Cover Explanation:
For the first time, Lyman alpha light at a wavelength of 121.6 nm has been observed as a product of the 3He(n,tp) nuclear reaction occurring in a cell of 3He gas. The cover illustration schematically shows the charged
particle tracks produced by the proton and triton reaction products passing through 3He gas, with each point of
light representing a Lyman alpha photon emission. A rendering of the experimental apparatus and neutron beam
is also shown. See the article by Thompson et al. in this issue for more about these measurements. Cover arranged
by C. Carey.