High purity NaI(Tl) scintillator to search for dark matter

Abstract

A high purity and large volume NaI(Tl) scintillator was developed to search for cosmic dark matter. The required densities of radioactive impurities (RIs) such as U-chain, Th-chain are less than a few ppt to establish high sensitivity to dark matter. The impurity of RIs were effectively reduced by selecting raw materials of crucible and by performing chemical reduction of lead ion in NaI raw powder. The impurity of ${}^{226}$Ra was reduced less than 100 $\mu$Bq/kg in NaI(Tl) crystal. It should be remarked that the impurity of ${}^{210}$Pb, which is difficult to reduce, is effectively reduced by chemical processing of NaI raw powder down to less than 30 $\mu$Bq/kg. The expected sensitivity to cosmic dark matter by using 250 kg of the high purity and large volume NaI(Tl) scintillator (PICO-LON; Pure Inorganic Crystal Observatory for LOw-background Neutr(al)ino) is 7$\times$10${}^{-45}$ cm${}^2$ for 50 GeV$/c^2$ WIMPs.

arXiv comment6 pages, 2 Figures, Proceedings of International Symposium on Radiation Detectors and Their Uses (ISRD2016). Talk given on 19th Jan. 2016 by K.Fushimi. To be published in Proceedings will be published as JPS conference proceedings (2016)

References in corpus (13)

• Planck 2013 results. XVI. Cosmological parameters
• Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results
• Dark Matter Results from 225 Live Days of XENON100 Data
• The RAVE Survey: Constraining the Local Galactic Escape Speed
• Final model independent result of DAMA/LIBRA-phase1
• Improved Limits on Scattering of Weakly Interacting Massive Particles from Reanalysis of 2013 LUX data
• Dark matter maps reveal cosmic scaffolding
• The DAMA/LIBRA apparatus
• A search for low-mass WIMPs with EDELWEISS-II heat-and-ionization detectors
• Tests on NaI(Tl) crystals for WIMP search at the Yangyang Underground Laboratory
• Light WIMP search in XMASS
• First data from DM-Ice17
• Direct dark matter search by annual modulation in XMASS-I

Cited by in corpus (4)

• A facility for mass production of ultra-pure NaI powder for the COSINE-200 experiment
• A large area detector for thermal neutron flux measurements at the KamLAND site
• The KDK (potassium decay) experiment
• Reflections on the search for particle dark matter by direct experiments