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I-2. Development and optimization of a curved wide wavelength band monochromator based on strongly cylindrically bent perfect Si-slabs in a sandwich for minifocusing small-angle neutron scattering (mfSANS) device Chief Scientific Investigator: RNDr. Pavol Mikula DrSc. Nuclear Physics Institute v.v.i., AS CR, 25068 Rez, Czech Republic Fax: +420-220940141, E-mail: mikula@ujf.cas.cz I-2.1. Short summary of work performed in the NPI during the last 3-4 years which is related to the contract Neutron diffraction group of Neutron Physics Department of NPI Řež has a high credit in neutron scattering community and keeps world priority in application of Bragg diffraction optics based on cylindrically bent perfect crystals in neutron diffractometry and spectrometry. In the last 4 years the activity has been followed in two ways: An employment of already developed focusing devices based on cylindrically bent perfect crystals in high resolution neutron diffractometers and spectrometers and testing of new designs of high and ultrahigh resolution focusing monochromators/analyzers [1-12]. First, in 2007 we have provided know-how and two focusing devices for double crystal SANS diffractometer for Demokritos Institute in Athens. Then, similarly we have provided two horizontally and vertically focusing devices to HMI Berlin, where after an installation the figure of merit of neutron diffractometer has increased by a factor of 12. Also in 2006 we have provided focusing monochromators to BARC Mumbai and in 2005 and in 2008 to KAERI Daejeon and JINR Dubna. However, NPI has been engaged to a large extent in Monte Carlo simulations of neutron scattering devices employing neutron optics elements. Such MC simulations have been done namely for HMI Berlin (2006), JINR Dubna (2007), NECSA South Africa (2008) and CIAE Beijing (2008). It should be pointed out that NPI is widely recognized (at the European level) RESTRAX software package for estimation of characteristic properties of designed performance of neutron scattering devices and their optimization. The unique of the RESTRAX package for neutron ray tracing consists in its possibility of implementing the neutron optical elements (e.g. curved crystals, flat or curved mirrors and supermirrors, any type of collimators etc.) I-2.2. Scientific scope of the project under the CRP The main task related directly to CRP project was participation at the development of focusing monochromator for micro(mini)-focusing SANS device designed by Hokkaido University. The idea of the micro(mini)-focusing SANS device proposed by the Department of Mechanical Intelligence Engineering, Hokkaido University supposes to employ a cylindrically bent perfect (sandwich) monochromator and two curved focusing supermirrors. It represents an inexpensive and compact SANS performance permitting measurements in a large scale momentum transfer which can be installed at a cold neutron source. According to the research plan introduced in the proposal of the CRP research contract, we have prepared several sets of crystal slabs for the CRP partner Hokkaido University. – First, individual silicon ingots were bought and oriented by using X-ray diffractometer for a consequential cutting.

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– Two sets (2x30) 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: 120x20x0.5 mm3 (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. The monochromator in the form of sandwich containing these slabs will be installed at the C1-3 position of the reactor JRRR-3 in Tokai for a prototype of the newly designed mfSANS instrument. The thickness of the slabs is 0.5 mm and all were polished to remove a slightly damaged surface brought about by cutting wires. One set of the crystal slabs will be as a spare one. – Two sets (1x30 and 1x40) 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. – We have carried out calculations related to reflectivity parameters of a strongly curved sandwich type monochromator consisting of thin silicon crystal slabs. – During my stay in Hokkaido University (July 15 – July 25, 2007) a demonstration of manipulation with the sandwich type curved monochromator was carried out. First mock-up test experiments of a time-of –flight type mfSANS was already carried out at a small pulsed cold-neutron source at Hokkaido University and then in JAERI Tokai [13,14]. First results were presented at the ICANS-18 conference in Dongguan City, (China) April 26-29, 2007 and on the related First CRP Coordination Meeting held in Sapporo, July 23-25, 2007. Recent results were presented in the contribution of prof. M. Furusaka at the ICNX 2009 conference in Kuala Lumpur (June 29 – July 1, 2009) and also at the CRP meeting in Kuala Lumpur (July 2-4, 2009). Thanks to the CRP project and meetings, new contacts of mutual collaborations have been also established. Within these collaborations our know-how in the Bragg diffraction optics can be provided to other laboratories, which are interested in employment of focusing devices in their neutron scattering devices (see the next chapter). I-2.3. Work plan for the next 18 months of the CRP – After clarifying the reasons of lower efficiency of the monochromator for minifocusing small-angle neutron scattering (mfSANS) device of Hokkaido University, NPI Rez will prepare new set of crystal wafers. – Construction of two new horizontally focusing monochromators for KAERI Daejeon and about 10 new crystal slabs (namely Si(111) and Si(220))providing different resolution at different monochromator take-off angles. – Construction of complete horizontally focusing monochromator for BARC Mumbai – Preparation of crystal slabs for horizontally and vertically focusing monochromator for BARC Mumbai. The mechanical part will be made in BARC Mumbai. – Construction of horizontally focusing monochromator for Malaysian Nuclear Agency – Monte Carlo simulations of parameters of two instruments in KAERI Daejeon.

