To precisely measure radon concentrations in purified air supplied to the Super-Kamiokande detector as a buffer gas, we have developed a highly sensitive radon detector with an intrinsic background as low as 0.33 ± 0.07 mBq/m 3 . In this article, we discuss the construction and calibration of this detector as well as results of its application to the measurement and monitoring of the buffer gas layer above Super-Kamiokande. In March 2013, the chilled activated charcoal system used to remove radon in the input buffer gas was upgraded. After this improvement, a dramatic reduction in the radon concentration of the supply gas down to 0.08 ± 0.07 mBq/m 3 . Additionally, the Rn concentration of the in-situ buffer gas has been measured 28.8±1.7 mBq/m 3 using the new radon detector. Based on these measurements we have determined that the dominant source of Rn in the buffer gas arises from contamination from the Super-Kamiokande tank itself.

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T-588 has a neuroprotective effect against RGC death caused by elevated IOP and optic nerve crush in the rat.

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[1] Measurements of atmospheric 222 Rn activity were made on board the icebreaker Shirase during the summers of 2004 and 2005, between 32 ı S and 69 ı S. Global atmospheric 3-D model calculation of 222 Rn were conducted using hypothetical emissions from ocean and land including the Antarctic continent. Oceanic emissions were estimated based on wind speed parameterizations from the literature and by using radium in the ocean as a surrogate of surface radon concentrations. Modeled results suggest that a significant part of the measured activities originate from a release from the ocean and the Antarctic continent. Based on regression analysis, we investigated the power-law description of wind speed that best fits the measured concentrations. The correlation, root mean square errors, and emission from the Antarctic continent suggest that a 3.5 power law best fits the measured activities. However, the merit of this choice is not statistically significant, and the proportionality factor that scales a wind speed description with a flux depends on the dilution of radon in the mixing layer of the ocean. These weaknesses, therefore, pose a limitation for the application of the current parameterization to the other gases.Citation: Taguchi, S., S. Tasaka, M. Matsubara, K. Osada, T. Yokoi, and T. Yamanouchi (2013), Air-sea gas transfer rate for the Southern Ocean inferred from 222 Rn concentrations in maritime air and a global atmospheric transport model,