Beam-Foil Based Efficiency Calibration of a Grazing-Incidence Spectrometer

Abstract

Foilexcitation at tandem energies has been used to produce 4electron ions of Mg, Al, Si, P and S. Decay curves of the 2r2-2s2p and 2s2p-2p2 singlet transitions have been obtained. The lifetimes extracted are in good agreement with calculations by Victorov and Safronova. Relative spectrometer efficiencies in the wavelength range 25-75 nm have been derived from a comparison of the intensities of the 2s2p-2p2 transitions and their subsequent appearance as cascades in the decay of the 2s2p 'Po level. The observation of a smooth radiation continuum from a solid target bombarded with slow heavy ions justifies a smooth interpolation between the discrete calibration wavelengths.

Calcium and Potassium Spectra in the EUV

“…The K VII 3s 2 3p 2 P o 1/2,3/2 -3s3p 2 2 P 1/2,3/2 multiplet has four components, with expected relative intensities of 10, 20, 40, and 20 [17], in the sequence of increasing wavelength. The spectrometer efficiency curve is practically flat over this interval [43,44], and the observation closely matches the predicted line ratios. The uncertainty of the line ratios in this measurement is dominated by counting statistics; the amplitude of the weak component is determined to within about 8%, and that of the strong component to within about 4%.…”

“…A slit width of 50 µm (80 µm) resulted in a line width (FWHM) of 0.035 nm (0.06 nm). The detection efficiency function of the spectrometer favoured the wavelength range near λ ≈ 20 nm, but permitted measurements up to and even beyond 60 nm [43,44]. More details and other spectrum samples can be found in References [3,4].…”

“…These transitions between levels of maximum angular momentum (known as yrast transitions in nuclear physics) are often prominent in beam-foil spectra, because the decays of many high-n, high-levels are funnelled through such transitions. Another few weak lines appear in the wavelength range 67-75 nm where the spectrometer efficiency is rather low[43,44]. The line group at 74.5 nm is likely the K X (Ne-like) 5g-6h transition…”

Beam-foil excitation studies of hydrogen-like ions

“…These lines are located in the wavelength interval 23.7 to 30.4 nm. Recently, a relative intensity calibration of the present set-up has been obtained for wavelengths between 25 and 75 nm [28]. Slightly extrapolating this calibration and using the relative line intensities mentioned above, with corrections for the finite width of the detection window, we find…”

MCDHF Calculations and Beam-Foil EUV Spectra of Boron-Like Sodium Ions (Na VII)

“…Figure 2 shows the complete spectral range that was covered in sections and the individual spectra stitched together. An approximate response function of the spectrometer-detector combination has been established (a decade earlier) for the wavelength range above 20 nm [76,77], but the measured spectrum (recorded in sections at various occasions and having varying signal normalization settings) has not been corrected for this. Nevertheless, one has to be aware of the general efficiency function that in this case has a wide maximum near a wavelength of 20 nm and falls off monotonically to half of that efficiency at wavelengths shorter than 12 nm or longer than 40 nm.…”