a study on camoo4 crystal coupled with laapd for neutrinoless double beta decay
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A study on CaMoO4 crystal coupled with LAAPD
for neutrinoless double beta decay
Sejong UniversityJung il LEE
LEE J.I., BHANG H.C.1, CHOI J.H.1, KIM S.C.1, KIM S.K.1, KIM S.Y.1, KWAK J.W.1, LEE J.H.1, LEE H.S.1, LEE J.1, MYUNG S.S.1, YANG H.Y.1, KIM Y.D., MOON S.H., KIM H.J.2, SO J.H.2, YANG S.C.2, HWANG M.J.3, KWON Y.J.3, HANH I.H.4, PARK I.H.4, LEE M.H.5, SEO E.S.5,
LI J.6, ZHU J.J.7, HE D.7, YUE Q.7
Sejong University,Physics. 1Seoul National University,Physics. 2Kyungpook National University,Physics. 3Yonsei University,Physics. 4Ewha Womans University,Physics. 5Univ. of Maryland. 6IHEP. 7Tsinghua University.
• Introduction• Double Beta Decay (DBD)?• For CaMoO4 crystal & LAAPD • Results of experiment for LAAPD• CaMoO4 data result • Results
Outline
DBD(Double Beta Decay)
2+
0+
0+
0+
2-
Ge76
As76
Se76
EndpointEnergy
(2): Allowed and observed 2nd order weak process.
(0): requires massive Majorana neutrinos.
e
e
e
e
n
n n
np
p
p
p
2222 epn
에너지
Event수 20
Motivation - Why CaMoO4 Crystal ?• Mo 를 포함하는 Active detector 중 상온에서 가장 섬광효율이 높다 .
Lightoutput increases by factor 3.5 @ 150K
Mikhrin et al. NIM 486, 295(2002)
상온에서 CsI(tl) 의 20% light increase at lower temperature CaMoO4 may be very good crystal for DBD
• High quantum efficiency : High quantum efficiency : 약 약 90% @ 90% @ 500nm 500nm PMTPMT 의 경우 약 의 경우 약 10-25%10-25%
Solovov(1999)5mm LAAPD
LAAPDLAAPD 는 는 -- 200200 도에서도 도에서도 작동작동 .. Significantly reduced dark current Higher gains can be achieved Noise level can be reduced
CaMoO4 + LAAPD can be excellent detector for DBD
Previous Results of LAAPD
• CsI(Tl) + 16mm LAAPD • 4.8%FWHM for 662 keV• LAAPD has better resolution than PMT due to high Q.E.
M. Moszynski
Room temperature measurements
5.9 keV X-ray9.3% FWHM =4.0% RMS
Source
ORTEC PREAMPLIFIER 142AH
(High Voltage 용 )POWER SUPPLY(HV)
ORTEC
AMPLIFIER 571
Crystal
LAAPD
Output (Room Temperature)
Output (Low Temperature)
Experimental Setup
CaMoO4, CsI R&D Crystals
14.3x15x13.7mm14.3x15x13.7mm-Crystal bank at Pusan National University
-CsI & CamoO4 Russia Crystal ~10x10x10mmx10x10mm
• 투명 , nonhydroscopic• 밀도 : 4.4 (CaMoO4)
CsI(Tl) 과 CaMoO4 의 상온에서의 비교
2.7%(6.3FWHM)
Light output;CaMoO4/CsI=6.3% Mikhrin 데이터보다 CaMoO4 의 scintillation efficiency 가 낮다 .
3 인치 PMT with 137Cs 소스 (662 keV)
CsI(Tl) CaMoO4
Charge(arb. Unit)
9.9%(23.27FWHM)
Charge(arb. Unit)
Test on CsI(Tl)+LAAPD @Room temperature
•HV ; +1750
•Source ; 137Cs
•Threshold ; 36mV
•Size ; 10*10*10mm
Compton edge
Channel number
# o
f even
ts
Back scatters
(6%FWHM)
We confirmed good resolution of CsII(Tl)+LAAPD detector at room temperature
CaMoO4+LAAPD @LowTemp
• Decay time ~ 100 s @ -150 oC • But shaping time of AMP is limited by 10 sAnalyzed PreAmplifier Signal directly.• Source ; Cs-137• Temp ; -159.2 oC ± 0.1
P0 = amplitude, P2=decay time, P4=rising time, P5 = backgroundP6= start time
Micro sec
mV
p4
p6
p0
p2
p5
5/)(
2
/)(
2
0 4626 exp1
exp ppp
pf pptpptfit
0 의의의의의의의 3 MeV 에너지 영역에서는 약 5.3%(FWHM) 의 energy resolution이 예상된다 .
