| 1. |
- Becker, J., et al.
(författare)
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The high speed, high dynamic range camera AGIPD
- 2013
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Ingår i: IEEE Nuclear Science Symposium Conference Record. - : IEEE conference proceedings. - 9781479905348 ; , s. Art. no. 6829504-
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Konferensbidrag (refereegranskat)abstract
- The European X-Ray Free Electron Laser (XFEL) will provide ultra short, highly coherent X-ray pulses which will revolutionize scientific experiments in a variety of disciplines spanning physics, chemistry, materials science, and biology. One of the differences between the European XFEL and other free electron laser sources is the high pulse frequency of 4.5 MHz. The European XFEL will provide pulse trains, consisting of up to 2700 pulses separated by 220 ns (600 μs in total) followed by an idle time of 99.4 ms, resulting in a supercycle of 10 Hz. Dedicated fast 2D detectors are being developed, one of which is the Adaptive Gain Integrating Pixel Detector (AGIPD). AGIPD is based on the hybrid pixel technology. The design goals of the recently produced, radiation hard Application Specific Integrated Circuit (ASIC) with dynamic gain switching amplifiers are (for each pixel) a dynamic range of more than 10 4 12.4 keV photons in the lowest gain, single photon sensitivity in the highest gain, an analog memory capable of storing 352 images, and operation at 4.5 MHz frame rate. A vetoing scheme allows to maximize the number of useful images that are acquired by providing the possibility to overwrite any previously recorded image during the pulse train. The AGIPD will feature a pixel size of (200 μm)2 and a silicon sensor with a thickness of 500 μm. The image data is read out and digitized between pulse trains. © 2013 IEEE.
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| 2. |
- Graafsma, Heinz, et al.
(författare)
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PERCIVAL soft X-ray imager
- 2013
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Ingår i: IEEE Nuclear Science Symposium Conference Record. - : IEEE conference proceedings. - 9781479905348 ; , s. Art. no. 6829506-
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Konferensbidrag (refereegranskat)abstract
- Our goal is to provide the scientific community with a large (10cm × 10cm) pixellated detector featuring a large dynamic range (1-105 photons), good spatial resolution (27μm), good Quantum Efficiency (QE) in the low energy range (250eV-1keV), variable readout speed (up to 120 frames/s), i.e. with characteristics compatible with user needs at today's of low-energy Free Electron Lasers (FEL) and synchrotron sources. © 2013 IEEE.
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| 3. |
- Häggström, Ida, 1982-, et al.
(författare)
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Do scatter and random corrections affect the errors in kinetic parameters in dynamic PET? : a Monte Carlo study
- 2013
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Ingår i: 2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC). - : IEEE conference proceedings. - 9781479905348
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Konferensbidrag (refereegranskat)abstract
- Dynamic positron emission tomography (PET) data can be evaluated by compartmental models, yielding model specific kinetic parameters. For the parameters to be of quantitative use however, understanding and estimation of errors and uncertainties associated with them are crucial.The aim in this study was to investigate the effects of the inclusion of scattered and random counts and their respective corrections on kinetic parameter errors.The MC software GATE was used to simulate two dynamic PET scans of a phantom containing three regions; blood, tissue and a static background. The two sets of time-activity-curves (TACs) used were generated for a 2-tissue compartment model with preset parameter values (K1, k2, k3, k4 and Va). The PET data was reconstructed into 19 frames by both ordered-subset expectation maximization (OSEM) and 3D filtered back-projection with reprojection (3DFBPRP) with normalization and additional corrections (A=attenuation, R=random, S=scatter, C=correction): True counts (AC), true+random counts (ARC), true+scattered counts (ASC) and total counts (ARSC).The results show that parameter estimates from true counts (AC), true+random counts (ARC), true+scattered counts (ASC) and total counts (ARSC) were not significantly different, with the exception of Va where the bias increased with added corrections. Thus, the inclusion of and correction for scattered and random counts did not affect the bias in parameter estimates K1, k2, k3, k4 and Ki. Uncorrected total counts (only AC) resulted in biases of hundreds or even thousands of percent, emphasizing the need for proper corrections. Reconstructions with 3DFBPRP resulted in overall 20-40% less biased estimates compared to OSEM.
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| 4. |
- Kanaki, K., et al.
(författare)
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An alternative small angle neutron scattering detector
- 2013
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Ingår i: IEEE Nuclear Science Symposium Conference Record. - : IEEE conference proceedings. - 9781479905348 ; , s. Art. no. 6829478-
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Konferensbidrag (refereegranskat)abstract
- An alternative detector design for Small Angle Neutron Scattering (SANS) applications is currently under development at the European Spallation Source (ESS). Given the unavailability and high price of 3He, this detector design utilizes gaseous detectors with 10B as neutron converter and is ideally suited for a SANS instrument at the ESS. The novel aspects of the geometry, exploiting the properties of the converting material, in combination with the performance of the detector are addressed by means of analytical calculations, as well as detailed Monte Carlo simulations using a customized version of Geant4. Last but not least, the progress on the conceptual prototype design is presented. © 2013 IEEE.
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| 5. |
- Kanaki, K., et al.
(författare)
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Statistical energy determination in neutron detector systems for neutron scattering science
- 2013
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Ingår i: IEEE Nuclear Science Symposium Conference Record. - : IEEE conference proceedings. - 9781479905348 ; , s. Art. no. 6829644-
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Konferensbidrag (refereegranskat)abstract
- The energy determination of thermal and cold neutrons could revolutionize the field of neutron scattering science and transform the instrument design for future facilities. This contribution evaluates the feasibility and potential of a statistical determination of the neutron energy in the new generation of neutron detectors. In particular, the novel technology of multi-layer 10B thin film detectors present a unique opportunity of exploiting this possibility by using the various neutron penetration depths to extract energy information. A statistical mathematical model for doing so is being developed. To this end, measurements of absorption profiles on boron carbide have been performed at the Institutt for Energiteknikk, Norway and the Helmholtz Zentrum Berlin, Germany. The results of the data analysis allow for a preliminary estimate on the feasibility and the potential of this method. © 2013 IEEE.
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| 6. |
- Kole, Merlin, 1986-, et al.
(författare)
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A balloon-borne measurement of high latitude atmospheric neutrons using a licaf neutron detector
- 2013
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Ingår i: 2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC). - : IEEE conference proceedings. - 9781479905348 ; , s. 6829591-
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Konferensbidrag (refereegranskat)abstract
- PoGOLino is a scintillator-based neutron detector. Its main purpose is to provide data on the neutron flux in the upper stratosphere at high latitudes at thermal and nonthermal energies for the PoGOLite instrument. PoGOLite is a balloon borne hard X-ray polarimeter for which the main source of background stems from high energy neutrons. No measurements of the neutron environment for the planned flight latitude and altitude exist. Furthermore this neutron environment changes with altitude, latitude and solar activity, three variables that will vary throughout the PoGOLite flight. PoGOLino was developed to study the neutron environment and the influences from these three variables upon it. PoGOLino consists of two Europium doped Lithium Calcium Aluminium Fluoride (Eu:LiCAF) scintillators, each of which is sandwiched between 2 Bismuth Germanium Oxide (BGO) scintillating crystals, which serve to veto signals produced by gamma-rays and charged particles. This allows the neutron flux to be measured even in high radiation environments. Measurements of neutrons in two separate energy bands are achieved by placing one LiCAF detector inside a moderating polyethylene shield while the second detector remains unshielded. The PoGOLino instrument was launched on March 20th 2013 from the Esrange Space Center in Northern Sweden to an altitude of 30.9 km. A description of the detector design and read-out system is presented. A detailed set of simulations of the atmospheric neutron environment performed using both PLANETOCOSMICS and Geant4 will also be described. The comparison of the neutron flux measured during flight to predictions based on these simulations will be presented and the consequences for the PoGOLite background will be discussed.
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| 7. |
- Larsson, Anne, et al.
(författare)
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Optimal contrast as a function of noise for Butterworth filtering of 111 In-pentetreotide SPECT when using model-based compensation
- 2013
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Ingår i: 2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC). - 9781479905348
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Konferensbidrag (refereegranskat)abstract
- In 111 In-pentetreotide SPECT, it can be difficult to detect small tumors because of low spatial resolution and high noise levels. For an efficient cancer treatment, it is however important to detect the tumors at an early stage. The aim of this study was to perform optimization of Butterworth post-filtering of In-111-pentetreotide SPECT, with regard to small tumor detection in the liver. All images were reconstructed with model-based OSEM reconstruction. Two collimators are evaluated, the extended low-energy general-purpose (ELEGP) and the medium-energy general-purpose (MEGP) collimator. The raw-data projection images are produced using Monte Carlo simulations of an anthropomorphic phantom with realistic In-111-pentetreotide uptake, including seven spherical tumors in the liver. Evaluation was performed using tumor contrast as a function of background noise. According to the results, the detection of the smallest tumors is facilitated by not applying a filter. For somewhat larger tumors, a Butterworth filter of critical frequencies of 0.5-0.6 cm(-1) and an order of 10-12 is more appropriate. ELEGP proved to be better than MEGP for small tumor detection. The study is a continuation of a previous project where collimator choice, acquisition time, number of projection angles and OSEM settings were studied for the same geometry.
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| 8. |
- Wallstén, Elin, et al.
(författare)
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The Influence of Time Sampling on Parameters in the Logan Plot
- 2013
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Ingår i: 2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC). - 9781479905348
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Konferensbidrag (refereegranskat)abstract
- The Logan plot is a graphical method for reversible tracer bindings. The bias and uncertainties of this method have previously been analyzed with respect to noise, but little is known about the direct effects from varying the time sampling scheme. This study aims to investigate the effect of time sampling on the binding potential from the reference Logan plot. Image data from seven healthy subjects imaged with [11C]raclopride was reconstructed into six dynamic series of equal length time frames with frame times between 15 s and 480 s. Images were reconstructed using both filtered back projection (FBP) and a resolution enhanced ordered subset expectation maximization (OSEM) algorithm, SharpIR. For each sampling scheme, the nondisplaceable binding potential (BPND) parameter was calculated from the reference Logan plot with cerebellum as a reference region. The variation in BPND was analyzed as percentage deviations from the BPND for the 480 s scheme. R-2 of the linear fit was also analyzed. Comparison between all sampling schemes showed that the largest deviation in BPND was 7.4% between the 15 s sampling scheme and the 480 s sampling scheme reconstructed with SharpIR. The corresponding deviation for FBP images was 1.6%. R-2 was highest for long time frames, but all R-2 values were above 0.997 in this study.
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| 9. |
- Åkerstedt, Henrik, 1987-, et al.
(författare)
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Radiation tolerance and mitigation strategies for FPGA:s in the ATLAS TileCal Demonstrator
- 2013
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Ingår i: 2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC). - Piscataway : IEEE. - 9781479905348 - 9781479905324 ; , s. 2978-2981
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Konferensbidrag (refereegranskat)abstract
- During 2014, upgraded-demonstrator electronics will be installed in a Tile calorimeter drawer to obtain long term experience with the redundant electronics proposed for a full upgrade scheduled for 2022.The new, FPGA-based system uses dense programmable logic, which must be proven to be sufficiently radiation tolerant. It must also be protected against radiation induced single event upsets that can corrupt memory and logic Radiation induced errors need to be detected and compensated for in time to minimize data loss, and also to avoid permanent damage. Strategies for detecting and correcting radiation induced errors in the Kintex-7 FPGAs on the Demonstrator electronics are evaluated and discussed.
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