Violent collisions and multifragment final states in the [sup 40]Ca+[sup 40]Ca reaction at 35 MeV/nucleon

Journal Article · Sat Oct 01 00:00:00 EDT 1994 · Physical Review, C (Nuclear Physics); (United States)

DOI:https://doi.org/10.1103/PhysRevC.50.2017· OSTI ID:7169318

Hagel, K; Gonin, M; Wada, R; Natowitz, J B; Haddad, F; Lou, Y; Gui, M; Utley, D; Xiao, B; Li, J ^[1]; Nebbia, G; Fabris, D; Prete, G; Ruiz, J ^[2]; Drain, D; Chambon, B; Cheynis, B; Guinet, D; Hu, X C; Demeyer, A ; Pastor, C ^[3]; Giorni, A; Lleres, A; Stassi, P; Viano, J B ^[4]; Gonthier, P ^[5]

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1. Cyclotron Institute, Texas A M University, College Station, Texas 77843 (United States)
2. Istituto Nazionale di Fisica Nucleare-Legnaro, I-35020, Legnaro (Italy)
3. Institut de Physique Nucleaire-Lyon, 69622, Villeurbanne Cedex (France)
4. Institut des Sciences Nucleaire-Grenoble, 38026 Grenoble-Cedex (France)
5. Hope College, Holland, Michigan 49423 (United States)

The 4[pi] multidetector AMPHORA has been used to measure yield distributions and energy spectra for products of the collisions in the reactions of [sup 40]Ca with [sup 40]Ca at 35 MeV/nucleon. Events of high multiplicity ([ge]10) for which [ge]85% of the total entrance channel atomic number is detected have been isolated and found to result from the most violent collisions which lead to excitation energies near 6 MeV/nucleon. A large fraction of these collisions lead to multifragment final states. A detailed comparison of the experimental data with results of various models indicates that statistical models which allow for expansion of the system or treat the multifragmentation process as a simultaneous disassembly are more successful than normal sequential binary models at reproducing the yield data and the event complexity inherent in the multifragment events. Quantum molecular dynamic (QMD) calculations are found to provide generally good agreement with the data but overestimate the proton and neutron emission. The agreement is significantly improved if an appropriate afterburner is used to deexcite the separated primary QMD fragments. The sensitivity of such hybrid calculations to the assumed matching time between the dynamical calculation and the afterburner has been explored. The experimentally filtered QMD calculations which provide good agreement with the experimental observables suggest that the most complex events observed in this work come not from the most central collisions, which decay more by light particle emission, but from a region of impact parameter [ital b]/[ital b][sub max]=0.5. This suggests that angular momentum effects play an important role in the multifragment decay modes. A comparison of the present results with those for projectile fragmentation in intermediate impact parameter collisions of 600 MeV/nucleon [sup 197]Au with Cu indicates that a similar multifragmenting system is produced in the two very different reaction systems.

• DOE Contract Number: FG05-86ER40256
• OSTI ID: 7169318
• Journal Information: Physical Review, C (Nuclear Physics); (United States), Vol. 50:4; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CALCIUM 40 REACTIONS
FRAGMENTATION
CALCIUM 40 TARGET
ANGULAR MOMENTUM
ENERGY SPECTRA
EXPERIMENTAL DATA
GEV RANGE 01-10
MASS SPECTRA
NEUTRON EMISSION
CHARGED-PARTICLE REACTIONS
DATA
EMISSION
ENERGY RANGE
GEV RANGE
HEAVY ION REACTIONS
INFORMATION
NUCLEAR REACTIONS
NUMERICAL DATA
SPECTRA
TARGETS
663450* - Heavy-Ion-Induced Reactions & Scattering- (1992-)
663540 - Nuclear Mass Ranges- A=39-58- (1992-)