caa a22 4500 465732119 CHVBK 20180323111744.0 cr unu---uuuuu 170327e19900701xx s 000 0 eng 10.1007/BF02060183 doi (NATIONALLICENCE)springer-10.1007/BF02060183 Sheng Z. Department of Physics, University of Arkansas, 72701, Fayetteville, AR, (USA) aut Isotopic compositions of terrestrial thorium: A search in terrestrial thorium for the unidentified excess 4.6 meV alpha-activity of lunar thorium [Elektronische Daten] [Z. Sheng] Since thorium in lunar crystalline rocks was reported to be excessive in 4.6 MeV alpha-activity up to 80%, which was attributed to a long-lived isomer of232Th with an origin different from normal thorium, we have measured alpha-spectra of various terrestrial thorium in order to see if terrestrial thorium also contains some excess 4.6 MeV alpha-activity. The results showed that the content of the excess 4.6 MeV alpha-activity in terrestrial thorium, if any, is much less than 3%. An approach to set an upper limit for the excess alpha-activity in terrestrial thorium is proposed. The origin of the excess alpha-activity is discussed. Akadémiai Kiadó, 1990 Journal of Radioanalytical and Nuclear Chemistry Kluwer Academic Publishers 141/1(1990-07-01), 41-47 0236-5731 141:1<41 1990 141 10967 https://doi.org/10.1007/BF02060183 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02060183 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Sheng Z. Department of Physics, University of Arkansas, 72701, Fayetteville, AR, (USA) aut NATIONALLICENCE 773 0- Journal of Radioanalytical and Nuclear Chemistry Kluwer Academic Publishers 141/1(1990-07-01), 41-47 0236-5731 141:1<41 1990 141 10967 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer