U.S. ATLAS HL-LHC Upgrade Level 2 and Deputies-NSF only Management Mailing List

[mark oreglia <oreglia AT uchicago.edu>]

I had forgotten to answer question 20; her is a full set of answers

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Tile Calorimeter



20) In your documentation, you describe simplifications of the Tile 
ELMB2 motherboard.

    Can you explain what allowed this simplification and if it has any 
impact

    on the performance of the circuits?

This is related to the single brick control. The simplification is the 
decision to use a tri-state voltage control instead of counters or 
registers that turn on/off individual bricks.
This reduces the number of components needed. There is no impact on the 
performance of the circuits.



21) What is the magnetic field at that location in ATLAS?  Have the 
components been

    tested in that field?

For the fingers, we have up to 20 Gauss in normal fingers and up to 50 
Gauss in some special fingers.
The transformers we use on the bricks are rated for up to 100 Gauss.
But we also have a few inductors in the bricks.
We are planning to perform magnetic field tests on the entire LV box to 
make sure that brick’s performance
would not be affected under magnetic field.

The Main Board has already been tested in magnetic fields 20 times 
higher than the ambient field.



22) How will the experiment pilot inform the production?  Does the 
production start

    before that pilot program sees beam?

The demonstrator drawer inserted in ATLAS is primarily a field test of 
the mechanical structure, power dissipation
and ambient noise. These have all passed.  Going forward, the 
demonstrator provides a platform for testing the back-end electronics,
communication of slow controls, and trigger configurations.



23) Does the long board get extensive temperature cycling?  Are their 
hidden vias?

The Main Boards are burned-in at 60C for 5 days as part of the 
production process. We have not experienced
any temperature related failures on the 20 boards produced so far. Yes, 
there are hidden vias on this 14-layer board.



24) Are there really fuses in the low voltage power supply?

We do not have any fuses on the bricks themselves. But the 200 V input 
is being distributed to the bricks
through a fuse board in the LV Box, with individual fuses for each 
brick. There are also some fuses on
the output voltage of the bricks, which are located on the mainboards. 
These are supposed to disconnect a
faulty mainboard side from one brick.

Attachment: TileQA.pdf
Description: Adobe PDF document