V.V. Avdeichikov

Light output and energy resolution of CsI, YAG, GSO, BGO and LSO scintillators for light ions

The light output and energy resolution for the scintillators CsI(Tl), YAG(Ce), GSO(Ce), BGO and LSO(Ce) have been measured with 1H, 2H and 3He ions in the energy region ∼ 3–20 MeV/nucleon using photodiodes for the light readout. A very good energy resolution of ∼ 0.62% for 45 MeV 3He-particles has been obtained for CsI. The YAG(Ce), GSO(Ce) and LSO(Ce) crystals are non-hygroscopic, have fast decay time as main component and are well suited for experiments with high counting rates and strict timing requirements. The LSO crystal gives the best energy resolution, but reveals strong quenching for heavy ions. The GSO crystal is a good candidate for operation in UHV environment and has high stopping power, short decay time (56 ns) and moderate quenching.

New isotopes29,30Mg, 31,32,33Al, 33,34,35,36Si, 35,36,37,38P, 39,40S and 41,42Cl produced in bombardment of a 232Th target with 290 MeV 40Ar ions

Abstract 17 new nucleides: 29,30Mg, 31,32,33Al, 33,34,35,36Si, 35,36,37,38P, 39,40S and 41,42C together with other, already known nucleides, have been detected and identified in bombardment of a 232Th target with 290 MeV 40Ar ions. The charged-particle identification system combining the magnetic analysis and the ΔE−E technique has been used. The resolving power of the system was good enough to resolve isotopes of argon.

On some regularities in multinucleon transfer reactions with heavy ions

Abstract Multinucleon transfer reactions have been investigated by bombarding 232 Th and 197 Au targets with 137 MeV 16 O ions. An exponential yield dependence on the Q -values was observed for nucleon exchange reactions.

Identification of charged particles by combination of the magnetic analysis and the ΔE, E method

Abstract A new method for detecting nuclear reaction products with Z ≲ 10 is described where the combination of the magnetic analysis and the ΔE , E method has been applied. The use of a telescope consisting of thin and thick detectors in the output focus of the magnetic analyzer eliminates the ambiguity of particle identification with magnetic analyzer due to various charge states and improves the mass resolution of the ΔE , E method.

Evidence for particle instability of 10He

Abstract The cross section for 10 He production in the reaction 232 Th ( 15 N −5 protons ) → 10 He at E lab ( 15 N ) = 145 MeV has been estimated from the systematics of the cross sections for multinucleon transfer reactions. In the experiment in which, assuming the particle stability of 10 He, about 80 10 He events should be expected not even a single one has been observed. This result is interpreted as evidence for the particle instability of 10 He.

New isotopes 21N, 23O, 24O and 25F, produced in nuclear reactions with heavy ions

Abstract New isotopes: 21 N, 23 O, 24 O and 25 F have been obtained in the bombardment of a 232 Th target with 174 MeV 22 Ne ions. The reaction products were identified with a magnetic spectrometer combined with a d E d x - E detector telescope.

New isotopes 23F, 24F, 25Ne and 26Ne, produced in nuclear reactions with heavy ions

Abstract New isotopes: 23 F, 24 F, 25 Ne and 26 Ne have been obtained by bombardment of a 232 Th target with 174 MeV 22 Ne ions. The reaction products were identified with a magnetic spectrometer combined with the d E /d x , E technique.

Evidence for particle instability of 13Be and 14Be

Abstract Neutron-rich isotopes of beryllium have been produced in the bombardment of 232 Th with 15 N ions. About 20 000 events of 12 Be were detected but no effect due to 13 Be or 14 Be ions was observed, although the expected yields of these isotopes amount to 550 events and 30 events, respectively. This can be treated as evidence for particle instability of 13 Be and 14 Be.

Emission of light fragments 3H, 3He and 4He in 4He-nucleus collisions at 3.33 GeV/N kinetic energy

Abstract Inclusive cross sections for the emission of 3H, 3He and 4He at laboratory angles of 45°, 90° and 135° in collisions of 4He with targets of 9Be, 12C, 27Al, 64Cu, 108Ag and 197Au at a beam kinetic energy of 3.33 GeV/nucleon are presented. Assuming the existence of an intermediate object emitting fragments, we have found its velocity and temperature for different fragment energies. It is shown that the velocity and temperature continuously increase with the fragment energy under consideration. The evaporation mechanism is discussed, and it is argued that the evaporation significantly contributes to the yield of fragments with energy less than 50 MeV. The considered 3H to 3He ratio is found to be larger than the neutron to proton ratio in the emitting system. Comparing 3H and 3He spectra, an important role of the Coulomb barrier is shown. The At dependence of the yield of the fragments is studied. The experimental spectra are compared with thermodynamic firestreak model predictions. The model is successful in describing the emission of fragments with energy greater than 50 MeV.