12–17 Oct 2015
Trieste - Italy
Europe/Rome timezone

Effects of High Charge Densities in Multi-GEM Detectors

15 Oct 2015, 15:25
20m
Oceania (Trieste - Italy)

Oceania

Trieste - Italy

Congress Centre Stazione Marittima Molo Bersaglieri, 3 34123 Trieste Italy
Board: 36
Oral contribution MPGD Detector Physics Contributed talks

Speaker

Patrik Thuiner (CERN, Vienna University of Technology)

Description

Gaseous Electron Multipliers (GEM) are well known for stable operation at high particle fluxes. For the first time we present a study of the intrinsic limits of GEM detectors when exposed to very high particle fluxes of the order of MHz/mm^2. We give an interpretation to the variations of the effective gain, which, as a function of the particle flux, first increases and then decreases. We also discuss the reduction of the ion back-flow with increasing flux, which was first observed during studies for the ALICE Time Projection Chamber upgrade. We present measurements with a triple GEM detector, describing its behaviour in terms of accumulation of positive ions that results in changes of the transfer fields and the amplification fields. The behaviour is expected to be common to all multi-stage amplification devices where the efficiency of transferring the electrons from one stage to the next one is not 100%. Simulations, and measurements on double-stage and single-stage devices complete the discussion.

Primary authors

Mr Filippo Resnati (ETHZ / CERN) Patrik Thuiner (CERN, Vienna University of Technology)

Co-authors

Christina Streli (Technische Universität Wien) Dr Diego Gonzalez-Diaz (GSI and Tsinghua University) Ms Dorothea Pfeiffer (European Spallation Source/CERN) Eraldo Oliveri (CERN) Hans Müller (CERN) Leszek Ropelewski (CERN) Miranda Van Stenis (CERN) Dr Richard Hall-Wilton (European Spallation Source ESS AB) Rob Veenhof (RD51) Silvia Franchino (CERN)

Presentation materials