Limiting excitation energy in fusion-evaporation reactions?

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Physical Review, C

DOI:https://doi.org/10.1103/PhysRevC.55.1900· OSTI ID:541991

Lassen, L ^[1]; von Neumann-Cosel, P; Oberstedt, A; Schrieder, G ^[2]

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1. Physikalisches Institut, Universitaet Heidelberg, D-69120 Heidelberg (Germany)
2. Institut fuer Kernphysik, Technische Hochschule Darmstadt, D-64289 Darmstadt (Germany)

The systematics of fusion-evaporation reactions in the mass-symmetric system {sup 40}Ar+{sup 40}Ca are studied for incident energies of 5{endash}30 MeV/nucleon. The measurement of the resulting evaporation residues in coincidence with emitted neutrons permits a clear identification of central collisions and a separation of equilibrium and preequilibrium contributions. The total neutron multiplicities and the total average mass loss of the system both show a tendency of soft saturation. Above about 20 MeV/nucleon the increase of the energy removal is entirely due to preequilibrium emission of light particles. The total excitation energy of the evaporation residues approaches a maximum value, but the excitation energy per nucleon rises linearly without any sign of saturation. At even higher projectile energies the production of evaporation residues is dramatically reduced and they become indistinguishable from spectatorlike fragments resulting from less central collisions. Thus, the long-standing question of a limiting excitation energy in hot nuclei can probably not be solved by experimental studies of fusion-evaporation reactions. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 541991
• Journal Information: Physical Review, C, Journal Name: Physical Review, C Journal Issue: 4 Vol. 55; ISSN PRVCAN; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ARGON 40 REACTIONS
CALCIUM 40 TARGET
EQUILIBRIUM
EVAPORATION
EVAPORATION MODEL
EXCITATION
HEAVY ION FUSION REACTIONS
HOT NUCLEI
MASS
MULTIPLICITY
NEUTRONS
NUCLEAR FRAGMENTS
NUCLEAR MATTER