NEWAGE Hironobu Nishimura （ Kyoto University) K. Miuchi T. Tanimori, H. Kubo, S. Kabuki, A. Takada, K. Hattori, K. Ueno, S. Kurosawa, T.Ida, S.Iwaki A. Takeda (ICRR), H. Sekiya (ICRR) (New generation WIMP search with an advanced gaseous tracker experiment) Direction sensitive dark matter search TAUP2007, Sendai Sep

OUTLINE Direction sensitive DM search ３ D-Track Detector (Micro-TPC) Surface run result NEWAGE first mine SUMMARY

１. Direction sensitive DM search “WIMP-wind” detection 220km/s cos γ WIMP WIND γ F F WIMP

Our Plan of direction sensitive DM serch Gas target + 3D tracking device (next section) Tracking recoil nucleus Gamma rejection by dE/dx Goal: Detect the WIMP-wind （ 2010~ ） underground ・ low pressure ( CF bar ) large volume （ 1m 3 × N ） CURRENT: CF bar 23×27×30 cm 3 Sensitivity (Spin Dependent)

2Detector micro-TPC (micro time projection chamber) Feb. 20, 2007 APPEAL07 Position Encoder  PIC (×5000) GEM(×10) TPC Particle tracks e NIM A 576 (2007) 43 K.Miuchi et.al 40cm TPC X readout (768ch) Y readout (768ch) FAGA position encoder (1536ch)

Gas amplify and read out Drift Field ~200V/cm Gas volume DRIFT length 31cm CF 4 0.2bar gas, sealed 23×28×31cm 3 e - cloud 31cm 140μm φ70μm GEM: Gas gain 2 30cm μPIC μ-PIC : Gas gain μ m pitch 589,824 pixels 400 μ m

Example Gas CF 4 0.2bar Alpha-Particle Event Nhit=18 Energy=6.5MeV Length=10.2cm X-Z X-Y Z-Y Analog waveform TPC performance tracking 3D spatial resolution ~ 800 μ m cf. F(100keV) run 800 μ m Track 2D + time = 3D Energy Analog waveform

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) 0.2bar Protons have longer tracks n -> p forward scattering are seen (this is what we want to do with WIMP -> F scatterings) TPC performance direction Horizon γ γ

TPC performance gamma-ray rejection gamma-rays from 137 Cs gamma efficiency ＜ 2e-4 （ statistics limited ） >100keV 137Cs  neutron （ BG ） With 137Cs Without （ BG run ） Spectrum subtracted keV 0

3 Surface Run K.Miuchi et. al. To appear in PLB Preprint arXiv: Nov.1 st ~ Nov.27 th exposure 0.15 kg university (N35.03 E ） BG spectrum E>100keV L<1cm

3 Surface Run SKYMAP Direction of WIMP wind Cosγ distribution dru GeV/c 2 |Cosγ|

KAMIOKA LAB-B 2006/12/12 KAMIOKA Lab-B 2007/1/19 4 Underground In Kamioka mine 2700m w.e depth neutron (v.s surface) No shield Stable Operation Background Study TOKYO Kamioka KYOTO Super Kamiokande Sendai

First operation 2007 Jan. Feb. Mar. Apr. May Jun. Jul. Aug. cal Install Comissioning run BG run 1 BG run 2 GEM trouble. lost Effective Area Gas replace Gas replace cal Replace GEM BG run exposure [kg∙days] cal BG run 2007 Mar 6 th ~Aug 6 th 0.23 kg∙days 8 calibrations run with 252 Cf. 2 replaces of gas Fiducial mass 1.9g

Spectrum (preliminary) BGrun1 + BGrun2 0.23kg∙days Length 100keV BG decrease 40% of blue ： Surface Run red ： Kamioka first (preliminary) cts/kg/kev/days

Background Origin alpha or heavy particle (Inside Chamber) 222 Rn in U chain: U, Th in drift plane and GEM DAY α (5.5, 6.0, 7.6 MeV) BG spectrum ( fiducial cut only 0~10MeV)

SUMMARY μTPC (3D imaging device) Gas: CF4: 0.2 bar sub mm Result of Surface run K.Miuchi et. al. to appear in PLB Preprint arXiv: underground run started Total exposure 0.23 kgday up to Aug.2007 Event rate is 40% of surface run Now background study Future work Reduce Rn, U, Th in detector Larger Detector, low pressure Low background run

Thank you !!

TPC performance CF 4 0.2atm 24×27×30cm 3 Energy resolution 5~8 MeV Position resolution 800 μ m (rms) angular resolution ~15° (HWHM)

Fiducial cut X Y Reject Cannot reject reject by x-y projection

Energy calibration 10 B ( thickness 0.6μm ) 10 B(n,a) 7 Li reaction (Q=2.70MeV 1.8MeV for  ) XY image keV spectrum Energy vs length keV   Li 2000 spectrum (GEANT4 ）

222 Rn emanation and alpha from drift plane U 232 Rn α α Drift Plane Fiducial area Increase of 6MeV With decay constant of Rn (3.8days) U Chamber

Stability(BGrun2) Gas gain &DAQ rate: Slow decrease 10%~20% / month →correct by analysis →recover by replacing new gas 5/15 7/1 8/2 Hz DAQ rate Gas gain

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)