المؤلفون: Šagátová Andrea, Fülöp Marko, Novák Andrej, Vrban Branislav, Lüley Jakub, Čerba Štefan, Benkovský Ivan, Zaťko Bohumír

المصدر: Nukleonika, Vol 69, Iss 2, Pp 135-140 (2024)

مصطلحات موضوعية: hybrid pixel detector, neutron conversion, neutron radiography, timepix2, Science

الوصف: The Timepix2-based hybrid-pixel detector with a 500 μm thick silicon sensor was employed for fast-neutrons registration to be applied in neutron radiography of metallic printed circuit heat exchanger (PCHE). Two energies of neutrons were experimentally tested. The detection of 3.55 MeV neutrons from the deuteron–deuteron (DD) reaction was compared to 15.7 MeV neutrons from the deuteron–tritium (DT) neutron generator. In order to distinguish the signal induced by the registered neutrons from the accelerator background, filtration of the recorded particle spectral tracks was applied. The benefit of applying hydrogen-based converter layer for 3.55 MeV neutrons was observable. On the other hand, in the case of 15.7 MeV neutrons, the direct registration by interaction with the sensor Si significantly dominates the conversion.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1508-5791Test

الوصول الحر: https://doaj.org/article/e55bd34d1c2d4eeca8590e9d875575bcTest

المؤلفون: Calderón, Yonatán

المساهمون: University/Department: Universitat Autònoma de Barcelona. Departament de Física

مرشدي الرسالة: Chmeissani, Mokhtar, Kolstein, Machiel, Casado, Pilar

المصدر: TDX (Tesis Doctorals en Xarxa)

مصطلحات موضوعية: Comton camera, Pixel detector, Qcdt detector, Ciències Experimentals

