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(p,pn) REACTIONS AT PROTON ENERGIES FROM 0.3 TO 3.0 Bev

Journal Article · · Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D
;
Cross sections for (p,pn) reactlons on N/sup 14/,F/sup 19/, Fe/sup 54/, sup 100/, and Ta/sup 181/ were measured at proton energies of 0.4 and 3.0 Bev. For F/sup 19/, Cu/sup 65/ Mo/sup 100/ and Ta/sup 181/ cross-section measurements at several other energies between 0.3 and 3.0 Bev are reported also. Wlthin 30%, all these (p,pn) cross sections appear to be energy-independent in this range. At a given energy the cross sections show greater variations from nucleus to nucleus than can be explained on a purely statistical picture of knock- on processes. Among the lightest nuclei (C/sup 12/, N/sup 14/, O/sup 16/, Fe/sup 19/), these variations can be correlated with the energy of the lowest lying level of the product nucleus which is stable wlth respect to particle emission. Among heavier nuclei this correlation disappears, and it is suggested that shell structure effects may be responsible for the fact that the (p,pn) cross sections of Cu/sup 63/, Cu/sup 65/, and Zn/sup 64/ are about 45% hlgher than those of Fe/ sup 54/ and Ni/sup 58/. Apart from these individual variations which a statistical theory could not be expected to reproduce. it is found that the recent Monte Carlo calculations of intranuclear cascades by Metropolis et al. do not even predict the right magnitude and energy dependence for the cross sections. The calculated cross sections are too small by factors of 2 to 3 at 0.4 Bev and show a decrease with increasing energy. Possible reasons for these discrepancies are sought ln details of the nuclear model used in the calculatlons. Various mechanisms which may contribute to (p.pn) reactions are discussed. It is concluded that deuteron emission cannot contribute significantly at the energies considered. Processes involving evaporation of one of the nucleons are likely to decrease in importance with increasing energy, whereas the contribution of meson reactions, such as (p,pn pi /sup 0/),. (p.2p pi ), etc., probably increases with energy. The observed energy independence of the cross sections may result from accidental cancellation of such opposing trends. (auth)
Research Organization:
Princeton Univ., N.J.; Brookhaven National Lab., Upton, N.Y.
NSA Number:
NSA-13-008150
OSTI ID:
4297228
Journal Information:
Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 112; ISSN PHRVA
Country of Publication:
Country unknown/Code not available
Language:
English

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Related Subjects

CARBON 12
COPPER 63
COPPER 65
CROSS SECTIONS
DEUTERONS
ENERGY
ENERGY LEVELS
ENERGY RANGE
ERRORS
EVAPORATION
FLUORINE 19
IRON 54
MEASURED VALUES
MESONS
MOLYBDENUM 100
NEUTRONS
NICKEL 58
NITROGEN 14
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEAR STRUCTURE
NUCLEAR THEORY
NUMERICALS
OXYGEN 16
PHYSICS AND MATHEMATICS
PIONS
PROTON BEAMS
PROTONS
SHELL MODELS
STATISTICS
TANTALUM 181
ZINC 64