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Dark Matter Search with μTPC （ powerd by μPIC ）

Dark Matter Search with μTPC （ powerd by μPIC ）. Micro Pattern Gas Detector 研究会　 2004 年 12 月 3 日　京都大学 関谷洋之 京都大学. μTPC でとらえられるもの. 電子、　ミューオン Heavy Charged Particle. Neutral Particle. フォトン　 X 線　ガンマ線　　　 electron recoil. Neutron proton (nuclear) recoil. Neutrino electron recoil.

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Dark Matter Search with μTPC （ powerd by μPIC ）

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  1. Dark Matter Search with μTPC（powerd by μPIC） Micro Pattern Gas Detector 研究会　 2004年12月3日　京都大学 関谷洋之 京都大学

  2. μTPCでとらえられるもの • 電子、　ミューオン • Heavy Charged Particle Neutral Particle • フォトン　X線　ガンマ線　　　electron recoil • Neutronproton (nuclear) recoil • Neutrinoelectron recoil • Neutralinonuclear recoil ここでは、暗黒物質　neutralino についてのお話をします。

  3. 暗黒物質 • 2003年　WMAP衛星 宇宙背景放射の ゆらぎの測定 NASA/WMAP Science Team 暗黒物質（CDM）の量は分かったが その分布や何であるのかは依然、謎． 有力候補：SUSYに予言されるneutralino の直接検出を目指した実験

  4. 直接検出？ 京都での今日の風向き 暗黒物質の風 １８：１０ １２：００ 太陽 DARK HALO (Maxwell 分布) Ｖ０＝220km/s ０：００ 暗黒物質（ニュートラリーノ）の直接検出実験 通常の物質と弾性散乱(相互作用)することを利用 　　　地上の検出器中の原子核の反跳を観測する 銀河ハロー中の地球の動きによる“風”暗黒物質のシグナル 白鳥座の方向 232 km/s

  5. μTPCによる方法 散乱された暗黒物質 VＥ γ 暗黒物質の風 反跳原子核 Drift plane WIMP WIND N N μ-TPC 反跳方向に現れる統計的 なシグナルをとらえる N CF4ガスを利用 for SD interactiong DM CF4(Eth=40keV) MWIMP=50GeV μPICの性能 • Track length threshold: 3 mm • dE/dx threshold: 10 keV/cm cos g 低圧力での動作研究が必要

  6. 低圧での動作試験 Gas vessel 60cm m-TPC • 10x10x10cm3 μTPC 　ガス容器中 • まずはAr+C2H6中での5.9keVX線　 Gas gain variation 1atm 0.5atm 0.2atm Ar+C2H6 (9:1) Time [hour] • 0.1 atmまでの低圧でシグナルを確認 • ガスゲインの低下はOut-Gasの影響

  7. 中性子による原子核反跳 g YAP (trigger) 252Cf g low pressure gas n m-TPC p or C • Experimental setup Ar+C2H6 gas ２００keV 反跳に対する 期待される range (SRIM2003)

  8. 得られた飛跡１ • 水素反跳 • 3D tracking • Bragg curves n 計算したrange 測定したrange 測定したchargeから 　　　　　　　のエネルギー が一致している Bragg curves

  9. 得られた飛跡２ • 炭素反跳 n 350keV = 8mm (SRIM) Bragg curve

  10. CF4での基礎動作試験 Gas gain Drift velocities of electrons 104 CF4 100% Gas gain CF4 100% (1atm) Ar+C2H6 (1atm) 0.25 atm 0.5 atm 1 atm Source: 55Fe (5.9keV) 103 600 700 800 Electric field [kV/cm] Anode voltage [V] • gas gain>7000 @ 0.25 atmで　安定動作 • C,F反跳飛跡取得の実験準備中です。

  11. 実験計画 SD 3s detection sensitivities sWIMP-p [pb] γ WIMP WIND hatched：WIMPpainted：neutron BG MWIMP [GeV] F cos g 大型化が必要　　高田 R&D with 800cm3 • n BG measurement @ Kamioka • 1m3m-TPC • g-ray BG rejection • Electron diffusion • Low pressure operation 1m3 ×30m-TPC 2004 2005+ 201?

