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MEETING XIII -- BEVATRON RESEARCH CONFERENCE -- TARGET AREA MODIFICATIONS

Description: The following modifications are planned to facilitate greater usefulness of available target space in the west tangent tank: (1) A 3/32-inch x 6-inch x 106-inch aluminum window is to be added to the outer radius tank wall. (2) One 12-inch x 6-inch air lock is to be added on the inside centerline of the reentrant section on the west tangent tank. (3) Two 24-inch x 30-inch openings are to be cut on the beam centerline in the top of the west tangent tank, one at each end. These openings will accommodate photographic plate wells of various kinds and also a large air lock that is being designed. It is suggested that any other modifications to the target area be presented to E. Lofgren as soon as possible so that the modifications can be programmed with respect to operations. The same general policy holds for target location, viz: (a) Small targets - allocations in west tangent tank; and (b) Large targets - allocations in south tangent tank. The design of two general purpose magnets is in the final stages. Copper for the coils will be ordered soon. The characteristics of these magnets are given. Results of magnetic field measurements on the Bevatron are reported, Some of the details and compromises in design of the magnet are discussed. The pole tip confiscation in the 1 x 4-foot aperture nominally n = 0.6 has been cut to a mechanical slope of 0.63. The laminated pole tips have protruding ears which modify the fringing field at low magnet currents to provide the widest possible aperture at injection. These ears are slotted so that they saturate and at intermediate field values become ineffective. This design represents a compromise between maximum useful field width and maximum obtainable field at peak current. The pole tips contain 21 ...
Date: March 23, 1954
Creator: Chupp, Warren
Partner: UNT Libraries Government Documents Department

MEETING XVI -- BEVATRON RESEARCH CONFERENCE -- BEVATRON OPERATION

Description: The occurrence of a fault April 7 caused a short in the stator winding of one of the main generators. Repairs will require at least one month and the total time the generator will be down can be determined only after a further inspection of the damage. In a week or two, after a thorough inspection of the generator and the ignitron system, Bevatron operation will be continued on one generator. Since the targets of use in a Bevatron experiment will depend greatly on the nature of the experiment and the techniques to be employed the ideas presented here relate primarily to the area of research which involves the detection with counters of heavy mesons emitted in the backward direction in the laboratory system. These mesons and their decay products have low kinetic energy over the entire range of Bevatron energies above threshold for production. For this reason discrimination by means of momentum resolution, collimating slits, ionization density and range will be possible.
Date: April 13, 1954
Creator: Lofgren, E.J.
Partner: UNT Libraries Government Documents Department

Mixing and CP violation in the D0 and B0(s) systems

Description: Recent developments for mixing and CP violation in the D0 and Bs systems are reviewed, including (i) the recently emerging evidence for D0-D0bar mixing and the interpretations of the measurements; (ii) the theoretical status of the calculations of Delta(Gamma_D) and Delta(m_D); (iii) some implications of the measurement of Bs mixing for new physics.
Date: May 7, 2007
Creator: Ligeti, Zoltan & Ligeti, Zoltan
Partner: UNT Libraries Government Documents Department

MEETING VII-BEVATRON RESEARCH CONFERENCE--COUNTING EQUIPMENT FOR THE BEVATRON

Description: This discussion will review the results of a survey of present plans for the Bevatron counting equipment. Proposed counting facilities, tentative specifications for desired counting equipment, a view of past counting techniques, and some of the later associated circuits will be considered.
Date: November 17, 1953
Creator: Wiegand, Clyde.
Partner: UNT Libraries Government Documents Department

MEETING XII -- BEVATRON RESEARCH CONFERENCE -- BEVATRON OPERATION

Description: On February 2, the first 10 Mev proton beau was injected from the linear accelerator. Injection parameters were varied to study first turn beams with the magnet excited by a d-c generator. A few minutes after the magnetic field had been adjusted to the value calculated from magnetic measurements. the 180{sup o} beam was observed on fluorescent flags and measured with Faraday cups. During the remainder of the week several radio frequency components were installed and operated. Ground current signals in various pieces of equipment were a limitation in detecting.
Date: March 16, 1954
Creator: Cork, Bruce.
Partner: UNT Libraries Government Documents Department

