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Title: Subthreshold pion production in the reaction sup 139 La + sup 139 La yields. pi. sup + + X

Abstract

Charged pion production has been measured in the reaction of {sup 139}La + {sup 139}La{yields} {pi}{sup {plus minus}} + X at three bean energies (246, 183 and 138 MeV/nucleon) below the nucleon-nucleon threshold. Associated multiplicity for charged participants was obtained using a 110-element scintillator multiplicity array. Data were taken over the angular range of 21{degree}-67{degree} in the laboratory (equivalent to 30{degree}-90{degree} in the center of mass). Dependence of the spectra upon pion charge, energy and angle, beam energy, system mass and associated multiplicity was investigated. Based on the isotropic angular distributions and the associated multiplicities for pion production, it appears that subthreshold pions in the range of the experiment are produced predominantly from a source at rest in the center of mass and involving a large number of nucleons. The general character of the subthreshold pion spectra is comparable to previous results above threshold. However, the scaling of the subthreshold pion yield with system mass deviates from the dependence observed in light systems, to an extent which cannot be explained by a simple nucleon-nucleon model. Charge dependent structure in the pion spectra was also found, which was analyzed in the framework of both Coulomb distortion and clustering models. It wasmore » concluded that while evidence of collective effects in subthreshold pion production was not clear, it would be very worthwhile to conduct a systematic investigation of pion production for all charge states and over a range of angles, system masses and beam energies, below threshold.« less

Authors:
Publication Date:
Research Org.:
California Univ., Davis, CA (USA)
OSTI Identifier:
5467216
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; LANTHANUM 139 REACTIONS; PIONIZATION; LANTHANUM 139 TARGET; ANGULAR DISTRIBUTION; CLUSTER EMISSION MODEL; MESONS; MEV RANGE 100-1000; MULTIPLICITY; PIONS MINUS; PIONS PLUS; THRESHOLD ENERGY; BOSONS; CHARGED-PARTICLE REACTIONS; DISTRIBUTION; ELEMENTARY PARTICLES; ENERGY; ENERGY RANGE; HADRONS; HEAVY ION REACTIONS; MATHEMATICAL MODELS; MEV RANGE; MULTIPERIPHERAL MODEL; MULTIPLE PRODUCTION; NUCLEAR REACTIONS; PARTICLE MODELS; PARTICLE PRODUCTION; PERIPHERAL MODELS; PIONS; PSEUDOSCALAR MESONS; TARGETS; 651720* - Nuclear Properties & Reactions, A=90-149, Experimental

Citation Formats

Miller, J. Subthreshold pion production in the reaction sup 139 La + sup 139 La yields. pi. sup + + X. United States: N. p., 1987. Web.
Miller, J. Subthreshold pion production in the reaction sup 139 La + sup 139 La yields. pi. sup + + X. United States.
Miller, J. 1987. "Subthreshold pion production in the reaction sup 139 La + sup 139 La yields. pi. sup + + X". United States.
@article{osti_5467216,
title = {Subthreshold pion production in the reaction sup 139 La + sup 139 La yields. pi. sup + + X},
author = {Miller, J},
abstractNote = {Charged pion production has been measured in the reaction of {sup 139}La + {sup 139}La{yields} {pi}{sup {plus minus}} + X at three bean energies (246, 183 and 138 MeV/nucleon) below the nucleon-nucleon threshold. Associated multiplicity for charged participants was obtained using a 110-element scintillator multiplicity array. Data were taken over the angular range of 21{degree}-67{degree} in the laboratory (equivalent to 30{degree}-90{degree} in the center of mass). Dependence of the spectra upon pion charge, energy and angle, beam energy, system mass and associated multiplicity was investigated. Based on the isotropic angular distributions and the associated multiplicities for pion production, it appears that subthreshold pions in the range of the experiment are produced predominantly from a source at rest in the center of mass and involving a large number of nucleons. The general character of the subthreshold pion spectra is comparable to previous results above threshold. However, the scaling of the subthreshold pion yield with system mass deviates from the dependence observed in light systems, to an extent which cannot be explained by a simple nucleon-nucleon model. Charge dependent structure in the pion spectra was also found, which was analyzed in the framework of both Coulomb distortion and clustering models. It was concluded that while evidence of collective effects in subthreshold pion production was not clear, it would be very worthwhile to conduct a systematic investigation of pion production for all charge states and over a range of angles, system masses and beam energies, below threshold.},
doi = {},
url = {https://www.osti.gov/biblio/5467216}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jan 01 00:00:00 EST 1987},
month = {Thu Jan 01 00:00:00 EST 1987}
}

Thesis/Dissertation:
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