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Particle production at AGS energies

Description: The authors discuss particle production from 14.6 A{center_dot}GeV/c Si and 11.6 A{center_dot}GeV/c Au projectiles on Al and Au targets. The second-level trigger utilized by E859 allows high precision measurements of K{sup {minus}}, {bar p}, {Lambda} and {bar {Lambda}}. The {bar {Lambda}} yield is larger than expected, and a surprisingly large fraction of the {bar p}`s are observed to arise from the decay of {bar {Lambda}}.
Date: March 1, 1995
Creator: Steadman, S.G.; Rothschild, P.J.; Sung, T.W. & Zachary, D.
Partner: UNT Libraries Government Documents Department

Adaptation of a nucleon-nucleus elastic scattering model for LAHET{trademark}

Description: The LAHET Monte Carlo code for the transport and interaction of nucleons, pions, muons, light ions, and antinucleons has been upgraded by the addition of an elastic scattering model for neutrons above 15 MeV and protons above 50 MeV. Earlier elastic scattering in LAHET has been limited to neutrons below 100 MeV, using a library of elastic optical-model cross sections generated using the Bechetti-Greenlees potential. The new methodology has been adapted from the HERMES code. However, the sampling algorithm for the center-of-mass scattering angle has been completely rewritten, and the elastic cross section data has been replaced below 400 MeV. The new method is viewed as an intermediate step in the effort to provide a library of both elastic and non-elastic cross sections from a global optical-model potential for LAHET usage.
Date: July 1, 1995
Creator: Prael, R.E. & Madland, D.G.
Partner: UNT Libraries Government Documents Department

Analysis of pion production data from E-802 at 14.6 GeV/c using ARC

Description: We compared the invariant cross sections for pion production by a 14.6 GeV/c proton beam on Be, Al, Cu and Au targets from the measurements of Abbott et.al. with predictions of the ARC program. The agreement was found to be good in the region where data exists. Most pions are found at low momenta in the lab frame. Unfortunately very little data exists for low momentum pions.
Date: July 1, 1995
Creator: Kahana, D. & Torun, Yagmur
Partner: UNT Libraries Government Documents Department

Characterization of short pulse laser-produced plasmas at the Lawrence Livermore National Laboratory ultra short-pulse laser

Description: The K-shell emission from porous aluminum targets is used to infer the density and temperature of plasmas created with 800 nm and 400 nm, 140 fs laser light. The laser beam is focused to a minimum spot size of 5 {mu}m with 800 nm light and 3 {mu}m with 400 nm light, producing a normal incidence peak intensity of 10{sup 18} Watts/cm{sup 2}. A new 800 fs x-ray streak camera is used to study the broadband x-ray emission. The time resolved and time integrated x-ray emission implies substantial differences between the porous target and the flat target temperature.
Date: July 14, 1993
Creator: Shepherd, R.; Price, D.; White, W.; Osterheld, A.; Walling, R.; Goldstein, W. et al.
Partner: UNT Libraries Government Documents Department

Cross sections for the Al(n,xn) and Al(n,x$gamma$) reaction between 1 and 20 MeV

Description: Differential cross sections for the production of secondary neutrons and photons from aluminum have been measured at 127$sup 0$ (lab) for incident neutron energies in the range 1 to 20 MeV. An electron linac was used as a neutron source with a white spectrum. Incident neutron energies were determined using time-of-flight techniques for a source-to-sample distance of 48 m. Secondary spectra were determined by unfolding the pulse-height distributions observed in a NE-213 scintillation counter. The results are compared to the current evaluated data file (ENDF/B-IV, MAT 1193). (auth)
Date: January 1, 1976
Creator: Morgan, G.L. & Perey, F.G.
Partner: UNT Libraries Government Documents Department

Two particle correlations at mid-rapidity in Si+A and Au+Au from E859/E866

Description: Two particle correlation measurements for {ital Si-A} and {ital Au- Au} collisions from Brookhaven E859 and E866 are discussed. These measurements allow us, with some interpretation, to deduce the size of the participant region in a heavy ion collision. We show that various source parameterizations yield consistent results and we explore the dependence of the apparent source size on the pion yield.
Date: February 1, 1997
Creator: Baker, M.D. & Collaboration, E802
Partner: UNT Libraries Government Documents Department

