[en] A search for postulated (²⁴⁷CmX^-) has been carried out. This nuclide is expected to have chemical properties similar to americium. A trivalent actinide-lanthanide fraction which would contain any americium was radiochemically isolated from hot brines from the 'Atlantis-II deep region' of the Red Sea. Its alpha and spontaneous fission (SF) activity was measured. No unknown alpha activity was observed. Assuming (²⁴⁷CmX^-) has an alpha energy of 4.35 MeV, a limit of < 10¹² atoms per gram of dried Atlantis-II precipitate can be calculated. Furthermore, no spontaneous fission activity was observed, giving a limit of < 8x10^-8 SFxmin^-1xg^-1. (orig.)

[en] Full text: The search for supernova-produced, long-lived radionuclides on earth, will give an improved insight into explosive nucleosynthesis scenarios. We explored the detection of very small traces of the long-lived radionuclides ²⁴⁴Pu (t_1/2 = 81 Ma) and ²⁴⁷Cm (15.6 Ma) at the Vienna Environmental Research Accelerator (VERA) laboratory. Such a finding would be of great interest in nuclear astrophysics complementing the recent detection of possibly supernova produced ⁶⁰Fe. Nuclear astrophysics aims at describing nuclear processes relevant to nucleosynthesis. At VERA we are pursuing a program to study such cross sections. An overview on recent activities of the AMS technique in nuclear astrophysics will be given, including measurements relevant for Big-Bang and stellar nucleosynthesis and the search for SN-produced radionuclides on Earth. (author)

[en] The neutron cross sections of Cm-247 are evaluated in the resonance (resolved and unresolved) region up to 10 keV. Average resonance parameters (i.e. spacing D, fission and radiative widths, neutron strength functions) are determined for unresolved region calculations. Moreover for a better comparison with the experimental data, fission cross section is calculated up to 10 MeV. In addition, the average number of neutrons emitted per fission as a function of energy is estimated

No abstract available

[en] In order to search for isotopic anomalies of U caused by the disintegration of ²⁴⁷Cm in meteorite samples, an analytical scheme for determining ²³⁵U/²³⁸U ratio for a small amount of uranium (less than 1 ng U) was established. The isotopic ratio of U was determined by double-focusing inductively coupled plasma mass spectrometry (DF-ICP-MS). With a great improvement of chemical procedure for purifying the uranium fraction separated from meteorite samples, a variation in ²³⁵U/²³⁸U ratios was resolved at an order of ±4 per mille for 100 ppt or 200 pg U in solution. For applying the procedure in searching an evidence of ²⁴⁷Cm as an extinct radionuclide in the early solar system, a selective chemical dissolution of constituent minerals of meteorites using EDTA and HCl was introduced and a chemical purification scheme of uranium for ICP-MS was established. (author)

[en] Full text: It is of great interest to detect and trace freshly produced elements as a direct proof of our understanding of nucleosynthesis. The production of lighter elements can be studied in the laboratory, and in-space γ-rays from the decay of e.g. ²⁶Al and ⁴⁴Ti can nowadays be observed via space-born instruments. Many nuclear reactions near the valley of stability have been studied in the laboratory, and radioactive beam facilities now open a wide area for studying reactions off stability. However, one important issue is the experimental proof of r-process scenarios via the direct observation of nuclides generated in the r-process. Some ten years ago it was pointed out that there might be a chance for finding long-lived radionuclides in terrestrial archives, which were originally produced in a supernova (SN). Several candidates had been identified, among them ²⁶Al, ⁵³Mn, ⁶⁰Fe, ¹⁴⁶Sm, ¹⁸²Hf, ²⁴⁴Pu which are produced in sufficient amounts to be in principle detectable on Earth. We explore the detection of very feeble natural traces of the long-lived radionuclides ²⁴⁴Pu (t_1/2 = 81 Ma) and ²⁴⁷Cm (15.6 Ma). Such a finding would be of great interest in nuclear astrophysics complementing the recent detection of possibly supernova-produced ⁶⁰Fe. The expected extremely small concentrations of ²⁴⁴Pu and ²⁴⁷Cm, makes accelerator mass spectrometry (AMS) as the favorite method. First measurements of ²⁴⁴Pu looking for a supernova-produced evidence have been performed recently in deep-sea manganese nodules and deep-sea sediments. These measurements are at the edge of detection limit. At the VERA laboratory we have continued to search for ²⁴⁴Pu and have extended our search to the radionuclide ²⁴⁷Cm. Compared to previous ²⁴⁴Pu measurements, ten times higher sample mass is now available. Due to the long half-lives of ²⁴⁴Pu and ²⁴⁷Cm, one can reach back in time much further than with ⁶⁰Fe. In addition to single events, one may be sensitive to the steady-state abundance of these nuclides in the interstellar medium. Recently, AMS at VERA (Vienna Environmental Research Accelerator) has reached a state of refinement for detection of trans-uranium elements, that we found it worthwhile to embark on a new search for super-heavy elements in nature. Isotopic spot-checks are performed around mass regions predicted to be the most stable ones beyond Z = 100 (e.g. A=298, Z=114, and A=292, Z=120). We will report on first exploratory experiments of this project. (author)

[en] Full text: Accelerator Mass Spectrometry (AMS) - being independent on the half-life of a radionuclide - provides a technique to determine isotope ratios with the highest sensitivity and allows the measurement of radionuclides over a wide dynamic range of concentration levels. A combination of AMS, Alpha Spectrometry and Liquid Scintillation Counting was used for the determination of the complete information on isotope ratios of Plutonium isotopes in different environmental reference samples (e.g. from the atolls of Mururoa and Fangataufa) and samples contaminated from nuclear reprocessing. Results for the isotopic ratios of the samples will be shown and the capabilities and detection limits achievable for determination of Pu will be discussed. The long-lived ²⁴⁴Pu (t_1/2 = 80 Ma) and ²⁴⁷Cm (t_1/2 = 15.6 Ma) have a very interesting application in astrophysics by detecting possible supernova-produced ²⁴⁴Pu and ²⁴⁷Cm in terrestrial archives. The expected extremely small concentrations of ²⁴⁴Pu makes AMS the favorite method. The actual search for such long-lived extraterrestrial radionuclides and possible implications will be presented. The same method has also been explored for a pinprick-search of long-lived super-heavy elements in the mass region above Z=100. (author)

[en] A series of fission cross section measurements were performed on ²⁴⁷Cm, ²⁵⁰Cf and ²⁵⁴Es. This paper summarizes the most recent results and details the resonance parameter analysis done on ²⁴⁷Cm

No abstract available

No abstract available