MEETING XV -- BEVATRON RESEARCH CONFERENCE -- BEVATRON STATUS

Description: On April 1, a new energy peak of 6.1 Bev was attained with the Bevatron. Scattered particles monitored with a counter telescope in triple coincidence gave approximately 100 counts per beam pulse. April 2s the machine was down to air to allow work on beam monitoring equipment. Test operations resumed April 5. Though the total number of accelerated particles is still small, due to low energy beam losses, some cloud chamber tracks have been observed. Several plates have been exposed for Goldhaber. Stars with up to 29 prongs have been observed. The following consists of a discussion of the administration, operation and some of the experimental techniques evolved in the use of the Cosmotron.
Date: April 6, 1954
Creator: Lofgren, E.J.
Partner: UNT Libraries Government Documents Department

Monthly Progress Report No. 61 for May, 1948

Description: This is the University of California, Radiation Laboratory monthly progress report for May 1948. It discusses the following: (1) 184-inch Cyclotron Program; (2) 60-inch Cyclotron Program; (3) Synchrotron Program; (4) Linear Accelerator Program; (5) Experimental Physics; (6) Theoretical Physics, (7) Isotope Separation Program; (8) Chemistry Departments; (9) Medical Physics; and (10) Health Physics and Chemistry.
Date: May 31, 1948
Creator: Authors, Various
Partner: UNT Libraries Government Documents Department

Electronic Circuits Lectures

Description: The two-electrode vacuum tube, or diode, consists of an electron-emitting cathode surrounded by a positive anode (plate). A plot of plate current (i{sub b}) vs plate voltage (e{sub b}) is shown. At low anode voltages, the anode current is limited by the repelling effect that the negative electrons already in the space have on the electrons just being emitted (space-charge effect). When a full space charge is present, the plate current depends upon the plate voltage according to Childs law: i{sub b} {approx} e{sub b}{sup 3/2}. Increasing the plate voltage eventually results in an electron flow equal to total cathode emission, after which further increases in anode voltage will produce practically no additional current (voltage saturation). However, for high field stresses, additional electrons are pulled out of the cathode (field emission), increasing the current even further.
Date: December 1, 1947
Creator: Mozley, Robert
Partner: UNT Libraries Government Documents Department

Excitation Function of the Reaction C12(p,pn)C11 at High Energies

Description: Chupp and McMillan have recently measured the excitation curve for the reaction C{sup 12}(pnpn)C{sup 11} at high energies. Using the model of the nucleus described by Serber, the excitation curve of the above reaction has been calculated for energies up to 100 Mev. The excitation of the nucleus is determined on the basis that the incident proton makes individual collisions with the nucleons, the transferred energy exciting the nucleus. n-p collisions are taken to be three times more probable than n-n or p-p collisions. Charge exchange is assumed. The calculations were made for both 50% and 100% charge exchange. The decay of the excited nucleus is treated by the usual evaporation mode.
Date: November 1, 1947
Creator: Heckrotte, W. & Wolff, Peter
Partner: UNT Libraries Government Documents Department

FAST BEAM CHOPPERS FOR THE ELECTRON-RING ACCELERATOR

Description: Two beam choppers were constructed which produce an approximately square, 20-ns pulse of 3+-MeV electrons out of the best portion of the 300-ns Astron beam or an 8-{micro}s microwave electron linac beam for injection into the electron-ring accelerator (ERA) compressor. The choppers are impedance-matched traveling-wave devices which deflect the beam with equal strength electric and magnetic forces, and are powered with either three-electrode spark gaps or thyratrons and a 20-ns pulse line. The electron beam is biased out of the beam-transport system with a dc magnetic field, and switched into it with the chopper.
Date: February 7, 1969
Creator: Faltens, Andris & Kerns, Cordon.
Partner: UNT Libraries Government Documents Department

