There are 4 TPCs in BRAHMS two in the forward spectrometer and two in the mid-rapidity arm, named TPM1, TPM2 , T1 and T2.

This page contains some information about these TPCs, listed below:

1. Hardware parameters
2. Scematic overview
3. Design considerations and documents
4. Construction
5. Software and test results
6. Operational procedures
7. Repair work after the enginering run 1999

The following table is a summary of some of the hardware parameters:

TPC	Anode dia [micron]	Anode pitch [mm]	Dist to pad [mm]	Pad pitch [mm]	Pad length [mm]	Row pitch [mm]	Dist cathode to cathode [cm]
TPM1	15	30.5	3.	3.9	30.0	30.5	22.0
TPM2	15	5	4.5	4.7	24.	25.0	21.8
T1	15	4	4.5	3.5	29.	40.0	21.8
T2	15	4	4.5	3.5	29.	40.0	21.8
NEW TPM1	15	5.084	3.	3.9	30.0	30.5	21.8

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The diagram above shows the wire arrangement for all TPC except the original version of TPM1.

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Design Considerations and Documents

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Construction

The field cage of TPM1 (designed in France).

A construction drawing of TPM2 is usefull for reference. All lengths are measured in cm. (The complete drawing is also available, but this is a big one.)

The mounting of connectors on the pad planes required some ingenuity, the following pictures should help people analysing data from the TPCs FEE card to pad connections in T1

The final version of the FEE cards have been received, and mounted on MTP1 in the laboratory at BNL. A brief report on the setup and temperature measurements can be found as a pdf file

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Software and test results

• A userguide and documentation for the BRAHMS PadMonitor program can be found here .
• Pad monitor screen capture of a cosmic ray event in MTP1 taken April 8, 1999.
• Data file cosmics.tar.gz from which the above event was taken.
• Pad Monitor executable padm compiled on sun2.hirg.bnl.gov 9-Apr-1999.
• Performance analysis of T1 based on cosmics taken November 1999 - January 2000 (Jens Ivar Jørdre, Bergen, diploma thesis).

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Operational procedures

• Operational parameters for MTP1 and MTP2 are briefly described in this document (pdf) by Francs Jundt.
  
  
• Cabling for T1, including gating grid pulser, is summarized in the following table:

  [T1]	Cable #	Power supply #	Slot channel	Typical HV [V]	Typical current
  Anode	5	L1458A	1.5	1250	< 50 nA
  Field shaper	** grounded **			0	< 50 nA
  Drift voltage	1	L1458A	7.6	-4980	61.5 uA
  Gating grid -	2	M4	19	-260
  Gating grid ref.	3	M4	18	-180
  Gating grid +	4	M4	17	-100

  
  
• Cabling for T2, including gating grid pulser, is summarized in the following table:

  [T2]	Cable #	Power supply #	Slot channel	Typical HV [V]	Typical current
  Front: Anode	8	L1458A	1.6	1250	< 50 nA
  Front: Field shaper	6	L1458A	3.6	0	< 50 nA
  Rear: Anode	9	L1458A	1.7	1250	< 50 nA
  Rear: Field shaper	7	L1458A	3.7	0	< 50 nA
  Drift voltage	1	L1458A	7.7	4980	59.3 uA
  Gating grid -	2 (labeled tpc2)	M4	25	-260
  Gating grid ref.	4	M4	24	-180
  Gating grid +	5	M4	23	-100

  
  
• Cabling for TPM1, including gating grid pulser, is summarized in the following table:

  [TPM1]	Cable #	Power supply #	Slot channel	Typical HV [V]	Typical current
  Anode	5	L1458A	1.0	1200	60 nA
  Field shaper	** grounded **
  Drift voltage	1	L1458A	7.2	-4980	45 uA
  Gating grid -	2	M4	13	-260
  Gating grid ref.	4	M4	14	-180
  Gating grid +	3	M4	15	-100

  
  
• Cabling for TPM2, including gating grid pulser, is summarized in the following table:

  [TPM2]	Cable #	Power supply #	Slot channel	Typical HV [V]	Typical current
  Anode	5	L1458A	1.1	1280	< 50 nA
  Field shaper	** grounded **
  Drift voltage	1	L1458A	7.1	4980	57.5 uA
  Gating grid -	2	M4	22	-260
  Gating grid ref.	4	M4	21	-180
  Gating grid +	3	M4	20	-100

  
  

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Repair work after the Engineering Run (July-Aug 1999)

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