Assessment of some optical model potentials in predicting neutron cross sections

Description: Optical model potential parameters play an important role in the evaluation of nuclear data for applied purposes. The IAEA Coordinated Research Program on {open_quotes}Reference Input Parameter Library for Evaluation of Nuclear Data for Application in Nuclear Technology{close_quotes} aims to release a reference input file of various types of parameters for the evaluation of nuclear cross sections using nuclear model codes. Included in the parameter files are a collection of optical model potentials that are available in the literature to evaluate these cross sections. As part of this research program we assess the applicability of these potentials over a range of target mass and projectile energy.
Date: March 1, 1998
Creator: Kumar, A.; Young, P.G. & Chadwick, M.B.
Partner: UNT Libraries Government Documents Department

Charged particles produced in neutron reactions on nuclei from beryllium to gold

Description: Charged-particle production in reactions of neutrons with nuclei has been studied over the past several years with the spallation source of neutrons from 1 to 50 MeV at the Los Alamos Neutron Science Center (LANSCE). Target nuclides include 9Be, C, 27Al, Si, 56Fe, 59Co, 58,60Ni, 93Nb and 197Au. Proton, deuteron, triton, 3He and 4He emission spectra, angular distributions and production cross sections have been measured. Transitions from the compound nuclear reaction mechanism to precompound reactions are clearly seen in the data. The data are compared with data from the literature where available, with evaluated nuclear data libraries, and with calculations where the selection of the nuclear level density prescription is of great importance. Calculations normalized at En = 14 MeV can differ from the present data by a factor of 2 for neutron energies between 5 and 10 MeV.
Date: August 1, 1997
Creator: Haight, R.C.
Partner: UNT Libraries Government Documents Department

A cross section measurement of charm hyperons {Xi}{sub c}{sup +} and {Xi}{sub c}{sup 0} in 250 GeV p/K/{pi}-nucleon interactions

Description: Fermilab Experiment 769 used a charge-selected, hadron beam of mean energy 250 GeV/c, composed of pions, kaons, and protons, impinging on beryllium, aluminum, copper and tungsten targets. Using a sample of approximately 4000 {Xi}{sub s}{sup {minus}} {yields} {Lambda}{sup 0}{pi}{sup {minus}} decays, measurements of the charm baryon forward cross sections times branching ratio {pi}{sup {+-}}N {yields} {Xi}{sub c}{sup +}X and {pi}{sup {+-}}N {yields} {Xi}{sub c}{sup 0}X are presented. Upper limits on {alpha} x BR are also determined for the states {Xi}{sub c}{sup +} {yields} {Xi}{sub s}{sup {minus}}{pi}{sup +}{pi}{sup +} and {Xi}{sub c}{sup 0} {yields} {Xi}{sub s}{sup {minus}}{pi}{sup +} produced in (p, {pi}{sup +}, {pi}{sup {minus}}, K{sup +}, K{sup {minus}})-nucleon interactions.
Date: May 2, 1995
Creator: Francisco, J. & Vergara, A.
Partner: UNT Libraries Government Documents Department

Fission, total and neutron capture cross section measurements at ORELA for {sup 233}U, {sup 27}Al and natural chlorine

Description: The authors have made use of the Oak Ridge Electron Linear Accelerator (ORELA) to measure the fission cross section of {sup 233}U in the neutron energy range of 0.36 eV to {approximately} 700 keV. This paper reports integral data and average cross sections. In addition they measured the total neutron cross section of {sup 27}Al and natural chlorine, as well as the capture cross section of Al over an energy range from 100 eV up to about 400 keV.
Date: August 1, 1998
Creator: Guber, K.H.; Spencer, R.R.; Leal, L.C.; Larson, D.C.; Santos, G. Dos; Harvey, J.A. et al.
Partner: UNT Libraries Government Documents Department

What can we learn from p{perpendicular} spectra in heavy-ion collisions at the AGS?

