R&D Proposal Development of Micro-Pattern Gas Detector Technologies

Development of advanced gas-avalanche detector technologies and associated electronic-readout systems for applications in basic and applied researc

Particle Physics Reference Library

This second open access volume of the handbook series deals with detectors, large experimental facilities and data handling, both for accelerator and non-accelerator based experiments. It also covers applications in medicine and life sciences. A joint CERN-Springer initiative, the “Particle Physics Reference Library” provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A,B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access

Perspectives of Nuclear Physics in Europe: NuPECC Long Range Plan 2010

The goal of this European Science Foundation Forward Look into the future of Nuclear Physics is to bring together the entire Nuclear Physics community in Europe to formulate a coherent plan of the best way to develop the field in the coming decade and beyond.<p></p> The primary aim of Nuclear Physics is to understand the origin, evolution, structure and phases of strongly interacting matter, which constitutes nearly 100% of the visible matter in the universe. This is an immensely important and challenging task that requires the concerted effort of scientists working in both theory and experiment, funding agencies, politicians and the public.<p></p> Nuclear Physics projects are often “big science”, which implies large investments and long lead times. They need careful forward planning and strong support from policy makers. This Forward Look provides an excellent tool to achieve this. It represents the outcome of detailed scrutiny by Europe’s leading experts and will help focus the views of the scientific community on the most promising directions in the field and create the basis for funding agencies to provide adequate support.<p></p> The current NuPECC Long Range Plan 2010 “Perspectives of Nuclear Physics in Europe” resulted from consultation with close to 6 000 scientists and engineers over a period of approximately one year. Its detailed recommendations are presented on the following pages. For the interested public, a short summary brochure has been produced to accompany the Forward Look.<p></p&gt

Study of channeling phenomena in bent crystals: the new frontiers

More or less 30 years ago, it was experimentally demonstrated how a bent crystal can become a magnet: an object 1 mm thick, a couple of mm wide and a few cm high is, in fact, capable of steering particles as a dipole of several tens of Tesla. Exploiting this feature, from September 2006 the H8RD22 collaboration is testing several bent crystals in order to develop a crystal based collimation system for LHC: in very high energy accelerators, in fact, the typical multi-stage collimation system (that must be very efficient and must tolerate very high radiation) is expected not to allow to reach the nominal luminosity, limiting it to 40% of the desired value. A bent crystal could play a key role being a clever collimator: it is able to steer particles in a given direction with a high efficiency, thus increasing the cleaning efficiency, reducing the constraints on the alignment of the secondary collimator and finally increasing luminosity. But bent crystals are not only collimation: the radiation emitted by light particles in such crystals could be a real breakthrough for several applications, from the the generation of intense gamma beams for a positron source to the collimation of electron-positron beams at the future linear collider. This study is still an open field, given the constraints on the beam and on the experimental setup. The goal of this thesis work is to give an insight of the physics of bent crystals from several poin ts of view: their behavior with heavy and light particles, the possible applications in different fields and the experimental results obtained in recent beam tests with 400 GeV/c and 180 GeV/c heavy and light particles

Enhancement of the UK primary standard for absorbed dose for proton radiotherapy

With the implementation of proton beam therapy; modern radiotherapy treatments have better outcomes than ever before. Likewise, the development of spatially fractionated radiotherapy treatments have shown tremendous potential in pre-clinical studies for improving patient outcomes. Both of these implementation come at the cost of increasing complexity, providing a greater challenge for both routine quality assurance and primary standard dosimetry. Simultaneously, recent advances in the field of silicon radiation detectors offer a possible solution for high resolution real-time monitoring would would increase confidence in the dosimetry. This thesis describes the application of Silicon Strip Detectors (SSD) and Complementary Metal-Oxide Semiconductor (CMOS) devices to X-ray and Proton beam therapies with the intention to develop new methods of quality assurance and a combined system using the NPL Graphite Calorimeter for proton radiotherapy. A combined system using a large-format CMOS is tested in 6 MV X-ray beams at the NPL, verifying the concept and providing a proof of principle. These measurements produced some unexpected results, which required the development of a model of the Calorimeter in COMSOL, a finite-element simulation software package, to study and better understand the internal heat flow. The developed model can use parameterised beam data acquired by an independent silicon detector (whether CMOS or SSD detectors) as a heat source for coupled simulations of delivered beams. After validating against experimental results, the model was subjected to fields of radiation representative of Pencil beam scanning (PBS), providing confidence in the effectiveness of the NPL Graphite Calorimeter in these radiation beams

