Micro Pixel Chamber Operation with Gas Electron Multiplier Kyoto University dept. of physics Cosmic-ray group y g p K. Hattori Co te ts Contents 1. μ -PIC (Micro Pixel Chamber), micro-TPC (Time Projection Chamber based on μ -PIC) 2. For detection of MIPs μ -PIC + GEM (gas electron multiplier) μ (g p ) 3. Performance of GEM + μ -PIC TPC 4 Summary 4.Summary 7 th International Conference on Position Sensitive Detectors
Advanced Compton Camera p based on Micro Pixel Chamber(µ-PIC) sub MeV ~ MeV gamma-ray Compton scattering is dominant micro-TPC micro TPC energy and track of a recoil electron scintillator (surrounding micro-TPC) scintillator (surrounding micro-TPC) energy and position of a scattered gamma-ray g y 1photon : reconstruct completely energy & direction low background images Improvement of micro TPC Improvement of micro-TPC 7 th International Conference on Position Sensitive Detectors
μ –PIC(Micro Pixel Chamber) & micro & micro - TPC TPC 2-dimensional imaging 400 μ m gaseous detector d t t (pitch 400 μ m, size 10cm × 10cm) larger one: Takada’s poster larger one: Takada s poster 10cm Max gas gain ～ 15000 Stable operation @gas gain @gas gain ~ 6000 6000 position resolution ~ 120 μ m ~ 120 μ m Electric micro -TPC field Time Projection Time Projection electron 8cm Chamber based on μ -PIC proton 7 th International Conference on Position Sensitive Detectors
For MIP (Minimum Ionizing Particle) detection… Compton camera · · · · · detection of recoil electron by micro-TPC Recoil electron d E /d x ～ 2 ~ 3 × MIP µ-PIC stable operation µ p @ gas gain 6,000 Stable gas gain > 2 × 10 4 (We haven’t achieved because of discharge) sub amplification device GEM(Gas Electron Multiplier) F.Sauli(1997) Operated @ low gas gain(< 50) 7 th International Conference on Position Sensitive Detectors
GEM + μ -PIC -HV system t 5M Ω Cu drift plane -HV HV (5 μ m) (5 μ m) electron cloud 7.5mm 0.5kV/cm polyimide 10M Ω (50 m) (50 μ m) GEM 5mm 2kV/cm 10M Ω μ -PIC GEM installed -HV just above μ -PIC Standard GEM design 70 μ m Mask developed by Hamagaki Lab. 140 μ m 140 μ m @ CNS Univ of Tokyo @ CNS Univ. of Tokyo Plasma etching method @Fuchigami Micro Co Ltd @Fuchigami Micro Co., Ltd. Holes with cylindrical shape 7 th International Conference on Position Sensitive Detectors CNS University of Tokyo
gas gain spectrum Total Gain Total Gain 10 5 GEM Gain requirement requirement 10 4 10 4 s gain Ar 90% C 2 H 6 10% 55 Fe unt with gas flowing with gas flowing gas escape peak(Ar) cou 4 4 6 6 E Energy[keV] [k V] GEM Voltage[V] 20%(FWHM) @ 5.9keV gain 1.3 × 10 4 (1.6cm 2 ) 10 4 (1 6 i 1 3 2 ) μ -PIC gain fixed 2.6 × 10 3 Total Max Gain ～ 10 5 GEM Max Gain ～ 300 7 th International Conference on Position Sensitive Detectors enough to detect tracks of MIPs ！
Positive ion feedback Fractional ion current I D /I A I : the ion current I D : the ion current ck Feedbac on the drift plane I A : the electron current A ional Ion on anodes of µ-PIC the dependence of the fractional ion the dependence of the fractional ion Fracti current on the gain of the GEM Ion feedback less than 10% @ gas gain > 10 GEM gas gain without GEM 30% without GEM 30% total 10% µ-PIC 30% × GEM 30% GEM suppresses the positive ion feedback in a drift region Potential of µ-PIC + GEM system for high-rate condition operation 7 th International Conference on Position Sensitive Detectors
A GEM + µ-PIC TPC -muon track- µ µ-PIC plastic scintillator Ar 90% Ar 90% e - coincidence for C 2 H 6 10% muon trigger e - 0cm drift plane drift plane @ @ total gas gain of 2 × 10 4 l i f 4 10 e - Landau Typical event GEM Distribution 0.2cm Cosmic µ Cosmic µ 8cm 2.5kV/cm 0.4kV/cm track efficiency (hit point > 3) / (trigger) 97% ( p ) ( gg ) dE/dx 7 th International Conference on Position Sensitive Detectors
