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Two-photon decay of the single K-shell-hole state in mercury

Measurements of two-photon decay of the single K-shell-hole state in mercury have been made. The decay of radioactive 201Tl was used to generate the single-hole states. The radioactive source was placed between two planar germanium detectors in a close 1800 geometry. Pulses from the detectors were fed into a three-dimensional (128*512*512)-channel pulse-height analyzer and recorded in a PC. Two-dimensional E1-E2 energy spectra have been made from the records of coincidence data. The continuous spectra along the sum-energy lines E1 + E2 = transition energy, corresponding to the two-photon transitions of the 2s, 3s, 3d and 4sd electrons to the 1s single-hole, have been derived. The 2s &reg ; 1s spectrum shows a broad maximum at mid-energy. The 3s &reg ; 1s spectrum is similar but of smaller transition probabilities. The 3d &reg ; 1s spectrum is very strong and shows a minimum at mid-energy, increasing steadily up to the resonance corresponding to the 3d &reg ; 2p &reg ; 1s cascade of L and K X-rays. The 4sd &reg ; 1s spectrum is similar to the 3d &reg ; 1s spectrum, but of lesser intensity. The spectra have been fitted by the non-relativistic transition probablilites derived using hydrogen-like wave functions (V. Florescu et al., Phys. Rev. A 36, 2155 (1987)), modified for realistic energies of K and L X-ray transitions and radiation damping. Shapes of the spectra are fairly well reproduced.

two-photon decay; transitions of the 2s; 3s; 3d and 4sd electrons to the 1s single-hole; non-relativistic transition probablilites

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