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in subjects: "Nuclear Reactions"

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Particle identification in ultrarelativistic nuclear collisions

The role of particle identification (PID) in both fixed-target and colliding-beam studies of ultrarelativistic nuclear (URN) collisions is examined. The demands placed on the PID systems by peculiarities of URN collisions, such as large multiplicities and the need for simultaneous measurement of a number of observables, are discussed. A variety of PID techniques are reviewed, with emphasis on their applicability and efficiency in the environment of such collisions. Two examples of PID as incorp… more

Date: April 1, 1986

Creator: DiGiacomo, N.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Excitation of giant resonances via direct reactions

Experimental measurements of electric giant multipole resonances are discussed. The parameters of the giant quadrupole resonance are now firmly established by an extensive set of measurements. The GQR is providing a significant influence in other areas of nuclear physics. The monopole resonance has now been established and its observation has provided the first direct measure of the nuclear compressibility. A strong case for the existence of a giant octupole resonance is now being made through … more

Date: January 1, 1982

Creator: Bertrand, F.E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Proceedings of the LAMPF workshop on physics with polarized nuclear targets

Topics of discussion included static and dynamic methods for polarizing nuclei, proton and pion nucleus scattering experiments, and possible future experiments at LAMPF. Separate abstracts were prepared for 11 papers in this report. (DWL)

Date: August 1, 1986

Creator: Burleson, G.; Gibbs, W.; Hoffmann, G.; Jarmer, J. J. & Tanaka, N. (eds.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Fifth high-energy heavy-ion study

This was the fifth of a continuing series of summer studies held at LBL to discuss high energy heavy ion collisions. Recently, a similar meeting has been held on alternate years at GSI (Darmstadt); and, in 1979, we held a meeting at LBL exclusively devoted to ultra-relativistic nuclear collisions. Two new features distinguish this study from earlier meetings in the series. First, the energy range for discussion was broadened by including collisions from about 20 MeV/nucleon to the highest avail… more

Date: October 1, 1981

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The (t,d) reaction on the Ni isotopes with polarized tritons

The (t vector,d) reaction has been measured on targets of /sup 58/ /sup 60/ /sup 62/ /sup 64/Ni with 17 MeV polarized tritons. Spectroscopic factors, angular momentum and total spin transfer were obtained from the differential cross section and A/sub y/ values of levels up to 3.5 MeV in excitation energy. The present (t,d) measurement enables a better description of the 9/2/sup +/ and 5/2/sup +/ states which show significant shell crossing effects as a function of increasing neutron number.

Date: January 1, 1980

Creator: Flynn, E. R.; Cizewski, J. A.; Brown, R. E.; Hardekopf, R. A. & Sunier, J. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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/sup 16/O + /sup 40/Ca inelastic scattering and the elastic scattering wave function

The /sup 16/O + /sup 40/Ca inelastic scattering has been measured at 60-MeV incident energy, and evidence has been found in support of an explicit coupling between direct and elastic channels. The measurements were extended over a large angular range and in particular to very forward angles. The ratio of cross sections between extreme forward and backward angles proved very useful in studying the underlying reaction mechanism.

Date: January 1, 1977

Creator: Rehm, K.E.; Henning, W.; Erskine, J.R. & Kovar, D.G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Di-leptons at the Bevalac

Recent results on the production of di-leptons measured by the Di-Lepton-Spectrometer (DLS) collaboration are discussed. Results are reported from observations made on p /plus/ Be collisions with proton beams from 1.0 to 4.9 GeV and on Ca collisions with calcium beams of 1.0 to 2.0 GeV/A. The shape of the distributions are similar to that at higher energies. The low mass cross section appears to be explained by ..pi..-..pi.. annihilation, but detailed calculations are needed to substantiate tha… more

Date: March 1, 1988

Creator: Matis, H.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Neutron environment in d + Li facilities

A microscopic d + Li neutron yield model has been developed based upon classical models and experimental data. Using equations suggested by the Serber and evaporation models, a generalized least squares adjustment procedure generated angular yields for E/sub d/ to 40 MeV using the available experimental data. The HEDL-UCD experiment at E/sub d/ = 35 was used to adjust parameters describing the neutron spectra. The model is used to predict yields, spectra, and damage responses in the FMIT Test C… more

Date: January 1, 1980

Creator: Mann, F. M.; Schmittroth, F. & Carter, L. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Selective population of high-j states via heavy-ion-induced transfer reactions

