Transcript Slide 1

Characterization of Large
CaMoO4 crystals for 0n bb search
2nd
Presented by H.J.Kim
(KyungPook National U.)
2007/11/24
Korea-China Joint workshop
Double beta work status
• Sn-124 excited state, Zn-64 study was
published in Nuclear Physics A 2007.
 0-n bb for Sn-124 with LSC physics draft is
in progress (NIMA published in 2007)
• CaMoO4 study is on going :
• Mo-92: EC/b+ study in 4p CsI(tl) shielding
+CaMoO4 background test (J.I.Lee’s talk)
• SrCl2 : EC/b+ study in 4p CsI(tl) (J.So)
• CeBr3 crystal development for EC/b+, b+b+,
study (Gulrooh’s talk)
• Sn-112 resonant 0n ECEC study with HPGe
Korea-China Workshop 2007,
H.J.Kim
2.2 cm
CaMoO4 Scintillation crystals
Korea(2004)
Ukraina(2006)
Russia(2006)
Russia(2007), ISTC Project
Sino-Korean Workshop 2006,
H.J.Kim
History
• CaMoO4 crystal R&D in very fast progress
1) 2002 : Idea and try to grow CMO in Korea
2) 2003 : Discussion with V.Kornokov
=> Send test CMO (better quality)
3) 2004 : CMO characterizations and Conference
presentation
Extended idea of XMoO4, low temp. CaMoO4
4) 2005-2007 : Large CMO with ISTC
5) 2006
: Discussion with F. Fanevich
=> CMO by Lviv and collaborative effort
6) 2007 : CMO R&D in low temp. started by SNU
group
7) ……….
H.J.Kim
Crystal used for test
2.2 cm
Russia
S1
22x22x30mm
S0
10x10x10mm
Large (L1)
22x22x125
XL1, 2
30x30x210
f38x20 mm
Ukraine
UK2
UK3
Korea-China Workshop 2007,
H.J.Kim
Clustering method with 400 Mhz FADC
The same method with Darkmatter Search
Total 42 ms window with 34 ms pulse window
Korea-China Workshop 2007,
H.J.Kim
# of Photoelectron/keV
& Absolute light yield
# of PE with 60keV gamma
CdWo4
S1
UK2
UK2
Korea-China Workshop 2007,
H.J.Kim
:197+-19
:28+-8
:37.5+-8
:41.9+-10
Number of photoelectron from 60keV g
# of photoelecton from Am-241
Crystals tested
0.6-0.7PE/keV : Ukraine
0.4-6PE/keV : Russia
0.5PE/keV : Korea
* The size of crystals are
different
0.6 PE/keV => 6% FWHM at 3MeV (theoretical limit)
Korea-China Workshop 2007,
H.J.Kim
CaMoO4 small absolute light yield
CsI(Tl) reference test
• Cs-137 source
• Gain:20
• Shaping time:4us
• HV:1800V
• Peak:1597±34.4
• Pedestal:33±10
• Resolution(FWHM):
4.9%
• e-h pair = 37000.
• NP = 37000/0.8/0.9 =
51000
CaMoO4 S0 test
• Na-22 source
• Gain:100
• peak time:12us
• HV:1800V
• Peak:520±116
• e-h of CsI(Tl): 8.6±1%
• 4300±500ph/MeV
• Assume 15% QE,90% eff
0.6 ± 0.1 PE/keV
 Need more study
* Tested with LLAPD (Details by M.J.Kim)
Attenuation Length&
Relative light output with
S1 & XL1, XL2
Korea-China Workshop 2007,
H.J.Kim
Large size CaMoO4 test
2.2 cm
- using two 3" PMT’s and attached at both end
faces of CaMoO4 crystal.
- made small holes of few millimeter diameter at
every 2cm distance in the teflon along the length
wise direction of the crystal.
