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Characterisation of High Purity Germanium (HPGe) detectors in order to predict the response of the detector to different gamma ray interactions is one of the current goals in the Nuclear physics community. This purpose includes a theoretical study of the detector from the simulation point of view and an experimental stage to validate the goodness of the considerations performed. In this work, the...
Traditional gamma camera collimators have been based on a standard parallel design, usually with parallel holes. The collimator determines the resolution of the camera, but is also the determining factor of the number of counts detected. The uncertainty about the origin of the detected photons is modelled by a Point Spread Function (PSF), which, in literature, is normally assumed to be a Gaussian...
Today's 3rd generation CT scanners have one or two X-ray tubes, with one focal spot or “source” per vacuum chamber or “tube”. Our first multi-source inverse geometry CT prototype has eight X-ray sources. We have demonstrated multisource imaging with an 8-spot X-ray tube on a stationary gantry and a rotating phantom. We present an update on the development of the gantry-based multi-source CT scanner:...
One of the main issues regarding a gaseous detector is the gas flow inside the detector itself. A bad gas flow can affect irreversibly the chamber performance. On the other hand optimizing gas circulation inside the detector could allow a safe and reliable operation even with less gas consumption while at the same time maintaining high performance. Simulations and comparison between several different...
A simulation tool has been developed using the Geant4 toolkit to simulate a phoswich single channel beta gamma coincidence detection system consisting of three layers of different scintillation materials: BC400, CsI and BGO. Monte Carlo simulation techniques are powerful tools for investigating the performance of radiation detectors. Geant4 is a simulation toolkit that can realistically model optical...
The CMS collaboration has developed a fast Monte Carlo simulation of the CMS detector with event production rates ~100 times faster than the GEANT4-based simulation, with comparable accuracy for most of the high level observables to be used in the physics analyses. We discuss basic technical principles of the CMS Fast Simulation and their implementation in the different components of the detector:...
An Application Specific Integrated Circuit (ASIC) has been developed at the Rutherford Appleton Laboratory (RAL) to study the small pixel effect in spectroscopic CdTe and CdZnTe detectors. The PIXIE ASIC consists of four arrays of 3×3 channels flip chip bonded directly to the detector pixels. The active circuitry of each channel is a charge sensitive preamplifier and an output buffer which is multiplexed...
The SuperB experiment needs large samples of Monte-Carlo simulated events in order to finalize the detector design and to estimate the data analysis performances. This work describes the system we developed to manage the production of the required simulated events in a fully distributed environment. The distributed infrastructure includes several sites in Europe and North America and is based on Grid...
The ATLAS experiment, operational at the new LHC collider, is fully simulated using a Geant 4-based simulation program within the ATLAS Athena framework. This simulation software is used for large-scale production of events on the LHC Computing Grid as well as for smaller-scale studies. Simulation of ATLAS requires many components, from the generators that simulate particle collisions to packages...
Circular cone-beam CT is one of the most popular configurations in both medical and industrial applications. The FDK algorithm is the most popular method for circular cone-beam CT. However, with increasing cone angle the cone-beam artifacts associated with the FDK algorithm deteriorate because the circular trajectory does not satisfy the data sufficiency condition. Along with an experimental evaluation...
Circular cone-beam computed tomography (CBCT) with a tangentially offset flat-panel X-ray detector offers a large CT field-of-view (FoV) with a relatively small detector. It is used in practice, e.g., for target imaging in image-guided radiotherapy or for localization and attenuation correction in SPECT/CT imaging. The X-ray projections, acquired on a circular source trajectory, each cover roughly...
ICx Radiation has developed a novel method to determine the direction of radiation with a device containing only two detectors by comparing and analyzing the paired-energy distributions of coincident events. The method does not require complex image reconstruction but rather extracts the directionality from the means and skewness of the two coincidence spectra. All energy data contribute to the energy...
Modeling of gamma spectra is required in various fields. The growth of usage of spectrometric border monitoring methods to combat illicit trafficking of nuclear and other radioactive materials enhances the need for such techniques. With the development of the Gamma Spectrum Generator within the Nucleonica web-portal (www.nucleonica.net) a new ansatz is made, which allows authorized experts to perform...
The calorimeter of KLOE at INFN-LNF is a high-sampling, lead/scintillating-fiber calorimeter primarily designed to detect photons with very high efficiency. During a KLOE study of kaon interactions in the apparatus walls, hints of a high efficiency for low energy neutrons (<; 20MeV) were observed and confirmed by the experiment simulation. A more systematic study, involving exposing the prototype...
This paper presents the implementation of the Point Detector Scorer in the Monte Carlo simulation code GAMOS/Geant4. The Point Detector Scorer (PDS) is equivalent to F5 tally implemented in MCNP/X. There has been a systematic comparison between the PDS and the F5 tally for several isotopes and mixed materials, here we present the results for a single isotope 208Pb and for concrete, two important materials...
We consider the problem of finding the least-squares solution to a system of linear equations where the unknown vector has integer entries (or, more precisely, has entries belonging to a subset of the integers), yet where the coefficient matrix and given vector are comprised of real numbers. Geometrically, this problem is equivalent to finding the closest lattice point to a given point and is known...
This paper introduces a topology based affine invariant descriptor for maximally stable extremal regions (MSERs). The popular SIFT descriptor computes the texture information on a grey-scale patch. Instead our descriptor use only the topology and geometric information among MSERs so that features can be rapidly matched regardless of the texture in the image patch. Based on the ellipses fitting for...
Improper dose control in X-ray cardio-vascular systems leads to a reduced Signal-to-Noise Ratio (SNR) in regions of interest of the X-ray image. We aim at reducing the influence of direct radiation, entering a measuring field for X-ray dose control in a Flat Detector which gives too bright areas (highlights) in the image. It is our desire to use a norm-like signal size that represents a minimal dose...
We describe the design, optimization and optical tests of Microwave Kinetic Inductance Detectors for mm and sub-mm wavelengths. Our detectors are based on a novel resonator design, and can be easily tuned to suit different experimental needs by choosing the correct geometry.
We propose a new algorithm for detecting multiple object categories that exploits the fact that different categories may share common features but with different geometric distributions. This yields an efficient detector which, in contrast to existing approaches, considerably reduces the computation cost at runtime, where the feature computation step is traditionally the most expensive. More specifically,...
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