Field Theory On the World Sheet: Mean Field Expansion And Cutoff Dependence

Description: Continuing earlier work, we apply the mean field method to the world sheet representation of a simple field theory. In particular, we study the higher order terms in the mean field expansion, and show that their cutoff dependence can be absorbed into a running coupling constant. The coupling constant runs towards zero in the infrared, and the model tends towards a free string. One cannot fully reach this limit because of infrared problems, however, one can still apply the mean field method to the high energy limit (high mass states) of the string.
Date: January 10, 2007
Creator: Bardakci, Korkut
Partner: UNT Libraries Government Documents Department

The Fission of thorium with Alpha Particles

Description: Soon after the discovery of fission, Meitner, Bretscher and Cook found differences in the decay of various chemical fractions separated from uranium irradiated with slow neutrons and thorium irradiated with fast neutrons respectively and suggested that a difference existed in the distribution of fission products in the two cases. In 1940, Turner suggested that the distribution in various modes of fission should be investigated. The fact that elements such as tin, cadmium, palladium, and silver were found in fast neutron and deuteron fission of uranium and thorium before they were found in slow neutron fission of uranium suggested that the middle region of the distribution was raised as the energy of the incident particle was increased. Since the compound nucleus formed in the fission of thorium with alpha particles is U{sup 236}, the same compound nucleus formed in the fission of U{sup 235} with neutrons, it is of interest to study the fission of thorium with alphas and compare the resulting distribution of fission products with that found with uranium with slow and thorium with fast neutrons. Any difference between the various results where the same compound nucleus is formed must be due to differences in energy content and possible differences in distribution of the nucleons in the compound nucleus at the time of fission.
Date: October 15, 1948
Creator: Newton, Amos S.
Partner: UNT Libraries Government Documents Department

The Formation of U232 by Helium Ions of Thorium

Description: The production of U{sup 232} by the sum of {alpha},4n and {alpha},p 3n reactions on thorium has been studied. The cross section at an average energy of 37.5 Mev was 0.013 barns and the threshold for the reaction was about 30 Mev.
Date: April 14, 1948
Creator: Newton, Amos S.
Partner: UNT Libraries Government Documents Department

Excitation Function of the Reaction C12(n,2n)C11 at High Energies

Description: The excitation curve for the reaction C{sup 12}(n,2n)C{sup 11} has been calculated for energies up to 100 Mev. The calculations were done as described in the preceding letter for the similar reaction of C{sup 12} under proton bombardment. The results of the calculations for 50% charge exchange are shown in Figure 1. The calculated cross section for the reaction at 90 Mev is: .011 barns for 100% charge exchange and .013 barns for 50% charge exchange. The experimental value is 0.025 {+-} .004 barns. The ratio of the cross section of the reaction C{sup 12}(pnpn)C{sup 11} to the cross section of the above reaction at 90 Mev is 5.8 for 100% charge exchange and 3.8 for 50% charge exchange. The experimental ratio is 2.7 at 90 Mev. This difference in cross sections between the two reactions is established by two factors. Firstly, there is the part played by charge exchange in the C{sup 12}(pnpn)C{sup 11} reaction which leads to excited N{sup 12} with the subsequent boiling off of a proton, while a similar exchange process cannot take place for the C{sup 12}(n2n)C{sup 11} reaction. Secondly, there is the difference between the contributions of the knock out process as a result of the difference in the n - p and the n - n cross sections, which favors the p + C{sup 12} knock out reaction. It will be noted that the parts of the reactions which go through excited C{sup 12}, while practically equal, are so small that they do not greatly affect either reaction. Although the results of these calculations do not agree too closely with the experimental results, the results are probably as good as are to be expected because of the crudity of the assumed model. The results do, though, seem to give a good qualitative picture ...
Date: November 1, 1947
Creator: Heckrotte, Wolff & Wolff, Peter
Partner: UNT Libraries Government Documents Department

F-Theory, T-Duality on K3 Surfaces and N = 2 Supersymmetric Gauge Theories in Four Dimensions

