Extra-terrestrial 53Mn in Antarctic ice |
| |
| Authors: | R Bibron R Chesselet G Crozaz G Leger JP Mennessier E Picciotto |
| |
| Institution: | 1. Service d''Electronique Physique, Centre d''Etudes Nucléaires de Saclay (C.E.N.-S.), Commissariatàl''Energie Atomique (C.E.A.),France.;2. Centre des Faibles Radioactivités, Laboratoire Mixte; Centre National de la Recherche Scientifique (C.N.R.S.), Commissariatàl''Energie Atomique (C.E.A.), Gif-sur-Yvette ,France.;3. Chargée de Recherche au Fonds National de la Recherche Scientifique (F.N.R.S.),Belgique.;4. Service de Géologie et Géochimie Nucléaires, UniversitéLibre de Bruxelles (U.L.B.),Belgique. |
| |
| Abstract: | The reasons why53Mn (a cosmogenic radionuclide with a half-life of 3.7 × 106 y) appears as one of the best indicators of the presence of interplanetary dust are summarized. This paper reports the detection of53Mn in pre-1952 snow samples collected on the Eastern Antarctic Plateau in the vicinity of Plateau Station. The measurements were carried out by neutron activation and X-ray spectrometry on three samples weighing a few hundred kg and covering each the time interval 1935–1950. The specific activity of53Mn was found to be (0.82 ± 0.17) disint.min?1/103 tons of snow, corresponding to a deposition rate at Plateau Station of (2.2 ± 0.5) × 10?5 disint. min?1 m?2 y?1. The mean global deposition rate would be three times higher if53Mn were assumed to behave in the same way as stratospheric90Sr. By comparing this figure with existing data on the meteorite flux reaching the earth and with the galactic and solar production rates of53Mn, it is concluded that the bulk of the53Mn found at Plateau Station is associated with interplanetary dust in which it had been produced by the action of solar protons on iron. The deposition rate of extra-terrestrial dust-borne iron must be between 1.3 × 10?5 and 1.3 × 10?4 g m?2 y?1 at Plateau Station. These results support jointly with other studies the concept of an interplanetary zodiacal cloud of dust with a chemical composition and density not essentially different from chondritic meteorites, with a relatively ‘flat’ grain size distribution and a mass influx to the earth of the order of 105 tons/y. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
