beam test result
DESCRIPTION
Beam Test Result. Jeewon SEO World lab fellow. T10 Beam Test . 14. Oct. ~ 20. Nov. 2009 ALICE TOF 10 gap chamber and 24 gap MRPC was tested with different percentages of SF 6 . SF 6 Property : Highly electronegative Disadvantages Expensive cost Global warming gas. 10 Gap MRPC. - PowerPoint PPT PresentationTRANSCRIPT
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Beam Test Result
Jeewon SEO
World lab fellow
![Page 2: Beam Test Result](https://reader036.vdocuments.net/reader036/viewer/2022081507/56816257550346895dd2a772/html5/thumbnails/2.jpg)
T10 Beam Test 14. Oct. ~ 20. Nov. 2009ALICE TOF 10 gap chamber and 24 gap MRPC
was tested with different percentages of SF6.SF6
◦ Property : Highly electronegative◦ Disadvantages
Expensive cost Global warming gas
![Page 3: Beam Test Result](https://reader036.vdocuments.net/reader036/viewer/2022081507/56816257550346895dd2a772/html5/thumbnails/3.jpg)
10 Gap MRPC Gap size : 250 ㎛
Aluminum box volume : 200ℓ Gas flow rate : 20ℓ/h (O2 content was kept at 100 ppm)
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Beam Test Setup
-5GeV/c beam of π-, μ- . Trigger selected 10 ㎜ⅹ 10 ㎜ beam spot
(130 triggers/spill in every 20 seconds)
![Page 5: Beam Test Result](https://reader036.vdocuments.net/reader036/viewer/2022081507/56816257550346895dd2a772/html5/thumbnails/5.jpg)
Data Acquisition
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Slewing Correction
Time = Tchamber – Tave Tave : average time of the timing scintillators
![Page 7: Beam Test Result](https://reader036.vdocuments.net/reader036/viewer/2022081507/56816257550346895dd2a772/html5/thumbnails/7.jpg)
Time Resolution
σres = √( σch2-σsc
2)
σres : time resolution σch : measured time of signals σsc : jiter of scintillators
Ave(S1,S2)-Ave(S3,S4)
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Efficiency and Streamer Plateau
SF6 0 % 2 % 4 % 6 % 8 % 10 %Streamer
free and ef -ficient >90%
operation range
10.6~11.6 kV
10.8~13 kV
11~13.2 kV
11.2~13.4 kV
11.4~13.6 kV
11.6~13.8 kV
1 kV 2.2 kV 2 .2kV 2.2 kV 2.2 kV 2.2 kV
The knee of the effi-ciency plateau moves to high voltage when the percentage of SF6 in-crease.
Breakdown at 11.8 kV with the pure freonBreak down at
11.8kVwith pure freon
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Time resolution with various percentage of SF6
Time resolution is independent of the fraction of SF6.
![Page 10: Beam Test Result](https://reader036.vdocuments.net/reader036/viewer/2022081507/56816257550346895dd2a772/html5/thumbnails/10.jpg)
24 Gap MRPC
160 ㎛ gaps (total thickness : 3.84 ㎜ )
Gas flow rate : 20ℓ/h (box volume : 30ℓ)
-> O2 content was kept at
20 ppm
Threshold : 40 fC
![Page 11: Beam Test Result](https://reader036.vdocuments.net/reader036/viewer/2022081507/56816257550346895dd2a772/html5/thumbnails/11.jpg)
Data Acquisition
NINO mounted on chamber inside gas volume
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Compare time of one MRPC with another
Time resolution obtained by measuring time difference between two chambers
Timing scintillators are not used.
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Efficiency and Time resolution
Tdiff = (Tmean)MRPC1-(Tmean)MRPC2
The best resolution is 20.8 ps with pure freon and 19.1 ps with added 5% SF6.
Efficiency plateau is shifted to a lower voltage with the pure freon.
The streamer-free and efficient operation range
Pure freon : 1.6 kV (10.6kV ~ 12.2kV)
5% SF6 : 2 kV (11kV ~ 13 kV)
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Conclusion 10 gap MRPC
◦ Break down at 11.8kV with pure freon.◦ Work with 2% SF6, obtaining the time resolution below 50 ps with a
2.2 kV range.-> Seems to need the SF6 to avoid breakdown
24 gap MRPC◦ Work satisfactorily with pure freon
SF6 effect◦ Shift the efficiency plateau to a higher voltage ◦ Shift in streamer production to higher voltage◦ For 24 gap MRPC, the efficient operation range without streamer is
broader when SF6 added.
Time resolution is independent of SF6 fraction.