S2 — VTPC21 (GTS3EG5T)

FRS Home Page - – S2 – Pictures – Drawings – Cable Connections – TPC Electronics – Memo for preparation before beam time

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Updated November 07, 2019

Official Manual of TPC ( PDF )
Recent Log and Memo about TPC (2019) (External link)

Present Configuration (as of 2020/Oct/22)

- in a box (pocket) for the S2 vacuum chamber (GTS3EG7T)
- Window = 100 um Stainless steel (each of front and behind)
- Gap = 8 cm (drift HV = -3200 V)
- Normal orientation
- Now calibration positions should be x = -12, 0, +12 mm and y = -6, 0, +6 mm
- To have consistent track from all 4 TPCs, one could add the values on page 5 of this memo to the grid position
- Maximum allowed HV: -3200 V (drift), +1100 V (anode), -700 V (calibration, PMT).
For heavy ions, anode and PMT voltages should be much lower than the maximum values.

Status during previous beam time

2021/Feb/15-Feb/22 (12C beam, S533/BARB + EXPERT test)

- HV(anode) = +1050V, HV(drift) = -3200V, HV(grid-pmt) = -700V
- Analog raw signal around 150--200 mV. Vth(tpc module) around 45--60 mV
- Calibration file is /d/land4/sec/s533/tpc22_calib_0024.lmd (Logbook p41-43)
- Parameter sets used during experiment is found here.

2020/June/05--June/08 (proton beam, WASA000)

- Applied voltages: anode HV = +1150 V, drift = -3200 V, calib-pmt =
- Calibration file: wasa2020june_tpc22calib_[0015-0018].lmd

2020/May/xx--May/xx (Pb beam, S469, very low evenry)

2020/Apr/08--Apr/27 (Pb beam, S468, S482, S481)

- Applied voltages: anode HV = +580 V, drift HV = -3200V, fiber-PMT = -350V

2020/Feb/28--Mar/16 (Xe beam, S474, S459, S480)

- Applied voltages: anode HV = +600 V, drift HV = -3200V, fiber-PMT = -350V
- Used very short time to get the first impression about the beam poisition. Calibration grid (run0114). Parameters
- There are files with all TPC21+22+23+24, which can be used for overall check.

2020/Feb/20--Feb/26 (Kr beam, Ca fragments, Cave-C S467)

- Applied voltages: anode HV = +700 V, drift HV = -3200V.
- Used very short time to get the first impression about the beam poisition. No grid caliberation was performed.
- There are files with all TPC21+22+23+24, which can be used for calibration (if needed). Runs 92--95.

2019/Dec/09--Dec/19 (U beam)

- After changing primary beam from 40Ar to 238U.
- Applied voltages: anode HV = +550 V, drift = -3200V

2019/Nov/18--Dec/06 (Ar beam)

- Installed at S2 as TPC22.
- All signals were checked and ok, calibration scintllator double peak ?? >> to be investigated.
- Gap is 8cm. normal orientation. DL1 signal is fine (see comment in 2019-April run).
- Applied voltages: anode HV = +800 V, drift = -3200V, fiber PMT = -500V.

2019/April/1--3 (107Ag, 290MeV/u, primary beam)

- Installed at S2 as TPC21.
- Signal of TPC22-DL1 is abnormally small. Swapping cables did not work. Something in the TPC chamber should be the reason.
- Other signals are reasonable.
- Calibration scintllator was ok.
- normal orientation - We need to open this TPC after the beam time to investigate problems of DL1.

On 28/11/2023 the thresholds of the TPC raw signal were measured and the measurements are reported in Table 1.

Table 1. TPC thresholds on the discriminator/amplifier

Signals	TPC21	TPC22	TPC23	TPC24	TPC31	TPC41	TPC42
A11	no access	-73,5	no access	-144,4	-366	-154,3	-163,8
A12	-72,7	no access	-159,3	-147,6	-387	-144,9	-164,9
A21	no access	-77	-158,3	-159,9	-353	-147,8	-160,7
A22	-157,1	-76,4	-144,7	-156,1	-405	-150,1	-166,8
DL1	-112,2	-108,9	-127,3	-195,4	-83,3	-152,2	-119,9
DR1	-79,7	-77,1	-117,3	-207	-110,9	-154,7	-116,4
DL2	-184,4	-71,3	-122,7	-196,8	-64,3	-150,6	-120,9
DR2	-180	-71	no access	-190,8	-49,6	-148,2	-127

On 28/11/2023 the thresholds of the TPC Sci-Sig raw were measured and the measurements are reported in Table 2.

Table 2. TPC calibration grid values.

TPC	Threshold on discriminator	High Voltage (V)	Current at no bema (\mu A)
TPC21	-64,5	600,5	214
TPC22	-46,5	600	213,5
TPC23	-136,5	500,5	178
TPC24	-15,3	500,5	178
TPC31		330	117,5
TPC41	-49,6
TPC42	-45,6

-- NisanYaprakBenal - 2026-10-27

On 28/11/2023 the readout window of the TDC for the TPC has been moved about 1 microsecond in order to better center the events.

-- SagarRoy - 2021-06-26