Description: Inclusive and semi-inclusive cross-sections for production of pions, kaons, and protons in Si+Al, Si+Cu, and Si+Au collisions, measured at the nucleon-nucleon center-of-mass rapidity are presented. The functional forms of the spectra are discussed. The centrality dependence of the inverse m{perpendicular} slopes is shown. Deviations in the spectra from pure exponential-m{perpendicular} distributions are discussed. The effects of resonance decays on the shape of the pion spectra are studied using previously measured p-p data, Si+Al data from E802, and the ARC model.
Date: May 1, 1994
Creator: Cole, B. A. (Columbia Univ., New York, NY)
Partner: UNT Libraries Government Documents Department

Multiplicity dependence of two-pion correlations

Description: Experiment E859 has measured two-pion correlations for 14.6 A{center_dot}GeV/c {sup 28}Si + Au and {sup 28}Si + Al systems as a function of total charged particle multiplicity. The data have been divided into three multiplicity regions for each system, and fits to two-dimensional Gaussian sources have been performed. The extracted source parameters R{sub l} and {tau} show little or no multiplicity dependence while the parameters R{sub t} and R show a slight dependence. Two-pion correlations were also measured for the 11.6 A{center_dot}GeV/c {sup 197}Au + Au system as part of experiment E866. The rms radius (R{sub rms}) for this system was found to be 7.03 {plus_minus} 0.53 fm, consistent with a scaling of R{sub rms} = 1.2A{sub p}{sup 1/3}, where A{sub p} is the number of projectile nucleons.
Date: December 31, 1993
Creator: Soltz, R. A. & Collaboration, E802
Partner: UNT Libraries Government Documents Department

Particle production in p+A collisions at 14.6 GeV/c

Description: In the last few years, studies of heavy-ion collisions at high energy have produced new insight into the production of nuclear matter at high baryon density and temperature. While heavy-ion reactions at AGS energy are now well characterized, to clarify and test our understanding of the reaction mechanism of these collisions it is important to study the underlying processes involved. The study of p-A collisions should be particularly useful to understand in which way A-A collisions differ from the simple superposition of nucleon-nucleon collisions and it may be a specially severe test of the validity of the models in describing the transition from a single collision problem to a thermodynamic problem mainly defined by a few observables. In particular, p-A collisions should be sensitive to the way nucleons propagate in the nuclear medium and thus provide more insight on: the importance of rescattering, the stopping power of normal nuclear matter, and possibly on the influence of the nuclear matter density and temperature on the hadronic cross sections. In this paper we present the transverse energy and charged particle multiplicity distributions in proton induced collisions on Al, and Pb targets at 14.6GeV/c. These data have been obtained as part of the E814 collaboration and are thus immediately comparable to similar data obtained for {sup 28}Si and Au induced reactions at the same energy.
Date: December 31, 1993
Creator: Rosati, M. & Collaboration, E814
Partner: UNT Libraries Government Documents Department

Target dependence of proton source sizes at 14.6 A GeV/c

Description: Relative-momentum correlations have been measured for pairs of protons from central collisions of 14.6 A-GeV/c {sup 28}Si with {sup 27}Al, {sup 107}Ag, and {sup 197}Au nuclei. The protons were detected in a region centered near a laboratory rapidity of 1.2. Theoretical correlation functions are convoluted with the spectrometer response function and fitted to the data to derive the source volume. The fitted radii are corrected for small relativistic effects. The extracted volumes are consistent with a crude geometrical overlap model and depart from {pi} - {pi} and K-K data trends which suggest a source size closer to that of the projectile.
Date: May 1, 1994
Creator: Stephans, G. S. F.
Partner: UNT Libraries Government Documents Department

