Papers by Thomas Faestermann
Physical Review Letters, 1974
The Pauli exclusion principle has been tested for atomic electrons giving a lifetime for such a v... more The Pauli exclusion principle has been tested for atomic electrons giving a lifetime for such a violation, per iodine atom, of & 2 &102~s ec. This result is compared to a normal electromagnetic dipole transition, and a limit is set on a possible symmetric wave-function admixture to a X-shen electron wave function.
AIP Conference Proceedings, 2018
The successful searches for radioactive material expelled by one or several close supernovae and ... more The successful searches for radioactive material expelled by one or several close supernovae and deposited on Earth and Moon are reviewed. A surplus of 60 Fe has been found at eight locations in terrestrial oceans as well as in Lunar samples. This surplus is attributed to supernova activity within 300 light years from the sun about 1.5 to 3.0 Ma ago. The mechanism of core-collapse SNe is described as well as the extremely sensitive detection method of accelerator mass spectrometry (AMS).
AIP Conference Proceedings, 2000
... 32 Page 10. REFERENCES 1. Jackson, KP, Cardinal, CU, Evans, HC, Jelley, NA, Cerny, J., Phys. ... more ... 32 Page 10. REFERENCES 1. Jackson, KP, Cardinal, CU, Evans, HC, Jelley, NA, Cerny, J., Phys. Lett. ... Munich, 129-130 (1986) 18. Heine, F., Faestermann, T., Gillitzer, A., Homolka, J., Kopf, M., Wagner, W., Z Phys. A340, 225-226 (1991) 19. ...
Physica Scripta, 2015
In this review lifetime measurements of ions with at most two electrons are summarized. Such high... more In this review lifetime measurements of ions with at most two electrons are summarized. Such highly ionized systems have been studied-until now-only in the Experimental Storage Ring of the GSI in Darmstadt. Emphasis is put on decays via the weak interaction. The first observations of beta-decay into bound atomic states are described as well as its time mirrored counterpart, the electron-capture decay. In the latter case the decays of hydrogen-and helium-like ions are compared with a surprising result. Further on, the observation of sinusoidal modulations of the decay rate in two-body decays is summarized. As a possible cause an interference due to the emission of neutrinos with different rest mass is discussed.
Zeitschrift f�r Physik A Atomic Nuclei, 1987
The g-factor ratio of the first excited 3-and 5-states in 4~ was measured to be g3/g5 = 1.01(10) ... more The g-factor ratio of the first excited 3-and 5-states in 4~ was measured to be g3/g5 = 1.01(10) employing the implantation perturbed angular correlation technique. The static hyperfine fields (SF) in Fe and Gd hosts were used. In addition the lifetime of the 5-state was measured to be z=426(7)ps. The values of the SF in Gd and Fe hosts were deduced and compared with systematics in this element region.
ABSTRACT Relatively high concentrations of live ^6^0Fe (T_1/2 = 2.62 ± 0.04 Ma) in lunar surface ... more ABSTRACT Relatively high concentrations of live ^6^0Fe (T_1/2 = 2.62 ± 0.04 Ma) in lunar surface samples confirm earlier work and suggest the arrival of supernova (SN) debris on the Moon about 2 Ma ago.
Platinum isotopes have been measured in presolar nanodiamond residues from the Allende and Murchi... more Platinum isotopes have been measured in presolar nanodiamond residues from the Allende and Murchison meteorites using accelerator mass spectrometry (AMS). We infer an upper limit to the abundance of 198 Pt-H of ~1x10 14 atoms/g, which is on the order of what is expected from an extrapolation of the apparently mass dependent abundance trend of the associated noble gases. Introduction: Presolar nanodiamonds are the most enigmatic type of presolar grain found in primitive meteorites (e.g., [1,2]). The inference about a presolar origin of at least part of them only rests on the isotopic analysis of trace elements such as noble gases (e.g., [3,4]). However, typically just one out of a million diamond grains contains an atom of these, and it is not possible to quantify the fraction of diamonds that are truly presolar. The major hints come from elements that are located in the Solar System abundance distribution on the first two r-process abundance peaks associated with magic neutron numbers N=50 (Kr) and N=82 (Te, Xe) [3-6]. It seemed worthwhile, therefore, to search for correlated effects in elements of the third peak (N=126) such as platinum. Experimental: AMS was chosen to determine the isotopic composition of platinum in two diamond residues, in order to avoid the potential problem of molecular and isobaric interferences. While this is also well achieved by RIMS, which also can have considerably higher detection efficiency (e.g. [7]), AMS is more easily adapted to measurement of a new element, and it seemed worthwhile to explore its applicability. Moreover, since unlike the case of SiC and graphite, diamonds cannot be analyzed individually anyway, detection efficiency is of lesser importance in their study. The experimental setup was similar to that used for the measurement of actinides [8]. Diamonds were mixed with high purity Ag powder and pressed in Ag cathodes, which were introduced into a sputter ion source. Negative Pt ions were extracted and, after a first magnetic mass selection, injected into the tandem accelerator, running at a terminal voltage of 9.5 MV. The stripping process in the accelerator's terminal provides an entire molecular breakup, thus any molecular background can be rejected on the highenergy side of the AMS system. After the accelerator, Pt ions in the 8 + charge state were selected. To switch between the different Pt isotopes, the terminal voltage was adjusted for an equal magnetic rigidity of the ions
