Development of CaMoO 4 Scintillation Crystals for the 0-  decay search 1.Introduction 2.CaMoO4 Crystal R&D 3.YangYang underground laboratory for KIMS 4.Internal background measurement and Sensitivity 5.Prospect H.J.Kim (KyungPook National U.) for KIMS Joint Meeting of Pacific Region Particle Physics Communities Hawaii, Nov 1/2006

DPF 2006, H.J.Kim Importance  of  processes (A,Z) (A,Z+1) (A,Z+2) (A,Z) -> (A,Z+2) + 2  +2 (A,Z) -> (A,Z+2) + 2  +2 (A,Z) -> (A,Z+2) + 2  

DPF 2006, H.J.Kim 1/T 0 1/2 = G 0 (E 0,Z) |M 0 | 2 2, 1/T 0 1/2 = G 0 (E 0,Z) |M 0 | 2 2, G 0 (E 0,Z) : phase space factor ( ~ Q  5 ), G 0 (E 0,Z) : phase space factor ( ~ Q  5 ), M 0 -Nuclear Matrix Element, hard to calculateM 0 -Nuclear Matrix Element, hard to calculate Uncertain to factor 2-10, isotope dependent Motivation to measure several isotopes Theory issues Experimental limits : Experimental limits : T 0 1/2 = 4.17x10 26    (a/A)   (M T/B R) 90% C.L. T 0 1/2 = 4.17x10 26    (a/A)   (M T/B R) 90% C.L. B = background index in cts/(keV kg y) B = background index in cts/(keV kg y) R = FWHM energy resolution at Q  in keV R = FWHM energy resolution at Q  in keV M = mass of detector in kg, A = mass number M = mass of detector in kg, A = mass number  = detection efficiency at Q , a =  isotope fraction,  = detection efficiency at Q , a =  isotope fraction, m = mass of detector in kg t = measured time in years m = mass of detector in kg t = measured time in years

Experimental method Two classes of approach to the experiment:Two classes of approach to the experiment: –Direct Method Ionization detectors : HPGe, TPCIonization detectors : HPGe, TPC Scintillation detectors : CdWo4, CaF2, CaMoO4,Scintillation detectors : CdWo4, CaF2, CaMoO4, Bolometer detectors : TeO2Bolometer detectors : TeO2 –Indirect Method Tracking detectors : foil +tracking+scinTracking detectors : foil +tracking+scin Mo with 6% FWHM Mo with 6% FWHM Experimental signature: 2e -,  t~0 ns,  E e =Q  Q   few MeV

2005/09/20 SCINT2005, H.J.Kim The Best 0 -DBD results with different nuclei 1.8 * (eV) 6.0 > 1.8  Ca Ogawa I. et al., submitted 2002 Belli et al. Experiment < > 7  Xe Range T 1/2 0  (y)Isotope Bernatowicz et al Zdenko et al Ejiri et al. 2004* Aalseth et al 2002 Klapdor-Kleingrothaus et al Mi DBD 2002 < > 2.1  Te < > 7.7  Te geo < > 1.3  Cd < > 5.5  Mo < > 1.57  < > 1.9  Ge 100 Mo : 4.6x10 23 years by NEMO3, Mo : 4.6x10 23 years by NEMO3, 2006 Klapdor group claimed positive signal atKlapdor group claimed positive signal at M ~400 mV M ~400 mV

Projected/proposed ExperimentNucleusDetector T 0 ν (y) T 0 ν (y) eV eV CUORE 130 Te.77 t of TeO 2 bolometers (nat) 7 x EXO 136 Xe 10 t Xe TPC + Ba tagging 1 x Gertha 76 Ge 1 t Ge diodes in LN 1 x Majorana 76 Ge 1 t Ge diodes 4 x MOON 100 Mo 34 t nat.Mo sheets/plastic sc. 1 x DCBA 150 Nd 20 kg Nd-tracking 2 x CAMEO 116 Cd 1 t CdWO 4 in liquid scintillator > COBRA 116 Cd, 130 Te 10 kg of CdTe semiconductors 1 x Candles 48 Ca Tons of CaF 2 in liq. scint. 1 x GSO 116 Cd 2 t Gd 2 SiO 5 :Ce scint in liq scint 2 x Xmass 136 Xe 1 t of liquid Xe 3 x

DPF 2006, H.J.Kim Scintillation Crystals for  (Calorimeter technique)  300g 116 CdWO 4  search by Kiev group; >0.7x10 23 years Enrichment, PSD, active shielding -> successful Enrichment, PSD, active shielding -> successful  CaMoO 4 ; Mo, Ca  search * First recognized by this group * First recognized by this group (H.J.Kim et al, New view in particle physics,Vietnam Aug 2004.) (H.J.Kim et al, New view in particle physics,Vietnam Aug 2004.) * Can be also used for scintillation bolometer * Can be also used for scintillation bolometer  CaF 2  CaF 2 (Eu) (CANDLES)  GSO

DPF 2006, H.J.Kim CaMoO 4 Crystals for R&D 14.3x15x13.7mm (PSU) (PSU) 20x20x20mm 24.8x30x40.8mm 18x18x30mm (Russia) (Russia) 10  x10mm CaMoO4 (Ukraine) (Ukraine)

DPF 2006, H.J.Kim CaMoO 4 Pulse shape with 400MHz FADC 60keV  5.5MeV 

DPF 2006, H.J.Kim CaMoO 4 ( 14.3x15x13.7mm) with  source - Na22(511keV,1.275keV), Cs137(662keV), Co57(120keV),Cd109(88keV)

