PROTON STRENGTH FUNCTIONS FROM (p,n) CROSS SECTIONS

Journal Article · Sat Feb 15 04:00:00 EST 1958 · Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D

DOI:https://doi.org/10.1103/PhysRev.109.1243· OSTI ID:4334100

Johnson, C H; Galonsky, A; Ulrich, J P

To an accuracy of plus or minus 10%, (p,n) total cross sections averaged over resonances have been measured from threshold to about 500 kev above threshold for 12 nuclei from Cl/sup 37/ to Nb/sup 93/. For each nucleus the excitation function of the average cross section is a monotonically increasing function of proton energy. At 500 kev above threshold the cross sections vary from 40 mb for Cl/sup 37/ to 5 x 10/sup -4/ mb for Nb/sup 93/. One new threshold, that for Se/sup 77/(p,n)Br/sup 77/, was found to be 2.175 plus or minus 0.004 Mev. In the course of calibrating the neutron detector with an Sb- Be source, a new determination was made of the Sb/sup 124/ half-life: 59.9 plus or minus 0.5 days. A blacknucleus square-well model was used to compute the cross sections for formation of the compound system. The Coulomb penetrabilities that appear in this calculation qualitatively account for the very large range of cross sections observed. In a more detailed comparison compoundnucleus formation was assumed, and the Hauser-Feshbach formalism was used to include the effects of proton and, especially, -ray emission from the compound nucleus. In general, there is agreement with the shapes of the excitation functions but not always with the magnitudes. The ratio of observed to black-nucleus cross-section peaks up by about a factor of 2 between Cu/sup 65/ and Se/sup 82/. The maximum in the peak is between masses 70 and 75. This peak may be correlated (by a complex- potential model) with a peak in the strength function for s-wave protons and, to a lesser extent, with a peak in the strength function for dwave protons. Proton strength functions were calculated for a complex square-well of radius R = 1.45 A/ sup 1/3/ x 10/sup -13/ cm with the approximation of a Coulomb potential constant inside the well and equal to (4/3)(Ze/sup 2//R). In order to fit the observed position of the peak, A -- 70 to 75, the depth of the specifically nuclear part of the well was required to be 46 Mev, 4 Mev deeper than the neutron well of Feshbach, Porter, and Weisskopf. (auth)

• Research Organization: Oak Ridge National Lab., Tenn.
• NSA Number: NSA-12-006883
• OSTI ID: 4334100
• 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: 109; ISSN PHRVA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ANTIMONY
ANTIMONY 124
BARRIERS
BERYLLIUM
BROMINE 77
CHLORINE 37
COMPOUND NUCLEI
COPPER 65
CROSS SECTIONS
D-WAVE
ELECTRIC FIELDS
ELEMENTARY PARTICLES
EMISSION
ENERGY RANGE
EXCITATION
GAMMA RADIATION
HALF-LIFE
MASS
NEUTRON SOURCES
NEUTRONS
NIOBIUM 93
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
PHYSICS
PROTON BEAMS
PROTONS
QUANTUM MECHANICS
RESONANCE
S-WAVE
SCATTERING
SELENIUM 77
SELENIUM 82
STANDARDS