1. 2nd International Workshop on Double Beta Decay Search@KRISS
Tune MC with data and Background estimation due to isotopes in PMT glass
S. Myung (SNU)
2nd International Workshop on Double Beta Decay

2. 2nd International Workshop on Double Beta Decay Search@KRISS
Contents
Tune mc with Ruslan’s
Apply to one of DBD scheme
Get energy resolution for gamma
Quenching for alpha(
Use Decay0
Simulate PMT originated 238U/232Th background for different length of light guide
a/b= Ea (MeV) , A.N. Annenkov et al.
2nd International Workshop on Double Beta Decay

3. Detector installation - Ruslan
Teflon wrapping
Mineral Oil
2nd International Workshop on Double Beta Decay

4. 2nd International Workshop on Double Beta Decay Search@KRISS

5. 2nd International Workshop on Double Beta Decay Search@KRISS
DATA
Mean: 348
Sigma:
FWHM: 13.6% MC
Mean: 347
Sigma: 19.97
FWHM: 13.5%
2nd International Workshop on Double Beta Decay

6. 2nd International Workshop on Double Beta Decay Search@KRISS
MC Parameters:
ScintillationYield=742/MeV (CMO)
StandardEM
hadronPhysics: not selected (option),
with QGSP_BERT, Tl208 in 1s sigmal region up by 6%
Bi “ %
Intensity
CMO Emission Spectrum
V.B. Mikhailik et al.(2005)
Absorption Length: 250cm
Absorption Length: 50 cm
2nd International Workshop on Double Beta Decay

7. 2nd International Workshop on Double Beta Decay Search@KRISS
Test with DBD scheme
Passive light guide
PMT+PhotoCathode
CMO
Active light guide
scintillator
Idea/designed by
Barabanov, Khanbekov and Polozov
CMO: f5cm x 5cm, 40Ca100MoO4
ActiveLightGuide : f5cm x (5cm,10cm,15cm) PMMA, PLS
Plastic Scintillator : f15cm x 20cm
PassiveLightGuide : f15cm x 5cm, PMMA
Scintillator and crystals: wrapped by teflon
Air gap between crystal and Scintillator: 5mm
Thickness of glass/cathode: 0.5 mm
2nd International Workshop on Double Beta Decay

8. 2nd International Workshop on Double Beta Decay Search@KRISS
E_g=661.7 (keV) (Deday0) keV Light Guide:10cm
Nhit1
Nhit1:
Nhit2
2nd International Workshop on Double Beta Decay

9. 2nd International Workshop on Double Beta Decay Search@KRISS
10cm
E_g=661.7 (keV)
N(mean)=
Sigma=
FWHM= /- 3.6(%) / /-0.09
efficiency=90%
3s energy cut
nhit_cat2<50
2nd International Workshop on Double Beta Decay

10. 2nd International Workshop on Double Beta Decay Search@KRISS
Linearity Energy Resolution
s/E=2.0/sqrt(E)
s/E=1.8/sqrt(E)
s/E=1.98/sqrt(E)
10cm
5cm cm
2nd International Workshop on Double Beta Decay

11. 2nd International Workshop on Double Beta Decay Search@KRISS
5cm cm cm
2nd International Workshop on Double Beta Decay

12. Background due to 238U/232Th isotopes in PMT Glass
Generate isotopes at the middle plane of PMT Glass
Mass of PMT=0.03 kg
Quartz
<5 ppb
by ET Enterprise
2nd International Workshop on Double Beta Decay

13. 2nd International Workshop on Double Beta Decay Search@KRISS
238U/232Th Decay chain
Merge !!
U238 Chain
2nd International Workshop on Double Beta Decay

14. 2nd International Workshop on Double Beta Decay Search@KRISS
PLG 10cm
Eexp=1..34
Edep=1.42
Eexp=1.18
Edep=1.24
Ea=5.5MeV
Ea=6.0MeV
Edep in CMO
E from nhit_cat1
2% a-decay
3000 keV
Eexp=1.97
Edep=2.02
Ea=7.7MeV
2nd International Workshop on Double Beta Decay