الوصف: Desde el descubrimiento de los rayos X en 1895 y su primera aplicación médica un año después, se han desarrollado diferentes técnicas de imagen médica. La tomografía por emisión es una rama de las imágenes médicas que permite a los médicos realizar un seguimiento de los procesos fisiológicos en el paciente. Un compuesto radiactivo llamado radiotrazador se inyecta en el cuerpo del paciente. La molécula radiotrazador se elige para cumplir una tarea específica en el organismo que permite el seguimiento de un proceso fisiológico concreto. Los dos principales de técnicas de tomografía por emisión son PET y SPECT. En PET (Tomografía por Emisión de Positrones) el radiotrazador inyectado es un emisor de positrones. El positrón emitido se aniquila con un electrón produciendo un par de fotones gamma emitidos “back -to-back”. El escáner PET (por lo general de forma cilíndrica) detecta estos pares de fotones y reconstruye una imagen de la concentración del radiotrazador en el organismo. En SPECT (Tomografía Computarizada por Emisión Simple de Fotones) un solo fotón gammas es emitido en cada desintegración radiactiva del compuesto. El sistema de SPECT consiste en (al menos) una cámara gamma. Una cámara gamma está compuesta por un colimador mecánico y un fotodetector capaz de registrar la posición de la interacción. El colimador mecánico esta compuesto por un material denso con aperturas que sólo permite el paso de los fotones procedentes de una dirección particular. Los fotones colimados son detectados por el detector obteniendo una proyección del radiotrazador en el volumen del cuerpo del paciente. A partir de estas proyecciones se obtiene una imagen tomografía de la concentración del radiotrazador- SPECT es la técnica de tomografía de emisión más ampliamente utilizado debido a la gran variedad de radiotrazadores disponibles, y el bajo coste en comparación con PET. Sin embargo, SPECT tiene limitaciones intrínsecas debido a la colimación mecánica: baja eficiencia ya que sólo una fracción de los fotones gamma puede pasar a través del colimador, una relación proporcional inversa entre la eficiencia y la resolución de la imagen ( A mayor tamaño de las aperturas del colimador mayor será la eficiencia pero la resolución de la imagen empeorara) , y la cámara debe girar aumentando el tiempo de exposición . El concepto de cámara Compton fue concebido con el fin de superar estas limitaciones. Una cámara de Compton consta de dos detectores, llamados “scatterer” y “absorber”, trabajando en coincidencia. En un evento de coincidencia el fotón gamma (emitido por el radiotrazador) alcanza el “scatterer” y cambia de dirección como consecuencia de una interacción Compton. La gamma dispersada alcanza el “absorber" donde es absorbida en una interacción fotoeléctrica. Con la posición de ambas interacciones y las correspondientes energías, se puede reconstruir la superficie de un cono que contiene el punto desde donde el fotón gamma fue emitido. Con los conos reconstruidos a partir de varias coincidencias, es posible reconstruir una imagen de la actividad en el cuerpo del paciente. La cámara Compton tiene el potencial de superar todas las limitaciones intrínsecas de los SPECT ya que: cada gamma tiene una probabilidad de ser dispersado y producir una coincidencia, la resolución de la imagen no está vinculada a la eficiencia, y es posible obtener imágenes tridimensionales sin mover la cámara. Sin embargo, la complejidad de la reconstrucción de la imagen y los límites en la tecnología de detectores, han impedido que el concepto de cámara Compton se convertirse en un sistema de imagen médica viable. El proyecto VIP (“Voxel Imaging PET”) propone un diseño de detector de estado sólido (CdTe) con tecnología pixel para superar las limitaciones de los detectores basados en cristales de centelleo utilizados en PET. VIP cuenta con un diseño modular en el que el elemento básico es el modulo de detección. El módulo contiene los detectores de estado sólido que están segmentados en “voxels” de tamaño milimétrico. Gracias a un chip de lectura desarrollado en el proyecto, cada uno de los “voxels” del detector constituye un canal independiente para la medición de la energía, posición, y el tiempo de llegada de los fotones gamma detectados. Los módulos son apilados con el fin de formar los sectores de PET. Poner varios de estos sectores juntos, permite construir un anillo PET. Aunque el módulo VIP ha sido diseñado para el PET, la flexibilidad del diseño del módulo permite explorar otras posibles aplicaciones, como PEM (Mamografía por Emisión de positrones) y la cámara de Compton. En esta tesis se evaluará una cámara de Compton basado en el concepto detector VIP. Los detectores “scatterer” y “absorber” están compuestos de módulos de detección especial diseñados. Los módulos son apilados para crear los detectores. En el “scatterer” se utiliza Silicio como material activo a fin de maximizar la probabilidad de interacción Compton de los fotones. En el “absorber”, CdTe se utiliza como material activo con el fin de detener los fotones gamma que salen del “scatterer”. La excelente resolución en la energía de los detectores de estado sólido combinado con el tamaño milimétrico de los “voxels”, permiten obtener una alta precisión en la reconstrucción de los conos Compton que no se puede lograr con cristales de centelleo. En esta tesis vamos a utilizar simulaciones de Monte Carlo para evaluar y optimizar el diseño de la cámara Compton. Se utilizarán dos algoritmos de reconstrucción de imagen diferentes. La simulación nos permitirá obtener los parámetros geométricos óptimos, así como el rendimiento esperado de la cámara de Compton en términos de eficiencia en la detección y de resolución de la imagen. Se ha evaluado también un prototipo con menor campo de visión.

