Giant dipole resonance decay from fusion-fission and quasifission of hot thorium nuclei

Journal Article · Sat Aug 01 04:00:00 EDT 1992 · Physical Review, C (Nuclear Physics); (United States)

DOI:https://doi.org/10.1103/PhysRevC.46.627· OSTI ID:7035036

Dioszegi, I; Hofman, D J; Montoya, C P; Schadmand, S; Paul, P ^[1]

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1. Department of Physics, State University of New York at Stony Brook, Stony Brook, New York 11794 (United States)

Giant dipole resonance (GDR) {gamma} rays were measured in kinematic coincidence with fission fragments in the reactions {sup 16}O+{sup 208}Pb at 140 MeV, and {sup 32}S+{sup nat}W at 185, 215, and 230 MeV bombarding energy, leading to {sup {similar to}216,224}Th at a temperature of {ital T}{approx}1.8 to 2.1 MeV. The experiment determined the {gamma}-ray spectrum and the {gamma}-ray-fission fragment angular correlation as a function of fragment mass, kinetic energy, and total kinetic energy release. The coincidence {gamma}-ray spectra are fitted successfully and consistently in terms of the statistical decay of the hot compound system and of the fission fragments, when a large nuclear dissipation ({gamma}=10) and, for the {sup 32}S+{sup nat}W reaction, the GDR {gamma} emission during the quasifission process is included. The {gamma}-ray-fission fragment angular correlation indicates a deformed compound system in {sup 224}Th of either strongly prolate ({beta}=0.3) or noncollective oblate ({beta}={minus}0.1) shape. This is consistent with, but does not prove, a transition to a liquid drop shape having occurred at {ital T}{approx}1.8 MeV. The quasifission process is successfully included using regular extra-push and extra-extra-push energies and a quasifission lifetime {tau}{sub QF}=(20--40){times}10{sup {minus}21} sec. This is about ten times shorter than the compound nucleus fission lifetime in {sup 224}Th at this temperature.

• OSTI ID: 7035036
• Journal Information: Physical Review, C (Nuclear Physics); (United States), Journal Name: Physical Review, C (Nuclear Physics); (United States) Vol. 46:2; ISSN 0556-2813; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

663450* -- Heavy-Ion-Induced Reactions & Scattering-- (1992-)
663470 -- Fission-- (1992-)
663580 -- Nuclear Mass Ranges-- A=190-219-- (1992-)
663590 -- Nuclear Mass Ranges-- A=220 & Above-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
CHARGED-PARTICLE REACTIONS
COINCIDENCE METHODS
COMPOUND NUCLEI
COUNTING TECHNIQUES
E1-TRANSITIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EVEN-EVEN NUCLEI
FISSION
FISSION FRAGMENTS
GAMMA RADIATION
GIANT RESONANCE
HEAVY ION FUSION REACTIONS
HEAVY ION REACTIONS
HEAVY NUCLEI
IONIZING RADIATIONS
ISOTOPES
LEAD 208 TARGET
LIFETIME
METALS
MEV RANGE
MEV RANGE 100-1000
MILLISEC LIVING RADIOISOTOPES
MULTIPOLE TRANSITIONS
NUCLEAR FRAGMENTS
NUCLEAR REACTIONS
NUCLEI
OXYGEN 16 REACTIONS
QUASI-FISSION
RADIATIONS
RADIOISOTOPES
RESONANCE
SECONDS LIVING RADIOISOTOPES
SULFUR 32 REACTIONS
TARGETS
THORIUM 216
THORIUM 224
THORIUM ISOTOPES
TRANSITION ELEMENTS
TUNGSTEN