Deflections in Magnet Fringe Fields

A transverse multipole expansion is derived, including the longitudinal components necessarily present in regions of varying magnetic field profile. It can be used for exact numerical orbit following through the fringe field regions of magnets whose end designs introduce no extraneous components, {\it i.e.} fields not required to be present by Maxwell's equations. Analytic evaluations of the deflections are obtained in various approximations. Mainly emphasized is a ``straight-line approximation'', in which particle orbits are treated as straight lines through the fringe field regions. This approximation leads to a readily-evaluated figure of merit, the ratio of r.m.s. end deflection to nominal body deflection, that can be used to determine whether or not a fringe field can be neglected. Deflections in ``critical'' cases (e.g. near intersection regions) are analysed in the same approximation.Comment: To be published in Physical Review

Playback of ultrasonic vocalizations in rats: habituation, response calls, and drug effects

Rats are highly social animals. They have developed a variety of social behaviors including communication via so-called ultrasonic vocalizations (USV). Among these USV, two types can be distinguished in juvenile and adult rats. Appetitive 50-kHz USV are thought to represent a positive affective state, whereas aversive 22-kHz USV are supposed to depict a negative affective state. Playback of positive 50-kHz USV induces an approach behavior in rats as seen by their approach behavior to the sound source. Previous studies have shown that this behavior is only detectable during the first presentation, whereas a quick habituation towards 50-kHz USV results in the rats not approaching the 50-kHz USV playback a second time, even after several days. This habituation phenomenon seems to rely on learning and memory mechanisms. However, its underlying mechanisms have been studied scarcely so far. This dissertation revealed three factors influencing the habituation phenomenon. First, habituation was dependent on stocks. It was only present in Wistar but not Sprague-Dawley rats. Second, habituation could be prevented with treatment of the dopaminergic agonist d-amphetamine before the second 50-kHz USV playback. Third, habituation was state-dependent. It was shown that when the pharmacologically induced internal state changed between the two playbacks, no habituation occurred. Furthermore, the reciprocal nature of USV was investigated in this dissertation. Calls in response towards 50-kHz USV playback had been reported before, but this dissertation is the first to characterize response calls. We showed that response calls towards 50-kHz playback are around frequencies of 30 kHz, have a rather short duration of 0.3 s and hardly any frequency modulation. These parameters resemble aversive 22-kHz calls, which are unlikely to be found in an appetitive paradigm as the 50-kHz USV playback. Feasible functions of these response calls might be a frustrated state due to expectation violation after playback, appeasement calls to pacify the potential play partner indicated by the playback, or they might serve as social contact calls to establish proximity. Taken together, the findings of this dissertation shed light on the reciprocal nature of USV communication indicated by response calls towards 50-kHz USV playback and present possible mechanisms how to overcome the habituation phenomenon. This provides tools to further investigate neurodevelopmental disorders where communication and social behavior is impaired, such as autism spectrum disorder or the Angelman Syndrome, as well as affective disorders

Long term nonlinear propagation of uncertainties in perturbed geocentric dynamics using automatic domain splitting

Current approaches to uncertainty propagation in astrodynamics mainly refer tolinearized models or Monte Carlo simulations. Naive linear methods fail in nonlinear dynamics, whereas Monte Carlo simulations tend to be computationallyintensive. Differential algebra has already proven to be an efficient compromiseby replacing thousands of pointwise integrations of Monte Carlo runs with thefast evaluation of the arbitrary order Taylor expansion of the flow of the dynamics. However, the current implementation of the DA-based high-order uncertainty propagator fails in highly nonlinear dynamics or long term propagation. We solve this issue by introducing automatic domain splitting. During propagation, the polynomial of the current state is split in two polynomials when its accuracy reaches a given threshold. The resulting polynomials accurately track uncertainties, even in highly nonlinear dynamics and long term propagations. Furthermore, valuable additional information about the dynamical system is available from the pattern in which those automatic splits occur. From this pattern it is immediately visible where the system behaves chaotically and where its evolution is smooth. Furthermore, it is possible to deduce the behavior of the system for each region, yielding further insight into the dynamics. In this work, the method is applied to the analysis of an end-of-life disposal trajectory of the INTEGRAL spacecraft

CW high intensity non-scaling FFAG proton drivers

Accelerators are playing increasingly important roles in basic science, technology, and medicine including nuclear power, industrial irradiation, material science, and neutrino production. Proton and light-ion accelerators in particular have many research, energy and medical applications, providing one of the most effective treatments for many types of cancer. Ultra high-intensity and high-energy (GeV) proton drivers are a critical technology for accelerator-driven sub-critical reactors (ADS) and many HEP programs (Muon Collider). These high-intensity GeV-range proton drivers are particularly challenging, encountering duty cycle and space-charge limits in the synchrotron and machine size concerns in the weaker-focusing cyclotrons; a 10-20 MW proton driver is not presently considered technically achievable with conventional re-circulating accelerators. One, as-yet, unexplored re-circulating accelerator, the Fixed-field Alternating Gradient, or FFAG, is an attractive alternative to the cyclotron. Its strong focusing optics are expected to mitigate space charge effects, and a recent innovation in design has coupled stable tunes with isochronous orbits, making the FFAG capable of fixed-frequency, CW acceleration, as in the classical cyclotron. This paper reports on these new advances in FFAG accelerator technology and references advanced modeling tools for fixed-field accelerators developed for and unique to the code COSY INFINITY.Comment: 3 pp. Particle Accelerator, 24th Conference (PAC'11) 2011. 28 Mar - 1 Apr 2011. New York, US