scholarly journals A Photo and Thermally Stimulated Luminescence Study of BaCl2:Eu2+ with Application to Neutron Imaging

2021 ◽  
Author(s):  
◽  
Jeremy Robinson
Keyword(s):  
Gas Flow ◽  
Glass Ceramics ◽  
Barium Chloride ◽  
Neutron Imaging ◽  
Structural Defects ◽  
Thermally Stimulated Luminescence ◽  
Luminescence Study ◽  
Alkaline Earth Elements ◽  
Imaging Plates ◽  
Work Done

<p>This thesis presents the results of a photo and thermally stimulated luminescence study of europium-doped barium chloride in relation to its potential application as a storage phosphor in glass ceramics for radiation imaging, particularly for neutron imaging. Previous work done on lithium borate (LiBO) glasses containing BaCl2:Eu2+ nanocrystals at Victoria University of Wellington had demonstrated comparable imaging capability with commercially available BaFBr:Eu2+ based imaging plates, though the sensitivity and spatial resolution were inferior to that material, and there was a substantial afterglow during the read-out process which degraded any image. These problems are addressed here. The effect of various different co-dopants on the storage properties was examined using the thermally stimulated luminescence (TSL) technique, with dopants primarily chosen from the alkali and alkaline earth elements. The resulting glow curves have been analysed to determine the activation energies associated with the various traps, and tentative assignments of structural defects to the various glow curve peaks are proposed. It was found that Li+ and Na+ gave small increases (20% and 50% respectively) in efficiency, though other dopants tended to reduce the overall output. In particular, K+ and Rb+ were found to substantially reduce the output efficiency. It was found that Li+ co-doped BaCl2:Eu2+ contained thermally unstable traps which at room temperature could result in the observed afterglow in LiBO/BaCl2 glass ceramics through a read-out induced phototransfer process. The experimental measurements required substantial hardware and software development of the existing VUW facilities for TSL, and these improvements are also described here. The most significant improvements are an extension of the operating range at the lower end of the existing TSL spectrometer to -50 degrees C through a cooled gas flow system, and the engineering of a completely new system to record TSL from 25 K to 400 K.</p>

scholarly journals A Photo and Thermally Stimulated Luminescence Study of BaCl2:Eu2+ with Application to Neutron Imaging

2021 ◽  
Author(s):  
◽  
Jeremy Robinson
Keyword(s):  
Gas Flow ◽  
Glass Ceramics ◽  
Barium Chloride ◽  
Neutron Imaging ◽  
Structural Defects ◽  
Thermally Stimulated Luminescence ◽  
Luminescence Study ◽  
Alkaline Earth Elements ◽  
Imaging Plates ◽  
Work Done

<p>This thesis presents the results of a photo and thermally stimulated luminescence study of europium-doped barium chloride in relation to its potential application as a storage phosphor in glass ceramics for radiation imaging, particularly for neutron imaging. Previous work done on lithium borate (LiBO) glasses containing BaCl2:Eu2+ nanocrystals at Victoria University of Wellington had demonstrated comparable imaging capability with commercially available BaFBr:Eu2+ based imaging plates, though the sensitivity and spatial resolution were inferior to that material, and there was a substantial afterglow during the read-out process which degraded any image. These problems are addressed here. The effect of various different co-dopants on the storage properties was examined using the thermally stimulated luminescence (TSL) technique, with dopants primarily chosen from the alkali and alkaline earth elements. The resulting glow curves have been analysed to determine the activation energies associated with the various traps, and tentative assignments of structural defects to the various glow curve peaks are proposed. It was found that Li+ and Na+ gave small increases (20% and 50% respectively) in efficiency, though other dopants tended to reduce the overall output. In particular, K+ and Rb+ were found to substantially reduce the output efficiency. It was found that Li+ co-doped BaCl2:Eu2+ contained thermally unstable traps which at room temperature could result in the observed afterglow in LiBO/BaCl2 glass ceramics through a read-out induced phototransfer process. The experimental measurements required substantial hardware and software development of the existing VUW facilities for TSL, and these improvements are also described here. The most significant improvements are an extension of the operating range at the lower end of the existing TSL spectrometer to -50 degrees C through a cooled gas flow system, and the engineering of a completely new system to record TSL from 25 K to 400 K.</p>

