A COLD/THERMAL BEAM BENDER USING CAPILLARY OPTICS TO INCREASE THE NUMBER OF END-GUIDE INSTRUMENT POSITIONS

THE DEVELOPMENT AND USE OF NONDESTRUCTIVE, NEUTRON-BASED ANALYTICAL TECHNIQUES FOR MATERIALS CHARACTERIZATION-INCLUDING NEUTRON-SCATTERING APPLICATIONS USING COLD AND THERMAL NEUTRONS-HAVE BEEN HINDERED BY LIMITED ACCESS TO HIGH FLUX SOURCES OF LOW ENERGY NEUTRONS. THIS PROJECT IS DEVELOPING A DEVICE THAT WOULD TRANSMIT A WIDE WAVELENGTH RANGE OF COLD AND THERMAL NEUTRONS THROUGH A SMALL RADIUS OF CURVATURE, ENABLING THE CREATION OF SEVERAL END POSITIONS ON A SINGLE NEUTRON GUIDE. THE RESULTING BEAMS WOULD BE ESSENTIALLY FREE OF CONTAMINATION FROM EPITHERMAL NEUTRONS AND GAMMA-RAYS. THE NEUTRON BEAM BENDER WOULD CONSIST OF ANY ARRAY OF CAPILLARIES WITH SMALL DIAMETER CHANNELS THROUGH WHICH THE NEUTRONS WOULD MAKE MULTIPLE REFLECTIONS AT ANGLES LESS THAN THE CRITICAL ANGLE OF REFLECTION. SUCH CAPILLARY-BASED DEVICES, REFERRED TO AS KUMAKHOV OPTICS, HAVE DEMONSTRATED THE CAPABILITY TO REDIRECT X-RAYS. PRELIMINARY DATA INDICATE HIGH TRANSMISSION EFFICIENCY FOR NEUTRONS DEFLECTED THROUGH A SMALL RADIUS OF CURVATURE. PHASE I STUDIES ARE EVALUATING THE FEASIBILITY OF DEVELOPING A COMPLETE DEVICE BY ANALYZING THE RESULTS OF MEASUREMENTS AND BY USING MONTE CARLO SIMULATIONS OF TRANSMISSION EFFICIENCY THROUGH CURVED CAPILLARIES FOR A WIDE WAVELENGTH RANGE. ANALYSIS OF THESE RESULTS WILL ENABLE DESIGN AND TESTING OF A PROTOTYPE NEUTRON BEAM BENDER DURING PHASE II.