Eur. Phys. J. A 11, 297-304 (2001)

I. The properties of hot Ca-like fragments from the ⁴⁰Ca+⁴⁰Ca reaction at 35 AMeV

R. Planeta¹, W. Gawlikowicz¹, A. Wieloch¹, J. Brzychczyk¹, T. Ciszek¹, A.J. Cole², P. Désesquelles², K. Grotowski^{1, 3}, P. Hachaj¹, S. Micek¹, P. Pawlowski¹, Z. Sosin¹, D. Benchekroun⁴, E. Bisquer⁴, A. Chabane², M. Charvet², B. Cheynis⁴, A. Demeyer⁴, E. Gerlic⁴, A. Giorni², D. Guinet⁴, D. Heuer², P. Lautesse⁴, L. Lebreton⁴, A. Lléres², M. Stern⁴, L. Vagneron⁴ and J.B. Viano<sup>2

1</sup>  M. Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, 30-059 Cracow, Poland
²  Institut des Sciences Nucléaires de Grenoble, IN2P3-CNRS/ Université Joseph Fourier 53, Avenue des Martyrs, F-38046 Grenoble Cedex, France
³  H. Niewodniczanski Institute of Nuclear Physics, Radzikowskiego 152, 31-342 Cracow, Poland
⁴  Institut de Physique Nucléaire de Lyon, IN2P3-CNRS/ Université Claude Bernard 43, Boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex, France

ufplanet@cyf-kr.edu.pl

(Received: 12 March 2001 / Revised version: 18 May 2001 Communicated by D. Guerreau)

Abstract
The creation of hot Ca-like fragments was investigated in the ⁴⁰Ca +⁴⁰Ca reaction at 35 AMeV. Using the AMPHORA 4 detector system, the primary projectile-like fragment was reconstructed and its properties were determined. Both primary and secondary distributions are compared with the predictions of a Monte Carlo code describing a heavy-ion collision as a two-step process. Some of the nucleons which are identified as participants in the first step are transferred in the second step to these final states, which correspond on the average to the maximum value of entropy (thermodynamic probability). The model allows for competition between mean-field effects and nucleon-nucleon interactions in the overlap zone of the interacting nuclei. The analysis presented here suggests a thermalized source picture of the decay of the projectile-like fragment. The validity of the reconstruction procedure for projectile-like fragments is discussed.

PACS
25.70.Gh - Compound nucleus.
25.70.Lm - Strongly damped collisions.
25.70.Pq - Multifragment emission and correlations.

© Società Italiana di Fisica, Springer-Verlag 2001