Energy-resolved neutron tomography of an unconventional cultured pearl at a pulsed spallation source using a microchannel plate camera

Abstract A non-destructive neutron analysis technique performed at the IMAT beamline of the STFC (Science and Technology Facility Council), UK, is presented. In this experiment, neutrons of different energy have been exploited to obtain a tomographic reconstruction of a biomineralic sample, more specifically a cultured pearl, by using a time-resolving pixel camera, the MicroChannel Plate (MCP) detector, utilizing an array of 2 × 2 Timepix readout chips. The MCP camera is capable of energy-resolved two-dimensional mapping of neutron transmission with a spatial resolution of ~ 55 μm. By using a Simultaneous Iterative Reconstruction Technique (SIRT), virtual sections of the internal part of the sample have been created, thus revealing several features inside its bulk. The crystallographic phase map via Bragg edge analysis, showing a phase fraction distribution on the entire specimen, has been generated as well. Finally, 3D volume rendering of the pearl is presented.

[1]  Jan Sijbers,et al.  Fast and flexible X-ray tomography using the ASTRA toolbox. , 2016, Optics express.

[2]  Lorenzo Moneta,et al.  ROOT - A C++ framework for petabyte data storage, statistical analysis and visualization , 2009, Comput. Phys. Commun..

[3]  B. Münch,et al.  Stripe and ring artifact removal with combined wavelet--Fourier filtering. , 2009, Optics express.

[4]  Jason McPhate,et al.  Detection efficiency, spatial and timing resolution of thermal and cold neutron counting MCP detectors , 2009 .

[5]  D. Penumadu,et al.  3D Mapping of Crystallographic Phase Distribution using Energy‐Selective Neutron Tomography , 2014, Advanced materials.

[6]  P. Gilbert.  Iterative methods for the three-dimensional reconstruction of an object from projections. , 1972, Journal of theoretical biology.

[7]  Daniel Chateigner,et al.  Mollusc shell microstructures and crystallographic textures , 2000 .

[8]  J. V. Vallerga,et al.  High Resolution Photon Counting With MCP-Timepix Quad Parallel Readout Operating at $> 1~{\rm KHz}$ Frame Rates , 2013, IEEE Transactions on Nuclear Science.

[9]  Lyndon Edwards,et al.  Characterization of textured materials by TOF transmission , 2006 .

[10]  Jason McPhate,et al.  Transmission Bragg edge spectroscopy measurements at ORNL Spallation Neutron Source , 2010 .

[11]  Rafael Ballabriga,et al.  Timepix, a 65k programmable pixel readout chip for arrival time, energy and/or photon counting measurements , 2007 .

[12]  Giuseppe Gorini,et al.  Materials analysis opportunities on the new neutron imaging facility IMAT@ISIS , 2016 .

[13]  Jason McPhate,et al.  Optimization of Timepix count rate capabilities for the applications with a periodic input signal , 2014 .

[14]  Philip J. Withers,et al.  Time-of-flight neutron transmission diffraction , 2001 .

[15]  Kenneth Scarratt,et al.  Characteristics of Nuclei in Chinese Freshwater Cultured Pearls , 2000 .

[16]  T. Sumitomo,et al.  The toughening mechanism of nacre and structural materials inspired by nacre , 2011, Science and technology of advanced materials.

[17]  Michael S. Krzemnicki,et al.  New developments in cultured pearl production: use of organic and baroque shell nuclei , 2013 .