Speaker
Description
Summary
For the detector commissioning planned in 2007, a sector assembly of the ATLAS
muon-endcap chamber and final test at the surface for the assembled electronics
are progressed in CERN intensively.
The thin gap chamber (TGC) is used for the muon-endcap trigger system. The
muon-endcap system covers the both endcaps of the detector (1.05<abs(eta)<2.4)
to detect isolated muons and give the level-1 muon trigger signal with two ranges of
the transverse momentum (pt) of low-pt > 6 GeV/c and high-pt > 20 GeV/c.
As at least three measurement points per track is necessary to identify a muon with
even such coarse momentum estimation, there are three TGC discs per endcap
(one has three layers with triplet chambers, and the other two discs have two layers
each with doublet chambers).
Each disc has the radius of about 10 meters, for example pivot doublet disc has
the radius of 11m, and due to this huge detector size, the number of channels
become about 320,000 in total. Every disc has commonly twelve sectors. This 1/12
sector is a construction unit for the trigger muon-endcap system for both the
chambers and electronics. The sector is also the unit for the trigger and readout system.
The electronics systems mounted on a sector are the front-end ASD
(Amplifier-Shaper-Discriminator), readout chain (pipeline buffers, derandomizers and
parallel/serial converter), trigger decision logic (timing adjustment, bunch ID,
coincidence) for the level-1 low-pt muon candidate signals, miscellaneous control and
test circuits and Detector Control System (DCS). We also mount modules for high-pt
decision logic as well as readout data concentrator nearby the sector, but these are
not directly mounted on it.
Once the sector is installed in the whole ATLAS detector system in the cavern, one
cannot access easily its electronics as well as cables. We have to test the
electronics system after completion of the sector and fix or repair quickly if we
find incomplete connection of cables or damage of electronics components.
In order to check all the functionalities, it is necessary to do almost full DAQ
operation to the sector. So DAQ systems of two types are built up with being fully
compiled with the ATLAS online software framework. First one is using test pulse of
two types which our electronics can provide intrinsically, and one can find out dead
channels of electronics, incomplete connection between ASD and readout chain with
this system. Second one is using cosmic ray pulse. To build up this system, a module
called Commissioning Trigger Module (CTM) which can provide cosmic ray trigger with
coincidence of trigger decision logic is developed. With this system, one can find
out dead channels of a chamber, cable swapping of HV and readout line. We think
this cosmic ray trigger will play a very important role at the detector commissioning
stage. So far, 60% of all 320,000 channels have been already tested with only few
tens remaining dead channels.
In this presentation, we will describe the DAQ systems and mass-test procedure in
detail, and report the result of electronics test with some actual experiences.
