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INVESTIGATION OF THE (10B,6Li* (3+, 2.18 MeV)) REACTION AS A METHOD FOR alpha-CLUSTER TRANSFER STUDIES

Description: The four-nucleon transfer reaction {sup 12}C({sup 10}B, {sup 6}Li*(2.18 MeV)) {sup 16}O has been studied at 68 MeV by coincidence measurement of the d + {alpha} breakup particles. The reaction is quite selective as is observed in other established {alpha}-transfer reactions.
Date: July 1, 1980
Creator: Bice, A.N.; Shotter, A.C.; Stahel, D.P. & Cerny, J.
Partner: UNT Libraries Government Documents Department

NEUTRON-CHARGED PARTICLE REACTIONS. THE ANALYSIS OF THIN LITHIUM AND BORON FILMS

Description: Thin Li/sup 6/F and B/sub 2/O/sub 3/ films were nondestructively analyzed by bombarding them with neutrons, obtaining the pulseheight distribution of the resultant charged particles, and determinlng the number of reactions from the area under each peak in the spectrum. The results agreed within the precision of this method with results of a flame analysis. This method is more accurate and sensitive than conventional neutron activation methods. (D.C.W.)
Date: January 1, 1962
Creator: Finston, H.L.; Wellwart, Y. & Bishop, W.
Partner: UNT Libraries Government Documents Department

Probing the nuclear medium with the K{sup +} meson

Description: Elastic differential cross sections for K{sup +} mesons scattered from targets of carbon and {sup 6}Li have been measured at an incident momentum of 715 MeV/c. The ratios of scattering cross sections from these targets are not predicted by theory, and are consistent with earlier suggestions that the K{sup +}-nucleon interaction is modified in the nuclear medium.
Date: December 31, 1995
Creator: Chrien, R.E.
Partner: UNT Libraries Government Documents Department

Microscopic calculation of {sup 6}Li elastic and transition form factors

Description: Variational Monte Carlo wave functions, obtained from a realistic Hamiltonian consisting of the Argonne {nu}{sub 18} two-nucleon and Urbana-IX three-nucleon interactions, are used to calculate the {sup 6}Li ground-state longitudinal and transverse form factors as well as transition form factors to the first four excited states. The charge and current operators include one- and two-body components, leading terms of which are constructed consistently with the two-nucleon interaction. The calculated form factors and radiative widths are in good agreement with available experimental data.
Date: July 1, 1998
Creator: R. B. Wiringa, R. Schiavilla
Partner: UNT Libraries Government Documents Department

Design and analysis of the lithium target system for the International Fusion Materials Irradiation Facility (IFMIF)

Description: Three lithium target design options are being evaluated for the IFMIF. The impact of various requirements on material selection, lifetime, operation and maintenance are discussed. Analysis for the free jet option is presented. Key aspects include jet stability, thermal and nuclear responses.
Date: September 1, 1995
Creator: Hua, T.; Smith, D.; Hassanein, A. & Gomes, I.
Partner: UNT Libraries Government Documents Department

THE FAST MULTIPLICATION EFFECT OF BERYLLIUM OXIDE IN REACTORS

Description: The net multiplication effect of beryllium oxide, which is due to the (n,2n) reaction, was calculated using an essentially exact calculation of the neutron spectrum as a function of energy. The upper limit of the (n,2n) cross section curve gives the unpoisoned value epsilon /sup +/ = 1.047 and the lower limit gives epsilon /sup -/ = 1,027. The behavior of the Li/sup 6/poisoned fast multiplication effect as a function of the number of collisions was studied for both beryllium and beryllium oxide. (auth)
Date: December 14, 1959
Creator: Hafele, W. & Tsagaris, M.
Partner: UNT Libraries Government Documents Department

In Situ Mercury Stabilization (ISMS) Treatment: Technology Maturation Project Phase I Status Report

