Metastable ion lifetime studies utilizing a heavy-ion storage ring: Measurements onBe−

Abstract

The measurement of long (-10 /is-100 ms) ionic autodetachment lifetimes utilizing a heavy-ion storage ring is demonstrated with 10-125 keV beams of Be". The lifetime of the metastable Be~(2s2p 24 / > 3/2) state was found to be 45 ± 5 //s, which represents an order-of-magnitude improvement in experimental accuracy over an earlier direct-beam-line experiment. This new result is a factor of 3 shorter than the recent theoretical value of 129 jus. New perspectives for storage-ring-based measurements of a variety of metastable lifetimes, both autoionizing and radiative, are briefly discussed.

Storage-ring measurement of the hyperfine-induced2s2p3P0→2sSchippers1, Bernhardt2, Müller3 et al. 2012Phys. Rev. A362300View full textAdd to dashboardCite

“…2). This effect is expected to increase quadratically with increasing magnetic field strength [27]. Since the 3% change of τ HFI is smaller than the 4% experimental uncertainty, it must, however, be concluded that there is no significant influence of the TSR magnetic fields on the measured HFI transition rates at the present level of experimental accuracy.…”

“…Experiments with singly charged In + and Al + ions [22,23] have used radiofrequency traps. The rates for the atomic-clock transitions 5s5p 3 P 0 → 5s 2 1 S 0 in 115 In + and 3s3p 3 P 0 → 3s 2 1 S 0 in 27 Al + have been measured using optical methods with uncertainties 1 of ∼4% and ∼ 7%, respectively. For Be-like N 5+ the HFI rate has been extracted from observations of a planetary nebula [24] with an uncertainty of 33%.…”

“…Generally, it must be expected that the magnetic fields in the storage-ring bending magnets lead to an additional quenching of the 2s 2p 3 P 0 state [27]. However, a recent theoretical investigation [28] concluded that this effect is negligible under the conditions of the Ti 18+ experiment.…”

Quartet and sextet states of CS−

“…9 Such long-lived negative ions can easily be detected by means of mass spectrometry and studied by radiofrequency, 10 optical 11 or laser spectroscopy. [12][13][14][15] Their lifetimes have been measured at storage ring, ion trap, or beam experiments, [16][17][18][19][20][21][22] and their electron affinities by laser photodetachment, 14,15,20,23 or autodetachment spectroscopy. 3 Detailed theoretical studies of autodetachment rates for such electronic states have mainly been performed for atoms.…”

Observation of the negative ions:Ra−,Pa−Zhao1, Nadeau2, Garwan3 et al. 1993Phys. Rev. A12190View full textAdd to dashboardCite

“…A few comments should be made about the possibility of Ra in a metastable state. The lowest excited state of Be is known to be the 2s2p P quartet [15]; its autodetachment to the ground state 2s 'S of the atom is a forbidden transition on L-S coupling, but it decays to the neutral Be ground state via the spin-orbit-induced Coulomb autodetachment with a long lifetime (the latest experimental result is 45+5 rMs [16]). Another possible excited state is 2p S which de-3982 BRIEF REPORTS cays to 2s2p P by an E1 transition.…”