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Arguelles Delgado C.A.,Wisconsin IceCube Particle Astrophysics Center | Salvado J.,University of Wisconsin - Madison | Weaver C.N.,Wisconsin IceCube Particle Astrophysics Center
Computer Physics Communications | Year: 2015

Simple Quantum Integro-Differential Solver (SQuIDS) is a C++ code designed to solve semi-analytically the evolution of a set of density matrices and scalar functions. This is done efficiently by expressing all operators in an SU(N) basis. SQuIDS provides a base class from which users can derive new classes to include new non-trivial terms from the right hand sides of density matrix equations. The code was designed in the context of solving neutrino oscillation problems, but can be applied to any problem that involves solving the quantum evolution of a collection of particles with Hilbert space of dimension up to six. Program summary Program title: SQuIDS Catalogue identifier: AEXG-v1-0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEXG-v1-0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU Lesser General Public License, version 3 No. of lines in distributed program, including test data, etc.: 18198 No. of bytes in distributed program, including test data, etc.: 137607 Distribution format: tar.gz Programming language: C++11. Computer: 32- and 64-bit x86. Operating system: Linux, Mac OS X, FreeBSD. RAM: Proportional to the number of nodes, the dimension of the Hilbert space, the number of scalar functions, and the number of density matrices used in the problem. Classification: 11.1. External routines: GNU Scientific Library (http://www.gnu.org/software/gsl/). Nature of problem: Solve the evolution of open quantum systems of Hilbert space dimension N with self interactions and interaction with classical fields. Solution method: The SU(N) algebra is implemented as a C++ object and is embedded into the GSL ordinary differential equation solver. Restrictions: The code is only implemented up to Hilbert spaces of dimension six, but a Mathematica notebook is provided in order to generate higher dimensional solutions. Furthermore, only ordinary differential equation solution methods that require only the first derivative can be used. Running time: Proportional to the number of nodes, the dimension of the Hilbert space, the number of scalar functions, the number of density matrices, and the numerical precision used in the problem. © 2015 Elsevier B.V. Source

Taylor A.M.,Dublin Institute for Advanced Studies | Ahlers M.,Wisconsin IceCube Particle Astrophysics Center | Ahlers M.,University of Wisconsin - Madison | Hooper D.,Fermi National Accelerator Laboratory | Hooper D.,University of Chicago
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Using recent measurements of the spectrum and chemical composition of the highest energy cosmic rays, we consider the sources of these particles. We find that these data strongly prefer models in which the sources of the ultra-high-energy cosmic rays inject predominantly intermediate mass nuclei, with comparatively few protons or heavy nuclei, such as iron or silicon. If the number density of sources per comoving volume does not evolve with redshift, the injected spectrum must be very hard (α≃1) in order to fit the spectrum observed from Earth. Such a hard spectral index would be surprising and difficult to accommodate theoretically. In contrast, much softer spectral indices, consistent with the predictions of Fermi acceleration (α≃2), are favored in models with negative source evolution. With this theoretical bias, these observations thus favor models in which the sources of the highest energy cosmic rays are preferentially located within the low-redshift universe. © 2015 us. © 2015 American Physical Society. American Physical Society. Source

Sandstrom P.,Wisconsin IceCube Particle Astrophysics Center
AIP Conference Proceedings | Year: 2014

The Precision IceCube Next Generation Upgrade (PINGU) will require optical sensors with similar performance as the digital optical modules (DOMs) of IceCube, but implemented in a higher-density array. A new design for the PINGU DOM (PDOM) is being pursued that retains the proven mechanical elements of the IceCube DOM, yet takes advantage of recently commercialized high-speed digitizer technology. The main features of the proposed PDOM electronics are discussed, along with status and plans for development. Proposed modifications to the IceCube string architecture that will accommodate the smaller vertical PDOM spacing are presented. © 2014 AIP Publishing LLC. Source

Kelley J.L.,Wisconsin IceCube Particle Astrophysics Center
AIP Conference Proceedings | Year: 2014

In order to detect cosmic ray air showers and neutrinos, the software data acquisition (DAQ) system of the IceCube Neutrino Observatory forms triggers on patterns of Cherenkov light deposition in the detector based on temporal and/or spatial coincidences. Here we describe the algorithms used for triggering, as well as the fast merging algorithm used to combine the time-ordered hit streams from the optical modules. We also present recently implemented and planned modifications of the DAQ that take advantage of our newly upgraded multi-core computer systems at the South Pole. © 2014 AIP Publishing LLC. Source

Bai Y.,University of Wisconsin - Madison | Salvado J.,University of Wisconsin - Madison | Salvado J.,Wisconsin IceCube Particle Astrophysics Center | Stefanek B.A.,University of Wisconsin - Madison
Journal of Cosmology and Astroparticle Physics | Year: 2015

Although there is overwhelming evidence of dark matter from its gravitational interaction, we still do not know its precise gravitational interaction strength or whether it obeys the equivalence principle. Using the latest available cosmological data and working within the framework of ΛCDM, we first update the measurement of the multiplicative factor of cosmology-relevant Newton's constant over the standard laboratory-based value and find that it is consistent with one. In general relativity, dark matter equivalence principle breaking can be mimicked by a long-range dark matter force mediated by an ultra light scalar field. Using the Planck three year data, we find that the dark matter ''fifth-force'' strength is constrained to be weaker than 10-4 of the gravitational force. We also introduce a phenomenological, post-Newtonian two-fluid description to explicitly break the equivalence principle by introducing a difference between dark matter inertial and gravitational masses. Depending on the decoupling time of the dark matter and ordinary matter fluids, the ratio of the dark matter gravitational mass to inertial mass is constrained to be unity at the 10-6 level. Source

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