Allowed Gamow–Teller excitations from the ground state of 14N

Abstract

Motivated by the proposed experiment 14 N (d, 2 He) 14 C, we study the final states which can be reached via the allowed Gamow-Teller mechanism. Much emphasis has been given in the past to the fact that the transition matrix element from the J π = 1 + T = 0 ground state of 14 N to the J π = 0 + T = 1 ground state of 14 C is very close to zero, despite the fact that all the quantum numbers are right for an allowed transition. We discuss this problem, but, in particular, focus on the excitations to final states with angular momenta 1 + and 2 + . We note that the summed strength to the J π = 2 + T = 1 states, 1 calculated with a wide variety of interactions, is significantly larger than that to the J π = 1 + T = 1 final states.

Recoil alignment in muon capture onN14

“…We identified this peak as a 6978 keV gammaray originating from thermal neutron capture on chlorine-35. This identification was based on both its energy correspondence and reasonable consistency with observed intensities of other stronger 35 Cl(n, γ) lines. The 35 Cl(n, γ) background was believed to originate from polyvinyl chloride tape in the vicinity of the target.…”

Impact of off-diagonal cross-shell interaction on 14 C

“…Some results obtained from NCSM [28] and AMD [33] are compared with those from the shell model in Fig. 1.…”

“…The inclusion of the 4 ω in the present investigation is reasonable because of the existence of the states dominated by 2 ω configuration. [52], [33], and [28], respectively.…”

“…The long lifetime of 14 C is a long standing problem for theoretical models, which can be understood by the cancellation of the transition matrix elements between two main components in the p shell [1]. A few microscopic approaches based on N N (and N N N ) force are performed to investigate the origin of the extreme small B(GT) value between the ground states of 14 N and 14 C [28][29][30][31][32]. It should be noted that the energies of the first few positive states of 14 C and the B(GT) values for these states can not be well described in the above microscopic investigations, the antisymmetrized molecular dynamics (AMD) method [33], or the shell model in the 0−2 ω model space with existing Hamiltonians, such as WBP, SFO, and YSOX [27].…”

Computational nuclear quantum many-body problem: The UNEDF project

“…It is anomalously long compared with lifetimes of other light nuclei undergoing the same decay process, allowed Gamow-Teller (GT) beta decay. This lifetime poses a major challenge to theory because traditional realistic nucleon-nucleon (NN) interactions alone appear insufficient to produce the effect [14]. Since the transition operator, in leading approximation, depends on the nucleon spin and charge but not the spatial coordinates, this decay provides a precision tool to inspect selected features of the initial and final nuclear states.…”