Beam test measurements on GaAs pixel detectors at various angles of incidence
✍ Scribed by W. Braunschweig; J. Breibach; D. Gräßel; St. König; Th. Kubicki; K. Lübelsmeyer; C. Rente; Ch. Röper; R. Siedling; O. Syben; F. Tenbusch; M. Toporowski; W.J. Xiao
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 395 KB
- Volume
- 78
- Category
- Article
- ISSN
- 0920-5632
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✦ Synopsis
A GaAs pixel detector constructed in Aachen has been tested in a 4 GeV electron beam at DESY. The experimental setup allowed tilting the detector with respect to the beam line with angles of incidence from 0 ° to 45 °. The sensor-array consisted of 8 x 16 pixels with a size of 125 x 125#m 2 each. The detector was made of a 250#m thick Freiberger SI-GaAs wafer. An improved contact was formed on the backside, allowing safe operation of the detector in the soft breakdown regime. A double metal technique allowed bonding the single pixels linearly to the readout-chip. Using the the fast PreMux128 preamplifier multiplexer chip (~-p = 40ns) a signal to noise ratio of 29 was obtained for a beam angle of incidence of 0 ° increasing up to 38 for 45 °. The spatial resolution obtained with an angle of incidence of 45 ° was (9.0 4-6.0)/~m while the resolution of the untilted detector is equal to the digital one (36.1/~m). For these testbeam-measurements the detector was connected to the electronics via wire-bonds. For future experiments bump-bonding connections are required. The results of a process for the formation of bump-bond connections on GaAs pixeldetectors are shown.