The Majorana Collaboration is constructing a prototype system containing 40 kg of HPGe detectors to demonstrate the feasibility and potential of a future tonne-scale experiment to search for ...neutrinoless double-beta (0v BB) decay in 76Ge. In view of the requirement that the next generation of tonne-scale Ge-based 0vBB-decay experiment be capable of probing the neutrino mass scale in the inverted-hierarchy region, a major goal of theMajorana Demonstrator is to demonstrate a path forward to achieving a background rate at or below 1 cnt/(ROI-t-y) in the 4 keV region of interest around the Q-value at 2039 keV. This goal is pursued through a combination of a significant reduction of radioactive impurities in construction materials with analytical methods for background rejection, for example using powerful pulse shape analysis techniques profiting from the p-type point contact HPGe detectors technology. The effectiveness of these methods is assessed using Geant4 simulations of the different background components whose purity levels are constrained from radioassay measurements.
A Dark Matter Search with MALBEK Giovanetti, G. K.; Abgrall, N.; Aguayo, Estanislao ...
Physics procedia,
06/2015, Letnik:
61
Journal Article
The Majorana Demonstrator is an array of natural and enriched high purity germanium detectors that will search for the neutrinoless double-beta decay of 76Ge and perform a search for weakly ...interacting massive particles (WIMPs) with masses below 10 GeV. As part of the Majorana research and development efforts, we have deployed a modified, low-background broad energy germanium detector at the Kimballton Underground Research Facility. With its sub-keV energy threshold, this detector is potentially sensitive to non-Standard Model physics, including interactions with WIMPs. We discuss the backgrounds present in the WIMP region of interest and present results from a WIMP search with 221.49 live days of data from this detector.
Immersive output and effortless input are two core aspects of a virtual reality (VR) experience. We transfer ubiquitous touch interaction with haptic feedback into a virtual environment (VE). The ...movable and cheap real world object supplies an accurate touch detection equal to a ray-casting interaction with a controller. Moreover, the virtual tablet extends the functionality of a real world tablet. Additional information is displayed in mid-air around the touchable area and the tablet can be turned over to interact with both sides. It allows easy to learn and precise system interaction and can even augment the established touch metaphor with new paradigms.
The Majorana Demonstrator will search for neutrinoless-double-beta decay in 76Ge, while establishing the feasibility of a future tonne-scale germanium-based neutrinoless-double-beta decay experiment, ...and performing searches for new physics beyond the Standard Model. The experiment, currently under construction at the Sanford Underground Research Facility in Lead, SD, will consist of a pair of modular high-purity germanium detector arrays housed inside of a compact copper, lead, and polyethylene shield. Through a combination of strict materials qualifications and assay, low-background design, and powerful background rejection techniques, the Demonstrator aims to achieve a background rate in the neutrinoless-double-beta decay region of interest (ROI) of no more than 3cnts/(ROI-t-y). The current status of the Demonstrator is discussed, as are plans for its completion.
We present time-resolved high energy x-ray diffraction (tr-HEXRD),
time-resolved hard x-ray photoelectron spectroscopy (tr-HAXPES) and
time-resolved grazing incidence small angle x-ray scattering ...(tr-GISAXS) data
of the reactive molecular beam epitaxy (RMBE) of $\mathrm{Fe_3O_4}$ ultrathin
films on various substrates. Reciprocal space maps are recorded during the
deposition of $\mathrm{Fe_3O_4}$ on $\mathrm{SrTiO_3(001)}$, MgO(001) and
NiO/MgO(001) in order to observe the temporal evolution of Bragg reflections
sensitive to the octahedral and tetrahedral sublattices of the inverse spinel
structure of $\mathrm{Fe_3O_4}$. A time delay between the appearance of rock
salt and spinel-exclusive reflections reveals that first, the iron oxide film
grows with $\mathrm{Fe_{1-\delta}O}$ rock salt structure with exclusive
occupation of octahedral lattice sites. When this film is 1.1$\,$nm thick, the
further growth of the iron oxide film proceeds in the inverse spinel structure,
with both octahedral and tetrahedral lattice sites being occupied. In addition,
iron oxide on $\mathrm{SrTiO_3(001)}$ initially grows with none of these
structures. Here, the formation of the rock salt structure starts when the film
is 1.5$\,$nm thick. This is confirmed by tr-HAXPES data obtained during growth
of iron oxide on $\mathrm{SrTiO_3(001)}$, which demonstrate an excess of
$\mathrm{Fe^{2+}}$ cations in growing films thinner than 3.2$\,$nm. This rock
salt phase only appears during growth and vanishes after the supply of the Fe
molecular beam is stopped. Thus, it can be concluded the rock salt structure of
the interlayer is a property of the dynamic growth process. The tr-GISAXS data
link these structural results to an island growth mode of the first 2-3$\,$nm
on both MgO(001) and $\mathrm{SrTiO_3(001)}$ substrates.
We introduce TopoX, a Python software suite that provides reliable and user-friendly building blocks for computing and machine learning on topological domains that extend graphs: hypergraphs, ...simplicial, cellular, path and combinatorial complexes. TopoX consists of three packages: TopoNetX facilitates constructing and computing on these domains, including working with nodes, edges and higher-order cells; TopoEmbedX provides methods to embed topological domains into vector spaces, akin to popular graph-based embedding algorithms such as node2vec; TopoModelx is built on top of PyTorch and offers a comprehensive toolbox of higher-order message passing functions for neural networks on topological domains. The extensively documented and unit-tested source code of TopoX is available under MIT license at https://pyt-team.github.io/.
We investigate the opportunities and challenges of running virtual reality (VR) studies remotely. Today, many consumers own head-mounted displays (HMDs), allowing them to participate in scientific ...studies from their homes using their own equipment. Researchers can benefit from this approach by being able to reach a more diverse study population and to conduct research at times when it is difficult to get people into the lab (cf. the COVID pandemic). We first conducted an online survey (N=227), assessing HMD owners' demographics, their VR setups, and their attitudes towards remote participation. We then identified different approaches to running remote studies and conducted two case studies for an in-depth understanding. We synthesize our findings into a framework for remote VR studies, discuss the strengths and weaknesses of the different approaches, and derive best practices. Our work is valuable for HCI researchers conducting VR studies outside labs.
Virtual Reality opens up new possibilities as it allows to overcome real-life limitations and create novel experiences. While interacting with other people, it is beneficial to share a common view ...point. We modify the virtual world to allow face-to-face interaction with another person, while still retaining an optimal point of view on presented data. This is done by adapting the virtual environment independently for each user, using translation, rotation and scaling. The presented modification of the world gives a natural solution to the problems of collaborative analysis of content. It is therefore beneficial for usage in human-human interaction scenarios that support cooperative work.
