Section I. Particles and Nuclei UZ0402130 ON DETERMINATION OF HYPERTRITON BINDING ENERGY FROM lHP - SCATTERING DATA Tartakovsky V.K., Fursayev A.V., Ivanova O.I. Taras Shevchenko National University, Kiev, Ukraine In a number of cases it is more rational to study structure of hypertritons by their scattering on 'H nuclei but not on complex nuclei [1]. This allows us, in particular, not to take into account the structure of target nuclei. At present it is planned to perform the corresponding experiments [2,3]. Until now there was a big uncertainty in value of the most important characteristics of ^H nuclei such as its binding energy e0 to hypertriton breakup to A-hyperon and deuteron. Due to this fact we calculated differential cross section (CS) of 3 hypertriton scattering on protons in three-cluster (A // -> A + n + p) diffraction model for medium energies versus e0. When sQ is reducing in limits of experimental uncertainty CS can increase twice or more times. This can be used for more precise definition of £0 value in the experiment. CS is 3 especially sensitive to e0 value at high energies of incident nuclei A // when large values of momentum transfer q > 4Fm"' are possible. However, at these energies, CS noticeably reduces comparing to its maximum value. The deviation of AN-interaction magnitude from NN-interaction reduces CS by 15^-20%. This becomes an additional source of information about intensity of AN-interaction. The Hulthen's wave functions wen; used in calculations for description of three-baryon system A+d and Gaussian dependences - for baryon-nucleon profile functions. All parameters were found from experimental data on baryon-nucleon interaction. 1. M.V. Evlanov, A.M. Sokolov, V.K. Tartakovsky, Yad.Fiz. - 1997. - V.60, P.444. 2. P.I. Zarubin, ECHAYa - 1995.-V.26, P.523. 3. A.I. Malakhov, Yad.Fiz. - 2002. - V.65, P.235. UZ0402131 CROSS SECTION OF EXCITED 12C* NUCLEI PRODUCTION IN 16Op-COLLISIONS AT 3.25 A GEV/C 'Bazarov E.Kh., 3Glagolev V.V., 2Ismatov E.I., 2Karshiev D.A.. ^ratenko M.Yu. 'Lugovoi V.V., 'Lutpullaev S.L., !OHmov K., 'Yuldashev A.A., 2Yuldashev B.S., 2Fazylov M.I. 1 Physical-Technical Institute of SPA «Physics-Sun»of Uzbekistan Academy of Science, Tashkent, Uzbekistan 2Institute of Nuclear Physics, Uzbekistan Academy of Science, Tashkent, Uzbekistan 3 Joint Institute for Nuclear Research, Dubna, Russia The comparison of the three a-particles production channels and that of the 12C nuclei production in the 16Op-collisions at 3.25 A GeV/c [1] showed that within the statistical errors the average multiplicities and the average momentum characteristics of the secondary fragments and charged particles produced in these two channels are similar. Also it was shown that the yield cross sections of these channels are similar. All these results proved that the both channels are realized at the similar physical conditions. The comparison of these 67 Section I. Particles and Nuclei results with the predictions results obtained from the cascade-fragmentation evaporative model [2], which considers the nuclei as an ideal fermi gas drew us to a conclusion that a- cluster structure of the oxygen-16 nucleus plays an important role at its fragmentation process. The present work is the continuation of the work [1] and is dedicated to the further analysis of the three cx-particles production channel, i.e. the reaction 16O + p-• 3ct+X, (1) where X - can single or double-charged fragment with the mass number of A<3. Besides, there can be charged pions and recoil protons, if there is no inelastic recharging of the latter to the neutron and n+. The experimental material was obtained from 1-meter hydrogen bubble chamber, irradiated at the synchrophasotron of the Laboratory of High Energies JINR by the beam of oxygen nuclei with the momentum of 3.25 A GeV/c, and is based on the analysis of more than 11000 inelastic 16Op-interactions. The secondary charged particles and oxygen nuclei fragments identification procedure is described in our previous works [1,3,4]. The aim of our work is to determine the branches of the three cc-particles production mechanisms. For this the reaction (1) simulation within the model of isotropic phase space was done. In the simulation the experimental branches of the direct (I2C* -> 3a) and cascade (12C* ->• 8Be* + a -> 3a) decays of the excited 12C* nuclei were taken into account. The comparison of the experimental dependences of the average transverse and the absolute average longitudinal momenta of a-particles on the excitation energy, defined as a AE* = M3a - 3M (M3a - the invariant and 3Ma - sum mass of the three a-particles) with the calculated results showed that they are in good agreement in the region of AE*<15 MeV. This indicates that in the region of AE*<15 MeV the excited carbon-12 nucleus can be produced from the rest three a-particles with high probability after the primary collision act leading to a decay of one of the four clusters of the 16O nucleus. Then the excited carbon-12 nucleus produces three a-particles as a result of decay. In the events with the AE*>15 MeV a-particles can be produced either from the direct fermi decay of the initial 16O nucleus after the primary collision act with proton or from the quasi-elastic beat-out of one of the three a- clusters of the weakly bound remnant-nucleus. The experimental dependences of the average total transverse and absolute average total longitudinal momenta on AE* themselves indicate the above-mentioned facts. These dependences are stronger in the region of AE*<15 lvfoB and they become weaker or represent a plateau shape at the large values of excitation energy. The distribution over the difference of the azimuthal angles between the proton and a-particle having the maximal emission angle in the event also proves the possible quasi-elastic beat-out of one of the three clusters of the remnant-nucleus by the proton of the target or the secondary particle. Basing on the analysis of the spectrum of the invariant masses of the three a-particles the branches of a-particles produced in the decay of the excited 12C* nuclei were determined. They were found to be equal to 0.38 ± 0.01. 1. M.A. Belov, K.G.Gulamov, V.V.Lugovoi et al., YaPh 65,990 (2002). 2. A.S. Botvina, A.S. Ilinov, I.N. Mishustin, Nucl. Phys. A507, 649 (1990); Multifragmentation decay of nuclei with protons of medium energy (Preprint JINR, #626), 1989. 3. A.S. Botvina, W. Wislicki, Sh. Gaitinov et al., Z. Phys. A345, 413 (1993). 4. V.V.Glagolev, K.G.Gulamov, M.Yu.Kratenko et al., Pisma v JETF 58, 497 (1993); Pisma v JETF 59, 316 (1994). 68.