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P-P Elastic and Charge-Exchange Scattering at about 120 Mev

Description: Observation of antiprotons in a propane or hydrogen bubble chamber offers the possiblity of studying several phenomena for which counter or photographic emulsion techniques are less suitable. Because there is a high ratio of pions, muons, and electrons to antiprotons in the available momentum-analyzed beams, these beams cannot be used in the bubble chamber without an initial purification, which increases the ratio of antiprotons to other particles. Such a purification has been achieved by utilizing the difference in rates of momentum loss in absorbers between antiprotons and other particles. The principle of the method is to pass a momentum-analyzed beam through an absorber. Since particles of unequal mass do not have the same specific ionization they lose different amounts of momentum, and a further magnetic deflection suffices to separate the particles physically according to mass. In this experiment a desirable momentum for antiprotons entering the bubble chamber was 684 Mev/c; however, at this momentum the ratio of undesirable particles to antiprotons at the target where they are produced is about 6 x 10{sup 5}. By starting with 970-Mev/c particles at the target and using the method of differential absorption, they decreased the ratio of undesirable particles (87% {mu}{sup -}, 105 {pi}{sup -}, 3% e{sup -}) to antiprotons entering the bubble chamber at 684 Mev/c to 1.5 x 10{sup 4}. A system of counters indicatd when an antiproton entered the bubble chamber, and although the chamber was expanded on every Bevatron pulse, the lights were flashed and the chamber photographed only when an antiproton entered.
Date: March 28, 1958
Creator: Agnew Jr., Lewis; Elioff, Tom; Fowler, William B.; Gilly, Louis; Lander, Richard L.; Oswald, Larry et al.
Partner: UNT Libraries Government Documents Department

Linac-driven spallation-neutron source

Description: Strong interest has arisen in accelerator-driven spallation-neutron sources that surpass existing facilities (such as ISIS at Rutherford or LANSCE at Los Alamos) by more than an order of magnitude in beam power delivered to the spallation target. The approach chosen by Los Alamos (as well as the European Spallation Source) provides the full beam energy by acceleration in a linac as opposed to primary acceleration in a synchrotron or other circular device. Two modes of neutron production are visualized for the source. A short-pulse mode produces 1 MW of beam power (at 60 pps) in pulses, of length less than 1 ms, by compression of the linac macropulse through multi-turn injection in an accumulator ring. A long-pulse mode produces a similar beam power with 1-ms-long pulses directly applied to a target. This latter mode rivals the performance of existing reactor facilities to very low neutron energies. Combination with the short-pulse mode addresses virtually all applications.
Date: May 1, 1995
Creator: Jason, A.J.
Partner: UNT Libraries Government Documents Department

Recent Studies of Proton Drip-Line Nuclei Using the Berkeley Gas-Filled Separator

Description: The Berkeley Gas-filled Separator provides new research opportunities at Lawrence Berkeley National Laboratory's X-Inch Cyclotron. The use of this apparatus for the study of proton drip-line nuclides is discussed. Preliminary results of {sup 78}Kr bombardments of {sup 102}Pd targets at mid-target energies of 360, 375 and 385 MeV are presented. Improvements planned partially as a result of this measurement are also discussed.
Date: October 7, 1999
Creator: Rowe, M.W.; Batchelder, J.C.; Ninov, V.; Gregorich, K.E.; Toth, K.S.; Bingham, C.R. et al.
Partner: UNT Libraries Government Documents Department

Nuclear structure studies at intermediate energy. Final report, September 1992--May 1995

Description: This constitutes a final report for a two-year grant ending 31 December, 1993, and an additional grant of $15,000 for the period 1 January 1993 to 30 September 1994. At the beginning of 1993 the group consisted of the Principal Investigator (N.H.), two full-time Research Associates (A.S. and V.S.), one part-time Research Associate (M.F.) and one graduate Research Assistant (D.M.). At present only the Principal Investigator in continuing. This report covers the period from September 1992 to April 1995. During this period experiment E 352, ``{sup 208} Pb and {sup 60} Ni (p,t) reaction at 120 MeV`` was completed at the Indiana University Cyclotron Facility (IUCF). A Ph.D. has been awarded (D.M.) on the basis of this work and LAMPF (Los Alamos Meson Physics Facility) E 1201, ``The {sup 40}Ca, (p,2p) reaction at 800 MeV``. A paper on the {sup 208}Pb (p,t) experiment is being prepared for publication, In addition, five papers by members of this group, and four with other collaborators have been published since our last report (September 1992). At present we have one approved experiment (E 1201 above) in the LAMPF cue, but it is unlikely that it will ever be scheduled.
Date: June 1, 1995
Creator: Hintz, N. M.
Partner: UNT Libraries Government Documents Department

Effective temperatures in complete fusion for the system {sup 58}Ni + {sup 58}Ni at 500 MeV bombarding energy

