Position sensitive ultracold neuton detectors

Les neutrons rebondissant sur un miroir horizontal parfait se comportent comme des objets quantiques dans le champ de pesanteur terrestre. Leur énergie prend des valeurs discrètes, contrairement à une balle de tennis rebondissant à l'échelle macroscopique. L'étude des états quantiques des neutrons, et surtout des transitions résonantes entre deux états, permettrait de poser des limites sur les paramètres de certains modèles de la physique fondamentale. Le spectromètre GRANIT, installé à l'Institue Laue-Langevin (Grenoble, France), dispose de modules magnétiques pour induire des transitions résonantes aux neutrons et les étudier. Un des modes de fonctionnement nécessite d'un détecteur de neutrons sensible à la position, qui a été conçu avec des couches minces de conversion de neutrons en 10B et de scintillateur en ZnS(Ag), ainsi qu'un réseau de fibres optiques pour repérer la position d'impact des neutrons sur le détecteur. Des couches minces ont été élaborées par pulvérisation assistée par plasma micro-onde, leurs structures caractérisées par MEB et leurs performances de scintillation testées par un tube photomultiplicateur. L'efficacité de scintillation en fonction de la concentration d'argent a été étudiée, grâce à un procédé de dopage d'argent in situ. Un algorithme d'identification des photoélectrons a également été mis en place sur le réseau de fibres optiques pour reconstruire le barycentre des neutrons incidents.Bouncing neutrons on a perfect horizontal mirror become quantum objects in Earth's gravitational field. Their energy takes discrete values, contrary to a bouncing ball at a macroscopic scale. The study of the neutron quantum states, and especially the resonant transitions between two states, has the prospect to constrain parameters of certain models of nowadays fundamental physics. The GRANIT spectrometer, housed in the Laue-Langevin Institute (Grenoble, France), is equipped with magnetic field generator modules to induce resonant transitions to study them. One of its operating mode requires a position-sensitive neutron detector, which is designed as a combination of thin films of neutron conversion material 10B and scintillator ZnS(Ag), as well as an optical fibre matrix to determine the positon of incoming neutrons. The thin films were deposited by sputter deposition assisted by microwave plasma. Their structure was examined by SEM and their scintillation performance tested by a photomultiplier tube. The scintillation efficiency in relation to Ag dopant in ZnS was studied, thanks to a procedure of in situ Ag doping. An algorithm capable of identifying photoelectrons was also installed on the optical fibre matrix to reconstruct the barycentre of incoming neutrons

Détecteur de neutrons ultra-froids sensible à la position

Bouncing neutrons on a perfect horizontal mirror become quantum objects in Earth's gravitational field. Their energy takes discrete values, contrary to a bouncing ball at a macroscopic scale. The study of the neutron quantum states, and especially the resonant transitions between two states, has the prospect to constrain parameters of certain models of nowadays fundamental physics. The GRANIT spectrometer, housed in the Laue-Langevin Institute (Grenoble, France), is equipped with magnetic field generator modules to induce resonant transitions to study them. One of its operating mode requires a position-sensitive neutron detector, which is designed as a combination of thin films of neutron conversion material 10B and scintillator ZnS(Ag), as well as an optical fibre matrix to determine the positon of incoming neutrons. The thin films were deposited by sputter deposition assisted by microwave plasma. Their structure was examined by SEM and their scintillation performance tested by a photomultiplier tube. The scintillation efficiency in relation to Ag dopant in ZnS was studied, thanks to a procedure of in situ Ag doping. An algorithm capable of identifying photoelectrons was also installed on the optical fibre matrix to reconstruct the barycentre of incoming neutrons.Les neutrons rebondissant sur un miroir horizontal parfait se comportent comme des objets quantiques dans le champ de pesanteur terrestre. Leur énergie prend des valeurs discrètes, contrairement à une balle de tennis rebondissant à l'échelle macroscopique. L'étude des états quantiques des neutrons, et surtout des transitions résonantes entre deux états, permettrait de poser des limites sur les paramètres de certains modèles de la physique fondamentale. Le spectromètre GRANIT, installé à l'Institue Laue-Langevin (Grenoble, France), dispose de modules magnétiques pour induire des transitions résonantes aux neutrons et les étudier. Un des modes de fonctionnement nécessite d'un détecteur de neutrons sensible à la position, qui a été conçu avec des couches minces de conversion de neutrons en 10B et de scintillateur en ZnS(Ag), ainsi qu'un réseau de fibres optiques pour repérer la position d'impact des neutrons sur le détecteur. Des couches minces ont été élaborées par pulvérisation assistée par plasma micro-onde, leurs structures caractérisées par MEB et leurs performances de scintillation testées par un tube photomultiplicateur. L'efficacité de scintillation en fonction de la concentration d'argent a été étudiée, grâce à un procédé de dopage d'argent in situ. Un algorithme d'identification des photoélectrons a également été mis en place sur le réseau de fibres optiques pour reconstruire le barycentre des neutrons incidents

