Experiment E286 at GANIL with the DEMON detector

1. Information taken from the text of proposal (January,1997)
=== See also the updates below. ===


J.PLUTA, IFPW, Warsaw; F. HANAPPE, ULB, Bruxelles

J.C. Angelique, G. Bizard, J. Colin, D. Durand, M. Marques, B. Tamain, LPC, Caen
B. Erazmus, Ph. Eudes, F.Haddad, C. Lebrun, L.Martin, T.Kirchner, M.Assenard; SUBATECH, Nantes
O. Dorvaux, L.Stuttge, IRES, Strasbourg
B. Benoit, E. de Goes Brennand, ULB, Bruxelles
P. Duda, K. Miller, T. Pawlak, K. Wosinska, IFPW, Warsaw
E.Doroshkevich, S.Kuleshov, K. Mikhailov, A. Stavinsky, L. Vorobyev, ITEP, Moscow
R. Lednicky IPh AS, Prague

Simultaneous measurement of two-nucleon (nn, pp, np) correlations at small relative velocities is proposed. Special attention is paid to (nn) correlations as free of Coulomb effects. The physical goal of experiment is to find the space-time properties of nucleon emission dynamics in heavy-ion collisions and to clarify some related questions: sequence of particle emission, three-body Coulomb effects, deuteron production mechanism etc.

FAISCEAU PRIMAIRE(beam);Ions: 40Ar, Energies: 77 MeV/u, Cible(target): 58Ni
Nombre d'UT demand\'e: Au total: 15UT,
Dispositif ou voie de faisceau: G21 (DEMON)

2. Update: 22.08.1998.

The measurements have been performed successfully at GANIL
in July/August'98.

For the first time - two-neutron interferometry experiment is being performed at GANIL, and for the first time - DEMON detector is used - not only to measure neutrons, but also (and simultaneously), for charged particles.
A system of 63 DEMON modules has been used: 45 modules in the interferometry block placed at the emission angle interval: 6-22 degrees; 15 modules formed the block placed around 60 degrees and 3 modules were used for an auxiliary inclusive measurements.
The interferometry blocks were arranged in the layers (three in the first block and two in the second) placed in different distances from the target. This special geometry will be used for the procedure of cross-talk rejection as described in our paper: Nucl.Instr.& Meth, A411 (1988) 417. All the modules in the first interferometry block were equipped with, so called, SyReP detectors (thin plastic scintillator) in order to identify the charged particles and neutrons. Photons were rejected by the pulse shape analysis.

An important feature of this experiment is that both, neutrons and charged particles were measured by the same DEMON modules with the same Time of Flight method giving very similar registration conditions for different types of particles. It alows us to make simultaneous analysis of correlations for different two-particle systems: (nn), (np), (pp), (pd), (nd) etc.

Some details of the experimental set-up, the first (preliminary) results and some relevent photos are displayed in the figures:

E286-geometry - Geometrical configuration (scheme and photo).

E286-team - A list of persons participating directly in the experiment.

Beam-way - The way of Argon beam in the G2 experimental hall.

E286-first result - A very first result obtained by Louise Stuttge.

INPC/98-note - Note - sent to the INPC/98 Conference in Paris.

Particle separation - The quality of particle separation.

Photo-report - The photo-report of E286 experiment at GANIL.