177 Matching Results

Search Results

Advanced search parameters have been applied.

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

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

Preliminary Feasibility Study of Using Solid-State Nuclear Magnetic Resonance Spectroscopy to Characterize Hanford Tank Waste Solids

Description: This report describes experiments performed in FY 2001 to examine the feasibility of using nuclear magnetic resonance (NMR) spectroscopy to characterize Hanford tank sludge solids. The results demonstrate the potential utility of magic-angle spinning solid-state NMR spectroscopy for this purpose. We have shown that 27Al NMR signals can be easily detected in samples simulating the compositions of Hanford tank sludge solids. Different Al-containing species can be distinguished on the basis of a number of characteristics, including resonance frequency, lineshape, and response to excitation pulse length of the 27Al NMR signal. This work also indicates that 23Na NMR can likely be used to identify specific Na-containing phases present in tank wastes. It is expected that other NMR-active nuclides can be probed for information about specific phases present in tank-waste solids.
Date: October 31, 2001
Creator: Cho, Herman M
Partner: UNT Libraries Government Documents Department

Evaluation of {sup 235}U, {sup 238}U, {sup 6}Li, and {sup 27}Al Cross Sections

Description: Good nuclear data are essential for accurate prediction of reactor parameters. Several cross section libraries are currently available for use with GLASS physics calculations. In recent Mark 15 and Mark 22 studies, cross section data were developed to provide more accurate buckling calculations for Mark 15 and Mark 22 charges. This report documents evaluation of these new data for universal application.
Date: May 17, 2001
Creator: Chandler, J.R.
Partner: UNT Libraries Government Documents Department

Neutron Capture and Neutron Total Cross Sections Measurements for {sup 27}Al at the Oak Ridge Electron Linear Accelerator

Description: We have used the Oak Ridge Electron Linear Accelerator (ORELA) to measure neutron total and capture cross sections of {sup 27}Al in the energy range from 100 eV to {approximately}400 keV. We report the resonance parameters as well as the Maxwellian average capture cross sections.
Date: August 30, 1999
Creator: Guber, K.H.; Harvey, J.A.; Hill, N.W.; Koehler, P.E.; Leal, L.C.; Sayer, R.O. et al.
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

Activation Measurements of High Energy Deuterons in the Plasma Focus Device

Description: Nuclear activation techniques were used to measure the fluence of high energy deuterons in a plasma focus device having a stored energy of 75 kilojoules at 18 kV. The $sup 12$C(d,n)$sup 13$N (330 keV threshold) and $sup 27$Al(d,p)$sup 28$Al reactions were used to provide both an absolute number of high energy deuterons and an average energy, evaluated from the $sup 13$N/$sup 28$Al ratio calculated for various energies by Young. Previous measurements indicated more than 10$sup 15$ deuterons could be accelerated to energies above 330 keV in the low pressure mode of operation, with a highly anisotropic distribution. Present measurements show that more than 10$sup 12$ deuterons achieve energies greater than 5 MeV on some high intensity shots in the low pressure mode. The presence of multi-MeV deuterons in the plasma focus device was substantiated by measuring activation as a function of depth in 1 mil Al foils, and by measurements of neutron energy using time-of-flight. (auth)
Date: December 1, 1975
Creator: Gullickson, R. L. & Sahlin, H. L.
Partner: UNT Libraries Government Documents Department

Recoil properties of $sup 11$C and $sup 18$F produced in the interaction of 1- to 11.5-GeV protons with $sup 27$Al. Progress report

Description: This work is a continuation of the recoil study of radioactive products from the proton bombardment of Al. Recoil properties of $sup 11$C and $sup 18$F are reported for proton energies of 1, 3, 6, and 11.5 GeV. Values of 2W(F+B) are tabulated and plotted. 2 figures, 4 tables (RWR)
Date: April 30, 1976
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

Advanced materials for aerospace and biomedical applications: New glasses for hermetic titanium seals

