Micro Pixel Chamber 4 - - PowerPoint PPT Presentation

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Micro Pixel Chamber 4 - - PowerPoint PPT Presentation

Aug 25, 2022 150 likes •290 views

Micro Pixel Chamber 4 MIT Oleg Bouianov, Helsinki Univ. Marina Bouianov of

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SLIDE 1

大面積Micro Pixel Chamberの開発 4

京都大学 永吉 勉 谷森 達、窪 秀利、身内 賢太朗、 竹田 敦、折戸 玲子、植野 優、 高田 淳史、岡田 葉子 Oleg Bouianov, Marina Bouianov MIT Helsinki Univ.

  • f Technology

2004年3月27日 日本物理学会年次大会 @九州大学

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SLIDE 2

Contents

  • Micro Pixel Chamber
  • Simulation study

Electron collection ( net gas gain) Electric field ( discharges)

  • Large area detector
  • Summary
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SLIDE 3

Micro Pixel Chamber (µ-PIC)

  • PCB technology
  • Pixel electrode
  • 2D readout

Detection area = 100cm2

100µm

10cm

  • 400µm pitch electrodes
  • 256 anodes and

256 cathodes

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SLIDE 4

Length along the edge [mm]

0.5mm slits position resolution σ=120µm

Performances

103 104

Gas gain

400

Anode voltage [V] A r / C2 H6 ( 9 / 1 ) A r / C2 H6 ( 8 / 2 ) Max: 1.6×104

620 Max: 1.6×104 Stable: ~6000 Gas gain

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SLIDE 5

MIP ~4 electrons / anode

Next development

Current status

  • Max gas gain >104
  • Stable operation ( >1 month)

@ gas gain ~ 6000 Next step Tracking of MIPs

  • Stable operation @ gas gain > 104
  • Detection area = 30×30cm2

Simulation study for

  • ptimization of the electrode
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SLIDE 6

Simulation

Expected performance

Maxwell & Garfield

µ-PIC … 3D structure Dielectrics

  • Maxwell

– 3D structure – Finite element method

  • Garfield

– Electron drift – Gas multiplication

Field map

MAXWELL GARFIELD

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SLIDE 7

Substrate thickness [µm] 100 10 0.2 0.5 1.0

collected

current µ-PIC

Fraction 5µm thick 200µm thick

(+) (-)

  • -
  • Efficiency

~ 40% Efficiency > 90%

Thin substrate low efficiency small signal

Dependence on substrate thickness

Drift end points

Electron collection

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SLIDE 8

200 100 E [kV/cm]

x

anode cathode e-

Field emission

Discharge

To avoid discharge: Low electric field @ cathode edge

Damaged electrode (anode) Damaged electrodes

  • f MSGC

Nagae et al., NIM A 323 (1992) 236

10µm

~ Limit of MSGC ~

High field field emission … one of the discharge mechanisms

(cathode) (anode)

~200kV/cm @ cathode edge

10µm

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SLIDE 9

Electric field

r

anode cathode

350 E field [kV/cm] 100 (GND) (600V) O

  • High electric field

@ cathode edge

  • Low electric field

@ anode top

Discharge

Thickness 5µm 100µm 200µm

Substrate should be THICK. ( > 100µm) Low gas gain

Dangerous!! Safe!!

Dependence on substrate thickness

Thin substrate …

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SLIDE 10

Maximum gas gain

Experiment Vlim = 600V (Thickness=100µm) E ~ 200kV/cm @cathode edge Thickness = 150µm Mlim > 105

Vlim [V] Mlim 600 300 1000 107 104 10 Substrate thickness [µm] 100 150 200

Vlim for each thickness Mlim

Current status

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SLIDE 11

30×30cm2 µ-PIC

9 µ-PICs on 1 substrate Single 30×30cm2 detector is feasible. ~30cm

~17cm

Center 17×17cm2 very small offset Edge region thermal expansion should be corrected

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SLIDE 12

Summary

  • Micro Pixel Chamber (µ-PIC)

– Gas gain >104 (max) – Position resolution ~ 120µm

  • Optimization of the electrode structure

– 3D simulation using Maxwell & Garfield – Thicker substrate (150µm) gas gain >105

  • Next development

– 30×30cm2 area detector – 150µm thick substrate High quality electrode gas gain >105 in near future