Hans Rudolf Schmidt

Development of a GEM based detector for the CBM Muon Chamber (MUCH)

The characteristics of triple GEM detectors have been studied systematically by using cosmic ray muons. The minimum ionizing particle (MIP) spectra have been taken for different GEM voltage setting. Efficiency of GEM detector has been measured for cosmic ray. At high rate operation of GEMs the value of the protection resistor influences the gain and the stability. This feature has been investigated varying both the rate and the value of the protection resistor. This measurement has been performed using both X-ray generator and Fe55 source. The ageing and long-term stability of GEM based detectors has been studied employing both X-ray generator and Fe55 source. The ageing study of one GEM module is performed by using a 8 keV Cu X-ray generator to verify the stability and integrity of the GEM detectors over a longer period of time. The accumulated charge on the detector is calculated from the rate of the X-ray and the average gain of the detector. The details of the measurement and results has been described in this article.

Systematic measurements of the gain and the energy resolution of single and double mask GEM detectors

Abstract Systematic studies on the gain and the energy resolution have been carried out by varying the voltage across the GEM foils for both single mask and double mask triple GEM detector prototypes. Variation of the gain and the energy resolution has also been measured by varying either the drift voltage, transfer voltage and induction voltage keeping other voltages constant. The results of the systematic measurements have been presented.

The ALICE TPC: Status and perspectives

The ALICE TPC is the largest Time Projection Chamber ever built. Given the performance requirements it is also, and justifiably so, dubbed the most challenging one. In this paper we browse through the often contradictory optimization strategies and outline the solutions taken to meet the specifications. Mainly on the basis of the commissioning data taken in 2008 and 2009 we will examine to which extend the ALICE TPC came up to its performance expectations, which were outlined elsewhere [1, 14]. First results on the performance of the TPC with proton-proton collisions in December 2009 are presented.

J/psi production as a function of charged particle multiplicity in pp collisions at root s=7 TeV

The ALICE Collaboration reports the measurement of the relative J/psi yield as a function of charged particle pseudorapidity density dN(ch)/d eta in pp collisions at root s = 7 TeV at the LHC. J/psi particles are detected for p(t) > 0, in the rapidity interval vertical bar y vertical bar 0. In the highest multiplicity interval with (dN(ch)/d eta)(bin)) = 24.1, corresponding to four times the minimum bias multiplicity density, an enhancement relative to the minimum bias J/psi yield by a factor of about 5 at 2.5 < y <4 (8 at vertical bar y vertical bar < 0.9) is observed