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Title: Scission gamma rays

Gamma rays probably emitted by the fissioning nucleus {sup 236}U* at the instant of the break of the neck or within the time of about 10{sup -21} s after or before this were discovered in the experiment devoted to searches for the effect of rotation of the fissioning nucleus in the process {sup 235}U(n,{gamma}f) and performed in a polarized beam of cold neutrons from the MEPHISTO Guideline at the FRM II Munich reactor. Detailed investigations revealed that the angular distribution of these gamma rays is compatible with the assumption of the dipole character of the radiation and that their energy spectrum differs substantially from the spectrum of prompt fission gamma rays. In the measured interval 250-600 keV, this spectrum can be described by an exponential function at the exponent value of {alpha} = -5 x 10{sup -3} keV{sup -1}. The mechanism of radiation of such gamma rays is not known at the present time. Theoretical models based on the phenomenon of the electric giant dipole resonance in a strongly deformed fissioning nucleus or in a fission fragment predict harder radiation whose spectrum differs substantially from the spectrum measured in the present study.
Authors:
 [1] ;  [2] ; ; ; ; ;  [1]
  1. Institute of Theoretical and Experimental Physics (Russian Federation)
  2. Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) (Germany)
Publication Date:
OSTI Identifier:
21449001
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Atomic Nuclei; Journal Volume: 72; Journal Issue: 11; Other Information: DOI: 10.1134/S1063778809110027; Copyright (c) 2009 Pleiades Publishing, Ltd.
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ANGULAR DISTRIBUTION; COLD NEUTRONS; COLOR MODEL; DIPOLES; ENERGY SPECTRA; FISSION; FISSION FRAGMENTS; FRM-II REACTOR; GAMMA RADIATION; POLARIZED BEAMS; URANIUM 235; URANIUM 236 ACTINIDE NUCLEI; ALPHA DECAY RADIOISOTOPES; BARYONS; BEAMS; COMPOSITE MODELS; DISTRIBUTION; ELECTROMAGNETIC RADIATION; ELEMENTARY PARTICLES; ENRICHED URANIUM REACTORS; EVEN-EVEN NUCLEI; EVEN-ODD NUCLEI; FERMIONS; HADRONS; HEAVY NUCLEI; HEAVY WATER MODERATED REACTORS; INTERNAL CONVERSION RADIOISOTOPES; IONIZING RADIATIONS; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; MATHEMATICAL MODELS; MINUTES LIVING RADIOISOTOPES; MULTIPOLES; NEUTRONS; NUCLEAR FRAGMENTS; NUCLEAR REACTIONS; NUCLEI; NUCLEONS; PARTICLE MODELS; POOL TYPE REACTORS; QUARK MODEL; RADIATIONS; RADIOISOTOPES; REACTORS; RESEARCH AND TEST REACTORS; RESEARCH REACTORS; SPECTRA; SPONTANEOUS FISSION RADIOISOTOPES; THERMAL REACTORS; URANIUM ISOTOPES; WATER COOLED REACTORS; WATER MODERATED REACTORS; YEARS LIVING RADIOISOTOPES