Physical Review C, Jul 10, 2023
More than 200 states up to 4.1 MeV excitation have been populated in 168 Er with the 170 Er(p, t)... more More than 200 states up to 4.1 MeV excitation have been populated in 168 Er with the 170 Er(p, t) reaction at 25 MeV incident energy. About 80 of these states, with 0 + and 2 + assignments, were reported in a previous publication [D. Bucurescu et al., Phys. Rev. C 73, 064309 (2006)]. The present work considerably enriches the knowledge of this nucleus. A multistep coupled-channels analysis of the angular distributions is now presented for all the states observed in this experiment. Spin and parity values between 0 + and 7 − are newly assigned for more than 100 states. For the states already reported in the ENSDF database with J π values there is a good agreement with our values. The 168 Er nucleus remains one of the best experimentally known nuclei for states with low and medium spins below 4 MeV excitation energy, representing a challenge for future microscopic structure model calculations aiming to disentangle the contributions of different excitation degrees of freedom.
Acta Physica Polonica B, 2012
Meteoritics & Planetary Science, 2020
We measured specific activities of the long‐lived cosmogenic radionuclides 60Fe in 28 iron meteor... more We measured specific activities of the long‐lived cosmogenic radionuclides 60Fe in 28 iron meteorites and 53Mn in 41 iron meteorites. Accelerator mass spectrometry was applied at the 14 MV Heavy Ion Accelerator Facility at ANU Canberra for all samples except for two which were measured at the Maier‐Leibnitz Laboratory, Munich. For the large iron meteorite Twannberg (IIG), we measured six samples for 53Mn. This work doubles the number of existing individual 60Fe data and quadruples the number of iron meteorites studied for 60Fe. We also significantly extended the entire 53Mn database for iron meteorites. The 53Mn data for the iron meteorite Twannberg vary by more than a factor of 30, indicating a significant shielding dependency. In addition, we performed new model calculations for the production of 60Fe and 53Mn in iron meteorites. While the new model is based on the same particle spectra as the earlier model, we no longer use experimental cross sections but instead use cross sectio...
Proceedings of XII International Symposium on Nuclei in the Cosmos — PoS(NIC XII), 2013
A new method is proposed to determine half-lives and branching ratios of β-delayed neutron emitte... more A new method is proposed to determine half-lives and branching ratios of β-delayed neutron emitters, especially those beyond N=126 that are relevant for the r-process. The existing storage ring ESR or the future ring CR at GSI would be employed to store and cool the mother nuclei. The decay half-life and the neutron emission probability could be deduced from the detection of the mother and decay daughter ions with Schottky pickups and a particle detector in contrast to the standard method via detection of β-delayed neutrons. This method could be complementary and has the advantage to be independent of the neutron detection efficiency. As candidates for a proof-of-principle tests we suggest the nuclei 211 Hg, 212 Hg, 210 Tl, and 213 Tl which have been investigated in a recent experiment by traditional detection methods.
Proceedings of 11th Symposium on Nuclei in the Cosmos — PoS(NIC XI), 2011
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2019
The AMS setup at the Maier-Leibnitz-Laboratory (MLL) in Garching features a 14 MV tandem accelera... more The AMS setup at the Maier-Leibnitz-Laboratory (MLL) in Garching features a 14 MV tandem accelerator and two dedicated beam lines for high-sensitivity measurements of isotopes in all mass ranges. Especially in the medium mass range (70 < A < 120), AMS sensitivity is often limited by isobaric and isotopic background with only small relative difference in Z and/or A. Here, we present recent developments and upgrades at the MLL with special focus on improved sensitivity and new techniques for challenging AMS isotopes such as 93 Zr and 99 Tc. Upgrades of the measurement setup as well as radiopurity studies for AMS samples, which could be altered by atmospheric neutrons during transportation by aircraft, are discussed.
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Papers by Thomas Faestermann