Solotvina Underground Laboratory Institute for Nuclear Research (Kiev, Ukraine) http://lpd.kinr.kiev.ua

Solotvina Underground Laboratory was built up in 1984 on the west of Ukraine in Solotvina (Transcarpathian region) NaCl salt mine 430 m underground (1000 m w.e.) The Solotvina Underground Laboratory was build in sodium chloride mine in Transcarpathians region of Ukraine at the depth of 430 m. It corresponds to approximately one thousand meters of water equivalent. Total square  1000 m2

Background conditions Background of CdWO4 scintillator (44 cm)  flux: 1.5103 m-2·d-1 measured by plastic scintillator counter Termal n flux: 310-6 cm-2·s-1 by 3He counter Radon: 30 Bq·m-3 by radon monitor (Honeywell A 9000A 1006) Temperature is 241C independent of season Background of CdWO4 scintillator (44 cm) Kiev Solotvina 1000 m w.e. Solotvina in shield

Background measured by HP Ge detector 165 cm3 Set up with HP Ge Solotvina, 1000 m w.e. 1109 h, in shield Due to low radioactive contamination of the salt, the natural  background in the SUL is 10100 times lower than in other underground laboratories

Experiment to search for 2 decay of 116Cd Kiev-Florence collaboration Plastic active shield CdWO4 20.6 kg Copper 116CdWO4 0.33 kg Plastic light guide Quartz light guide Channel for calibration

Main results of 116Cd  experiment 22 decay of 116Cd was observed Limits on 02 decay of 116Cd T1/20  1.723 yr at 90 % C.L. m  1.7 eV   2.510-8   2.210-6 T1/20M  0.822 yr gM  8.110-5 CAMEO project was proposed PRC 68 (2003) 035501 100 kg of 116CdWO4 scintillators allocated in a large volume of high-pure liquid  PLB 493 (2000) 216; EPJC 19 (2001) 43

Search for 2 decay of 160Gd  T1/20  1.321 yr was performed with the help of Gd2SiO5(Ce) crystal scintillator, 635 g, 13 949 h 2 160Gd Q2 = 1730 keV T1/20  1.321 yr  T1/22  1.919 yr at 90 % C.L. Yad. Fiz. 58 (1995) 195; NPA 694 (2001) 375

 decay of 113Cd was investigated CdWO4 454 g, 433 h ½+ 0 113Cd  9/2+ 0 Q = 316 keV 113In Fourth-forbidden  decay Shape of energy spectrum of fourth-forbidden  decay of 113Cd was measured by CdWO4 scintillator with natural isotopic abundance. As you can see Kurie plot for this beta spectrum is noticeably different from a straight line. Half-life was measured with much better accuracy due to higher (50 to1) ratio of effect to background. T1/2= (7.70.3)1015 yr [ Yad. Fis. 59(1995)5 ] Previous T1/2: (9.31.9)1015 yr [1]; (9.30.5 1)1015 yr [2] [1] J.Inorg.Nucl.Chem. 32(1970)2113; [2] NPB (Proc.Suppl.) 35(1994)394

 decay of 180W was observed 116CdWO4 330 g, 2975 h,  spectrum The indication for the  decay of 180W with a half-life 1.1 by 10 to 18 yr has been observed due to pulse-shape discrimination of events in the cadmium tungsten enriched detector. T1/2= [1.1 (stat)0.3(syst)] 1018 yr +0.8 –0.4 Recently this result was confirmed with CaWO4 as scintillator [Yu.G.Zdesenko et al., NIMA in press] and bolometer [C.Cozzini et al., PRC 70(2004)064606] PRC 67 (2003) 014310

Low radioactivity technique  Sensitive methods to measure radioactive contamination of scintillators were developed Radioactive contamination of (Ca, Zn, Cd & 116Cd)WO4, GSO scintillators was measured CaWO4 and ZnWO4 were studied as detectors to search for 2 decay processes in 48Ca and 64Zn, and as dark matter detectors APP (2005); NIMA (2005) in press; nucl-ex/0409014, accepted to NIMA Study of PbWO4, BGO, GSO, YAG:Nd, CaMoO4 crystal scintillators to search for rare processes is in progress nucl-ex/0412021; nucl-ex/0410021, accepted to NIM A

Current status of research in Solotvina Advancement of the 116Cd  experiment: 3-51024 yr  m  0.3 eV Low counting experiments in collaboration with Roma 1 & 2 Universities and LNGS Modernization of the Solotvina Underground Laboratory will be realized in 2005 thanks to financing from the Ukrainian National Academy of Sciences

The Solotvina Underground Laboratory would like to participate in the ILIAS PROGRAMM