2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/83145The hyperfine effect in muon capture rate is analyzed with taking into account of the second-order terms in 1/M in the non-relativistic Hamiltonian. It is shown that in the situation of the dominance of the squared first-order terms the interference of zero-order and second-order terms has no significant influence. General expression for neutrino (recoil nucleus) angular distribution in muon capture by nucleus with non-zero spin is proposed. High sensitivity to $g_P$ of the term related with alignment of the initial mesic atom is discussed in the approximation of dominating Gamow--Teller matrix element.12 pages, latex, no figures, report at INPC98 (Paris)Nuclear TheoryHigh Energy Physics - Phenomenologytext