Dark Matter Search with μTPC （ powerd by μPIC ）

Micro Pattern Gas Detector 研究会　2004年 12月 3日　京都大学関谷洋之

京都大学

μTPC でとらえられるもの　

Neutral Particle

ここでは、暗黒物質　 neutralino についてのお話をします。

電子、　ミューオンHeavy Charged Particle

フォトン　 X線　ガンマ線　　　 electron recoil

Neutron　　　 proton (nuclear) recoil

Neutrino　　　 electron recoil

Neutralino 　 nuclear recoil

暗黒物質2003年　 WMAP衛星宇宙背景放射のゆらぎの測定

NASA/WMAP 　Science Team

暗黒物質（ CDM）の量は分かったがその分布や何であるのかは依然、謎．

有力候補： SUSY に予言される neutralinoの直接検出を目指した実験

暗黒物質（ニュートラリーノ）の直接検出実験　　　　　 通常の物質と弾性散乱 (相互作用 )することを利用　　　地上の検出器中の原子核の反跳を観測する銀河ハロー中の地球の動きによる“風”　　暗黒物質のシグナル

直接検出？

太陽DARK HALO(Maxwell 分布 )Ｖ０＝ 220km/s

暗黒物質の風白鳥座の方向 232 km/s 京都での今日の風向き

１２：００

０：００

１８：１０

反跳方向に現れる統計的なシグナルをとらえる

散乱された暗黒物質

反跳原子核暗黒物質の風 γ

V Ｅ

μTPC による方法

μ-TPCμ-TPC

cos

CF4(Eth=40keV)MWIMP=50GeV

Drift plane

N

N

N WIMPWIND

CF4 ガスを利用 for SD interactiong DM

Track length threshold: 3 mmdE/dx threshold: 10 keV/cm

μPIC の性能

Pressure[Torr]

Density[g/m3]

dE/dx[keV/cm]

20 90 85 低圧力での動作研究が必要

10x10x10cm3 μTPC 　ガス容器中まずは Ar+C2H6 中での 5.9keV 　 X線　

Gas gain variation

1atm0.5atm0.2atm

Ar+C2H6

(9:1)

Time [hour]

0.1 atm までの低圧でシグナルを確認ガスゲインの低下は Out-Gas の影響

60cm

Gas vessel

-TPC

低圧での動作試験

252Cf

　 YAP(trigger)

-TPC

low pressure gas n

p or C

nucleipressure [atm]

range [mm]

p 1 2.6 0.5 5.1 C 1 1.1

0.5 2.1 0.2 5.5

２００ keV 反跳に対する期待される range (SRIM2003)

Experimental setup Ar+C2H6 gas

中性子による原子核反跳

n

Bragg curves

3D tracking Bragg curves

計算した range測定した range測定した charge から　　　　　　　のエネルギーが一致している

水素反跳得られた飛跡１

炭素反跳

350keV = 8mm (SRIM)

n

Bragg curve

得られた飛跡２

gas gain>7000 @ 0.25 atm 　で　安定動作C,F 反跳飛跡取得の実験準備中です。

Gas

gai

n

800600

104

103

CF4 100%

700Anode voltage [V]

0.25 atm 0.5 atm 1 atm

Source: 55Fe (5.9keV)

Gas gain

CF4 100% (1atm)

Ar+C2H6 (1atm)

Drift velocities of electrons

Electric field [kV/cm]

CF4での基礎動作試験

SD 3 detection sensitivities

M WIMP [GeV]

W

IMP

-p [p

b]

2004 2005+ 201?

1m3 ×30 　 -TPC

R&D with 800cm3 -ray BG rejection Electron diffusion Low pressure operation

n BG measurement @ Kamioka 1m3-TPC

実験計画

hatched ： WIMPpainted ： neutron BG

cos

WIMP WIMP WINDWIND

γ γ

FF

大型化が必要　　高田

WIMP-wind Detection with an AdvancedGaseous Tracking Device

Atsushi TakedaT. Tanimori, H. Kubo, K. Miuchi,

T. Nagayoshi, H. Sekiya, R. Orito, A. Takada, Y. Okada,

H. Nishimura, K. Hattori

Kyoto University

DARK20046 October, 2004

Texas A&M University, College Station, TX, USA

Table of Contents

1. Direction sensitive WIMP search2. -TPC: 3-D tracking device3. WIMP-wind detection with -TPC4. Study with 10cm-size detector

as a WIMP-wind detector5. Summary 　

1. Direction sensitive WIMP search

Recoil energy [keV]

[cou

nts/

keV/

day/

kg]

