Phys. Rev. C 53, R1473 - R1477 (1996)Fusionlike reactions of 40Ar up to 1.36 GeV: Prethermalization and postthermalization particles and fragments |
M. T. Magda1, E. Bauge1,3 *, A. Elmaani1 †, T. Braunstein1, C. J. Gelderloos1 ‡, N. N. Ajitanand1, John M. Alexander1, T. Ethvignot1,3 §, P. Bier1, L. Kowalski2, P. Désequelles3, H. Elhage3, A. Giorni3, S. Kox3, A. Lleres3, F. Merchez3, C. Morand3, P. Stassi3, J. B. Benrachi3, B. Chambon4, B. Cheynis4, D. Drain4, and C. Pastor4
1Departments of Physics and Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794
2Department of Physics and Geoscience, Montclair State College, Upper Montclair, New Jersey 07043
3Institut des Sciences Nucléaires de Grenoble, Institut National de Physique Nucléaire et de Physique des Particules-Centre Nationale de la Recherche Scientifique/Université Joseph Fourier, 53 Avenue des Martyrs, 38026, Grenoble Cedex, France
4Institut de Physique Nucléaire de Lyon, Institut National de Physique des Particules-Centre National de la Recherche Scientifique/Université Claude Bernard, 43, Blvd. du 11 Novembre 1918, 69622 Villeurbanne, Cedex, France
Received 12 September 1995
Heavy residual nuclei are shown to result from the most violent (i.e., central) collisions for 40Ar + Ag reactions of up to 1.36 GeV; their average velocities are ≳80% of the c.m. velocity. Angular and energy distributions for 1,2,3H, 3,4He, and Li are measured in coincidence with these heavy nuclei. The dominant light particle components are nearly isotropic in a frame of reference having the velocity of the heavy residues. In addition there are forward-peaked high-energy components of the H, He, and Li emission attributable to prethermalization emission. Fractional abundances of these prethermalization components increase markedly with increasing incident energy. Mass and momentum balance preclude the presence of a projectilelike fragment and thus indicate fusionlike reactions with large but incomplete linear momentum transfer. The remainder of the momentum is carried away by the spray of forward-peaked ejectiles. For 1.36 GeV 40Ar∼½ of the 900 MeV available is completely thermalized, and ∼½ goes into prethermalization emission after strong collisional mixing.
©1996 The American Physical Society
URL: http://link.aps.org/abstract/PRC/v53/pR1473
DOI: 10.1103/PhysRevC.53.R1473
PACS: 25.70.Jj, 25.70.Mn, 25.70.Pq
* Present address: Centre d'Etudes de Bruyères-Le-Châtel, Service de Physique et Techniques Nucléaires, Boîte Postale No. 12, 91680 Bruyères-Le-Chatel, France.
† Present address: Battelle Memorial Institute, 505 King Avenue, Columbus, OH 43201.
‡ Present address: Physics Department, University of Colorado at Boulder, Box 446, Boulder, CO 80309.
§ Permanent address: Centre d'Etudes de Bruyères-Le-Châtel, Service de Physique et Techniques Nucléaires, Boîte Postale No. 12, 91680 Bruyères-Le-Chatel, France.
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