Attenuation correction for multi-anvil high-pressure apparatus
J. Abe1#, K. Komatsu2, H. Arima3, A. Sano4, T. Hattori5 and H. Kagi2
1CROSS-Tokai, Tokai, Ibaraki 319-1106, Japan
Geochemical Research Center,TheUniversity of Tokyo, Hongo, Tokyo 113-0033, Japan
3
Institute for Materials Research, Tohoku university, Katahira, Miyagi 980-0812, Japan
4
QuBS, JAEA, Tokai, Ibaraki 319-1195, Japan
5J-PARC Center, JAEA, Tokai, Ibaraki 319-1195, Japan2# a corresponding author: E-mail j_abe@cross.or.jp
High Pressure Neutron Diffractometer “PLANET (Pressure Leading Apparatus for
Neutron Diffraction)” [1] has been constructed at BL11 in J-PARC. “PLANET” is equippedwith a multi-anvil high-pressure apparatus which compresses sample from six directions. In
neutron experiments using a high-pressure apparatus, the neutron beam are attenuated bycomponents of a high-pressure cell assembly. This attenuation causes the decrease of the peakintensities in a neutron diffraction pattern from the ideal values. A correction for theattenuation is therefore required for quantitative studies such as structure refinements. In thisstudy, we developed a program to calculate the attenuation correction coefficient for
multi-anvil high-pressure apparatus, and verified the results by determining peak intensities ofa neutron diffraction pattern obtained with a cubic-anvil high-pressure apparatus andcomparing them with those from a pattern obtained using a standard sample holder.
The attenuation factor (A) is calculated using attenuation coefficient (μ) of a component,
and neutron path length (t). The μ is dependent on the wavelength, and t is dependent on thescattering angle. A program for the calculation of A was written in FORTRAN 90/95. The t isevaluated via a ray tracing method or vector calculation, and the μ values are obtained
experimentally.
For verification, neutron diffraction experiments were performed for a standard powder
sample, in and out of another small-type multi-anvil high-pressure apparatus (Palm Cubicmulti-anvil apparatus)[2] at BL19 “TAKUMI” in J-PARC. The Al2O3 powder was set in thecenter of the gasket of the Palm Cubic apparatus. The neutron diffraction pattern of Al2O3
powder in a standard sample holder (vanadium can) was also measured. The attenuation
factor was obtained from peak intensity ratio of Al2O3 powder between using a high-pressure
apparatus and a standard sample holder.
The attenuation factors calculated using the program showed good agreement with theresult evaluated experimentally. This confirms that the program developed in this study
enabled the attenuation effect to be properly corrected. In the presentation, we will talk about
the details of the program and the result. In addition, the attenuation value evaluated for theresults obtained at “PLANET” will be shown.
References[1] H. Arima, T. Hattori, K. Komatsu, J. Abe, W. Utsumi, H. Kagi, A. Suzuki, K. Suzuya, T.
Kamiyama, M. Arai T. Yagi, J. Phys.: Conf. Ser. 215, 012025 (2010).
[2] J. Abe, M. Arakawa, T. Hattori, H. Arima, H. Kagi, K. Komatsu, A. Sano-Furukawa, Y.
Uwatoko, K. Matsubayashi, S. Harjo, A. Moriai, T. Ito, K. Aizawa, M. Arai, and W. Utsumi,
Rev. Sci. Instrum. 81, 043910 (2010).