Lithium borate glass ceramics as thermal neutron imaging plates

2006 ◽  
Vol 6 (3) ◽  
pp. 389-392 ◽  
Author(s):  
G.A. Appleby ◽  
C.M. Bartle ◽  
G.V.M. Williams ◽  
A. Edgar
Keyword(s):  
Thermal Neutron ◽  
Borate Glass ◽  
Glass Ceramics ◽  
Neutron Imaging ◽  
Lithium Borate ◽  
Lithium Borate Glass ◽  
Imaging Plates ◽  
Thermal Neutron Imaging

scholarly journals Performance assessment of imaging plates for the JHR transfer Neutron Imaging System

2018 ◽  
Vol 170 ◽  
pp. 04021
Author(s):  
E. Simon ◽  
P. Guimbal
Keyword(s):  
Performance Assessment ◽  
Dynamic Range ◽  
Imaging System ◽  
Computed Radiography ◽  
High Sensitivity ◽  
High Dynamic Range ◽  
Neutron Imaging ◽  
Imaging Plate ◽  
Intimate Contact ◽  
Imaging Plates

The underwater Neutron Imaging System to be installed in the Jules Horowitz Reactor (JHR-NIS) is based on a transfer method using a neutron activated beta-emitter like Dysprosium. The information stored in the converter is to be offline transferred on a specific imaging system, still to be defined. Solutions are currently under investigation for the JHR-NIS in order to anticipate the disappearance of radiographic films commonly used in these applications. We report here the performance assessment of Computed Radiography imagers (Imaging Plates) performed at LLB/Orphée (CEA Saclay). Several imaging plate types are studied, in one hand in the configuration involving an intimate contact with an activated dysprosium foil converter: Fuji BAS-TR, Fuji UR-1 and Carestream Flex XL Blue imaging plates, and in the other hand by using a prototypal imaging plate doped with dysprosium and thus not needing any contact with a separate converter foil. The results for these imaging plates are compared with those obtained with gadolinium doped imaging plate used in direct neutron imaging (Fuji BAS-ND). The detection performances of the different imagers are compared regarding resolution and noise. The many advantages of using imaging plates over radiographic films (high sensitivity, linear response, high dynamic range) could palliate its lower intrinsic resolution.

An imaging-plate detector for small-angle neutron scattering

2000 ◽  
Vol 33 (5) ◽  
pp. 1253-1261 ◽  
Author(s):  
Y. T. Cheng ◽  
D. F. R. Mildner ◽  
H. H. Chen-Mayer ◽  
V. A. Sharov ◽  
C. J. Glinka
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Imaging Techniques ◽  
Neutron Imaging ◽  
Small Samples ◽  
Imaging Plate ◽  
Position Sensitive ◽  
Transfer Method ◽  
Imaging Plates

Small-angle neutron scattering (SANS) measurements have been performed on long-flight-path pinhole-collimation SANS instruments using, as a two-dimensional position-sensitive detector, both a neutron imaging plate, incorporating gadolinium, and a two-step transfer method, with dysprosium foil as the image transfer medium. The measurements are compared with corresponding data taken using conventional position-sensitive gas proportional counters on the SANS instruments in order to assess the viability of the imaging techniques. The imaging plates have pixel sizes of about two orders of magnitude smaller than those of the gas proportional counter. The reduced pixel size provides definite advantages over the gas counter in certain specific situations, namely when limited space necessitates a short sample-to-detector distance, when only small samples (comparable in size to the detector pixels) are available, or when used in conjunction with focusing beam optics.

