One-neutron removal reactions on light neutron-rich nuclei

Abstract

A study of high energy (43--68 MeV/nucleon) one-neutron removal reactions on a range of neutron-rich psd-shell nuclei (Z = 5--9, A = 12--25) has been undertaken. The inclusive longitudinal and transverse momentum distributions for the core fragments, together with the cross sections have been measured for breakup on a carbon target. Momentum distributions for reactions on tantalum were also measured for a subset of nuclei. An extended version of the Glauber model incorporating second order noneikonal corrections to the JLM parametrisation of the optical potential has been used to describe the nuclear breakup, whilst the Coulomb dissociation is treated within first order perturbation theory. The projectile structure has been taken into account via shell model calculations employing the psd-interaction of Warburton and Brown. Both the longitudinal and transverse momentum distributions, together with the integrated cross sections were well reproduced by these calculations and spin-parity assignments are thus proposed for $^{15}$B, $^{17}$C, $^{19-21}$N, $^{21,23}$O, $^{23-25}$F. In addition to the large spectroscopic amplitudes for the $\nu2$s$_{1/2}$ intruder configuration in the N=9 isotones,$^{14}$B and $^{15}$C, significant $\nu2$s$_{1/2}^2$ admixtures appear to occur in the ground state of the neighbouring N=10 nuclei $^{15}$B and $^{16}$C. Similarly, crossing the N=14 subshell, the occupation of the $\nu2$s$_{1/2}$ orbital is observed for $^{23}$O, $^{24,25}$F. Analysis of the longitudinal and transverse momentum distributions reveals that both carry spectroscopic information, often of a complementary nature. The general utility of high energy nucleon removal reactions as a spectroscopic tool is also examined.Comment: 50 pages, 19 figures, submitted to Phys. Rev.

β-delayed neutron andγ-ray spectroscopy of17C utilizing spin-polarizedUeno1, Miyatake2, Yamamoto3 et al. 2013Phys. Rev. C28160View full textAdd to dashboardCite

“…It has been experimentally shown that none of the odd mass neutron-rich carbon isotopes, GS assignment was performed through the study of GS properties based on the direct reaction [3][4][5][6][7], β-delayed neutron spectroscopy of the β decay of 17 C [8], and magnetic moment of 17 C [9]. In the extremely neutron-rich nucleus 19 C with N = 13, the I π GS value again becomes 1/2 + ; this was confirmed and discussed in connection with the formation of a neutron halo [6,10,11].…”

“…(1) 88 (2) 67 (1) 295 (2) 352 (1) 511 (2) 596 (5) 609 (2) 696 (8) 770 (2) 936 (2) 1123 (3) 1242 (3) 1411 (5) 4782 ( …”

In-beam γ-ray spectroscopy of the neutron-rich nitrogen isotopesN19−22

“…From these, it is expected that the states arising from a coupling of the p 1/2 proton hole to the 2 + , 4 + states of the 20 O core are mostly excited [7]. The ground state spin of 19,21 N was determined to be 1/2 − and that of 20 N to be 2 − [8]. No experimental data are available for the excited states of nitrogen nuclei heavier than A = 19.…”

One- and two-neutron removal from the neutron-rich carbon isotopes

“…Fast one-and two-neutron removal reactions from the neutron-rich carbon isotopes have been studied experimentally by several authors [8][9][10][11][12][13][14][15] 19 C (lower part). The energy intervals for transitions applicable to the inclusive cross sections for the indirect two-neutron removal (one-neutron removal followed by neutron emission), σ −1n(e) , and direct two-neutron removal, σ −2n(d) , reaction mechanisms are shown.…”