الوصف (مترجم): Since the discovery of the X-rays in 1895 and their first medical application one year later, many different medical imaging techniques have been developed. Emission tomography is a branch of medical imaging that allows the doctors to track physiological processes in the patient. A radioactive compound called radiotracer is injected in the body of the patient. The radiotracer molecule is chosen to fulfill an specific task in the organism allowing to track a concrete physiological process. The two main emission tomography techniques are PET and SPECT. In PET (Positron Emission Tomography) the injected radiotracer is a positron emitter. The emitted positron annihilates with an electron producing a pair of back-to-back gamma photons. The PET scanner (usually having a cylindrical shape) detects these photons pairs and reconstructs an image of the radiotracer concentration. In SPECT (Single Photon Emission Computerized Tomography) a single gamma photon is emitted in each radioactive decay of the radiotracer compound. The SPECT system consists of (at least) one gamma camera. A gamma camera is composed by a mechanical collimator and a position sensitive photodetector. The mechanical collimator consists of a thick material with holes that only allow the passing of photons coming from a particular direction. The collimated photons are detected by the photodetector obtaining a projection of the radiotracer in the volume of the patient body. A three dimensional image of the radiotracer concentration in the patient body is obtained from the projections obtained in several directions. SPECT is the most widely used emission tomography technique because of the large variety of available radiotracers, and the relative low cost when compared with PET. However, SPECT has intrinsic limitations due to the mechanical collimation: low efficiency as only a fraction of the gamma photons can pass through the collimator, an inverse proportional relationship between the efficiency and the image resolution (the bigger the collimator holes the higher the efficiency but the lower the image resolution), and the camera must be rotated increasing exposure time. The concept of Compton camera has been proposed in order to overcome those limitations. A Compton camera consists of two detectors, called scatterer and absorber, working in coincidence. In a coincidence event the gamma photon (emitted by the radiotracer) reaches the scatterer and undergoes a Compton interaction, scattering into a certain angle. The scattered gamma reaches the absorber where it undergoes a photoelectric interaction and is absorbed. Using the positions of both interactions and the corresponding deposited energies, one can reconstruct a cone surface which contains the emission point of the gamma photon. With the cones reconstructed from several coincidences, an image of the activity in the patient body can be obtained. The Compton camera has the potential to overcome all the intrinsic limitations of SPECT as: each gamma has a probability to be scattered and produce a coincidence event, the image resolution is not tied to the efficiency, and it is possible to obtain three dimensional images without moving the camera. However, the complexity of the image reconstruction and the limits in the detector technology has prevented the Compton camera concept to become a viable medical imaging system. The VIP (Voxel Imaging PET) project proposes a novel detector design based on pixelated solid state (CdTe) technology to overcome the limitations of scintillator detectors used in PET. VIP features a modular design in which the basic element is the detector module unit. The module contains the solid state detectors which are segmented in millimeter size voxels. Thanks to a dedicated read-out chip developed within the project, each one of the voxels is an independent channel for the measurement of energy, position, and time of arrival of the detected gamma photons. The module detectors are stacked in order to form PET sectors. Putting several of these sectors together leads to a seamless PET ring. Although the VIP module has been designed for PET, the flexibility of the module design allows to explore other possible applications like PEM (Positron Emission Mammography) and Compton camera. In this thesis we will evaluate a Compton camera based on the VIP detector concept. The scattering and the absorber detectors will be made from the stacking of specially designed module units. Silicon will be used as detector material in the scatterer in order to maximize the Compton interaction probability for the incoming gamma photons. In the absorber, CdTe will be used as detector material in order to stop the gamma photons emerging from the scatterer. The excellent energy resolution of the solid state detectors combined with the millimeter size of the detector voxels, result in a high accuracy in the reconstruction of the Compton cones that cannot be achieved with scintillator crystals. In this thesis we will use Monte Carlo simulations in order to evaluate and model the proposed Compton camera. Two different image reconstruction algorithms will be used. The simulation will allow us to obtain the optimal geometrical parameters as well as the expected performance of the Compton camera in terms of detection efficiency and image resolution. A smaller FOV (Field-Of-View) prototype will be also evaluated.

وصف الملف: application/pdf

الوصول الحر: http://hdl.handle.net/10803/283441Test

المؤلفون: Daniel Prelipcean, Giuseppe Lerner, Ivan Slipukhin, David Lucsanyi, Hampus Sandberg, James Storey, Pedro Martin-Holgado, Amor Romero-Maestre, Yolanda Morilla García, Rubén García Alía

المصدر: Applied Sciences, Vol 14, Iss 2, p 624 (2024)

مصطلحات موضوعية: Timepix3, radiation monitor, Radiation to Electronics (R2E), FLUKA, silicon pixel detector, saturation effect, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, QD1-999

