Differential angular distribution of prompt gamma rays from spontaneous fission of /sup 252/Cf

Journal Article · Fri Aug 01 00:00:00 EDT 1980 · Phys. Rev., C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.22.638· OSTI ID:5206645

Skarsvag, K

The differential angular distribution of prompt ..gamma.. rays from spontaneous fission of /sup 252/Cf has been measured. The total number of ..gamma.. rays emitted within 12 ns after fission with energies greater than 0.114 MeV is 9.7 +- 0.4 per fission, and the total ..gamma..-ray energy released is (7.0 +- 0.3) MeV per fission. More ..gamma.. rays were emitted from the light than from the heavy fragment group. The anisotropy A=I(0/sup 0/)/I(90/sup 0/)-1 is small and even negative at low energies, reaches a maximum of about 25% at energies of about 0.50 -- 0.65 MeV, and gets gradually smaller at higher energies. With the assumption that the angular momentum is aligned in a plane perpendicular to the direction of fission, the results can be consistently described within the statistical model in terms of pure dipole and quadrupole radiation with allowance for stretched E2 cascades from even-even fragments. It is concluded that the root mean square value of the primary angular momentum of the fragments is J/sub rms/= (6.5 +- 1.0)h-bar, the average angular momentum is decreasing 1.0h-bar per ..gamma.. ray emitted, and the value of the spin cutoff parameter during ..gamma..-ray deexcitation of the fragments is sigma=2.4/sup +0.8//sub -0.5/. The dipole and the quadrupole components are about equally strong at high ..gamma..-ray energies, the dipole component predominates at low energies, and the quadrupole component, at intermediate energies. Statistical dipole and quadrupole transitions (stretched for the last ones) account for 38% and 50% of the ..gamma.. rays, respectively, and stretched E2 transitions in cascades from even-even fragments account for the remaining 12% of the ..gamma.. rays. While components of stretched E2 cascades can be accounted for by transitions in ground-state rotational bands, it is indicated that a large part of the components can be associated with vibrational transitions in even-even fragments.

• Research Organization: Institutt for Atomenergi, Kjeller Research Establishment, 2007 Kjeller, Norway
• OSTI ID: 5206645
• Journal Information: Phys. Rev., C; (United States), Vol. 22:2
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CALIFORNIUM 252
SPONTANEOUS FISSION
ANGULAR DISTRIBUTION
CORRELATION FUNCTIONS
DIFFERENTIAL CROSS SECTIONS
E2-TRANSITIONS
FISSION FRAGMENTS
PROMPT GAMMA RADIATION
ROTATIONAL STATES
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
CALIFORNIUM ISOTOPES
CROSS SECTIONS
DECAY
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EVEN-EVEN NUCLEI
EXCITED STATES
FISSION
FUNCTIONS
GAMMA RADIATION
HEAVY NUCLEI
IONIZING RADIATIONS
ISOTOPES
MULTIPOLE TRANSITIONS
NUCLEAR FRAGMENTS
NUCLEAR REACTIONS
NUCLEI
RADIATIONS
RADIOISOTOPES
YEARS LIVING RADIOISOTOPES
652026* - Nuclear Properties & Reactions
A=220 & above
Experimental- Spontaneous & Induced Fission- (-1987)
652023 - Nuclear Properties & Reactions
A=220 & above
Experimental- Energy Levels & Transitions- (-1987)