Developments toward a Silicon Strip Tracker for the PANDA Experiment

The PANDA detector at the future FAIR facility in Darmstadt will be a key experiment in the understanding of the strong interaction at medium energies where perturbative models fail to describe the quark-quark interaction. An important feature of the detector system is the ability to reconstruct secondary decay vertices of short-lived intermediate states by means of a powerful particle tracking system with the the Micro-Vertex Detector (MVD) as central element to perform high-resolution charmonium and open-charm spectroscopy. The MVD is conceived with pixel detectors in the inner parts and double-sided silicon strip detectors at the outer half in a very lightweight design. The PANDA detector system shall be operated in a self-triggering broadband acquisition mode. Implications on the read-out electronics and the construction of the front-end assemblies are analyzed and evaluation of prototype DSSD-detectors wrt. signal-to-noise ratio, noise figures, charge sharing behavior, spacial resolution and radiation degradation discussed. Methods of electrical sensor characterization with different measurement setups are investigated which may be useful for future large-scale QA procedures. A novel algorithm for recovering multiple degenerate cluster hit patterns of double-sided strip sensors is introduced and a possible architecture of a Module Data Concentrator ASIC (MDC) aggregating multiple front-end data streams conceived. A first integrative concept for the construction and assembly of DSSD modules for the barrel part of the MVD is introduced as a conclusion of the thesis. Furthermore, a detailed description of a simplified procedure for the calculation of displacement damage in compound materials is given as reference which was found useful for the retrieval of non-ionizing energy loss for materials other than silicon.Der PANDA Detektor im zukünftigen FAIR-Beschleunigerkomplex in Darmstadt wird ein Schlüsselexperiment im Verständnis der starken Wechselwirkung bei mittleren Energien, bei denen kein Zugang über perturbative Methoden zur Quark-Quark Interaktion existiert, sein. Eine wichtige Eigenschaft des Detektorsystems, die Ortsrekonstruktion sekundärer Zerfallsvertizes kurzlebiger Zwischenzustände, wird dabei durch ein Spurverfolgungssystem mit dem Mikro-Vertex Detektor (MVD) als wichtigstem Element zur hochauflösenden Charmoniumund Open-Charm Spektroskopie garantiert. Der MVD ist konzipiert als leichtgewichtiges, geteiltes Silizium-Detektorsystem mit Pixeldetektoren im inneren Bereich und doppelseitigen Streifendetektoren (DSSD) in den äußeren Regionen. Das PANDA Detektorsystem soll in einem selbstgetriggertem Regime Daten breitbandig und ohne Totzeitverluste verarbeiten können. Die sich daraus ergebenden Implikationen auf den Aufbau der Ausleseelektronik und der Front-end-Baugruppen werden analysiert und es werden Ergebnisse von Messungen an DSSD-Prototypen im Hinblick auf Signal-zu-Rausch-Verhältnis, Rauscheigenschaften, Ladungsteilungsverhalten, Ortsauflösung und Bestrahlungstoleranz diskutiert. Methoden zur elektrischen Charakterisierung von Sensoren werden untersucht, die bei zukünftigen großangelegten QA-Untersuchungen nützlich eingesetzt werden können. Ein neuartiger Cluster- Korrelationsalgorithmus, welcher mehrfach entartete Clusterhit-Muster zu erkennen vermag wird ebenso vorgestellt wie eine mögliche Architektur des noch zu entwickelnden Module-Data- Concentrator ASIC (MDC), welcher die Datenströme der Front-end Chips auf Modulebene zusammenfassen soll. Ein erstes integratives Konzept für Konstruktion und Zusammenbau von DSSD-Modulen des Barrel-Bereichs des MVD wird im Abschluss der Dissertation vorgestellt. Darüber hinaus wird eine detaillierte Beschreibung einer vereinfachten Vorschrift zur Berechnung des Versetzungsschadens durch Neutronen in zusammengesetzten Stoffen angegeben, welche sich als nützlich für die Ableitung des nicht-ionisierenden Energieverlustes in Materialien neben Silizium erwiesen hat

Are Cosmic Neutrons a Threat to Pacemakers? - Testing SRAMs with an Am-Be Neutron Source

Introduction: Effects of cosmic radiation can impair pacemakers and other active implanted medical devices (AIMDs). There are several publications about devices showing irregular function during or after air-travel most likely caused by subatomic particles from space (Clair, Williams, Hygaard, & Saavedra, 2013; Ferrick, Bernstein, Aizer, & Chinitz, 2008; Paz, Teodorovich, Kogan, & Swissa, 2017). Furthermore, numerous radiation related malfunctions of unknown origin have been reported in the Manufacturers and User Facility Device Experience (MAUDE) database in recent years, some of which caused symptoms or led to the exchange of the device. These described malfunctions are most likely caused by SEE in the memory of the AIMD. Severe errors in the executed stimulation program are usually detected and corrected by the device itself through a power-on-reset. However, this procedure switches it to safety mode where stimulation parameters can be changed. Ultimately, this can lead to the pacemaker syndrome or unnecessary shocks of defibrillators. The problem of the susceptibility to particle radiation of medical devices is already well-known from radiation therapy. Therefore, various protective measures have been established for patients in recent years to avoid complications in this radiation environment (Gauter-Fleckenstein et al., 2015). Nevertheless, for developing and applying radiation protection measures to patients with AIMDs in further radiation environments, such as at aviation altitudes or during severe space weather events, the assessment of the risk of malfunction for AIMDs is necessary. [...

Measurement of PET isotope production cross sections for protons and carbon ions on carbon and oxygen targets for applications in particle therapy range verification

International audienceMeasured cross sections for the production of the PET isotopes , and from carbon and oxygen targets induced by protons (40–220 ) and carbon ions (65–430 ) are presented. These data were obtained via activation measurements of irradiated graphite and beryllium oxide targets using a set of three scintillators coupled by a coincidence logic. The measured cross sections are relevant for the PET particle range verification method where accurate predictions of the emitter distribution produced by therapeutic beams in the patient tissue are required. The presented dataset is useful for validation and optimization of the nuclear reaction models within Monte Carlo transport codes. For protons the agreement of a radiation transport calculation using the measured cross sections with a thick target PET measurement is demonstrated

Physics with Positron Beams at Jefferson Lab 12 GeV

Positron beams, both polarized and unpolarized, are identified as essential ingredients for the experimental program at the next generation of lepton accelerators. In the context of the Hadronic Physics program at the Jefferson Laboratory (JLab), positron beams are complementary, even essential, tools for a precise understanding of the electromagnetic structure of the nucleon, in both the elastic and the deep-inelastic regimes. For instance, elastic scattering of (un)polarized electrons and positrons off the nucleon allows for a model independent determination of the electromagnetic form factors of the nucleon. Also, the deeply virtual Compton scattering of (un)polarized electrons and positrons allows us to separate unambiguously the different contributions to the cross section of the lepto-production of photons, enabling an accurate determination of the nucleon Generalized Parton Distributions (GPDs), and providing an access to its Gravitational Form Factors. Furthermore, positron beams offer the possibility of alternative tests of the Standard Model through the search of a dark photon or the precise measurement of electroweak couplings. This letter proposes to develop an experimental positron program at JLab to perform unique high impact measurements with respect to the two-photon exchange problem, the determination of the proton and the neutron GPDs, and the search for the $A^{\prime}$ dark photon