A new list of thorium and argon spectral lines in the visible

Aims. We present a new list of thorium and argon emission lines in the visible obtained by analyzing high-resolution (R=110,000) spectra of a ThAr hollow cathode lamp. The aim of this new line list is to allow significant improvements in the quality of wavelength calibration for medium- to high-resolution astronomical spectrographs. Methods. We use a series of ThAr lamp exposures obtained with the HARPS instrument (High Accuracy Radial-velocity Planet Searcher) to detect previously unknown lines, perform a systematic search for blended lines and correct individual wavelengths by determining the systematic offset of each line relative to the average wavelength solution. Results. We give updated wavelengths for more than 8400 lines over the spectral range 3785-6915 A. The typical internal uncertainty on the line positions is estimated to be ~10 m/s (3.3 parts in 10^8 or 0.18 mA), which is a factor of 2-10 better than the widely used Los Alamos Atlas of the Thorium Spectrum (Palmer & Engleman 1983). The absolute accuracy of the global wavelength scale is the same as in the Los Alamos Atlas. Using this new line list on HARPS ThAr spectra, we are able to obtain a global wavelength calibration which is precise at the 20 cm/s level (6.7 parts in 10^10 or 0.0037 mA). Conclusions. Several research fields in astronomy requiring high-precision wavelength calibration in the visible (e.g. radial velocity planet searches, variability of fundamental constants) should benefit from using the new line list.Comment: 7 pages, 6 figures, accepted for publication in A&

Precise Determination of the Li7(p,α)He4 and Be9(d,α)Li7 Q-Values

A magnetic spectrograph of the double-focusing 180° sector type has recently been constructed in this laboratory and used to measure the energy release in the Li7(p,α)He4 reaction

Cross sections and Q-values for the C13+D2 reactions

The energy of the reaction products from the disintegration of C13 by deuterons has been analyzed with the 16" double-focusing magnetic spectrometer. The emitted particles, identified by their mv/Ze value and pulse size in the scintillation proportional counter, correspond to the reactions (1) C13(d,α)B11, (2) C13(d,p)C14, and (3) C13(d,t)C12

Highly Excited States in C11. Elastic Scattering of Protons by B10

Excitation functions for the elastic scattering of protons by B10 have been measured at center-of-mass scattering angles near 90°, 125°, and 160° for proton energies between Ep=0.15 MeV and Ep=3.0 MeV. Scattering angular distributions were measured at 43 selected energies in this range. An excitation function for the reaction B10(p, α0)Be7 was also measured between Ep=1.5 MeV and Ep=2.6 MeV at a laboratory angle of 90°. The atomic stopping cross section of boron for protons has been determined between Ep=0.1 MeV and Ep=3.0 MeV. The elastic scattering excitation functions exhibit conspicuous anomalies at Ep=1.50 MeV and Ep=2.180 MeV. The α0 transition to the ground state of Be7 is also resonant at Ep=2.180 MeV. The behavior of the cross sections in these regions has been analyzed in terms of compound states of C11. Satisfactory agreement is achieved with level assignments of Jπ=7/2+ with ER=1.50 MeV, Γp=90 keV, ΓT=250 keV; and Jπ=9/2+ with ER=2.180 MeV, Γp=100 keV, Γα0=100 kev, and ΓT=200 keV. Although complete analysis of the scattering is hindered by the influence of unknown background processes, the negative parity assignment for the previously reported state at Ep=1.17 MeV, derived from other reaction experiments, appears inconsistent with the scattering

Argon I lines produced in a hollow cathode source, 332 nm to 5865 nm

We report precision measurements by Fourier transform spectroscopy of the vacuum wavenumber, line width, and relative signal strength of 928 lines in the Ar I spectrum. Wavelength in air and classification of the transition are supplied for each line. A comparison of our results with other precision measurements illustrates the sensitivity of Ar I wavelengths to conditions in the light source

Physiological effects of environmental acidification in the deep-sea urchin <i>Strongylocentrotus fragilis</i>

Anthropogenic CO₂ is now reaching depths over 1000 m in the Eastern Pacific, overlapping the Oxygen Minimum Zone (OMZ). Deep-sea animals are suspected to be especially sensitive to environmental acidification associated with global climate change. We have investigated the effects of elevated <i>p</i>CO₂ and variable O₂ on the deep-sea urchin <i>Strongylocentrotus fragilis</i>, a species whose range of 200–1200 m depth includes the OMZ and spans a <i>p</i>CO₂ range of approx. 600–1200 μatm (approx. pH 7.6 to 7.8). Individuals were evaluated during two exposure experiments (1-month and 4 month) at control and three levels of elevated <i>p</i>CO₂ at in situ O₂ levels of approx. 10% air saturation. A treatment of control <i>p</i>CO₂ at 100% air saturation was also included in experiment two. During the first experiment, perivisceral coelomic fluid (PCF) acid-base balance was investigated during a one-month exposure; results show <i>S. fragilis</i> has limited ability to compensate for the respiratory acidosis brought on by elevated <i>p</i>CO₂, due in part to low non-bicarbonate PCF buffering capacity. During the second experiment, individuals were separated into fed and fasted experimental groups, and longer-term effects of elevated <i>p</i>CO₂ and variable O₂ on righting time, feeding, growth, and gonadosomatic index (GSI) were investigated for both groups. Results suggest that the acidosis found during experiment one does not directly correlate with adverse effects during exposure to realistic future <i>p</i>CO₂ levels

Masses of Light Nuclei from Nuclear Disintegration Energies

Values of the atomic masses from n^1 to F^(20) have been derived from the Q-values of nuclear reactions with a procedure of statistical adjustment. Tables are given of several fundamental mass differences, the most probable Q-values, and the atomic masses. Some disparity with the mass spectroscopic results is noted

Argon I lines produced in a hollow cathode source, 332 nm to 5865 nm

We report precision measurements by Fourier transform spectroscopy of the vacuum wavenumber, line width, and relative signal strength of 928 lines in the Ar I spectrum. Wavelength in air and classification of the transition are supplied for each line. A comparison of our results with other precision measurements illustrates the sensitivity of Ar I wavelengths to conditions in the light source