Detection efficiency of a neutron monitor calibrated by an accelerator neutron beam

Abstract The neutron monitor developed by Simpson (Phys. Rev. 73 (1948) 1389) has been widely used to measure the intensity of cosmic rays. However, the detection efficiency of the neutron monitor has never been calibrated using an accelerator beam. This paper gives the first results of measurements of the detection efficiency of the neutron monitor using the accelerator beam at RCNP, Osaka University. The experimental data reproduce both the early prediction by Hatton and the recent calculation by Clem surprisingly well.