RESUMO
This study investigates the phase shift induced by Laue transmission in a perfect Si crystal blade in unprecedented detail. This `Laue phase' was measured at two wavelengths in the vicinity of the Bragg condition within a neutron interferometer. In particular, the sensitivity of the Laue phase to the alignment of the monochromator and interferometer (rocking angle) and beam divergence has been verified. However, the influence of fundamental quantities, such as the neutron-electron scattering length, on the Laue phase is rather small. The fascinating steep phase slope of 5.5° [(220) Bragg peak] and 11.5° [(440) Bragg peak] per 0.001â arcsec deviation from the Bragg angle has been achieved. The results are analysed using an upgraded simulation tool.
RESUMO
The currently largest perfect-crystal neutron interferometer with six beam splitters and two interference loops offers novel applications in neutron interferometry. The two additional lamellas can be used for quantitative measurements of a phase shift due to crystal diffraction in the vicinity of a Bragg condition. The arising phase, referred to as "Laue phase," reveals an extreme angular sensitivity, which allows the detection of beam deflections of the order of 10(-6) s of arc. Furthermore, a precise measurement of the Laue phase at different reflections might constitute an interesting opportunity for the extraction of fundamental quantities like the neutron-electron scattering length, gravitational short-range interactions in the sub-micron range and the Debye Waller factor. For that purpose several harmonics can be utilized at the interferometer instrument ILL-S18.
RESUMO
The phenomenon of a neutron phase shift due to Laue transmission in a perfect crystal blade is discussed. Quantitative measurements of this phase shift are presented in the vicinity of the Bragg condition well in agreement with numerical calculations. The phase shift shows a strong angular sensitivity and might constitute an interesting opportunity for precision measurements of fundamental quantities like the neutron-electron scattering length or gravitational short-range interactions.
RESUMO
Boron alloyed stainless-steel sheets are predominantly used in nuclear engineering as neutron shielding for radioactive waste disposal equipment. The neutron absorption depends strongly on the amount and the distribution of the 10B isotope. A systematic transmission study of 10B enriched steel plates by means of neutron time-of-flight and neutron radiography experiments was performed. The 10B content was analyzed with accuracy up to 5 x 10(-3) wt% using monochromatic beams and a linear increase of the macroscopic cross section with the 10B content was found even for strong absorbers. Then we extended the transmission analysis to "white" thermal neutron beams where large deviations from the exponential transmission law are observed. The influence of the spectral width is discussed in more detail because beam hardening causes an elevation of the effective transmission through strong absorbing materials, an effect which is crucial for the design of neutron shielding.
