Yu. Murin

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.

Thin detectors for the CHICSi /spl Delta/E-E telescope

A pilot series of 10 /spl mu/m to 15 /spl mu/m thin silicon detectors has been made for the /spl Delta/E-E telescopes in the CHICSi detector system. This system will operate at the CELSIUS heavy ion storage ring in Uppsala, Sweden. /spl Delta/E-E telescopes provide isotope identification and energy determination of fragments from nuclear collisions. The thin detectors are made as p-i-n diodes in thin etched membranes in 280 /spl mu/m thick silicon wafers. The membranes are made with anisotropic etching using 25 wt.% tetramethylammonium hydroxide (TMAH) solution. The etch speed of this solution is very uniform across a wafer. As a result detectors with uniform thickness can be produced. The etch depth varies with less than /spl plusmn/0.3 /spl mu/m over a wafer and the surface microroughness is in the range from 2 to 4 nm. Each detector has a 10.0 mm/spl times/10.0 mm active area on a 10.2 mm/spl times/10.2 mm membrane surrounded by a 1.1 mm wide supporting frame. The detectors have leakage currents in the active area of approximately 0.5 nA at 20 V. The breakdown voltage of the detectors is above 100 V. Evaluation experiments with telescopes consisting of a thin detector in combination with a thick detector have shown excellent isotope separation capabilities. Mass separation of /sup 6/Li and /sup 7/Li is clearly observable.

CHICSi - a 3pi Multi-detector System for Studying Heavy Ion Interactions Inside a Storage Ring

Abstract CHICSi — a 3π multi-detector system is presented. The setup consists of 576 ultra high vacuum compatible telescopes to study intermediate energy heavy ion as well as proton induced collisions at storage rings operating in slow ramping mode. Primary it will be installed at the gas-jet target station of the CELSIUS facility at The Svedberg Laboratory in Uppsala.

Neutron-proton interferometry in 30A MeV40Ar+197Au collisions

Abstract Neutron-proton correlation functions in 30A MeV 40 Ar + 197 Au , 12 C , CH 2 reactions have been measured. In contrast to the nn and pp correlations, which exhibit the shape expected from quantum symmetrization effects and nuclear+Coulomb (pp) final-state interaction, the np function shows much less correlation strength. This may be due to Coulomb repulsion on the proton and/or to a larger effective spin than expected. Selecting high energy nucleons strengthens both the np and pp correlations.

Intermediate mass fragment production mechanism in relativistic 4He+Au interactions

Abstract The cascade-percolation model is proposed to interpret the experimentally observed incident energy dependence of mass yield slopes for intermediate mass fragments generated in inclusive relativistic 4 He+Au reactions. A mass moment correlation analysis is performed for the more sophisticated exclusive data.

Inverse Kinematics Studies of Intermediate‐Energy Reactions Relevant for SEE and Medical Problems

The lack of systematic experimental checks on the intermediate‐energy nuclear model simulations of heavily ionizing recoils from nucleon‐nucleus collisions — critical inputs for the Single Event Effect analysis of microelectronics and dosimetry calculations including high‐LET components in the cancer tumor radiation therapy — has been a primary motivation for a new experiment planned at the CELSIUS nuclear storage ring of The Svedberg Laboratory, Uppsala, Sweden. Details of the experiment and the first results from a feasibility study are presented here.

Experimental isotopic effects in comparison to statistical prescriptions for fragment production in 32A MeV and 14A MeV 14N + 112,124Sn reactions

Results on isotopic effects in the production of light fragments in reactions of 14A and 32A MeV 14N ions with 112Sn and 124Sn are presented. The data are discussed in the frameworks of classical Weisskopf evaporation and an alternative Fermi gas prescription. The source isospin dependence of the production rates is consistent only with the latter prescription. It is emphasized that similar data from p-nucleus reactions and from projectile-like fragments in 40Ar induced reactions behave in the same way.