5 research outputs found
High purity NaI(Tl) scintillator to search for dark matter
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 Ra was reduced less than 100 Bq/kg in
NaI(Tl) crystal. It should be remarked that the impurity of Pb, which
is difficult to reduce, is effectively reduced by chemical processing of NaI
raw powder down to less than 30 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 710 cm for 50 GeV WIMPs.Comment: 6 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
Exposure to Radiofrequency Electromagnetic Field in the High-Frequency Band and Cognitive Function in Children and Adolescents: A Literature Review
With increasing use of mobile phones, exposure to radiofrequency electromagnetic field (RF-EMF) in the high-frequency band associated with mobile phones has become a public concern, with potentially adverse effects on cognitive function in children and adolescents. However, findings regarding the relation of RF-EMF and cognitive function in children and adolescents have been inconsistent due to a number of study design-related factors, such as types of exposure and outcome measures, age of participants, and the era of study conduction. The present literature review focused on these possible factors that could explain this inconsistency. This review identified 12 eligible studies (participants ages 4 to 17 years) and extracted a total 477 relations. In total, 86% of the extracted relations were not statistically significant; in the remaining 14%, a negative relation between RF-EMF and cognitive performance was detected under limited conditions: when (1) RF-EMF was assessed using objective measurement not subjective measurement (i.e., questionnaire), (2) participants were relatively older (12 years and above) and had greater opportunity of exposure to RF-EMF, and (3) the collection of cognitive function data was conducted after 2012. Given that 86% of the extracted relations in this analysis were not statistically significant, the interpretation should be approached with caution due to the possibility of the 14% of significant relationships, extracted in this review, representing chance findings