26 research outputs found
Implementation of the VMM ASIC in the Scalable Readout System
No full textThe Scalable Readout System (SRS) developed by the RD51 collaboration is a versatile and multi-purpose approach, which is used with different front-end chips to transfer data from detectors to computers. Targeting mainly micro-pattern gaseous detectors, the system is also applicable for silicon strip or pad detectors. The most frequently used front-end chip today is the APV25, originally developed for the CMS pixel detector. In the scope of the ATLAS New Small Wheel upgrade, a new front-end chip, the VMM, is developed, which has significantly improved specifications compared to the APV25.
We report on the implementation of the VMM in the Scalable Readout System carried out by the RD51 collaboration in the framework of a detector project related to the European Spallation Source ERIC. Due to the hierarchical design of the Scalable Readout System, only specific parts of the readout chain need to be adapted or designed, which is the carrier board for the front-end chip, an adapter card that connects to the common hardware of the system and the firmware for a field programmable gate array. In addition, we have developed dedicated software for slow control, data acquisition and online monitoring. The readout system has been tested in the laboratory and in particle beams and we present results which proof the functioning of the system, even though it is still in a prototype state.The Scalable Readout System (SRS) developed by the RD51 collaboration is a versatile and multi-purpose approach, which is used with different front-end chips to transfer data from detectors to computers. Targeting mainly micro-pattern gaseous detectors, the system is also applicable for silicon strip or pad detectors. The most frequently used front-end chip today is the APV25, originally developed for the CMS pixel detector. In the scope of the ATLAS New Small Wheel upgrade, a new front-end chip, the VMM, is developed, which has significantly improved specifications compared to the APV25
Treatment of radioactively contaminated wastewater in nuclear medicine facilities
No full textDiese Arbeit basiert auf einer Literaturrecherche und beschäftigt sich mit dem Abwasser aus nuklearmedizinischen Einrichtungen. Werden Patienten radioaktive Substanzen verabreicht, verweilen diese für eine gewisse Zeit im Körper und werden dann über die Atemluft sowie Körperflüssigkeiten und Exkremente ausgeschieden. Abhängig von den physikalischen Eigenschaften der inkorporierten Stoffe, ist die Höhe der potenziellen Gefahr, die von diesen Ausscheidungen ausgeht. Um das Personal dieser Einrichtungen sowie die Allgemeinbevölkerung vor gesundheitlichen Schäden durch Strahlung zu schützen, gibt es strenge Vorschriften und Grenzwerte, die bei der Ableitung des Abwassers ins Kanalsystem einzuhalten sind. Nach heutigem Stand der Technik, wird das Abwasser aus den Therapiestationen in speziellen Tanks zwischengelagert, diese werden als Abklinganlagen bezeichnet. In diesen Behältern wird das Abwasser gelagert, bis die Radioaktivität unter den behördlich festgelegten Grenzwert fällt und sicher abgeleitet werden kann.
Die Arbeit gibt einen Überblick, welche grundlegenden Überlegungen in die Planung von Abklinganlagen einfließen müssen, von den Anforderungen an die Nasszellen der Patientenzimmer bis hin zur Entleerung ins kommunale Kanalsystem. Abschließend stellt die Autorin neue Ansätze zur Abwasserbehandlung vor, welche das Potential haben in Zukunft die herkömmlichen Abklinganlagen zu ersetzen.This thesis is based on a literature research and deals with wastewater from nuclear medicine facilities. If patients are treated with radiopharmaceuticals, they stay in the body for a certain period and are then excreted via the respiratory air as well as body fluids and feces. The potential hazard of this excretion is depending on the physical properties of the incorporated substances. In order to protect the personnel of these facilities as well as the general population against health damage caused by radiation, there are strict regulations and thresholds to comply with when discharging the wastewater into the sewer system. According to the current state of the art, the wastewater from the therapy stations is stored in special containers, known as decay tanks. Their function is to store the liquid waste until its activity drops below a threshold determined by the authority, before it can be safely released into the sewer system.
