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G. F. Grinyer

Publications and source records attributed to G. F. Grinyer.

39 records · Page 3Linked to original sources
arXiv2009

Spectroscopy of 13B via the 13C(t,3He) reaction at 115 AMeV

Gamow-Teller and dipole transitions to final states in 13B were studied via the 13C(t,3He) reaction at Et = 115 AMeV. Besides the strong Gamow-Teller transition to the 13B ground state, a weaker Gamow-Teller transition to a state at 3.6 MeV was found. This state was assigned a spin-parity of 3/2- by comparison with shell-model calculations using the WBP and WBT interactions which were modified to allow for mixing between nhw and (n+2)hw configurations. This assignment agrees with a recent result from a lifetime measurement of excited states in 13B. The shell-model calculations also explained the relatively large spectroscopic strength measured for a low-lying 1/2+ state at 4.83 MeV in 13B. The cross sections for dipole transitions up to Ex(13B)= 20 MeV excited via the 13C(t,3He) reaction were also compared with the shell-model calculations. The theoretical cross sections exceeded the data by a factor of about 1.8, which might indicate that the dipole excitations are "quenched". Uncertainties in the reaction calculations complicate that interpretation.

nucl-ex↗
arXiv2009

Doubly-magic nature of 56Ni: measurement of the ground state nuclear magnetic dipole moment of 55Ni

The nuclear magnetic moment of the ground state of $^{55}$Ni ($I^π=3/2^{-}, T_{1/2}=204$ ms) has been deduced to be $|μ$^{55}Ni)$|=(0.976 \pm 0.026)$ $μ_N$ using the $β$-NMR technique. Results of a shell model calculation in the full \textit{fp} shell model space with the GXPF1 interaction reproduce the experimental value. Together with the known magnetic moment of the mirror partner $^{55}$Co, the isoscalar spin expectation value was extracted as $<\sum σ_z >=0.91 \pm 0.07$. The $<\sum σ_z>$ shows a similar trend as that established in the \textit{sd} shell. The present theoretical interpretations of both $μ(^{55}$Ni) and $<\sum σ_z>$ for the $T=1/2$, A=55 mirror partners support the softness of the $^{56}$Ni core.

nucl-ex↗