Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

Nuclear Sciences 63energy of 55 to 180 MeV on RPC (developed by FOPI, HADES collaboration) at KVI, Groningen.Excellent time resolution (45ps) has been obtained. These results demonstrate feasibility of theneutron detection concept using converter plus RPCs for charged particle detection.K Boretzky†, U Datta Pramanik†, D Rossi†, K Mahata†, KD Hildenbrand†, N Kalantar-Nayestanaki†, M Kis†, L Popescu†, C Rogollet du Toit†, A Schuttauf†, H Simon†, M Vencelj†,H Wortche† for the R3B CollborationNAP2.6.1.2 Development and performance test of an axial gas ionization detectorThe axial gas ionization detector fabricated and tested in the previous report period has beenstudied more thoroughly through electrostatic calculations of induced charges and potentials. TheShockley-Ramo theorem was used to study the weighting potential so as to investigate the utilityof the Frisch grid in the design. The limitations on the proportionality of the induced charge tothe energy loss have been also studied. The detector has been upgraded for in-beam experiments.S Adhikari, C Basu, C Samanta, SS Brahmachari, BP Das, P BasuNAP2.6.1.3 Development on the PAC spectrometer for high and low temperature measurementsDevelopment on the existing four detector perturbed angular correlation (PAC) spectrometer hasbeen made for measurements at high and low temperatures. For high temperatures, a small resistivefurnace has been made which is suitable for PAC measurements up to 700 ◦ C with a temperaturestability of 1 ◦ C. In the low temperature side, a refrigerated liquid circulator has been installedwhich can go down to -88 ◦ C. An arrangement has been made to flow the liquid through the samplein the PAC set up. Now, with the present set up, it is possible to vary the sample temperaturefrom 77K up to 973K for PAC measurements.CC DeyNAP2.6.1.4 Development of an annular parallel grid avalanche counter for spectroscopyof heavy nucleiThe difficulty involved in the spectroscopic studies of the proton rich heavy trans-lead nuclei isthat the only pathway to produce these nuclei and populate the high spin states is the fusionevaporation reaction. However, more than 60% of fusion cross section goes into fission resultingin a large background of unwanted gamma rays. In order to do an exclusive measurement, it isnecessary to tag on the evaporation residues of interest. An annular, highly segmented parallel gridavalanche counter was developed for this purpose. The detector, fabricated entirely using the SINPmachine shop and the Electronics Workshop facility (EWF), was successfully tested offline withspontaneous fission source. For the fission fragments emitted from the 252 Cf spontaneous fissionsource, anode pulses of 15 - 40 mV amplitude and 1-3 ns rise time were obtained. The noise levelinside the test set up was less than 10 mV. The cross talk between the adjacent anode segments wasless than 3%. This detector will be used for spectroscopic studies of heavy proton rich trans-lead