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New method for selection and characterization of single-source events in Ni+Ni collisions at 32 A.MeV; Nouvelle methode de selection et caracterisation des evenements monosource dans les collisions Ni+Ni a 32 A.MeV

Abstract

The study of heavy ion collisions, with the help of such efficient multi-detectors as INDRA, has shown the persistence of reactions leading to single-source events, up to bombarding energies higher than the Fermi one. These events could help characterizing an expected phase transition in nuclear matter. Whatever interesting they may be, the single-source events correspond to a small part of the total cross section, which makes them difficult to isolate and therefore to analyze. That is why different selection means have been tested - thanks to the 'Simon' event generator - on a simulated Ni + Ni at 32 A{center_dot}MeV sample, before any application to the INDRA experimental data. As the known methods based on global variables did not prove effective, a set of new 4-dimensional quantities has been built, whose main advantage lies in a better description of physical events. From a Discriminant Analysis performed on 625 of these new 'moments' proceeds a highly discriminant variable, called D{sub 625}. The experimental cross section associated with D{sub 625}-selected single-source events amounts to 170 mb at 32 A{center_dot}MeV. Such quasi-fusion events are shown to disappear at about 60 A{center_dot}MeV. As regards the deexcitation mode of the 32 A{center_dot}MeV Ni + Ni  More>>
Authors:
Maskay-Wallez, Anne-Marie [1] 
  1. Inst. de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France)
Publication Date:
Jul 13, 1999
Product Type:
Thesis/Dissertation
Report Number:
LYCEN-T-9969
Reference Number:
EDB-00:102816
Resource Relation:
Other Information: TH: Thesis (Ph.D); 170 refs., 113 figs., 12 tabs; PBD: 13 Jul 1999
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; G CODES; HEAVY ION REACTIONS; MEV RANGE 10-100; MULTIPARTICLE SPECTROMETERS; NICKEL; NICKEL IONS; NUCLEAR FRAGMENTATION; NUCLEAR MATTER; NUCLEAR MODELS; REACTION KINETICS; S CODES; TENSORS
OSTI ID:
20035578
Research Organizations:
Lyon-1 Univ., 69 - Villeurbanne (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR9903430004152
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
220 pages
Announcement Date:
Dec 04, 2000

Citation Formats

Maskay-Wallez, Anne-Marie. New method for selection and characterization of single-source events in Ni+Ni collisions at 32 A.MeV; Nouvelle methode de selection et caracterisation des evenements monosource dans les collisions Ni+Ni a 32 A.MeV. France: N. p., 1999. Web.
Maskay-Wallez, Anne-Marie. New method for selection and characterization of single-source events in Ni+Ni collisions at 32 A.MeV; Nouvelle methode de selection et caracterisation des evenements monosource dans les collisions Ni+Ni a 32 A.MeV. France.
Maskay-Wallez, Anne-Marie. 1999. "New method for selection and characterization of single-source events in Ni+Ni collisions at 32 A.MeV; Nouvelle methode de selection et caracterisation des evenements monosource dans les collisions Ni+Ni a 32 A.MeV." France.
@misc{etde_20035578,
title = {New method for selection and characterization of single-source events in Ni+Ni collisions at 32 A.MeV; Nouvelle methode de selection et caracterisation des evenements monosource dans les collisions Ni+Ni a 32 A.MeV}
author = {Maskay-Wallez, Anne-Marie}
abstractNote = {The study of heavy ion collisions, with the help of such efficient multi-detectors as INDRA, has shown the persistence of reactions leading to single-source events, up to bombarding energies higher than the Fermi one. These events could help characterizing an expected phase transition in nuclear matter. Whatever interesting they may be, the single-source events correspond to a small part of the total cross section, which makes them difficult to isolate and therefore to analyze. That is why different selection means have been tested - thanks to the 'Simon' event generator - on a simulated Ni + Ni at 32 A{center_dot}MeV sample, before any application to the INDRA experimental data. As the known methods based on global variables did not prove effective, a set of new 4-dimensional quantities has been built, whose main advantage lies in a better description of physical events. From a Discriminant Analysis performed on 625 of these new 'moments' proceeds a highly discriminant variable, called D{sub 625}. The experimental cross section associated with D{sub 625}-selected single-source events amounts to 170 mb at 32 A{center_dot}MeV. Such quasi-fusion events are shown to disappear at about 60 A{center_dot}MeV. As regards the deexcitation mode of the 32 A{center_dot}MeV Ni + Ni single-source events, an extensive experimental study and comparisons of the data with two reference models seem to confirm the hypothesis of a transition between fusion-evaporation and simultaneous multifragmentation mechanisms. (author)}
place = {France}
year = {1999}
month = {Jul}
}