Abstract
We have studied the effects of fast neutron (E>0.1 MeV) irradiation at reactor (∼ 360 K) and low (∼ 20 K) temperatures on the superconducting properties of polycrystalline orthorhombic YBa2Cu3O7−y . Measurements were made on the superconducting critical temperature Tc , critical current Jc , Meissner effect and magnetic field dependence of Jc . The Tc drops by an irradiation at reactor temperature and Jc increases with increasing fluence. On the other hand with the irradiation at low temperature, Tc rises and Jc increases. Results of observation of Meissner effect and the magnetic field dependence of Jc are consistent with the behavior of Tc and Jc .