Testing of the Gated Mode for the Belle II Pixel Detector

Sumitted to PubDB: 2016-08-05

Category: Master Thesis, Visibility: Public

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Authors	Eduard Prinker
Date	Jan. 1, 2015
Belle II Number	BELLE2-MTHESIS-2016-003
Abstract	DEPFET pixel sensors offer intrinsic amplification, low mass and a very high signal to noise ratio. They form an integral building block f or the vertex detector system of the Belle II experiment, which will start data taking i n the year 2017 at the new Super- KEKB electron-positron collider in Japan. The parti cle bunch currents have a rather short lifetime in the order of 10 minutes. To keep the significantly increased luminosity of the collider constant over time, the bunch curre nts have to be topped off by injecting daughter bunches at a rate of 50 Hz. The particles in the daughter bunches produce a high rate of background (“noisy bunches”) for a sho rt period of time, saturating the oc- cupancy of the sensor. Operating the DEPFET sensor in a so far unexplored new mode (“Gated Mode”) allows preserving the signals f rom collisions of normal bunches while protecting the pixels from background signals of the passing noisy bunches. A special test board (Hybrid 4.1) is used, which cont ains a small version of the DEPFET sensor with a read-out (DCDB) and a steering chip ( SwitcherB) attached, both con- trolled by a field-programmable gate array (FPGA) a s the central interface to the com- puter. Experimental results presented in this thesi s demonstrate that the Gated Mode can be efficiently operated at full target operatio n speed of 320 MHz.
Conference	Munich