Current status of the thick-GEM TPC for the J-PARC E15 experiment Fuminori Sakuma (RIKEN) Tum-Riken Kick-Off Meeting @ TUM, May 10-11, 2010. 1
Contents Introduction TGEM-TPC for the J-PARC E15 exp. Thick GEM (TGEM) goal: gain 〜 10 4 with stable operation in P10 @ NTP Results of TGEMs in P10 @ NTP • Cu-electrode TGEMs • C-electrode TGEMs • C/Cu-electrode Hybrid TGEMs Summary 2
J-PARC E15 Experiment search for K-pp bound state using 3 He(K - ,n) reaction neutron 3 He K - pp K - Formation cluster Decay Mode to decay charged particles Λ p exclusive measurement by π - Missing mass spectroscopy and I nvariant mass reconstruction p at J-PAR at ARC 3
J-PARC E15 Setup Sweeping Beam Line Magnet Spectrometer Beam trajectory K1.8BR CDS & target Beam Line Neutron Neutron Counter ToF Wall p Beam Sweeping n Magnet mass resolution for K-pp π − Cylindrical invariant mass p σ = 19MeV/c 2 ( σ CDC = 250 µ m) Detector 1GeV/c missing mass (for 1.3GeV/c neutron) System σ = 9.2MeV/c 2 ( σ ToF = 150ps) 4 K- beam
measurement of mesonic decay-mode of K - pp important to measure not only non-mesonic decay mode but also mesonic decay mode mesonic mode is suppressed! Thick-GEM TPC improves z-resolution
TGEM-TPC for the J-PARC E15 exp. 6
TGEM-TPC for the J-PARC E15 exp. TGEM-TPC is located at the center of Cylindrical Detector System •located between CDC and target-chamber •cover the CDC acceptance of AUVA •minimum materials in the acceptance •1mm spatial resolution in the z-direction TGEM 〜 2m TPC TGEM Cylindrical Detector System TGEM-TPC filled with P10 gas at atmospheric pressure 7
completed TGEM-TPC R/O pad size 4mm × 20mm HV connector 4mm R/O # of pad = 4 × 4 × 9 = 144 Gas connector TGEM field strip •double sided 8mm •FPC 2 cm •8mm strip •10mm pitch 28 cm 10mm non-necessity of support-structure!
making of Field Cages soldering resisters(1M Ω ) Large FPC board sticking support frames on the FPC rolling up the FPC Inner and Outer field cages completed uniting the two cages 9
HV connector preamp attachment (test) HV & Readout (LEMO, max. 15kV) readout pad readout with TGEM TGEM close up view of double-TGEM installation to reduce detector capacitance, one side of TGEM is 10 divided into 3 parts
Readout Electronics is the same as that of CDC preamp cards and cables are attached LVDS ECL converters TDC’s in the counting room at the exp. hall •Chip : CXA3183Q (SONY , low noize ASD IC, τ =16nsec) τ =80nsec ECL LVDS •Output : LVDS differential 8m 60m •Gain : 0.8V/pC at preamp •4x4=16ch cables cables We measure only time info. with the TPC! 11
gas limit of HV module : 15kV maximum drift-field voltage : GEM HV : 4kV ~350V/cm drift length : 30cm We choose P10 (Ar/CH 4 =90/10) for the TGEM-TPC gas E = 150V/cm expected resolution C dl = 0.34mm, C dt = 0.60mm σ 0l = 0.5mm ⋅ 2 C z σ = σ + 2 2 d σ 0t = 0.2mm x 0 N N eff = 38.7*0.4(cm) = 15.5 eff σ x 0.9 : total resolution transverse σ 0 0.8 : resolution w/o diffusion 0.7 C d : diffusion constant longitudinal resolution(mm) 0.6 z : drift distance 0.5 N eff : effective number of electrons 0.4 σ l σ t z D l D t 0.3 (c (cm) (mm) mm) (mm) mm) (mm) mm) (mm) mm) longitudinal 0 0.00 0.00 0.50 0.20 φ -direction resolution is limited 0.2 10 1.09 1.89 0.57 0.52 transverse 0.1 20 1.54 2.67 0.63 0.71 by pad size, e.g., 30 1.88 3.27 0.69 0.85 0.0 20.0/sqrt(12) = 5.8mm 0 5 10 15 20 25 30 35 So we use only z-direction info. z(cm) 12
Thick GEM (TGEM) goal: gain 〜 10 4 with stable operation 13
What is TGEM ? Thick-GEM is … cost-effectively fabricated from double-clad G10 plates, using standard printed circuit board (PCB) techniques holes are mechanically drilled (and, if necessary, the hole’s rim is chemically etched to prevent discharges) a robust, simple to manufacture, high-gain gaseous electron multiplier easy to operate and feasible to cover large areas, compared to the standard foil GEM TGEM cross-section and drift line avalanche TGEM@RIKEN avalanche Drilled hole Rim 100 µ m 300 µ m thickness: 400µ m ∆ V GEM ∼ 1kV Garfield Simulation 14
