Minutes of the Power Supplies Working Group 05-December-97

Presents: B. Allongue (CERN-ECP/ESS), J. Bohm (Prague, SCT), R. Chadelas (Clermont, Tiles), G. Dumont (CERN, ECP/ESS), Ph. Farthouat, M&J Givoletti (CAEN), Z. Hajduk (CERN, TRT), Piotr Malecki (Cracow, SCT), R. Richter (CERN, Muons), Francois Vazeille (Tiles)
 

1. Organisational matters.
A working group on power supplies has been set-up with a representative of each sub-system. They are:

This group should first gather the requirements of each sub-system and whenever possible and desirable, extract common elements. It should also co-ordinate the measurements made with different components concerning their radiation hardness and their ability to work in magnetic field. It should also co-ordinate the contacts with the manufacturers.
One can identify works to be done in the near future:
(1) Establish a list of standard elements to be tested in radiation environment and the test procedures to be applied,
(2) Same for magnetic field,
(3) Start writing common specifications.

The frequency of the meeting should be of the order of 4 per year and should be organised during one of sub-system week.
The next one will be on Friday January 30, 1998.

2. Sub-systems presentations.
Most of the material is available in the FE electronics coordination page.
In the cavern, the magnetic field may be between 300 and 1000 Gauss and the radiation levels are (for 10 years of operation):
    - 10 Gy and 5 10^11 to 10^12 N.cm^-2
A summary of the requirements are given in the following table:
 
 
Sub-system
# of multivoltages units
Nominal Volt and Amps 
PIXELS 2600 1.5 V, 1.5 A
3V, 2A
10 V, 0.01 mA
500 V, 2 mA
SCT 4088 1 V, 6 mA
3.5 V, 1 A
4 V, 250 mA
7 V, 6 mA
10 V, 0.01 mA
300 V, 4 mA For n-on-n detector.
TRT 1350 3.3V, 6A
- 3.3 V, 3 A
5 V, 1 A
HEC 320 -3 V, 100 mA
4 V, 500 mA
8 V, 1 A
TILES (1) 256 5 V, 500 mA High voltage distributors
15 V, 500 mA
- 15 V, 500 mA
TILES (2) 128 5 V, 20 A Read-out Barrel
-5 V, 10 A
9 V, 400 mA
TILES (3) 128 5 V, 14 A Read-out Extended Barrel
- 5 V, 7 A
9 V, 300 mA
 
All these units should be floating and controlled through a field-bus interface, preferably CAN-bus. Some interlock should be foreseen with the cooling system.

The SCT has already a fairly detailed block diagram of their power supplies  and one has been irradiated with 1.3 10^10 N.cm^-2 and 2.5 Gy (gamma) without exhibiting any failure. They also consider the use of a shield (40 to 50 cm of polyurethylene) to decrease the radiation level of fast neutrons by two orders of magnitude.

ZH presented an evaluation of extra cost in cables which would be introduced if one has the PS of the TRT in USA15. This exercise should be repeated for other sub-systems.

3. Manufacturers presentations.
CAEN and DPS were present. Both of them are designing power supplies (high and low voltages) and expressed their interest in collaborating with us. A first step will be to try to understand with them what are the elements in our requirements which are driving the cost.

4. Work.
- Someone has to write down irradiation test procedure. R. Richter to look at it. Prague will continue an irradiation of existing LV prototypes for SCT.
- Same for magnetic field. Ph. Farthouat to look at it with the CERN electronics pool.
- Z. Hajduk to start compiling the requirements and to contact manufacturers.
- Sub-systems to evaluate the cost of extra cables if the PS are in USA15.