Dictionary, the term “boson” was introduced by physicist Paul Dirac in 1947; P.A.M. Dirac Princ. Quantum Mech, (ed. 3) ix. 210.]; Fermions, the particles with half-integer spin obey Fermi-Dirac statistics. Accordingly, they occupy anti-symmetric quantum states; this property forbids fermions from sharing quantum states – a restriction known as the Pauli Exclusion Principle. Bosons, the particles with integer spin, on the other hand, obey Bose-Einstein statistics (see below). Accordingly, they occupy symmetric quantum states; this property allows bosons to share quantum states. Thus, the latter property allows a collection of identical atoms that are bosons to be cooled to the same quantum state, which is termed a BEC.; Satyendra Nath Bose (1 January 1894 - 4 February 1974) was an Indian mathematician and physicist, best known for his work on quantum mechanics in the early 1920s, which provided the foundation for Bose–Einstein statistics and the theory of the BEC. Specifically, Bose developed a statistical model, based on a counting method that assumed that light could be understood as a gas of indistinguishable quanta or particles. Bose is honored as the namesake of such a particle, a boson; Albert Einstein (14 March 1879 - 18 April 1955) was a renowned, German-born theoretical physicist who developed the theories of special and general relativity, effecting a revolution in physics. In 1924, Einstein received a paper from Bose describing his statistical model. Einstein noted that Bose's statistics also applied to some types of atoms, as well as to the proposed indistinguishable light particles, and submitted his translation of Bose's paper for publication in the Zeitschrift für Physik. Einstein also published his own articles describing the Bose statistical model and its implications, among them the condensate phenomenon that derives from the fact that the number of quantum states available for a collection of bosons at very low energy becomes exceedingly small. With less and less room for all of the particles when the temperature is decreased, they accumulate (condense) in the lowest possible (ground) energy state, as a BEC. [According to the Oxford English Dictionary, the term “Bose-Einstein Condensation” was first used in a 1938 scientific publication; Physical Review, 54 947.] Bose-Einstein statistics are now used to describe the behaviors of any assembly of bosons.
Location: Currently not on view

ID Number: 1998.0213.01.01
catalog number: 1998.0213.01.01
accession number: 1998.0213

Data Source: National Museum of American History

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Argonne superconducting solenoid

Alvarez proton linear accelerator

Section of rectangular vacuum chamber of SPEAR (Stanford Positron Electron Accelerating Ring) at SLAC

Charpak multiwire proportional chamber

Telegdi digital wire spark chamber spectrometer

Penning cold-cathode ion source for neon, both parts

Oak Ridge 60 Inch Vertical Heavy-ion Cyclotron Dees

Charpak drift chamber connected to electronics box

Core memory plane for Telegdi wire spark chamber spectrometer

Preampliier for multiwire proportional chamber from J-particle experiment of S. Ting at Brookhaven

Multiwire proportional chamber from J-particle experiment of S. Ting at Brookhaven

Penning cold-cathode ion source head for carbon

Sections of Magnets for Superconducting Super Collider

Nier Mass Spectrograph

Separate display vacuum chamber for McMillan synchrotron

Metal Disintegration Machining System for Three Mile Island Nuclear Reactor Vessel

Sample of Plutonium-239

First betatron of Donald Kerst, 1940

Control Console for 105-D Hanford plutonium production reactor

Bose-Einstein Condensation Apparatus

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