Description: Mercury (Hg) was used to separate lithium-6 isotope for weapons production at the Y-12 Plant in Oak Ridge in the 1950s and 1960s. As much as two million pounds of elemental mercury was 'lost' or unaccounted for and a large portion of that material is believed to have entered the environment. The DOE site office in Oak Ridge has identified Hg pollution in soils, sediments, and streams as the most significant environmental challenge currently faced. In industry, large amounts of mercury have been used to manufacture products (e.g., fluorescent light bulbs, thermometers) and for chemical processing (e.g., production of chlorine and alkali via mercury electrochemical cells) and many of these industrial sites are now polluted with mercury contaminated soil as a result of previous releases and/or inadvertent leaks. Remediation techniques for Hg contaminated soils are either based on thermal desorption and recovery of the mercury or excavation and shipping of large volumes of material to remote facilities for treatment and disposal. Both of these alternatives are extremely costly. The Brookhaven National Laboratory (BNL) Environmental Research & Technology Division (ERTD) has demonstrated, in laboratory-scale experiments, the viability of treating mercury contaminated soils by means of sulfide treatment rods inserted into the soil through a process known as In Situ Mercury Stabilization (ISMS). This approach is partly based on BNL's patented and successfully licensed ex situ process for Hg treatment, Sulfur Polymer Stabilization/Solidification (SPSS) which converts Hg to the more stable sulfide form. The original experiments showed that Hg homogeneously distributed in soil rapidly migrates to form a high concentration zone of chemically stable mercuric sulfide near the treatment rods while concentrations of Hg in surrounding areas away from the treatment rods are depleted to acceptable levels. BSA has subsequently filed for patent protection on the ISMS technology. If further developed it ...
Date: March 1, 2008
Creator: Kalb,P.D. & Milian, L.
Partner: UNT Libraries Government Documents Department

Determination of Li$xup 6$ in Aqueous Solution by Neutron Activation Analysis

Description: A method for determining the concentration of Li/sup 6/ in aqueous solution was tested using the nuclear reactions Li/sup 6/(n, alpha )H and O/sup 16/(H/sup 3/,n)F/sup 18/. Annihilation gamma radiation of induced 1.87-hr F/ sup 18/ radioactivity was counted with a welltype scintillation counter, and the radioactivity per millimole of lithium was found to be independent of lithium concentration below about 0.2 moles/liter. The sensitivity limit for detecting lithium is less than 0.1 micromole (0.0075 micromole Li/sup 6/). (auth)
Date: July 10, 1959
Creator: Winchester, J. W.; Bate, L. C. & Leddicotte, G. W.
Partner: UNT Libraries Government Documents Department

Additional results concerning cross-section sensitivity of tritium breeding in a fusion reactor blanket: $sup 6$Li, $sup 7$Li, and $sup 93$Nb

Description: Previous work concerning cross-section sensitivity of the tritium breeding ratio showed ine effects of altering a partial cross section independently of other partial cross sections, permitting the total cross section to rise or fall. The results reported here are mostly for variations made while keeping the total cross section constant. The cases considered were for high and low values of the cross sections for /sup 6/Li(n, )t,/sup 7/Li(n, n' alpha )t, and for /sup 93/Nb(n2n) with compensatory changes in other cross sections. The general conclusions of previous work have been borne out both qualitatively and quantitatively under the present more realistic ground rules. In addition, results are reported for a modified CTR benchmark which has blanket material in place of the graphite reflector. This case shows a drop of 0.13 in /sup 6/Li productions, a rise of 0.02 in /sup 7/Li productions, and an increase of 0.15 in neutron leakage. (auth)
Date: January 1, 1974
Creator: Tobias, M. & Steiner, D.
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

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

A six-body calculation of the alpha-deuteron radiative capture cross section

Description: The authors have computed the cross section for the process d + alpha -> {sup 6}Li + gamma at the low energies relevant for primordial nucleosynthesis and comparison with laboratory data. The final state is a six-body wave function generated by the variational Monte Carlo method from the Argonne v-18 and Urbana IX potentials, including improved treatment of large-particle-separation behavior. The initial state is built up from the alpha-particle and deuteron ground-state solutions for these potentials, with phenomenological descriptions of scattering and cluster distortions. The dominant E2 cross section is in reasonable agreement with the laboratory data. Including center-of-energy and other small corrections, the authors obtain an E1 contribution which is larger than the measured contribution at 2 MeV by a factor of three. They calculate explicitly the impulse-approximation M1 contribution, which is expected to be very small, and obtain a result consistent with zero. They find little reason to suspect that the cross section is large enough to produce significant {sup 6}Li in the big bang.
Date: September 1, 2000
Creator: Nollett, K. M.; Wiringa, R. B. & Schiavilla, R.
Partner: UNT Libraries Government Documents Department

Low energy proton capture in light nuclei. Progress report, September 1, 1993--June 8, 1994

