Ядерна фізика та енергетика Nuclear Physics and Atomic Energy   ISSN: 1818-331X (Print), 2074-0565 (Online)   Publisher: Institute for Nuclear Research of the National Academy of Sciences of Ukraine   Languages: Ukrainian, English   Periodicity: 4 times per year   Open access peer reviewed journal

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Yu. G. Shchepkin, N. I. Mazina^*, V. I. Slisenko

Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, Ukraine

^*Corresponding author. E-mail address: nadin_v@ukr.net

Abstract: The technique for investigating isomeric states of nuclei with a large values of energy and total momentum created in the neutron capture reaction has been developed. The technique is based on the spectrometry of multiplicity, energy, and time of registration of instantaneous and delayed gamma cascades of isomer occupancy and decay, respectively. The technique was tested in measurements of the isomeric ratio of the ¹⁸³W level with energy E_iz = 1.285 MeV with total moment J^π_iz = 4^-, 5^- and lifetime T_iz = 8.2 μs in the neutron absorption reaction, which is equal to α_iz = (4.7 ± 0.9)⋅10^-3. At large values of the efficiency of registration of acts of settlement and decay of the isomer (0.6 - 0.8), the level of the corresponding background of the spectrometer is only 3.5⋅10^-4 s^-1. At the countable load at the spectrometer input ∼1.5⋅10³ s^-1, the expected sensitivity of determining the isomeric ratio in measurements with the mono isotope of the sample is α_iz ∼(0.3 ± 1.0)⋅10^-4.

Keywords: isomer, compound state, gamma cascade, statistical model, spectrometry, energy, multiplicity, registration efficiency, coincidence rate.

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