Pavol Mikula al. Nuclear Physics Institute, Řež. Czech Republic

Transcription

1 Pavol Mikula al. Nuclear Physics Institute, 2 68 Řež Czech Republic Kuala Lumpur, July 2-4, 29, 2nd RCM of the IAEA F1-RC on Improved production and utilization of short pulsed, cold neutrons at low-medium energy spallation neutron sources

2 Our main task within the contract : Development and optimization of a curved widewavelength band monochromator based on strongly cylindrically bent perfect Si-slabs in a sandwich for microfocusing small-angle neutron scattering (mfsans) device The main research task on the side of NPI Řež was preparation of crystal slabs for a sandwich type monochromator for a newly designed compact SANS instrument as proposed by Hokkaido University (prof. M. Furusaka) which would permit us to demonstrate a new type of inexpensive instrument which can be designed and realized for operation at different neutron wavelengths. Our laboratory has to provide know-how in the design and optimization performance of the required wide wavelength band focusing monochromators. Furthermore, our laboratory has to provide Siperfect crystals of a special cut for cylindrical bending.

3 Neutron production Reactor LVR 15, NRI Řež, CZ reactor power 1 MW thermal flux in the core ns -1 m -2 beam tube ns -1 m -2 fuel enrichment 36% 235 U tank type light water moderated and cooled

4 Experimental facilities installed at the reactor LVR-15 in Řež NBCT strain scanner II SANS multipurpose diffractometer powder diffractometer NDP powder diffractometer strain scanner I Radiative capture 1 2 m

5 Neutronový difractometr SPN Sample Monochromator drum Detector unit

6 What we have done? For Hokkaido University Two sets (2x3) of the perfect silicon crystal slabs of a special cut with the lattice planes (111) at the angle 67.5 deg have been prepared. The dimensions of the slabs are: 12x2x.5 mm 3 (length x width x thickness). Therefore, such a cut of the crystal slabs permits us to use the bent focusing monochromator in the so called fully asymmetric diffraction geometry when employing it just at the Bragg angle of 67.5 deg. Two sets (1x3 and 1x4) of the crystal slabs of the same orientation which will be used for mechanical tests (minimum curvature, optimum number of slabs in the sandwich) have been prepared. For HMI Berlin Two horizontally and vertically focusing monochromators and three sets of Si crystals with the main face parallel to 311, 331 and 4 lattice planes. For KAERI Daejeon One horizontally focusing monochromators and 17 Si crystal slabs of different cut. For JINR Dubna One horizontally focusing monochromators and Si(22) and Si(111) crystal slabs.

7 Collaborative works Horizontally and vertically focusing monochromator manufactured for HMI. 2 pieces, with Si(311) and Si(4) planes, figure of merit increased 1x. Horizontally focusing monochromator manufactured for KAERI different thicknesses of the Si(111) crystals and different asymmetric geometries.

8 Monte Carlo simulations KAERI Daejeon CIAE Beijing NECSA, South Africa JINR Dubna Kurchatov Inst. Moscow

9 Future plans and collaboration We are developing a long term collaboration with KAERI Daejeon. Within 29/1 we have to prepare two new horizontally focusing monochromators including Si(111) slabs of different thicknesses Construction of the horizontally and vertically focusing mono-chromator for CIAE Beijing for China Advanced Research Reactor Construction of the horizontally and vertically focusing monochromator for Mirrotron Budapest manufacturing whole stress diffractometer for Mianyang institute in Sichuan Construction of the horizontally focusing monochromator for BARC Mumbai (bending device ready, crystals in preparation) Construction of the horizontally focusing monochromator for Malaysian Nuclear Agency Monte Carlo simulations for KAERI Daejeon After clarifying some problems related to the lower efficiency of the present monochromator, new sets of crystals will be prepared for HU.

10 SANS instrumentation Double-crystal system slit geometry Double-bent-crystal high-resolution SANS camera Ultra high-resolution Bonse-Hart SANS camera

11 At home Reconstruction of the high resolution small-angle neutron scattering double crystal diffractometer: New collimator with the saphire filter New monochromator shielding Improved shielding between individual instruments Improved sample environment Reconstruction of the multipurpose neutron diffractometer: New detector arm (Huber) PSD detector New monochromator shielding Improved shielding between individual instruments

12 SANS Instrumentation SANS technique Collimator instruments size range 1 nm.. nm DC diffractometers with bent crystals 1 nm.. 1 µm DC diffractometers with perfect crystals (Bonse-Hart) 1 µm.. 1 µm Developed experimental technique Advanced data evaluation method & software multiple scattering Non-linear data fitting of a single model to multiple data sets

13 Double-Crystal SANS Diffractometer DN-2 beam tube with collimator beam shutter bent Si 22 bent Si 111 Instrument Parameters Monochromator bent perfect crystal Si 111 symmetric geometry Sample maximum 5x25 mm 2 Analyzer bent perfect crystal Si 111 fully asymmetric geometry bent Si 111 analyzer (asymmetric cut) samples Pb PE + B x = ( R sin(2 θ ) + L ) θ D A D S steel rods L D x D Detector 1-dimensional 3 He PSD resolution ~ 1 mm Wavelength λ = 2.1 A, λ/λ <.1 Neutron flux Q-resolution n s -1 cm -2 / R M = 3 m n s -1 cm -2 / R M = 35 m A -1 / R M = 3 m A -1 / R M = 35 m Vertical Q-resolution 1-1 A -1 Total Q-range A -1 position sensitive detector θ S diffraction planes 111

14 SANS-Diffractometer in NPI

15 Small-angle neutron scattering Study of porosity in plasma-sprayed ceramics SANS data for various resolutions and sample thickness fitted to a single model. Size distribution of pores in plasma-sprayed Al 2 O 3 z dσ/dθ z=2.5 mm z=5 mm empty beam 1 1 Q x [ µm -1 ] Bonse-Hart T=173 o C D(R) [1-2 µm -1 ] Collimator instruments as sprayed 13 o 15 C 152 o C 173 o C R [µm] 1 5

16 The most recent results Experimental powder diffraction test at a small take-off angle

17 Experimental test PSD detector Bent perfect crystal monochromator α-fe sample 2 mm diameter 4 mm width Monochromator take-off angle 3 o. No collimators were used.

