Isotopic compositions of the elements 1997 (Technical Report)

Rosman, K.J.R.; Taylor, Philip

doi:10.1351/pac199870010217

Cited by 901 publications

(489 citation statements)

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“…For the second, parameter choices were optimized in the present work for the nuclei of immediate relevance of the reactions studied, together with their immediate neighbors (local approach), respecting known Z and A dependences and the available experimental information. (5) a Isotopic composition taken from [14]. b Isotopic composition taken from data sheet received from JAERI.…”

Section: Introductionmentioning

confidence: 99%

“…Here, a comparison between the local approach and the global approach is a comparison between the modified geometrydependent hybrid model and the two-component exciton model. Since multistep processes are very important also at intermediate energies, e.g., for the prediction of cross sections needed for development of accelerator-driven systems [8,9], the improvement of both experimental and theoretical PE knowledge in the range [14][15][16][17][18][19][20][21] MeV is of certain interest.…”

Section: Introductionmentioning

confidence: 99%

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Reaction mechanisms of fast neutrons on stable Mo isotopes below 21 MeV

et al. 2005

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A large number of new measurements with the activation technique were performed for (n,2n) and neutron-induced Z = 1,2 reaction cross sections on the stable molybdenum isotopes in the energy range from 13.5 to 21 MeV. First results were obtained for the 92 Mo(n,2n) Mo(n,x) 97 Nb m , and 100 Mo(n,α) 97 Zr reactions, above 16 MeV. A significant number of high-accuracy 14 MeV measurements were performed which are in good agreement with the measurements above 16 MeV for reactions studied in both energy ranges. The rather complete database for the molybdenum isotopes was analyzed with two different sets of consistent model calculations: a local and a global approach. The global approach (a blind calculation with the TALYS code) provides a good overall description of the dominant reaction channels, although the (n,α) reactions for the heavy isotopes are overpredicted. The local approach (an adjusted calculation with the STAPRE-H code) describes the shapes and magnitudes of the excitation functions well from the reaction thresholds up to 21 MeV using a consistent parameter set, which was optimized based on all experimental information for the nuclei at hand and their immediate neighbors. The agreement between experimental and calculated data is, in general, good both at the maxima and at the tails of the excitation functions, and both for total activation cross sections of a particular channel and for cross sections leading to isomers, showing the viability of the level densities, the optical models, and the γ widths. Comparison of the two model calculations with the data indicates the relevance of an appropriate treatment for preequilibrium (PE) α-particle emission for the description of the data above 14 MeV. Comparison between the model calculations shows largely different PE deuteron emission contributions to the total ( Z = 1, A = 1) cross sections with an additional marked difference in energy dependence. This suggests that emission spectra around 20 MeV are required to establish the magnitude of the PE deuteron emission contribution to this process. New γ -ray strength functions were established by verification against average (n,γ ) data and were demonstrated to give good agreement with the measured isomer production cross sections.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reaction mechanisms of fast neutrons on stable Mo isotopes below 21 MeV

et al. 2005

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“…An overview of the isotopic composition and average masses are given in the IUPAC tables, which are updated on a regular basis. 103 For quantification by external calibration with total combined uncertainties of several percent (mainly influenced by repeatability, blank and calibration), the natural variation is, certainly in most cases, negligible. For quantification by isotope dilution, these variations have to be taken into account only for a limited number of elements (e.g., Pb).…”

Section: Mass Fractionation Effects and Isotopic Variationsmentioning

confidence: 99%

Inductively coupled plasma- and glow discharge plasma-sector field mass spectrometry : Part I. Tutorial: Fundamentals and instrumentation

Jakubowski

Prohaska

Rottmann

et al. 2011

J. Anal. At. Spectrom.

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The aim of this series of two reviews is to introduce the basic concepts of ICP and GD sector field instruments, to discuss their peculiarities and performance, to present selected analytical applications for demonstration of the 'state of the art' and, finally, to identify possible future trends and developments. Part I focuses on fundamentals, instrumentation and operation of instruments to give an overview of the capabilities of the actual commercially available instrumentation, whereas selected applications will be discussed in detail in part II.

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“…When using these components in our spectral synthesis, we divide out the solar system isotopic ratios as given by Rosman & Taylor (1998), but we stress that this step is not included in the data presented here. Notes.- Table 5 is published in its entirety in the electronic edition of the Astrophysical Journal.…”

Section: Appendix C Hyperfine Component Data For Neodymiummentioning

confidence: 99%

Europium, Samarium, and Neodymium Isotopic Fractions in Metal‐Poor Stars

Roederer¹,

Lawler²,

Sneden³

et al. 2008

AIP Conference Proceedings

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We have derived isotopic fractions of europium, samarium, and neodymium in two metal-poor giants with differing neutron-capture nucleosynthetic histories. These isotopic fractions were measured from new high-resolution (R $ 120;000), high signal-to-noise ratio (S/N $ 160Y1000) spectra obtained with the 2d-coudé spectrograph of McDonald Observatory's 2.7 m Smith telescope. Synthetic spectra were generated using recent high-precision laboratory measurements of hyperfine and isotopic subcomponents of several transitions of these elements and matched quantitatively to the observed spectra. We interpret our isotopic fractions by the nucleosynthesis predictions of the stellar model, which reproduces s-process nucleosynthesis from the physical conditions expected in low-mass, thermally pulsing stars on the AGB, and the classical method, which approximates s-process nucleosynthesis by a steady neutron flux impinging on Fe-peak seed nuclei. Our Eu isotopic fraction in HD 175305 is consistent with an r-process origin by the classical method and is consistent with either an r-or an s-process origin by the stellar model. Our Sm isotopic fraction in HD 175305 suggests a predominantly r-process origin, and our Sm isotopic fraction in HD 196944 is consistent with an s-process origin. The Nd isotopic fractions, while consistent with either r-process or s-process origins, have very little ability to distinguish between any physical values for the isotopic fraction in either star. This study for the first time extends the n-capture origin of multiple rare earths in metal-poor stars from elemental abundances to the isotopic level, strengthening the r-process interpretation for HD 175305 and the s-process interpretation for HD 196944.

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Isotopic compositions of the elements 1997 (Technical Report)

Cited by 901 publications

References 2 publications

Reaction mechanisms of fast neutrons on stable Mo isotopes below 21 MeV

Reaction mechanisms of fast neutrons on stable Mo isotopes below 21 MeV

Inductively coupled plasma- and glow discharge plasma-sector field mass spectrometry : Part I. Tutorial: Fundamentals and instrumentation

Europium, Samarium, and Neodymium Isotopic Fractions in Metal‐Poor Stars

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