Electron capture beta decay of partially polarized nuclei

In this paper, we compute the spin excess for the neutrinos radiated in the process of electron capture beta decay of partially polarized nuclei. The results of computation are presented for the [Formula: see text] nuclei polarized by the strong hyperfine field in a ferromagnetic substance. This system was suggested as a possible source of monoenergetic neutrino radiation with a preferable direction of neutrino propagation. We directly compute the spin excess of radiated neutrinos and show that it is slightly greater than that estimated previously under simplifying assumptions.

Magnetic hyperfine field splitting in the Zintl phase Eu2Mg4Si3

Eu2Mg4Si3 ≡ (2Eu2+)(4Mg2+)(3Si4−) is an electron-precise Zintl phase. Its Hf2Co4P3-type structure contains three crystallographically independent europium sites. The divalent state of europium was manifested through 151Eu Mössbauer spectroscopy. In the paramagnetic regime (T = 78 K) the isomer shifts range from −9.16 to −11.29 mm s−1. Eu2Mg4Si3 shows complex magnetic hyperfine field splitting at T = 5.7 K with a superposition of three subspectra with magnetic hyperfine fields of 5.4 (Eu2), 20.4 (Eu1) and 22.4 (Eu3) T.