Joint Institute for Nuclear Research Relativistic ... - Index of - JINR

HIGH ENERGY PROTONS FROM 12 C FRAGMENTATION
B.M.Abramov, P.N.Alexeev, Yu.A.Borodin, S.A.Bulychjov, I.A.Dukhovskoi, A.I.Khanov,
A.P.Krutenkova, V.V.Kulikov † , M.A.Martemianov, M.A.Matsuk, E.N.Turdakina
Institute for Theoretical and Experimental Physics, Moscow
† E-mail: kulikov@itep.ru
Results of the FRAGM experiment performed at the ITEP heavy ion Tera-Watt-
Accumulator are presented. Fragmentation of 12 C nuclei on Be-target was studied at six
energies 0.2, 0.3, 0.6, 0.95, 2.0 and 3.2 GeV/nucleon. Fragments were registered at 3.5 o
by double focus beam line spectrometer with scintillation counters and were separated by
dE/dx and TOF measurements. Main attention was given to high momentum protons in
cumulative region where x>1 (x = p/p 0 and p(p 0 ) - proton (projectile) momentum per
nucleon). The obtained x-spectra cover up to six orders of invariant cross section magnitude
and up to 2.4 in the x value. These spectra were analyzed in multiquark cluster
model with fragmentation functions given by Quark-Gluon Strings model. In the framework
of this analysis we estimated relative probabilities of six- and nine-quark clusters
in comparison to single nucleon component in 12 C. These probabilities were found to be
about 10% and 0.5% respectively. The values are in qualitative agreement with estimation
of two- and three-nucleon short-range correlation probabilities in 12 C nuclei made in
(e,e’) experiment at TJNAF. In purely phenomenological approach we fitted proton kinetic
energy spectra in a rest frame of projectile nucleus with two exponents and obtained
the temperatures in evaporation and cumulative regions from the slope parameters. At
studied energies the temperature in the cumulative region rises with projectile energy but
is still smaller than measured in pA-interactions at high energy. Target dependence of
these temperatures was measured with high precision at 0.3 GeV/nucleon for Be, Al, Cu
and Ta and showed independence from target material.
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