FWHM%3.5RMS%24.23043
662RMS%7.4)expected(0
keV
keV
resolutionCompton edge
•4.7%(11FWHM) Resolution with CaMoO4 crystal in low temperature(-159°C)
(11FWHM)
• 10kg 100Mo enriched(95%) CaMoO4 (~100kg natural)
• 6% FWHM @ 3MeV energyEstimated background counts in 1 year in 1 FWHM energy region•48Ca double beta decay(T1/2=4X1019 y)
• 100Mo double beta decay(T1/2=8X1018 y)
T(1/2) > 3.3X1024 year Current best limit: 5x1022 years (Ejiri)
3.5x1023 years(NEMO)
Sensitivities of CaMoO4
)2(48 Ca
)2(100 Mo
)0(100 Mo
Conclusion & Future Plan
• Studies on temperature dependencies• Studies on PbMoO4 with LAAPD• realistic resolution test with 208Tl(2.6MeV) Source
100mm
30mmCaMoO4(310g)
• Studied CaMoO4 Crystal + LAAPD detector at room temperature & low temperature.
• Obtained 4.7% RMS resolution for 662 keV, and expect 5.3% FWHM resolution for 0 Signal
Why CaMoO4 Crystal ?
Mo-100 2nuMo-100 2nu
Ca-48 2nuCa-48 2nu
Tl-208Tl-208
Bi-214Bi-214Signal (m=0.3eV)Signal (m=0.3eV)
• Light output :20% of CsI(tl)• light increase with lower temperature•Decay time :16.6+-0.1 micro sec• Pulse shape discrimination capability
Various Backgrounds and signal estimation with 20kg of CaMoO4 with 5 years data taking (GEANT4)
Future plan & Results
• Remake of Low temp installation• Test of PbMoO4 crystal• DBD experiment start (if possible)
Thank you !!!!!!!!!!!
Mikhrin et al. NIM 486, 295(2002)Studies on Molybdates, CaMoO4, SrMoO4
Emission spectrum
20% of CsI(Tl) @ 300KDecay time 16 s
Lightoutput increases by factor 3.5 @ 150K
DBD(Double Beta Decay)
2+
0+
0+
0+
2-
Ge76
As76
Se76
EndpointEnergy
(2): Allowed and observed 2nd order weak process.
(0): requires massive Majorana neutrinos.
e
e
e
e
n
n n
np
p
p
p
2222 epn
RbCs 3 인치 PMT data(room Temp)
3.3%Am-241(5.6MeV)
19.3%Am-241(5.6MeV)
5.4%(FWHM)Cs-137(662KeV)
5.2%Cs-137(662KeV)
Light output;CaMoO4/CsI=5.4%
Light output;CaMoO4/CsI=5.9%•Inconsistent with “Mikhrin”
Russia crystal
Pusan Univ. crystal
Channel number
# o
f even
ts
LAAPD-Room temperature data
HV ; +1750Source ; Fe-55Threshold 20mVw/o Crystal3.5eV/1e-h pair
Statistically, expected e-h pair from 5.9 keV3.5 eV/ e-h pair in Silicon5900/3.5 ~1700 e-h pair2.4% RMSNoise contribution is dominant
selectroniclaapd
lstatistica
noise
stat
noisestatmeasured
:
:2
2
222
20.3%FWHM
CsI vs CaMoO4 at LAAPD 2
CsI 10xx10xx10mm
CaMoO4 10x10x10mmx10x10mm
# o
f ee
ven
ts
# o
f ee
ven
ts
Mean;2.715
Mean;0.0509
•Light output ; 1.9%•Am-241 Source(5.6MeV)
Channel number
Channel number
• 10kg 100Mo enriched(95%) CaMoO4 (~100kg natural)6% FWHM @ 3MeV energyEstimated background counts in 1 year in 1 FWHM energy
region1. 48Ca double beta decay(4X1019 y) 32.02. 100Mo double beta decay(8X1018 y) 7.43. Background assuming Solotvina exp(0.03
/kg/keV/year) 109.2 (conservative)Total 148.7 counts/ year T(1/2) > 3.3X1024 year
Current best limit: 5x1022 years (Ejiri)3.5x1023 years(NEMO)
Sensitivities of CaMoO4
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