  12. WIMP-wind Detection with an AdvancedGaseous Tracking Device DARK2004 6 October, 2004 Texas A&M University, College Station, TX, USA Atsushi Takeda T. Tanimori, H. Kubo, K. Miuchi, T. Nagayoshi, H. Sekiya, R. Orito, A. Takada, Y. Okada, H. Nishimura, K. Hattori Kyoto University

  13. Table of Contents • Direction sensitive WIMP search • m-TPC: 3-D tracking device • WIMP-wind detection with m-TPC • Study with 10cm-size detector as a WIMP-wind detector • Summary

  14. 1. Direction sensitive WIMP search Detecting WIMP-wind distribution with a gaseous tracking device Drift plane WIMP WIND μ-TPC N N N WIMP WIND CF4(Eth=40keV), MWIMP=50GeV γ F Very large asymmetry cos g • WIMP-wind is blowingfrom the direction of the Solar motion Detecting only energy spectra with a conventional detector [counts/keV/day/kg] Only a few % rate difference Recoil energy [keV]

  15. 2. m-TPC: advanced gaseous device Drift plane electron cloud Cathode 400m Anode 100m 50m with a micro pixel chamber (m-PIC) readout m-PIC • 2-D imaging detector • 400mm pitch electrodes • simple structure • stable operation • large area (PCB technology) μ-TPC: μ-PIC + TPC (x, y) (drift time) 3D tracking

  16. Anode Cathode 10cm 10cm 30cm 30cm m-PIC, Micro Pixel Chamber • Practical size (10cx10cm2) m-PICs are working well • Now, large size (30x30cm2) m-PIC is being manufactured

  17. Performance of the 10x10cm2m-PIC (1/2) • High gas gain max: 16000 • Good gain uniformity ~4.5% (s) • Good spatial resolution ~120mm (s) • Stable operation>1000 hours (gas gain ~6000) Gain uniformity 10cm NIM A 525 (2004) 20 Gas gain 104 Ar:C2H6 = 9:1 Ar:C2H6 = 8:2 103 Anode [cm] 440 520 600 Cathode [cm] Anode voltage [V]

  18. 0.5mm slits X-ray image 55Fe spectrum @ 10cmx10cm MnKa 5.9keV FWHM 30% Xe:C2 H6 = 7:3 Ar-esc Knife edge test Counts position resolution σ=120mm ADC [ch] 1mm Length along the edge [mm] Performance of the 10x10cm2m-PIC (2/2)

  19. 10cm E=500V/cm 10cm 0.2mm Cu wires 10cm Prototype m-TPC • 10×10×10cm3 detection volume

  20. VME Memory Board 256ch (anode) 256ch (cathode) VME FADC 100MHz 8ch DAQ system Encoder board • 5 FPGAs • take anode-cathodecoincidence @ 50MHz m-TPC 512ch LVDS digital 256ch (anode) 256ch (cathode) 32bit 512ch 3-D tracking ASD board • Amplifier-Shaper-Discriminator (ASD) chip summed analog (8ch) Bragg curves

  21. Performance of the m-TPC (1/2) • 3-D tracks obtained with Ar+C2H6 of 1atm electron tracks Proton tracks 252Cf n

  22. Performance of the m-TPC (2/2) • Gamma-ray rejection χ2/d.o.f NIM A517 (2004) 219 30 30 22Na (γ) 252Cf (n+γ) (511keV g) 20 20 χ2/d.o.f c2/d.o.f. c2/d.o.f. 10 10 0 0 100 200 300 400 500 100 200 300 400 500 dE/dX [keV/cm] dE/dX [keV/cm] nucleus event large dE/dx Nucleus events have straight track

  23. 3. WIMP-wind detection with m-TPC • Comparing to the other experiment Our m-TPC DRIFT project • Fine pitch (400mm) • 3-D tracking • Mechanically stable • Mass production (PCB technique) • First detector with sensitivity to the directions of nuclear recoils • MWPC with 2mm pitch • 2-D tracking only wireless, no 3-D geometry

  24. Detection sensitivities as of shown in PLB 578 (2004) 241 • Experimental parameters used for the calculation Target gas: CF4 for Spin-dependent (SD) interaction • Track length threshold: 3 mm • dE/dx threshold: 10 keV/cm • g-ray discrimination ~100% • Bragg curves are detected Need to study low-pressure m-TPC

