the other dark matter experiment in kamioka mine:...

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