Détecteur de neutrons ultra-froids sensible à la position

Bouncing neutrons on a perfect horizontal mirror become quantum objects in Earth's gravitational field. Their energy takes discrete values, contrary to a bouncing ball at a macroscopic scale. The study of the neutron quantum states, and especially the resonant transitions between two states, has the prospect to constrain parameters of certain models of nowadays fundamental physics. The GRANIT spectrometer, housed in the Laue-Langevin Institute (Grenoble, France), is equipped with magnetic field generator modules to induce resonant transitions to study them. One of its operating mode requires a position-sensitive neutron detector, which is designed as a combination of thin films of neutron conversion material 10B and scintillator ZnS(Ag), as well as an optical fibre matrix to determine the positon of incoming neutrons. The thin films were deposited by sputter deposition assisted by microwave plasma. Their structure was examined by SEM and their scintillation performance tested by a photomultiplier tube. The scintillation efficiency in relation to Ag dopant in ZnS was studied, thanks to a procedure of in situ Ag doping. An algorithm capable of identifying photoelectrons was also installed on the optical fibre matrix to reconstruct the barycentre of incoming neutrons.Les neutrons rebondissant sur un miroir horizontal parfait se comportent comme des objets quantiques dans le champ de pesanteur terrestre. Leur énergie prend des valeurs discrètes, contrairement à une balle de tennis rebondissant à l'échelle macroscopique. L'étude des états quantiques des neutrons, et surtout des transitions résonantes entre deux états, permettrait de poser des limites sur les paramètres de certains modèles de la physique fondamentale. Le spectromètre GRANIT, installé à l'Institue Laue-Langevin (Grenoble, France), dispose de modules magnétiques pour induire des transitions résonantes aux neutrons et les étudier. Un des modes de fonctionnement nécessite d'un détecteur de neutrons sensible à la position, qui a été conçu avec des couches minces de conversion de neutrons en 10B et de scintillateur en ZnS(Ag), ainsi qu'un réseau de fibres optiques pour repérer la position d'impact des neutrons sur le détecteur. Des couches minces ont été élaborées par pulvérisation assistée par plasma micro-onde, leurs structures caractérisées par MEB et leurs performances de scintillation testées par un tube photomultiplicateur. L'efficacité de scintillation en fonction de la concentration d'argent a été étudiée, grâce à un procédé de dopage d'argent in situ. Un algorithme d'identification des photoélectrons a également été mis en place sur le réseau de fibres optiques pour reconstruire le barycentre des neutrons incidents

Détecteur de neutrons ultra-froids sensible à la position

Bouncing neutrons on a perfect horizontal mirror become quantum objects in Earth's gravitational field. Their energy takes discrete values, contrary to a bouncing ball at a macroscopic scale. The study of the neutron quantum states, and especially the resonant transitions between two states, has the prospect to constrain parameters of certain models of nowadays fundamental physics. The GRANIT spectrometer, housed in the Laue-Langevin Institute (Grenoble, France), is equipped with magnetic field generator modules to induce resonant transitions to study them. One of its operating mode requires a position-sensitive neutron detector, which is designed as a combination of thin films of neutron conversion material 10B and scintillator ZnS(Ag), as well as an optical fibre matrix to determine the positon of incoming neutrons. The thin films were deposited by sputter deposition assisted by microwave plasma. Their structure was examined by SEM and their scintillation performance tested by a photomultiplier tube. The scintillation efficiency in relation to Ag dopant in ZnS was studied, thanks to a procedure of in situ Ag doping. An algorithm capable of identifying photoelectrons was also installed on the optical fibre matrix to reconstruct the barycentre of incoming neutrons.Les neutrons rebondissant sur un miroir horizontal parfait se comportent comme des objets quantiques dans le champ de pesanteur terrestre. Leur énergie prend des valeurs discrètes, contrairement à une balle de tennis rebondissant à l'échelle macroscopique. L'étude des états quantiques des neutrons, et surtout des transitions résonantes entre deux états, permettrait de poser des limites sur les paramètres de certains modèles de la physique fondamentale. Le spectromètre GRANIT, installé à l'Institue Laue-Langevin (Grenoble, France), dispose de modules magnétiques pour induire des transitions résonantes aux neutrons et les étudier. Un des modes de fonctionnement nécessite d'un détecteur de neutrons sensible à la position, qui a été conçu avec des couches minces de conversion de neutrons en 10B et de scintillateur en ZnS(Ag), ainsi qu'un réseau de fibres optiques pour repérer la position d'impact des neutrons sur le détecteur. Des couches minces ont été élaborées par pulvérisation assistée par plasma micro-onde, leurs structures caractérisées par MEB et leurs performances de scintillation testées par un tube photomultiplicateur. L'efficacité de scintillation en fonction de la concentration d'argent a été étudiée, grâce à un procédé de dopage d'argent in situ. Un algorithme d'identification des photoélectrons a également été mis en place sur le réseau de fibres optiques pour reconstruire le barycentre des neutrons incidents