الوصف: A Timepix3 detector with a 300 μ m silicon sensor has been studied as a novel radiation monitor for the mixed radiation field at the Large Hadron Collider at CERN. This work describes a test campaign carried out at Centro Nacional de Aceleradores with quasi-mono energetic protons (alphas) from 0.6 (1) to 5 (5.6) MeV, where orthogonal irradiations are used to obtain an energy calibration, and a low-energy angular scan to estimate the front dead layer thickness of the sensor. The detector is operated in hole collection mode and at a partial bias of 250 μ m at 50 V , which increases the charge sharing among pixels to mitigate the signal saturation at high energy depositions. The data, supported by FLUKA Monte Carlo simulations of energy losses in the sensor, show that the Timepix3 monitor operates in a linear regime up to energy depositions of around 600 k e V per pixel and 2 M e V per cluster. As a result, the detector has been found to be suitable for measuring charged particle fluxes in the LHC mixed radiation field within the linear calibration regime, with the partial exception of inelastic nuclear reaction hits (mostly from neutrons).

العلاقة: https://www.mdpi.com/2076-3417/14/2/624Test; https://doaj.org/toc/2076-3417Test; https://doaj.org/article/9a85dec2a5034f3198af660c606f6952Test

الإتاحة: https://doi.org/10.3390/app14020624Test
https://doaj.org/article/9a85dec2a5034f3198af660c606f6952Test

المؤلفون: Tilman Donath, Dubravka Šišak Jung, Max Burian, Valeria Radicci, Pietro Zambon, Andrew N. Fitch, Catherine Dejoie, Bingbing Zhang, Marie Ruat, Michael Hanfland, Cameron M. Kewish, Grant A. van Riessen, Denys Naumenko, Heinz Amenitsch, Gleb Bourenkov, Gerard Bricogne, Ashwin Chari, Clemens Schulze-Briese

المصدر: Journal of Synchrotron Radiation, Vol 30, Iss 4, Pp 723-738 (2023)

مصطلحات موضوعية: hybrid photon counting, pixel detector, silicon, cadmium telluride, count rate, quantum efficiency, eiger2, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798, Crystallography, QD901-999

الوصف: The ability to utilize a hybrid-photon-counting detector to its full potential can significantly influence data quality, data collection speed, as well as development of elaborate data acquisition schemes. This paper facilitates the optimal use of EIGER2 detectors by providing theory and practical advice on (i) the relation between detector design, technical specifications and operating modes, (ii) the use of corrections and calibrations, and (iii) new acquisition features: a double-gating mode, 8-bit readout mode for increasing temporal resolution, and lines region-of-interest readout mode for frame rates up to 98 kHz. Examples of the implementation and application of EIGER2 at several synchrotron sources (ESRF, PETRA III/DESY, ELETTRA, AS/ANSTO) are presented: high accuracy of high-throughput data in serial crystallography using hard X-rays; suppressing higher harmonics of undulator radiation, improving peak shapes, increasing data collection speed in powder X-ray diffraction; faster ptychography scans; and cleaner and faster pump-and-probe experiments.

وصف الملف: electronic resource

العلاقة: http://scripts.iucr.org/cgi-bin/paper?S160057752300454XTest; https://doaj.org/toc/1600-5775Test

الوصول الحر: https://doaj.org/article/d99ef41a410b4f9788dc60d55d1e0e1aTest

المؤلفون: Yingdong Song, Haibo Yang, Yuezhao Zhang, Jianwei Liao, Yanhao Jia, Peng Ma, Yufeng Hou, Xiangming Sun, Hulin Wang, Haisheng Song, Chengxin Zhao

المصدر: Sensors, Vol 24, Iss 8, p 2387 (2024)

مصطلحات موضوعية: beam monitor, data acquisition, pixel detector, readout electronics, Chemical technology, TP1-1185

الوصف: To monitor the position and profile of therapeutic carbon beams in real-time, in this paper, we proposed a system called HiBeam-T. The HiBeam-T is a time projection chamber (TPC) with forty Topmetal-II- CMOS pixel sensors as its readout. Each Topmetal-II- has 72 × 72 pixels with the size of 83 μm × 83 μm. The detector consists of the charge drift region and the charge collection area. The readout electronics comprise three Readout Control Modules and one Clock Synchronization Module. This Hibeam-T has a sensitive area of 20 × 20 cm and can acquire the center of the incident beams. The test with a continuous 80.55 MeV/u 12C6+ beam shows that the measurement resolution to the beam center could reach 6.45 μm for unsaturated beam projections.

