Polycapillary focusing optic for small-sample neutron crystallography

The relatively low flux from neutron sources means that structural analysis using neutron diffraction requires large crystals that are often not available. The feasibility of a polycapillary focusing optic to produce a small intense spot of size < ∼0.5 mm for small crystals has been explored and such an optic has been tested both on a monochromatic and on a polychromatic beam. In a diffraction measurement from an α-quartz crystal using a 2.1° convergent beam from a pulsed neutron source, six diffraction peaks in the 1.5–4 Å wavelength bandwidth transmitted by the optic were observed. These diffraction spots show an intensity gain of 5.8 ± 0.9 compared with a direct beam diffracting from the same sample volume as that illuminated by the convergent beam.

THE LASER IGNITION DEVICE AND ITS APPLICATION TO OIL SPILLS

ABSTRACT A laser ignition device, intended initially for the controlled burning of forest logging slash, has been developed and successfully tested, for this and other applications. The device employs a kilowatt class carbon dioxide laser, the output of which is beam expanded and then focused to give a small, intense spot of heat at distances from approximately 50 to 1,500 m. Acquisition and precise focus control are achieved by the use of a laser rangefinder and acquisition telescope. The device is fully steerable, can be ground based, airborne, or mounted on seacraft.