Description: Triple coincidences between complex fragments with Z > 3, light charged particles and {gamma} transitions have been measured for the system {sup 58}Ni+{sup 58}Ni at 500 MeV incident energy. To this end the HILI detector and a 19 pack BaF{sub 2} cluster made of 19 crystals of TAPS geometry have been used. Effective temperatures have been obtained from the ratios of the bound excited level cross sections to the ground states ones for C. N and 0 evaporated after complete fusion of {sup 58}Ni +{sup 58}Ni at 500 MeV incident energy. The dependence of the effective temperature on the charged light particle multiplicity has been investigated.
Date: December 1, 1996
Creator: D`Onofrio, A.; Campajola, L.; Inglima, G. & Roca, V.
Partner: UNT Libraries Government Documents Department

Superconducting Prototype Cavities for the Spallation Neutron Source (SNS) Project

Description: The Spallation Neutron Source project includes a superconducting linac section in the energy range from 192 MeV to 1000 MeV. For this energy range two types of cavities are needed with geometrical beta - values of beta = 0.61 and beta = 0.81. An aggressive cavity prototyping program is being pursued at Jlab, which calls for fabricating and testing of four beta = 0.61 cavities and two beta = 0.81 cavities. Both types consist of six cells made from high purity niobium and feature one HOM coupler of the TESLA type on each beam pipe and a port for a high power coaxial input coupler. Three of the four beta = 0.61 cavities will be used for a cryomodule test at the end of the year 2001. At this time two cavities of each type have been fabricated and the first tests on the beta = 0.61 cavity exceeded the design values for gradient and Q - value: Eacc = 10.3 MV/m and Q = 6.5 x 10{sup 9} at 2.1K. This paper will describe the cavity design with respect to electrical and mechanical features, the fabrication efforts and the results obtained with the different cavities existing at the time of the conference.
Date: June 1, 2001
Creator: Kneisel, Peter; Brawley, John; Bundy, Richard; Ciovati, Gianluigi; Macha, Kurt; Machie, Danny et al.
Partner: UNT Libraries Government Documents Department


Description: Recent results from the Energetic Gamma-Ray Experiment Telescope (EGRET) aboard the Compton Observatory have generated strong interest in space based high-energy (E{sub {gamma}} > 10 MeV) gamma ray astronomy. This science has wetted the authors` curiosity of what might be observed with an instrument having considerably more capability than EGRET, if such a device were practical in these fiscally difficult times. Advances in silicon technology over the past decade, and the resulting rapid drop in costs, encourage the development of a dramatically new type of high-energy gamma ray space telescope based on silicon strip technology. The GLAST team (GLAST stands for Gamma-ray Large Area Space Telescope) has been working for the past two years on the design of such an instrument, and the development of the silicon strip hardware and readout electronics needed to realize this design. As in previous high-energy instruments, GLAST is a pair spectrometer backed by a total absorption electro-magnetic shower counter. Measurement of the energy and direction of the induced electro-magnetic shower provides information about the energy and direction of the incident gamma-ray. However, due to the flexibility and relatively low cost of the silicon strip technology, the telescope has about a factor of 10 increase in effective area over EGRET, and about a factor of 5 increase in field of view. At the same time, the GLAST design is calculated to have much better point source sensitivity, and to have an energy range of 10 MeV < E{sub {gamma}} < 300 GeV. Due to the economics of silicon technology, along with weight, and size savings compared to gas based detector technology, the authors estimate that this instrument can be built and flown as a Delta II mission. Thus, GLAST would easily fit into the NASA intermediate category with an estimated total cost of about $200 ...
Date: March 1995
Creator: Bloom, E. D.
Partner: UNT Libraries Government Documents Department

Operation and improvements of the Fermilab 400 MeV Linac

Description: The 400 MeV Fermilab Linac Upgrade commissioning began August 28, 1993. High energy physics collider operation (run 1b) began in November 1993 and ended March 1, 1996. The Linac, operating at 98% reliability, provided 400 MeV H{sup -} beam to the Booster and 66 MeV H{sup -} beam to the Neutron Therapy Facility. During this time, the beam intensity, which initially was administratively set to 35 MA, rose to a peak of 50 mA while losses decreased significantly. This paper discusses the Linac operation and reliability since the Upgrade.
Date: September 1, 1996
Creator: Allen, L.J.; Popovic, M. & Schmidt, C.W.
Partner: UNT Libraries Government Documents Department

A search for the {Delta}{sup {minus}} wave-function component in light nuclei

Description: We have studied the ({pi}{sup +}, {pi}{sup {+-}}p) reactions on {sup 3}He, {sup 4}He, {sup 6}Li, and {sup 7}Li at incident energy 500 MeV in quasi-free kinematics. A signature attributable to pre-existing {Delta} components of the ground state wave function is observed.
Date: October 1, 1996
Creator: Morris, C.L.; Zumbro, J.D. & Boudrie, R.L.
Partner: UNT Libraries Government Documents Department

Analysis of nucleon-induced fission cross sections of lead and bismuth at energies from 45 to 500 MeV