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– Presentation of advantageous employment of focusing elements in neutron scattering instruments on international meetings and workshops. I-2.4. Summary – Results obtained till now under CRP – Preparation of the monochromator part for (mini)Focusing SANS device designed and constructed by Hokkaido University (main task of the CRP project) – Construction of focusing monochromator for KAERI Daejeon and 17 crystal slabs for a different monochromator use – Monte Carlo simulations of optimum parameters of neutron scattering devices for JINR Dubna, KAERI Daejeon, CIAE Beijing, NECSA South Africa

I-2.5. References [1] P. Mikula and M. Vrána, Neutron diffraction performance based on multiple Bragg reflection (MBR) monochromator for high-resolution neutron radiography, Biennial Report 2005-2006, Nuclear Physics Institute, v.v.i., AS CR, Řež near Prague, p.41. [2] M.K. Moon, C.H. Lee, V.T. Em, P. Mikula, et al., Optimization of Bent Perfect Si(311)-Crystal Monochromator for Residual Strain/Stress Instrument at HANARO Reactor - Part I, Physica B, 369 (2005) 1-7. [3] M.K. Moon, C.H. Lee, V.T. Em, P. Mikula, et al., Optimization of Bent Perfect Si(220)-Crystal Monochromator for Residual Strain/Stress Instrument- Part II, Physica B- Condensed Matter, 368 (2005) 70-75. [4] P. Mikula, M. Vrána, V. Wagner, D. Lott, Dispersive Monochromators/Analyzers Based on Cylindrically Bent Perfect Crystals (BPC) for High-Resolution TOF Spectrometry, In proceedings of the ICANS-XVII-17th Meeting of the Int. Collaboration on Advanced Neutron Sources, April 25-29, 2005, Santa Fe, New Mexico.

Horizontally focusing monochromator as prepared for JINR Dubna, KAERI Daejeon, BARC Mumbai and

Malaysian Nuclear Agency

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[5] P. Mikula, M. Vrána, D. Lott, V. Wagner, Neutron monochromator based on dispersive double-reflections excited in a cylindrically bent-perfect-crystal (BPC) slab, In Proc. of the ICNS 2005 Conf., Sydney, Nov. 27 – Dec. 2, 2005, Physica B, 385-386 (2006) 1274-1276. [6] S. Kawamura, J. H. Kaneko, H. Fujimoto, Y. Otake, F. Fujita, A.Homma, T. Sawamura, P. Mikula, M. Furusaka, Deformation experiment of piezoelectric single-crystals for neutron-optical-devices, In Proc. of the ICNS 2005 Conf., Sydney, Nov. 27 – Dec. 2, 2005, Physica B, 385-386 (2006) 1277-1279. [7] P. Mikula, M. Vrána, V. Wagner, High-resolution neutron diffraction performance for stress/strain measurements in polycrystalline materials, Zeitschrift für Kristallographie, , Suppl. 23 (2006) 205-210. [8] Y. N. Choi, S.A. Kim, S.K. Kim, S.B. Kim, C.H. Lee, P. Mikula, M. Vrána, Bent perfect crystal (BPC) monochromator at the monochromatic focusing condition, Zeitschrift für Kristallographie, Suppl. 23 (2006) 199-204. [9] P. Mikula, M. Vrána, V. Wagner, M. Furusaka, Multiple reflections (MR) – a new challenge for high-resolution neutron diffractometry and spectrometry, In Proc. of European Workshop on Neutron Optics NOP07, PSI Willigen, March, 5-7, 2007, Nucl. Instrum. Methods in Phys. Research, Section A, A586 (2008) 18-22. [10] P. Mikula, M. Vrána, and V. Wagner , Neutron multiple reflections excited in cylindrically bent perfect crystals and their possible use for high-resolution neutron scattering, 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 137/2008, pp. 459-470. [11] R.C. Wimpory, P. Mikula, J. Saroun, T. Poeste, Junghong Li, M Hoffman nand 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 (2008) 16-19. [12] R.C. Wimpory, P. Mikula, J. Saroun, 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 2007, HMI Berlin, Edited by U. Stahnke, A. Brandt and H.A. Graf, April 2008, HMI-B 617, ISSN 0936-0891. [13] 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 26-29,2007, Dongguan, China. [14] 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: Exp. Reports 15 (2008), Report Number: 655, Tokyo University.