Applications of Micro-TPC to Dark Matter Searchumehara/ndm03/... · 2005-07-28 · 1. WIMP...

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Applications of Micro Applications of Micro - - TPC TPC to to Dark Matter Search Dark Matter Search 1. WIMP signatures 1. WIMP signatures 2. Performance of the Micro 2. Performance of the Micro - - TPC TPC 3. WIMP 3. WIMP - - wind measurement wind measurement 4. Future works 4. Future works 5. Conclusions 5. Conclusions Jun. 13, 2003 Jun. 13, 2003 Atsushi Takeda Atsushi Takeda for the for the μ μ - - PIC group PIC group

Transcript of Applications of Micro-TPC to Dark Matter Searchumehara/ndm03/... · 2005-07-28 · 1. WIMP...

Page 1: Applications of Micro-TPC to Dark Matter Searchumehara/ndm03/... · 2005-07-28 · 1. WIMP signatures Annual modulation Very hard to see… Movement of the earth Expected spectra

Applications of MicroApplications of Micro--TPCTPCtoto

Dark Matter SearchDark Matter Search1. WIMP signatures1. WIMP signatures2. Performance of the Micro2. Performance of the Micro--TPCTPC3. WIMP3. WIMP--wind measurementwind measurement4. Future works4. Future works5. Conclusions5. Conclusions

Jun. 13, 2003Jun. 13, 2003Atsushi TakedaAtsushi Takeda  for the for the μμ--PIC groupPIC group

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1. WIMP signatures1. WIMP signatures

Annual modulationAnnual modulation

Very hard Very hard to seeto see……

Movement of the earth Movement of the earth

Expected spectraExpected spectra

rate difference is a few %BGs themselves arelikely to have it

based on the motionof the earth aroundthe sun

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WIMP-wind

WIMP-wind

WIMP-wind

blowing from the directionof the solar motion

WIMPWIMP--windwind

Strongly peaked in

the Cygnus direction

A directional sensitivedetector is needed

WIMPWIMP--wind distributionwind distribution

180 -180

-90

90

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2. Performance of the Micro2. Performance of the Micro--TPCTPCMicro-TPC = μ-PIC + TPC

Schematic structure of the μ-PIC

Micro pattern gas detectorFine position resolution

(400 μm pitch)2D imaging

Micro Pixel Chamber (Micro Pixel Chamber (μμ--PIC)PIC)  

MicroMicro--TPCTPC  

μ-PIC: X, YTPC: Z (drift time)

3D tracking

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10×10cm2

TPC gas package

10×10×8cm3 Micro-TPChas been developed

Pictures of the MicroPictures of the Micro--TPCTPC10×10cm2 μ-PIC

readoutTPC

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3D Tracking performance3D Tracking performancetrack length > 5 mm (several points, direction)

ProtonProton trackstracks

neutron

dE/dxdE/dx (Brag curves)(Brag curves)

neutron

Ar : C2H6 = 9 : 1 (1 atm)

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252252Cf run (Cf run (n+n+γγ))

dE/dx [keV/cm] 5000

χ2 /d

.o.f

300

neutron0

0

2222Na run (Na run (γγ))

dE/dx [keV/cm] 500χ

2 /d.o

.f30

γγ--rayray  discriminationdiscriminationχ2 vsvs dE/dxdE/dx plotplot

neutron events havelarge dE/dxstraight track

neutron( 14 / 500 events )

>95% >95% γγ--rays were rays were discriminateddiscriminated

n efficiency ~ 1n efficiency ~ 1

(511 keV γ)

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3. WIMP3. WIMP--wind measurement wind measurement with Microwith Micro--TPCTPC

MeritMeritrecoil track and directionrecoil track and directionγγ--rayray discriminationdiscriminationfine pitch (400fine pitch (400μμm) m) ⇔⇔ DRIFT(2mm)DRIFT(2mm)Mass productionMass production

DemeritDemeritlow mass (gas detector)low mass (gas detector)

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Target gasTarget gasSpin-dependent (SD): CF4, XeSpin-independent (SI): Xe

Gas pressure, target massGas pressure, target massthreshold: 40 keVtrack: 5 mm

pressurepressure

38389090

DensityDensity[g/m[g/m33]]

dE/dxdE/dx[[keVkeV/cm]/cm]

PressurePressure[[TorrTorr]]

gasgas

12012055XeXe85852020CFCF44

((μμ-- PIC threshold : 50keV/cm)PIC threshold : 50keV/cm)OK~ 10~ 10××1m1m33 detector detector

is neededis needed

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~ 10~ 10××1m1m33 detectordetectorprototype : 30prototype : 30××3030××30cm30cm33

large area large area μμ--PIC : 50PIC : 50××5050××50cm50cm33

                            ××8 = 1m8 = 1m33

1m1m33××1010

drift planeμ-PIC

×8electronics

1 m3 volume50cm

50cm50cm50cm50cm

modularizemodularize

×10 modules

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spectrum spectrum

threshold threshold

recoil asymmetry recoil asymmetry

forwardbackward

WIMPWIMPWINDWIND

γγ

FF

Expected signalsExpected signalsfor SD interactionfor SD interaction

gas: CF4WIMP-p: 0.1 pb

forward/backward forward/backward >10>10

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800800

2020 240240

800800

1040104082082011--11 00

coscos γγ

more than 5more than 5σσasymmetryasymmetry

Backgrounds: fast neutron 22××1010-5cmcm-2ss-1@Kamioka@Kamioka⇒⇒ 0.1 0.1 cpd/kg/keVcpd/kg/keV for CF4 (10cm water shield)for CF4 (10cm water shield)

