Statistical event reconstruction techniques can give better results for gamma cameras than the traditional centroid method. However, implementation of such techniques requires detailed knowledge of the photomultiplier tube light-response functions. Here we describe an iterative method which allows one to obtain the response functions from flood irradiation data without imposing strict requirements on the spatial uniformity of the event distribution. A successful application of the method for medical gamma cameras is demonstrated using both simulated and experimental data. An implementation of the iterative reconstruction technique capable of operating in real time is presented. We show that this technique can also be used for monitoring photomultiplier gain variations.

ANTS2 is a simulation and data processing package developed for position sensitive detectors with Anger camera type readout. The simulation module of ANTS2 is based on ROOT package from CERN, which is used to store the detector geometry and to perform 3D navigation. The module is capable of simulating particle sources, performing particle tracking, generating photons of primary and secondary scintillation, tracing optical photons and generating photosensor signals. The reconstruction module features several position reconstruction methods based on the statistical reconstruction algorithms (including GPU-based implementations), artificial neural networks and k-NN searches. The module can process simulated as well as imported experimental data containing photosensor signals. A custom library for B-spline parameterization of spatial response of photosensors is implemented which can be used to calculate and parameterize the spatial response of a detector. The package includes a graphical user interface with an extensive set of configuration, visualization and analysis tools. ANTS2 is being developed with the focus on the iterative (adaptive) reconstruction of the detector response using flood field irradiation data. The package is implemented in C++ programming language and it is a multiplatform, open source project.

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Nanocomposite catalyst containing palladium-nickel boride-silica and reduced graphene oxide (Pd@Ni x B-SiO 2 /RGO, abbreviated as Pd@NSG) was successfully fabricated and discussed its enhanced hydrogen spillover mechanism and high catalytic performance towards reduction of 4-nitrophenol (4-NP) 10 to 4-aminophenol (4-AP). The structure, composition and morphology of Pd@NSG nanocomposite were characterized by various techniques. The H 2 adsorption experiment directly reveals the spillover effect on Pd@NSG nanocomposite and enhanced H 2 uptake capacity (0.7 wt. %) compared to SiO 2 /RGO (0.05 wt. %) under 50 bar pressure at RT. 4-NP reduction reaction shows remarkably high activity (120 s) of Pd@NSG compared to Ni x B-SiO 2 /RGO (7200 s) with excellent stability up to 5 cycles. Both the 15 experiments showed, the facile H 2 dissociation on Pd (active sites) activator and subsequent transportation of hydrogen atom on receptor sites (Ni x B-SiO 2 /RGO and 4-NP, respectively). 30 nanocomposite with high performance. 11

A framework for parameterization of the light response functions (LRFs) in a scintillation camera is presented. It is based on approximation of the measured or simulated photosensor response with weighted sums of uniform cubic B-splines or their tensor products. The LRFs represented in this way are smooth, computationally inexpensive to evaluate and require much less computer memory than non-parametric alternatives. The parameters are found in a straightforward way by the linear least squares method. Several techniques that allow to reduce the storage and processing power requirements were developed. A software library for fitting simulated and measured light response with spline functions was developed and integrated into an open source software package ANTS2 designed for simulation and data processing for Anger camera type detectors.