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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

Measurement of recoil polarization in the {sup 16}O(e,e'p) reaction.

Description: The longitudinal and transverse components of the polarization of the outgoing proton were measured for the reaction {sup 16}O(e,e'p) at a four-momentum transfer squared of 0.8 GeV{sup 2} in quasifree kinematics. These were the first measurements of polarization transfer observables for a complex nucleus. Comparison of the ratio of the transverse and longitudinal polarization to theoretical predictions allows the study of modification of the proton's form factors in the nuclear medium.
Date: July 1, 1999
Creator: Jones, Mark
Partner: UNT Libraries Government Documents Department

Gep/Gmp for Bound Protons: First Results for {sup 16}O with the Recoil Polarization Technique

Description: The first (e, e{prime}p) polarization transfer measurements on a heavy nucleus have been made at TJNAF. The reaction {sup 16}O(e, e{prime}p) was used to study the transfer of polarization to the recoil proton in quasielastic kinematics. The preliminary data are in good agreement with standard calculations which assume no modification of the nucleon form factors in the nuclear medium.
Date: May 1, 1999
Creator: Collaboration, Charles Glashausser for the Hall A
Partner: UNT Libraries Government Documents Department

Antisymmetrization effects in heavy-ion potentials and their dependence on the nucleon--nucleon interaction

Description: Double-folding heavy-ion potentials are conventionally generated by folding the densities of projectile and target with a nucleon--nucleon interaction. The success of the folding method has recently been explained by Fleckner and Mosel (Nucl. Phys. A277, 170 (1977)) in terms of a cancellation effect between two types of approximations, namely, the effects of neglecting the antisymmetrization between the ions and the polarization of the densities due to the (Coulomb and nuclear) forces between the ions. The validity of the above justification of folding potentials was here investigated by studying distortion and antisymmetrization effects in the heavy-ion interaction energy for a number of different nucleon--nucleon interactions. In particular, the change in the energy expectation value induced by neglecting the antisymmetrization between both ions, the sign of that change, and its sensitivity to the strength, range, and exchange terms of the nucleon--nucleon interaction chosen were examined. Calculations were done for the /sup 16/O + /sup 16/O system. It was found that a general statement about the effect of the antisymmetrization on the heavy-ion interaction energy cannot be made. For some nucleon--nucleon forces the energy increases; for others, it decreases. The magnitude and sign of the net effect depend very sensitively on the range, strength, and exchange terms of the nucleon--nucleon potential. In some cases the errors induced by neglecting antisymmetrization and polarization add rather than cancel. Thus, folding potentials cannot generally be justified in terms of a cancellation of the two approximations. 1 table. (RWR)
Date: October 1, 1977
Creator: Schultheis, H. & Schultheis, R.
Partner: UNT Libraries Government Documents Department

R-Matrix Evaluation of 160 Neutron Cross Sections up to 6.3 MeV

Description: We have evaluated {sup 16}O neutron cross sections in the resolved resonance region with the multilevel Reich-Moore code SAMMY. Resonance parameters were determined by a consistent analysis, including both Doppler and resolution broadening effects. To properly treat the {alpha} particle exit channel, an algorithm to calculate charged particle penetrabilities and shifts was incorporated into SAMMY.
Date: October 25, 2001
Creator: Sayer, R.O.
Partner: UNT Libraries Government Documents Department

The reaction dynamics of the {sup 16}O(e,e{prime}p) cross section at high missing energies

Description: The authors measured the cross section and response functions (R-L, R-T, and R-LT) for the {sup 16}O(e,e{prime}p) reaction in quasielastic kinematics for missing energies 25 <= E-miss <= 120 MeV at various missing momenta P-miss <= 340 MeV/c. For 25 < E-miss < 50 MeV and P-miss approx 60 MeV/c, the reaction is dominated by single-nucleon knockout from the 1s1/2-state. At larger P-miss, the single-particle aspects are increasingly masked by more complicated processes. For E-miss > 60 MeV and P-miss > 200 MeV/c, the cross section is relatively constant. Calculations which include contributions from pion exchange currents, isobar currents and short-range correlations account for the shape and the transversity but only for half of the magnitude of the measured cross section.
Date: September 1, 2000
Creator: Jefferson Lab Hall A Collaboration: N. Liyanage, et alia
Partner: UNT Libraries Government Documents Department

R-Matrix Evaluation of {sup 16}O neutron cross sections up to 6.3 MeV

Description: In this paper the authors describe an evaluation of {sup 16}O neutron cross sections in the resolved resonance region with the multilevel Reich-Moore R-matrix formalism. Resonance analyses were performed with the computer code SAMMY [LA98] which utilizes Bayes' method, a generalized least squares technique.
Date: August 1, 2000
Creator: Sayer, R.O.; Leal, L.C.; Larson, N.M.; Spencer, R.R. & and Wright, R.Q.
Partner: UNT Libraries Government Documents Department