Description: In order to investigate the applicability of the Cascade-Exciton model (CEM) of nuclear reactions to fission cross sections and hoping to learn more about intermediate-energy fission, the authors use an extended version of the CEM, as realized in the code CEM95 to perform a detailed analysis of proton- and neutron-induced fission cross sections of {sup 209}Bi and {sup 208}Pb nuclei and of the linear momentum transfer to the fissioning nuclei in the 45--500 meV energy range.
Date: August 1, 1998
Creator: Prokofyev, A.V.; Mashnik, S.G. & Sierk, A.J.
Partner: UNT Libraries Government Documents Department

Coincidences between light particles, evaporation residues, and complex fragments emitted in the reaction {sup 58}Ni + {sup 58}Ni at 500 MeV bombarding energy

Description: Light particles (protons and alphas) were measured in coincidence with complex fragments (4 < Z < 10) and evaporation residues (Z > 40) using the large detector array HILI. A {sup 58}Ni beam of 500 MeV extracted from the HHIRF tandem accelerator was used to bombard a {sup 58}Ni target of 99% enrichment. A good account of the proton and alpha spectra in coincidences with the residues can be achieved only by including in the statistical model calculation the emission of complex fragments and allowing a small emission of a dinuclear configuration formed prior to fusion. The relative kinetic energy spectra between the complex fragments and the residues show a typical Coulomb peak consistent with emission from the compound nucleus and the out of plane angular correlation shows that the emission is coplanar.
Date: March 1, 1996
Creator: Gomez del Campo, J.; Shapira, D.; Chavez, E.; Ortiz, M.E.; Dacal, A.; D`Onofrio, A. et al.
Partner: UNT Libraries Government Documents Department

Constraints on solar particle events from comparisons of recent events and million-year averages

Description: Several sets of measurements of the fluxes of solar energetic particles (SEPs) above 10 MeV have been used to apply limits to huge solar particle events (SPEs) in the past. Direct measurements of SEPs are used to get event-integrated solar-proton fluences for SPEs since about 1965. Indirect measurements of SEPs in events from 1956 until 1963 have been used with radioactivities measured in lunar rocks to get event-integrated solar-proton fluences for the larger events back to 1956. A cumulative-probability plot of these event-integrated fluences for all energies above 10 MeV shows a fairly smooth trend from fluences of 10{sub 7} protons/cm{sup 2} up to the largest events (3 x 10{sup 10} protons/cm{sup 2}) but there are no events with higher fluences. Activities of radionuclides in the tops of lunar rocks were used to get average fluxes of solar protons for time periods from {approximately} 10{sup 4} to {approximately} 10{sup 7} years, which are similar to those over the last four decades. These proton fluxes from lunar radionuclides indicate that the long-term trend for huge events does not follow the modern trend for event fluences up to {approximately}3 x 10{sup 10} protons/cm{sup 2}, but that huge events (orders of magnitude larger than {approximately}10{sup 11} protons/cm{sup 2}) have been very rare or nonexistent during the last {approximately}10{sup 7} years.
Date: December 1, 1995
Creator: Reedy, R.C.
Partner: UNT Libraries Government Documents Department

Decay of the {sup 194}Pb superdeformed band

Description: Three experiments using the {sup 174}Yb({sup 25}Mg,5n) reaction at a beam energy of 130 MeV have been performed utilizing the Early Implementation of GAMMASPHERE. The goal of these experiments was to study the decay of the known superdeformed states in {sup 194}Pb to the normal low-lying levels in this nucleus. The statistical decay of these band appears to be suppressed with respect to its {sup 194}Hg isobar. A single discrete transition at 2.746(2) MeV in coincidence with both the superdeformed band and the normal states through which it decays has been identified in these experiments. The evidence for this transition and a discussion of its placement will be presented.
Date: December 9, 1994
Creator: Brinkman, M.J.
Partner: UNT Libraries Government Documents Department

Weapons Neutron Research Facility (WNRF) storage ring system: technical study

Description: The present engineering and theoretical design status of the Weapons Neutron Research Facility (WNRF) proton storage ring are described. It is the intent of this work to show that a practical set of concepts mow exists for construction of this very desirable device for the WNRF. This storage ring will store 800MeV protons from the Los Alamos Meson Physics Facility (LAMPF) to produce intense pulses for the subsequent generation of neutron pulses for direct weapon-mockup testing and studies related to the weapons program. Two basic modes of operation are planned to encompass the scope of experimental investigations. The first mode will consist of loading the ring to attain the greatest unbunched (dc) circulating current that can be contained (a goal for this operation is 100 A) and the release of this current in one pulse of approximately 200-nsec duration. This mode will be used for weapons-related studies that require very intense pulses. The second mode will consist of the accumulation of five 5-nsec-wide bunches of protons circulating in the storage ring, and the subsequent release of these bunches to form a pulse train at the rate of 600 pps on a continuous basis. This mode will be used for weapons- related measurements involving high resolution time-of-flight energy analysis of neutrons. Charge-exchange injection will be employed in both modes of operation because of the demonstrated brightness advantage over conventional synchrotron or betatron space stacking. (auth)
Date: December 1, 1973
Creator: Lieber, A. J.
Partner: UNT Libraries Government Documents Department