A NEUTRON BEAM CONCENTRATING OPTIC FOR NEUTRON RADIOGRAPHY NDE

THERMAL AND COLD NEUTRON RADIOGRAPHY NON-DESTRICTIVE EVALUATION (NDE) SHOULD HAVE MANY ADVANTAGES OVER X-RAY RADIOGRAPHY IN AEROSPACE APPLICATIONS. UNFORTUNATELY, THE GENERATION OF THERMAL NEUTRONS RESULTS IN LOW BEAM FLUX AND DIFFUSE SOURCES RESULTING IN LONG EXPOSURE TIMES AND POOR RESOLUTION. PHYSICON PROPOSES THE USE OF A NOVEL OPTIC TO COLLIMATE AND CONCENTRATE NEUTRON BEAMS WHICH WILL LOWER EXPOSURE TIMES AND PRODUCE BETTER RESOLUTION. THIS OPTIC IS BASED UPON GRAZING INCIDENCE REFLECTION FROM THE CHANNEL WALLS OF A BENT MICROCHANNEL PLATE. SUCH AN OPTIC WOULD HAVE A LARGE APERTURE AND SMALL LINEAR DIMENSION PERPENDICULAR TO THE APERTURE PLANE. WE EXPECT TO PRODUCE FLUENCE GAINS OF AT LEAST IO WITH THE PROTOTYPE CONSTRUCTED IN PHASE I AND HIGHER GAINS IN PHASE II. THE OPTIC WILL ALSO BE ABLE TO PRODUCE A BRIGHT NEAR POINT SOURCE OF COLD NEUTRONS WHICH WILL ALLOW VERY HIGH RESOLUTION IMAGING. WE WILL CONSTRUCT THE REFLECTOR FROM THIN ALUMINUM STRIPS COATED WITH A VERY THIN, VERY SMOOTH COAT OF NICKEL. THE STRIPS ARE WOUND ON A TAPERED MANDREL TO FORM A SPIRAL MICROCHANNEL WITH A VERY HIGH OPEN AREA RATIO AND VERY SMOOTH CHANNEL WALLS. OUR SPIRAL WILL THEN HAVE ITS END FACES SHAPED AND THE RESULTING DEVICE WILL ACT VERY MUCH LIKE A NEUTRON LENS. A CONCENTRATOR/COLLIMATOR OF THIS SORT WILL GREATLY ENHANCE THE CAPABILITIES OF NEUTRON RADIOGRAPHY AND MAKE MOBILE RADIOGRAPHY SOURCES PRACTICAL.