Test beam studies of the GasPixel transition radiation detectorprototype

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2013-04, Vol.706, p.59-64
• Main Authors: Hartjes, F., Hessey, N., Fransen, M., Konovalov, S., Koppert, W., Morozov, S., Romaniouk, A., Tikhomirov, V., Van der Graaf, H.
• Format: Article
• Language: English
• Subjects: Beams (radiation); Detectors; High rate; Inner tracker; L1 track trigger; Mathematical analysis; Micropattern detectors; Pions; Rejection; Tracking; TRD; Vectors (mathematics)
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2012.05.017

A combination of a pixel chip and a gas chamber opens new opportunities for particle detectors. These “GasPix” detectors have vector tracking features offering at the same time a L1 track trigger and a particle identification using transition radiation and dE/dX measurements. Test-beam and MC studies of tracking and particle identification properties have been performed with a GasPix prototype. The properties of the detector very much depend on the gas mixture. For one layer of the GasPix detector one can obtain a spatial accuracy down to 11μm and a vector angular accuracy of about 10mrad for a beam incident angle of 10°. For particle identification studies the detector was filled with a Xe/CO2 (70/30) mixture. A block of transition radiation radiator of 19cm was installed in front of the detector. The pion rejection power using both cluster counting and full dE/dX methods was studied. It was shown that for 5GeV particles a single layer of the detector gives a pion suppression by about a factor of 7at an electron efficiency of 90%. Two layers of this detector provide a pion rejection factor of 50 at 90% electron efficiency. A comparison of the data and MC results is presented.