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NEWAGE

NEWAGE. ( Ne w generation W IMP search with an a dvanced g aseous tracker e xperiment) Direction sensitive dark matter search. TAUP2007, Sendai Sep.12 2007. Hironobu Nishimura （ Kyoto University) K. Miuchi T. Tanimori, H. Kubo, S. Kabuki, A. Takada,

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NEWAGE

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  1. NEWAGE (New generation WIMP search with an advanced gaseous trackerexperiment) Direction sensitive dark matter search TAUP2007, Sendai Sep.12 2007 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)

  2. OUTLINE DirectionsensitiveDMsearch ３D-Track Detector (Micro-TPC) Surface run result NEWAGEfirst run @Kamioka mine SUMMARY

  3. １.DirectionsensitiveDMsearch“WIMP-wind”detection WIMP WIND γ F -1 0 1 cos γ WIMP 220km/s

  4. Sensitivity (Spin Dependent) • 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 ( CF4 0.05 bar ) • large volume （1m3 × N） • CURRENT: • CF4 0.2 bar • 23×27×30 cm3

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

  6. φ70μm 140μm • Gas amplify and read out • Gas volume • DRIFT length 31cm • CF4 0.2bar gas, sealed GEM: Gas gain 2 Drift Field ~200V/cm e- cloud 31cm 30cm μPIC 400μm μ-PIC : Gas gain 2000 400μm pitch 589,824 pixels 23×28×31cm3

  7. TPC performancetracking • Track • 2D + time = 3D • Energy • Analog waveform X-Z • Example • Gas CF4 0.2bar • Alpha-Particle Event • Nhit=18 • Energy=6.5MeV • Length=10.2cm X-Y 3D spatial resolution ~ 800μm cf. F(100keV) run 800μm Z-Y Analog waveform

  8. Proton tracks 30cm • CF4+C4H10(9:1) 0.2bar • Protons have longer tracksn -> p forward scattering are seen (this is what we want to do withWIMP -> F scatterings) 252Cf n Z(drift) • TPC performance direction 15cm 0cm -15cm -15cm 15cm X Y 252Cf（NE45°zenith35°） CF4+C4H10252Cf run n Horizon γ q p 0 γ Recoil directionimage 1 Cos Jan 27, 2007 3rd MPGD workshop

  9. TPC performancegamma-ray rejection • gamma-rays from 137Cs Spectrum With 137Cs Without （BG run） 137Cs g subtracted neutron（BG） 0 0 100 200 300 400keV • gamma efficiency　＜　2e-4　（statistics limited） • >100keV

  10. 3 Surface Run • 2006 Nov.1st ~ Nov.27th • exposure 0.15 kg days • @Kyoto university (N35.03E135.783） BG spectrum E>100keV L<1cm K.Miuchi et. al. To appear in PLB Preprint arXiv:0708.2529

  11. 3 Surface Run Cosγ distribution dru Direction of WIMP wind 0 1 |Cosγ| SKYMAP 101 102 103 GeV/c2

  12. 4 Underground run @Kamioka KAMIOKA Lab-B 2007/1/19 • In Kamioka mine • 2700m w.e depth • 10-3 neutron (v.s surface) • No shield Sendai • Stable Operation • Background Study Kamioka TOKYO KYOTO KAMIOKA LAB-B2006/12/12 Super Kamiokande

  13. First operation report @Kamioka GEM trouble. lost Effective Area Replace GEM Gas replace Install Gas replace 2007 Jan. Feb. Mar. Apr. May Jun. Jul. Aug. BG run 2 Comissioning run BG run 1 BG run exposure [kg∙days] 0.08 0.15 cal cal cal cal cal cal cal cal BG run 2007 Mar 6th ~Aug 6th 0.23 kg∙days 8 calibrations run with 252Cf. 2 replaces of gas Fiducial mass 1.9g

  14. Spectrum (preliminary) • BGrun1 + BGrun2 • 0.23kg∙days • Length<1cm, E>100keV • BG decrease 40% of surface @100keV blue　：　Surface Run red　：Kamioka first (preliminary) 102 cts/kg/kev/days 101

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

  16. 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:0708.2529 underground run started Total exposure 0.23 kgday up to Aug.2007 Event rate is 40% of surface run of @100keV Now background study • Future work • Reduce Rn, U, Th in detector • Larger Detector , low pressure • Low background run

  17. Thank you !!

  18. TPC performanceCF40.2atm 24×27×30cm3 • Energy resolution 50%(FWHM) @ 5~8 MeV ~70%@100keV • Position resolution 800μm (rms) • angular resolution ~15° (HWHM)

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

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

  21. 222Rn emanation and alpha from drift plane α α 232Rn 232Rn 232Rn 232Rn Fiducial area U Drift Plane Chamber U Increase of peak @ 6MeV With decay constant of Rn (3.8days)

  22. Stability(BGrun2) • Gas gain &DAQ rate: Slow decrease 10%~20% / month →correct by analysis →recover by replacing new gas Gas gain 1.4 1.0 0.5 0.1 Hz DAQ rate 1.4 1.0 0.5 0.1 5/157/1 8/2

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

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