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in subjects: "Pion Minus Reactions"

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Study of Isovector Resonances With Pion Charge Exchange

Studies with the pion charge exchange reactions (..pi../sup +-/,..pi../sup 0/) at 164 MeV using the LAMPF ..pi../sup 0/ spectrometer are yielding new results on the existence and systematic features of isovector resonances in nuclei. These experiments possess an unusually high signal/background ratio for isovector resonances of low-multipolarity. Results obtained to date are: (1) observation and angular disribution measurement of the giant dipole resonance in nuclei /sup 12/C, /sup 40/Ca, /sup … more

Date: January 1, 1982

Creator: Baer, H.W.; Bolton, R. & Bowman, J.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experiments on eta-meson production

Following a review of some highlights of eta-meson characteristics, the status of eta-meson production experiments is reviewed. The physics motivations and first results of two LAMPF experiments on (..pi..,eta) reactions are discussed. Possible future experiments are also discussed. 42 refs., 12 figs., 4 tabs.

Date: January 1, 1985

Creator: Peng, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experimental nuclear and radiochemistry. Progress report, February 1, 1979-January 31, 1980. [Dept. of Chemistry, Carnegie-Mellon Univ. , Pittsburgh, Pennsylvania, 2/1/79 to 1/31/80]

This project entails the investigation of deep nuclear spallation reactions induced by high-energy light particles on complex nuclei. Experimental studies involve activation of various medium- to heavy-mass targets bombarded by pi mesons, protons, and alpha particles. A prime objective is to deconvolve the cascade and evaporation steps in the reaction mechanism. Experimentally, then, particular emphasis has been placed on spallation products far from yield maxima. Irradiations have been perform… more

Date: January 1, 1980

Creator: Karol, P. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Eta-meson production experiments at LAMPF

Results of recent experiments on (..pi.., eta) ractions in nuclei are reported. These results include triton and eta spectra for the /sup 3/He(..pi../sup -/,+) and /sup 3/He(..pi../sup -/,eta) reactions. Also measured were forward angle cross sections and inclusive cross sections on a number of nuclei at three pion momenta for (..pi../sup +/,eta) reactions. (DWL) 3 refs., 4 figs.

Date: January 1, 1986

Creator: Peng, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mechanism of pion absorption in complex nuclei

Basic geometrical arguments are used to analyze the A dependence of the total pion absorption cross section, the effective number of nucleons sharing the pion momentum and energy, and the proton yields from ..pi../sup +/- and ..pi../sup -/-induced reactions. The results are consistent with the pions penetrating some distance through the nuclear volume and annihilating on a pair of nucleons. 3 figures.

Date: unknown

Creator: Doss, K.G.N. & Wharton, W.R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The sup 11 Li neutron halo radius from pion double charge exchange

We have analyzed the pion double charge exchange data for the direct population of the ground state of {sup 11}Li by the {sup 11}B({pi}{sup minus},{pi}{sup +}){sup 11}Li reaction and find that the measured cross section determines the rms radius of the last two neutrons in {sup 11}Li to be 5.1{sub {minus}0.8}{sup +0.6} fm. 8 refs., 2 figs.

Date: January 1, 1991

Creator: Gibbs, W.R. & Hayes, A.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Can we learn about the spin-flip giant dipole resonances with pions

Data and calculations for the /sup 40/Ca(..pi..+-,..pi../sup 0/) reactions at 164 MeV are shown which indicate that pion scattering possesses a unique signature for separately identifying the 1/sup -/ and 2/sup -/ spin-isospin components of the giant dipole resonance.

Date: January 1, 1982

Creator: Baer, H.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Nuclear structure studies with pions and heavy ions. Progress report, June 1, 1979-May 31, 1980. [Univ. of Minnesota, June 1, 1979-May 31, 1980]

The elastic and inelastic scattering of ..pi../sup +/ and ..pi../sup -/ by /sup 13/C, /sup 16/O, and /sup 17/O was studied at pion energies close to the (3,3) resonance. Data were taken at the Los Alamos Meson Physics Facility. Large asymmetries were observed, two of which are consistent with pure neutron and pure proton excitations. Transitions to strongly excited states of /sup 13/C are in strikingly good agreement with theoretical predictions of Lee and Kurath. In sharp contrast, strong disa… more

Date: March 1, 1980

Creator: Dehnhard, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The sup 11 Li neutron halo radius from pion double charge exchange