وصف الملف: electronic resource

العلاقة: https://www.mdpi.com/1424-8220/24/8/2387Test; https://doaj.org/toc/1424-8220Test

الوصول الحر: https://doaj.org/article/3fd3e0869f544122aedcf178e1dc57b5Test

المؤلفون: Sandberg, Hampus

المساهمون: Owen, Hywel, Bertsche, William

مصطلحات موضوعية: 539.7, Timepix3, Hybrid Pixel Detector, BGI, CERN, Beam Instrumentation, Beam Profile Monitor, IPM

الوصف: Beam profile and emittance monitoring is essential to understand the dynamic behaviour of the ensemble of particles in an accelerator beam. A non-invasive measurement of the beam profile ensures reliable measurements. One such device is the beam gas Ionisation Profile Monitor (IPM), which relies on detecting the ionisation products from the interaction between residual gas molecules in the vacuum of the accelerator and the beam particles. Traditional detectors in IPMs have limited the instruments reliability and performance. A novel approach using Timepix3 pixel detectors is explored in this thesis project which enables direct detection of ionisation electrons with a precise time resolution. A radiation hard readout system was developed to allow the maximum detection performance of the pixel detectors and beam measurements were recorded during 2018. A beam profile reconstruction method was developed that takes advantage of the information recorded by the Timepix3 detectors to identify and only select events that are associated with ionisation electrons. From these events, a beam profile was reconstructed and the beam size calculated by fitting a Gaussian model to the beam profile data or by calculating the RMS beam size directly. During 2018 a prototype IPM with pixel detectors was installed in the Proton Synchrotron at CERN. Beam profile measurements recorded with this instrument demonstrated the ability to measure the beam profile continuously throughout the beam cycle in the accelerator. Expected beam dynamics effects such as adiabatic damping and oscillations during transition crossing were observed with the instrument. The time resolution of the pixel detectors enabled bunch-by-bunch measurements of the beam profile by integrating the recorded events separately for each bunch over multiple turns.

الوصول الحر: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.823304Test

المؤلفون: Levasseur, Swann

مصطلحات موضوعية: Beam Gas Ionisation Profile Monitor, Ionisation Profile Monitor, CERN Proton Synchrotron, Beam Instrumentation, Timepix3, Hybrid Pixel Detector

الوصف: The ability to rapidly identify the source of emittance blow-up in the CERN Proton Synchrotron (PS) is crucial to ensure the good operation of the Large Hadron Collider (LHC) and its successor the High Luminosity LHC (HL-LHC). Such ability requires to continuously and non-destructively measure the beam size. However, the beam transverse diagnostics in the PS are currently performed by Beam Wire Scanners (BWS) and Secondary Emission Monitor (SEM) grids. Both of these systems provide high-quality measurements of the beam transverse size. Nonetheless, the destructive nature of their measurement method limits their use to single-shot measurements during the beam commissioning. For this reason, the installation of a new Beam Gas Ionisation (BGI) profile monitor was proposed for the PS. The new PS-BGI infers the beam profile from the transverse distribution of electrons created by the ionisation of rest gas molecules by the high energy beam particles. The distribution is measured by accelerating the electrons onto an imaging detector based on Timepix3 Hybrid Pixel Detector (HPD). This measurement method allows for continuous, non-destructive beam size measurement. Moreover, the extreme sensitivity of Timepix3 HPDs allows foregoing the use of a gas injection system, while permitting to record the beam size at several kilo-Hertz. This thesis covers the development of this new PS-BGI, from early concept and simulation to the installation and commissioning of a prototype in the PS. This prototype demonstrated the first successful use of Hybrid Pixel Detectors (HPD) in the primary vacuum of an accelerator at CERN. The performances of the prototype were characterised and the first continuous beam profile measurements of the LHC-type beam in the PS were recorded.

