Directional correlation between α particles andLx rays in the decay ofPu238and

Abstract

Anisotropy in the directional correlation of nuclear radiations and L x rays has been clearly identified for the first time. L3 x-ray groups, LI and La, are observed to be directionally correlated with a particles in the decays of Pu and Cm. The ratio of anisotropy for LI and La is consistent with the recent observation that LI has a much greater admixture of M2 than predicted by relativistic calculations.Several attempts to demonstrate directional correlation between nuclear radiations and L x rays have been reported [1-8]. Anisotropy has not been clearly established in any of these studies. Most recently, Bargholtz et al. [8] reported statistical evidence of a very small directional correlation between y rays and La in the decay of ' Tb. The ratio of directional correlation of the Lt and La groups was interpreted as being anomalous. The results are inconclusive and difficult to explain.Directional correlations between nuclear radiations in cascade in nuclear deexcitation (e.g. , radioactive decay) are well understood [9], as are the directional correlations between x rays in cascade in atomic deexcitation [10].The directional correlation between nuclear radiations and x rays in cascade has received less attention. Dolginov [11] gave a theoretical description of the correlation between nuclear radiations and x rays; however, with little experimental data available for comparison, the theory remains largely untested. Only cascades in which the intermediate states have total angular momentum J ) -, ' allow anisotropic directional correlation. Consequently the most tightly bound subshell that is expected to support anisotropic directional correlation is the Li(2p3I2) subshell. The L x-ray spectrum cannot be fully resolved, but falls into four groups of lines that can be resolved. Lt and La groups are due to the transitions L3 Mt and L3 M45, respectively, and therefore are expected to show if directional correlation is present. LP is due to transitions from all subshells thus diluting any directional correlation, while Ly is due to transitions from the Lt (2stiq) and L2 (2ptlq) subshells and should be isotropically distributed relative to nuclear emissions as should x-rays from the K (ls &I2) shell. However, Khalil [12] has described J )1 admixtures into the K (1s&I2) shell of atoms with highly deformed nuclei which contribute to anisotropic directional correlation between y rays and K x rays in the decay of ' 'Ta. The anisotropic angular distribution of L3 x rays of Th and U following proton ionization has recently been used by Papp et al. [13] to demonstrate deficiencies in the theoretical description of Scofield [14] of the multipolarity of LI. In the present work, the directional correlation between a particles and L x rays in the decays of Pu and Cm arises predominantly from the triple cascade; a decay to the first excited state of the daughter nucleus followed by internal conversion of an E2 electromagnetic transition and x-ray emission: nuclear angular momentum atomic angular momentum 6 e-0+ 2+ 0+ X 0 3/2

Deviation from the single-particle model in the angular distribution of thoriumL3x rays in proton-impact ionization

“…Similar to earlier studies [9,11,37] the present analysis shows that the anisotropy of various E1-allowed transitions deviates from the theoretical calculations carried out using the independent-particle model. The ratios of the anisotropy parameters are expected to be independent of the ionization process; however, they showed a dependence on the proton energy.…”

Alignment of atomic inner-shells following alpha-decay-induced ionization

“…The initial condition on R α reflects the fact that high-energy alpha particles, escaping from the nucleus will not have to tunnel as far as lower energy particles to overcome the potential barrier. For this reason, there is an inverse final velocity dependence of the initial condition on R α in equation (5). By inserting equation ( 5) into the Hamiltonian, we may write amplitude (1) as…”

“…Therefore, the analysis of the angular and polarization properties of these x-ray lines may reveal important information on the dynamics of inner-shell vacancy production as well as the relativistic and multi-pole mixing effects of bound-bound transitions not normally resolvable in total decay rates. An abundance of experimental work on x-ray radiation due to electronic deexcitation into L III shell vacancies (for which j = 3/2) has already been reported [1][2][3][4][5][6][7][8]. To this point, the methods of vacancy production employed in these works were limited to the traditional techniques of ion/electron-atom collision or photo-ionization.…”