Magnetic moments ofN17andB

Abstract

The magnetic moments of 17 N and 17 B were measured by using spin-polarized radioactive nuclear beams which were obtained from the projectile fragmentation reaction. The observed magnetic moment of 17 N, ͉͑ 17 N͉͒ϭ͑0.352Ϯ0.002͒ N , where N is the nuclear magneton, falls outside the Schmidt lines. By virtue of a simplifying feature of nuclear structure inherent in a p 1/2 valence nucleus, the deviation from the Schmidt value is attributed on firm ground to admixing of the configurations in which two neutrons in the sd shell are coupled to J ϭ2 ϩ. This interpretation is confirmed in standard shell-model calculations. The calculations reproduce fairly well the experimentally inferred amount of 2 ϩ admixture, as well as the experimental magnetic moment itself. The magnetic moment for 17 B was determined as ͉͑ 17 B͉͒ϭ͑2.545Ϯ0.020͒ N. The result is substantially smaller than the p 1/2 single-particle value, and the shell-model calculations indicate that the quenching of largely stems from J ϭ2 ϩ configurations of the sd neutrons. The observed amount of quenching, however, is larger than the shell-model predictions, suggesting an enhanced contribution of the 2 ϩ neutron configurations. This result is explained if the pairing energy for neutrons in the sd shell of a neutron-rich nucleus is assumed to diminish by about 30%. We also find that the use of the reduced pairing energy improves agreements in the magnetic moment and low-lying energy levels of 17 N as well. ͓S0556-2813͑96͒05005-4͔

Possibility to study a two-proton halo inNe17

“…To derive it from experimental data it is necessary to know the sensitivity of various observables to this aspect of the dynamics. We show that currently available experimental data are insufficient to determine reliably the structure (and possible halo properties) of 17 Ne. We can, however, confidently define which kind of experimental data is required to resolve the puzzling issues of the 17 Ne structure.…”

“…We estimated the matter radius of 15 CDE. -This is the only observable, for which a sensitivity to 17 Ne structure far exceeds an experimental uncertainty. Calculations [2] provide the WF with about 50 % s/d mixing (GMZ case) reproducing experimental [5], we get a good agreement with these calculations for GMZ WF.…”

“…However, in paper [14] the β-decay asymmetry was successfully explained in these terms. It seems that theoretical agreement about the basic properties of 17 Ne is still missing at the moment.…”

“…In papers [7,15] the comparatively narrow core momentum distribution was interpreted as possible evidence for proton halo in 17 Ne. This is a reasonable approach to the problem, as among typical experimental evidences for halo (e.g.…”

β-delayed neutron andγ-ray spectroscopy of17C utilizing spin-polarizedUeno1, Miyatake2, Yamamoto3 et al. 2013Phys. Rev. CSelf Cite28160View full textAdd to dashboardCite

“…Instead, as soon as a 17 B particle was identified by the beam-line counters equipped with RIPS, the beam bombardment was turned off for 19.5 ms. At the beginning of the beamoff period, the B 1 field ≃ 1.6 mT was applied for a duration of T R = 1.5 ms, and in this duration, the frequency of B 1 was swept over the Larmor frequency ν 0 of 17 B [31] in the frequency window ∆ν/ν 0 = 2%. Then, the β rays, in addition to γ rays and neutrons, were measured during a subsequent time period of T C = 18 ms. After the beam-off period, the beam bombardment was again turned on until the next 17 B particle was detected.…”