Oscillator strengths and collisional damping parameters for lines of neutral calcium

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Abstract
Relative oscillator strengths for 37 lines of neutral calcium have been measured to an accuracy of +or-5% using the absorption method. The oscillator strengths are placed on an absolute scale by reference to recent lifetime measurements. All lines have lower energy levels in the range 2.5 to 3.0 eV above the ground level and the set of lines includes most of those important for the determination of the calcium abundance in late-type stars. In addition the same equipment has been used to study collisional broadening by helium of 17 lines chosen from among those with newly measured oscillator strengths. These measurements provide interesting insight into the dependence of the collisional damping parameter on total angular momentum within a spectral multiplet and on the configuration of the upper level.