Magnetic moment of proton halo nucleus 28P

The magnetic moment of 28p (Iπ =3+, T1/2 =270.3 ms) in the ground state has been measured by the β-nuclear magnetic resonance method for the first time. The measured magnetic moment of |μ(28P)|=0.309(9) μN is well reproduced by the shell model value of +0.306 μN. The shell model calculation also yields a proton density distribution with a long tail. The present results provide a strong confirmation of the configuration of the 2s1/2 proton which should lead to the proton halo.