Absolute measurement of the resonance lines in heliumlike vanadium on an electron-beam ion trap - art. no. 042501

Absolute measurements of the energies of resonance lines in heliumlike vana dium on an electron-beam ion trap are reported. The 1s2p P-1(1)-->1s(2), 1s 2p P-3(2)-->1s(2) (1s2p P-3(1)-->1s(2) and 1s2p P-3(0)-->1s(2)) blend and 1 s2s S-3(1)-->1s(2) transitions are 5205.10 +/- 0.14 eV, 5189.12 +/- 0.21 eV , 5180.22 +/- 0.17 eV, and 5153.82 +/- 0.14 eV, respectively. This agrees w ith recent theoretical calculations and the experimental precision lies at the same level as the current uncertainty in theory (0.1 eV). These measure ments represent a 5.7-8% determination of the QED contribution to the trans ition energies and are the most precise measurements of heliumlike resonanc e lines in the Z=19-31 range. The measurement of the 1s2s S-3(1)-->1s(2) tr ansition is also sensitive to the 1s2s S-3(1) QED contribution at the 40% l evel. The intensity of the strong 1s2p P-3(1)-->1s(2) component of the blen d compared to the total blend intensity is 94% +/- 12%. This is in accord w ith current theoretical predictions but disagrees with an earlier reported ratio.