55 research outputs found
Dynamical effects in multifragmentation at intermediate energies
The fragmentation of the quasi-projectile is studied with the INDRA
multidetector for different colliding systems and incident energies in the
Fermi energy range. Different experimental observations show that a large part
of the fragmentation is not compatible with the statistical fragmentation of a
fully equilibrated nucleus. The study of internal correlations is a powerful
tool, especially to evidence entrance channel effects. These effects have to be
included in the theoretical descriptions of nuclear multifragmentation.Comment: 13 pages, 26 figures, submitted to Physical Review
Multifragmentation process for different mass asymmetry in the entrance channel around the Fermi energy
The influence of the entrance channel asymmetry upon the fragmentation
process is addressed by studying heavy-ion induced reactions around the Fermi
energy. The data have been recorded with the INDRA 4pi array. An event
selection method called the Principal Component Analysis is presented and
discussed. It is applied for the selection of central events and furthermore to
multifragmentation of single source events. The selected subsets of data are
compared to the Statistical Multifragmentation Model (SMM) to check the
equilibrium hypothesis and get the source characteristics. Experimental
comparisons show the evidence of a decoupling between thermal and compresional
(radial flow) degrees of freedom in such nuclear systems.Comment: 28 pages, 15 figures, article sumitted to Nuclear Physics
Model-independent tracking of criticality signals in nuclear multifragmentation data
We look for signals of criticality in multifragment production in heavy-ion
collisions using model-independent universal fluctuations theory. The
phenomenon is studied as a function of system size, bombarding energy, and
impact parameter in a wide range of INDRA data. For very central collisions
(b/b_ma
A Social-Psychological Model of Human Crowding Phenomena
Previous research on crowding has generally lacked a theoretical perspective. Moreover, there has been a tendency to view crowding in terms of spatial considerations alone and a failure to distinguish between the physical condition (density) and the psychological experience (crowding). In the present discussion, a heuristic model of human crowding phenomena is proposed which permits an integration of various theoretical perspectives and the derivation of experimental hypotheses. Although the limitation of space remains as the essential ingredient of crowding, the proposed model introduces personal and social variables which have a direct bearing on a person's perception of spatial restriction as well as on his attempts to cope with this constraint. The relation between the dimensions of the model is examined in terms of social-psychological theory. Finally, a program for future research is discussed. © 1972 Taylor & Francis Group, LLC
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