کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10715792 | 1027369 | 2011 | 5 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The plain truth about forming a plane wave of neutrons
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موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
ابزار دقیق
پیش نمایش صفحه اول مقاله
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چکیده انگلیسی
We have attained the first sub-arcsecond collimation of a monochromatic neutron beam by diffracting neutrons from a Bragg prism, viz. a single crystal prism operating in the vicinity of Bragg incidence. Analytical as well numerical computations based on the dynamical diffraction theory, led to the optimised collimator configuration of a silicon {1Â 1Â 1} Bragg prism for 5.26Â Ã
neutrons. We fabricated a Bragg prism to these specifications, tested and operated it at the double diffractometer setup in Helmholtz Zentrum Berlin to produce a 0.58Â arcsec wide monochromatic neutron beam. With a similarly optimised Bragg prism analyser of opposite asymmetry, we recorded a 0.62Â arcsec wide virgin rocking curve for this ultra-parallel beam. With this nearly plane-wave neutron beam, we have recorded the first ever USANS spectrum in Qâ¼10â6Â Ã
â1 range with a hydroxyapatite casein protein sample and demonstrated the instrument capability to characterise agglomerates up to 150 μm in size. The super-collimated monochromatic beam has also enabled us to record the first neutron diffraction pattern from a macroscopic grating of 200 μm period. The transverse coherence length of 175 μm (FWHM) of the ultra-parallel beam derived from the analysis of this pattern, is the greatest achieved to date for Ã
wavelength neutrons.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment - Volume 634, Issue 1, Supplement, 1 April 2011, Pages S41-S45
Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment - Volume 634, Issue 1, Supplement, 1 April 2011, Pages S41-S45
نویسندگان
Apoorva G. Wagh, Sohrab Abbas, Wolfgang Treimer,