We have analzed the pion double charge exchange data for the direct population of the ground state of {sup 11}Li by the {sup 11}B({pi}{sup {minus}}, {pi}{sup +}){sup 11}Li reaction and find that the measured cross section determines the rms radius of the last two neutrons in {sup 11}Li to be 5.1{sub {minus} 0.8}{sup +0.6} fm. It is shown that the pion cross-section falls off as the sixth power of the assumed neutron halo radius, so that a radius greater than about 6 fm is ruled out. Indeed, pio… more

Date: January 1, 1991

Creator: Hayes, A.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Multiple preequilibrium decay processes

Several treatments of multiple preequilibrium decay are reviewed with emphasis on the exciton and hybrid models. We show the expected behavior of this decay mode as a function of incident nucleon energy. The algorithms used in the hybrid model treatment are reviewed, and comparisons are made between predictions of the hybrid model and a broad range of experimental results. 24 refs., 20 figs.

Date: November 1, 1987

Creator: Blann, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Isovector resonances in pion charge exchange

The (..pi../sup + -/, ..pi../sup 0/) reactions as probes of isovector resonances are discussed. Experimental observation of the isovector monopole resonance is reported. Experimental results are presented for L = 0, 1, and 2 isovector resonances and are compared to random-phase approximation calculations.

Date: January 1, 1985

Creator: Bowman, J. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Pion single charge exchange. [Angular distribution, cross sections, preliminary results, 200 MeV]

The LAMPF ..pi../sup 0/ spectrometer is described, and the first results of pion single charge exchange to discrete nuclear states are discussed. Angular distribution information was obtained in /sup 3/He, and 0/sup 0/ excitation functions for the isobaric analog state were observed in targets throughout the periodic table. 8 references.

Date: January 1, 1979

Creator: Cooper, M.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Study of elastic pion scattering from /sup 9/Be, /sup 28/Si, /sup 58/Ni, and /sup 208/Pb at 162 MeV. [Total and differential cross sections, scattering yields, scattering amplitudes]

Elastic pion scattering from /sup 9/Be, /sup 28/Si, /sup 58/Ni, and /sup 208/Pb at 162 MeV is analyzed and compared with an optical model theory which incorporates a pion--nucleon range. Excellent fits to the data are obtained in all but one case. The fitted values of the pion--nucleon range, as well as other fitted values are listed. 108 references.

Date: May 1, 1979

Creator: Devereux, M.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Structure of /sup 13/C studied by pion scattering near the (3,3) resonance

Good resolution (..pi../sup +/,..pi../sup +/') and (..pi../sup -/,..pi../sup -/') data were obtained for many states in /sup 13/C using the Energetic Pion Channel and Spectrometer at the Los Alamos Meson Physics Facility. Differential cross sections were measured for angles between 20/sup 0/ and 105/sup 0/ at an incident pion energy of 162 MeV for the elastic scattering as well as for states at excitation energies of 3.09, 3.68, 3.85, 7.55, 8.86, 9.5, 11.82, 16.05, 17.92, 21.37, and 21.6 MeV. E… more

Date: September 1, 1981

Creator: Seestrom-Morris, S.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Bilocal field theory and a model for meson spectroscopy. Part I. Trident production by high energy charged particles on nuclei. Part II. [Harmonic oscillator quark model, radiative corrections, cross sections covariant perturbation theory, interference]

Bilocal field theory for quark confinement is considered in a combination of bilocal field theory with the covariant harmonic oscillator quark model. The formalism can be viewed as a direct generalization of local Lagrangian field theory. Following the usual local theory, the variational principle is used to find the Euler - Lagrange equation for the bilocal field. For a special class of Lagrangian densities satisfying a boundary condition on the hypersurface of the internal domain which is cal… more

Date: May 1, 1979

Creator: Mita, K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Dependence of the excitation energy, width, and cross section of the isovector monopole resonance

We have used the (..pi../sup -/,..pi../sup 0/) charge-exchange reaction at 165-MeV kinetic energy to study the T + 1 component of the isovector monopole resonance (IVM). The nuclei /sup 40/Ca, /sup 61/Ni, /sup 90/Zr, /sup 120/Sn, /sup 140/Ce, and /sup 208/Pb were used as targets. We also observed the T + 1 component of the giant dipole resonance (GDR) in the lighter targets. The (..pi../sup +/,..pi../sup 0/) reaction also yielded positive results for the T - 1 component of the IVM and GDR in /s… more

Date: January 1, 1983

Creator: Bowman, J. D.; Baer, H. W.; Cooper, M. D.; King, N. S. P.; Matis, H. S.; Piasetzky, E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High resolution studies of pion-nucleus reaction mechanism

