Radiative Lifetimes and Hyperfine Induced Decay of the 1s 2p³P₂and³P₀Levels in Al XIII

Abstract

The experimental setup has been thoroughly described in [7]. The main difference is that now the radiation from the decaying levels was observed using a l m vacuum monochromator Of the Seya-"ioka type, designed and built at the The transitions ls2s 'S,-ls2p 'P2 and ls2s 'Ss,-ls2p 'Po in He-like AI have been observed in a beam-foil experiment at 900 f 1 A and 953 i: 1 A, respectively. The lifetimes of the upper levels have been determined to 5.4 i: 0.2 ns ('P2) and 4.8 i: 0.211s ("io). We have observed a shortening of the 2p 'Po lifetime in agreement with theories which consider hyperfine quenching effects, and we &'e an estimate of the quenching of the level. The wavelengths are compared with theoretical values which include Lamb shift.Uppsala Laboratory. The photons were detected with a Bendix channeltron.Step motors were used to move the grating and to translate the foil, each step corresponding to a preset vdue of integrated beam current, collected in a Faraday cup behind the foil. Typical beam currents were 200-300 nA at the 20pg cm-'

Magnetic-field- and hyperfine-induced P03−S01 transitions in Be- and Ne-like ions

“…A number of recent papers present rates of HITs [3,[12][13][14][15][16][17][18][19][20] in the absence of magnetic fields. For HIT, experimental and theoretical studies for He-like ions [21][22][23][24][25][26][27][28][29] and Ni-like Xe [15,[30][31][32] are in good agreement. The resulting rate for Be-like N by Brage et al [33], obtained by modeling of a planetary nebulae, are also in agreement with theory, albeit with fairly large experimental uncertainty.…”

Hyperfine quenching: review of experiment and theory1This review is part of a Special Issue on the 10th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas.

“…• Engström et al [7,8] made beam-foil measurements of the lifetimes of the 3 P 0 and 3 P 2 levels of the He-like ion 19 [9] carried out beam-foil measurements of lifetimes of the 3 P 0 and 3 P 2 levels of the He-like ion 25 Al at the 6.4 MV EN Tandem Accelerator in Upsala. The measured lifetime of the 3 P 0 state, where quenching contributes 30% of the total, is seen in Table 2 to be in agreement with theory.…”

“…Pioneering beam-foil measurements by Gould et al [6] on hyperfine quenching in He-like V led to many measurements [7][8][9][10][11][12][13][14][15][16][17][18][19] and theoretical calculations [20][21][22][23][24] of quenching rates along the He isoelectronic sequence. Experimental lifetimes of (1s2p) 3 P 0 states along the He isoelectronic sequence differ from theoretical lifetimes by less than 10% typically.…”

Hyperfine induced intensity redistribution in In \hbox{\sc II}

“…The calculation followed the same steps as described in section 4 except that the configuration space was created from the multi-reference configuration set 5s4f, 5s5p, 5p5d and 5d4f. Using this model the number of configurations grow rapidly, and while running the calculation with the AS4 set of orbitals some files generated by GRASP2K became larger than 2 31 bytes, and therefore too large to handle for a 32 bit program. Therefore we had to stop at the AS3 step and could not obtain certain convergence in this calculation.…”

“…Johnson et al [28] performed calculations for the whole iso-electronic sequence and Indelicato et al [29] performed calculations for all ions with Z > 40. Many lifetime measurements of the hyperfine quenched 1s2p 3 P 0 0 levels in He-like ions have also been performed, for example, in 19 F by Engström et al [30], 27 Al by Denne et al [31], 31 P by Livingston and Hinterlong [32] and in 61 Ni by Dunford et al [33].…”