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Tracking system PNPI Status report A.Krivshich June 14, 2004 “MUON” Collaboration meeting Gatchina, Russia PowerPoint Presentation
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Tracking system PNPI Status report A.Krivshich June 14, 2004 “MUON” Collaboration meeting Gatchina, Russia. РС 1. E. ТРС . μ - muons . РС 2. Tracking system for μp-capture experiment. Proportional chambers and PC-2 Two sets of PC2 electrodes under production.

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Tracking system PNPI Status report A.Krivshich June 14, 2004 “MUON” Collaboration meeting Gatchina, Russia


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slide1

Tracking system

PNPI Status report

A.Krivshich

June 14, 2004

“MUON” Collaboration meeting

Gatchina, Russia

slide2

РС 1

E

ТРС

μ - muons

РС 2

Tracking system

for μp-capture experiment

slide3

Proportional chambers and PC-2

Two sets of PC2 electrodes under production.

It order to finish the PC2 production and start its testing we would propose to discuss and fix a possible amount of materials in the PC2 cathodes during this workshop.

  • New design of cathode.
  • Aluminum. Thickness 40m. Soft.
  • Aluminum. Thickness 40 m. Hard.
  • Aluminum. Thickness 10m. Soft.
  • Aluminized Mylar (50m).

Old design of cathode.

Diameter of wires 55m. Stainless steel.

Wire spacing is 1 mm.

slide4

Time Projection Chamber

TPC#1. It is tested about 15 months.

TPC#2. It is tested about 3 months.

TPC#3. It has to be assembled after finishing

of TPC#1 and TPC#2 tests.

slide5

Electrode

wiring

at PNPI

Frame

manufacturing

at PNPI

Ultra sound

cleaning

Dust control by

light emission in

nitrogen

TPC assembling

in clean room

Print circuit

depositing at

STU

Hydrogen

Nitrogen

Gas supply system

TPC production chain

TPC testing

in vessel

slide6

90Sr

Old (PNPI) vessel

ТРС № 1

Date of TPC birth – 18 February 2003

Туре of vessel - Old one (PNPI)

Gas admixtures

Oxygen NitrogenWater

After filling≤0.5 ppm ≤0.5 ppm≤1 ppm

One month after filling ≤1 ppm 8 ppm≤ 1 ppm

slide7

TPC#1. Stage # 1

Gas - Nitrogen

Pressure- 5 Bar

Training period- 7 days

Training results- Idc ≤ 2nA (HV = 7000V)

Testing period- 11 months

Heating conditions- 1200C; 24 hours; 4 times.

Tests duration- 5 months.

Testing results- Idc ≤ 2nA (HV = 6500V)

slide8

Outer cathode wire has been broken

in the solder point.

Chamber was disassembled.

The wire was taken out.

Chamber was assembled again.

Pressure- 10 Bar

Testing period- 10 days

TPC#1. Stage # 2

Date of start – 4 February 2004

Gas - Hydrogen

Test results- Idc ≤ 5nA (HV = 6500V)

slide9

Results of the TPC#1 electrodes

visual inspection

No traces of dust.

No dark spots on the anode.

A few light-gray spots (2-3mm diameter) have been observed on the cathode planes.

Dark current after chamber assembling

Idc ≤ 5nA (HV = 6500V)

slide11

Periodic breakdowns occurred

Breakdown current

exceeded 50A under HV=6500V.

Time interval between

the breakdowns under irradiation

by 90Sr source

67 hours …………………. HV=5300V

48 hours …………………. HV=5400V

48 hours …………………. HV=5500V

6 hours …………………. HV=5600V

Long term operation characteristics of TPC#1 under irradiation

At HV = 5200V (I = 2nA)

No breakdowns during one month

slide12

Conclusion about TPC#1.

1. The results obtained during more than one year of TPC#1 operation looks quite well. We believe that TPC design and technology of its assembling are reliable and quite promising.

2. A couple of days ago TPC#1 has been taken out from the vessel to study the reasons of breakdowns.

3. The main possible reason of the breakdown occurring is the charge accumulation on the dielectric with consequent discharge.

4. Very probable that main reason of breakdowns is some mistake during TPC assembling.

slide13

90Sr

ТРС #2

Date of TPC birth –24 March 2004

Туре of vessel - New one (PNPI+PSI)

Stage #1

Gas - Nitrogen

Pressure- 5 Bar

Training period- 3 days

Training results- Dark current is rising up/down from 0.005 to 6A at HV=5200V.

It was fixed the number of anode wire which are associated with this current.

Conclusion: take out TPC from the vessel to see

what happened.

slide14

Results of the TPC#2 electrodes

visual inspection

1.No traces of dust.

2.No dark spots on the anode.

3.One dark spot (3mm diameter)has been observed on the cathode (top) directly in front of labeled anode wire .

Date of start – 6 April 2004

(One week later)

Gas - Nitrogen, 5 Bar

Test duration - One week

Stage #2

HV=5400VHV=6300V

Neighbor wire0.6 A2.4 A

Central wire2.5 A3.0 A

Neighbor wire2.2 A3.0 A

slide15

Nitrogen. 5 Bar.

Total currant

Currant from central wire

slide16

Stage #3

Gas - Hydrogen. 10 Bar

Date of start – 14 April 2004

Testing period- 7 days

Obtained results.

1. TPC is running more unstable. First trip (10A)was at HV=4700V.

2. Current in hydrogen exceeds current in nitrogen by 2-3 times.

3. Dark current is about 20A at HV=6200V.

Conclusion: take out TPC from the vessel to see

what happened again.

slide17

Results of the TPC#2 electrodes

visual inspection

1.No traces of dust.

2.No dark spots on the anode.

3.Three dark spots have been observed on the cathodes.

3.1. Two of them are placed symmetrically with respect each other directly in front of labeled anode wires.

3.2. Diameter of top (cathode) spot increased up to about 12mm.

3.3. Diameter of bottom (strip-cathode) spot was about 7mm.

3.4. Third spot had diameter about 3mm and placed far away from mentioned above sports.

slide19

90Sr

90Sr source has been collimated

Actions

1. Cathode wires with spots have been replaced by new one.

2. TPC was assembled again.

3. Hydrogen. 10 Bar.

4. Date of start – 4June 2004

5.Testing period- 1.5 months

(till now)

6. Main cathode - HV = 25 kV

Stage #4

slide20

After taking out of cathode wires with two hot spots the dark current behavior improved significantly.

So, the point where dark current is rising up more than 100 times has been shifted from HV=4.7kV to about 5.8kV.

slide26

Summary

  • We feel ourselves quite optimistic because the life become more better.
  • At the moment we have quite good experimental facilities to perform the TPC study at PNPI. We can work with two TPC simultaneously and we do it.

2. Working characteristics of TPC#1 and TPC#2 looks quite promising. Our goal is to investigate TPC behavior, including extremely high working conditions. TPC must be reliable working device.

3. It is necessary to investigate the nature of dark spots on the cathodes and prevent their creation.

4. We are going to start production of TPC#3 and TPC#4 only after finishing of TPC#1 and TPC#2 investigations.

5. We believe that at least one of these TPC will work in the next our beam run at PSI.