15. 2nd International Workshop on Double Beta Decay Search@KRISS
232Th
PLG 10cm
Edep in CMO
E from nhit_cat1
Bi212
35% a-decay
65% b-decay
(Q=2254)
Ea=8.8MeV
Eexp=2.4
Edep=2.5
2nd International Workshop on Double Beta Decay

16. 2nd International Workshop on Double Beta Decay Search@KRISS
U238 chain: Bi214 decay
5cm
PLG 5cm PMT
Edep in CMO
E from nhit_cat1
10cm
15cm
2nd International Workshop on Double Beta Decay

17. 2nd International Workshop on Double Beta Decay Search@KRISS
232Th
241 keV g
84 keV g
5cm
Edep in CMO
E from nhit_cat1
550 keV g
10cm
15cm
1s=
2nd International Workshop on Double Beta Decay

18. 2nd International Workshop on Double Beta Decay Search@KRISS
U238-chain:
contamination level: 5ppb (0.002 Bq)
For one event in 3s energy range (5cm only)
Nexp/year= 0.4
Nexp/year/kg=0.9
(pmt glass=0.03kg, CMO=0.44 kg)
( keV ~ 9%)
2nd International Workshop on Double Beta Decay

19. 2nd International Workshop on Double Beta Decay Search@KRISS
Th232-chain:
contamination level: 5ppb (0.6mBq)
keV ~ 9%
--- length of light-guide : 5 cm
3s s N_208Tl/year = N_208Tl/year/kg = N_208Tl/year/kg/kev =
--- length of light-guide : 10 cm N_208Tl/year = N_208Tl/year/kg = N_208Tl/year/kg/kev =
--- length of light-guide : 15 cm N_208Tl/year = N_208Tl/year/kg = N_208Tl/year/kg/kev =
N_208Tl/year/kg
2nd International Workshop on Double Beta Decay

20. With active light guide: Plastic scintillator
Assume we can veto signals from active light guide(ALG)
In geant4, remove optical photon which is generated in ALG
2nd International Workshop on Double Beta Decay

21. 2nd International Workshop on Double Beta Decay Search@KRISS
10cm Plastic Scintillator
Eg= (keV)
2nd International Workshop on Double Beta Decay

22. 2nd International Workshop on Double Beta Decay Search@KRISS
Tl208
With Edep by ALG<10keV
3s: 41->20
1s: 2->1
--- length of light-guide : 10 cm
3s s N_208Tl/year =
N_208Tl/year/kg = N_208Tl/year/kg/kev =
2nd International Workshop on Double Beta Decay

23. 2nd International Workshop on Double Beta Decay Search@KRISS
Summary- 1
With untra-low background quartz window PMT (<5 ppb background)
Number of expected background due to
214Bi <0.9/yr/kg for 3s range and 5cm light guide
208 Tl =3.0(3s), 0.5(1s) /yr/kg for 10cm light guide
With veto by active light guide,
The number of background is reduced by half.
–need more statistics
Next: Simulate for a quartz light guide
2nd International Workshop on Double Beta Decay

24. 2nd International Workshop on Double Beta Decay Search@KRISS
Plan for simulation:
Finalize detector simulation for the experiment with 300g CMO
Modify JILee MC or others if available
Kobychev
JILee
Internal background of CMO: learn from KIMS
2nd International Workshop on Double Beta Decay

25. Internal background: KIMSP
Rn220
56.7 +/- 3 s
Po216
0.143+/ s
Energy of alphas: Det6
2nd International Workshop on Double Beta Decay

26. 2nd International Workshop on Double Beta Decay Search@KRISS
KIMS
2nd International Workshop on Double Beta Decay

27. 2nd International Workshop on Double Beta Decay Search@KRISS
summary
Collect simulation results and build fisrt version of AMORE detector with full geometry
Internal background study
Start to think about simulation with cryojenic detector
2nd International Workshop on Double Beta Decay