Search

The processes of excitation and decay of high excited 5He resonances into the d + t channel have been studied in the reaction 7Li(d, α)5He* at the energy of deuteron beam Ed = 37 MeV. In the inclusive spectra of α-particles in addition to the contributions of well known 5He resonances, the high excited states with excitation energies Ex ~ 19 and Ex > 20 MeV were observed. Cluster decay of these resonances was also identified in αd- and αt-coincidence spectra. For the first time, the decay into the d + t channel was observed for 5He resonances with Ex = 22 and 26 MeV. The determined resonance energy and width are partly agreed with the R-matrix analysis of data obtained at the study of d + 3H and n + 4He binary reactions. The possible Coulomb effects in three-particle channels of reaction 7Li(d, α)5He* are also analyzed for different conditions of observation of high excited 5He resonances.

The decay properties of nuclear unbound states formed in the reactions with three particles in the final state are reviewed. The modification of resonance parameters observed in these reactions and caused by the influence of the Coulomb field of accompanied particles is analyzed for the resonances with excitation energy near and far from the decay threshold.

Measurements of differential cross-sections of α-particle inelastic scattering by 7 Li nuclei and 7 Li(α, α6 Li)n, 7 Li(α, αα)t reactions have been performed at the energy Eα = 27,2 MeV. Probability of 7 Li*(7,45 MeV) decay into 6 Li + n channel has been determined from the ratio of cross-sections measured in kinematically complete and incomplete experiments. The large discrepancy of this value (P = 0,49 ± 0,06) and of those obtained at the study of 7 Li*(7,45 MeV) decay in binary reactions can be explained by the influence of Coulomb field of accompanied αparticle on the decay of near-threshold resonances in three-particle reactions.

The processes of formation of stable and unstable states of 3-6He recoil nuclei in the exit channels of reactions 7,6Li(d, 3,4,6He) have been studied in kinematically complete and incomplete experiments at deuteron energy of 37 MeV. The excitation cross-sections of ground and the number of excited states of these nuclei have been determined. The possible mechanisms of continuum formation in inclusive spectra of 3,4,6He nuclei have been also studied. The probability of decay of resonance 5 He*(16,75 МеВ) into d + t channel in reaction 7 Li(d, 4 He)5 He has been determined from the analysis of inclusive and exclusive experiments. Obtained data essentially differs from that obtained at the study of binary reactions.

At deuteron energy of 37 MeV the 6 He inclusive spectra are measured in the exit channel of reaction 7 Li(d,6 He)3 He. The resonance-like structure of spectra in the range of 6 He energies corresponding to the excitation of 3 He recoil nuclei in the range of E* = 6…16 MeV was observed. The experimental data can be described in assumption of existence of 3 He resonances with excitation energies of Е* = 9, 13 and 16 МеV. An analysis of the experimental spectra shows that observed structure of 6 He spectra can be as well explained by the more probable processes of excitation and decay of 7 Li and 7 He unbound states in accompanied reaction channels.

The double-sided silicon microstrip detector prototypes with 50 μm pitch developed together with CiS, Germany, have been characterized in a 2.4 GeV/c proton beam at COSY, Forschungszentrum Jülich, Germany. Data analyses including reconstruction of 1-strip and 2-strip clusters have been performed. We have done the study of charge sharing in the interstrip gap. In particular it was found that there is a charge loss of less than 10 % in the interstrip gap. The calculated signal-to-noise ratio is around 19 for the p-side of the sensor and it is sufficient for hit reconstruction. Also the charge sharing function which allows more precise determination of the hit position in silicon sensor, have been reconstructed.