The work gives an overview of the basic considerations that must be taken into account in the planning process of decay systems, from the requirements of the wet rooms of the patient rooms to the discharge into the municipal canal system. Finally, the author presents new approaches to wastewater treatment, which have the potential to replace conventional decay systems in the future
Observation of strong wavelength-shifting in the argon-tetrafluoromethane system
No full textWe report the scintillation spectra of Ar/CF4 mixtures in the range 210–800 nm, obtained under X-ray irradiation for various pressures (1–5 bar) and concentrations (0%–100%). Special care was taken to eliminate effects related to space charge and charge recombination, so that results can be extrapolated following conventional wisdom to those expected for minimum ionizing particles under the typical electric fields employed in gaseous instrumentation. Our study sheds light into the microscopic pathways leading to scintillation in this family of mixtures and reinvigorates the prospects of use in next-generation scintillation-based chambers.We report the scintillation spectra of Ar-CF mixtures in the range 210-800~nm, obtained under X-ray irradiation for various pressures (1-5~bar) and concentrations (0-100%). Special care was taken to eliminate effects related to space charge and recombination, so that results can be extrapolated following conventional wisdom to those expected for minimum ionizing particles under the typical electric fields employed in gaseous instrumentation. Our study sheds light into the microscopic pathways leading to scintillation in this family of mixtures
Quantum Systems for Enhanced High Energy Particle Physics Detectors
No full textDevelopments in quantum technologies in the last decades have led to a wide range of applications, but have also resulted in numerous novel approaches to explore the low energy particle physics parameter space. The potential for applications of quantum technologies to high energy particle physics endeavors has however not yet been investigated to the same extent. In this paper, we propose a number of areas where specific approaches built on quantum systems such as low-dimensional systems (quantum dots, 2D atomic layers) or manipulations of ensembles of quantum systems (single atom or polyatomic systems in detectors or on detector surfaces) might lead to improved high energy particle physics detectors, specifically in the areas of calorimetry, tracking or timing
Spatial resolution studies using point spread function extraction in optically read out Micromegas and GEM detectors
No full textInternational audienceOptically read out gaseous detectors are used in track reconstruction and imaging applications requiring high granularity images. Among resolution-determining factors, the amplification stage plays a crucial role and optimisations of detector geometry are pursued to maximise spatial resolution. To compare MicroPattern Gaseous Detector (MPGD) technologies, focused low-energy X-ray beams at the SOLEIL synchrotron facility were used to record and extract point spread function widths with Micromegas and GEM detectors. Point spread function width of 108 \microns for Micromegas and 127 \microns for GEM foils were extracted. The scanning of the beam with different intensities, energies and across the detector active region can be used to quantify resolution-limiting factors and improve imaging detectors using MPGD amplification stages
Radiation imaging with optically read out GEM-based detectors
No full textModern imaging sensors allow for high granularity optical readout of radiation detectors such as MicroPattern Gaseous Detectors (MPGDs). Taking advantage of the high signal amplification factors achievable by MPGD technologies such as Gaseous Electron Multipliers (GEMs), highly sensitive detectors can be realised and employing gas mixtures with strong scintillation yield in the visible wavelength regime, optical readout of such detectors can provide high-resolution event representations. Applications from X-ray imaging to fluoroscopy and tomography profit from the good spatial resolution of optical readout and the possibility to obtain images without the need for extensive reconstruction. Sensitivity to low-energy X-rays and energy resolution permit energy resolved imaging and material distinction in X-ray fluorescence measurements. Additionally, the low material budget of gaseous detectors and the possibility to couple scintillation light to imaging sensors via fibres or mirrors makes optically read out GEMs an ideal candidate for beam monitoring detectors in high energy physics as well as radiotherapy. We present applications and achievements of optically read out GEM-based detectors including high spatial resolution imaging and X-ray fluorescence measurements as an alternative readout approach for MPGDs. A detector concept for low intensity applications such as X-ray crystallography, which maximises detection efficiency with a thick conversion region but mitigates parallax-induced broadening is presented and beam monitoring capabilities of optical readout are explored. Augmenting high resolution 2D projections of particle tracks obtained with optical readout with timing information from fast photon detectors or transparent anodes for charge readout, 3D reconstruction of particle trajectories can be performed and permits the realisation of optically read out time projection chambers. Combining readily available high performance imaging sensors with compatible scintillating gases and the strong signal amplification factors achieved by MPGDs makes optical readout an attractive alternative to the common concept of electronic readout of radiation detectors. Outstanding signal-to-noise ratios and robustness against electronic noise allow unprecedented imaging capabilities for various applications in fields ranging from high energy physics to medical instrumentation
