Wednesday March 04 from 14:00 to 18:00 in 40-SS-D01
 
 
1.  Rack space inventory. Patrick Ledu (Saclay)

A new version of the note describing the required number of racks has been produced. There is now a need for 98 racks in the cavern, 202 in USA15 and 97 in SCX (surface). It may happen that about 50 racks move from USA15 to the surface (LArg, Tiles and Muon RODs). In this case there will be missing place in SCX. Patrick mentioned the availability of another surface building (SDX) relativly close to SCX and which could be used. This point needs to be discussed in the T/DAQ community.
 

2. Next TTC receiver chip (TTCrx). Paulo Moreira (CERN)

Paulo presented the plans for the next version of the TTCrx. It will be a DMILL version allowing its use in any part of the detector. The option of using a radiation tolerant technology instead of a radiation hard one has been ruked out because of the time scale.
The known bugs of the previous version (non linearity in the delays, jitter variation versus the delay, temperature dependance) will be (hopefully) fixed. In addition an I2C interface will allow the user to read and write locally the different registers. This is a great improvement for ATLAS use.
The broadcast commands will be simplified: the 8-bit command will be made available for external decoding.
The package should be the same than the one developped for the current version. It is expected to have a first prototype at the end of 98 and the production available mid 99. The cost will be in the range 38-55 ChF per chip, depending on the level of tests required and on the yield.
 
 

3. Grounding scheme for the LArg calorimeter. Veljko Radeka (BNL)

Veljko presented the grounding scheme of the LArg. It is based on a fully isolated scheme (the cryostat is isolated from the solenoid and the other systems). The ground reference will be done in USA15. He listed the list of requirements to be established in conjunction with other systems (solenoid, inner tracker, inner tracker services,...) and said that there will be a document to specify each interface. The document describing the interface with the solenoid is allready available.
This presentation gave raise to a number of questions, out of which the most important was: "how do we make sure the rules are not broken?". Veljko answered that this must be and can be monitored and that putting rules and asking for discipline can only be good for the experiment. If it appears to be necessary to connect at a later stage some grounds together, it's better to do it in a controlled way instead of having connections for unknown reasons.
 

5. AOB

Ph. Farthouat summarised the work being done in the framework of the power supplies working group.
He announced that the EB recommends some changes in the dead-time: introduction of 4 empty BC after a L1A (instead of 2) and allowing LArg and TRT to introduced dead-time at 100 kHz level-1 rate (up to 4 % for a L1A latency of 2 microseconds).
Each sub-system has to provide or finalise its grounding description. A meeting will be called before the June ATLAS week and the grounding policy will be endorsed during this week.
Each sub-system is also required to provide a note describing its timing set-up strategy.