NEWAGEdirection-sensitive dark matter search experiment

• Direction-sensitive method• NEWAGE experiment• Low pressure gas study• Summary

Kiseki Nakamura (Kyoto university)

TAUP2011@Munich　 2011/09/05

T.Tanimori, H.Kubo, K.Miuchi, T.Mizumoto, J.Parker, A.Takada, H.Nishimura, S.Iwaki, T.Sawano, Y.Matsuoka, S.Komura, Y.Sato

Direction-sensitive DM detection

θDM

Nucleus

Incoming direction of DM (new)• Nuclear track -> Gas detector• Require for 3s : ~20events

Annual modulation (conventional)• Large mass -> Solid or liquid detector• Require for 3s : ~10000events

Large differencein forward to back

Expected cosθ distribution

cos q

σSD=1pbM=100GeVtarget:F

65cm

45cm

45cm

m-TPCASD

PositionEncoder

Flash ADC

m-TPC micro-Time-Projection-Chamber

• 3-dimensional tracker• gas : CF4 (0.1-0.2atm)

NEWAGE Detector "m-TPC"New general WIMP search with an Advanced Gaseous tracker Experiment

m-PIC micro-Pixel-Chamber• size : 30x30cm• pitch : 400mm• x-y strip readout

GEM• size : 28x23cm• thickness : 50mm• hole : 70mm• pitch : 140mm

30 or 50 cm0.5cm

30cm

Kamioka underground laboratory

Kamioka status• Depth : 2700m.w.e• Low background

Particles at Kamioka• Muon : 6.0x10-8 [/cm2/s/sr]• neutron : ~10-6 [/cm2/s]• gamma-ray : ~3x10-2 [/cm2/s]• radon : 200-3000 [Bq/m3]

We get outside-air(40Bq/m3) into our experiment place

Kamioka

Cosmic muon vs depth

Kamioka

DM search up to 2010Condition• Place : Kamioka• Exposure : 0.524 [kg days]• Pressure : 0.2atm

Obtained• Energy spectrum : 50 dru @100keV• |cosq| distribution : Flat• Limit : 5600pb for 150GeV

PLB 686 (2010) 11

obtained cosq distribution

Energy spectrum at Kamioka

NextWe aim to search DAMA-region (sensitivity x~1000)

• Background : 1/10 ( x10)-> Radon elimination (sub talk) Material selection

• Energy threshold : 1/2 ( x10)-> low pressure gas (main talk)

• Large size ( x10)-> Several 1m3 size detectors ( current : (30cm)3 )

• Head-tail identification ( x3)-> New DAQ (time-over-threshold)

PLB 686 (2010) 11

Expected limit curve of the WIMP-proton SD elastic scattering cross section (90%C.L.)

Gas circulation system• Circulation with cooled charcoal

• Radon rate : 1/4 (prototype pump)

• Further reduction is expected with full spec (600ml/min) pump

Time dependence of Rn

without circulation

with circulation

Detection region(76torr CF4)

pump20ml/min

cooler210K

charcoal 160g　　・ spiral:60g　　・ cylinder:100g

Rn

U

a-decay(about 6MeV)

Rn

Detector wall

Low Pressure Experiments

Low pressure gas (152torr -> 76torr) -> Track length : x2

Advantage• Sensitive to low energy (short) tracks• Improve angular resolution

Difficulty• Electrons density : half -> Necessary gas gain : x2 (=1500)

How to make threshold lower

current threshold

new threshold (plan)

σ=1pb, M=100GeV, target:F

Expected energy spectrumEnergy threshold : 100keV -> 50keV -> Sensitivity to DM : x10

anode voltage[V]

GEM:-500/-280V

gas gain

2 times gainfrom 0.2atm

Gain curve

Angular resolution• Compare the cosq distribution between measured to simulation (simulate each angular resolution)

• We checked 50-100keV range : 40[deg](Can't be seen at 0.2atm)

cosq distribution (400-800keV)

Blue:measuredGreen:simulation(s=49deg)

q

252Cf

neutron

nuclear

Simulated cos q distribution (400-800keV)

angular resolution

Blue : This work (0.1atm)Red : Previous (0.2atm)

F nucleus tracks

252Cf

• Detection efficiency : 0.6@50keV (ratio of measured to simulation)

• Energy threshold : 100 -> 50keV

Detection efficiency angular resolution

detection efficiency

current threshold

new threshold (plan)

σ=1pb, M=100GeV, target:F

Expected energy spectrum

NEWAGE• Direction-sensitive DM search with MPDG "m-TPC"• We obtained direction-sensitive exclusion limit for DM

Gas circulation• Radon rate : 1/4 with prototype pump

Low pressure (152torr 76torr)⇒• Operation test

u-PIC work at 76torr with sufficient gain

• Angular resolution40°+3.1-2.9@50-100keV

• Detection efficiency0.6@50keVEnergy threshold : 100 -> 50keV

Next to search DAMA• Update gas circulation system for radon elimination• Use new DAQ for head-tail identification• Simulation for constructing the large size detector

Summary

NEWAGE• Direction-sensitive DM search with MPDG "m-TPC"• We obtained direction-sensitive exclusion limit for DM

Gas circulation• Radon rate : 1/4 with prototype pump

Low pressure (152torr 76torr)⇒• Operation test

u-PIC work at 76torr with sufficient gain

• Angular resolution40°+3.1-2.9@50-100keV

• Detection efficiency0.6@50keVEnergy threshold : 100 -> 50keV

Next to search DAMA• Update gas circulation system for radon elimination• Use new DAQ for head-tail identification• Simulation for constructing the large size detector

Summary

Mascot of NEWAGE"Daakumatan"

Thank you for your attention!

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