Study of {sup 27}Al(n,x{gamma}) reactions up to a neutron energy of 400 MeV

Description: The prompt {gamma}-radiation from the interaction of fast neutrons with Al was measured using the white neutron beam of the WNR facility at the Los Alamos National Laboratory. Partial production cross sections for residual nuclei in the range from F to Al were measured from threshold up to 400 MeV by observing the most intense {gamma}-transitions between low lying levels of these nuclei. Two-dimensional neutron time-of-flight versus gamma pulse height spectra from the interaction of the neutrons with Al were observed after flight-paths of about 20 and 40 m with a high-purity Ge-detector. The neutron cross sections for prominent {gamma}-transitions in a large number of residual nuclei could be derived with typical uncertainties of 10--20% up to a neutron energy of 400 MeV. The energy resolution varies from {approx}0.2 MeV at 10 MeV to {approx}50 MeV at 400 MeV. In the low energy range (up to 60 MeV) the results are compared with nuclear model calculations using the code GNASH. A very good overall agreement is obtained without special adjustment of parameters.
Date: June 1, 1994
Creator: Hitzenberger, H.; Pavlik, A.; Vonach, H.; Chadwick, M. B.; Haight, R. C.; Nelson, R. O. et al.
Partner: UNT Libraries Government Documents Department

Particle production at high p{sub {perpendicular}} in {sup 28}Si+A collisions at 14.6 A{center_dot}GeV/c

Description: Single particle inclusive spectra are presented for particle production in Si+Al and Si+Au reactions at the nucleus-nucleon center-of-mass rapidity for projectiles incident at 14.6 A{center_dot}GeV/c. The invariant cross sections are all well described by an exponential dependence in the transverse mass m{perpendicular}. An analysis in terms of different components in p{sub {perpendicular}}{sup 2} shows the importance of resonance production and decay as a reaction mechanism at AGS energies.
Date: August 1, 1992
Creator: Steadman, S. G. & Collaboration, E802
Partner: UNT Libraries Government Documents Department

Particle spectra and correlations from Experiment 814

Description: In this article the authors summarize recent results from the E814 forward spectrometer on proton and pion distributions that give insight into the initial baryon (and energy) density achieved in central collisions as well as the temperature of the system at freeze-out. An independent measure for the latter, complementing the slope constants of particle spectra, is the population of nucleon excited states, in particular the {Delta}(1232) resonance. Besides its influence on the pion spectra it has also been identified directly in the experiment and first results are discussed. The first results from E814 on kaon spectra at low transverse momentum p{sub t} are presented; the spectra show an unexpected very steep rise at the lowest p{sub t}. The two pion correlation function has been studied for positive and negative pions and the authors show that it is consistent with a large source size at freeze-out. Finally, they show that the present data give a consistent picture of a system in thermal and chemical equilibrium at freeze-out.
Date: August 1, 1994
Creator: Stachel, J. & Univ., E814 Collaboration: BNL-GSI-McGill Univ.-Univ. of New Mexico-Univ. of Pittsburgh-SUNY Stony Brook-Univ. of Sao Paulo-Wayne State Univ.-Yale
Partner: UNT Libraries Government Documents Department

Distribution of products in the reaction /sup 20/Ne + Al. [118 and 167 MeV]

Description: The measurement and preliminary analysis of the distribution of products with Z between 2 and 21 and A between 3 and 43 from 118- and 167-MeV reactions of /sup 20/Ne with Al are reported. Experimental conditions were adequate to allow resolution of individual isotopes over this entire range, and measurements were made at several angles for each bombarding energy. Measured relative cross sections of the heavier products were compared with predictions of a statistical-model evaporation calculation. The overall agreement between experiment and theory was rather good; however, certain discrepancies between calculation and experiment for low Z and A at 167 MeV may be troublesome. 3 figures. (RWR)
Date: January 1, 1980
Creator: Ferguson, R.L.; Gavron, A.I.; Obenshain, F.E.; Plasil, F.; Robinson, R.L.; Shapira, D. et al.
Partner: UNT Libraries Government Documents Department

Preliminary results from Brookhaven Experiment 802 with 14. 5 GeVu /sup 28/Si

Description: Preliminary data on beam calorimetry, charged particle multiplicities, pseudo-rapidity distributions and hadron spectroscopy from /sup 28/Si + Al and Au at 14.5 GeV per nucleon are presented. Comments on nuclear stopping, multiplicity systematics, and K..pi.. ratios are offered. 5 refs., 6 figs., 1 tab.
Date: January 1, 1987
Partner: UNT Libraries Government Documents Department

