Fluence dependence of charge collection of irradiated pixel sensors

• DOI: 10.1016/j.nima.2005.06.037
• Publication Date: 2005-07-06T21:15:31Z
• Authors: T. Rohe; D. Bortoletto; V. Chiochia; L.M. Cremaldi; S. Cucciarelli; A. Dorokhov; C. Hörmann; D. Kim; M. Konecki; D. Kotliński; K. Prokofiev; C. Regenfus; D.A. Sanders; S. Son; T. Speer; M. Swartz
• Keywords: Physics - Instrumentation and Detectors; detector; tracking;; radiation hardness;; lhc;; cms;; tracking;; pixel;; silicon;; radiation hardness;; detector; FOS: Physical sciences; Instrumentation and Detectors (physics.ins-det); pixel;; 01 natural sciences; 620; 03 medical and health sciences; 0302 clinical medicine; 0103 physical sciences; lhc;; cms;; silicon

The barrel region of the CMS pixel detector will be equipped with ``n-in-n'' type silicon sensors. They are processed on DOFZ material, use the moderated p-spray technique and feature a bias grid. The latter leads to a small fraction of the pixel area to be less sensitive to particles. In order to quantify this inefficiency prototype pixel sensors irradiated to particle fluences between $4.7\times 10^{13}$ and $2.6\times 10^{15} \Neq$ have been bump bonded to un-irradiated readout chips and tested using high energy pions at the H2 beam line of the CERN SPS. The readout chip allows a non zero suppressed analogue readout and is therefore well suited to measure the charge collection properties of the sensors. In this paper we discuss the fluence dependence of the collected signal and the particle detection efficiency. Further the position dependence of the efficiency is investigated.<br/>11 Pages, Presented at the 5th Int. Conf. on Radiation Effects on Semiconductor Materials Detectors and Devices, October 10-13, 2004 in Florence, Italy, v3: more typos corrected, minor changes required by the referee<br/>