Calculation of conventional and prompt lepton fluxes at very high energy

An efficient method for calculating inclusive conventional and prompt atmospheric leptons fluxes is presented. The coupled cascade equations are solved numerically by formulating them as matrix equation. The presented approach is very flexible and allows the use of different hadronic interaction models, realistic parametrizations of the primary cosmic-ray flux and the Earth's atmosphere, and a detailed treatment of particle interactions and decays. The power of the developed method is illustrated by calculating lepton flux predictions for a number of different scenarios.Comment: 8 pages, 10 figures, for Proceedings of the International Symposium for Very-High Energy Cosmic-Ray Interactions (ISVHECRI 2014

The hadronic interaction model SIBYLL 2.3c and Feynman scaling

The Monte Carlo model Sibyll has been designed for efficient simulation of hadronic multiparticle production up to the highest energies as needed for interpreting cosmic ray measurements. For more than 15 years, version 2.1 of Sibyll has been one of the standard models for air shower simulation. Motivated by data of LHC and fixed-target experiments and a better understanding of the phenomenology of hadronic interactions, we have developed an improved version of this model, version 2.3, which has been released in 2016. In this contribution we present a revised version of this model, called Sibyll 2.3c, that is further improved by adjusting particle production spectra to match the expectation of Feynman scaling in the fragmentation region. After a brief introduction to the changes implemented in Sibyll 2.3 and 2.3c with respect to Sibyll 2.1, the current predictions of the model for the depth of shower maximum, the number of muons at ground, and the energy spectrum of muons in extensive air showers are presented.Comment: 35th International Cosmic Ray Conferenc

Hadronic interaction model sibyll 2.3d and extensive air showers

We present a new version of the hadron interaction event generator sibyll. While the core ideas of the model have been preserved, the new version handles the production of baryon pairs and leading particles in a new way. In addition, production of charmed hadrons is included. Updates to the model are informed by high-precision measurements of the total and inelastic cross sections with the forward detectors at the LHC that constrain the extrapolation to ultrahigh energy. Minimum-bias measurements of particle spectra and multiplicities support the tuning of fragmentation parameters. This paper demonstrates the impact of these changes on air-shower observables such as X$_{max}$ and N$_{μ}$, drawing comparisons with other contemporary cosmic-ray interaction models

The hadronic interaction model Sibyll – past, present and future

Sibyll is one of the first microscopic interaction models that was specifically developed for interpreting cosmic ray data. It combines non-perturbative concepts of simulating hadronic particle production with predictions derived from perturbative QCD calculations, focusing on forward particle production of relevance in studying cosmic ray interactions. In this contribution we briefly recall the history of Sibyll and then, in this context, describe improvements made in the different versions of the Sibyll model. The discussion focuses on the basic concepts and ideas of these improvements rather than going into detail or giving a comprehensive description of the models. We also discuss shortcomings, conceptual problems, and uncertainties in modeling hadronic interactions and make some suggestions how to address these open questions in the future.Peer Reviewe

The hadronic interaction model Sibyll 2.3c and muon production in extensive air-showers

One of the applications of the hadronic interaction model Sibyll is the simulation of extensive air showers of ultra-high energy cosmic rays. In recent years it has become more and more clear that simulations do not agree with measurements when it comes to observables related to muons in air showers. We discuss the processes in Sibyll that are directly related to muon production in extensive air showers and describe their relation to shower observables

A state-of-the-art calculation of atmospheric lepton fluxes

Atmospheric leptons are of continuous interest for several scientific communities. At low and intermediate energies, atmospheric neutrinos are the signal for studies of fundamental neutrino properties and at high energies, they constitute the background for the characterization of the features of the astrophysical neutrino flux. We have studied in depth the relation between observable inclusive lepton fluxes/ratios and hadronic interactions by using a novel numerical transport equation solver MCEq. It enables us to characterize, with an unprecedented precision, relevant particle interaction energies, important hadron species, and the secondary particle production phase-space in terms of typical accelerator observables. Based on our findings, we improved existing interaction models S IBYLL and D PMJET and created an efficient scheme to propagate correlated model uncertainties into derived lepton fluxes. We present state-of-the-art calculations of inclusive lepton fluxes and discuss possible directions towards reducing uncertainties below 10%.Peer Reviewe

Statics and dynamics of single DNA molecules confined in nanochannels

The successful design of nanofluidic devices for the manipulation of biopolymers requires an understanding of how the predictions of soft condensed matter physics scale with device dimensions. Here we present measurements of DNA extended in nanochannels and show that below a critical width roughly twice the persistence length there is a crossover in the polymer physics

Metal-to-Metal Distance Modulated Au(I)/Ru(II) Cyclophanyl Complexes : Cooperative Effects in Photoredox Catalysis

The modular synthesis of Au(I)/Ru(II) decorated mono- and heterobimetallic complexes with pi-conjugated [2.2]paracyclophane is described. [2.2]Paracyclophane serves as a rigid spacer which holds the metal centers in precise spatial orientations and allows metal-to-metal distance modulation. A broad set of architectural arrangements of pseudo -geminal, -ortho, -meta, and -para substitution patterns were employed. Metal-to-metal distance modulation of Au(I)/Ru(II) heterobimetallic complexes and the innate transannular pi-communication of the cyclophanyl scaffold provides a promising platform for the investigations of structure-activity relationship and cooperative effects. The Au(I)/Ru(II) heterobimetallic cyclophanyl complexes are stable, easily accessible, and exhibit promising catalytic activity in the visible-light promoted arylative Meyer-Schuster rearrangement.Peer reviewe

On the Hydrogen Oxalate Binding Motifs onto Dinuclear Cu and Ag Metal Phosphine Complexes

We report the binding geometries of the isomers that are formed when the hydrogen oxalate ((CO$_{2}$)$_{2}$H=HO$_{x}$) anion attaches to dinuclear coinage metal phosphine complexes of the form [M$_{1}$M$_{2}$dcpm$_{2}$(HOx)]$^{+}$ with M=Cu, Ag and dcpm=bis(dicyclohexylphosphino)methane, abbreviated [MM]$^{+}$. These structures are established by comparison of isomer-selective experimental vibrational band patterns displayed by the cryogenically cooled and N$_{2}$-tagged cations with DFT calculations of the predicted spectra for various local minima. Two isomeric classes are identified that feature either attachment of the carboxylate oxygen atoms to the two metal centers (end-on docking) or attachment of oxygen atoms on different carbon atoms asymmetrically to the metal ions (side-on docking). Within each class, there are additional isomeric variations according to the orientation of the OH group. This behavior indicates that HOx undergoes strong and directional coordination to [CuCu]$^{+}$ but adopts a more flexible coordination to [AgAg]$^{+}$. Infrared spectra of the bare ions, fragmentation thresholds and ion mobility measurements are reported to explore the behaviors of the complexes at ambient temperature