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in subjects: "Nuclear Fragments"

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Measurements of Non-Leptonic Weak Decays of Lambda Hypernuclei

Aspects of recent measurements of the mesonic and non-mesonic partial decay rates of {sub {Lambda}}{sup 5}He, and {sub {Lambda}}{sup 12}C are discussed. We comment on what the experiments tell us about the spin-isospin structure of {Delta}S=1 weak interaction in the nuclear environment. 14 refs., 1 fig.

Date: January 1, 1991

Creator: Schumacher, Reinhard A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Kaon-nucleus interactions

The recent progress in hypernuclear physics, in particular the studies of ..lambda.. and ..sigma.. states via the strangeness-exchange (K/sup -/,..pi../sup -/) reaction, are reviewed. Prospects for future investigations with (proposed) intense kaon beams are also evaluated, for instance the production of high spin hypernuclei via the (..pi../sup +/,K/sup +/) reaction, and the formation of strangeness S = -2 hypernuclei (..lambda lambda.. or Xi/sup -/) by means of the (K/sup -/,K/sup +/) process… more

Date: January 1, 1980

Creator: Dover, C B

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Measurement of energy deposited by charged-particle beams in composite targets

We have measured the energy deposited in two types of composite targets by a number of charged-particle beams: targets made of /sup 238/U, Lucite, and polyethylene were exposed to 0.26-GeV protons and 0.33-GeV deuterons, and aluminum-Lucite composites were exposed to 0.5-GeV electrons. In addition, we measured neutrons and gamma rays emitted from solid targets of various materials (including /sup 238/U and iron) exposed to 0.26-GeV protons and 0.33-GeV deuterons. We used passive detectors (ther… more

Date: July 2, 1980

Creator: Farley, E.; Becker, J.; Crase, K.; Howe, R. & Selway, D.

Item Type: Report

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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Average neutronic properties of prompt fission products

Calculations of the average neutronic properties of the ensemble of fission products producted by fast-neutron fission of /sup 235/U and /sup 239/Pu, where the properties are determined before the first beta decay of any of the fragments, are described. For each case we approximate the ensemble by a weighted average over 10 selected nuclides, whose properties we calculate using nuclear-model parameters deduced from the systematic properties of other isotopes of the same elements as the fission … more

Date: February 1, 1982

Creator: Foster, Jr. D. G. & Arthur, E. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Open problems in sub-barrier fusion

Two aspects of sub-barrier fusion are discussed. A challenge to the use of fission fragment angular distributions to probe the spin distribution in fusion is addressed. Evidence from excitation functions for the importance of neutron transfer and the neck degree of freedom is examined.

Date: January 1, 1992

Creator: Vandenbosch, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Light-particle emission as a probe of the rotational degrees of freedom in deep-inelastic reactions

The emission of alpha particles in coincidence with the most deeply inelastic heavy-ion reactions has been studied for /sup 181/Ta/sup +/ /sup 165/Ho at 1354 MeV laboratory energy and /sup nat/Ag + /sup 84/Kr at 664 MeV. Alpha particle energy spectra and angular distributions, in coincidence with a projectile-like fragment, were acquired both in the reaction plane and out of the reaction plane at a fixed in-plane angle. The in-plane data for both systems are employed to show that the bulk of th… more

Date: May 1, 1982

Creator: Sobotka, L.G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Studies of complex fragment emission in heavy ion reactions

This report discusses the following topics: High energy photon production in a HI collision; the mechanism for the disassembly of excited {sup 16}O projectiles into four alpha particles; the disassembly of excited {sup 28}Si projectiles; large pre-fission multiplicities from temperature; dependent friction and fission barriers; multiplicity correlations; molecular beam induced fusion; dwarf ball and wall; mini wall; and computer and local data acquisition systems.