Description: Radiative capture reactions with light nuclei are of special interest in nuclear astrophysics because of their importance in the formation of the various elements. In many cases a simple direct-capture model that considers only the electromagnetic interaction is sufficient to reproduce experimental results. A direct-semidirect process may be used in which the transition amplitude is the sum of a direct term and another term representing the excitation of the target nucleus into a collective state. In cases where these approaches are not sufficient, the relative simplicity of nuclear systems with small numbers of fundamental particles allows microscopic calculations of measurable quantities from nucleon-nucleon potentials, using the multichannel resonating group model or, in some cases, Faddeev calculations. In the summer of 1990, the PI began a collaboration with Professor Henry Weller`s group at the Triangle Universities Nuclear Laboratory (TUNL). Weller`s group has studied radiative capture reactions with polarized beams at TUNL for over a decade, developing considerable expertise in the detection of high energy gamma rays and for the analysis of the measurements. The PI has been involved in the development of a new series of experiments at beam energies below 100 keV, using the positive beam directly from the high intensity atomic beam polarized ion source. This work is the topic of the present grant, which began September 1, 1993. The main activity in the grant occurs during the summer months. Since this is the first year of the grant, most of that activity will be during the upcoming summer months. The PI will travel to TUNL in mid-June and will spend most of his time from then through August either at TUNL or working on data reduction and other calculations at West Georgia College. The PI is moving from West Georgia College (WGC) to North Georgia College (NGC) in ...
Date: June 1, 1995
Creator: Prior, R.M.
Partner: UNT Libraries Government Documents Department

Femtometer toroidal structures in nuclei

Description: The two-nucleon density distributions in states with isospin T=0, spin S=1 and projection M{sub S}=0 and {+-}1 are studied in {sup 2}H, {sup 3,4}He, {sup 6,7}Li and {sup 16}O. The equidensity surfaces for M{sub S}=0 distributions are found to be toroidal in shape, while those of M{sub S}={+-}1 have dumbbell shapes at large density. The dumbbell shapes are generated by rotating tori. The toroidal shapes indicate that the tensor correlations have near maximal strength at r < 2 fm in all these nuclei. They provide new insights and simple explanations of the structure and electromagnetic form factors of the deuteron, the quasi-deuteron model, and the dp, dd and {alpha}d L=2 (D-wave) components in {sup 3}He, {sup 4}He and {sup 6}Li. The toroidal distribution has a maximum-density diameter of {approximately}1 fm and a half-maximum density thickness of {approximately}0.9 fm. Many realistic models of nuclear forces predict these values, which are supported by the observed electromagnetic form factors of the deuteron, and also predicted by classical Skyrme effective Lagrangians, related to QCD in the limit of infinite colors. Due to the rather small size of this structure, it could have a revealing relation to certain aspects of QCD.
Date: March 1, 1996
Creator: Forest, J.; Pandharipande, V.; Pieper, S.; Wiringa, R.B.; Shiavilla, R. & Arriaga, A.
Partner: UNT Libraries Government Documents Department

THE STORY OF SIGMA HYPERNUCLEI - A MODERN FABLE.

Description: The reality of {Sigma} hypernuclei has been the subject of intense concern among experimenters and theoreticians for more than 20 years. The possible existence of {Sigma} hypernuclei was first suggested by a pioneering experiment on a {sup 9}Be target at the CERN PS. There were reported to be two narrow ({Gamma} < 8 MeV) peaks in the continuum region. This finding was quite unexpected since the widths of {Sigma} states were believed to be large due to the strong conversion process. It is obvious that if such relatively long-lived systems were confirmed unambiguously by experiment, their masses and widths provide important constraints on the {Sigma}N effective interaction and its relation to the {Lambda}N and NN interactions. Since the {Sigma} carries isospin, the role of isospin and isospin conservation in hadronic reactions could be explored. This report stimulated a number of subsequent experiments at the BNL-AGS and KEK, along with further experiments with a specially created short kaon beam at the CERN PS. Experimental data were reported for different targets at different momenta and at different conditions. Various tagging techniques were employed to suppress backgrounds, but always at the expense of a reduction in statistical quality. Because of problems with resolution and statistics, contradictions among the different sets of data resulted more often in clouding the issues than clarifying them. Thus, up until a few years ago, there was no statistically clear confirmation of this surprising finding. In the last few years, however, a series of definitive experiments has been performed at the BNL-AGS in an effort to resolve the discrepancies and settle the controversy. Besides repeating the initial experiment on Be, a target of {sup 6}Li was run. The earlier stopped kaon data on {sup 4}He was repeated in an in-flight experiment, and the suggestion of a {Sigma} bound state, ...
Date: February 19, 1999
Creator: CHRIEN,R.E.
Partner: UNT Libraries Government Documents Department