Relativistic mean-field theories and nuclear properties

Description: The nucleus is described as consisting of relativistic nucleons and explicit mesonic degrees-of-freedom which are considered to be the relativistic generalization of the Skyrme force. The meson-parameters can be adjusted such that the model gives an excellent description of spherical nuclear ground states, first axially symmetric deformed calculations are presented. Dynamic calculations of relativistic /sup 16/O-/sup 16/O scattering are also done; they show pronounced effects of the mesonic degrees-of-freedom. 24 refs., 3 figs., 3 tabs.
Date: January 1, 1986
Creator: Reinhard, P.G.; Rufa, M.; Fink, J.; Maruhn, J.; Stoecker, H.; Greiner, W. et al.
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

EFFECT OF DENSELY IONIZING RADIATIONS ON DRY PREPARATIONS OF LYSOZYME, TRYPSIN, AND DNase

Description: The effects of beams of protons and alpha particles from the 60-inch cyclotron and beams of accelerated nuclei of heliuan-4, carbon-12, oxygen-16, and neon-20 from the linear accelerator on thin films of dried enzymes were measured. The experimental apparatus is described and results are presented graphically. (C.H.)
Date: August 1, 1958
Creator: Brustad, T.
Partner: UNT Libraries Government Documents Department

Polaronic signatures in phonon isotopic shifts

Description: The effect of O(16) by O(18) isotopic substitution in the excitation spectrum of a model electron-phonon Hamiltonian, previously used to describe the dynamics of the O(4)-Cu(1)-O(4) cluster in YBa{sub 2}Cu{sub 3}O{sub 7}, is presented. This model includes electronic correlations and electron-phonon interactions, exhibiting the presence of polaron tunneling. The calculated isotopic shifts of phonon excitations differ from those found using harmonic or anharmonic potentials, and are consistent results of optical measurements of c-axis phonons. The isotopic substitution changes the dynamics of polaron tunneling and produces a change in the local structure.
Date: December 31, 1998
Creator: Mustre de Leon, J.; Coss, R. de; Rubio-Ponce, A.; Bishop, A.R. & Trugman, S.A.
Partner: UNT Libraries Government Documents Department

{sup 16}O neutron cross section evaluation

Description: This work has resulted from a need to compute more accurately the neutron scattering cross sections and angular distributions for {sup 16}O. Several oxygen evaluations have been performed in the past with R-Matrix theory, including ENDF/B-V and ENDF/B-VI. ENDF/B-VI is an improvement over ENDF/B-V, but still underpredicts in general the forward scattering of neutrons below 2.5 MeV. R-Matrix theory is used in describing cross sections at and near the resonance energies; but may not always be adequate in describing cross sections between resonances, especially when they are widely spaced. The optical (potential well) model of the nucleus is very good in representing cross sections that vary smoothly with energy, but not at describing all of the detailed resonance cross sections. A combination of the potential well model and R-Matrix theory was used for this work to represent cross sections with isolated resonances with large spacings between them. The total neutron cross section of oxygen-16 below 3.0 MeV has widely separated resonances and a dip in the cross section at 2.35 MeV. In the vicinity of resonances, where cross sections vary rapidly with energy, R-Matrix theory has been successful in fitting experimental data. In the region between resonances, an analytical procedure with physical basis is needed that agrees with data over a wide range of energies bracketing regions where experimental measurements are lacking.
Date: June 1, 1998
Creator: Caro, E.
Partner: UNT Libraries Government Documents Department

Rapid increase in prescission GDR {gamma}-ray emission with energy

Description: A rapid increase in the emission of prescission giant dipole resonance (GDR) {gamma}-rays with bombarding energy is observed in excited Th and Cf nuclei formed in the reactions {sup 16}O+{sup 20B}Pb and {sup 32}S+{sup nat}W,{sup 208}Pb. This increase begins around E{sub exc} = 40 MeV for the {sup 16}O+{sup 208}Pb reaction and E{sub exc} = 70 MeV for the {sup 32}S-induced reactions. The excess {gamma}-ray yield above these thresholds cannot be described within the standard statistical model. Statistical model calculations which include a temperature dependent nuclear dissipation are able to reproduce simultaneously the observed GDR {gamma}-ray spectra and recently measured evaporation residue across sections.
Date: December 31, 1995
Creator: Hofman, D.J.; Back, B.B. & Paul, P.
Partner: UNT Libraries Government Documents Department

A new 14 GHz Electron-Cyclotron-Resonance Ion Source (ECRIS) for the Heavy Ion Accelerator Facility ATLAS