A neutron diffractometer for biological macromolecules using neutron imaging plates

1997 ◽  
Vol 241-243 ◽  
pp. 207-209 ◽  
Author(s):  
S Fujiwara ◽  
Y Karasawa ◽  
I Tanaka ◽  
Y Minezaki ◽  
Y Yonezawa ◽  
...  
Keyword(s):  
Neutron Imaging ◽  
Biological Macromolecules ◽  
Neutron Diffractometer ◽  
Imaging Plates

Neutron Image Restoration by Combining Richardson-Lucy With Steering Kernel

2013 ◽  
Author(s):  
Shuang Qiao ◽  
Qiao Wang ◽  
Jipeng Huang
Keyword(s):  
Imaging System ◽  
Signal To Noise Ratio ◽  
Neutron Imaging ◽  
Low Contrast ◽  
Image Characteristics ◽  
Restoration Algorithm ◽  
Degraded Image ◽  
Neutron Image ◽  
Noise Amplification ◽  
Work Done

Neutron image obtained from a small digital neutron imaging system, always has characteristics of low contrast, blurred edges and serious noise. It is disadvantageous to further analyse information about the sample’s internal structure, so it is essential for the observer to process the degraded image to improve its visual quality. In order to avoid the noise amplification problem of the original Richardson-Lucy (R-L) algorithm, which is adopted to recover degraded image, a restoration algorithm by combining R-L algorithm with Steering Kernel (S-K) algorithm for neutron image is presented in this paper. First S-K algorithm is applied to restrain the noise of the blurred noisy neutron image, as well as improving the signal-to-noise ratio of the image, and then R-L algorithm is used to reconstruct the blurred noisy image. The proposed algorithm is able to make up for the deficiency of R-L algorithm in dealing with the noise amplification problem, which is caused by the repeated iteration, while retaining the details of the image characteristics as much as possible. Comparative experimental results show that the algorithm can obtain satisfactory restoration visual effect for neutron image. The details of the work done are described in this paper.

Time-resolved luminescence study of CaF2:Eu2+ nanocrystals in glass-ceramics

2005 ◽  
Vol 112 (1-4) ◽  
pp. 161-165 ◽  
Author(s):  
M. Itoh ◽  
T. Sakurai ◽  
T. Yamakami ◽  
J. Fu
Keyword(s):  
Glass Ceramics ◽  
Time Resolved ◽  
Luminescence Study

Effect of growth temperature on the microstructure of the nucleation layers of GaN grown by MOCVD on (1120) sapphire

2002 ◽  
Vol 743 ◽  
Author(s):  
T. Wojtowicz ◽  
P. Ruterana ◽  
M. E. Twigg ◽  
R. L. Henry ◽  
D. D. Koleske ◽  
...  
Keyword(s):  
High Temperature ◽  
Structural Analysis ◽  
Growth Temperature ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Nucleation Mechanism ◽  
Structural Defects ◽  
Orientation Relationships ◽  
Island Growth ◽  
Work Done

AbstractMost of the work done on GaN has taken into account layers grown on the (0001) sapphire plane. However one would expect the growth on the (1120) plane to lead to different structural defects. As has been shown, in one direction, the mismatch is rather small. In this work, we have carried out structural analysis of nucleation layers grown at temperatures ranging from 600°C to 1100°C. It is shown that for many of the structural parameters, such as the orientation relationships, the layer morphology and the nucleation mechanism critically depend on the growth temperature. At the lowest temperatures, the growth is completely three dimensional with a mixture of the two traditional orientation relationships, but the coalescence thickness is small. In a next step, the A orientation relationship predominates and the layer roughness tends to slightly decrease. This orientation is never perfect, and there is always 1.5° misorientation to the same direction in sapphire, whereas the B orientation is always perfect. At an intermediate temperature, island growth is predominant, whereas towards the high temperature end the B orientation becomes predominant. For the highest growth temperatures, the nucleated layers are completely flat and with the B orientation, although they contain a quite large number of defects such as inversion domains.

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