Measured operational neutron energies of compound refractive lenses

The characteristics of two compound refractive lenses (CRLs) have been measured using a broadband spallation neutron source. One CRL consists of a stack of 98 biconcave, spherical lenses made of MgF2, and another consists of 198 biconcave, spherical lenses made of Al. The bandwidth of the spallation source included wavelengths from 1.5 Å to 15.7 Å that we could use to test the CRLs. The MgF2 CRL was found to be useful from 9 to 15 Å with the maximum transmission around 13 Å, whereas the Al CRL was found to give good transmission around 5-15 Å, with the maximum transmission around 8 Å. Spectra with Al lens and MgF2 CRLs show multiple transmission dips due to Bragg diffraction of the microcrystal structure of the lens materials (Al or MgF2). These measurements helped characterize the CRLs for possible applications at shorter wavelengths than previously used.