HV needs for TOF and Trigger counters

This document summarized the HV needs for the TOF and trigger counters. The slot assignments of the HV mainframe are as follows:

HV Slot	Module	Detector	Operating conditions
0	1461P	TOF	800 - 900 V, 0.3 mA
1	1461P	TOF	800 - 900 V, 0.3 mA
2	1461P	TOF	800 - 900 V, 0.3 mA
3	1461P	TOF	800 - 900 V, 0.3 mA
4	1461P	TOF	800 - 900 V, 0.3 mA
5	1461P	TOF	800 - 900 V, 0.3 mA
6	1461P	TOF	800 - 900 V, 0.3 mA
7	1461P	TOF	800 - 900 V, 0.3 mA
8	1461P	TOF	800 - 900 V, 0.3 mA
9	1461P	TOF	800 - 900 V, 0.3 mA
10	1461N	Ring Counters	1000 V, 0.35 mA
11	1461N	Ring Counters	1000 V, 0.35 mA
12	1461N	Ring Counters	1000 V, 0.35 mA
13	1461N	Paddle Counters	1500 V, 1 mA
14	1461N	Paddle Counters	1500 V, 1 mA
15	1461N	Paddle Counters	1500 V, 1 mA

Power requirements:

The mainframe being used for the TOF and Trigger counters is the medium power model of the 1458 series. It contains a 60 A, 24 Vpower supply. With all slots filled, it is in principle possible that the power needs of the cards exceed the power supplied by the mainframe. In our application, the current requirements are well below the maximum current that can be provided by the HV mainframe.

In order to evaluate the power needs in our application, which is entire based on the model 1461 HV cards, we use the following current information for the 1461 card:

171 mA supply per mA output + 38 mA supply per channel:

Applying this information we estimate the following current needs:

• TOF:
  • 10 Cards with 12 channels per card. Requires 10*12*38 mA = 4560 mA.
  • Each channel draws 0.3 mA (maximum). Requires 120*(171*0.3) mA = 6156 mA.
  • Total current required = 4560 mA + 6156 mA = 10716 mA.
• Trigger counters:
  • Total 64 channels of HV. Requires 64*38 mA = 2432 mA.
  • Each R1924 PMT (High-eta counters) draws 0.35 mA. Requires 32*(171*0.35) mA = 1915 mA.
  • Each R329-02 PMT (Paddle counters) draws 1 mA. Requires 32*(171*1) mA = 5472 mA.
  • Total current required = 2432 mA + 1915 mA + 5472 mA = 9819 mA.

The total current required to run the TOF and the Trigger counters is thus 20.5 A, which is well below the maximum current of 60 A which can be supplied by the mainframe.