Performances of keystone geometry micro-strip gas chambers

Abstract The performances of micro-strip gas chamber detectors with CF 4 counting gas have been tested with a 241 Am α source. The behaviour of the gain as a function of gas pressure, the dependence of the energy resolution on gas pressure and anode voltage, and the gain variation along the strip length due to the keystone geometry of the micro-strip pads are reported. An empirical response function to describe such a position dependence of the gain is proposed

Isotope analysis in central heavy ion collisions at intermediate energies

Symmetry energy is a key quantity in the study of the equation of state of asymmetric nuclear matter. Heavy ion collisions at low and intermediate energies, performed at Laboratori Nazionali di Legnaro and Laboratori Nazionali del Sud, can be used to extract information on the symmetry energy coefficient Csym, which is currently poorly known but relevant both for astrophysics and for structure of exotic nuclei.Comment: 2 pages, 1 figure. Proceedings of 7th International Conference on Radioactive Nuclear Beams (RNB7), to be published in The European Physical Journal

Više-fragmentna tvorba u reakcijama 32S+58,64Ni NA 11 A MeV

The characteristic features of the 32S+58,64Ni reaction at 11 A MeV have been investigated to evidence the possible rise of multi-fragmentation processes at low excitation energies. The importance of such phenomena consists in the fact that they could represent the signature of a nuclear phase transition from a liquid to a gas region. Evidence of multi-fragment production is displayed by the present data; even if the yield of such events is compatible with the predictions of statistical models, the partition of the mass of the decaying system cannot be easily reproduced. Some preliminary indications of isospin effects are suggested by looking at the differences between the two reacting systems.Istraživali smo značajke reakcije 32S+ 58,64Ni na 11 A MeV radi pronalaženja mogućeg porasta više-fragmentnih procesa na nižim uzbudnim energijama. Važnost se tih pojava sastoji u tome što bi one mogle predstavljati znakove nuklearnog faznog prijelaza od tekućeg u plinsko stanje. Znakovi tvorbe više fragmenata vide se u dobivenim podacima; no čak ako je i prinos tih događaja u skladu s predviđanjima statističkog modela, razdioba mase sustava koji se raspada ne uspijeva se objasniti. Usporedba dviju reakcija ukazuje na moguće izospinske efekte

Mass and charge identification of fragments detected with the Chimera Silicon-CsI(Tl) telescopes

Mass and charge identification of charged products detected with Silicon-CsI(Tl) telescopes of the Chimera apparatus is presented. An identification function, based on the Bethe-Bloch formula, is used to fit empirical correlation between Delta E and E ADC readings, in order to determine, event by event, the atomic and mass numbers of the detected charged reaction products prior to energy calibration.Comment: 24 pages, 7 .jpg figures, submitted to Nucl.Instr.

Excitation of the dynamical dipole in the charge asymmetric reaction 16O+ 116Sn

Abstract The γ -ray emission from the dynamical dipole formed in heavy-ion collisions during the process leading to fusion was measured for the N/Z asymmetric reaction 16 O + 116 Sn at beam energies of 8.1 and 15.6 MeV/nucleon. High-energy γ -rays and charged particles were measured in coincidence with the heavy recoiling residual nuclei. The data are compared with those from the N/Z symmetric reaction 64 Ni + 68 Zn at bombarding energies of 4.7 and 7.8 MeV/nucleon, leading to the same CN with the same excitation energies as calculated from kinematics. The measured yield of the high-energy γ -rays from the 16 O-induced reaction is found to exceed that of the thermalized CN and the excess yield increases with bombarding energy. The data are in rather good agreement with the predictions for the dynamical dipole emission based on the Boltzmann–Nordheim–Vlasov model. In addition, a comparison with existing data in the same mass region is performed to extract information on the dipole moment dependence

On-line production of neutron rich isotopes from uranium carbide targets

Experiments done using on-line mass separation of neutron-rich nuclei produced by 1 GeV proton beam on natural U by spallation reactions are performed to study the characteristics of different UCx targets. Special attention is devoted to reliably extract isotopic yields in case of complex decay schemes and to the valuation of release efficiency of some isotopic chains. New gamma-branching measuremet for 92Rb are obtained. In addition, a formalism is developed to disantangle the contribution of β-decay in the target from direct production by fission and to provide more consistent data for the interpretation of release curves. Some results are shown for the Cs and Rb isotopic chains

Calibrating the CsI(Tl) detectors of the GARFIELD apparatus

17nonenoneU.ABBONDANNO; M.BRUNO; G.CASINI; R.CAVALETTI; S.CAVALLARO; M.CHIARI; M.DAGOSTINO; F.GRAMEGNA; A.LANCHAIS; MARGAGLIOTTI G.V.; P.F.MASTINU; P.M.MILAZZO; A.MORONI; A.NANNINI; A; ORDINE; G.VANNINI; L.VANNUCCIU., Abbondanno; M., Bruno; G., Casini; R., Cavaletti; S., Cavallaro; M., Chiari; M., Dagostino; F., Gramegna; A., Lanchais; Margagliotti, Giacomo; P. F., Mastinu; P. M., Milazzo; A., Moroni; A., Nannini; A, Ordine; G., Vannini; L., Vannucc