Propagation of Neutron Cross Section, Fission Yield, and Decay Data Uncertainties in Depletion Calculations

Propagation of nuclear data uncertainties in reactor calculations is interesting for design purposes and libraries evaluation. Previous versions of the GRS XSUSA library propagated only neutron cross section uncertainties. We have extended XSUSA uncertainty assessment capabilities by including propagation of fission yields and decay data uncertainties due to the their relevance in depletion simulations. We apply this extended methodology to the UAM6 PWR Pin-Cell Burnup Benchmark, which involves uncertainty propagation through burnup.

Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter

Context. Chromospheric activity produces both photometric and spectroscopic variations that can be mistaken as planets. Large spots crossing the stellar disc can produce planet-like periodic variations in the light curve of a star. These spots clearly affect the spectral line profiles, and their perturbations alter the line centroids creating a radial velocity jitter that might “contaminate” the variations induced by a planet. Precise chromospheric activity measurements are needed to estimate the activity-induced noise that should be expected for a given star. Aims. We obtain precise chromospheric activity measurements and projected rotational velocities for nearby (d ≤ 25 pc) cool (spectral types F to K) stars, to estimate their expected activity-related jitter. As a complementary objective, we attempt to obtain relationships between fluxes in different activity indicator lines, that permit a transformation of traditional activity indicators, i.e., Ca II H & K lines, to others that hold noteworthy advantages. Methods. We used high resolution (~50 000) echelle optical spectra. Standard data reduction was performed using the IRAF ECHELLE package. To determine the chromospheric emission of the stars in the sample, we used the spectral subtraction technique. We measured the equivalent widths of the chromospheric emission lines in the subtracted spectrum and transformed them into fluxes by applying empirical equivalent width and flux relationships. Rotational velocities were determined using the cross-correlation technique. To infer activity-related radial velocity (RV) jitter, we used empirical relationships between this jitter and the R’_HK index. Results. We measured chromospheric activity, as given by different indicators throughout the optical spectra, and projected rotational velocities for 371 nearby cool stars. We have built empirical relationships among the most important chromospheric emission lines. Finally, we used the measured chromospheric activity to estimate the expected RV jitter for the active stars in the sample.

Catalogue of bright stars, containing all important data known in June, 1930, relating to all stars brighter than 6.5 visual magnitude, and to some fainter ones.

At head of title: Yale university observatory.

The peak of the load; the waiting months on the hilltop from the entrance of the Stars and Stripes to the second victory of the Marne.

Mode of access: Internet.

A catalogue of 1625 stars between 39o and 41o South declination for the equinox 1900-0 selected as reference points for the Astrographic catalogue,

T.p. missing.

Symmetry of neutron induced U²³⁵ fission at individual resonances : final report /

Prepared for U.S. Atomic Energy Commission.

A review of analytical methods for the calculation of neutron and gamma-ray attenuations /

"October 5, 1949."

Technical impediments to a more effective utilization of neutron transmutation doped silicon for high-power device fabrication /

"Issued May 1980."

New general catalogue of double stars within 120⁰ of the North pole...

Accompanied by "List of corrections to the New general catalogueof double stars within 120⁰ of the North pole, by Robert Grant Aitken." (7 p.30 x 23 cm.) Published: [Washington] 1934.

The influence of the stars : a book of old world lore /

Mode of access: Internet.

First Melbourne general catalogue of 1227 stars for the epoch 1870 : deduced from observations extending from 1863 to 1870 /

Mode of access: Internet.

Observations of double stars made at the United States naval Observatory. [1875-1891]

Mode of access: Internet.

Ptolemy's Tetrabiblos, or Quadripartite: being four books of the influence of the stars.

Plate wanting.

The new American grammar of the elements of astronomy, on an improved plan: in three books. I. The use of the terrestrial globe in the solution of geographical and astronomical problems. II. The use of the celestial globe in the solution of problems, relative to the sun, planets, and fixed stars. III. The solar system, and the firmament of fixed stars. The whole systematically arranged and scientifically illustrated; with several cuts and engravings; and adapted to the instruction of youth in schools and academies.

Mode of access: Internet.