E1 Transition Matrix Elements Research Articles

E1 and M1 transition strengths from two-quasiparticle structures in 168Er

Lifetime measurements in 168Er were performed in the (n, γ) reaction using the generalized centroid-shift method with the following results: T 1 2 (JK π = 54 − at 1193.0 keV) = 0.70±0.07 ns and T 1 2 (JK π = 33 3 − at 1999.2 keV) = 0.44 −0.08 +0.12 ns . The size of some matrix elements of the ty 〈0 +| M 10 E |0 −〉(Δ K = 0) and 〈0 +| M 1−1 E|1 −〉(ΔK = 1) in 168Eris estimat The evolution of the strenghts of E1 transitions linking some negative-parity bands with the ground band in N = 100 isotones with varying spin and neutron number is considered. For K-forbidden transitions, ΔK = 0 admixtures in the E1 matrix elements are found to be dominant in 168Er and 170Yb, while in 174W ΔK = 1 admixtures become at least similarly important. In 168Er, K π = 2 γ + admixtures in the ground band appear responsible for up to 45% of the size of the E1 transition matrix elements. A surprisingly small mixing (∼0.01%) of the structure { 7 2 −[523]− 1 2 +[411]} p (K π = 3 3 − ) into the s 7 2 +[633]− 1 2 −[5]} n(K π = 3 1 − ) and vice versa is found to account for the measured B(M1 strenght of the band-head 33 3 − → 33 1 − transition.

A semi-empirical evaluation of parity non-conserving E1 transitions in thallium

The authors apply their previously-developed semi-empirical potential method in the calculation of the dominant high order many-body correlation effects in thallium which can be modelled by a central potential. The authors use this method to evaluate the thallium parity non-conserving electric dipole 6p1/2 to 7p1/2 and the 6p1/2 to 6p3/2 transitions. To estimate the accuracy of the calculation the authors also calculate the parity conserving E1 transition matrix elements and the hyperfine interaction constants. For the 6p1/2 to 7p1/2 parity non-conserving transition the authors obtain -7.97*10-11 (1+or-0.07) (-iea0QW/N) and for the 6p1/2 to 6p3/2 parity non-conserving transition -31.6*10-11 (1+or-0.09) (-iea0QW/N).

A semi-empirical approach to the calculation of parity non-conserving E1 transition matrix elements in caesium

In this paper the authors describe a semi-empirical, approach for calculating certain high-order perturbation effects in a simple manner. They use these modified orbitals in RPA type equations to give values for E1 transition matrix elements and hyperfine dipole constants that agree well with experiment. Including the spin-independent weak interaction leads to parity non-conserving equations. For the caesium 6s12/ to 7s1/2 parity non-conserving E1 transition they obtain 0.904(1+or-0.02)*10-11 (-iea0Qw/N).

Relativistic many-body perturbation theory of parity non-conservation in heavy atoms

The effect of residual many-electron interactions on the parity non-conservation in heavy atoms due to the nuclear spin-independent part of the weak neutral current interaction is calculated. The special feature of the method is the inclusion of the parity non-conserving term in the zeroth-order single-particle Hamiltonian. The basic single-particle states are eigenstates of angular momentum but not parity. Standard many-body perturbation methods are used to derive diagrammatic expressions for the resulting parity non-conserving E1 transition matrix elements. Some simplifying theorems are proved and the method for evaluating the zeroth- and first-order diagrams is outlined.

Hexadecapole deformations and E1 transitions in odd-A Ho and Tm nuclei

The experimental B(E1) values of transition 7/27/2+(404) to or from 7/27/2-(523) in 161,163,165Ho and 163,165,167,169,171Tm reveal characteristic minima in both groups of isotopes. E1 transition matrix elements are calculated on the basis of a Nilsson model including recently-deduced values of the deformation parameters epsilon 2 and epsilon 4. If these theoretical epsilon 4 values are arbitrarily decreased by a constant value, an improved degree of agreement with experiment can be obtained.

Parity-violating circular dichroism in atomic caesium (neutral currents)

The parity-violating E1 transition matrix elements between the 6s and 7s states of atomic Cs to be expected on the basis of the Weinberg-Salam model of neutral weak currents has been calculated. It is found that iE16s,7s=3.60*10-11 atomic units, in excellent agreement with a calculation by Bouchiat and Bouchiat (1975) using a different method.