Statistical equilibrium in the sup 40 Ar+ sup 12 C system at E / A =8 MeV

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Physical Review, C (Nuclear Physics); (USA)

DOI:https://doi.org/10.1103/PhysRevC.41.1562· OSTI ID:6901373

Lee, J H; Benenson, W ^[1]; Morrissey, D J ^[2]

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1. National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI (USA) Department of Physics Astronomy, Michigan State University, East Lansing, Michigan 48824 (USA)
2. National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI (USA) Department of Chemistry, Michigan State University, East Lansing, Michigan 48824 (USA)

The reaction of {sup 40}Ar with {sup 12}C has been studied at a bombarding energy of {ital E}/{ital A}=8 MeV. Fragments ranging from lithium to titanium isotopes were detected in charged-particle detectors placed at a small forward angle ({theta}=11{degree}). The coincident gamma rays were observed also and used to determine the populations of various bound excited states. The products could be generally described as either complex fragments or evaporation residues. An analysis of fragment velocities and a limited number of charged-particle coincidence events suggests that the complex fragments are emitted in a binary-decay process from the compound nucleus. The extent of statistical equilibrium of the compound nucleus was studied by analyzing the population distributions of both the complex fragments and the evaporation residues. The deduced nuclear temperatures of the complex fragments were found to be in general agreement with that expected for the compound nucleus. The observed (relative) populations of states in a typical evaporation residue were compared with predictions of a statistical evaporation code. The good agreement achieved suggests that heavy fragments with masses close to the total mass in the reaction are produced from the compound nucleus by the statistical emission of light particles, such as nucleons and alpha particles. The populations of states in nuclei with {ital A}{le}35, somewhat beyond the mass range of statistical evaporation, are consistent with thermal excitation, and these nuclei must be the reaction partners of the light complex fragments. Thus, all of the detected fragments are consistent with decay of an equilibrated compound nucleus by either sequential light-particle emission or binary decay into large complex fragments.

• OSTI ID: 6901373
• Journal Information: Physical Review, C (Nuclear Physics); (USA), Journal Name: Physical Review, C (Nuclear Physics); (USA) Vol. 41:4; ISSN 0556-2813; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

651520* -- Nuclear Properties & Reactions
A=39-58
Experimental
653003 -- Nuclear Theory-- Nuclear Reactions & Scattering
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALKALI METALS
ALPHA PARTICLES
ANGULAR DISTRIBUTION
ARGON 40 TARGET
BARYONS
BOUND STATE
C CODES
CARBON 12 REACTIONS
CHARGED PARTICLES
CHARGED-PARTICLE REACTIONS
COINCIDENCE SPECTROMETRY
COMPOUND-NUCLEUS REACTIONS
COMPUTER CODES
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ELEMENTS
ENERGY RANGE
EVAPORATION MODEL
FERMIONS
GAMMA RADIATION
HADRONS
HEAVY ION REACTIONS
IONIZING RADIATIONS
ISOTOPES
LITHIUM
MATHEMATICAL MODELS
METALS
MEV RANGE
MEV RANGE 10-100
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEAR TEMPERATURE
NUCLEONS
RADIATIONS
STATISTICAL MODELS
TARGETS
TITANIUM ISOTOPES