development of micro-pattern gaseous detectors – gem - LMU

Chapter 8
Implementation of Highly Segmented
Strip Readout
This chapter documents the construction of a triple GEM prototype 2.0 with highly segmented anode.
The design of the detector is shown in Ch. 8.1. Two different readout systems are implemented. A
readout based on the charge integrating 16 channel GASSIPLEX chip is illustrated in Ch. 8.2. The
implementation of a readout based on 128 channel APV25 chips is reported in Ch. 8.3
8.1 Design of the Prototype 2.0
For the investigation of high spacial resolution a complete new detector was designed.
8.1.1 The Highly Segmented Anode
Fig. 8.1 shows a picture of the high-segmented anode. The anode has an overall surface of
250 × 360 mm 2 . In the multi layer production process it was possible to integrate the HV supply
lines in the board for reduction of passive material in the detector volume. We implemented three
different designs for the active area of the detector. The micro strips of all three PCBs have equal
dimension of 150 µm width and 250 µm pitch. They are made of copper and covered with a 5µm
thick lead-free tin layer. For the readout based on GASSIPLEX chips we have chosen an active area
of 90 × 100 mm 2 (Fig. 8.1) as well as a the total achievable active area of 100 × 100 mm 2 . The
detection area of an anode based on APV25 readout is 96 × 100 mm 2 . In every version of the readout
PCB the active area is surrounded by a grounded top layer; a grounded bottom layer provides
shielding. Tab. 8.1 summarizes the dimensions and numbers of strips of the different readout systems
with GASSIPLEX and APV25 frontend modules (FE), respectively. The different readout systems
are explained in the following sections.
PCB for readout with 6 GASSIPLEX FEs 7 GASSIPLEX FEs 3 APV25 FEs
active detector area 0.0090 m 2 0.0100 m 2 0.0096 m 2
Number of strips 360 400 384
Table 8.1: Dimension and numbers of micro strips of the PCB anode designed for readout systems based on
GASSIPLEX and APV25 frontends.
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