PMT1
PMT2
Comparison between S1 and L1
CaMoO4
Light yield of Big CMO/ Small CMO is 90%
Energy spectrum of Am-241
-
Placed the Am-241 radioactive source at every 2cm mark
Red= 2cm
Green= 4cm
Blue= 6cm
Pink= 8cm
Black= 10cm
Attenuation Length
PMT1
PMT2
PMT1+PMT2
26000
24000
22000
Mean
20000
18000
16000
14000
12000
10000
0
2.0x10
0
4.0x10
0
6.0x10
0
8.0x10
Distance(cm)
Attenuation Length = ~ 30 cm
1
1.0x10
Larger (XL1, XL2) CaMoO4 test
- XL1,XL2 crystals were used for test.
- using one 3" PMT (green extended) and one 2"
PMT (bi-alkali) of CaMoO4 crystal.
- made small holes of few millimeter diameter at
every 3cm distance
a test with S1 & XL1, XL2
XL1 : ~70% of S1, XL2 : ~80% of S2
3” PMT side with Cs-137
H.J.Kim
L1-CMO
PMT1
PMT2
PMT1+PMT2
22000
20000
Light output
18000
16000
14000
12000
10000
8000
0
2
4
6
8
10
12
Distance
H.J.Kim
14
16
18
20
Mean
L2-CMO
2"PMT
3"PMT
sum
27000
26000
25000
24000
23000
22000
21000
20000
19000
18000
17000
16000
15000
14000
13000
12000
11000
10000
9000
0
2
4
6
8
10
12
Distancs(cm)
H.J.Kim
14
16
18
20
Resoultion & light output comparison
with S1 and UK2,UK3
Korea-China Workshop 2007,
H.J.Kim
Checking energy resolution with CdWO4
Energy resolution of 9%
H.J.Kim
Cs137 source with CMOs and CdWo4
H.J.Kim
Cs-137 with S1 and UK2, UK3
Relative light yield ; 1.2 : 1.9 : 2.0
H.J.Kim
Different fitting, different results
• The best way is subtract background from data and
fold MC data with data with Gausian fit only
H.J.Kim
S1 with Gaussian+Exp
18% FWHM
H.J.Kim
Mean time distribution of CMOs
H.J.Kim
Summary
• Different size of CMO crystals from Russia
(ISTC project) and Ukraine are being tested
• # of photoelectron/keV, absolute light yield
and attenuation length are measured
• Relative light output and energy resolution
were compared.
H.J.Kim
Work list before experiment
• Resolution and light yield issue
->Different crystal results need to be resolved
Test with the same size of LU3 and XL1
Improve light output…
->Further study of LAAPD : LAAPD or PMT?
-> How low temperature is necessary?
-> Size of CMO optimization
• Internal Background issue
-> measurement UK3 (results) XL (soon…)
=> Shielding optimization for VETO
• Enriched 100Mo, purification, growing issues
• Low temp Det.,
• XMoo4 (X->?)
H.J.Kim
Backgrounds and signal for 20kg of CaMoO4 with 5
years data taking (GEANT4)
Sensitivity
10kg (100Mo)
5% FWHM resolution
0.05 mBq/kg for 208Tl, 214Bi
5 years  7.1x1024 y (90% CL)
( 0.18~0.71 meV)
Mo-100 2n
Ca-48 2n
Signal (m=0.4eV)
Bi-214
Tl-208
10s significance
•Current best limit on 100Mo :
4.6x1023 by NEMO3 with 6.9kg 100Mo
•Claim by Klapdor-Kleingrothaus et al.
 ~ 400 meV
 Assuming optimistic theoretical value
H.J.Kim
• Thank you
H.J.Kim
New Crystal for Am-241
Mean of det00 (2” PMT)
Mean of det01(3” PMT)
Distance
1
15390
10960
3
6
9
12
15
18
14880
14740
14630
14390
13880
15120
10950
10990
10930
10610
11398
9494
Old Crystal for Am-241
Distance
1
3
6
9
12
15
18
Mean of det00(2” PMT)
Mean of det01(3” PMT)
12810
11280
10910
10890
10530
9663
11790
9370
9785
9784
9695
9757
10460
8416
H.J.Kim
H.J.Kim
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