الوصول الحر: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.855338Test

المؤلفون: G.S. Ahmadov

المصدر: Eurasian Journal of Physics and Functional Materials, Vol 6, Iss 3, Pp 174-179 (2022)

مصطلحات موضوعية: ternary fission, ∆e - e method, timepix pixel detector, ∆e detector, silicon detector, Physics, QC1-999

الوصف: This paper presents the results of ternary light charged particles from 252 Cf spontenous fission source. The method ∆E - E was applied to identify the particle by a position sensitive ∆E - E telescope.The specific energy loss ( ∆E ) was measured using the transmission type ∆E detector (thicknesses of 150 μm ) ordered from the company Micron Semiconductors, while the residual energy (E) was measured by a Timepix detector with thicknesses of 600 μm . It was possible to measure partial-energy spectra of the various ternary particle types due to the thicknesses of Al foil (31 μm ) and ∆E detector (150 μm ) placed before E detector. The energy spectrum of protons was qualitatively different from the spectra of the other particles since protons from Al(n,p) and Si (n,p) reactions could contribute to the spectra. Ternary fission;

وصف الملف: electronic resource

العلاقة: https://www.ephys.kz/jour/article/view/321/193Test; https://doaj.org/toc/2522-9869Test; https://doaj.org/toc/2616-8537Test

الوصول الحر: https://doaj.org/article/d281225828104a1c9df3be8dac54f58fTest

المؤلفون: López Morillo, Enrique, Luján Martínez, Clara Isabel, Hinojo Montero, José María, Márquez Lasso, Fernando J., Muñoz Chavero, Fernando, Palomo Pinto, Rogelio

المساهمون: Universidad de Sevilla. Departamento de Ingeniería Electrónica, Universidad de Sevilla. TIC192: Ingeniería Electrónica, MCIN/AEI/ 10.13039/501100011033. Proyecto PID2019-107258RB-C31

مصطلحات موضوعية: depleted monolithic active pixel sensors (DMAPSs), timing, time walk, pixel detector, Large Hadron Collider (LHC), low power, area efficiency

الوصف: Depleted Monolithic Active Pixel Sensors (DMAPSs) are foreseen as an interesting choice for future high-energy physics experiments, mainly because of the reduced fabrication costs. However, they generally offer limited time resolution due to the stringent requirements of area and power consumption imposed by the targeted spatial resolution. This work describes a methodology to optimize the design of time-to-digital converter (TDC)-based timing electronics that takes advantage of the asymmetrical shape of the pulse at the output of the analog front-end (AFE). Following that methodology, a power and area efficient implementation fully compatible with the RD50-MPW3 solution is proposed. Simulation results show that the proposed solution offers a time resolution of 2.08 ns for a range of energies from 1000 e− to 20,000 e−, with minimum area and zero quiescent in-pixel power consumption

العلاقة: SENSORS, 23 (13), 5844.; PID2019-107258RB-C31; https://www.mdpi.com/1424-8220/23/13/5844Test; https://idus.us.es/handle//11441/147719Test

الإتاحة: https://idus.us.es/handle//11441/147719Test

المؤلفون: Enrique López-Morillo, Clara Luján-Martínez, José Hinojo-Montero, Fernando Márquez-Lasso, Francisco Rogelio Palomo, Fernando Muñoz-Chavero

المصدر: Sensors; Volume 23; Issue 13; Pages: 5844

مصطلحات موضوعية: depleted monolithic active pixel sensors (DMAPSs), timing, time walk, pixel detector, Large Hadron Collider (LHC), low power, area efficiency

الوصف: Depleted Monolithic Active Pixel Sensors (DMAPSs) are foreseen as an interesting choice for future high-energy physics experiments, mainly because of the reduced fabrication costs. However, they generally offer limited time resolution due to the stringent requirements of area and power consumption imposed by the targeted spatial resolution. This work describes a methodology to optimize the design of time-to-digital converter (TDC)-based timing electronics that takes advantage of the asymmetrical shape of the pulse at the output of the analog front-end (AFE). Following that methodology, a power and area efficient implementation fully compatible with the RD50-MPW3 solution is proposed. Simulation results show that the proposed solution offers a time resolution of 2.08 ns for a range of energies from 1000 e− to 20,000 e−, with minimum area and zero quiescent in-pixel power consumption.

وصف الملف: application/pdf

العلاقة: Physical Sensors; https://dx.doi.org/10.3390/s23135844Test

الإتاحة: https://doi.org/10.3390/s23135844Test