DPF 2006, H.J.Kim Number of photoelectron from 60keV  # of photoelecton from Am-241 Crystals tested 0.6PE/keV : Ukraine 0.6PE/keV : Russia 0.5PE/keV : Korea * The size of crystals are different 0.6 PE/keV => 6% FWHM at 3MeV

DPF 2006, H.J.Kim Alpha response of CaMoO 4 and PSD E  = 0.2 with 5.5MeV 

Large size CaMoO4 test - using two 3" PMT ’ s and attached at both end faces of CaMoO 4 crystal. -made small holes of few millimeter diameter at every 2cm distance in the teflon along the length wise direction of the crystal. PMT1 PMT cm 2.2 cm

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 Attenuation Length = ~ 30 cm

DPF 2006, H.J.Kim Large area opto-sensor with high efficiency R&D Silicon Drift sensor Large ared : 5x5cm Noise : a few hundred RMS noise Noise : a few hundred RMS noise High quantum efficiency : 80% High quantum efficiency : 80% (PMT: 15% ) (PMT: 15% ) 4x4 1.5cm Photodiode ->noise problem Large Area avalanche photodiode (1.6cm diameter) Sensor R&D is ongoing at KNU PHOTONICS

DPF 2006, H.J.Kim 5 %(FWHM) energy resolution or better at 3 MeV (0  signal) resolution Compton edge 4.7%(11% FWHM) Resolution with CaMoO4 crystal in low temperature(-159°C) (11% FWHM) LAAPD

DPF 2006, H.J.Kim Environment Parameters in Y2L Depth Minimum 700 m Temperature 20 ~ 25 o C Humidity 35 ~ 60 % Rock contents 238 U less than 0.5 ppm 238 U less than 0.5 ppm 232 Th 5.6 A 2.6 ppm 232 Th 5.6 A 2.6 ppm 40 K 270 A 5% ppm 40 K 270 A 5% ppm Muon flux 2.7 x /cm 2 /s 2.7 x /cm 2 /s Neutron flux 8 x /cm 2 /s 8 x /cm 2 /s 222 Rn in air 1~2 pCi/liter Gneiss (2 Gyr )

DPF 2006, H.J.Kim Liquid scin. 30cm Boliden Lead 15cm : 30t OFHC Cu 10cm : 3t CsI crystal detector

DPF 2006, H.J.Kim CaMoO4 background measurement at Y2L *18x18x35mm CaMoO4 crystal + RbCs PMT Inside KIMS lead shielding * 250Mhz FADC mode with no deadtime 1 month data => Bigger crystal test will be performed in the 4  CsI shielding

DPF 2006, H.J.Kim Backgrounds and signal for 20kg of CaMoO 4 with 5 years data taking (GEANT4) Mo Mo Ca-48 2 Ca-48 2 Tl-208 Bi-214 Signal (m=0.4eV) Sensitivity 10kg ( 100 Mo) 5% FWHM resolution 0.05 mBq/kg for 208 Tl, 214 Bi 5 years  7.1x10 24 y (90% CL) ( 0.18~0.71 meV) Current best limit on 100 Mo : 4.6x10 23 by NEMO3 with 6.9kg 100 Mo Claim by Klapdor-Kleingrothaus et al.  ~ 400 meV  Assuming optimistic theoretical value 10  significance

DPF 2006, H.J.Kim CaMoO 4 (PbMoO 4, SrMoO 4, ZnMoO 4 ) ; Mo-100, 0-  Search 10kg Mo-100 CaMoO 4 : 7.1 x10 24 y (~0.2eV) (present 4.6x10 23 y) 1ton Mo-100 CaMoO 4 : 7 x10 26 y (~0.02eV) (further background 100 reduction assumed)

Conceptual design of experimentxMoO4+Photosensor(30cmx30cm) CsI or PbMoO4(5cm) Low background Pb (15cm) LN2 Cooled Active Muon Veto(LSC), 30cm

DPF 2006, H.J.Kim Summary and Prospect Summary and Prospect  0.6 PE/keV -> 6% FWHM at Q= 3MeV (5% at low temp)  PSD possible, E a/g ratio: 0.2  Currently working on 1) Temperature dependence study with Silicon sensor 2) U,Th reduction of powder, Crystal growing 3) Internal background measurement of CaMoO 4 at Y2L 4) 4) SrMoO4, XMoO4( X= Zn, Ba, Pb etc) R&D  Future Plan : 10kg of Mo-100 enriched CaMoO4 crystals could be installed at YangYang underground Lab in a couple of years. 10kg of Mo-100 enriched CaMoO4 crystals could be installed at YangYang underground Lab in a couple of years. Sensitivity: ~ years by 90% CL with 5 years data taking Sensitivity: ~ years by 90% CL with 5 years data taking

DPF 2006, H.J.Kim Thank you

Energy spectrum of Cs-137 -

Configuration Most outside : 30 cm muon veto LSC 15cm lead 5cm : PbWo4 or PbMoO4 (LN cool case) or CsI(Tl) 30x30x 30 cm crystal ( 100kg) Muon veto LSC : 50x2cm Lead : 20x2cm Crystal veto : 10x2cm DB crystal : 50 cm ( 100cm for 4ton) cm (260cm) -> 3m x 3m x 5m space (z direction 5m : PMT, cables etc) -> 3.5mx 3.5mx 10m space of room will be enough up to 1ton of DB experiment. -> Available at YangYang lab.