Reduction of the Radioactivity in Molybdenum Trioxide Powder and Study of Calcium Molybdate Compound for the AMoRE Experiment

by Sujita Karki (Ph.D Candidate)

Monday May 27, 2019, 4:00 PM → 5:00 PM Asia/Seoul

119호 (제1과학관)

Advanced Molybdenum–based Rare process Experiment (AMoRE) is a large-scale experiment to search for neutrinoless double beta decay (0νββ) of 100Mo in Molybdenum–based scintillating crystals using low temperature calorimeters. The crystals which are being used as a detector material should be free from the intrinsic radioactive impurities such are U, Th and Ra in order to avoid the internal background for the expected 0νββ peak. Furthermore, there are no commercially available MoO3 and enriched 100MoO3 powders which have required levels of radioactive contaminations. This research intends to develop preliminary techniques for purification of radioactive contaminants from commercial MoO3 powders. Hence, the optimized techniques will be used for purifying the enriched 100MoO3 powder which is to be used for making the 100Mo contained crystal detector.
Various chemical and physical separation methods such as: solvent extraction, recrystallization, sublimation, precipitation and co-precipitation methods are studied to remove these impurities in the levels of few ppt and few tens of μBq/kg. The concentrations of the metal impurities were analyzed by using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and the contents of radioactivities were measured by using High Purity Germanium detector (HPGe). The isotopic ratios of 100Mo- and 48Ca- in the 40Ca100MoO4 crystal have been studied for the AMoRE phase-I experiment. For growing single crystals of CaMoO4, the CaMoO4 powders are synthesized by wet chemistry method and the properties of the synthesized powders are reported.

Thesis Advisor: Prof. Hongjoo Kim