A Double-Adaptive Adjustment Algorithm for Ionospheric Tomography

A double-adaptive adjustment algorithm (DAAA) is proposed to reconstruct three-dimensional ionospheric electron density (IED) distribution. In the DAAA method, the relaxation factor of the multiplicative algebraic reconstruction technique (MART) is first adaptively adjusted by introducing adaptive MART (AMART). To avoid the voxels without any rays traversing them becoming dependent on the initial IED values, smoothing constraints are generally imposed on the adaptive multiplicative algebraic reconstruction technique (AMART). In general, the elements of the smoothing matrices are invariant in the iterative process. They affect the accuracy and efficiency of the IED inversion. To overcome the above limitation, the adaptive adjustments of the constrained matrix elements are subsequently carried out. Both numerical simulation and actual global navigation satellite system (GNSS) experimental results validate that the accuracy and efficiency of ionospheric tomography have been improved by the DAAA method. Finally, the new algorithm is applied to reconstruct the three-dimensional structure of the ionosphere during different geomagnetic activities. The comparisons show that the vertical profiles of the DAAA method are in agreement with those recorded from the ionosonde, and the inverted vertical total electron content (VTEC) of the DAAA method also agrees with the ionospheric products of center for orbit determination in Europe (CODE) during geomagnetic quiet and geomagnetic storms. The comparisons confirm the reliability and superiority of the DAAA method

Spatial-spectral dual path hyperspectral image super-resolution reconstruction network based on spectral response functions

Recently, hyperspectral image (HSI) super-resolution (SR) techniques based on deep learning have been actively developed. However, most hyperspectral image super-resolution reconstruction methods usually use all spectral bands simultaneously, leading to a mismatch of spectral properties between reconstructed HSI bands. Therefore, we proposed a new method of spatial-spectral dual path residual network (SGDPRN) based on spectral response function (SRF) to address the above problem. The SGDPRN is composed of the SRF guided grouping part, the spatial-spectral feature extraction part, and the final reconstruction part. Firstly, the reconstructed features for different spectral ranges are identified separately using SRF as a guide. Then, based on the grouping results, a spatial-spectral dual-path residual block is used to explore the spatial and spectral features by the designed parallel structure simultaneously. The spatial path is designed to extract sharp edges and realistic textures, and the spectral path is designed to model inter-spectral correlations to refine spectral features. At last, the third block of SGDPRN concatenates features of all groups and finishes the reconstruction of HSISR. QUST-1 satellite images have been applied in experiments, and the results showed that SGDPRN produced a higher peak signal to noise ratio, structural similarity metric, correlation coefficient, and lower spectral angle mapper, root mean square error than the other methods. This demonstrates that our method can effectively maintain the correlation of spectral bands while improving the spatial resolution

A New Algorithm for Ill-Posed Problem of GNSS-Based Ionospheric Tomography

Ill-posedness of GNSS-based ionospheric tomography affects the stability and the accuracy of the inversion results. Truncated singular value decomposition (TSVD) is a common algorithm of ionospheric tomography reconstruction. However, the TSVD method usually has low inversion accuracy and reconstruction efficiency. To resolve the above problem, a truncated mapping singular value decomposition (TMSVD) algorithm is presented to improve the reconstructed accuracy and computational efficiency. To authenticate the effectiveness and the advantages of the TMSVD algorithm, a numerical test scheme is devised. Finally, ionospheric temporal–spatial variations of the selected reconstructed region are studied using the GNSS observations under different geomagnetic conditions. The reconstructed results of TMSVD can accurately reflect semiannual anomalies, diurnal variations, and geomagnetic storm effects. In contrast with the ionosonde data, it is found that the reconstructed profiles of the TMSVD method are more consistent with than those of the IRI 2016. The study suggests that TMSVD is an efficient algorithm for the tomographic reconstruction of ionospheric electron density (IED)

Expression and information hierarchical authorization of BDS reference station observation data based on states and residual

BDS reference stations typically store and transmit raw observations directly and make them available to users, which can lead to two disadvantages:first, there is no hierarchical authorization mechanism for users. Any user can solve the precise spatial, time and atmospheric datum information of the reference station through the original observation measurement, which poses a potential threat to the safety of the reference station, second, the strong correlation between the original observation measurement leads to a large amount of data, in BDS receiver observation appears network, uninterrupted, high sampling and multi-band trend, its observation data is a massive explosion, to the data storage and transmission have brought great pressure. Therefore, this paper proposes to use state and residual to express the raw observation data of BDS reference station. Compared with the common data services based on international protocols such as RINEX, Compact RINEX and RTCM, the advantage of this method is that it cannot only provide hierarchical authorization service of datum information for users, technically guarantee the security of data services, but also significantly reduce the amount of transmission data and user-side computation. At the same time, the new expression is equivalent to the original data and does not reduce the accuracy of the final calculation results. This method can be used to establish BDS observation data storage and transmission protocol with independent intellectual property rights, and provide technical support for satellite-based broadcasting services of high-precision data