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In ref. [1] a laser plasma with an electron temperature Θe ~ 1 keV, a lifetime of about 0.3 ns and a mass of ~ 1 μg was obtained from metallic rhenium containing isomeric nuclei of the 186mRe (T1/2, m = 2∙105 y). In such a plasma, there was observed stimulated de-excitation of isomeric 186mRe nuclei with a probability Pstim ~ 10 – 7, which was determined after a laser shot by the degree of disequilibrium between the decay of the isomers and the 186Re nuclei in the ground state (T1/2, g = 91 h).
The probability Pstim is proportional to the plasma lifetime, and to enhance the effect, it was proposed in ref. [2] to use instead of laser plasma an electric discharge plasma with the 186mRe isomeric nuclei, the lifetime of which increases up to ~ 10 ns while maintaining the temperature Θe ~ 1 keV. Such a plasma can be obtained in high-current Z-pinches at the Angara-5-1 facility at the JSC TRINITY. The plasma is formed during the implosion of a two-cascade cylindrical multi-wire assembly (liner) when a current pulse of ~ 4 MA passes through it, with a voltage of 1 MV and a duration of ~ 100 ns [3]. The outer cascade with a diameter of 12 mm with mass of ~ 300 μg/cm per unit liner length is composed of aluminum wires, the inner cascade with a diameter of 6 mm and a linear mass of ~ 20 μg/cm is composed of tungsten wires with a diameter of 6 μm. The material of the pinch plasma is mainly deposited at the ends of the discharge gap 16 mm long, from where a sample can be taken to determine the probability Pstim according to the method of ref. [1]. For the experiments, a technique was developed for introducing the 186mRe isomer into the liner by electrodeposition of a rhenium layer about 0.5 μm thick onto tungsten wires. The mass of rhenium in the liner will be ~ 10 μg. Thus, in the plasma of the Angara-5-1 facility, the amount of the 186mRe isomer can be an order of magnitude higher than in the laser plasma of the experiment [1], and the probability Pstim can be two orders of magnitude higher. All this shows that the proposed experiments at Angara-5-1 facility are promising.
References:
1. V.V. Vatulin, N.V. Zhidkov, A.A. Rimskii-Korsakov, V.V. Karasev, V.V. Koltsov, A.I. Kostylev, G.V. Tachaev, Bull. Russ. Acad. Sci.: Phys. 81, 1159 (2017).
2. V.V. Koltsov. “On stimulation of nuclear isomer de-excitation in plasma of electric explosion of conductors”. Proc. Int. Conf. “Nucleus-2018” - 68th Meeting on Nuclear Spectroscopy and Atomic Nucleus Structure. Voronezh, Russia. July 2-5, 127 (2018).
3. G.S. Volkov, V.I. Zaitsev, E.V. Grabovski, M.V. Fedulov, V.V. Aleksandrov, N.I. Lakhtyushko // Plasma Phys. Rep. 36, 191 (2010).
