Polynomially Homomorphic Signatures Dan Boneh Stanford University Joint work with David Freeman.
Applications of Micro-TPC to Dark Matter Searchumehara/ndm03/... · 2005-07-28 · 1. WIMP...
Transcript of Applications of Micro-TPC to Dark Matter Searchumehara/ndm03/... · 2005-07-28 · 1. WIMP...
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
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
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
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
10×10cm2
TPC gas package
10×10×8cm3 Micro-TPChas been developed
Pictures of the MicroPictures of the Micro--TPCTPC10×10cm2 μ-PIC
readoutTPC
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)
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)
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)
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
~ 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
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
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
Estimated detection possibilityEstimated detection possibility
5σ 2σ
SI SD
Xe 10 m3, 1 yearnoshield
5σ
5σ
Xe 30 m3, 3 years35cm water shield
CF4 10 m3, 1 yearnoshield
CF4 30 m3, 3 years35cm water shield
5σ
5σ
2σ
2σ
2σ
2σ
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
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
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
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)
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
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
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
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
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