Spontaneous fission properties of 2. 9-s sup 256 No

Journal Article · Thu Feb 01 00:00:00 EST 1990 · Physical Review, C (Nuclear Physics); (USA)

DOI:https://doi.org/10.1103/PhysRevC.41.631· OSTI ID:7102673

Hoffman, D C; Lee, D M; Gregorich, K E; Nurmia, M J; Chadwick, R B; Chen, K B; Czerwinski, K R; Gannett, C M; Hall, H L; Henderson, R A; Kadkhodayan, B; Kreek, S A; Leyba, J D ^[1]

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1. Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (US) Chemistry Department, University of California, Berkeley, Berkeley, California 94720

We have measured the mass and kinetic-energy distributions of fragments from the spontaneous fission of {sup 256}No produced via the {sup 248}Cm({sup 12}C,4{ital n}) reaction. The production cross section using 71-MeV {sup 12}C projectiles was found to be 250 nb. The total kinetic energy for spontaneous fission of {sup 256}No is 196{plus minus}3 MeV. The mass distribution is very broad (full width at half maximum of {similar to}50 mass units) with no appreciable decrease in yield for symmetric mass division. {sup 256}No seems to be the transition nucleus between the asymmetric mass division observed for spontaneous fission of the lighter No isotopes and the symmetric mass division observed for the heavier No isotopes. Its properties are similar to those of {sup 257}Fm, the isotope at which this transition occurs in the Fm isotopes, but the {sup 256}No mass distribution is broader than that for {sup 257}Fm, and its average total kinetic energy for symmetric mass division is about 15 MeV lower. We determined the half-life of {sup 256}No to be 2.91{plus minus}0.05 s by measuring its {alpha} decay. We measured a spontaneous fission to {alpha} ratio of 0.0053{sub {minus}0.0003}{sup +0.0006}, which gives a partial half-life for spontaneous fission of 550{sub {minus}70}{sup +40} s. An energy of 8.448{plus minus}0.006 MeV was measured for the {alpha}-particle decay to the ground state of {sup 252}Fm, allowing us to calculate the mass excess for {sup 256}No as 87820{plus minus}8 keV. The energy of the 2{sup +} rotational level in the {sup 252}Fm daughter is 47{plus minus}5 keV, and the intensity of the 8.402-MeV {alpha} group populating this level is (13{plus minus}2)%.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7102673
• Journal Information: Physical Review, C (Nuclear Physics); (USA), Vol. 41:2; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
NOBELIUM 256
SPONTANEOUS FISSION
ALPHA DECAY
CARBON 12 REACTIONS
COMPOUND-NUCLEUS REACTIONS
CURIUM 248 TARGET
EXPERIMENTAL DATA
FERMIUM 252
FISSION FRAGMENTS
FISSION RATIO
HALF-LIFE
KINETIC ENERGY
LBL 88-INCH CYCLOTRON
MASS DISTRIBUTION
ROTATIONAL STATES
ACCELERATORS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
CHARGED-PARTICLE REACTIONS
CYCLIC ACCELERATORS
CYCLOTRONS
DATA
DECAY
DISTRIBUTION
ENERGY
ENERGY LEVELS
EVEN-EVEN NUCLEI
EXCITED STATES
FERMIUM ISOTOPES
FISSION
HEAVY ION REACTIONS
HEAVY NUCLEI
HOURS LIVING RADIOISOTOPES
INFORMATION
ISOCHRONOUS CYCLOTRONS
ISOTOPES
NOBELIUM ISOTOPES
NUCLEAR DECAY
NUCLEAR FRAGMENTS
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
RADIOISOTOPES
SPATIAL DISTRIBUTION
TARGETS
UCLRL CYCLOTRONS
652020* - Nuclear Properties & Reactions
A=220 & above
Experimental