  25. Expected WIMP signal • CF4 20Torr • Fast neutrons are the only BG source • 50cm water shield • Forward/Backward asymmetry @Kamioka γ WIMP WIND hatched：WIMPpainted：neutron BG F cos g

  26. Detection sensitivities Spin-dependent sWIMP-p [pb] MWIMP [GeV] • Estimated 3s detection sensitivities at Kamioka Observatory for SD interaction

  27. 4. Study with 10cm-size detectoras a WIMP-wind detector • Operation with low-pressure gas • 3-D tracking with low-pressure Ar+C2H6 gas • Operation with CF4 gas including 19F whose large cross section for SD interaction • Required operation pressure: 0.05 ~ 0.2 atm • Confirm tracking capabilities under low-pressure using a standard gas • Properties of CF4 gas

  28. Operation with low-pressure gas • 10x10x10cm3m-TPC in the gas vessel • Gas vessel is available for 30x30 cm2 detector Gas vessel Gas gain variation 60cm m-TPC 1atm 0.5atm 0.2atm Ar+C2H6 (9:1) Time [hour] • Signals were observed down to 0.1 atm • Out-gas should be suppressed

  29. g YAP (trigger) 252Cf g low pressure gas n m-TPC p or C 3-D tracking with low-pressure Ar+C2H6 gas • Experimental setup Calculated range of nuclei whose energy of 200 keV (SRIM2003)

  30. Obtained 3-D tracks (1/2) • tracks of recoil protons • 3D tracking • Bragg curves n range v.s. charge roughly agrees with SRIM Bragg curves

  31. Obtained 3-D tracks (2/2) • Carbon candidate n 350keV = 8mm (SRIM) Bragg curve

  32. Operation with CF4 gas Gas gain Drift velocities of electrons 104 CF4 100% Gas gain CF4 100% (1atm) Ar+C2H6 (1atm) 0.25 atm 0.5 atm 1 atm Source: 55Fe (5.9keV) 103 600 700 800 Electric field [kV/cm] Anode voltage [V] • Stable operation with gas gain>7000 @ 0.25 atm • Confirmed drift velocities of electrons in CF4 gas are fast

  33. 4. Summary • WIMP-wind detection • m-PIC has a fine pitch (400 mm) • Study with 10cm-size detector • Low pressure operation (0.2 atm) • Proton and carbon 3-D tracks • Properties of CF4 gas • 30cm-size TPC will be ready at the end of 2004

  34. g Drift [cm] n Anode [cm] Cathode [cm] Direction sensitive detector under development • Organic scintillators - Minowa group (Tokyo) • Gas detectors - DRIFT （UK） - m-TPC （Kyoto） DRIFT project Our m-TPC UKDMC, Occidental College, Temple Univ., LLNL • m-PIC with 400mm pitch • 3-D tracking • Mechanically stable • First detector with sensitivity to thedirections of nuclear recoils • MWPC with 2mm pitch • 2-D tracking only wireless, no 3-D geometry • Mass production

  35. “Detection” by Forward/Backward 3σasymmetry SI 3s detection sensitivities SD 3s detection sensitivities sWIMP-p [pb] sWIMP-n [pb] MWIMP [GeV] MWIMP [GeV] Time schedule R&D with 800cm3m-TPC • n BG measurement @ Kamioka • 1m3m-TPC • g-ray BG rejection • Electron diffusion • Low pressure operation 1m3 ×30m-TPC 2004 2005+ 201?

  36. track direction is important F/B ~ 5 track+direction track only F/B ~ 1.3

  37. Expected rate • threshold: 40keV • WIMP mass: 50 GeV for F, Ar100GeV for Xe • WIMP-ｐ cross section : 0.1 pb for SD10-6 pb for SI

  38. S/N calculation • threshold: 40keV • WIMP mass: 50 GeV for F, Ar100GeV for Xe • WIMP-ｐ cross section : 0.1 pb for SD10-6 pb for SI

  39. Expected 95 % C.L. sensitivities Spin-Independent Spin-Dependent Xe 10 m3, 1 year noshield CF4 10 m3, 1 year noshield CF4 30 m3, 3 years 35cm water shield Xe 30 m3, 3 years 35cm water shield

  40. Threshold dependency of F/B • gas: CF4 • WIMP-p: 0.1 pb spectrum • forward/backward • increases with the • threshold energy

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