One of the early hopes of heavy-ion-induced transfer reactions was to populate states not seen easily or at all by other means. To date, however, I believe it is fair to say that spectroscopic studies of previously unknown states have had, at best, limited success. Despite the early demonstration of selectivity with cluster transfer to high-lying states in light nuclei, the study of heavy-ion-induced transfer reactions has emphasized the reaction mechanism. The value of using two of these react… more

Date: January 1, 1982

Creator: Bond, P.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Irradiation experiment for lithium ceramics

Solid breeder materials are required in D-T fusion reactor blankets to convert fusion neutrons to tritium and thermal energy while providing some neutron shielding for the magnets. Lithium compounds such as Li/sub 2/O, LiAlO/sub 2/, Li/sub 4/SiO/sub 4/ and Li/sub 2/ZrO/sub 3/ have been proposed as solid breeder materials. Tritium is necessary to maintain the fuel supply for the D-T fusion reaction. No high burnup irradiation performance data is available for these materials in a neutron environ… more

Date: March 1, 1982

Creator: Hollenberg, G.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Source-jerk analysis using a semi-explicit inverse kinetic technique

A method is proposed for measuring the effective reproduction factor, k, in subcritical systems. The method uses the transient response of a subcritical system to the sudden removal of an extraneous neutron source (i.e., a source jerk). The response is analyzed using an inverse kinetic technique that least-squares fits the exact analytical solution corresponding to a source-jerk transient as derived from the point-reactor model. It has been found that the technique can provide an accurate means… more

Date: January 1, 1985

Creator: Spriggs, G.D. & Pederson, R.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Pacific Northwest Laboratory Report on Fusion Energy Research, April 1977 - June 1977

The development of economic data for fusion power plants continued in a study estimating the potential impact of a shortage of materials important in fusion plant construction. In studies developing heat transfer and fluid flow design tools for fusion reactor blankets, preconceptual design studies were initiated to identify the potential design limits of water cooling in the first wall of Tokamak Next Step (TNS) concepts. In surface effects research clean gold samples were irradiated in the Uni… more

Date: July 1, 1977

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Fast-neutron total and scattering cross sections of elemental palladium

Neutron total cross sections of palladium are measured from approx. = 0.6 to 4.5 MeV with resolutions of approx. = 30 to 70 keV at intervals of less than or equal to 50 keV. Differential neutron elastic- and inelastic-scattering cross sections are measured from 1.4 to 3.85 MeV at intervals of 50 to 100 keV and at 10 to 20 scattering angles distributed between approx. = 20 and 160/sup 0/. The experimental results are compared with respective quantities given in ENDF/B-V and used to deduce an opt… more

Date: June 1, 1982

Creator: Smith, A. B.; Guenther, P. T. & Whalen, J. F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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What can HELIOS tell us on phase transition of nuclear matter

Transverse energy (E/sub t/) distributions and P/sub t/ spectra of negative particles and photons measured by the HELIOS experiment in 200 GeVN and 60 GeVN oxygen-nucleus reactions are presented. The E/sub t/ distributions are compared to a geometrical parametrization and a Montereverse arrowCarlo calculation, particle spectra to the proton-nucleus reaction case. The comparisons show that yet the results can be understood without assuming quark-gluon plasma formation. A discussion is made based… more

Date: January 1, 1987

Creator: En'yo, H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Pseudorapidity distributions and correlations in central sup 16 O interactions at 200 A GeV

Whether or not adequate energy densities for a transition to the Quark-Gluon Plasma (QGP) phase are possible in {sup 16}O and {sup 32}S induced reactions is still an open question. Before unambiguous signals can be identified it is necessary to understand the background upon which the expected QGP signatures can be sought. An important aim of early experiments in this new energy density regime is thus to understand the process of hadronization in a nuclear environment. In any discussion of high… more

Date: January 1, 1988

Creator: Wilkes, R. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Physics of antimatter-matter reactions for interstellar propulsion

At the stage of the antiproton-nucleon annihilation chain of events relevant to propulsion the annihilation produces energetic charged pions and gamma rays. If annihilation occurs in a complex nucleus, protons, neutrons, and other nuclear fragments are also produced. The charge, number, and energy of the annihilation products are such that annihilation rocket engine concepts involving relatively low specific impulse (I/sub sp/ approx. = 1000 to 2000 s) and very high I/sub sp/ (3 x 10/sup 7/ s) … more

