A shelf in the "subthreshold" photofission cross section

Journal Article · Mon Sep 01 04:00:00 EDT 1975 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PhysRevC.12.856· OSTI ID:4154862

Bowman, Charles D.

The influence of a double-humped fission barrier on the photofission cross section far below the top of the barrier is considered. In the region about 2 MeV below the top of the outer barrier and at a cross section in the region of 10^-9-10^-6 b the photofission is expected to become almost entirely isomeric or delayed fission. When this occurs a ''shelf'' should appear in the photofission cross section where the cross section changes with energy far more slowly than at higher γ-ray energy. The cross section on the shelf can therefore be orders of magnitude higher than otherwise expected. While the angular distribution near the top of the barrier is expected to have a well- defined and nonisotropic angular dependence, the angular distribution on the shelf is expected to be isotropic. The cross sections, although small, appear to be measurable with bremsstrahlung beams in the 3 to 5 MeV range using a several hundred μA electron beam. Successful experiments of this type should provide information on the shape of the inner and outer barriers at much lower excitation energies than possible by other techniques.

• Research Organization: National Bureau of Standards, Washington, D. C. 20234
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-004506
• OSTI ID: 4154862
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 3 Vol. 12; ISSN 0556-2813; ISSN PRVCAN
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

*PHOTOFISSION-- FISSION BARRIER
643506*
ANGULAR DISTRIBUTION
BREMSSTRAHLUNG
CROSS SECTIONS
ISOMERIC NUCLEI
MEV RANGE 01-10
N69260* --Physics (Nuclear)--Nuclear Theory--Spontaneous & Induced Fission
NUCLEAR DEFORMATION
POTENTIAL ENERGY