Wavelengths and lifetime measurements in He-like Cr XXIII and Li-like Cr XXII

Abstract

Two and three electron spectra have been investigated in a beam-foil experiment with a chromium ion beam at 7 MeV/amu. The He-like Cr XXIII (Cr 22+) 3 S 1 - 3 P 2 transition is measured at 325.36±0.5 A, giving a transition energy of 307350 (360) cm −1 ; this value is compared to the theoretical values given by De Serio et al. [1] and Hata and Grant [2]. A higher accuracy would be needed to provide a good test of the two-electron QED effects. The Li-like Cr XXII (Cr 21+) 2 S 1/2 - 2 P 3/2 transition is found at 222.97±0.05 A leading to a transition energy of 448490 (102) cm −1 in very good agreement both with previous measurements in a tokamak plasma [9] and with theoretical predictions [3, 13b] Etude par la methode faisceau-feuille avec des ions de Cr de 7 MeV/uma: longueur d'onde de la raie 3 S 1 - 3 P 2 de Cr XXIII et 2 S 1/2 - 2 P 3/2 de Cr XXII. Comparaison aux donnees theoriques. Determination des durees de vie