Date: August 22, 1986

Creator: Morgan, D.L. Jr.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Radiation-induced segregation in HT-9 martensitic steel

Miniature notched-bar specimens of normalized and tempered HT-9 were neutron irradiated to approx.13 dpa and broken at liquid nitrogen temperatures in a UHV chamber. Fracture surfaces were analyzed using scanning Auger electron spectroscopy. Following irradiation at 410/sup 0/C, the fracture surface contained a small number of large relatively smooth facets, which are thought to be prior austenite grain boundaries. Strong segregation of Ni, Cr, Si, and P was detected at these surfaces, the rema… more

Date: January 1, 1986

Creator: Clausing, R.E.; Heatherly, L.; Faulkner, R.G.; Rowcliffe, A.F. & Farrell, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Status of the translawrencium elements (Z > 103)

As a result of conflicting claims to the discovery of the trans-lawrencium elements (Z > 103), IUPAC's Inorganic Chemistry Nomenclature Commission, (II.2), has been incapable of coming to a decision on rightful discoverer for these elements. In addition, the Atomic Weights Commission, (II.1), has from time to time been interested in the status of the search for the superheavy elements, i.e., those elements which might be found in the vicinity of the 'island of stability'. Theoretical studies ha… more

Date: January 1, 1985

Creator: Holden, Norman E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Statistical fluctuations in heavy-ion collisions

The relevance of the statistical equilibrium limit to the description of substantially relaxed degrees of freedom is discussed. Fluctuations are considered specifically in the following processes: the correlation between entrance-channel angular momentum and exit-channel kinetic energy; the sharing of the dissipated kinetic energy between the two fragments; the magnitude and the alignment of the fragment angular momentum including the effect of shell structure. It is found that statistical fluc… more

Date: February 1, 1982

Creator: Moretto, Luciano G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Fractional processes and nuclear disassembly in very-heavy-ion collisions in the Fermi energy regime

Exclusive measurements of charged products and neutrons were performed for the reactions {sup 197}Au + (29 MeV/u) {sup 208}Pb and {sup 209}Bi + (28.2 MeV/u) {sup 136}Xe. The multiplicities of neutrons and charged particles are found to indicate collision impact parameters with different sensitivities. Characteristic correlations observed between massive products and light particles suggest the dominance of the damped-reaction mechanism in the Fermi energy domain. For central collisions, massive… more

Date: January 1, 1991

Creator: Schroeder, W.U.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Sensitivity of primary knock-on atom spectra and displacement per atom cross sections to different secondary neutron energy and angular distributions and ''in-group'' weighting schemes

The sensitivity of primary knock-on atom (PKA) spectra and displacement per atom (DPA) cross sections to different secondary neutron energy and angular distributions and ''in-group'' weighting schemes is investigated. It is shown that the sensitivity of the PKA spectra and DPA cross sections for the (n,n' unresolved) and (n,2n) reactions in Fe to different angular distributions and the same secondary neutron spectrum is reasonably large (approximately 15%), whereas the … more

Date: January 1, 1978

Creator: Gabriel, T. A. & Bishop, B. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Research in theoretical nuclear physics

The work done during the past year covers three separate areas, low energy nuclear reactions intermediate energy physics, and nuclear structure studies. This manuscript summarizes our achievements made in these three areas.

Date: October 1, 1991

Creator: Udagawa, T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Mechanism of (n,. gamma. ) reaction at low neutron energies

We discuss the interplay between direct capture, valence capture, and compound-nuclear capture in attempting to explain the vast amount of capture data for light-mass nuclei. 13 refs.

Date: January 1, 1991

Creator: Raman, S. (Oak Ridge National Lab., TN (United States)) & Lynn, J.E. (Los Alamos National Lab., NM (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Background radiation from fission pulses

Extensive source terms for beta, gamma, and neutrons following fission pulses are presented in various tabular and graphical forms. Neutron results from a wide range of fissioning nuclides (42) are examined and detailed information is provided for four fuels: /sup 235/U, /sup 238/U, /sup 232/Th, and /sup 239/Pu; these bracket the range of the delayed spectra. Results at several cooling (decay) times are presented. For ..beta../sup -/ and ..gamma.. spectra, only /sup 235/U and /sup 239/Pu result… more

Date: May 1, 1988

Creator: England, T. R.; Arthur, E. D.; Brady, M. C. & LaBauve, R. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department