Only a few %rate difference

Detecting only energy spectrawith a conventional detector

WIMP-wind is blowing from the direction of the Solar motion

Drift plane

μ-TPCμ-TPCN

N

N

WIMP WIND

γ γ

FF

Detecting WIMP-wind distribution with a gaseous tracking device

cos

CF4(Eth=40keV), MWIMP=50GeV

Very large asymmetry

WIMPWIND

CathodeAnode

400m

100m50m

Drift plane

electroncloud

2-D imaging detector 400m pitch electrodes simple structure stable operation large area (PCB technology)

μμ-PIC + TPC (x, y) (drift

time)

-PIC

2. -TPC: advanced gaseous device

3D tracking

μμ-TPC:

with a micro pixel chamber (-PIC) readout

-PIC, Micro Pixel Chamber

CathodeAnode

10cm

10cm

Practical size (10cx10cm2) -PICs are working well

Now, large size (30x30cm2) -PIC is being manufactured

30cm

30cm

Gas gain

440 600520Anode voltage [V]

104

103

Ar:C2H6 = 8:2

Ar:C2H6 = 9:1

(gas gain ~6000)

High gas gain max: 16000 Good gain uniformity ~4.5% () Good spatial resolution ~120m () Stable operation 　　 >1000 hours

10cm

Gain uniformity

Performance of the 10x10cm2 -PIC (1/2)

Anode [cm] Cathode [cm]

NIM A 525 (2004) 20

Performance of the 10x10cm2 -PIC (2/2)

FWHM 30%

MnK

Ar-esc

5.9keV

55Fe spectrum @ 10cmx10cm

ADC [ch]

0.5mmslits

Xe:C2 H6 = 7:3

Length along the edge [mm]

Coun

ts Knife edge test

position resolution σ=120m

X-ray image

1mm

Prototype -TPC 10×10×10cm3 detection volume

E=500V/cm10cm

10cm

10cm

0.2mmCu wires

Encoder board

ASD board

-TPC

VME Memory Board512ch

summed analog (8ch)

512chLVDS digital

32bit

DAQ system

VME FADC 100MHz 8ch

256ch (anode)256ch (cathode)

256ch (anode)256ch (cathode)

3-D tracking

Bragg curves Amplifier-Shaper-

Discriminator (ASD) chip

5 FPGAs take anode-cathode

coincidence @ 50MHz

Performance of the -TPC (1/2)

Proton tracks

electron tracks

3-D tracks obtained with Ar+C2H6 of 1atm

n

252Cf

Performance of the -TPC (2/2) Gamma-ray rejection

NIM A517 (2004) 219

nucleus eventnucleus eventdE/dX [keV/cm]

22Na (γ)

2 /d.o

.f.dE/dX [keV/cm]

χ2 /d.o

.f

252Cf (n+γ)

2 /d.o

.f.

0

10

20

30

100 200 300 400 500

χ2 /d.o

.f

0

30

20

10

100 200 300 400 500

(511keV )

Nucleus events have large dE/dx

straight track

3. WIMP-wind detection with -TPC

Comparing to the other experiment

Our -TPC DRIFT project

Fine pitch (400m) 3-D tracking Mechanically stable

Mass production (PCB technique)

First detector with sensitivity to the directions of nuclear recoils MWPC with 2mm pitch 2-D tracking only

wireless, no 3-D geometry

as of shown in PLB 578 (2004) 241

Experimental parameters used for the calculation

Detection sensitivities

Target gas: CF4 for Spin-dependent (SD) interaction

Track length threshold: 3 mm dE/dx threshold: 10 keV/cm -ray discrimination ~100% Bragg curves are detected

gas Pressure[Torr]

Density[g/m3]

dE/dx[keV/cm]

CF4 20 90 85

Need to study low-pressure -TPC

Expected WIMP signal

WIMP WIMP WINDWIND

γ γ

FFhatched ： WIMPpainted ： neutron BG

cos

/sn/cm 10)21.091.1( 26 @Kamioka

CF4 20Torr Fast neutrons are the only BG source

50cm water shield Forward/Backward asymmetry

Detection sensitivities

Spin-dependent

M WIMP [GeV]

W

IMP

-p [p

b] Estimated 3 detection sensitivities at Kamioka Observatory for SD interaction

4. Study with 10cm-size detectoras a WIMP-wind detector

Operation with low-pressure gas

3-D tracking with low-pressure Ar+C2H6 gas

Operation with CF4 gas including 19F whose large cross section for SD interaction

Required operation pressure: 0.05 ~ 0.2 atm

Confirm tracking capabilities under low-pressure using a standard gas

Properties of CF4 gas

Operation with low-pressure gas 10x10x10cm3 -TPC in the gas vessel Gas vessel is available for 30x30 cm2 detector

