Results and Perspectives of the Auger Engineering Radio Array

The Auger Engineering Radio Array (AERA) is an extension of the Pierre Auger Cosmic-Ray Observatory. It is used to detect radio emission from extensive air showers with energies beyond $10^{17}~$eV in the $30 - 80~$MHz frequency band. After three phases of deployment, AERA now consists of more than 150 autonomous radio stations with different spacings, covering an area of about $17~$km$^2$. It is located at the same site as other Auger low-energy detector extensions enabling combinations with various other measurement techniques. The radio array allows different technical schemes to be explored as well as cross-calibration of our measurements with the established baseline detectors of the Auger Observatory. We report on the most recent technological developments and give an overview of the experimental results obtained with AERA. In particular, we will present the measurement of the radiation energy, i.e., the amount of energy that is emitted by the air shower in the form of radio emission, and its dependence on the cosmic-ray energy by comparing with the measurement of the the well-calibrated Auger surface detector. Furthermore, we outline the relevance of this result for the absolute calibration of the energy scale of cosmic-ray observatories.Comment: To be published in the Proceedings of the ARENA2016 conference, Groningen, The Netherland

ARIANNA: Measurement of cosmic rays with a radio neutrino detector in Antarctica

The ARIANNA detector aims to detect neutrinos with energies above \SI{e16}{eV} by instrumenting 0.5 Teratons of ice with a surface array of a thousand independent radio detector stations in Antarctica. The Antarctic ice is transparent to the radio signals caused by the Askaryan effect which allows for a cost-effective instrumentation of large volumes. Several pilot stations are currently operating successfully at the Moore's Bay site (Ross Ice Shelf) and at the South Pole. As the ARIANNA detector stations are positioned at the surface, the more abundant cosmic-ray air showers are also measured and serve as a direct way to prove the capabilities of the detector. We will present measured cosmic rays and will show how the incoming direction, polarization and electric field of the cosmic-ray pulse can be reconstructed from single detector stations comprising 4 upward and 4 downward facing LPDA antennas.Comment: Proceedings of the 8th International Conference on Acoustic and Radio EeV Neutrino Detection Activities, ARENA 201

Acceleration by Strong Interactions

Beyond the attractive strong potential needed for hadronic bound states, strong interactions are predicted to provide repulsive forces depending on the color charges involved. The repulsive interactions could in principle serve for particle acceleration with highest gradients in the order of GeV/fm. Indirect evidence for repulsive interactions have been reported in the context of heavy meson production at colliders. In this contribution, we sketch a thought experiment to directly investigate repulsive strong interactions. For this we prepare two quarks using two simultaneous deep inelastic scattering processes off an iron target. We discuss the principle setup of the experiment and estimate the number of electrons on target required to observe a repulsive effect between the quarks.Comment: 6 pages, 7 figure

Determination of the absolute energy scale of extensive air showers via radio emission: systematic uncertainty of underlying first-principle calculations

Recently, the energy determination of extensive air showers using radio emission has been shown to be both precise and accurate. In particular, radio detection offers the opportunity for an independent measurement of the absolute energy scale of cosmic rays, since the radiation energy (the energy radiated in the form of radio signals) can be predicted using first-principle calculations involving no free parameters, and the measurement of radio waves is not subject to any significant absorption or scattering in the atmosphere. To quantify the uncertainty associated with such an approach, we collate the various contributions to the uncertainty, and we verify the consistency of radiation-energy calculations from microscopic simulation codes by comparing Monte Carlo simulations made with the two codes CoREAS and ZHAireS. We compare a large set of simulations with different primary energies and shower directions and observe differences in the radiation energy prediction for the 30 - 80 MHz band of 5.2 %. This corresponds to an uncertainty of 2.6 % for the determination of the absolute cosmic-ray energy scale. Our result has general validity and can be built upon directly by experimental efforts for the calibration of the cosmic-ray energy scale on the basis of radio emission measurements.Comment: 22 pages, 3 figures, accepted for publication in Astroparticle Physic

Reconstructing the cosmic-ray energy from the radio signal measured in one single station

Short radio pulses can be measured from showers of both high-energy cosmic rays and neutrinos. While commonly several antenna stations are needed to reconstruct the energy of an air shower, we describe a novel method that relies on the radio signal measured in one antenna station only. Exploiting a broad frequency bandwidth of $80-300$ MHz, we obtain a statistical energy resolution of better than 15\% on a realistic Monte Carlo set. This method is both a step towards energy reconstruction from the radio signal of neutrino induced showers, as well as a promising tool for cosmic-ray radio arrays. Especially for hybrid arrays where the air shower geometry is provided by an independent detector, this method provides a precise handle on the energy of the shower even with a sparse array