TGEM prototypes goal gain 〜 10 4 @ P10, NTP (double TGEMs) stabile operation for a month, with gain fluctuation within ~a few ten % for a month & a few % for a day many groups have reported TGEMs work successfully, but actually it’s NOT so easy to operate TGEM with high gain stably! they use small TGEMs, e.g. ~3x3cm 2 most of them don’t discuss stability of TGEM We have studied basic TGEM behavior and performance. 15
TGEM prototypes @ RIKEN produced by REPIC corp. and TOUKAI DENSHI KOUGYOU corp. ss[ µ m] r[ µ m] Rim[ µ m] Thickn kness[ Hol Hole-diame meter[ m] No. No. Electrod rode Ins nsul ulator 1 Cu Cu FR4/U 4/UV 200 200 300 300 50 50 ×2 2 Cu Cu FR4/U 4/UV 200 200 500 500 - ×2 3 Cu Cu FR4/U 4/UV 400 400 300 300 - ×5 4 Cu Cu FR4/U 4/UV 400 400 300 300 30 30 ×2 5 Cu Cu FR4/U 4/UV 400 400 300 300 50 50 ×2 6 Cu Cu FR4 FR 400 400 300 300 100 100 ×2 7 Cu Cu FR4/U 4/UV 400 400 500 500 - ×2 8 C FR4 FR 400 400 300 300 - ×4 9 C FR4/U 4/UV 400 400 300 300 - ×7 10 10 C G10 400 400 300 300 - ×2 11 11 C CEM EM3 400 400 300 300 - ×2 12 12 C FR4 FR 600 600 300 300 - ×2 13 13 C/ C/Cu Cu FR4/U 4/UV 400 400 300 300 - ×4 size : 10cm x 10cm Tota tal 40 16
many TGEM prototypes 17
Test bench setup test chamber Double GEM setup 55 Fe drift mesh X-ray E drift 11mm TGEM 1 e - (150V/cm) ΔV GEM 2mm E trns TGEM 2 ΔV GEM 2mm E ind R/O pad CS preamp readout pad DC 1M 72Hz low-pass 20M mesh doub uble TGE TGEMs 11mm 2200p 1M 20M GEM1 400um 2M Ga Gas : : P10 a 10 at 20M GEM1 2mm 1M 1a 1atm, no normal t tem emper eratur ure 20M GEM2 400um 2M 20M GEM2 HV V div ivid ider w wit ith h res esis istive cha chain in 2mm 1M R/O Ratio of ∆ V GEM /E trns /E ind is const. 18
Results of TGEMs 19
Cu-electrode TGEM ss[ µ m] Hol r[ µ m] m] Rim[ µ m] ulator Thickn kness[ Hole-diame meter[ No. No. Electrod rode Ins nsul Max g gain 1 Cu Cu FR4/U 4/UV 200 200 300 300 50 50 〜 10 10 3 2 Cu Cu FR4/U 4/UV 200 200 500 500 - - 3 Cu Cu FR4/U 4/UV 400 400 300 300 - 〜 10 10 4 4 Cu Cu FR4/U 4/UV 400 400 300 300 30 30 ov over r 2×10 10 4 5 Cu Cu FR4/U 4/UV 400 400 300 300 50 50 ov over r 2×10 10 4 6 Cu Cu FR FR4 400 400 300 300 100 100 ov over r 2×10 10 4 7 Cu Cu FR4/U 4/UV 400 400 500 500 - 〜 10 10 3 Rim of 50,100μm : Weizmann method (drilling + masked etching) Rim of 30μm : CERN method (drilling + resist etching) w/o Rim (#3) : w/ hydrogen peroxide - sulfuric acid etching TGEMs with thickness of 400μm and hole diameter of 300μm achieve maximum gain of 10 4 20
dependence on rim size E drift =150V/cm the limits of gain around 10 5 is caused ∆ V GEM (V) : : E induct (V/cm) E trans (V/cm) by reather limit (source = 55 Fe). 1 : : 2.5 7.5 1.0E+05 goal 1.0E+04 effective gain 1.0E+03 Cu Rim 100 μ m 1.0E+02 Cu Rim 50 μ m Cu Rim 30 μ m 1.0E+01 Cu no Rim 1.0E+00 800 900 1000 1100 1200 ΔV GEM [V] TGEM with larger rims requires higher voltage, but enables higher gain 21
gain and resolution stability (24h) 100 µ m 30 µ m gain resolution( σ ) [%] 50 µ m corrected relative gain 〜 2.5 × 10 4 No Rim 100 µ m 30 µ m 50 µ m gain energy resolution@5.9keV(σ) No Rim TGEMs with rims ( , , ) are NOT so stable TGEM without rims ( ) is stable initial drop of gain is caused by charge-up (polarization?) of the insulator? instability of TGEMs with rims is caused by charge-up of the insulator not metalized. mismatch of the center of the etched and drilled holes and incomplete round-shape of rims cause the instability. 22
long term stability (30 µ m rims TGEM, 10days) 2 2 P/T corrected data relative gain relative gain raw data gain=2.5 × 10 4 1 1 gain~2.5 × 10 4 gain=1.0 × 10 4 0 0 0 10days 0 10days ∆ V GEM is turned up by hand resolution( σ ) [%] 40 20 0 0 10days TGEM with 30 µ m rims can be operated with gain of more than 10 4 for the long term @ P10, NTP gain stability is within ~50%/week & ~10%/day 23
C-electrode TGEM To avoid the effects of rims, we are developing a new resistive-electrode TGEM (RETGEM ) which has electrodes coated with graphite paint . RETGEMs have an advantage of being fully spark-protected. ss[ µ m] Hol r[ µ m] m] Rim[ µ m] No. No. Electrod rode Ins nsul ulator Thickn kness[ Hole-diame meter[ Max g gain 8 C FR FR4 400 400 300 300 - over ov r 2×10 10 4 9 C FR4/U 4/UV 400 400 300 300 - - 10 10 C G10 400 400 300 300 - 〜 10 10 3 11 11 C CEM EM3 400 400 300 300 - ov over r 2×10 10 4 12 12 C FR FR4 600 600 300 300 - 〜 10 10 2 24
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