NEWAGE -- A direction-sensitive dark matter search
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Transcript of NEWAGE -- A direction-sensitive dark matter search
K. Miuchi
NEWAGE -- A direction-sensitive dark matter search
Kentaro Miuchi
( Kyoto University)H. Nishimura
T. Tanimori, H. Kubo,
S. Kabuki, K. Tsuchiya,
A. Takada, Y. Okada,
K. Hattori, K. Ueno, S. Kurosawa
A. Takeda (ICRR), H. Sekiya (ICRR)
(New generation WIMP search with an advanced gaseous tracker experiment)
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OUTLINE
Introduction
Detector
NEWAGE surface run
FUTURE PLANS & SUMMARY
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Introduction: Direct DM search in 2010’s
What happened in 2000’s…
<1> DAMA (~100kg) : 7 years’ result <3> LIBRA (post DAMA):
<2> “challenge DAMA” (~10kg):CDMS, EDELWEISS, XENON10
YESsearch **GeV ! atLCH, GLAST
NONO NO
Please for SUSY
What will happen in 2010’s
YES
NO
<4> “challenge SUSY” (~100kg): SUPER**, **0
BACK to <1>
YES, but not conclusive…
<5> use various nuclei, and
or, MAYBE
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1 . Direction sensitive DM search “ WIMP-wind” detection
The WIMP-wind
WIMPV0 =230 km/s
SOLAR SYSTEM220 km/s
PLB 578 (2004) 241
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WHY “Direction-sensitive” ?Large mass for exclusion ( and indication )
BUT Annual modulation is not enough…
Direction-sensitive for detection
WIMPWIMP WIND WIND γ γ
FF
Annualmodulation
direction
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Sensitivities Goal: Detect the WIMP-wind ( 2010~ )
• underground ・ low pressure ( CF4 0.05 bar ) ・large volume ( 1m3 × N )
CURRENT: • surface ・ CF4 0.2 atm ・ 30cm cube
sensitivity
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2. DETECTOR
June 22, 2007 SUSY in 2010’s
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2 micro-TPC (3D tracking device)
Feb. 20, 2007 APPEAL07
Position Encoder
PIC (×5000)
GEM(×10)
TPC
Particle tracks
e
Preprints: physics/0701085 K.Miuchi et.al
40cm
TPC
X readout ( 768ch ) Y
readout ( 768ch )
FAGA position encoder( 1536ch )
23×28×31cm3
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Readout electronics• 768 anode + 768 cathode• Digital (LVDS) signals at ASD• (X,Y,T) at the position encoder
31cm
gas volume
TPC system
Gas volume• DRIFT length 31cm• CF4 0.2bar gas
100MHz, pipeline
2D imaging device: -PIC (gas gain 5000)
• 400mm pitch• 589824 pixels• 768+768 readout
30cm μPIC(Toshiba)
CF4+C4H10 (9:1) 0.2 atm
n -> p forward scattering (emulation of WIMP -> F scatterings)
Jan 27, 2007 3rd MPGD workshopRecoil direction image
252Cf( NE45° zenith35° )
10
Cos
n
p
CF4+C4H10
252Cf run
Proton tracks
n252Cf
YX-15cm
15cm
15cm
-15cm
30cm
Z(drift)
0cm
TPC performance 1: nuclear tracks, imagingPreprints: physics/0701118 K.Miuchi et.al
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TPC performance 2: gamma-ray rejection
energy length correlation
gamma-rays from 137Cs
neutron ( BG )
neutron ( BG )
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gamma-ray rejection ( continued )spectrum, BG subtrucction
• gamma rejection < 2e-4 ( statistics limited )
neutron ( BG )
Subtracted energy spectrumEnergy spectrum
thick: 137Cs run
hatched: no source
consistent with 0 ( >100keV )
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3. SURFACE RUN
June 22, 2007 SUSY in 2010’s
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Surface run①2006 Nov.1st ~ Nov.27th
exposure 0.15 kg days (=0.0089kg ×16.7days)
@Kyoto university (N35.03 E135.783 ) Energy spectrum ( conventional method )
Energy spectrum
3 Surface run
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Surface run ②The sky map (by nuclear recoil tracks)
flat neutron background is seen
North sky view seen by C and F nuclei(100-400keV)
DM direction
Jan 27, 2007 3rd MPGD workshop
Surface run ③Cosθ distribution
consistent with a flat distribution
Cosθ 分布
(100-400keV)
DM limit
First step to theNEWAGE
WE ARE HERE
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KAMIOKA LAB-B
Underground run @ KAMIOKAData taking since January 2007.
low background material selection
background neutron measurement
4 Next step…
TPC improvements @ KYOTOlarger TPC (30cm cube -> 60cm cube)
lower threshold (100keV -> 30keV)
readout ASIC (with KEK)
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SUMMARYμTPC : 30cm cube in operation
direction-sensitive method works!
