Welcome on triple GEM detectors R&D

Front End Electronics

One of the major issue for a GEM detector is the electronics used for the signal readout.

The electronics must have comparable performances on spatial resoulution (high density channels) and high rate capability.

In the mainframe of LHCb (CERN) experiment,  a Carioca GEM Chip has been designed and made

for the signal readout of muon station chambers M1R1, just around the LHC beam pipe.

Each chip has 8 channels with a sensitivity of  2-3 fC;

The output are timeoverthreshold LVDS signals with a typical width of  10-30 ns.

The chip is radiation tollerant; .

In Frascati we designed and made a Front End Board with two of these non-encapsulated Carioca Chips.

The final "Carioca Card" is extremely modular and usable for different GEM applications with a total dimension of 3x6 cm², with a channel density of 1 ch/cm².

On the left, two Carioca Cards have been plugged on a GEM Chamber backplane. In general we use 8 Carioca Cards for each GEM detector for a total of 128 LVDS channels.

A mother board can be easly plugged on top of the 8 Front End Boards
for the Low Voltage Power Supply and Thresholds distribution as can be seen on the right picture below.We have designed and made two type of mother boards up to now.
The first one (see the picture below) is built with 4 Robinson Nugent connectors (128 LVDS outputs )
and 4 scotchflex connector for Low Voltage power supply and Thresholds settings;
All the voltages are supplied remotely with a custom made NIM Module, called GEM LV.

The second mother board is built with an FPGA on board able to acquire the 128 LVDS signals and measure :
- the rate measured by each pads within different gates
  (Scaler readout);
- the signal arrival time realtivelly to a trigger input
  (TDC readout ) 

The "inteligent" mother board (see the picture aside) foreseen for data transfer both
one etehrnet connection  and two usb port and two optical links.
Two inputs NIM are used for trigger purposes and time gate.

Here the link to the GEMBOARD Manual