Low energy proton irradiation on MgB2 bulk

This paper studies the effects of defects induced by 6 MeV protons on high-density pellets of MgB2. This methodology is useful to test the possibility to hinder the in-field decay of critical current density through extrinsic pinning centers as well as to check the radiation hardness of this material. Magnetic properties of two twin samples, the first one as-grown, the second one irradiated at a fluence of 0.8×1016 p/cm2 were measured and compared. The main outcome of the study is that this high-density material is quite hard with respect to irradiation with medium-energy proton beams. This makes MgB2 a good candidate for out-space applications. However some little modulation, either damage or enhancement, of the magnetic properties is observed. The impact of the effect is not sufficient to prevent the in-field decay of the magnetization, although it presents some interesting characteristics worth to be discussed in a framework of comparison with analogous results on HTSC. In particular, the results suggest some correlation between defects along the beam path. The main open issue concerns the existence of “hidden weak links”, hinted by the field dependence of the high-temperature persisting damage.