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J.L. Raaf SK Group Meeting January 11, 2008
The other dark matter experiment in Kamioka Mine: NEWAGE
Direction-sensitive search for spin-dependent WIMP interactions
Why “direction-sensitive” ?
Motion of solar system relative galactic halo gives apparent “WIMP-wind”
WIMP-wind will appear to come from the direction of CygnusAngular distribution of nuclear recoils (from WIMP scattering) canreveal presence of dark matter!
NEw generation WIMP-search with an Advanced Gaseous tracking device Experiment
J.L. Raaf SK Group Meeting January 11, 2008
μ-TPC detector gaseous (CF
4) time projection chamber
Nucleus scatters in gas, causing e- cloud along trackCloud pulled down by drift field (~200V/cm)
active gas volume: 23 x 28 x 31 cm3
2-D position + time = 3-D readout
NEWAGE Detector
μ-PIC (μ-PIxel Chamber)used for amplification and readout
gas gain ~1000400 μm pitch768 'x' channels768 'y' channels
GEM (Gas Electron Multiplier) used as pre-amplifier (gas gain ~10)
digitized by ASD chipsreadout sync w/100 MHz clock
Position resolution: 800 μmAngular resolution: ~15 degrees
J.L. Raaf SK Group Meeting January 11, 2008
NEWAGE Performance
Proton tracks
n
252Cf source
Y
-15cm
30cm
0cm
Jan 27, 2007 3rd MPGD workshop
252Cf(NE45° zenith35°)
CF4+C4H10
252Cf run
Z(d
rift
)
X(anode) Y(cathode)15cm
Sky map shows large excess in direction of source
Angle between source and reconstructed proton trackpeaks in direction of source
Demonstration of directional sensitivity for dark matter searches with a gaseous detector
n → p forward scattering (emulates WIMP scattering)
cos θ
J.L. Raaf SK Group Meeting January 11, 2008
NEWAGE Results & Plans
Surface run consistent with flat distribution Kyoto Univ. 0.15 kg-days exposure
(0.0089 kg x 16.7 days)
Set limit on spin-dependent WIMP-proton σ(surface run: not competitive)
Since then, moved detector to KamiokaBackground studies underway:
radon, alphas, gammas, neutrons
Future planned improvements: larger detector volumelower gas pressure (allows for lower energy threshold)reduce radon background by circulating gasupgrade readout (VME bus → KEK-designed ASIC)
Present and Future
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