NEWAGE : underground run just started
AcknowledgementThis work was partially supported by Grand-in-Aid for Scientific Research on Priority Areas: "Discoveries of Higgs Particles and Supersymmetry to Pioneer the Particle Physics in the 21st Century"
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20062006 年年 1111 月月 1717 日日
TPC performance ② stability
Drift velocity: fast drop
⇒ slow decrease after 1 day
gain, energy resolution : stable within the systematic error
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TPC performance: nuclear track efficiencyneutrons from 252Cf
• 0.4 @ 100keV
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エネルギー校正• ガラスに蒸着した 10B ( 厚さ 0.6μm )• ドリフトケージ内部にセット、外から 252Cf の中性子を減速して照射• 10B(n,a)7Li 反応 (Q=2.70MeV 1.8MeV for )• 原子核による校正、低エネルギーへの線形性は別途確認示す必要あり• 現状では、校正には 6 時間程度、見せれる絵には 12 時間程度かかって
いる
XY イメージ
keV
スペクトル
エネルギー vs 飛跡長
keV
Li
2000
スペクトル(GEANT4 )
検出器応答
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位置分解能から角度分解能• アルファ線の飛跡を直線フィット、残差を求める: 0.8mm• BG run の C,F recoil での 飛跡長 / (nhit-1) = 1mm ( サンプリング密
度 )
• 上記二つのパラメータをもちいてsimulation 振る。
• NHIT=3 で直線 FIT すると左の様になる。
• ローレンツィアンで FIT して、 γ=25°(=HWHM)
検出器応答
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エネルギー分解能• 高エネルギー( 5-8MeV )ではラドンのピークを使ってモニタ• 40 % FWHM• これは検出器固有の数字(ゲインのばらつきが効いている)
• 低エネルギーでは、以前の Ar での実測 60 % FWHM@60keV• これが電子数統計とすると、
W 値、エネルギーで外挿すると、 60×sqrt((54/26)×(60/100)) = 70 % FWHM @100keV
60%@59.5keV
検出器応答
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Gas gains • operation gain for MIPs ~50,000
Gain curves
Gain map
Gain uniformity • Maximum / minimum = 2.2
TPC performance (with Ar+C2H6 gas)
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TPC performance① tracking400m digital “HIT” ( for tracking) + summed analog ( for energy)
F 500keV 5~6mm in 0.2atm CF4
F,C tracks
n
252Cf
YX-15cm15cm
15cm
-15cm
30cm
Z(drift)
0cm
X,Y image Z projection
Fidutial 24×21.5×31cm3
(CF4 8.9g)FLAT response
trigger
Trigger :z=0
cm 30
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• gamma rejection < 2e-4 ( statistics limited )
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データ シミュレーション
クロスセクション
検出器の方向依存感度マップ
測定値
「 DM の風」
測定値
×
sim
=
sim
Expected 「 DM の風」
sim
Expected cosθ 分布( DM )
Input: エネルギー分解能、角度分解能、
WIMP 質量、エネルギー BIN
Input: エネルギー BIN 、絶対検出効率
For given WIMP 質量、
反跳エネルギー
WIMP 質量、エネルギーBIN
ごとに用意
比較
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Jan 27, 2007 3rd MPGD workshop
SpectraSpectra• Energy spectra from the whole volume
(with energy corrections)
109Cd
linearity
Energy resolution
133Ba
241Am
Ag-KCu-K
Cs-KCu-K
Cu-K
59.5keV
60%@59.5keV
22.2+24.9keV
31keV
8keV
Jan 27, 2007 3rd MPGD workshop
Particle TrackingParticle Tracking muons
Electrons (~100keV)
Protons (~2MeV)
30cm
Neutrons( 252Cf )
511keV ‘ s( 22Na )
Cosmic ray muons
Jan 27, 2007 3rd MPGD workshop
3D Spatial resolution3D Spatial resolution• Fit muon tracks with straight lines• plot the residuals
Residual muon tracks
dataFitted line
data
residual
Residual (short drift)
Residual (long drift)
)2
exp(2
222 rr
22222 )( lDdetectordiffusiondetector
Drif
t le
ngth
-PIC
mm1
mm2
mm51.0detector
cmmm/37.0D
)2
exp(2
222 rr
dependence on drift length
r [cm]
r [cm]
l [cm]