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A study on CaMoO4 crystal coupled with LAAPD for neutrinoless double beta decay

A study on CaMoO4 crystal coupled with LAAPD for neutrinoless double beta decay. Sejong University Jung il LEE

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A study on CaMoO4 crystal coupled with LAAPD for neutrinoless double beta decay

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  1. A study on CaMoO4 crystal coupled with LAAPD for neutrinoless double beta decay Sejong University Jung 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.

  2. Outline • Introduction • Double Beta Decay (DBD)? • For CaMoO4 crystal & LAAPD • Results of experiment for LAAPD • CaMoO4 data result • Results

  3. DBD(Double Beta Decay) Endpoint Energy bb(2n): Allowed and observed 2nd order weak process. bb(0n): requires massive Majorana neutrinos.

  4. Motivation - Why CaMoO4 Crystal ? • Mo를 포함하는 Active detector중 상온에서 가장 섬광효율이 높다. • 상온에서 CsI(tl)의 20% • light increase at lower temperature •  CaMoO4 may be very good crystal for DBD Mikhrin et al. NIM 486, 295(2002) Lightoutput increases by factor 3.5 @ 150K

  5. Why LAAPD(Large Area Avalanche Photodiode) ? Advanced Photonics사의 16mm 직경의 LAAPD (world largest)

  6. 5mm LAAPD Solovov(1999) • High quantum efficiency : 약 90% @ 500nm • PMT의 경우 약 10-25% LAAPD는 -200도에서도 작동. Significantly reduced dark current Higher gains can be achieved Noise level can be reduced CaMoO4 + LAAPD can be excellent detector for DBD

  7. Previous Results of LAAPD Room temperature measurements • CsI(Tl) + 16mm LAAPD • 4.8%FWHM for 662 keV • LAAPD has better resolution than PMT due to high Q.E. 5.9 keV X-ray 9.3% FWHM =4.0% RMS M. Moszynski

  8. Experimental Setup ORTEC PREAMPLIFIER 142AH (High Voltage 용 ) Crystal POWER SUPPLY(HV) LAAPD Source Output (Low Temperature) Output (Room Temperature) ORTEC AMPLIFIER 571

  9. CaMoO4, CsI R&D Crystals • 투명, nonhydroscopic • 밀도 : 4.4 (CaMoO4) -CsI & CamoO4 Russia Crystal ~10x10x10mm -Crystal bank at Pusan National University 14.3x15x13.7mm

  10. CsI(Tl) 과 CaMoO4 의 상온에서의 비교 3인치 PMT with 137Cs 소스 (662 keV) CsI(Tl) CaMoO4 2.7%(6.3FWHM) 9.9%(23.27FWHM) Charge(arb. Unit) Charge(arb. Unit) Light output; CaMoO4/CsI=6.3%  Mikhrin 데이터보다 CaMoO4의 scintillation efficiency 가 낮다.

  11. # of events (6%FWHM) Back scatters Comptonedge Channel number Test on CsI(Tl)+LAAPD @Room temperature • HV ; +1750 • Source ; 137Cs • Threshold ; 36mV • Size ; 10*10*10mm We confirmed good resolution of CsII(Tl)+LAAPD detector at room temperature

  12. mV p2 p0 p4 p5 Micro sec p6 CaMoO4+LAAPD @LowTemp • Decay time ~ 100 ms @ -150 oC • But shaping time of AMP is limited by 10 ms • Analyzed PreAmplifier Signal directly. • Source ; Cs-137 • Temp ; -159.2 oC ± 0.1 P0 =amplitude, P2=decay time, P4=rising time, P5 = background P6= start time

  13. Compton edge resolution • 4.7%(11FWHM) Resolution with CaMoO4 crystal in low temperature(-159°C) 0nbb의 시그널이 있는3 MeV 에너지 영역에서는 약 5.3%(FWHM)의 energy resolution이 예상된다. (11FWHM)

  14. Sensitivities of CaMoO4 • 10kg 100Mo enriched(95%) CaMoO4 (~100kg natural) • 6% FWHM @ 3MeV energy Estimated background counts in 1 year in 1 FWHM energy region • 48Ca double beta decay(T1/2=4X1019y) • 100Mo double beta decay(T1/2=8X1018 y)  T(1/2) > 3.3X1024 year Current best limit: 5x1022 years (Ejiri) 3.5x1023 years(NEMO)

  15. 100mm 30mm CaMoO4(310g) Conclusion & Future Plan • 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 0nbb Signal • Studies on temperature dependencies • Studies on PbMoO4 with LAAPD • realistic resolution test with 208Tl(2.6MeV) Source

  16. Mo-100 2nu Ca-48 2nu Signal (m=0.3eV) Bi-214 Tl-208 Why CaMoO4 Crystal ? • 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)

  17. Future plan & Results • Remake of Low temp installation • Test of PbMoO4 crystal • DBD experiment start (if possible) Thank you !!!!!!!!!!!

  18. POWER SUPPLY(HV) Source LAAPD Crystal ORTEC PREAMPLIFIER 142AH ORTEC AMPLIFIER 571 Set up

  19. Mikhrin et al. NIM 486, 295(2002) Studies on Molybdates, CaMoO4, SrMoO4 20% of CsI(Tl) @ 300K Decay time 16 ms Emission spectrum Lightoutput increases by factor 3.5 @ 150K

  20. DBD(Double Beta Decay) Endpoint Energy bb(2n): Allowed and observed 2nd order weak process. bb(0n): requires massive Majorana neutrinos.

  21. According to Advanced Photonix

  22. 3.3% Am-241(5.6MeV) Pusan Univ. crystal 19.3% Am-241(5.6MeV) # of events Russia crystal Channel number RbCs 3인치 PMT data(room Temp) Light output; CaMoO4/CsI=5.4% 5.2% Cs-137(662KeV) 5.4%(FWHM) Cs-137(662KeV) • Light output; • CaMoO4/CsI=5.9% • Inconsistent with “Mikhrin”

  23. LAAPD-Room temperature data HV ; +1750 Source ; Fe-55 Threshold 20mV w/o Crystal 3.5eV/1e-h pair 20.3%FWHM • Statistically, expected e-h pair from 5.9 keV • 3.5 eV/ e-h pair in Silicon • 5900/3.5 ~1700 e-h pair • 2.4% RMS • Noise contribution is dominant

  24. (88KeV) CsI & CamoO4 at LAAPD 1 • LAAPD • Room Temp • Source ; Cd-109 CsI crystal ? CamoO4 Crystal

  25. CsI vs CaMoO4 at LAAPD 2 • Light output ; 1.9% • Am-241 Source(5.6MeV) # of events CsI 10x10x10mm Mean;2.715 Channel number CaMoO4 10x10x10mm # of events Mean;0.0509 Channel number

  26. Sensitivities of CaMoO4 • 10kg 100Mo enriched(95%) CaMoO4 (~100kg natural) 6% FWHM @ 3MeV energy Estimated background counts in 1 year in 1 FWHM energy region • 48Ca double beta decay(4X1019y)  32.0 • 100Mo double beta decay(8X1018 y)  7.4 • 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)

  27. Sample 2(20x20x10mm) 0.4 pe/keV 14.4% FWHM expected 17.3% FWHM measured.

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