Date: September 4, 1991

Creator: Charity, R.J. & Sobotka, L.G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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A = 4 0/sup +/ - 1/sup +/ binding-energy difference

The A = 4 ..lambda..-hypernuclei provide a rich source of information about the s-wave properties of the fundamental hyperon-nucleon (YN) force as well as offer a unique opportunity to investigate the complications that arise in calculations of the properties of bound systems in which one baryon (here the ..lambda..) with a given isospin couples strongly to another (the ..sigma..) with a different isospin. The ..lambda../sup 4/H - ..lambda../sup 4/He isodoublet ground-state energies are not con… more

Date: January 1, 1982

Creator: Gibson, B. F. & Lehman, D. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Neutron multiplicity measurements of Cf and Fm isotopes

Prompt neutrons in coincidence with the two fission fragments from the SF of californium 250, 252, and 254, and fermium 256 and 257 were measured with a 75-cm-diameter, Gd-loaded liquid scintillation counter having a neutron-detection efficiency of about 80%. The kinetic energies of both fission fragments and the number of neutrons for each fission event were recorded. From these data, the fragment masses and kinetic energies, the average number of neutrons per fission, and the neutron multipli… more

Date: January 1, 1977

Creator: Hoffman, D. C.; Ford, G. P.; Balagna, J. P. & Veeser, L. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Studies of the /sup 32/S + /sup 182/W reaction

Fission-like products from the reaction /sup 32/S + /sup 182/W were measured over the entire angular range from theta = 10-170/sup 0/ and for bombarding energies of E/sub lab/ = 166, 177, 222, and 260 MeV using an array of eight Si detectors. From the measured energy and flight time the product mass was determined event-by-event by performing the appropriate corrections for the plasma delay and pulse height defect associated with Si detectors. The mass, angular, and total kinetic energy distrib… more

Date: January 1, 1986

Creator: Back, B. B.; Keller, J. G.; Worsham, A.; Glagola, B. G.; Henderson, D.; Kaufman, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Role of rotational degrees of freedom in heavy-ion collisions

The degrees of freedom affected by the angular momentum are identified. The relevance of the equilibrium fluctuations in a diffusive evolution of the system is discussed. The statistical limit is described and chosen as a reference for comparing with experiment. The rigid rotation regime is shown to be reached in a variety of reactions. The fragment spin alignment is measured from ..gamma..-ray multiplicities and anisotropies as well as from sequential fission angular distributions. Good agreem… more

Date: April 1, 1982

Creator: Moretto, Luciano G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Fission-fragment-induced helium blistering of /sup 252/Cf-exposed surfaces

Inner surfaces of a Pt-10% Rh capsule exposed at room temperature to alpha particles and fission fragments in a large /sup 252/Cf source showed many small blisters, with elongated configurations in some areas. Formation of the blisters was attributed to the fission-fragment-induced agglomeration of helium implanted by the alpha particles, coupled with a stress relieving transport of lattice atoms displaced by the fission fragments into the blister walls. Lateral and vertical elongation of the b… more

Date: January 1, 1977

Creator: McDonnell, W.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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3-body final states in peripheral heavy-ion collisions: nuclear clustering structure and projectile excitation revisited

Even though peripheral heavy-ion collisions are less violent than their central counterparts, the large energy exchange between the reactants often leaves the primary products in excited particle-unstable states whose subsequent decay leads to 3 or more nuclei emerging in the final exit channel. These post-reaction, predominantly sequential de-excitation processes can sometimes provide interesting structural information about the parent nuclei. In fact, provided these processes are well underst… more

Date: February 1, 1986

Creator: Chan, Y.; Chavez, E.; Gazes, S.B.; Kamermans, R.; Schmidt, H.R.; Siwek-Wilczynska, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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In-pile intragranular densification of oxide fuels (AWBA Development Program)

This report proposes a model to describe in-pile densification of oxide fuels, by both vacancy boil-off due to thermal excitation and vacancy knockout by the passage of fission fragments through the pores. The model includes the migration rates of both vacancies and interstitials to pores and the production of vacancy-rich damage cascades by fission fragments. It has been coupled with a previously reported swelling and gas release model so that it can predict the total dimensional changes of th… more

Date: October 1977

Creator: Dollins, C. C. & Nichols, F. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Kaon-nucleus physics at low and medium energies

Topics discussed for the treatment of kaon--nucleus physics at low and intermediate energies include K/sup +/ and K/sup -/ interactions exotic resonances, anti KN amplitudes optical potential graphs, kaon wave function in /sup 12/C, energy levels in /sup 12/C hypernuclei, and possibility of stable light systems with S = -. (JFP)

Date: April 1, 1977

Creator: Dover, C. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Mechanism of light-particle emission

A general overview of the field of high-energy nuclear collisions studied from light particle spectra, pions, kaons, lambdas, protons, deuterons, and light composite fragments is given. Specifically, the basic reaction mechanism that determines the main features of particle emission such as the energy and angular distributions, the multiplicity, the production rate, the projectile and target mass dependences, the beam-energy dependences, etc. are discussed. Very general features of high-energy … more

Date: February 1, 1982

Creator: Nagamiya, S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Aspects of strangeness production with 15 -- 30 GeV proton beams

We discuss the spectrum of physics questions related to strangeness which could be addressed with a 15--30 GeV proton storage ring. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hyper-fragments in p-nucleus collisions, and hyperon spin observables in inclusive production.

