3.3 - PandaX Dark Matter Experiment

Report
An Array of Bolometers for Rare
Event’s Search
Peng Haiping ,Xuzizong
State Key Lab. of Particle Detection and
Electronics(USTC)
Collab. Innova. Center for Particles and Interactions
1 Introduction
2 Bolometers for Rare Event Search
3 Outlooks
1. Introduction
• Interactions of Particles with Medium of
Detector
• Heat(phonons) is really responding to energy
deposit of particles in the detector
• Bolometer is most powerfull detectors with
high energy resolution and low energy
threshold in energy measurement
• 2D-output’s Bolometer of high capability to
identify NR from ER events
Introduction1
§1.1 Interactions of Particles with Medium of Detector
Elastic collisions : NR-Nuclear Recoils or ER- electron recoils
Energy deposit in detector
ER
Mean phonon enengy: ɛp =2.7kBT =0.23meVK-1
In the Debye approximation
Inelastic collision : a small amount of deposit energy for ionization
Ar:26eV/ion pair
Semicon.Si: 3.6eV/e-h pair ,30% Ed for e-h pair and 70% Ed
for phonons
Scinti.Crystal: a small amount of deposit energy Ed for
fluor. Photons: 40000/MeVx3eV=0.12~12% for photons and
88% for phonons
Introduction2
Bolometer
- the detectors are based on phonon or quasi-particle’s measurement
Semiconductor -D
- the detectors are based on eletcron–hole pair’s measurement
Gas detetor
- the detectors are based on electron - ion pair’s measurement
Scintillaton-D
- the detectors are based on fluoresence photon’s measurement
Introduction3
§1.2 Bolometer : realy responding to energy deposit
Energies for Phonons =Recoil energy +additional NpeV
EQ
E P  E R  eN pV b  E R 
eV b

Y  EQ / E R
E P  E R  eN pV b  E R (1 
Y

eV b )
For scintillation medium, Y even small of a few percentage.
Introduction4
§1.3 Bolometer: High energy Resolution and Low
enengy threshods
According to the statistics:
The measurement statistics accuracy FWHM:
F is Fano facctor of O (1), N is the numbers of statistics samples,
w is the mean energy spent in e-h, e-ion pair and phonon production
w=
26eV forAr-gas D
3.6eV for Si-semi.D
~meV for phonon and Quasi particle-D
Bolometer(Micro-calorimeter) has largest samples of phonons or
quasi-particles for a given Ed .So It has the highest enengy resolution
and lowest energy threshold over all other detectors
Introduction5
Example1
一个用蓝宝石(32克) 做吸收体,用W-TES(SPT)传感器的微量热器(@12mK)
对Al,Ti等荧光的响应(b)和它们典型的脉冲波形(a)
High Resol.
Low thresh.
图2.6 蓝宝石+W-TES微量热器的输出波形(a)上升,微妙,下降几毫秒(两种衰减成分) ;
以及对Al,Ti和Mn元素的特征X-射线的响应。对0.5 keV 谱线可见(b)
Colling P, et al. Nucl. Instrum. Methods A354:408 (1995)
Introduction6
§1.4 2D-readout Bolometer, High Capability to identify
NR from ER events
Most of dielectric crystals with a proper Debye temperture θ could be as
the absorbers of Bolometer. There are three kinds of crystals could be
chosen :
1. Semiconductor with diode junction :
there are 2 signals produced in the absorber for one hit event:
Heat signal proportional to ER and charge signal proportional to YER.(Y~0.3).
2. Scintillation crystal:
there are 2 signals produced in the absorber for one hit event :
Heat signal proportional to ER and fluores.signal proportional to YER.(Y~0.02).
3. Other without e-h pair and fluores.light produced
Heat signal proportional to ER only (CUORE-TeO2)
Introduction7
A bolometer with heat and charge signal readouts for one event
Y值和反冲的类型有明显的依赖性
ER-zone
[email protected]
制作的双信号同时测量显示的1334个电子型反冲
(60Co伽玛)事件(黑X) 和616中子引起和反冲型
事件(灰点) 在相对电离能损(Y)和反冲动能的两维
散点图[1]
Phonon
ER-zone
Charge
[1] D. Abrams, et al. Phys. Rev. D66, 122003 (2002)
Introduction8
A bolometer with heat and fluorescensce photon signal’s
readouts for one event
ER-zone
NR-zone
2D readouts is able to discriminate NR events from ER events
G.Anglober et al.,Eur.Phys. J ,C(2012) 72:1971
2. Bolometers for Rare Event Search
• A BGO bolometer Searching for Rare α-Decay
• A CaWO4-Bolometer for Dark Matter Search
• A TeO2-Bolometer Searching 0ν ββ Decay
§2.1 A BGO bolometer searching for rare α-decay
一直到2003年 Orsay Cedex 实验室采用2D-BGO bolometer 确认209Bi的
α衰变之前,人们普遍认为209Bi核素是稳定的最重的天然同位素。
他们在研发用于暗物质寻找的2D读出的BGO-Bolometer时,
在复杂的背景谱中,确认了一条3.137MeV的α-谱线是有
209Bi核素发射的。
Letter to Nature 2003
§2.1
NTD-fluo. sensor
NTD-heat sensor
§2.1
46g BGO-bolometer running 100hrs
a 2D (light S.~heat S.,ER) display of background events
From event scater plots a
High fluo-quench NR evts
are seperated fron ER-evts
From Spectra b up-trace
shows the mixed evts and
down-trace shows evts
with high fluo-quench(
plot a evts under the
dot-dash line
3Bq/kg 207Bi ER-evts
Trace α-isotopes NR-evts
Neuton BK –low energy
NR-evts
b Spectra of energy deposits ER of background
3.137MeV α-line from
majourity target nuclides
209Bi
§2.1
According the number of target nuclides of 209Bi containing in 46g-BGO bolometer
and running time,courting the numbers of α-evts collected.The half life time of 209Bi
T1/2=(1.9+-0.2)x1019years
§2.1
1. LAS 60m altitude
EC-evts of 207Bi 15,88keV
ER-60CO
NR-neutron
Potential for D.M Search
23 51keV
2. A seperation NR-evts from ER evts is guaranteed down to 23keV(CL >90%)
up to 51keV(CL.>99.99%)
§2.2 A CaWO4-Bolometer for Dark Matter Search
E0-ER
 + 
→  + 
E0
1
2
 = 0 1 −  1 − 

