T-1036: Tests of a high rate pixel detector for CMS upgrade

Many modem particle detectors require very high rate tracking capability. One example of this is the CMS tracker, and particularly its silicon pixel detector. The existing detector performs well, but will not continue to perform well as the LHC luminosity is increased. For this reason, the pixel detector will be replaced at least twice. Each new detector will be designed to operate in a higher particle fluence than the one it replaces. Both radiation tolerance and the ability to operate efficiently at high, continuous instantaneous rate are required. It is important to verify the rate capability of the new detectors and readout electronics before they are installed in CMS. The first replacement will happen around end of 2016. A new pixel readout chip was recently produced at the Paul Scherer Institute (Switzerland) to handle the foreseen high luminosity running of the LHC towards the end of the decade. High rate test beam areas are possible both at CERN and at PSI, but the beam at CERN will not be available during the upcoming LHC long shutdown and it is not possible to make precise measurements of pixel detector readout performance in the low energy pion beam at PSI. The experimenters therefore propose to test the high rate tracking capability of the new pixel detectors using the new pixel readout chip in the fall of2013 at the MT3 High Rate tracking area that is currently being developed at Fermilab. The setup will be composed of two telescopes, each containing 8 single pixel readoutchips. One telescope has the sensors planes perpendicular to the beam and in the second the planes are inclined by 20° and 30° with respect to the beam. The drift angle of the charge carriers in the magnetic field in CMS will be simulated by the 20° angle and the 30° angle corresponds to the inclination of the CMS barrel pixel. The result of these inclinations in the two directions is spreading of the charge across more than one pixel unit and thus obtaining a better position Q resolution. The two telescopes will serve to test two different features of the digital chip. In case of the zero angle telescope version, 80% of events will have a single pixel hit and the time stamp buffer will be saturated before the data buffer at high particles rates. In the inclined version the particles will produce hits in 3-5 pixels and the data buffer will saturate before the time stamp buffer. In both cases the experimenters want to measure independently at which fluence each buffer saturates. The two telescopes will be operated in a cold box in order to maintain a consistent operating temperature and to avoid thermal runaway due to an increased leakage current associated with radiation damage. A variable beam rate of 400 MHzJcm2 over~ 1 cm2 is required as well as the means to measure the rate. The experimenters will provide all the pixel detectors and associated readout electronics and data acquisition system to perform the tests.

semiconductor detector: pixel
electronics: readout
performance
CMS: upgrade
tracking detector
data acquisition
integrated circuit
benchmark
Fermilab

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Uranium in cascades is treated as enriched uranium and should be reported as material type 89. 18 TSW for T-1036 Tests ofhigh rate pixel detector for CMS Upgrade ( The following people have read this TSW: 'l- 11~ 1Michael Lindgren, Particle Physics Division t 1/-ZI~f:ific Computing Division

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