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Recently, in a laser plasma with an average electron temperature
Θ ~ 1 keV and a lifetime τ ≈ 0.3 ns, it was found out the stimulation of de-excitation of nuclear isomers (SDENI) Re-186m (half-life T = 2×10E5 years) to the ground state of the Re-186 nuclei (T = 90 hours) with a probability P ≈ 1·10E(–7), which apparently occurred through an intermediate trigger level with a half-life of ~ 10 days. To increase the SDENI probability, it was proposed to use longer-lived electric discharge plasma instead of laser plasma (see Ref. [1] and references in there).
In Ref. [2], a methodology for SDENI experiments was developed for Re-186m isomers in the Z-pinch plasma of the “Angara-5-1” facility at Troitsk Institute for Innovation and Fusion Research. Plasma was obtained by implosion of a two-cascade cylindrical multiwire assembly (liner) with a current pulse of 4 MA and 1 MV voltage passing through it. The outer cascade of the liner with a diameter of 12 mm and a linear mass of 300 μg/cm was composed of Al-wires with a diameter of 8 μm, and the internal cascade with a diameter of 6 mm and a linear mass of
20 μg/cm was made of W-wires of 6 μm diameter. A Re-layer of 0.5 μm thick with the Re-186m isomer was deposited on W wires by electrolysis. The first experiments showed a SDENI-induced disturbance of the radioactive equilibrium between the isomer and the ground state of the Re-186 nucleus in Z-pinch plasma at Θ = 400 eV and τ = 10 ns. The intensity I of 137 keV γ-quanta of Re-186 decay from a sample of plasma matter after three plasma shots, decreased with time t and reached its stationary value after t ≈ 40 days. Based on the parameters of the I(t) time dependence, we estimated the SDENI probability of P ≈ 2·10 – 7 in the plasma.
The work was supported by the Private Enterprise “Science and Innovations” (ROSATOM) (contract No. 774/569-D).
- V. Koltsov // “On the stimulation of the de-excitation of nuclear isomers in plasma of a high-current electric discharge”. Plasma Phys. and Techn. 2021. V. 8(1). P. 5.
- G.S. Volkov, E.V. Grabovski, A.N. Gritsuk, V.V. Karasev, V.V. Koltsov // “On the possibility of observing stimulated de-excitation of nuclear isomer Re-186m in a high-current Z-pinch plasma at the Angara-5-1 setup”. Phys. At. Nucl. 2022. V. 85(9). P. 1486.
| Section | Experimental and theoretical studies of nuclear reactions |
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