Speaker
Description
Summary
The CMS Electromagnetic Calorimeter (ECAL) is divided into the Barrel (EB) and two
End-Cap (EE) calorimeters
made of 61200 and 14648 crystals, respectively. The EB is made of 36 super modules
with 1700 crystals each
and the EE of 4 DEE’s with 3662 crystals each.
In each super module 554 printed circuit boards have to be installed:
1) 68 mother boards (MB) provide the connections between the photo-detectors (APD)
and the very front
end (VFE) cards, distribute the bias voltage of the photo-detectors and part of the
low voltage
2) 340 VFE cards amplify, shape and digitize the photo-detector signals of 5
crystals each
3) 68 low voltage regulator (LVR) cards provide the required low voltages
4) 68 front end boards (FE) process the digital data of 5 VFE cards each, generate
trigger information and
perform control functions
5) 8 token ring link boards (TRLB) interface the control fibers to electrical token
rings, providing the LHC
clock as well as fast and slow control data to the FE cards
6) 2 x 68 gigabit optical hybrids (GOH) transfer the data and trigger information
to the off detector
electronics
7) Two FE cards and two GOH are used to read out the pin diodes of the light
monitoring system
8) Low voltage bus bar distributions, power cables, remote sense wires and low
voltage control cables are required
9) 12 distributed fiber patch panels bundle the fiber pigtails of the GOH into 12
way ribbons
The basic building block of the electronics is the readout of a trigger tower (a
matrix of 5 x 5 crystals)
consisting of one mother board, five VFE cards, one LVR card and one FE card. Thus
the basic test block is the test of a trigger tower. It includes verification of
the FE identifier, listing the I2C devices, initialization, parameter setting and
verification of the FE, setting of the VFE parameters, computing of the pedestal
DAC setting, measuring the pedestals, injecting test pulses into the VFE using the
integrated test pulse generators and reading of the LVR card voltages.
The installation is performed in 5 steps:
1) Installation of the mother boards and verification the connection to the photo-
detectors, followed by the
completion and test of the cooling system.
2) Mounting of the trigger tower electronics and test of each trigger tower
individually.
3) Installation of token ring boards, connection and verification of the token
rings, including the redundant
parts.
4) Installation of the gigabit optical hybrids and the distributed fiber patch
panels, followed by a repetition
of the test of individual trigger towers
5) Installation of the low voltage distribution system.
A completed supermodule is operated for about one week. The data taken during this
period are analysed to assess the system performance.
