development of micro-pattern gaseous detectors – gem - LMU

8.2. Prototype 2.0 with GASSIPLEX Based Readout 81
Triple GEM
prototype 2.0
1
52
53
113
308
360
protec.
circuit
1
protec.
circuit
2
protec.
circuit
6
FE 1
FE 2
FE 6
bus card
trigger
DATA
Readout
Control
config.
busy
low voltage
supply
busy
Detector
Trigger
Unit
Readout
Controller
RIO2
VME
trigger
Ext.
Trigger
(TTL)
Scintillator 1 & 2
Coincidence unit
PC
Delay
NIM TTL
ELab
Figure 8.5: Schematic of the components for the readout system based on GASSIPLEX ASICs. The frontend
modules are connected to the detector via additional protection circuits on the left. The data is further processes
via bus cards to the readout controller. The coincidence of the scintillators provides the trigger [Bort 10].
of the electronics. A temporal storage of up to 15 events is possible on the FEs. Since no internal
trigger exists on the frontend modules the data is readout if the readout controller (RC) receives a
trigger from the detector trigger unit and transmits it to the FEs via the bus cards. The low voltage
of the frontends is supplied by an external module. In Fig. 8.5 the bus cards are only schematically
shown; in reality two bus cards are needed to readout the detector since four FEs are supplied by one
bus card. Additionally, the readout controller is responsible for the frontend configuration and sets
e.g. the mapping of the channels and thresholds of the individual channels. The detector trigger unit
receives an external trigger, created in the conventional trigger scintillator coincidence, as already
used in the setup of prototype 1.0 (see Ch. 3.4.1). Since the GASSIPLEX frontends have an intrinsic
shaping time of 550 ns acting as a delay, the trigger has to be transmitted 550 ns after the particle’s
passage trough the detector system.
This assembly was implemented during the last days of this thesis. The GEM prototype 2.0 was in a
table top setup with three MICROMEGAS detectors in order to build a stand alone tracking station
for cosmic muons. Recent measurements reveal a spatial resolution of
79 ± 5µm . (8.1)
The spatial resolution is limited by multiple scattering of the mostly low energetic cosmic muons and
is expected to become considerably better in a high energy muon beam [Bort 10].