On the spectrometry of laser-accelerated particle bunches and laser-driven proton radiography

The increased availability of high-power laser systems operating with relatively high repetition rates (∼ 1 Hz), such as installed in the upcoming Centre for Advanced Laser Applications (CALA), are pushing laser-driven ion acceleration towards applications beyond fundamental research. With energies of laser-accelerated protons approaching 100 MeV, great interest in the community is devoted to biomedical applications like small-animal irradiation and imaging of biological samples. Such laser-accelerated ion bunches exhibit unique properties as compared to conventionally accelerated particles from electrostatic or radio-frequency driven accelerators. Among these characteristics are high beam intensities (∼ 10^9 protons/ns), a broad energy distribution (∼ 100%) and a strong electromagnetic pulse generated in the laser-plasma interaction. Due to these peculiar properties, conventional beam monitoring devices as installed e.g. in clinical ion beam facilities are not suitable for the characterization of laser-accelerated ion bunches and no system is available to date allowing for online beam monitoring simultaneous to an application. Within the framework of this thesis, two approaches for characterization of laser-accelerated proton bunches in terms of energy spectrum have been investigated and prototype systems have been developed and tested. The first setup is based on the time-of-flight (TOF) technique. The continuous energy distribution is deconvolved from the TOF signal current measured by a novel thin silicon detector which is exposed to temporally divergent polyenergetic proton bunches, taking into account the finite response function of the detector and the associated readout electronics. Measurements were performed in the energy range up to 20 MeV using nanosecond-short and passively energy-modulated proton bunches from a Tandem accelerator, as well as using laser-accelerated proton bunches obtained in experiments at the Laboratory for Extreme Photonics. A comparison of the reconstructed energy spectra to Monte Carlo simulations and measurements using a magnetic spectrometer has shown promising agreement. In the studied energy range and for the tested TOF distances, the reconstructed particle number and the mean reconstructed energy agreed with expectations within 12% and 2%, respectively. In the second investigated setup, the sensor chip of a hybrid pixel detector Timepix was irradiated edge-on with protons in the energy interval between 17 and 20 MeV. Spatial information along one axis perpendicular to the proton beam direction was obtained due to the pixelation of the detector. Although this spectrometric setup is only suitable for low proton fluences (< 7 × 10 3 protons/cm 2 ) per acquisition frame, which is far below typically obtained fluences from laser-ion acceleration experiments, the developed spectrum reconstruction method could be applied to other detector types providing a higher saturation limit than the used Timepix detector. As this thesis is dedicated to biomedical applications using laser-accelerated proton bunches, a feasibility study was performed to assess the applicability of laser-driven proton radiography of millimeter to centimeter sized objects using pixelated semiconductor detectors and polyenergetic proton bunches in the energy ranges up to 20 MeV and up to 100 MeV. The study was based on Monte Carlo simulations and was supported by a proof of principle experiment with an energy-modulated proton beam from a conventional Tandem accelerator. Sub-mm spatial resolution and density resolution below 3% were found for all objects investigated within this study and the optimized geometric distances. Motivated by the promising results obtained within this thesis, the TOF spectrometer will be implemented as diagnostic device in the laser-ion acceleration setup at CALA in the near future. Moreover, a radiographic imaging setup using laser-accelerated proton bunches and pixelated silicon detector, based on the results obtained within this thesis, is foreseen.Die vermehrte Verfügbarkeit von Hochleistungslasersystemen mit relativ hohen Pulswiederholungsraten (∼ 1 Hz), wie beispielsweise im Centre for Advanced Laser Applications (CALA), öffnen neue Wege für Anwendungen von Laser-Ionen-Beschleunigung, die über die Grundlagenforschung hinausreichen. Da sich die erzielten Energien von laser-beschleunigten Protonen den 100 MeV annähern, steigt das Interesse an biomedizinischen Anwendungen wie beispielsweise Kleintierbestrahlungen und Bildgebung von biologischen Proben. Die Eigenschaften solcher laser-beschleunigter Ionenpulse sind einzigartig verglichen mit konventionell beschleunigten Teilchen von elektrostatischen oder von Beschleunigern basierend auf elektromagnetischen Wechselfeldern. Zu den Merkmalen zählen die hohen Intensitäten (∼ 10^9 Protonen/ns), ein breites Energiespektrum (∼ 100%) und der starke elektromagnetische Puls, der in der Laser-Plasma-Interaktion erzeugt wird. Aufgrund dieser besonderen Eigenschaften sind herkömmliche Strahlüberwachungssysteme, wie beispielsweise in klinischen Ionenstrahleinrichtungen eingesetzt, nicht geeignet. Bisher ist kein System verfügbar, welches eine Echtzeitstrahlüberwachung parallel zu einer Anwendung erlaubt. Im Zuge dieser Arbeit wurden zwei Ansätze zur Charakterisierung laser-beschleunigter Protonenpulse hinsichtlich ihres Energiespektrums untersucht. Prototypen wurden entwickelt und getestet. Der erste Ansatz basiert auf der Flugzeitmessung (time-of-flight - TOF). Die kontinuierliche Energieverteilung wird aus dem gemessenen TOF-Signal herausgefaltet. Dieses wird mit Hilfe eines neuartigen dünnen Siliziumdetektors aufgezeichnet, der dem zeitlich auseinanderlaufenden polyenergetischen Protonenpuls exponiert ist. Die Ansprechfunktion des Detektors und der zugehörigen Ausleseelektronik wird hierbei berücksichtigt. Messungen wurden im Energiebereich bis 20 MeV mit nanosekunden-kurzen und passiv Energie-modulierten Protonenpulsen eines Tandem-Beschleunigers, sowie mit laser-beschleunigten Protonenpulsen am Laboratory for Extreme Photonics, durchgeführt. Vielversprechende Übereinstimmungen wurden beim Vergleich der rekonstruierten Energieverteilung zu Monte-Carlo Simulationen und zu Messungen mit Hilfe eines Magnetspektrometers gefunden. Für den getesteten Energiebereich und TOF-Distanzen waren die Abweichungen zwischen Rekonstruktion und Erwartungen bei Teilchenzahl und mittlerer Energie kleiner als 12%, beziehungsweise 2%. Im zweiten untersuchten Aufbau wurde die Sensorchipkante des hybriden Pixeldetektors Timepix mit Protonen im Energieintervall zwischen 17 und 20 MeV bestrahlt. Räumliche Information entlang einer Achse senkrecht zur Strahlrichtung wurde aufgrund der Pixelierung des Detektors erhalten. Dieser spektrometrische Aufbau ist nur für niedrige Protonenfluenzen (< 7 × 10 3 Protonen/cm 2 ) pro Aufnahmebild, welche weit unter typischen Fluenzen in Laser-Ionen-Beschleunigung liegt, geeignet. Dennoch kann die in dieser Arbeit entwickelte Rekonstruktionsmethode für andere Detektortypen, mit höherer Sättigungsgrenze als der Timepix-Detektor, angewandt werden. Da diese Dissertation das Ziel einer biomedizinische Anwendung von laser-beschleunigten Protonenpulsen verfolgt, wurde eine Studie durchgeführt um die Machbarkeit von laserbeschleunigter Protonenradiographie von Millimeter- bis Zentimeter-großen Objekten und pixelierten Halbleiterdetektoren zu eruieren. Der Energiebereich der polyenergetischen Protonenpulse war hierbei bis 20 MeV und bis 100 MeV. Die Studie basiert auf Monte-Carlo Simulationen und wurde durch ein Proof-of-Principle Experiment mit einem Energiemodulierten Protonenstrahl von einem Tandembeschleuniger unterstützt. Die gefundene räumliche Auflösung und die Dichteauflösung war im sub-Millimeterbereich, bzw. besser als 3% für alle in dieser Studie getesteten Objekte und für die optimierten geometrischen Abstände. Aufgrund der vielversprechenden Ergebnisse, die im Zuge dieser Arbeit gewonnen wurden, wird das Flugzeitspektrometer als diagnostisches System für die Laser-Ionen-Beschleunigung an CALA in naher Zukunft eingesetzt. Desweiteren ist ein Aufbau zur Bildgebung mittels laser-beschleunigter Protonen und einem pixelierten Siliziumdetektor, basierend auf den in dieser Arbeit erzielten Ergebnisse, vorgesehen