High Energy Physics Laboratory Research Articles

Status of Musl-2, the Second Microtron Using a Superconducting Linac

A second racetrack microtron, MUSL-2, is being assembled in the area previously occupied by the 300 MeV betatron. It uses a Van de Graaff to inject electrons at about 2 MeV, a 6 meter, 1.3 GHz superconducting linac made for us at the Stanford High Energy Physics Laboratory as the accelerating section and the magnets from MUSL-1 for recirculation <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> . A digital control console has been installed to operate the linac and the injection and recirculation systems. The CTI 1400 helium liquefier together with the low pressure heat exchanger from MUSL-1 maintains the linac at about 2 K. Beams of 10 microamperes with energies up to 14 MeV with a resolution of 0.2% are being used for nuclear experiments. Continuous beams up to 72 MeV will be available after the installation of the 6 pass system is completed. Present plans for moving toward higher energies involve the use of MUSL-2 to inject electrons with energies up to 72 MeV into a second superconducting linac in a microtron operating at v=1. With return orbits separated by 7.35 cm relatively small magnets in the second system can accommodate 18 additional passes. At 12 MeV per pass electrons would reach a final energy of 288 MeV.

An automatic film scanner (KAMA) utilizing a new type CRT with double deflection scheme

A newly developed high precision CRT with a double deflection scheme is utilized for a flying spot generator in the KAMA system, an automatic film measuring apparatus at KEK, National Laboratory for High Energy Physics. A concept of man-machine communication is introduced by using an optical and a graphical display. The spot size of the CRT presently used is about 25 μm equally over the area of about 80 × 80 mm 2 on the screen of the 9″ tube. The spot is reduced to about 12.5 μm on the film plane by the demagnification by a factor 2. The reproducibility of a point digitization is within less than 1 μm, and the track reconstruction residuals peak at 4.5 μm on the film for 4.5 GeV/ c π − tracks. Event measurements have been carried out under the vertex guidance method. The failure rate of the KAMA automatic measurements in TVGP-processing is less than 10% for the 4-pronged events from the 4.5 GeV/ c π −p SLAC-LBL 82″ hydrogen bubble chamber film. The general lay-out and performance of the KAMA, an easy-handling high-precision CRT film scanner are described.

フォトン・ファクトリーにおけるデータ処理

The on-line data processing systems in high energy physics laboratories in Japan, America and Europe are described. The computer system of these institutes is a complex system of central (large) computers and terminal (mini) computers. A terminal computer works mainly for data taking from detector and monitoring of data. Data taking is performed through a CAMAC system. CAMAC is explained shortly. The matter for preparation at a Photon Factory data processing system are also stated.

Analog Monte Carlo studies of electron−photon cascades and the resultant production and transport of photoneutrons in finite three−dimensional systems

A major computer program has been written to perform Monte Carlo studies of electron−photon cascades and the resultant production and transport of photoneutrons in finite three−dimensional systems. It is programmed in FORTRAN and is explicitly designed to be easily used and extended to yield a fast, adaptable, and versatile computer program that has wide application to problems in solid−state, nuclear, and reactor physics. It combines a simple but accurate procedure for sampling from an arbitrary differential probability distribution with efficient cross−section representations to perform complicated single−particle of many−particle calculations. The calculations of Alsmiller and Moran at ORNL and the experiments of Barber and George at the Stanford High Energy Physics Laboratory have been compared with results of the new computer code. The comparisons indicate that the results of the new Monte Carlo studies are in good agreement with the ORNL calculations of the photoneutron yield in cylindrical targets of Cu, Ta, Pb, and U for a wide variety and 100 MeV. The comparisons also yield good agreement with the Stanford experiments of the photoneutron yield in rectangular targets of Cu, Ta, experiments of the photoneutron yield in rectangular targets of Cu, Ta, experiments of the photoneutron yield in rectangular targets of Cu, Ta, Pb, and U for a wide variety of target thicknesses for incident electron energies ranging from 10 to 34 MeV. A series of Rensselaer Polytechnic Institute LINAC ’’bare’’ target experiments have been analyzed with the Monte Carlo program. The computational studies and the experimental results are in good agreement. In particular, there is excellent agreement on the angular distributions of photoneutrons from the tree spherical Pb targets as measured using foil detectors. the calculated results predicted quite faithfully the observed improvement in the angular distributions as the design of the spherical Pb target was modified to obtain a more isotropic distribution.

Perturbations in angular correlations as an interference phenomenon: H. J. Leisi. Laboratory for High Energy Physics, Swiss Federal Institute of Technology Zurich, c/o SIN, 5234 Villigen, Switzerland

Perturbations in angular correlations as an interference phenomenon: H. J. Leisi. Laboratory for High Energy Physics, Swiss Federal Institute of Technology Zurich, c/o SIN, 5234 Villigen, Switzerland

Superconducting Proton Synchrotron

Pulsed superconducting magnet is becoming more attractive for future accelerators and for improving existing ones to realize higher accelerating energy. The technique being now developed in the high energy physics laboratories is also generally very important from the standpoint of A. C. electrotechnical application of superconductors, i.e., practical problems of A. C. loss, wire technique, winding technique, cooling and cryogenic problems, radiation problem, etc.The requirements and engineering problems for development of a superconducting synchrotron magnet are discussed. The project at CERN is presented. The state of the art and experience with various conductors and winding method in several laboratories are briefly reviewed.