Description: We construct T-duality on K3 surfaces. The T-duality exchanges a 4-brane R-R charge and a O-brane R-R charge. We study the action of the T-duality on the moduli space of O-branes located at points of K3 and 4-branes wrapping it. We apply the construction to F-theory compactified on a Calabi-Yau 4-fold and study the duality of N = 2 SU(N{sub c}) gauge theories in four dimensions. We discuss the generalization to the N = 1 duality scenario.
Date: February 26, 1997
Creator: Hori, K. & Oz, Y.
Partner: UNT Libraries Government Documents Department

The Fission of Thorium with Alpha Particles

Description: The fission distribution of fission of thorium with alpha particle of average energy 37.5 Mev has been measured by the chemical method. The distribution found shows that the characteristic dip in the fission yield mass spectrum has been raised to within a factor of two of the peaks compared to a factor of 600 in slow neutron fission of U{sup 235}. The raise in the deip has caused a corresponding lowering in fission yield of these elements at the peaks. The cross section for fission of thorium with 37.5 Mev alphas was found to be about 0.6 barn, and the threshold for fission was found to be 23 to 24 Mev.
Date: April 15, 1948
Creator: Newton, Amos S.
Partner: UNT Libraries Government Documents Department

Loss of Radioactivity from Barium Carbonate Samples

Description: The exchange loss of radioactivity from solid samplos of barium carbonate through the agency of carbonic acid and its ions has been investigated under a variety of conditions. It is concluded that the losses observed are greatly dependent upon the method of sample preparation, in particular the nature or any heat treatment which the sample materials undergo.
Date: January 9, 1948
Creator: Yankwich, Peter E.
Partner: UNT Libraries Government Documents Department

MEETING IX - BEVATRON RESEARCH CONFERENCE--BEVATRON PHYSICS

Description: A large number of experiments relating to nuclear structure and materialization of energy will fall within the energy range of primary and secondary particles available from the Bevatron. Some experiments of interest are outlined below with pertinent comments. Proton-proton scattering can be extended to the high energy range using liquid hydrogen targets and hydrogenous materials by bombarding the target with the internal beam or using externally scattered protons. Proton-deuteron scattering measurements using liquid deuterium targets or solid materials can also be extended. Proton scattering from heavier nuclei may be found less difficult to interpret at these level energies as the nucleons will interact more or less independently. The wavelength of the bombarding particles will now be much smaller than nucleon diameters. Nuclear collisions represent by far the most important interaction between high energy nucleons and matter. Proton-neutron charge exchange interaction within the internal target will provide an external flux of neutrons which can be used directly for total nuclear cross section measurements and neutron-proton scattering. Low energy measurements, say below 200 Mev; show that nuclear interaction cross sections do not go down as 1/{lambda} as reactions become predominantly nuclear rather than electromagnetic. Measurements can now be extended into the Bev range to investigate the complex as opposed to the point charge concept of nuclear interactions. The external neutron beam may also provide high energy protons in charge exchange interactions with external targets. Mesons produced in the internal target will provide external meson beams of all types for cross section measurements over a large range of energies. Sufficient energy will be available for production of V particles with reasonable cross sections. The primary event leading to the production of V particles and the characteristic mode of decay can be studied. These events are best adapted to cloud chamber techniques wherein co-planer ...
Date: December 15, 1953
Creator: Karplus, Robert
Partner: UNT Libraries Government Documents Department

MEETING XIV -- BEVATRON RESEARCH CONFERENCE -- CHEMISTRY EXPERIMENTS

Description: The main purpose of Chemistry Division personnel in using the Bevatron will be to learn as much as possible about nuclear reactions in the Bev energy range using the radiochemical approach. The type and extent of these experiments will depend greatly on the beam intensity. Significant results can be obtained at 10{sup 6} or 10{sup 7} protons per pulse, but it is highly desirable that this figure ultimately be raised to 10{sup 10} or greater.
Date: March 29, 1954
Creator: Hyde, Earl K.
Partner: UNT Libraries Government Documents Department