Triggering of 178Hfm2 by photoinduced electron transition

• Main Author: A. Ya. Dzyublik
• Format: Article
• Language: English
• Published: Institute for Nuclear Research, National Academy of Sciences of Ukraine 2013-03-01
• Series: Âderna Fìzika ta Energetika
• Subjects: nuclear isomers; NEET; induced nuclear decay; x-rays; hafnium; nuclear spectra
• Online Access: http://jnpae.kinr.kiev.ua/14.1/Articles_PDF/jnpae-2013-14-0011-Dzyublik.pdf

We considered the NEET (nuclear excitation by electron transition) as a possible triggering mechanism of the isomer 178Hfm2 during ionization of the L3 atomic shell by x-rays. This isomer is assumed to be excited into an intermediate state by E1 electronic transition between M5 and L3 shells. Simple nonrelativistic formulas are derived for the NEET probability. The estimations show the probability to be less than the experimental data of [1] by one order of magnitude. The intermediate level is found to decay bypassing the isomeric level 16+, if the nucleus attributes a triaxial shape in the state and, besides, there exists a level 13- shifted with respect to 15- by 400 keV. We have shown also that the NEET cross section as a function of the energy of x-ray photons , has to accept constant value above the L photoionization threshold in contrast to narrow peak observed by [1].