RAD
RAD – Static/dynamic thermal-neutron and X-ray imaging station
Instrument responsible: Zoltán Kis
Contact: rad@bnc.hu
Video introduction (short, longer)
Radiography utilizes the transmission of photons or neutrons to obtain information on the structure and/or inner processes of a given object. The thermal neutron imaging facility, RAD is served by an in-pile, Cd-covered pin-hole-type collimator for neutron and gamma radiation. The facility offers two measurement positions along the neutron beam path with a beam diameter of ~200 mm, used for dynamic (DNR) and for static (SNR) imaging with a measured L/D ratio of ~250. Options are provided to use beam filters made of boron-containing rubber and lead bricks, resulting in a significant modification of the beam energy distribution, giving a fast/thermal neutron flux ratio of 77 instead of 0.6. The RAD facility is also equipped with an optional X‑ray tube, allowing dual-modality imaging. Two motorized sample stages, one for small and one for large samples (with a maximum load up to 250 kg) are available to support the investigated objects. A sapphire-crystal-based filter is under installation to suppress fast neutrons.
The image detection of the RAD station now relies on digital imaging equipment being able to carry out 2D and 3D imaging using suitable scintillation screens. The spatial resolutions of the available screens are as follows: scintillation screens for neutron radiography with resolution between 70-250 μm; intensifying screens for X-ray radiography with a resolution of 100-200 μm. For better flexibility, an option is provided to apply larger or smaller fields of views (FOV) with lower and higher spatial resolution, respectively. The static radiography and tomography are accomplished by a new, large area sCMOS camera. Here altogether three different optical systems can be set up using the available lenses with 50 mm, 105 mm and 300 mm fixed focal lengths, interchangeably coupled to the digital camera, giving the different FOVs.
For the manipulation, reconstruction, and visualization of the 3D neutron and X-ray datasets (i.e. the tomographic images), the latest Fiji-ImageJ, Octopus 8.9, and VGStudio MAX 3.2 software packages are used.
Dynamic radiography is performed by means of a low-light-level TV camera with a fast imaging cycle, making possible real-time imaging. The zoom optics coupled to the camera provides a variable field of view. The two cameras can be used interchangeably in a light-tight camera box equipped with a rail system providing the necessary optical path lengths.
In addition to the cameras, the photo-luminescent imaging plate (IP) technique is also available for high-resolution X-ray and neutron radiation detection with transfer method using In and Dy (100 μm) foils. The exposed IP-s are read out by a BAS 2500 image plate reader equipped with the AIDA image processing software.
Beam energy distribution: |
radial thermal-neutron channel |
Thermal-equivalent flux at target: |
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Thermal-to-epithermal flux ratio Fth/Fepi |
51 |
Fast neutron flux (E>2.1MeV, measured with the Ni-58(n,p)Co-58 reaction) |
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Collimator ratio (L/D) : |
250 |
Gamma dose rate: |
8.5 Gy/h |
X-ray sources: |
5-300 keV; 5-10 mA |
Field of view (useful): |
41×34 mm2, 110×93 mm2 or Ø200 mm |
Scintillator screens (thickness): |
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Mirror: |
Al coated quartz mirror set in 45° to the beam |
Optics: |
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Imaging detectors : |
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Spatial resolution: |
70‑250 μm depending on the FOV and scintillators |
Exposure times: |
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Sample stages: |
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Table 1. Specifications of the RAD facility
Figure 1. The 3D layout of the RAD facility
Figure 2. The optics of the detector system
Figure 3. The digital imaging system of RAD
Figure 4. The turntable for small objects with concrete test bars (left). Porosity analysis with VG Studio MAX (right)
References:
Z Kis, L Szentmiklósi, T Belgya, M Balaskó, LZ Horváth, B Maróti. Neutron based imaging and element-mapping at the Budapest Neutron Centre, Physics Procedia. 69 (2015) 40 – 47. DOI: 10.1016/j.phpro.2015.07.005
Szentmiklósi László, Kis Zoltán, Belgya Tamás, Maróti Boglárka, Horváth László Zoltán, Papp Mariann: Roncsolásmentes képalkotás neutronokkal és röntgensugárzással a Budapesti Neutron Centrumban, Fizikai Szemle 67/7-8 (2017) 240-244.
V. Szilágyi, Z. Kis, L. Szentmiklósi: Neutron Imaging for Archaeometry / A neutronos képalkotás archeometriai alkalmazása, Archeometriai Műhely 2016/XIII./3. (2017) 157-172
R. Zboray, R. Adams, Z. Kis: Scintillator screen development for fast neutron tomography and its application at the beamline of the 10 MW BNC research reactor, Appl Radiat Isot. 2018 Oct;140:215-223. doi: 10.1016/j.apradiso.2018.07.016