Eur. Phys. J. A (2014) 50: 86
https://doi.org/10.1140/epja/i2014-14086-9

Special Article - Experimental Physics

Energy measurement and fragment identification using digital signals from partially depleted Si detectors

¹ Dipartimento di Fisica, Università di Firenze, via G. Sansone 1, 50019, Sesto Fiorentino (FI), Italy
² Sezione di Firenze, INFN, via G. Sansone 1, 50019, Sesto Fiorentino (FI), Italy
³ LPC, IN2P3-CNRS, ENSICAEN et Université de Caen, F-14050, Caen-Cedex, France
⁴ Institut de Physique Nucléaire, CNRS/IN2P3, Université Paris-Sud 11, F-91406, Orsay cedex, France
⁵ GANIL, CEA/DSM-CNRS/IN2P3, B.P. 5027, F-14076, Caen cedex, France
⁶ INFN-LNL Legnaro, viale dell’Università 2, 35020, Legnaro (Padova), Italy
⁷ Departamento de Fisica Aplicada, FCCEE Universidad de Huelva, 21071, Huelva, Spain
⁸ Heavy Ion Laboratory, University of Warsaw, ul. Pasteura 5a, 02-093, Warsaw, Poland
⁹ Jagiellonian University, Institute of Nuclear Physics IFJ-PAN, PL-31342, Krakow, Poland
¹⁰ INFN and Università di Bologna, 40126, Bologna, Italy
¹¹ Sezione di Napoli, INFN, 80126, Napoli, Italy
¹² “Horia Hulubei” National Institute of Physics and Nuclear Engineering, RO-077125, Bucharest, Romania
¹³ Dipartimento di Fisica, Università di Napoli “Federico II”, 80126, Napoli, Italy
¹⁴ INFN-LNS Catania, 95129, Catania, Italy

^* e-mail: pasquali@fi.infn.it

Received: 14 February 2014
Revised: 8 April 2014
Accepted: 16 April 2014
Published online: 20 May 2014

Abstract

A study of identification properties of a Si-Si ΔE-E telescope exploiting an underdepleted residual-energy detector has been performed. Five different bias voltages have been used, one corresponding to full depletion, the others associated with a depleted layer ranging from 90% to 60% of the detector thickness. Fragment identification has been performed using either the ΔE-E technique or the Pulse Shape Analysis (PSA). Both detectors are reverse mounted: particles enter from the low field side, to enhance the PSA performance. The achieved charge and mass resolution has been quantitatively expressed using a Figure of Merit (FoM). Charge collection efficiency has been evaluated and the possibility of energy calibration corrections has been considered. We find that the ΔE-E performance is not affected by incomplete depletion even when only 60% of the wafer is depleted. Isotopic separation capability improves at lower bias voltages with respect to full depletion, though charge identification thresholds are higher than at full depletion. Good isotopic identification via PSA has been obtained from a partially depleted detector, whose doping uniformity is not good enough for isotopic identification at full depletion.