Description: Titanium and titanium alloys have an outstanding strength-to-weight ratio and corrosion resistance and so are materials of choice for a variety of aerospace and biomedical applications. Such applications are limited by the lack of a viable hermetic glass sealing technology. Conventional silicate sealing glasses are readily reduced by titanium to form interfacial silicides that are incompatible with a robust glass/metal seal. Borate-based glasses undergo a similar thermochemistry and are reduced to a titanium boride. The kinetics of this reactions, however, are apparently slower and so a deleterious interface does not form. Chemically durable lanthanoborate glasses were examined as candidate sealing compositions. The compositions, properties, and structures of several alkaline earth, alumina, and titania lanthanoborate glass forming systems were evaluated and this information was used as the basis for a designed experiment to optimize compositions for Ti-sealing. A number of viable compositions were identified and sealing procedures established. Finally, glass formation, properties, and structure of biocompatible Fe{sub 2}O{sub 3}- and TiO{sub 2}-doped calcium phosphate systems were also evaluated.
Date: November 1, 1996
Creator: Brow, R.K.; Tallant, D.R. & Crowder, S.V.
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

Neutron Yield Measurements via Aluminum Activation

Description: Neutron activation of aluminum may occur by several neutron capture reactions. Four such reactions are described here: {sup 27}Al + n = {sup 28}Al, {sup 27}Al(n,{alpha}){sup 24}Na, {sup 27}Al(n, 2n){sup 26}Al and {sup 27}Al(n,p){sup 27}Mg. The radioactive nuclei {sup 28}Al, {sup 24}Na, and {sup 27}Mg, which are produced via the {sup 27}Al + n = {sup 28}Al, {sup 27}Al(n,{alpha}){sup 24}Na and {sup 27}Al(n,p){sup 27}Mg neutron reactions, beta decay to excited states of {sup 28}Si, {sup 24}Mg and {sup 27}Al respectively. These excited states then emit gamma rays as the nuclei de-excite to their respective ground states.
Date: December 8, 1999
Partner: UNT Libraries Government Documents Department


Description: Fission product cross sections of (p,f)-reaction in thin samples of {sup 208}Pb, {sup nat}HgO, {sup nat}W irradiated with high-energy protons are measured. The irradiations were made using proton beams extracted from the ITEP synchrotron. The nuclide yields were {gamma}-spectrometered directly using a high-resolution Ge-detector. The GENIE2000 code was used to process the measured {gamma}-spectra and the ITEP-developed SIGMA code was used together with the PCNUDAT nuclear decay database to identify the {gamma}-lines and to determine the cross-sections. The {sup 27}Al(p,x){sup 22}Na reaction was used to monitor the proton flux. The LAHET, CEM2k, CEM95, CASCADE/INPE, CASCADE, INUCL, and YIELDX codes were used for computer simulation of the products measured. Comparison of simulated and experimental values shows insufficient predictive power of the existing fission models. The results obtained are of importance in studying the parameters of the Pb, Hg and W target modules of the hybrid Accelerator-Driven System (ADS) facilities.
Date: December 1, 2000
Creator: others], Y. TITARENKO
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

NMR and NQR study of the thermodynamically stable quasicrystals

Description: {sup 27}Al and {sup 61,65}Cu NMR measurements are reported for powder samples of stable AlCuFe and AlCuRu icosahedral quasicrystals and their crystalline approximants, and for a AlPdMn single grain quasicrystal. Furthermore, {sup 27}Al NQR spectra at 4.2 K have been observed in the AlCuFe and AlCuRu samples. From the quadrupole perturbed NMR spectra at different magnetic fields, and from the zero field NQR spectra, a wide distribution of local electric field gradient (EFG) tensor components and principal axis system orientations was found at the Al site. A model EFG calculation based on a 1/1 AlCuFe approximant was successful in explaining the observed NQR spectra. It is concluded that the average local gradient is largely determined by the p-electron wave function at the Al site, while the width of the distribution is due to the lattice contribution to the EFG. Comparison of {sup 63}Cu NMR with {sup 27}Al NMR shows that the EFG distribution at the two sites is similar, but that the electronic contribution to the EFG is considerably smaller at the Cu site, in agreement with a more s-type wave function of the conduction electrons.
Date: February 10, 1995
Creator: Shastri, A.
Partner: UNT Libraries Government Documents Department

NMR study of nanophase Al/Al-oxide powder and consolidated composites

Description: {sup 27}Al Nuclear Magnetic Resonance (NMR) measurements from aluminum powders and consolidated nanophase aluminum made from those powders are presented. The signals from the metal and surface oxidation are easily separated and are compared before and after consolidation. The results presented indicate that the oxide coating becomes the interface region within the nanophase composite material and that during consolidation the metal has undergone a deformation equivalent to that seen for bulk material under a compressive strain of between 4% and 8%.
Date: October 1, 1994
Creator: Suits, B. H.; Apte, P.; Wilken, D. E. & Siegel, R. W.
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