High energy physics in the UK—1968

Annual reports for the year 1968 have recently been published from the SRC high energy physics laboratories—Rutherford and Daresbury. These make encouraging reading for anyone interested in the wellbeing of physics at British universities.

Tunnel Dug at Stanford For Superconducting Linac

A tunnel 183 meters long and 4 meters in diameter has been dug for the 152-meter superconducting niobium linear accelerator to be built underneath the Stanford High Energy Physics Laboratory (PHYSICS TODAY, Jan. 1966, page 96). The 15 000-liter, 300-watt superfluid helium refrigerator is being installed, and the first 6.1-meter aluminum dewar sections have been delivered. William M. Fairbank and H. Alan Schwettman, heading the design team, hope to have the linac in operation by 1971.

995. High vacuum slide valve: M B Bronfin and V A Marichev,Zavodsk Lab, 34 (1), 1968, 116–117 ( in Russian)

A remote pressure measurement system suitable for ultra-high vacuum in a very severe noise environment, such as found in high energy accelerators, is reported. The pressure in a beam pipe of the 12 GeV proton synchrotron at the National Laboratory for High Energy Physics has been measured with high accuracy by a newly developed hot-cathode extractor type ionization gauge, here called the modulating ion current gauge. The output signal from the gauge head was sent to the synchrotron subcontrol room by a 120 m long cable and the measurement was carried out with full beam in the synchrotron. The miniaturized gauge head has a hemispherical mesh anode and a cylindrical electrode between the ionization region and the ion-collector to modulate the ion current. The modulated signal is sent to an amplifier via a double shielded coaxial cable and after amplification is detected with a phase sensitive detector. This new gauge can reject externally induced noise. The effects both of ions desorbed by electron-impact from the anode and of X-ray photocurrents from the ion-collector can also be avoided.

On the problem of high-energy nucleon–nucleus interactions

On the basis of the analysis of high-energy jets performed in Cracow's Laboratory of High Energy Physics (Holynski et al. 1966) this paper proposes a new model of high-energy nucleon–nucleus interactions. The double maximum angular distribution of the high-energy jets has been explained as the result of the peripheral collision of the incident nucleon and one of the nucleons of the target nucleus and as the consequent central interaction of the now-produced "fast" fireball with another nucleon of the nucleus. The number of generated particles has been estimated from the usual thermodynamic equations. The conditions necessary for the secondary interaction (in the nucleus) of the π mesons produced in the decay of the "slow" fireball have been found. In the light of a comparison of our estimated results with experimental data a possible model of the fireball is discussed.

The use of an on-line digital computer in closed-loop high-energy physics

Since April 1965, IBM and the W. W. Hansen High-Energy Physics Laboratory at Stanford University have been engaged in a joint study of use of on-line computers in high-energy physics experiments. In the High-Energy Laboratory, electrons with energies up to 1.2 BeV, produced by the Stanford Mark III 310-ft linear accelerator, are allowed to bombard various target materials. Electrons, or secondary particles produced by the electrons, are detected with several different kinds of detectors. Information from the detectors is relayed to the data-acquisition area where it is processed and stored, while control information is fed back to nuclear instrumentation by the computer. This paper not only contains a description of the computer and instrument interfaces, but also the application-oriented programming approaches used to operate these devices in various experiments. Several different experiments using the data-acquisition computer system are described, and plans for future modifications and improvements are discussed.

The Extraction and Processing of Data from Bubble Chamber Photographs

AbstractIf an ionizing particle passes through a super heated liquid boiling can take place on the ions created by the particle. These vapour bubbles are photographed under flash illumination and show up the track of the particle. By using two or more cameras the original space position of the track is calculated from measurements made on the different views. The present total rate of production of such photographs in the various high energy physics laboratories throughout the world is about ten million photographs per year. The various methods, in use today, for processing all this information are described and some comments made about possible future development.

E. O. Lawrence Memorial Award

THE Atomic Energy Commission's Ernest Orlando Lawrence Memorial Award for 1961, conferred by the Commission on scientists less than 45 years old who have made “recent, especially meritorious contributions to the development, use or control of atomic energy,” was presented on April 28 to five scientists. Three of the $5000 awards went to physicists: Henry Hurwitz, Jr. (General Electric Research Laboratories, Schenectady), cited for his contributions to reactor theory and design; Conrad L. Longmire (Los Alamos Scientific Laboratory), for his theoretical investigations in the fields of nuclear weapons development and plasma physics; and Wolfgang K. H. Panofsky (High Energy Physics Laboratory, Stanford), for his work in nuclear physics and the international control of nuclear testing. Leo Brewer (Lawrence Radiation Laboratory, University of California, Berkeley), received the award for singular contributions and leadership in the development of high‐temperature chemistry which have permitted major advances in reactor development, and K. G. Wilzbach (Argonne National Laboratory, Argonne, Ill.), for his development of methods of tritium labelling of biologically important compounds which have permitted major advances in biology and medicine.