Systematics of complex fragment emission from La induced reactions at E/A = 47 MeV

Description: Complex fragment (Z > 2) emission was studied in the reverse kinematics reactions of /sup 139/La on /sup 27/Al and /sup nat./Cu at a bombarding energy of E/A = 47 MeV. Experimental results from inclusive and coincidence measurements for two- and three-fold complex fragments events are presented. Measured cross sections and Z/sub 1/-Z/sub 2/ correlations show a predominately binary-decay process for the La + Al reaction, while the La + Cu reaction is dominated by multi-body decay. 18 refs., 9 figs., 1 tab.
Date: March 1, 1989
Creator: Kehoe, W.L.; Mignerey, A.C.; Bradley, S.; Marchetti, A.; Bowman, D.R.; Charity, R.J. et al.
Partner: UNT Libraries Government Documents Department

Cross sections and differential spectra for reactions of 2-20 MeV neutrons of /sup 27/Al

Description: This report summarizes product yields, secondary n,p and ..cap alpha.. spectra, and ..gamma..-ray spectra calculated for incident neutrons of 2-20 MeV on /sup 27/Al targets. Results are all from the code ALICE, using the version ALISO which does weighting of results for targets which are a mix of isotopes. Where natural isotopic targets are involved, yields and n,p,..cap alpha.. spectra will be reported weighted over isotopic yields. Gamma-ray spectra, however, will be reported for the most abundant isotope.
Date: January 1, 1988
Creator: Blann, M. & Komoto, T.T.
Partner: UNT Libraries Government Documents Department

Investigation of the intermediate-energy deuteron breakup reaction

Description: The Udagawa-Tamura formalism is employed to calculate the proton singles both in the bound and unbound regions. Both the Elastic-Breakup (EB) and the Breakup-Fusion (BF) processes are considered to calculate the doubly-differential cross section for light and intermediate mass nuclei. The calculated spectra for 25 and 56 MeV deuterons reproduce the experimental spectra very well except for the spectra at large angle and at low energies, of the outgoing particle. Contributions due to precompound and evaporation processes are estimated to supplement the spectral results based on the Elastic-Breakup and Breakup-Fusion mechanisms. An extension of the model calculations to higher deuteron energies is being made to test the (EB + BF) model limitations. 5 refs., 1 fig.
Date: January 1, 1989
Creator: Divadeenam, M.; Ward, T.E.; Mustafa, M.G.; Udagawa, T. & Tamura, T.
Partner: UNT Libraries Government Documents Department

Transverse energy distributions in Si + nucleus collisions at 10 GeV/nucleon

Description: Transverse energy distributions have been measured for collisions of 10 GeVnucleon Si with targets of Al, Cu and Pb using a combination of a NaI wall and a uranium based sampling calorimeter. The measured cross sections d..sigma..dE/sub T/ and dE/sub T/d)eta are consistent with full stopping and an increase, with increasing values of E/sub T/, of energy flow into large angles. 4 refs., 7 figs., 2 tabs
Date: August 1, 1987
Creator: Bassalleck, B; Braun-Munzinger, P.; Cleland, W.; G., David; Farooq, A.; Fatyga, M. et al.
Partner: UNT Libraries Government Documents Department

Experimental and theoretical characterization of multifragment events

Description: Multifragment events are shown to be associated with specific sources characterized by their mass and excitation energy through the incomplete fusion model. Excitation functions for the different multifragment decay channels are found to be almost independent of the system and the incident energy. Preliminary comparisons of the data with dynamical calculations followed by statistical decay calculations are discussed. 18 refs., 7 figs., 1 tab.
Date: June 1, 1991
Creator: Moretto, L.G.; Roussel-Chomaz, P.; Colonna, M.; Colonna, N. & Wozniak, G.J.
Partner: UNT Libraries Government Documents Department