Neutron resonance transmission imaging for 3D elemental mapping at the ISIS spallation neutron source

Abstract

We demonstrate for the first time the viability of a three-dimensional (3D) elemental imaging technique based on Neutron Resonance Transmission Imaging (NRTI), which is a neutron technique based on the presence of a resonance structure in the neutron-induced reaction cross sections. These resonances allow the identification of elements and isotopes within an object in a non-destructive manner. A dedicated set-up on the INES (Italian Neutron Experimental Station) beamline of the ISIS spallation neutron source was employed for the experiments. An early mediaeval disc fibula from the Hungarian National Museum in Budapest was used for our demonstration. The methodology and analysis procedures are described and the results obtained from the reconstruction of the 3D NRTI elemental image of the ancient object are compared with the results obtained from other neutron-based 3D imaging techniques

Non-contact measurement of partial gas pressure and distribution of elemental composition using energy-resolved neutron imaging

“…Recent developments of neutron detectors with ∼55 µm spatial and 20 ns -500 µs temporal resolution have enabled neutron resonance imaging with spatial resolution greater than ∼100 µm. 19,28,29 Resonance imaging experiments have been previously performed with solid materials using resonances up to ∼10 keV in energy [15][16][17][18][19][20][21][22][23][24] and we extend these studies to imaging gaseous substances.…”

“…This allows spatially-resolved imaging of features related to microstructure variation such as texture and mosaicity, [7][8][9][10] residual strain 7,[10][11][12][13] and phase distributions, 14 when thermal and cold neutrons are used. Studies that employ resonances appearing in the epithermal range of energies have been also reported for the investigation of elemental composition [15][16][17][18][19][20][21] and remote measurement of temperature. [22][23][24] Energy-resolved measurements can be conducted at reactor sources using velocity selectors 25 and crystal monochromators 26 with energy resolutions (∆E/E) of ∼15% and ∼3%, respectively.…”

“…At current facilities the measurable energy range is typically limited to less than ∼10 4 eV by the width of the neutron pulse, the available flux, and by the level of background signal. [17][18][19][20][21][22][23][24] Thus current opportunities are best served for nuclides with resonances between ∼0.1 eV and ∼10 keV energies. Tabulated attenuation cross sections 27 exist for the majority of isotopes and can be used to evaluate experiment feasibility to resolve a particular element in a specific sample.…”

“…By contrast pulsed spallation neutron sources, which typically employ time of flight technique to resolve neutron energy, routinely offer energy resolution to sub-percent levels 4 and extend the spectral range to epithermal neutrons in excess of 10 keV. [15][16][17][18][19][20][21][22][23][24] In the region of ∼1-10 5 eV many elements exhibit isotope-specific resonances that exist over narrow energy ranges specific to a particular isotope. Their existence results in sharp decreases in neutron transmission at discrete energies that indicate the presence of isotopes along the neutron path.…”

“…15,16,20 However recent development of fast detection devices with 55 µm detector pixel size enables mapping the distribution of elements (including tomographic 3-dimensional imaging) and temperature in a solid sample with a ∼100 µm resolution.…”