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キーワード:
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要旨:
Real-time solar neutrino detectors require large quantities of extremely pure target and shielding materials. Water is widely used as it is readily available and can be easily purified. Especially the noble gas radon as well a radium, its long-lived progenitor, have to be carefully removed to achieve a low background rate. The off-line radon/radium assay of water plays an important role in all the present real-time solar neutrino experiments. The techniques applied by the different groups are described and compared here. Sensitivities below 100 muBq/m(3) for radon and radium have been achieved.