Chlorine-39 in rainfall at a temperate latitude (40 degrees N).
Rainwater samples were collected and measured for the radioactivity to confirm the presence of Chlorine-39 (T1/2=56.2 min) formed by the interaction of cosmic-ray slow negative muons, mu- with Argon-40 in the lower atmosphere. The presence of 39Cl was confirmed by estimating the half-life of a radionuclide present in the rainwater ranging from 58 to 63 min and averaging 60.4 min. The disintegration rate of this radionuclide varied from 2.1 to 2.7 Bq L(-1) (125-160 dpm/L) of rainwater and averaged 2.3 Bq L(-1) (140 dpm/L) of rainwater in Thessaloniki (40 degrees 38'N, 22 degrees 58'E), Northern Greece. This concentration is indicative of mid or temperate latitudes. This is clearly less than that reported in the literature, 1.7 Bq L(-1) (100 dpm/L) of rainwater, for a southern latitude 31 degrees 54'N, 34 degrees 49'E (Rehovot, Israel), due to the latitudinal effect of cosmic radiation.
Papastefanou
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Aristotle University of Thessaloniki, Atomic and Nuclear Physics Laboratory, Thessaloniki 54124, Greece. papastefanou@physics.auth.gr
D000396:Air Pollutants, Radioactive / Q000032:analysis*; D001128:Argon / Q000528:radiation effects; D002713:Chlorine / Q000032:analysis*; D002980:Climate; D003359:Cosmic Radiation; D004784:Environmental Monitoring; D008651:Mesons; D011868:Radioisotopes / Q000032:analysis*; D011891:Rain / Q000737:chemistry*
D000396:Air Pollutants, Radioactive; D011868:Radioisotopes; D002713:Chlorine; D001128:Argon