18 Diffraction geometries Ψ= 22 o, t=4mm Ψ = 29.5 o, t=3 mm Ψ = o, t=4mm Ψ = o, t=4 mm Ψ = o, t=3x1.3 mm Ψ = o, t=1.3 mm PSD detector BPC-monochromator 2θ=3 deg Ψ Asymmetric transmission geometry, OBC BPC-monochrom ator Ψ= deg 2θ=3 deg PSD detector Spatial resolution of the PSD 2 mm 1 channel =.9 o Symmetric reflection geometry

19 Si 111, chi=29.5, 1/Ropt = Intensity [n/s] Si 111, chi=22, 1/Ropt =.26 Ge 111, chi=29.5, 1/Ropt =.31 Si 111, chi=35.26, 1/Ropt = MC simulations (output beam expansiom) Intensity [n/s] Si 111, chi= /Ropt =.4 Si 111, chi= /Ropt =-.25 Si 111, chi=, 1/Ropt =

20 2 1 MC simulations (output beam compression) Si 111, chi=-29.5, 1/Ropt = Intensity [n/s] Si 111, chi=-22, 1/Ropt =-.5 Ge 111, chi=-29.5, 1/Ropt =-.11 Si 111, chi=-35.26, 1/Ropt = Intensity [n/s] Si 111, chi= /Ropt =-.24 Si 111, chi=, 1/Ropt =.11

21 Experimental results: Asymmetric transmission geometry (OBC) FWHM / channel numbers si(111) Ψ=35.26 deg Output beam compression 2x4x4 mmm FWHM Peak height Peak height FWHM / channel numbers si(111) Ψ=22 deg Output beam compression 2*3*4 FWHM Peak height Peak height Bending /µm Bending / µm FWHM / channel numbers Ψ =29.5 deg 6 FWHM Output beam compression Peak height 2x3x3 mm Peak height Bending / µm 6

22 Experimental results: Symmetric reflection geometry FWHM / channel numbers Si(111) Symmetric reflection 2x4x4 mm FWHM Peak height Bending / µm Peak height FWHM / channel numbers Si(111) sandwich Symmetric reflection 2*4*3x1.3 mm FWHM Peak height Bending / µm Peak height FWHM / channel numbers Si(111) 8 Symmetric reflection FWHM 2*4*1.3 mm Peak height Peak height Bending / µm

23 Diffraction peaks of α-fe(211) for different measurement times 4 Exp. points Gauss fit y ± xc ± w ± A ± Exp. points Gauss fit y ± xc ±.2455 w ± A ± Intensity / 18 s 3 2 Intensity / 6 s Intensity / 2 s Exp. points Gauss fit Channel number y ± xc ±.2819 w ±.5927 A ± Channel number 18 s α-fe-pin, Φ=2 mm 6 s Intensity / 5 s Exp. points Gauss fit y ±.9552 xc ± w ± A ± Channel number 2 s 5 s Channel number

24 Related publications 1. P. Mikula, M. Vrána, V. Wagner, M. Furusaka, Nucl. Instrum. Methods in Phys. Research, Section A, A586 (28) P. Mikula, M. Vrána, and V. Wagner, Chapter in the book Modern Developments in X-ray and Neutron Optics, eds. A. Erko, M. Idir, T. Krist, A.G. Michette, Springer Berlin/Heidelberg, Volume 137/28, pp R.C. Wimpory, P. Mikula, J. Šaroun, T. Poeste, Junghong Li, M. Hoffmann and R. Schneider, Efficiency Boost of the Materials Science Diffractometer E3 at BENSC: One Order of Magnitude, Due to a Double Focusing Monochromator, Neutron News, 19 (28) R.C. Wimpory, P. Mikula, J. Šaroun, T. Poeste, R. Schneider, J. Li and M. Hoffmann, Efficiency Boost of the Materials Science Diffractometer E3 at BENSC: One Order of Magnitude, BENSC Experimental Report 27, HMI Berlin, Edited by U. Stahnke, A. Brandt and H.A. Graf, April 28, HMI-B 617, ISSN M. Furusaka, K. Kamada, Y. Kiyanagi, F. Fumiyuki, A. Homma, K. Ikeda, K. Hirota, H. Shimizu, S. Satoh, P. Mikula, T. Satoh, K. Tanabe, K. Koyama, H. Takahashi, K. Fujita, T. Kamiyama, S. Naito, Y. Kawamura, H. Yoshizawa, S. Ikeda, First results from a mini-focusing Small-Angle Neutron Scattering Instrument (mfsans) with an ellipsoidal mirror, In Proc. of the Int. Conf. On Advanced Neutron Sources ICANS XVIII, April 26-29,27, Dongguan, China. 6. M. Furusaka, T. Satoh, Y. Sasaki, Y. Kawamura, T. Asami, Y. Otake, K. Ikeda, P. Mikula, Y. Kiyanagi, S. Naito, H. Yoshizawa, Installation of a prototype of focusing-type small-angle neutron scattering instrument with an ellipsoidal supermirror, Activity Report on Neutron Scattering Research: Experimental Reports 15 (28), Report Number: 655, Tokyo University