S. Merchel
Max Planck Society
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Featured researches published by S. Merchel.
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 2004
S. Merchel; Wolfram Bremser
A first international 26Al interlaboratory comparison was initiated and evaluation of the results of the eight participating accelerator mass spectrometry (AMS) laboratories on four synthetic samples shows no difference in the sense of simple statistical significance. However, certain interlaboratory bias is observed with more detailed statistical analyses. Some laboratories seem to underestimate the uncertainties of their measurements, and others may overestimate measurement reproducibility.
Geochimica et Cosmochimica Acta | 2003
S. Merchel; Ulrich Ott; S. Herrmann; Bernhard Spettel; T. Faestermann; K. Knie; G. Korschinek; G. Rugel; A. Wallner
Abstract We have developed a procedure that allows extraction of clean nanodiamond samples from primitive meteorites for isotopic analyses of trace elements on a timescale of just a week. This procedure includes microwave digestion and optimization of existing isolation techniques for further purification. Abundances of trace elements that are difficult to dissolve using standard procedures (e.g., Ir) are lower in the diamond residues prepared using the new technique. Accelerator mass spectrometry (AMS) was explored as a means for isotopic measurements. Results obtained on diamond fractions from Allende and Murchison show the need for suitable matrix-adjusted standards to correct for fractionation effects; nevertheless they allow putting an upper limit on the abundance of 198Pt-H in nanodiamonds of ∼1 × 1014 atoms/g. This limit is on the order of what can be expected from predictions of competing nucleosynthesis models and extrapolation of the apparently mass dependent abundance trend of the associated noble gases. Unfortunately, and unexpectedly, presolar silicon carbide is almost quantitatively dissolved during microwave digestion with HCl/HF/HNO3. Re-evaluation of the standard extraction technique, however, shows that it also may lead to severe loss of fine-grained SiC, a fact not commonly appreciated. A lower limit to SiC abundance in Murchison is 20 ppm, and previous conclusions that Murchison SiC is unusually coarse-grained compared to SiC in other primitive meteorites seem not to be warranted. Graphite and silicon nitride may survive and possibly can be separated after this step as suggested by a simulation experiment using terrestrial analog material, but the detailed behavior of meteoritic graphite requires further study.
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 2000
S. Merchel; T. Faestermann; U. Herpers; K. Knie; G. Korschinek; Ingo Leya; R. Michel; G. Rugel; C. Wallner
Abstract Integral cross sections of the nuclear reactions nat Fe(p,x) 53 Mn, nat Ni(p,x) 53 Mn and nat Ni(p,x) 60 Fe up to proton energies of 2.6 GeV were measured by means of accelerator mass spectrometry. Additionally, elemental production rates from targets placed in an isotropically irradiated iron sphere were determined. They provide the basis to calculate the corresponding neutron-induced cross sections. Both types of nuclear data are needed for the calculation of depth- and size-dependent production rates of the long-lived cosmogenic radionuclides, which gives us the possibility to discuss experimental abundances of 53 Mn and 60 Fe in extraterrestrial matter.
Meteoritics & Planetary Science | 1998
A. Bischoff; Damian Weber; Robert N. Clayton; T. Faestermann; I. A. Franchi; U. Herpers; K. Knie; G. Korschinek; P. W. Kubik; Toshiko K. Mayeda; S. Merchel; R. Michel; S. Neumann; H. Palme; C. T. Pillinger; L. Schultz; A. S. Sexton; Bernhard Spettel; A. B. Verchovksy; H. W. Weber; G. Weckwerth; D. Wolf
Meteoritics & Planetary Science | 2005
Ulrich Ott; M. Altmaier; U. Herpers; J. Kuhnhenn; S. Merchel; R. Michel; R. K. Mohapatra
Physical Review B | 2006
P. Bernhard; J. Maul; T. Berg; F. Wegelin; Ulrich Ott; Ch. Sudek; H. Spiecker; S. Merchel; G. Schönhense
Meteoritics & Planetary Science | 1999
K. Knie; S. Merchel; G. Korschinek; T. Faestermann; U. Herpers; M. Gloris; R. Michel
Archive | 2001
Ulrich Ott; M. Altmaier; U. Herpers; J. Kuhnhenn; S. Merchel; R. Michel; R. K. Mohapatra
EPIC3PAST Gateways, Third International Conference and Workshop, Alfred Wegener Institute Potsdam, 2015-05-18-2015-05-22Terra Nostra 2015/1, S. 38, GeoUnion Alfred-Wegener-Stiftung | 2015
Diedrich Fritzsche; Thomas Opel; Hanno Meyer; S. Merchel; G. Rugel; S.M. Enamorado Baez
Archive | 2000
S. Merchel; M. Altmaier; T. Faestermann; U. Herpers; K. Knie; G. Korschinek; P. W. Kubik; S. Neumann; R. Michel; M. Suter