Development of a Pulse Shape Analysis for the CONUS Experiment

The CONUS experiment, using four 1 kg-sized point-contact high-purity germanium detectors (HPGe), aims to detect coherent elastic neutrino-nucleus scattering (CEνNS) in the fully coherent regime. It is located close to the reactor core of the nuclear power plant in Brokdorf, Germany. For the success of the experiment excellent background suppression is crucial. A new opportunity for further background reduction is the analysis of the pulse shape of each event. Depending on whether the incoming particle interacts in the fully depleted bulk region or in an outer layer of the Ge diode, the resulting pulse shapes are different. In this thesis, a technique will be presented to discriminate the different low energy interactions based on a rise time fit of their pulses. It will be shown that the rise time fit analysis can be used down to energies of ∼ 200 eV and that an additional background reduction of about 25 % in the region of interest for CEνNS is achievable. For this purpose, a new method will be presented to calculate the efficiencies of a pulse shape cut, including systematic uncertainties. The universality of the rise time fit is shown by demonstrating the feasibility of discriminating multi-site events at high energies

Prenatal Determinants of Early Behavioral and Cognitive Development: The Generation R Study

Child development is fascinating in its complexity and for more than 120 years psychologists have applied scientific methods to its examination, but the concept of child development did not receive much attention from philosophers during classical antiquity and the Middle Ages (Oerter & Montada, 2002). Based on his analysis of art work the historian Philippe Ariès (1962) assumed that the concept of childhood did not exist in the medieval period and concluded that children were considered as little adults. In the medieval period, most young people were apprentices, became workers in the fields and normally entered the adult world very early in life (Ariès, 1962). Very important for the emergence of the concept of child development were two opposing philosophical views of human nature from the 17th and 18th century (De- Hart, Sroufe, & Cooper, 2004). On the one hand, the English empiricist John Locke (1632-1704) argued that at birth the mind of a child is tabula rasa, “a totally blank slate to be written on by life’s experience” (DeHart et al., 2004). This blank slate view suggests that differences among children can be explained in terms of differences in their environments (Boyd & Bee, 2009). On the other hand, Jean Jacques Rousseau (1712-1778) claimed that all human beings possess innate goodness and seek out experiences that help them grow (Boyd & Bee, 2009). According to Rousseau, child development unfolds naturally in positive ways as long as society allows it to do so (Boyd & Bee, 2009). To this day, these two opposing views of human nature are still reflected in the so-called nature-nurture debate addressing of how heredity and environment influence development

Automated Reconstruction of Particle Cascades in High Energy Physics Experiments

We present a procedure for reconstructing particle cascades from event data measured in a high energy physics experiment. For evaluating the hypothesis of a specific physics process causing the observed data, all possible reconstruction versions of the scattering process are constructed from the final state objects. We describe the procedure as well as examples of physics processes of different complexity studied at hadron-hadron colliders. We estimate the performance by 20 microseconds per reconstructed decay vertex, and 0.6 kByte per reconstructed particle in the decay trees.Comment: 8 pages, 2 figures. Submitted to Computational Science & Discover

Recurrent shell infall events in a B0.5e star: HD 58978 1979-1988

Infall from the circumstellar envelope onto the bright B0.5 IVe star, HD 58978 was studied. The IUE data indicate that the star was surrounded by a low and moderately ionized circumstellar shell at least 12 times between 1979 and 1988. During 6 of these episodes, the signatures of cool circumstellar material were redshifted with respect to the photosphere by 20 to 80 km/sec. The data indicate that the transition from infall to minimal shell absorption can occur in under 10 days, and are consistent either with infall phases lasting up to 6 months, or with infall episodes shorter than 10 to 15 days. The long term behavior of the shell episodes is compared with variability in the stellar wind

Choice of tip, signal stability, and practical aspects of piezoresponse-force-microscopy

Piezoresponse force-microscopy (PFM) has become the standard tool to investigate ferroelectrics on the micro- and nanoscale. However, reliability of PFM signals is often problematic and their quantification is challenging and thus not widely applied. Here, we present a study of the reproducibility of PFM signals and of the so-called PFM background signal which has been reported in the literature. We find that PFM signals are generally reproducible to certain extents. The PFM signal difference between 180°domains on periodically poled lithium niobate (PPLN) is taken as the reference signal in a large number of measurements, carried out in a low frequency regime (30-70 kHz). We show that in comparison to Pt coated tips, diamond coated tips exhibit improved signal stability, lower background signal, and less imaging artifacts related to PFM which is reflected in the spread of measurements. This is attributed to the improved mechanical stability of the conductive layer. The average deviation of the mean PFM signal is 38.3%, for a diamond coated tip. Although this deviation is relatively high, it is far better than values from the literature which showed a deviation of approx. 73.1%. Additionally, we find that the average deviation of the background signal from 0 is 11.6% of the PPLN domain contrast. Thus, the background signal needs to be taken into account when quantifying PFM signals and should be subtracted from PFM signals. Those results are important for quantification of PFM signals, since PPLN might be used for this purpose when PFM signals measured on PPLN are related to its macroscopic d33 coefficient. Finally, the crucial influence of sample polishing on PFM signals is shown and we recommend to use a multistep polishing route with a final step involving 200 nm sized colloidal silica particles