Eur. Phys. J. A (2009) 39: 341-348
https://doi.org/10.1140/epja/i2008-10714-3

Regular Article - Theoretical Physics

Prospect of triggering the ^178m2Hf isomer and the role of resonance conversion

¹ Fock Institute of Physics, St. Petersburg State University, 198904, St. Petersburg, Russia
² Petersburg Nuclear Physics Institute, 188300, Gatchina, Russia
³ Department of Physics, Harbin Institute of Technology, 150001, Harbin, China

^* e-mail: trzhask@thd.pnpi.spb.ru

Received: 5 June 2008
Revised: 27 December 2008
Accepted: 27 December 2008
Published online: 13 February 2009

Abstract

A mechanism of triggering the 12.7keV E3 transition, based on the new decay mode of the 31y isomer via resonance internal conversion and emission of a 1.4keV X-ray quantum, is considered. Actually, this decay mode was observed previously in the decay of 45- and 46-fold ions of ¹²⁵Te . For the purpose of triggering, the atomic radiative vertex has to be induced by resonance radiation. This mechanism makes triggering by an order of magnitude more efficient than triggering a bare nucleus, and is achieved at a lower combination frequency. An experiment is proposed for the direct observation of the new decay mode. This also offers a new way of resonance scattering of these X-rays. Triggering through higher-lying 2573 and 2805keV states is also considered. The results are extended to the general problem of triggering. The main obstacle for enhancing the efficiency is a high internal conversion rate. For this reason, shape isomers with low multipole order --E1 , M1 , and with a high enough energy of triggering transition are of interest for triggering. The partial ionization of the outer electrons will also help. The same recommendations hold for triggering isomers in laser-produced plasma.