Speaker
Dr
Fedor Danevich
(Institute for Nuclear Research, Kyiv, Ukraine)
Description
Cadmium tungstate crystal scintillators enriched in 106Cd up to 66% (106CdWO4) and 116Cd up to 82% (116CdWO4) have been developed to investigate double beta processes in 106Cd and 116Cd. The metal samples of the enriched cadmium were purified by heating with filtration in combination with distillation through getter filters. The cadmium tungstate compounds were synthesized from solutions by using quartz or polypropylene lab-ware, materials with low level of radioactive contaminations, and reagents of high purity grade (concentration of any metal less than 0.01 ppm). The 106CdWO4 and 116CdWO4 crystal boules with masses of 231 g and 1868 g, respectively (87% of initial charges) were grown by the low-thermal-gradient Czochralski technique. The total irrecoverable losses of the isotopically enriched materials in the whole production processes do not exceed 2%. The produced scintillators exhibit excellent optical and scintillation properties thanks to the deep purification of the initial materials and utilization of the low-thermal-gradient Czochralski method to grow the crystals. Radioactive contamination of the scintillators was measured both by scintillation method and using ultra-low-background HPGe gamma detectors. The contamination of the crystals is on the level of <1.5 mBq/kg (40K), <0.005-0.012 mBq/kg (226Ra), 0.04-0.07 mBq/kg (228Th), 2-3 mBq/kg (total alpha activity). We have observed a considerable activity of 113mCd in both the crystals: 116 Bq/kg in the 106CdWO4 and 0.46 Bq/kg in the 116CdWO4. The measurements of the scraps of the melt after the 116CdWO4 crystal growth by using an ultra-low-background HPGe detector indicate a very low segregation of thorium, radium and potassium, which gives a strong motivation to re-crystallize the crystals with an aim to improve further their radiopurity in 228Th and 226Ra. Experiments to search for double beta processes in 106Cd and 116Cd by using the crystal scintillators are in progress at the underground Gran Sasso National Laboratories of the INFN (Italy).
Primary author
Dr
Fedor Danevich
(Institute for Nuclear Research, Kyiv, Ukraine)
Co-authors
Prof.
Alexander Barabash
(Institute of Theoretical and Experimental Physics, Moscow, Russia)
Mr
Alexander Mikhlin
(Joint Stock Company NeoChem, Moscow, Russia)
Mr
Alexei Dossovitskiy
(Joint Stock Company NeoChem, Moscow, Russia)
Dr
Alexei Shcherban
(National Science Center Kharkiv Institute of Physics and Technology, Kharkiv, Ukraine)
Dr
Andrew Nikolaiko
(Institute for Nuclear Research, Kyiv, Ukraine)
Dr
Antonella Incicchitti
(INFN, Section of Rome “La Sapienza”, Rome, Italy; Department of Physics, University of Rome “La Sapienza”, Rome, Italy)
Dr
Denys Poda
(Institute for Nuclear Research, Kyiv, Ukraine)
Ms
Dmitry Chernyak
(Institute for Nuclear Research, Kyiv, Ukraine)
Mr
Dmitry Solopikhin
(National Science Center Kharkiv Institute of Physics and Technology, Kharkiv, Ukraine)
Mr
Evgeny Galashov
(Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)
Dr
Fabio Capella
(INFN, Section of Rome “La Sapienza”, Rome, Italy; Department of Physics, University of Rome “La Sapienza”, Rome, Italy)
Prof.
Gennady Kovtun
(National Science Center Kharkiv Institute of Physics and Technology, Kharkiv, Ukraine)
Mrs
Marialaura Di Vacri
(INFN, Gran Sasso National Laboratories, Assergi (Aq), Italy)
Dr
Matthias Laubenstein
(INFN, Gran Sasso National Laboratories, Assergi (Aq), Italy)
Dr
Oksana Polischuk
(INFN, Section of Rome “La Sapienza”, Rome, Italy; Institute for Nuclear Research, Kyiv, Ukraine)
Dr
Pierluigi Belli
(INFN, Section of Rome “Tor Vergata”, Rome, Italy)
Dr
Riccardo Cerulli
(INFN, Gran Sasso National Laboratories, Assergi (Aq), Italy)
Prof.
Rita Bernabei
(INFN, Section of Rome “Tor Vergata”, Rome, Italy; Department of Physics, University of Rome “Tor Vergata”, Rome, Italy)
Dr
Roman Boiko
(Institute for Nuclear Research, Kyiv, Ukraine)
Dr
Ruslan Podviyanuk
(Institute for Nuclear Research, Kyiv, Ukraine)
Dr
Sergei Konovalov
(Institute of Theoretical and Experimental Physics, Moscow, Russia)
Prof.
Silvio d'Angelo
(INFN, Section of Rome “Tor Vergata”, Rome, Italy)
Mr
Stefano Nisi
(INFN, Gran Sasso National Laboratories, Assergi (Aq), Italy)
Mrs
Valentyna Mokina
(Institute for Nuclear Research, Kyiv, Ukraine)
Prof.
Victor Brudanin
(Joint Institute for Nuclear Research, Dubna, Russia)
Dr
Vincenzo Caracciolo
(INFN, Gran Sasso National Laboratories, Assergi (Aq), Italy; Department of Physics, University of L'Aquila, L'Aquila, Italy)
Prof.
Vladimir Degoda
(Kyiv National Taras Shevchenko University, Kyiv, Ukraine)
Dr
Vladimir Shlegel
(Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)
Dr
Vladimir Tretyak
(Institute for Nuclear Research, Kyiv, Ukraine)
Dr
Vladimir Umatov
(Institute of Theoretical and Experimental Physics, Moscow, Russia)
Mr
Vladimir Virich
(National Science Center Kharkiv Institute of Physics and Technology, Kharkiv, Ukraine)
Dr
Vladislav Kobychev
(Institute for Nuclear Research, Kyiv, Ukraine)
Dr
Yan Vasiliev
(Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)