Modelling uncertainty of the radiation energy emitted by extensive air showers

Recently, the energy determination of extensive air showers using radio emission has been shown to be both precise and accurate. In particular, radio detection offers the opportunity for an independent measurement of the absolute energy of cosmic rays, since the radiation energy (the energy radiated in the form of radio signals) can be predicted using first-principle calculations involving no free parameters, and the measurement of radio waves is not subject to any significant absorption or scattering in the atmosphere. Here, we verify the implementation of radiation-energy calculations from microscopic simulation codes by comparing Monte Carlo simulations made with the two codes CoREAS and ZHAireS. To isolate potential differences in the radio-emission calculation from differences in the air-shower simulation, the simulations are performed with equivalent settings, especially the same model for the hadronic interactions and the description of the atmosphere. Comparing a large set of simulations with different primary energies and shower directions we observe differences amounting to a total of only 3.3 %. This corresponds to an uncertainty of only 1.6 % in the determination of the absolute energy scale and thus opens the potential of using the radiation energy as an accurate calibration method for cosmic ray experiments.Comment: 8 pages, 2 figures, ICRC2017 contributio

Фазогенераторная схема с индуктивно-емкостной связью между контурами

Рассматривается теория фазогенераторной схемы с индуктивно-емкостной связью, образованной взаимной индуктивностью полуобмоток дифференциального проходного вихретокового преобразователя и емкостью конденсатора связи, настроенного в резонанс с эквивалентной взаимной индуктивностью. Дается вывод аналитических выражений для определения рабочей частоты, емкости конденсатора связи, чувствительности фазогенераторной схемы. Теоретические выводы подтверждаются результатами экспериментов

Knowledge practices in design: The role of visual representations as 'epistemic objects'

We use a detailed study of the knowledge work around visual representations to draw attention to the multidimensional nature of `objects'. Objects are variously described in the literatures as relatively stable or in flux; as abstract or concrete; and as used within or across practices. We clarify these dimensions, drawing on and extending the literature on boundary objects, and connecting it with work on epistemic and technical objects. In particular, we highlight the epistemic role of objects, using our observations of knowledge work on an architectural design project to show how, in this setting, visual representations are characterized by a `lack' or incompleteness that precipitates unfolding. The conceptual design of a building involves a wide range of technical, social and aesthetic forms of knowledge that need to be developed and aligned. We explore how visual representations are used, and how these are meaningful to different stakeholders, eliciting their distinct contributions. As the project evolves and the drawings change, new issues and needs for knowledge work arise. These objects have an `unfolding ontology' and are constantly in flux, rather than fully formed. We discuss the implications for wider understandings of objects in organizations and for how knowledge work is achieved in practice

Real-Time Observation of Organic Cation Reorientation in Methylammonium Lead Iodide Perovskites.

The introduction of a mobile and polarized organic moiety as a cation in 3D lead-iodide perovskites brings fascinating optoelectronic properties to these materials. The extent and the time scales of the orientational mobility of the organic cation and the molecular mechanism behind its motion remain unclear, with different experimental and computational approaches providing very different qualitative and quantitative description of the molecular dynamics. Here we use ultrafast 2D vibrational spectroscopy of methylammonium (MA) lead iodide to directly resolve the rotation of the organic cations within the MAPbI3 lattice. Our results reveal two characteristic time constants of motion. Using ab initio molecular dynamics simulations, we identify these as a fast (∼300 fs) "wobbling-in-a-cone" motion around the crystal axis and a relatively slow (∼3 ps) jump-like reorientation of the molecular dipole with respect to the iodide lattice. The observed dynamics are essential for understanding the electronic properties of perovskite materials.This work was supported by The Netherlands Organization for Scientific Research (NWO) through the “Stichting voor Fundamenteel Onderzoek der Materie” (FOM) research program. A.A.B. also acknowledges a VENI grant from the NWO. A.A.B. is currently a Royal Society University Research Fellow. Z.S. and Z.C. acknowledge the ANR-2011-JS09-004-01-PvCoNano project and the EU Marie Curie Career Integration Grant (303824). A.A.B., Z.S., and Z.C. thank Dutch-French Academy for the support through van Gogh grant.This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.jpclett.5b0155