60cm

Gas vesselGas gain variation

1atm0.5atm0.2atm

Ar+C2H6

(9:1)

Time [hour]

Signals were observed down to 0.1 atm Out-gas should be suppressed

-TPC

252Cf

　 YAP(trigger)

-TPC

low pressure gas n

p or C

nucleipressure [atm]

range [mm]

p 1 2.6 0.5 5.1 C 1 1.1 0.5 2.1 0.2 5.5

Calculated range of nuclei whose energy of 200 keV (SRIM2003)

3-D tracking with low-pressure Ar+C2H6 gas

Experimental setup

Obtained 3-D tracks (1/2)

n

Bragg curves

3D tracking Bragg curves

range v.s. chargeroughly agrees with SRIM

tracks of recoil protons

Carbon candidate

350keV = 8mm (SRIM)

n

Obtained 3-D tracks (2/2)

Bragg curve

Stable operation with gas gain>7000 @ 0.25 atm Confirmed drift velocities of electrons in CF4 gas are fast

Gas

gai

n

800600

104

103

CF4 100%

700Anode voltage [V]

0.25 atm 0.5 atm 1 atm

Source: 55Fe (5.9keV)

Gas gain

CF4 100% (1atm)

Ar+C2H6 (1atm)

Drift velocities of electrons

Electric field [kV/cm]

Operation with CF4 gas

4. Summary WIMP-wind detection

-PIC has a fine pitch (400 m)

Study with 10cm-size detector Low pressure operation (0.2 atm) Proton and carbon 3-D tracks Properties of CF4 gas

30cm-size TPC will be ready at the end of 2004

Organic scintillators　 - Minowa group (Tokyo)

Gas detectors　 - DRIFT （ UK ）　 - -TPC （ Kyoto ）

-PIC with -PIC with 400400mm pitch pitch

3-D tracking3-D tracking Mechanically stableMechanically stable

UKDMC, Occidental College, Temple Univ., LLNL First detector with sensitivity to First detector with sensitivity to

　　 thethe 　　 directions of nuclear recoilsdirections of nuclear recoils

MWPC with MWPC with 2mm2mm pitch pitch

2-D tracking only2-D tracking only

DRIFT project Our -TPC

wireless, no 3-D geometry

Mass productionMass production

Direction sensitive detector under development

n

Anode [cm]

Drif

t [c

m]

Cathode [cm]

Time schedule

SD 3 detection sensitivities

M WIMP [GeV]

WIM

P-p

[pb]

SI 3 detection sensitivities

M WIMP [GeV]

W

IMP

-n [p

b]

2004 2005+ 201?

1m3 ×30 　 -TPC

R&D with 800cm3 -TPC -ray BG rejection Electron diffusion Low pressure operation

“Detection” by Forward/Backward 3σasymmetry

n BG measurement @ Kamioka 1m3-TPC

• track direction is important

track onlytrack only

track+directiontrack+direction

F/B ~ 5F/B ~ 5

F/B ~ 1.3F/B ~ 1.3

• Expected rate– threshold: 40keV– WIMP mass: 50 GeV for F, Ar

　　　　　　　　　 100GeV for Xe 　– WIMP- ｐ cross section : 0.1 pb for SD

　 　 　　　　　　　　　　 10-6 pb for SI

gas pressure[torr]

density[g/m3]

rate[cpd/kg]

Event(10m3×1yr)

CF4 20 90 0.21 260

Ar 20 47 0.034 4.1Xe(SD) 5 10 0.011 1.4Xe (SI) 5 38 0.079 9.6

• S/N calculation – threshold: 40keV– WIMP mass: 50 GeV for F, Ar

　　　　　　　　　 100GeV for Xe 　– WIMP- ｐ cross section : 0.1 pb for SD

　 　 　　　　　　　　　　 10-6 pb for SI

gas Event(30m3×3yr)

F/B ratio

Modulation(σ)

n BG ×1/100

CF4 2340 14 20σ 40σ

Ar 37 11 0.4σ 3σXe(SD) 13 5 0.1σ 1σXe (SI) 86 5 0.4σ 5σ

• Expected 95 % C.L. sensitivities

Spin-Dependent Spin-Dependent Spin-Independent Spin-Independent

Xe 30 m3, 3 years35cm water shield

Xe 10 m3, 1 yearnoshield

CF4 10 m3, 1 yearnoshield

CF4 30 m3, 3 years35cm water shield

spectrum spectrum

• Threshold dependency of F/B

gas: CF4 WIMP-p: 0.1 pb

forward/backward increases with theincreases with the threshold energythreshold energy