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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

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

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

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

Studies of multifragment decay in reverse kinematics

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. 15 refs., 7 figs.
Date: June 1, 1991
Creator: Moretto, L.G.; Roussel-Chomaz, P.; Colonna, M.; Colonna, N. & Wozniak, G.J.
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

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

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

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

Polarized triton scattering from /sup 26/Mg, /sup 27/Al and /sup 28/Si at 17 MeV

Description: Differential-cross-section and analyzing-power angular distributions were measured for 17 MeV tritons elastically scattered from targets of /sup 26/Mg, /sup 27/Al, and /sup 28/Si in the angular range 20 to 160/sup 0/. The experiment was performed at the Los Alamos Scientific Laboratory Van de Graaff facility using the Lamb-shift polarized triton source and the supercube scattering chamber. A pair of detector telescopes with angular resolutions of +-0.4/sup 0/ detected the reaction products, with mass identification and storage performed by an on-line computer. The triton beam intensity available at the target was about 70 nA with a polarization of 0.77. The target thicknesses were about 3 mg/cm/sup 2/, although thinner targets were used for the /sup 27/Al forward-angle data.
Date: January 1, 1980
Creator: Hardekopf, R.A.; Brown, R.E.; Correll, F.D. & Ohlsen, G.G.
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

Recent results in the development of a global medium-energy nucleon-nucleus optical-model potential

Description: Initial results are presented for the determination of a global medium-energy nucleon-nucleus phenomenological optical-model potential using a relativistic Schroedinger representation. The starting point for this work is the global phenomenological optical-model potential of Schwandt )ital et al.), which is based on measured elastic scattering cross sections and analyzing power for polarized protons ranging from 80 to 180 MeV. This potential is optimally modified to reproduce experimental proton reaction cross sections as a function of energy, while allowing only minimal deterioration in the fits to the elastic cross sections and analyzing powers. Further modifications in the absorptive potential were found necessary to extrapolate the modified potential to higher energies. The final potential is converted to a neutron-nucleus potential by use of standard Lane model assumptions and by accounting approximately for the Coulomb correction. Comparisons of measured and calculated proton reaction and neutron total cross sections are presented for /sup 27/Al, /sup 56/Fe, and /sup 208/Pb. Medium-energy optical-model potentials for complex projectiles are briefly discussed in an appendix. 7 refs., 20 figs
Date: February 1, 1988
Creator: Madland, D.G.
Partner: UNT Libraries Government Documents Department

Very hot nuclear systems and their binary and multifragment decay

Description: Compound emission of complex fragments in the reaction {sup 63}Cu + {sup 12}C is used to determine the associated ridge-line potential. Compound binary emission of complex fragments at higher energies is illustrated for a variety of reactions. Complex fragment emission from 18, 26, 31, 35, 45 and 55 MeV/N {sup 139}La/{sup 129}Xe + {sup 12}C, {sup 27}Al, {sup 40}Ca, {sup 51}V, {sup nat}Cu and {sup 139}La reactions has been studied. Multifragment events from these reactions were assigned to sources characterized by their energy and mass through the incomplete-fusion-model kinematics. Excitation functions for the various multifragment channels appear to be nearly independent of the system and bombarding energy. Preliminary comparisons of the data with sequential-statistical-decay calculations are discussed. 16 refs., 9 figs.
Date: October 1, 1990
Creator: Moretto, L.G.; Blumenfeld, Y.; Delis, D. & Wozniak, G.J.
Partner: UNT Libraries Government Documents Department

Measurement of the /sup 27/Al(n,2n)/sup 26/Al reaction cross section for fusion-reactor applications

Description: The /sup 27/Al(n,2n)/sup 26/Al reaction is of considerable interest to the fusion reactor program. Aluminum is an attractive material for many structural applications, and the (n,2n) reaction is the major source of long-lived activity (/sup 26/Al, g.s. T/sub 1/2/ = 7.34 x 10/sup 3/ g). The threshold for this reaction falls within the spread of neutron energies generated by a D-T plasma. Its cross section is therefore a steeply rising function of energy for the primary fusion neutrons. This special feature makes it possible to use this reaction to measure plasma ion temperatures as well as neutron yields and neutron spectral shapes. The /sup 27/Al(n,2n)/sup 26/Al reaction is one of the major sources of displacement damage in Al-metal alloys and other aluminum containing fusion materials, thus the cross section near threshold will strongly affect the amount of displacement damage in these materials as well as the long-lived radioactivity.
Date: January 1, 1983
Creator: Smither, R.K. & Greenwood, L.R.
Partner: UNT Libraries Government Documents Department

Recent results from E802 and E859

Description: Recent single-particle inclusive measurements and two-particle correlation data from E802 and its successor, E859, are presented. The K{sup +}/{pi}{sup +} ratio observed for collisions of 14.6 A{center dot} {sup 28}Si ions on various targets is presented as a function of both forward and transverse energy. Source sizes are determined via interferometry using {pi}{sup +}, {pi}{sup {minus}}, K{sup +} and proton pairs.
Date: January 1, 1991
Creator: Zajc, W.A. (Columbia Univ., New York, NY (United States))
Partner: UNT Libraries Government Documents Department

Target rapidity proton distributions for Si+A collisions at the AGS

Description: Preliminary results are presented for the production of protons in 14.6 A{center dot}GeV/c Si+Al and Si+Au collisions measured by the E859 Phoswich Array at the BNL AGS. The proton data presented cover the laboratory angles of 50--130 degrees and kinetic energies of 40--180 MeV. Slopes and integrated distributions are extracted and comparisons with other experimental data are discussed.
Date: January 1, 1991
Creator: Costales, J.B. (Lawrence Livermore National Lab., CA (United States))
Partner: UNT Libraries Government Documents Department

Neutron spectral and angular distribution measurements for 113 and 256 MeV protons on range-thick Al and sup 238 U targets using the foil activation techniques

Description: Second neutron yields, energy spectra, and angular distributions have been measured at seven angles from 0 to 150{degree} for 113 and 256 MeV protons stopped in range-thick targets of aluminum and depleted uranium ({sup 238}U). Thin foil stacks of ten different materials were activated by secondary neutrons at distances of 20--30 cm from the targets. Following each irradiation, 30--40 different activation products were measured by gamma-ray spectroscopy. These activation rates were then used to adjust neutron energy spectra calculated by the HETC computer code. Activation cross sections were taken from ENDF/BV below 20 MeV, from literature values tested in Be(d,n) fields up to 50 MeV, and from proton spallation data and calculations from 50--250 MeV. Spectral adjustments were made with the STAY'SL computer code using a least-squares technique to minimize {chi}{sup 2} for a covariance matrix determined from uncertainties in the measured activities, cross sections, and calculated flux spectra. Neutron scattering effects were estimated from foil packets irradiated at different distances from the target. Proton effects were measured with (p,n) reactions. Systematic differences were found between the adjusted and calculated neutron spectra, namely, that HETC underpredicts the neutron flux at back angles by a factor of 2--3 and slightly overpredicts the flux at forward angles. 19 refs., 23 figs., 13 tabs.
Date: July 1, 1989
Creator: Greenwood, L.R. & Intasorn, A.
Partner: UNT Libraries Government Documents Department