Description: A new 14 GHz Electron-Cyclotron-Resonance Ion Source (ECRIS) has been designed and built over the last two years. The source, which is a modification of the AECR at Berkeley, incorporates the latest results from ECR developments to produce intense beams of highly charged ions, i.e. an improved magnetic confinement of the plasma electrons. The aluminum plasma chamber and extraction electrode as well as a biased disk on axis at the microwave injection side donate additional electrons to the plasma, making use of the large secondary electron yield from aluminum oxide. The source will be capable of ECR plasma heating using two different frequencies simultaneously to increase the electron energy gain for the production of high charge states. To be able to deliver usable intensities of the heaviest ion beams, the design will also allow axial access for metal evaporation ovens and solid material samples using the plasma sputtering technique. The main design goal is to produce several e{mu}A of at least {sup 238}U{sup 34+} in order to accelerate the beam to coulomb-barrier energies without further stripping. First charge state distributions for {sup 16}0 and {sup 40}Ar have been measured.
Date: April 1, 1997
Creator: Schlapp, M.; Vondrasek, R.C.; Szczech, J.; Billquist, P.J.; Pardo, R.C.; Xie, Z.Q. et al.
Partner: UNT Libraries Government Documents Department

Interaction of relativistic gold and other heavy nuclei. Progress report, March 15, 1993--March 14, 1994

Description: The author has extended this work to the highest energy beams. Multiplicity distributions of shower particles were produced in high energy collisions of {sup 28}Si at 14.5A GeV, {sup 32}S at 200A GeV, {sup 16}O at 200A GeV and 60A GeV. They have studied these distributions in small pseudorapidity intervals of the forward and backward hemispheres in their perspective of Negative Binomial Distribution. Different multiplicity parameters have been computed for the two hemispheres separately and their variations with the phase space interval size have been studied.
Date: March 1, 1995
Creator: Jain, P.L.
Partner: UNT Libraries Government Documents Department

A new 14 GH{sub z} electron-cyclotron-resonance ion source (ECRIS) for the heavy ion accelerator facility ATLAS

Description: A new 14 GHz ECRIS has been designed and built over the last two years. The source design incorporates the latest results from ECR developments to produce intense beams of highly charged ions. An improved magnetic electron confinement is achieved from a large mirror ratio and strong hexapole field. The aluminum plasma chamber and extraction electrode as well as a biased disk on axis at the microwave injection side donate additional electrons to the plasma, making use of the large secondary electron yields from aluminum oxide. The source will be capable of ECR plasma heating using two different frequencies simultaneously to increase the electron energy gain. To be able to deliver usable intensities of the heaviest ion beams the design will also allow axial access for metal evaporation ovens and solid material. The main design goal is to produce several e{mu}A of at least {sup 238}U{sup 34+} in order to accelerate the beam to coulomb-barrier energies without further stripping. First charge state distributions for {sup 16}O and {sup 40}Ar have been measured.
Date: September 1, 1997
Creator: Schlapp, M.; Vondrasek, R.C.; Szczech, J.; Biliquist, P.J.; Pardo, R.C.; Xie, Z.Q. et al.
Partner: UNT Libraries Government Documents Department

R-Matrix Evaluation of 160 Neutron Cross Sections up to 6.3 MeV

Description: We have evaluated {sup 16}O neutron cross sections in the resolved resonance region with the multilevel Reich-Moore code SAMMY. Resonance parameters were determined by a consistent analysis, including both Doppler and resolution broadening effects. To properly treat the {alpha} particle exit channel, an algorithm to calculate charged particle penetrabilities and shifts was incorporated into SAMMY.
Date: August 31, 2001
Creator: Sayer, R.O.
Partner: UNT Libraries Government Documents Department

STRUCTURE OF P-SHELL HYPERNUCLEI

Description: New {gamma}-ray data for {sub {Lambda}}{sup 7}Li from KEK E419 and new ({pi}{sup +}, K{sup +}) data on {sup 12}C, {sup 13}C, and {sup 16}0 targets from KEK E336 and E369 is used to update Millener, Gal, Dover and Dalitz's 1985 analysis of the spin dependence of the effective AN interaction.
Date: February 19, 1999
Creator: MILLENER,D.J.
Partner: UNT Libraries Government Documents Department

Dynamical relativistic effects in quasielastic 1 {rho}-shell proton knockout from {sup 16}O

Description: The authors have measured the cross section for quasielastic 1 {rho}-shell proton knockout in the (sup 16)O (e, e{prime}p) reaction at {omega} = 0.439 GeV and Q{sup 2} = 0.8 (GeV/c){sup 2} for missing momentum P{sub miss} {<=} 355 MeV/c. They have extracted the response functions R{sub L+TT}, R{sub T}, R{sub LT}, and the left-right asymmetry, A{sub LT}, for the 1{rho}{sub 1/2} and the 1{rho}{sub 3/2} states. The data are well described by relativistic distorted wave impulse approximation calculations. At large P{sub miss}, the structure observed in A{sub LT} indicates the existence of dynamical relativistic effects.
Date: July 1999
Partner: UNT Libraries Government Documents Department