High-current hollow-cathode source as a radiant intensity standard in the 40-125-nm wavelength range.
The radiant intensity of VUV emission lines of a high-current hollow-cathode source has been determined for the 40-125-nm spectral range. The source is operated at a constant current of 1 A with an aluminum cathode. Different rare gases are alternatively used as the buffer gas at pressures of ~100 Pa. The radiant intensity has been determined by comparison with the calculable spectral radiant flux of the electron storage ring BESSY. Radiant intensities of the emission lines are in the 7-1400-µW/sr range. The long-term reproducibility of the radiant intensity of the source is within ±10% (2σ value). The systematic uncertainty of the radiometric calibration is better than 9% (√32σ value).
Absolute intensity calibration of the Wendelstein 7-X high efficiency extreme ultraviolet overview spectrometer system.
The new high effiency extreme ultraviolet overview spectrometer (HEXOS) system for the stellarator Wendelstein 7-X is now mounted for testing and adjustment at the tokamak experiment for technology oriented research (TEXTOR). One part of the testing phase was the intensity calibration of the two double spectrometers which in total cover a spectral range from 2.5 to 160.0 nm with overlap. This work presents the current intensity calibration curves for HEXOS and describes the method of calibration. The calibration was implemented with calibrated lines of a hollow cathode light source and the branching ratio technique. The hollow cathode light source provides calibrated lines from 16 up to 147 nm. We could extend the calibrated region in the spectrometers down to 2.8 nm by using the branching line pairs emitted by an uncalibrated pinch extreme ultraviolet light source as well as emission lines from boron and carbon in TEXTOR plasmas. In total HEXOS is calibrated from 2.8 up to 147 nm, which covers most of the observable wavelength region. The approximate density of carbon in the range of the minor radius from 18 to 35 cm in a TEXTOR plasma determined by simulating calibrated vacuum ultraviolet emission lines with a transport code was 5.5x10(17) m(-3) which corresponds to a local carbon concentration of 2%.
5.63 and 5.80 MeV levels of Ne20; de-excitation branching
Abstract The ratio Г γ /Г for the 5.63 and 5.80 MeV levels of Ne 20 has been determined to be 0.077 (±0.008) and −4 , respectively, by using the C 12 (C 12 , α)Ne 20 reaction and determining the fraction of the events in which the alpha-particle and the Ne 20 recoil are present in coincidence at the kinematically correct angles. In both cases these results in themselves are shown to imply radiative E1 transition (5.63→1.63 and 5.80→0, respectively) probabilities ⪡5 × 10 −5 Weisskopf units. When taken together with the life-time for the 5.63 MeV level measured by Evans et al . values of Г( E1 ) ≲ 5 × 10 −6 and Г α ≈ 6% of the particle estimate are obtained for this state.