Live event reconstruction in an optically read out GEM-based TPC
No full textCombining strong signal amplification made possible by Gaseous Electron Multipliers (GEMs) with the high spatial resolution provided by optical readout, highly performing radiation detectors can be realized. An optically read out GEM-based Time Projection Chamber (TPC) is presented. The device permits 3D track reconstruction by combining the 2D projections obtained with a CCD camera with timing information from a photomultiplier tube. Owing to the intuitive 2D representation of the tracks in the images and to automated control, data acquisition and event reconstruction algorithms, the optically read out TPC permits live display of reconstructed tracks in three dimensions. An Ar/CF 4 (80/20%) gas mixture was used to maximize scintillation yield in the visible wavelength region matching the quantum efficiency of the camera. The device is integrated in a UHV-grade vessel allowing for precise control of the gas composition and purity. Long term studies in sealed mode operation revealed a minor decrease in the scintillation light intensity
X-ray imaging with Micromegas detectors with optical readout
No full textIn the last years, optical readout of Micromegas gaseous detectors has been
achieved by implementing a Micromegas detector on a glass anode coupled to a
CMOS camera. Effective X-ray radiography was demonstrated using integrated
imaging approach. High granularity values have been reached for low-energy
X-rays from radioactive sources and X-ray generators.
Detector characterization with X-ray radiography has led to two applications:
neutron imaging for non-destructive examination of highly gamma-ray emitting
objects and beta imaging for the single cell activity tagging in the field of
oncology drug studies.
First measurements investigating the achievable spatial resolution of the
glass Micromegas detector at the SOLEIL synchrotron facility with a
high-intensity and flat irradiation field will be shown in this article.Comment: 6 pages, 4 figures, 7th International Conference on Micro Pattern
Gaseous Detectors, 11-16 December 20223, Weizmann Institute of Science,
Rehovot, Israe
The planispherical chamber: A parallax-free gaseous X-ray detector for imaging applications
No full textCrystallography or X-ray fluorescence experiments which require good signal to noise ratios and high position resolution can take advantage of the outstanding signal amplification capabilities of MicroPattern Gaseous Detectors (MPGDs) such as Gaseous Electron Multipliers (GEMs) coupled with the position resolution achieved by optical readout realized with CCD or CMOS cameras. Increasing the detection probability of incident radiation with thicker drift volumes in these detectors leads to a spatial resolution-limiting parallax error when employing parallel electric field lines in the drift region
Integration of CVD graphene in gaseous electron multipliers for high energy physics experiments
No full textInternational audienceTo enhance the performance of micro-patterned gaseous detectors (MPGDs) to meet thechallenging requirements of future high energy physics (HEP) experiments, two-dimensional (2D)materials are attractive candidates to address the back flow of positive ions, which affectsdetector performance by distorting electric field lines. In this context, graphene is promisingto work as selective filter for ion back flow suppression, being transparent to electrons while atthe same time blocking ions. Also, graphene membranes can physically separate drift andamplification regions of the detectors, offering additional flexibility in the choice of gasmixtures and allowing independent optimizations of detector sensitivity and electronmultiplication processes. Here we present an approach to integrate graphene grown via chemicalvapor deposition (CVD) on gaseous electron multiplier (GEM) prototypes via a wet transferprocedure in order to suspend graphene over thousands of holes with 60 μm diameter and overcomethe challenges encountered due to process steps involving liquids, mostly related with thecapillary effects during drying and evaporation of them. In order to overcome the risk of damagingthe membrane and decreasing the yield of suspended 2D material membranes, critical point dryer(CPD) and inverted floating method (IFM) procedures are investigated. In addition to thenecessity to cover the full holes in the active area, polymeric residuals have to be minimized inorder to evaluate the graphene transparency at the electron energies (i.e., < 15 eV) typicallyobtained in the operating conditions, measurements in these energy ranges are still not deeplyinvestigated