ER
,  =(
 − 2
)
 +
ER(θ=0)=0 ; ER(θ=180)= (1-α)E0
带电+Z 的反冲核获得动能E(R)从0一直到ERMAX连续分布。而且是低反冲
动能的事件占优势
§2.2
Spectra of N-Recoiller (Evt’s rate via ER) is Mχ -and MT’-s dependent
Evt’s rates are very low: cournts /10kg year!!!
Energy thresholds have to be in range of <a few tens keV
N.MIRABOLFATHI , arXiv1308.0044v1 31 Jul.2013
§2.2
CRESS
§2.2
CA- A array of bolometers
CR-Cryostat
CF-A cold Finger link CR to bolometer
CU-/PB-/PE:Copper/Lead/Polyethylene shield
RB-Gas-tight box from Rn –gas
MV-Scintillation counter Veto Cosmic rays
CRESS setup
CRESS
§2.2
eγ-BG band
One of a calbration 2D plot
Acc.
Neutron from AmB
Low
high
CRESS
§2.2
eγ-BG band
Acc. 12.9 to40kev
6evts accepted
CRESS
§2.2
Acceptance:
from Emin to 40keV
CRESS
§2.2
2D-bolometer is an
able to identify various Bk
CRESS
§2.2
M1
Mχ=25.3GeV
σwN=1.6x10-6pb
M2
Mχ=11.6GeV
σwN=3.7x10-5pb
CRESS
§2.3 A TeO2 bolometer searching for 0ν ββ Decay
The CUORICINO is a prototype of CUORE.
The target nuclide:130Te
§2.3
FWHM=7keV for crystals of 5x5x5 and 9keV for one of 3x3x6 cm at 2615 keV
§2.3
§2.3
For 0νββ search eγ BK
Is not able to discrimated
But trace α-BK could be
Problem if 1D only
Target Nuclide be selected
Q>2615keV !!
§2.3
60Co(1170+1330)
63
has to be avoided BG of the signals of 0νββ evts of 130Te
Cu(n,α)60Co, 2 γ from 60Co will contribute BK to the sgnals.
Cu-shielder has to be store in proper place where is neutron free
And make sure there is no trace of 60Co
3. Outlooks
• Prelimilary consideration about DBD-search
• 2D readout of an Array of bolometers
• R&D of key Techs -Scintill. and thermosensors
§3.1 Prelimilary consideration about DBD-search
2νββ
0νββ
2νββ-second order weak Interac.
0 νββ-1 lepton number-violation,2 Majorana /Dirac
§3.1
Basic Physics to be explored:
Theory expect
Experiment determination of T1/2
1 Determine the neutrino mass or set its up limit
2 Inform about the neutrino mass order
3 Information on Majorana CPV phase
Invert
Normal
Mass order
§3.1
2νββ has been observed
§3.1
0νββ-not observed .set the limits to T0νββ and <mν>
其中a是同位素丰度,M[kg]是 衰变物质质量,W[g/mol]是同位素的摩尔质量,
ΔE[keV]是 附近的能窗宽度,B[keV kg y]-1是本底计数率,t[y]是测量的有效时间。
nσ是实验的标准方差数, nσ =3 ,置信水平99.73%
提高探测器在Qββ能窗区的能量分辨(ΔE小),压低该区的背景事例率(b)
可以大大提高T0νββ的測量限。
The limits far from the expected ones by theroy ,1026~28 years
So the experiment search is still long way to go
§3.1
Lisa J. Kaufman
arXiv:1305.3306v1
§3.2 2D- readout of an Array of bolometers
BK problems for experiments of the target nuclide 76Ge
Qββ=2039keV
Shielding lead isotopes(A=206,207 and 208) capture background neutrons become
exicited isotopes 207Pb*,208Pb* and 209Pb* and contributes γ-BK between 2~3MeV.
They and their escapped peaks will mimic the signals of E2β=2039keV
and 63 Cu(n,α)60Co, 2 γ from 60Co will contribute BK to the sgnals.
§3.2
BK problems for experiments of the target nuclide 130Te
For 0νββ search eγ BK
Is not able to discrimated
But trace α-BK could be
Problem if 1D only
Target Nuclide be selected
Q>2615keV !!
Qββ=2615keV
§3.2
60Co(1170+1330)
63
has to be avoided BG of the signals of 0νββ evts of 130Te
Cu(n,α)60Co, 2 γ from 60Co will contribute BK to the sgnals.
Cu-shielder has to be store in proper place where is neutron free
And make sure there is no trace of 60Co
§3.2
90% CL
CdWO4
Energy Resol. Much worse than CUORE
§3.2
FWHM ~80keV much worse than 7~9keV from the
Bolometer of CUORE
§3.2
FWHM=7keV for crystals of 5x5x5 and 9keV for one of 3x3x6 cm at 2615keV
Task to be attacked
1. Improvent the energy resollution by using the bolometer like CUORE
2. To suppress the Alpha radiactive trace isotops BK and neutron-BK
NR events could be discriminated by quenched fluo-light signals
3. Find the proper target nuclides:
Qββ-keV ~3000keV
Abun.% as high as possible
Nuclide
116-Cd
82-Se
100-Mo
96-Zr
150-Nd
48-Ca
130-Te
Qββ-keV
2804.7
2995.4
3034.8
3350.0
3367.1
4272
2528.9
Abun.%
7.6
9.2
9.6
2.8
5.6
.187
33.8
§3.3 CdWO4 as a bolometer with116 Cd- target
nuclides to search the rare deday
A Unit of CdWO4-bolometer
CdWO4 and
§3.2
1. Search the neutrino-less double beta decay of Cd-nuclides(1.32x1022/cm3)
0+
1+
0+
∆
-88.715
116Cd
-88.248 -91.521 MeV
116In
116Sn
E2ß=Q2ß=2.806MeV
Signals are larger than max BK 2.615MeV ER -BK free
the nature abundence of 116Cd is 7.6%
§3.3
114Cd
,A=28.8%
1+
0+
∆
-90.014
114Cd
0+
-88.584 -90.565 MeV
114In
114Sn
E2ß=Q2ß=0.55MeV
DB events are not easy to identify from gamma-electron BG events
§3.3
2. Search for Alpha decay of W-nuclides(1.32x1022/cm3)
A%
0.13