           ⇒⇒ 16001600 BG events / 10mBG events / 10m3××1yr1yr

WIMPs: 260 events / 10m/ 10m3××1yr1yr

CFCF44 detection possibilitydetection possibility

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Estimated detection possibilityEstimated detection possibility

5σ 2σ

SI SD

Xe 10 m3, 1 yearnoshield

Xe 30 m3, 3 years35cm water shield

CF4 10 m3, 1 yearnoshield

CF4 30 m3, 3 years35cm water shield

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4. Future works4. Future works

Gas studyGas studyCFCF44 propertiesproperties

Background studyBackground studyγγ--rayray discriminationdiscrimination

Study of the diffusion effectStudy of the diffusion effectinfluence on the sensitivityinfluence on the sensitivity

Energy CalibrationEnergy Calibrationtrack length v.s. energytrack length v.s. energy

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5. Conclusions5. Conclusions

WIMPWIMP--wind measurementwind measurementidea : NOT NEWidea : NOT NEWμμ--PIC has a fine pitch (400 PIC has a fine pitch (400 μμmm))

MicroMicro--TPCTPCsensitive to SD and SIsensitive to SD and SIfactor 10 forward/backward asymmetryfactor 10 forward/backward asymmetryCFCF44 55σσ detection possibilitydetection possibilityprecise studies to doprecise studies to do

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diffusion for diffusion for 5050××5050××50cm50cm33 MicroMicro--TPCTPC

D: diffusion coefficientt: drift time Dtr 6)( =σ

drift velocity of e- in pure CF4 ~ 10 cm/μsec

50 cm t ~5μsec

diffusion coefficient: D ~1.5×10-3 cm2/μsec

=)(rσ ~ 2

It’s not so large

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7.7 7.7 McpsMcps

X-ray intensity[mA]

DA

Q r

ate[

MH

z] 8

030cm30cm

40cm40cm

Position encoding modulePosition encoding module-- 5 5 FPGAsFPGAs 40MHz clock40MHz clock

Readout electronicsReadout electronicsPreamplifierPreamplifier-- ATLAS amplifier shaper ATLAS amplifier shaper discriminator (discriminator (ASDASD) chip ) chip (64ch/card)(64ch/card)

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track onlytrack only

track+directiontrack+direction

F/B ~ 5F/B ~ 5

F/B ~ 1.3F/B ~ 1.3

track direction is track direction is importantimportant

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Expected rateExpected ratethreshold: 40keVthreshold: 40keVWIMP mass: 50 WIMP mass: 50 GeVGeV for F, for F, ArAr                  100GeV for 100GeV for XeXe  

WIMPWIMP--pp cross section : 0.1 cross section : 0.1 pbpb for SDfor SD                           1010--6 6 pbpb for SIfor SI

4.14.10.0340.03447472020ArAr1.41.40.0110.011101055Xe(SDXe(SD) )

55

2020

pressurepressure[[torrtorr]]

0.0790.079

0.210.21

raterate[[cpdcpd/kg]/kg]

EventEvent(10m(10m33××1yr)1yr)

densitydensity[g/m[g/m33]]

gasgas

9.69.63838XeXe (SI)(SI)

2602609090CFCF44

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S/N calculation S/N calculation threshold: 40keVthreshold: 40keVWIMP mass: 50 WIMP mass: 50 GeVGeV for F, for F, ArAr                  100GeV for 100GeV for XeXe  

WIMPWIMP--pp cross section : 0.1 cross section : 0.1 pbpb for SDfor SD                           1010--6 6 pbpb for SIfor SI

0.40.4σσ

0.10.1σσ

0.40.4σσ

2020σσ

ModulationModulation((σσ))

33σσ11113737ArAr

86861313

23402340

EventEvent(30m(30m33××3yr)3yr)

5555

1414

F/B F/B ratioratio

11σσXe(SDXe(SD) )

n BG n BG ××1/1001/100

gasgas

55σσXeXe (SI)(SI)

4040σσCFCF44

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Expected 95 % C.L. sensitivitiesExpected 95 % C.L. sensitivities

SpinSpin--Dependent Dependent

CF4 10 m3, 1 yearnoshield

CF4 30 m3, 3 years35cm water shield

SpinSpin--Independent Independent

Xe 30 m3, 3 years35cm water shield

Xe 10 m3, 1 yearnoshield

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spectrum spectrum

forward/backwardincreases with theincreases with thethreshold energythreshold energy

Threshold dependency of F/BThreshold dependency of F/B

gas: CF4WIMP-p: 0.1 pb