H. Nishimura DM search with a TPC （ NEWAGE ） Hironobu Nishimura （ Kyoto University) K. Miuchi T. Tanimori, H. Kubo, S. Kabuki, K. Tsuchiya, A. Takada, Y. Okada, K. Hattori, K. Ueno, S. Kurosawa A. Takeda (ICRR), H. Sekiya (ICRR) Feb. 20, 2007 APPEAL07 (New generation WIMP search with an advanced gaseous tracker experiment)

H. Nishimura OUTLINE Direction sensitive DM search Micro-TPC NEWAGE surface run FUTURE PLANS & SUMMARY Feb. 20, 2007 APPEAL07

H. Nishimura Jan 27, rd MPGD workshop １. Direction sensitive DM search “WIMP-wind” detection The WIMP-wind WIMP V 0 =230 km/s SOLAR SYSTEM 220 km/s PLB 578 (2004) 241

H. Nishimura Jan 27, rd MPGD workshop WHY “Direction-sensitive” ? Large mass for exclusion （ and indication ） BUT Annual modulation is not enough… Direction-sensitive for detection WIMP WIND γ F F Annual modulation direction Asymmetry

H. Nishimura Sensitivities Goal: Detect the WIMP-wind （ 2010~ ） underground ・ low pressure ( CF bar ) ・ large volume （ 1m 3 × N ） CURRENT: surface ・ CF bar ・ 30cm cube Feb. 20, 2007 APPEAL07 sensitivity

H. Nishimura 2 micro-TPC (3D tracking device) Feb. 20, 2007 APPEAL07 Jan 27, rd MPGD workshop Position Encoder  PIC (×5000) GEM(×10) TPC Particle tracks e Preprints: physics/ K.Miuchi et.al 40cm TPC X readout （ 768ch ） Y readout （ 768ch ） FAGA position encoder （ 1536ch ） 23×28×31cm 3

H. Nishimura  -PIC (gas gain 5000) Pixel-type gas multiplier pixels 400 μ m pitch readout Feb. 20, 2007 APPEAL07 2D imaging device 28cm 23cm 30cm μPIC (Toshiba) Large area GEM (scienergy) Takada et. Al. PSD7  PIC GEM TPC 30cm 5mm Particle tracks e GEM (gas gain 10) 140 μ m pitch 70 μ m diameter 400 μm Anode Cathode 140μm φ70μm

H. Nishimura Readout electronics 768 anode cathode Digital (LVDS) signals at ASD (X,Y,T) at the position encoder for tracking Feb. 20, 2007 APPEAL07 31cm gas volume Kubo et. al. IEEE/NSS 2005 TPC system ENCODER ASD for energy + Summed analog signal TPC system Gas volume DRIFT length 31cm CF 4 0.2bar gas, sealed 100MHz, pipeline

H. Nishimura Jan 27, rd MPGD workshop TPC performance ① tracking 400  m digital “HIT” ( for tracking) + summed analog ( for energy) F 500keV 5~6mm in 0.2atm CF 4 F,C tracks n 252 Cf Y X -15cm 15cm -15cm 30cm Z(drift) 0cm X,Y image Z(time) projection Fiducial 24×21.5×31cm 3 (CF4 8.9g) FLAT response trigger Trigger ： z=0 cm 30 Preprints: physics/ K.Miuchi et.al

H. Nishimura 2006 年 11 月 17 日 TPC performance ② stability Drift velocity: fast drop ⇒ slow decrease after 1 day gain, energy resolution ： stable within the systematic error

Jan 27, rd MPGD workshop Recoil direction image 252 Cf （ NE45° zenith35° ） 1 0 Cos   n p CF 4 +C 4 H Cf run Proton tracks n 252 Cf Y X -15cm 15cm -15cm 30cm Z(drift) 0cm CF 4 +C 4 H 10 (9:1) Protons have longer tracks n -> p forward scattering are seen (this is what we want to do with WIMP -> F scatterings) TPC performance ③ direction Horizon

H. Nishimura TPC performance ④ gamma-ray rejection gamma-rays from 137 Cs gamma efficiency ＜ 2e-4 （ statistics limited ） 137Cs  neutron （ BG ） With 137Cs Without （ BG run ） Spectrum subtracted

