[en] Recent ₄₀Ar-₃₉Ar dating of especially selected North Ray crater ejecta breccias revealed time marks at 4.1 AE, 3.85 AE, 3.55 AE, 3.24 AE, and 0.38 AE. Their selenological significance will be the topic of further consortium studies. (orig.)

[en] The installation of an ESCA (Electron Spectroscopy for Chemical Analysis) apparatus for studies complimentary to our SIMS analyses was continued. The energy-calibration of the ESCA-spectrometer disclosed problems in the stability of the analyzer sweep voltage which were solved by connecting the digital-analog-converter to the same ground potential as the ESCA-electronics. Afterwards calibration was performed using a copper and a gold target. The analysis of two more complex samples confirmed the accuracy of the calibration. The precision of the energy-scale is better than ±0.2 eV. (orig.)

[en] This annual report contains short descriptions of the research performed at the given institute together with an extensive list of publications. The research in nuclear physics is concerned with developments in accelerators and ion sources, radiation detectors, solid-state studies by nuclear methods, counting circuits, data processing, target preparation, fission, fusion, and nuclear friction, giant resonances, nuclear spectroscopy, nuclear reaction mechanisms, atomic physics and interaction of charged particles with matter, medium and high energy physics. The research in cosmophysics works on meteorites and lunar rocks, the gallium-solar-neutrino experiment (project GALLEX), problems of Halley's comet, interplanetary and interstellar dust, planetary atmospheres, interstellar medium and cosmic rays, molecular collision processes in the gas phase, nuclear geology and geochemistry, and archaeometry. (GG)

No abstract available

[en] The present discussion of recent studies concerning cometary composition gives attention to the results obtained by in situ measurements of Comet Halley's dust composition by Vega 1's impact mass spectrometer, which discovered a mineral fraction that appears to be CI chondritic, as well as an organic fraction consisting of highly unsaturated hydrocarbons. The mineral fraction of comets appears to form a core that is embedded in essentially organic material; the spectroscopic invisibility of carbon is due to its presence in the cometary dust. The mass of most dust particles is found to be in the 10 to the -12th to 10 to the -14th g range. A considerable fraction of the dust grains serves as an extended source of gas in the inner coma

[en] The violation of leptonic charge conservation in Neutrinoless Double Beta Decay is made possible either by a right handed current admixture (amplitude eta) to the leptonic current or by a non-vanishing neutrino restmass. Particularly stringent limits on msub(ß) and eta result from the ratio of Double Beta Decay rates of ₁₂₈Te and ₁₃₀Te. From our determination of this ratio applying the geochemical method to a Precambrian Tellurium ore we obtain a limit of msub(ß) <= 5.6 eV (2sigma). (orig.)

[en] This is a report on the isotopic composition of argon found in neutron-irradiated quartz ampoules which contain samples of Allende coarse-grained inclusions or aluminium wrap only, and of argon released from one of these inclusions by stepwise heating. Besides atmospheric argon all ampoules contain, with varying concentrations but in constant proportions, ³⁸Ar from Cl and ³⁹Ar from K corresponding to Cl/K approx.= 1. No ³⁹Ar which has recoiled out of the samples and no argon which has diffused out of the samples has been observed in the ampoule gas. The analysis of the isotope variations of argon released by stepwise heating from a sample of inclusion 18 yields an apparent ⁴⁰Ar-³⁹Ar isochron age of 4.85 AE. A re-analysis of argon from another sample of the same inclusion dated earlier yields the same result. Thus inclusion 18 contains more radiogenic ⁴⁰Ar than can be accounted for by ⁴⁰K decay during 4.53 AE. (orig.)

[en] Lanphere and Dalrymple in a recent paper demonstrate that in dating one sample the ⁴⁰Ar-³⁹Ar technique is capable of detecting the presence of extraneous ⁴⁰Ar which is not possible with the conventional K-Ar method. This comment shows that their data if properly interpreted serve to set limits for the applicability of the ⁴⁰Ar-³⁹Ar technique in the presence of extraneous ⁴⁰Ar. (Auth.)

[en] As part of the consortium effort to study the Jilin (H5) meteorite two documented samples from the main mass and one from a smaller strewn field fragment have been dated with the ⁴⁰Ar-³⁹Ar technique. In addition, ⁴He and argon release patterns from a non-irradiated sample were determined to obtain diffusion parameters. Concordant ⁴⁰Ar-³⁹Ar ages of proportional4.0 AE indicate that Jilin was totally degassed at that time. Using also the results from other consortium studies, it is shown that largely varying secondary ⁴⁰AR and ⁴He losses are related to the position of the samples within the pre-atmospheric meteoroid. This sets rather stringent limits to the temperature history of Jilin: The surface of the meteoroid was heated probably 400.000 years ago at the separation from its parent body. Model calculations suggest that the heating event was moderate (initial surface temperature 500-600⁰C) and brief (surface cooling rate 1-2⁰C/h). Heating of meteoroids at separation from their parent bodies might be a common phenomenon. It could explain ''late'' disturbances in some isotope systems and could be the driving force for hydrothermal alterations. The age of the reheating does not at all become apparent in the ⁴⁰Ar-³⁹Ar data calling in question the use of low-temperature ⁴⁰Ar-³⁹Ar ages to date multi-collisional events in meteorite parent bodies. (orig.)

[en] Ar-40/Ar-39 studies of seven low petrographic type L and H chondrites from Antarctica are presented. The hypothesis of McKinley et al. (1981) that the L3 chondrites ALHA77015, -77167, -77249, and -77260 are from a common fall is confirmed. It is shown that the Ar-degassing patterns of the four meteorites are identical. Also, the chondrites have similar K, Ca, Cl, and trapped Ar-39 contents and Ar-40/Ar-39 ages. 19 references