Spontaneous fission of /sup 259/Md

Conference · Fri May 04 00:00:00 EDT 1979

OSTI ID:6282693

Hulet, E K; Wild, J F; Lougheed, R W; Baisden, P A; Landrum, J H; Dougan, R J; Mustafa, M; Ghiorso, A; Nitschke, J M

The mass and kinetic energy distributions of fission fragments from the spontaneous fission of th newly discovered nuclide /sup 259/Md were obtained. /sup 259/Md was identified as the E. C. daughter of /sup 259/No, and was found to decay entirely (> 95%) by spontaneous fission with a 95-min half-life. From the kinetic energies measured for 397 pairs of coincident fragments, a mass distribution was derived that is symmetric with sigma = 13 amu. /sup 259/Md, together with /sup 258/Fm and /sup 259/Fm, form a select group of three nuclides whose mass division in spontaneous fission is highly symmetric. Unlike the total-kinetic-energy (TKE) distributions of /sup 258/Fm and /sup 259/Fm, which peak at approx. = to 240 MeV, this distribution for /sup 259/Md is broad and is 50 MeV lower in energy. Analysis of the mass and energy distributions shows that events near mass symmetry also exhibit a broad TKE distribution, with one-third of the symmetric events having TKEs less than 200 MeV. The associated of low TKEs with symmetric mass division in the fission of very heavy actinides is anomalous and inconsistent with theories based upon the emergence of fragment shells near the scission point. Either three-body fragmentation or peculiar fragment shapes are assumed as the cause for the large consumption of Coulomb energy observed for a significant fraction of symmetric fissions in /sup 259/Md. 6 figures.

• Research Organization: California Univ., Livermore (USA). Lawrence Livermore Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6282693
• Report Number(s): UCRL-81888; CONF-790507-6; TRN: 79-014214
• Resource Relation: Conference: IAEA symposium on physics and chemistry of fission, Julich, F.R. Germany, 14 May 1979
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
FISSION FRAGMENTS
KINETIC ENERGY
MASS
MENDELEVIUM 259
SPONTANEOUS FISSION
EXPERIMENTAL DATA
GRAPHS
HALF-LIFE
NUCLEAR REACTION KINETICS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
DATA
DATA FORMS
DECAY
ENERGY
FISSION
HEAVY NUCLEI
INFORMATION
KINETICS
MENDELEVIUM ISOTOPES
NUCLEAR FRAGMENTS
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
REACTION KINETICS
652026* - Nuclear Properties & Reactions
A=220 & above
Experimental- Spontaneous & Induced Fission- (-1987)