Position resolution Difference between hit points and tracks obtained from fitting and tracks obtained from fitting 2-dimensional Gauss distribution (the position resolution in the direction of a track is unknown) 0.05 0.05 residual[cm] residual[cm] σ ~ 370µm transverse diffusion 460µm Z-pitch (DAQ clock) ~ 400µm reasonable reasonable 7 th International Conference on Position Sensitive Detectors
Summary & Future Works µ-PIC + GEM PIC GEM stable gas gain of 2 × 10 4 , ion feedback < 10% µ-PIC + GEM TPC 30cm μ -PIC Fine tracks of MIPs were obtained. Fine tracks of MIPs were obtained. track efficiency 97% 30cm position resolution 370µm position resolution 370µm Future Works µ-PIC & GEM with a larger detection area 30cmGEM about 30cm × 30cm(takada’s poster) φ 70 μ m pitch 140 μ m 28cm standard standard design 7 th International Conference on Position Sensitive Detectors 23cm
Performance of μ –PIC (Mi (Micro Pixel Chamber) Pi l Ch b ) 2-dimensional imaging gaseous detector anode 256 × cathode 256 ~ 65000pixels 400 μ m Max gas gain ～ 15000 g g 10cm St bl Stable operation for 1000h ti f 1000h (gas gain ~ 6000) Energy Resolution Energy Resolution 30%(FWHM)@5.9keV(100cm 2 ) ) position resolution p ~ 120 μ m 7 th International Conference on Position Sensitive Detectors
Performance of μ –PIC μ - uniformity - σ ~ 7% 7 th International Conference on Position Sensitive Detectors
μ -TPC ( Time Projection Chamber based on μ -PIC) ( Time Projection Chamber based on μ PIC) 10cm × 10cm μ -PIC Electric field Electron cloud 2-D hit position pos o (Analog & digital) 100MHz encoder time drift distance 3-D tracking electron Electric field field proton t 8cm Applications Compton camera (recoil electron) (recoil electron) Dark Matter search 7 th International Conference on Position Sensitive Detectors
• DAQ system DAQ system Encoder μ -TPC TPC ASD 512ch digital 512ch 32bit summed analog VME (8ch) Memory Board Memory Board VME FADC 100MH 8 h 100MHz 8ch 7 th International Conference on Position Sensitive Detectors
GEM GEM Mask by Hamagaki Lab. @ CNS Univ. of Tokyo Plasma etching method @Fuchigami Micro Co., Ltd. Holes with cylindrical shape CERN : holes with a double-conical shape p CNS-GEM 7 th International Conference on Position Sensitive Detectors
Setup How to glue a GEM -HV drift plane drift plane -HV 5M Ω weight 10M Ω 10M Ω 7.5mm 0.5kV/cm 7 5 0 5kV/ GEM GEM G10 frame 5mm 2kV/cm GEM GEM 10M Ω 10M Ω μ -PIC Glued with -HV epoxy(Araldite) p y( ) aging I d In dry nitrogen gas it Δ V GEM ～ 500V 7 th International Conference on Position Sensitive Detectors
Dependence of total gain on p g induction field Δ V GEM = 250V(gain 10) E D = 0.5kV/cm as gain plateau wasn’t observed p ateau was t obse ved ctive ga the system unstable @ gas gain of ~ 10 5 @ gas gain of ~ 10 Effec Induction Field[kV/cm] 7 th International Conference on Position Sensitive Detectors
Long-term gas gain stability g g g y µ-PIC 6% for 70h 120h gas gain g 70 70 0 0 Time[h] Ti [h] Th The gain increased 50% i i d 50% for 120h 7 th International Conference on Position Sensitive Detectors Hamagaki, CNS Univ. of Tokyo
Performance of micro-TPC - uniformity - 0 1 0.1 0 7 th International Conference on Position Sensitive Detectors
Performance of Hybrid micro-TPC - gamma – ray - gamma ray micro -TPC energy micro TPC energy μ TPC μ TPC mumber of sampling TPC TPC mumber of sampling b b f f li li 13%`20keV(FWHM) Points for one electron track Points for one electron track X-ray from Cu ray from Cu electrode in μ PIC electrode in PIC 7 th International Conference on Position Sensitive Detectors
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