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Cosmogenic radionuclides measured by accelerator mass spectrometry, and other cosmic ray products were analyzed in multiple samples of 2 large L chondrites (Mocs and Ghubara) and individual samples of 47 H chondrites. Physical relationships of samples in parent meteoroids, exposure histories and statistical relationships of nuclides were construed.
A wide variety of products from cosmic-ray interactions have been measured in terrestrial or extraterrestrial samples. These ''cosmogenic'' products include radiation damage tracks and rare nuclides that are made by nuclear reactions. They often have been used to determine the fluxes and composition of cosmic-ray particles in the past, but they are usually used to study the history of the ''target'' (such as the time period that it was exposed to cosmic-ray particles). Products made by both the high-energy galactic cosmic rays and energetic particles emitted irregularly from the Sun have been extensively studied. Some of these cosmogenic products, especially nuclides, have been or can be applied to studies of Antarctic meteorite stranding surfaces, the ice surfaces in Antarctica where meteorites have been found. Cosmogenic nuclides studied in samples from Antarctica and reported by others elsewhere in this volume include those in meteorites, especially radionuclides used to determine terrestrial ages, and those made in situ in terrestrial rocks. Cosmogenic nuclides made in the Earth's atmosphere or brought in with cosmic dust have also been studied in polar ice, and it should also be possible to measure nuclides made in situ in ice. As an introduction to cosmogenic nuclides and their applications, cosmic rays and their interactions will be presented below and production systematics of cosmogenic nuclides in these various media will be discussed later. 20 refs., 2 tabs.
Monte Carlo calculations of 26Al and 53Mn production due to spallation induced by cosmogenic protons in model meteorite composition similar to L Chondrite has yielded predictions which are consistent with the observed decay rates in L Chondrite stony meteorites. The calculated 26Al production rate (54 dpm/kg) in a 1 m diameter meteorite is within 1/2 S.D. of the mean (49 +- 11 dpm/kg) taken from 100 bulk determinations in L Chondrite samples compiled in Nishiizumi (1987). Similarly calculated average value for 53Mn (223 dpm/kg) is consistent with one S.D. off the mean in the widely scattered 53Mn data (362 +- 113 dpm/kg) compiled by Nishiizumi (1987). 9 refs.
The Symposium 'Meteorite Research' was conceived originally at the second meeting of the UNESCO Working Group on Meteorites, held in Paris October 18-20, 1965, under the chairmanship of Professor J. Orce!' In addition to the Chairman the fol lowing were present: Dr. G. Harbottle, Dr. M. H. Hey, Dr. B. H. Mason, Dr. P. M. Millman, Professor K. I. Sztr6kay. Dr. E. M. Fournier d'Albe represented the UNESCO Secretariat. Recommendation No.4 from the minutes of this meeting reads as follows: "The Working Group, in view ofthe need to strengthen international co-operation in meteorite research, asks that the International Atomic Energy Agency be requested to consider the possibility of organizing, in 1968, an interdisciplinary conference on meteorites, in collaboration with UNESCO and the appropriate international scientific organizations." After approval in principle of this recommendation had been secured from various international agencies and unions, plans for the symposium were consolidated at the third and final meeting of the Working Group, held in Paris October 12-14, 1966, the members in attendance being the same as for the second meeting.