176
72
Hf ( 0 )  

( Q   2 . 482 MeV )

178
72
Hf ( 0 )  

( Q   1 . 787 MeV )
W (0 )
180
74
W (0 )
26.3
182
74
14.3
183
74
W(
30.7
184
74
28.6
186
74
1

)
2
179
72
Hf (
9

)
2
( Q   2 . 356 MeV )

180
72
Hf ( 0 )  

( Q   1 . 682 MeV )

182
72
Hf ( 0 )  

( Q   0 . 998 MeV )
W (0 )
W (0 )
According to Q,the life time were longer than 1019y
and event rate were about 2~3/day. cc
§ 3.3 Technical issues to be attacked
1. Search for new radio-pure scintillation crystals with proper target nuclides
(Qββ and Abundence)— Collab.with SIC and IOPA
Nuclide
116-Cd
82-Se
100-Mo
96-Zr
150-Nd
48-Ca
130-Te
Qββ-keV
2804.7
2995.4
3034.8
3350.0
3367.1
4272
2528.9
Abun.%
7.6
9.2
9.6
2.8
5.6
.187
33.8
2. Thermometers 0f TES (Zhou Xingxiang) and NTD sensors Collab.with IMPL
3. Cryogenic) system(Guo Guoping –Lab.of Quantum Communication USTC)
§3.3
§3.3
不需要液氦的10 mK低温系统。
样品室240X240 mm的样品室,
可以集成复杂的实验装置,
10mK base Temp.
200 and 400   @100
3   @10
Excellent Temp. stability from10mK to 30K
Triton Dilution Refrigerator
17th核电子学和核探测技术学术年会,
兰州,许咨宗
自然科学基金:11275199 基于声子探测的低温粒子探测器
谢谢!
§3.3
EXO200
§3.3
§3.3
KamLAND-Zen
§3.3
§3.3
GERDA
CRESST@ GRAN SASSO/ Italy
Target 33 modules with both light and heat measurement, reaching up to 10
The system is readout by a 66- channels of SQUID system,2 channels for eac
CaWO4 sizes:∅40xh40
17th核电子学和核探测技术学术年会,
N.MIRABOLFATHI , arXiv1308.0044v1
31 Jul.2013
兰州,许咨宗
N.MIRABOLFATHI , arXiv1308.0044v1 31 Jul.2013
17th核电子学和核探测技术学术年会,
兰州,许咨宗
N.MIRABOLFATHI , arXiv1308.0044v1 31 Jul.2013
17th核电子学和核探测技术学术年会,
兰州,许咨宗
Pictures I
Photon

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