 The
first goals for making non conducting, non-magnetic neutron guides from
carbon have been reached. The use of pulsed laser deposition (PLD)
from a graphite target has eliminated the hydrogen inherent to chemical
vapor deposition (CVD) techniques. The PLD surfaces also exhibit
smoothness on the order of the substrate used. And the latest goal
to be achieved is a material potential greater than beryllium the best
non-magnetic UCN coating. A film's material potential determines
the highest energy neutron it can stop. The neutron velocity,
which yields a kinetic energy equal to the materials potential, is called
the critical velocity. Neutron reflectometry results have show our
PLD diamond-like carbon films to have a critical velocity greater than
seven meters per second and further work should increase this closer to
the diamond limit of 7.5 m/s. This is greater than all coatings except
58Ni. |