Beam test measurements on GaAs pixel detectors at various angles of incidence

Citation
W. Braunschweig et al., Beam test measurements on GaAs pixel detectors at various angles of incidence, NUCL PH B-P, 78, 1999, pp. 505-510
Citations number
6
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS
ISSN journal
0920-5632 → ACNP
Volume
78
Year of publication
1999
Pages
505 - 510
Database
ISI
SICI code
0920-5632(199908)78:<505:BTMOGP>2.0.ZU;2-8
Abstract
A GaAs pixel detector constructed in Aachen has been tested in a 4 GeV elec tron beam at DESY. The experimental setup allowed tilting the detector with respect to the beam line with angles of incidence from 0 degrees to 45 deg rees. The sensor-array consisted of 8 x 16 pixels with a size of 125 x 125 mu m(2) each. The detector was made of a 250 mu m thick Freiberger SI-GaAs wafer. An improved contact was formed on the backside, allowing safe operat ion of the detector in the soft breakdown regime. A double metal technique allowed bonding the single pixels linearly to the readout-chip. Using the t he fast PreMux128 preamplifier multiplexer chip (tau(p) = 40ns) a signal to noise ratio of 29 was obtained for a beam angle of incidence of 0 degrees increasing up to 38 for 45 degrees. The spatial resolution obtained with an angle of incidence of 45 degrees was (9.0 +/- 6.0)mu m while the resolutio n of the untilted detector is equal to the digital one (36.1 mu m). For the se testbeam-measurements the detector was connected to the electronics via wire-bonds. For future experiments bump-bonding connections are required. T he results of a process for the formation of bump-bond connections on GaAs pixeldetectors are shown.