ATLAS Tilecal Electronics Design Review
Design Review Issues
The following points arose from discussions
at the design review for the 3-in-1 and Mother Board.
1. Effect on 7-pole shaper of capacitance
of PMT anode and divider board, as well as component tolerances.
These stray capacitances have been measured and documented. The effect
of component tolerances has also been investigated and documented. The
schematics have been updated with the necessary tolerances.
Stray capacitances affecting the charge injection system have
also been measured.
2. Temperature analysis of 3-in-1
The operating temperature of all active components was measured in
free air. Then the temperature of the hottest component was measured in
the operating configuration with the shield cooled to its nominal operating
temperature of 19° C. Its temperature during operation
will be less than 30° C.
3. Power supply rejection factor
We have measured the power supply noise rejection
as a function of frequency. Results are characterized as the maximum noise
allowed for 0.5 ADC noise counts. A Vicor supply has been purchased. It
is well within the allowed noise range.
4. Capacitor type
Decide on specification of dielectric. There are
concerns of reliability.
Manufacturers were contacted and characteristics
Evaluate need to burn-in and the time and temperature
program for burn-in.
A one week burn-in program is planned for all completed
6. Use of Californium source for neutron
Check radiation dose from photons.
The dose from photons is less than the photon dose in the final application.
7. Single point of failure analysis
Analayze for each part of the system the possible
failure types and the implications.
8. Updates to schematics
Add voltage rating of capacitors and power of resistors.
A footnote might indicate the default values with non-default values called
Done for all schematics for Version 3.0 and later.
9. Updates to mechanical drawing of 3-in-1
Modify tolerances on mechanical drawing to be realistic.
10. Look for coherent noise on LVL1 trigger
11. Radiation tests of Mother Board before
What can be done here? Evaluation of individual
components? Preliminary tests with Version 2?