H. Nishimura Surface run ① 2006 Nov.1 st ~ Nov.27 th exposure 0.15 kg days (=0.0089kg university (N35.03 E ） Energy spectrum （ conventional method ） : consistent with neutron BG Energy spectrum 3 Surface run

H. Nishimura Surface run ② The sky map flat neutron background is seen North sky view seen by C and F nuclei ( keV) DM direction Horizon

Jan 27, rd MPGD workshop Surface run ③ Cosθ distribution consistent with a flat distribution Cosθ 分布 ( keV) DM limit First result of Direction Sensitive!! First step to the NEWAGE WE ARE HERE

H. Nishimura Jan 27, rd MPGD workshop Go underground JUST started KAMIOKA LAB-B 2006/12/12 KAMIOKA LAB-B 2007/1/19 SPring-8 Kyoto Kamioka 4 Next step…

H. Nishimura Jan 27, rd MPGD workshop SUMMARY μTPC ： 30cm cube in operation Gas: CF4: 0.2 bar direction sensitive WIMP-wind detector direction-sensitive method works! On surface Obtain First upper limit !! NEWAGE ： underground run just started

H. Nishimura Feb. 20, 2007 APPEAL07 Gas gains operation gain for MIPs ~50,000 Gain curves Gain map Gain uniformity Maximum / minimum = 2.2 TPC performance (with Ar+C2H6 gas)

Jan 27, rd MPGD workshop Spectra Energy spectra from the whole volume (with energy corrections) 109 Cd linearity Energy resolution 133 Ba 241 Am Ag-K  Cu-K  Cs-K  Cu-K  59.5keV keV 31keV 8keV

Jan 27, rd MPGD workshop Particle Tracking muons Electrons (~100keV) Protons (~2MeV) 30cm Neutrons （ 252Cf ） 511keV  ‘s （ 22Na ） Cosmic ray muons

Jan 27, rd MPGD workshop 3D Spatial resolution Fit muon tracks with straight lines plot the residuals Residual muon tracks data Fitted line data residual Residual (short drift) Residual (long drift) Drift length  -PIC  dependence on drift length r [cm] ｌ [cm]

検出器の 方向依存感度マップ 検出器応答 検出器応答の方向依存性（相対的） 線源を (50cm,0,0) (0,50cm,0) (0,0,50cm) の 3 箇所 （それぞれ 10k 事象）スキャンして測定：ほぼ等方 な反跳を GENERATE

Track length threshold : 3 mm dE/dx threshold : 10 keV/cm with electron/nuclear recoil discrimination ability recoil direction sensitivity (Bragg curves) gasPressure [Torr] Density [g/m 3 ] Xe538 CF Need to study low-pressure μTPC Sensitivity to WIMPs Properties of μTPC Drift plane μ-TPC N N N WIMP WIND WIMP WIND γ F F cos  CF 4 (E th =40keV), M WIMP =50GeV Very large asymmetry

Spin-dependent SI 3  detection sensitivities Sensitivity to WIMPs SD with CF 4 20 torr M WIMP [ GeV ]  WIMP-p [ pb ] SI with Xe 5 torr M WIMP [ GeV ]  WIMP-n [ pb ] “ Detection ” by Forward/Backward 3σasymmetry At Kamioka Observatory (1000 m.w.e) 0.3 m 3 year exposure reach the best sensitivity. 300 m 3 year exposure will test the MSSM prediction.

エネルギー校正 ガラスに蒸着した 10 B ( 厚さ 0.6μm ) ドリフトケージ内部にセット、外から 252Cf の中性子を減速して照射 10B(n,a)7Li 反応 (Q=2.70MeV 1.8MeV for  ) 原子核による校正、低エネルギーへの線形性は別途確認示す必要あり 現状では、校正には 6 時間程度、見せれる絵には 12 時間程度かかっている XY イメー ジ keV スペクトル エネルギー vs 飛跡長 keV   Li 2000 スペクトル (GEANT4 ） 検出器応答

エネルギー分解能 高エネルギー（ 5-8MeV ）では Rn のピークを使ってモニタ 40 ％ FWHM これは検出器固有の数字（ゲインのばらつきが効いてい る） 検出器応答