8
1 Introduction
(a) Close-up of GEM construction
Pad plane
GEM 1
GEM 2
GEM 3
GEM 4
E T1
E T2
E IND
E T3
(b) TPC GEM stackup
Fig. 1.6 Left image shows an electron microscope picture of a 50 µm thick GEM foil with 70 µm
holes and 140 µm spacing [12]. Right picture shows the stackup of four GEM foils, as will be used
in the TPC
As the current readout electronics is based around a triggered readout, a full
redesign of the complete front-end chain is needed [14]. The new electronics must
implement a continuous readout scheme and should be able to handle the resulting
higher readout data rate. In addition, it should accommodate both the negative signal
polarity of the new GEM detectors and the lower gas gain, which demands a low
noise design.
1.2.2 Principal Operation of GEMs
The GEM detector is constructed of a thin foil of Kapton, clad in copper on both sides
and chemically pierced with small holes a fraction of a millimetre apart, see Fig. 1.6. A
high voltage potential is set up between the two sides of the foil, making large electric
fields in the holes. Electrons in the gas entering the hole will create an avalanche of
hundreds of electrons. By having several layers of GEMs the number of electrons can
be increased even more by providing additional stages of amplification. By offsetting
the holes between the layers, the ion backflow can be decreased significantly [12].
The electrons are collected by a suitable device, like a pad plane. A stackup as to be
used in the TPC detector can be seen in Fig. 1.6.
1.2.3 Motivation for MCH Upgrade
The triggering source for readout of the Muon Tracking Chamber is the Muon Tracking (MTR), which is currently limited to a trigger rate of 1 kHz. The design read-out
rate for Run 3 for MCH has been set to 100 kHz to have a safety margin above the
1 Introduction
(a) Close-up of GEM construction
Pad plane
GEM 1
GEM 2
GEM 3
GEM 4
E T1
E T2
E IND
E T3
(b) TPC GEM stackup
Fig. 1.6 Left image shows an electron microscope picture of a 50 µm thick GEM foil with 70 µm
holes and 140 µm spacing [12]. Right picture shows the stackup of four GEM foils, as will be used
in the TPC
As the current readout electronics is based around a triggered readout, a full
redesign of the complete front-end chain is needed [14]. The new electronics must
implement a continuous readout scheme and should be able to handle the resulting
higher readout data rate. In addition, it should accommodate both the negative signal
polarity of the new GEM detectors and the lower gas gain, which demands a low
noise design.
1.2.2 Principal Operation of GEMs
The GEM detector is constructed of a thin foil of Kapton, clad in copper on both sides
and chemically pierced with small holes a fraction of a millimetre apart, see Fig. 1.6. A
high voltage potential is set up between the two sides of the foil, making large electric
fields in the holes. Electrons in the gas entering the hole will create an avalanche of
hundreds of electrons. By having several layers of GEMs the number of electrons can
be increased even more by providing additional stages of amplification. By offsetting
the holes between the layers, the ion backflow can be decreased significantly [12].
The electrons are collected by a suitable device, like a pad plane. A stackup as to be
used in the TPC detector can be seen in Fig. 1.6.
1.2.3 Motivation for MCH Upgrade
The triggering source for readout of the Muon Tracking Chamber is the Muon Tracking (MTR), which is currently limited to a trigger rate of 1 kHz. The design read-out
rate for Run 3 for MCH has been set to 100 kHz to have a safety margin above the