The spectral dependence of the transmission of a collimated neutron be
am by disordered quartz microstructures is measured. The observed mean
free paths are very short, down to 200 nm. The results show that scat
tering with a characteristic value of the parameter kl less than or eq
ual to 10 is realized near the neutron total external reflection edge.
(C) 1998 American Institute of Physics. [S0021-3640(98)00105-4].