Date: April 1, 1992

Creator: Dover, C. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mechanism of nuclear dissipation in fission and heavy-ion reactions

Recent advances in the theoretical understanding of nuclear dissipation at intermediate excitation energies are reviewed, with particular emphasis on a new surface-plus-window mechanism that involves interactions of either one or two nucleons with the moving nuclear surface and also, for dumbbell-like shapes encountered in fission and heavy-ion reactions, the transfer of nucleons through the window separating the two portions of the system. This novel dissipation mechanism provides a unified ma… more

Date: January 1, 1986

Creator: Nix, J. R. & Sierk, A. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Intermediate mass fragment emission from 8 to 40 MeV/u

Experimental data for fragmentation in the reactions /sup 93/Nb = /sup 9/Be, /sup 12/C, and /sup 27/Al are presented. Data were obtained from the LBL BEVALAC (25 to 40 MeV/u), GSI Unilac (11 to 18 MeV/u) and LBL SuperHILAC. These measurements imply, that over a large range of bombarding energies, intermediate mass fragments are produced by the bineary decay of a compound nucleus-like system. At low bombarding energies, these systems are associated with a complete fusion reaction, whereas for th… more

Date: February 1, 1986

Creator: Charity, R. J.; McMahan, M. A.; Bowman, D. R.; Liu, Z. H.; McDonald, R. J.; Wozniak, G. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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New directions in kaon-nucleus physics

The prospects for nuclear physics with kaons are reviewed including (1) elementary interactions k/sup +-/N; (2) K/sup +/-induced processes on nuclei; (3) resonance physics with K/sup -/ and ..pi../sup +-/ (greater than or equal to 1 GeV/c/); (4) neutral kaon interactions; and (5) hypernuclear physics. Summary of kaon beam requirements is given. (WHK)

Date: January 1, 1982

Creator: Dover, C. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Binding energies of hypernuclei and. lambda. -nuclear interactions

Variational Monte Carlo calculations have been made for the s-shell hypernuclei and also of /sup 9/Be hypernuclei with a 2..cap alpha.. + ..lambda.. model. The well depth is calculated variationally with the Fermi hypernetted chain method. A satisfactory description of all the relevant experimental ..lambda.. separation energies and also of the ..lambda..p scattering can be obtained with reasonable TPE ..lambda..N and ..lambda..NN forces and strongly repulsive dispersive ..lambda..NN forces whi… more

Date: January 1, 1985

Creator: Bodmer, A. R. & Usmani, Q. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Exchange of lyotropic series cations by micaceous vermiculite and its weathering products determined by electron microscopy and radiochemical analysis. Final technical report, June 1, 1965-October 31, 1978

Micaceous vermiculite was found to be ubiquitous in soils, sediments, and aerosol mineral dusts and to adsorb fission product ions, particularly /sup 137/Cs/sup +/ and /sup 90/Sr/sup 2 +/. Crystallographic wedge zones (imaged by ultramicrotomy and electron microscopy) in micaceous vermiculite effected tight fixation of Cs/sup +/. Lowering of mica layer charge occurred in local areas, electronoscopically imaged by use of blister-swelling cations. Nuclear fission particle tracks of U enhanced tra… more

Date: January 1, 1978

Creator: Jackson, M L

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Selected problems in experimental intermediate energy physics

The objectives of this research program are to: investigate forefront problems in experimental intermediate energy physics; educate students in this field of research; and, develop the instrumentation necessary to undertake this experimental program. Generally, the research is designed to search for physical processes which cannot be explained by conventional models of elementary interactions. This includes the use of nuclear targets where the nucleus provides a many body environment of strongl… more

Date: September 1, 1990

Creator: Mayes, B.W.; Hungerford, E.V. & Pinsky, L.S.

Item Type: Report

Partner: UNT Libraries Government Documents Department