Pion inelastic scattering is generally well described as a first order process using the DWIA. This is especially true for a large body of inelastic scattering data to low-lying collective states which is well-described by form factors obtained in (e,e') and the DWIA. Some data for which this model does not work are presented. Higher order reaction mechanisms have been invoked to explain some of these data. However, no model of these second order processes gives a satisfactory explanation of th… more

Date: January 1, 1983

Creator: Morris, C.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Prospects for studying the (. pi. sup minus ,K sup 0 ) reaction at PILAC

The ({pi}{sup {minus}},K{degree}) reaction, which complements the ({pi}{sup +},K{sup +}) reaction, offers another means to study {Lambda}-hypernulei at PILAC. The physics motivation for measuring the ({pi}{sup {minus}},K{degree}) reaction is discussed. The feasibility or detecting K{degree} at PILAC using the LAMPF Neutral Meson Spectrometer and a simple dipole spectrometer is studied with Monte-Carlo simulations. We conclude that the ({pi}{sup {minus}},K{degree}) reaction can be well pursued a… more

Date: January 1, 1990

Creator: Peng, Jen-Chieh.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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SU(3) symmetries in exotic neutron-rich nuclei

We examine the structure of the exotic neutron-rich nucleus {sup 11}Li with an emphasis on understanding the origin of the soft E1 resonance and the neuron halo. The similarities and differences between shell model and di-neutron cluster model descriptions of the system are displayed using the Hecht expansion techniques. We find that the ground state {sup 11}Li as described in large shell model calculations is well approximated by the di-neutron cluster state. In contrast to the ground state, t… more

Date: January 1, 1991

Creator: Hayes, A.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Pion-induced meson production in nuclei: The (. pi. ,eta) and the (. pi. /sup +/,K/sup +/) reactions

The subject of meson productions in nuclei, a new direction in pion-nucleus physics, is discussed. Recent experimental results at LAMPF and AGS on the (..pi..,eta) and (..pi../sup +/,K/sup +/) reactions in nuclei are presented. 37 refs., 14 figs., 4 tabs.

Date: June 1, 1987

Creator: Peng, J.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Annual progress report

Elementary particle physics research at the University of Illinois and at high energy particle accelerator laboratories operated by DOE is described. Major accomplishments in 1980 include: determination of the diffractive cross section for production of charmed D mesons in ..pi../sup -/p collisions at 215 GeV/c to be 20 ..mu..b; data acquisition for ..pi../sup -/ beryllium at 215 GeV/c; construction and testing of prototype muon drift tubes for the p anti p detector facility; Monte Carlo studie… more

Date: May 1, 1981

Creator: Wattenberg, A. & Simmons, R. O.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Nuclear Moments and Nuclear Structure. Annual Progress Report, August 1, 1981-August 31, 1982

This report is a review of the activities of the period from August 1, 1981 through August 31, 1982. The final analysis of pi-zero production in heavy ion collisions representing experiments at the Bevalac with a system previously described is completed. The main results involve cross sections for central collisions resulting in the production of pi-zeros, charged pions, and proton multiplicities, and some results of correlations and low energy gamma radiation. Results from the alpha-alpha expe… more

Date: January 1, 1982

Creator: Madansky, L. & Lee, Y. K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Isovector resonances in pion single-charge-exchange reactions

An experimental study of L = 0, 1, and 2 isovector resonances in pion charge-exchange reactions is reported. In these experiments well-understood, spherical, even-even nuclei were studied at 120, 165, and 230 MeV. The emphasis of the 165 MeV study was on L = 0, 1, and 2 isovector resonances as a function of the atomic mass of the target. The targets were Ca-40, Ni-60, Zr-90, Sn-120, Ce-140, and Pb-208. The 120 and 230 MeV studies were aimed at measuring the properties of the isovector resonance… more

Date: October 1, 1986

Creator: Bowman, J. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Production of muon pairs with masses greater than 4 GeV/c/sup 2/ in anti p N and. pi. /sup -/N interactions at 125 GeV/c

We have measured the high mass (M > 4 GeV/c/sup 2/) dimuons produced in anti-proton-nucleon and pi minus-nucleon interactions. Preliminary differential cross sections are presented as a function of pair mass, x/suf F/, p/sub T/, and ..sqrt.. tau. Comparisons of these cross sections with the predictions of the Drell-Yan model are discussed and preliminary values for the K factor for the anti p and ..pi../sup -/ induced reactions are reported.

Date: July 1, 1982

Creator: Anassontzis, E.; Katsanevas, S. & Kostarakis, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department