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Full text (en) Triggering of 178Hfm2 by photoinduced electron transition
A. Ya. Dzyublik1
1Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, Ukraine
Abstract: 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 16+ isomer is assumed to be excited into an intermediate state 15- 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 15- 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 σNEET(E) as a function of the energy of x-ray photons E, has to accept constant value above the L3 photoionization threshold in contrast to narrow peak observed by [1].
Keywords: nuclear isomers, NEET, induced nuclear decay, x-rays, hafnium, nuclear spectra.
References:1. Collins C. B., Zoita N. C., Davanloo F. et al. Accelerated γ-emission from isomeric nuclei. Radiat. Phys. Chem. 71 (2004) 619. https://doi.org/10.1016/j.radphyschem.2004.04.033
2. Collins C. B., Davanloo F., Iosif M. C. et al. Accelerated emission of gamma rays from the 31-yr isomer of 178Hf induced by x-ray irradiation. Phys. Rev. Lett. 82 (1999) 695. https://doi.org/10.1103/physrevlett.84.2542
3. Collins C. B., Davanloo F., Iosif M. C. et al. Evidence for the forced gamma emission from the 31-year isomer of Hafnium-178. Laser Phys. 9 (1999) 1.
4. Collins C. B., Davanloo F., Rusu A. C. et al. γ emission from the 31-yr isomer of 178Hf induced by x-ray irradiation. Phys. Rev. C 61 (2000) 054305(7). https://doi.org/10.1103/PhysRevC.61.054305
5. Collins C. B., Davanloo F., Zoita N. C. et al. Gamma-Ray Transitions Induced in Nuclear Spin Isomers by X-Rays. Hyperf. Interact. 135 (2001) 51. https://doi.org/10.1023/A:1013959015577
6. Collins C. B., Zoita N. C., Rusu A. C. et al. Tunable synchrotron radiation used to induce γ-emission from the 31 year isomer of 178Hf. Erophys. Lett. 57 (2002) 677. https://doi.org/10.1209/epl/i2002-00516-1
7. Tkalya E. V. Induced decay of nuclear isomer 178m2Hf and "isomer bomb". Usp. Fiz. Nauk 175 (2005) 555.
8. Ahmad I., Dunford R. W., Gemmell D. S. et al. Search for x-ray induced decay of the 31-yr isomer of 178Hf using synchrotron radiation. Phys. Rev. C 71 (2005) 024311(16). https://doi.org/10.1103/PhysRevC.71.024311
9. Carroll J. J., Karamian S. A., Propri R. et al. Search for low-energy induced depletion of 178Hfm2 at the SPring-8 synchrotron. Phys. Lett. B 679 (2009) 203. https://doi.org/10.1016/j.physletb.2009.07.025
10. Ho Yu-kun, Yuan Zhu-shu, Zhang Bao-hui, Pan Zheng-ying. Self-consistent description for x-ray, Auger electron, and nuclear excitation by electron transition processes. Phys. Rev. C 48 (1993) 2277. https://doi.org/10.1103/PhysRevC.48.2277
11. Tkalya E. V. Nuclear excitation in atomic transistions (NEET process analysis). Nucl. Phys. A 539 (1992) 209. https://doi.org/10.1016/0375-9474(92)90267-N
12. Harston M. R. Analysis of probabilities for nuclear excitation by near-resonant electronic transitions. Nucl. Phys. A 690 (2001) 447. https://doi.org/10.1016/S0375-9474(01)00358-X
13. Tkalya E. V. Theory of the nuclear excitation by electron transition process near the K edge. Phys. Rev. A 75 (2007) 022509(6). https://doi.org/10.1103/PhysRevA.75.022509
14. Dzyublik A. Ya. Photo-induced nuclear excitation by electron transition. JETP Letters 93 (2011) 489. https://doi.org/10.1134/S0021364011090050
15. Kishimoto S., Yoda Y., Kobayashi Y. et al. Nuclear excitation by electron transition on 197Au by photoionization around the K-absorption edge. Phys. Rev. C 74 (2006) 031301(4). https://doi.org/10.1103/PhysRevC.74.031301
16. Tkalya E. V. Probability of L-shell nuclear excitation by electron transition in 178Hfm2. Phys. Rev. C 68 (2003) 064611. https://doi.org/10.1103/PhysRevC.68.064611
17. Harston M. R., Carroll J. J. Limits on nuclear excitation and deexcitation of 178Hfm2 by electron-nucleus coupling. Laser Phys. 15 (2005) 487.
18. Bethe H. A., Salpeter E. K. Quantum Mechanics of One- and Two-electron Atoms (N.-Y.: Academic Press Inc., 1957) 369 p.
19. Davydov A. S. Excited States of Atomic Nuclei (Moscow: Atomizdat, 1967) 263 p.
20. Frish S. Optical Spectra of Atoms (Moscow: Fiz.- Mat. Lit., 1963) 641 p.
21. Bohr A., Mottelson B. Nuclear Structure. Vol. 1 (N.-Y. - Amsterdam: W. A. Benjamin, Inc., 1969) 471 p.
22. Campbell J. L., Papp T. Widths of the atomic K-N7 levels. At. Data and Nucl. Data Tables 77 (2001) 1. https://doi.org/10.1006/adnd.2000.0848
23. Preston M. A. Physics of the Nucleus (Massachusetts: Addison-Wesley, 1962; Moscow, 1964) 574 p.
24. Bearden J. A., Burr A. F. Reevaluation of X-Ray Atomic Energy Levels. Rev. Mod. Phys. 39 (1967) 125. https://doi.org/10.1103/RevModPhys.39.125