Search results for "Computational physics"

Measurement of the radiation energy in the radio signal of extensive air showers as a universal estimator of cosmic-ray energy

2016

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8±0.7(stat)±6.7(syst) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principles calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the d…

A fast and efficient modified sectional method for simulating multicomponent collisional kinetics

1999

A fast and efficient method for simulating the evolution of internally mixed multicomponent particle size distributions for aerosol coagulation and droplet coalescence is developed. The technique is based upon a bin-wise sectionalization of the particle mass domain and by imposing the condition of mass conservation for each component. The distribution of each species as a function of the total particle mass is represented in each mass bin as a two-parameter exponential function. Particles of a given mass are assumed to be internally homogeneously mixed. The method is shown to be numerically stable for a wide range of time steps. The numerical solution is compared with both analytical result…

Researches concerning the construction of ultrasonic gas filters

2018

Effect of inter-crystal scatter on estimation methods for random coincidences and subsequent correction.

2008

Random coincidences can contribute substantially to the background in positron emission tomography (PET). Several estimation methods are being used for correcting them. The goal of this study was to investigate the validity of techniques for random coincidence estimation, with various low-energy thresholds (LETs). Simulated singles list-mode data of the MADPET-II small animal PET scanner were used as input. The simulations have been performed using the GATE simulation toolkit. Several sources with different geometries have been employed. We evaluated the number of random events using three methods: delayed window (DW), singles rate (SR) and time histogram fitting (TH). Since the GATE simula…

Shift and scale-invariant correlator using a radially stretched phase-only filter

1995

A radial stretching of the phase only filter depending on the energy angular distribution of the target spectrum is used to perform shift and scale invariant pattern recognition. The complex conjugate of a basic size target Fourier transform and the cumulative energy angular distribution are calculated. Then the radially stretched filter providing the same energy contribution to the correlation peak independent on the target size is prepared and used in a conventional correlator, with spherical-wave illumination. The maximum scale ratio of recognizable objects equals 1:1.5. Computer simulations and experimental results, showing the performance of the filter are presented.

Evaluation of legendre functions of argument greater than one

2019

Abstract In this paper we present an algorithm to evaluate Legendre functions of the first and second kinds (P_v ,Q_v ) for integral and half-integral order and argument greater than one. The code is based on the calculation of the continued fraction for the Q's, the Wronskian relating P's and Q's and the application of forward recurrence relations for the P's and backward recurrence for the Q's. We also show an application of these algorithms to the evaluation of the electrostatic field due to a char... Title of program: DLEGENI, DLEGENS Catalogue Id: ADGO_v1_0 Nature of problem We include two codes in order to evaluate: 1) Legendre functions of half-integral order (subroutine DLEGENS) 2) …

Resolution of singularities for multi-loop integrals

2019

Abstract We report on a program for the numerical evaluation of divergent multi-loop integrals. The program is based on iterated sector decomposition. We improve the original algorithm of Binoth and Heinrich such that the program is guaranteed to terminate. The program can be used to compute numerically the Laurent expansion of divergent multi-loop integrals regulated by dimensional regularisation. The symbolic and the numerical steps of the algorithm are combined into one program. Title of program: sector_decomposition Catalogue Id: AEAG_v1_0 Nature of problem Computation of divergent multi-loop integrals. Versions of this program held in the CPC repository in Mendeley Data AEAG_v1_0; sect…

A code to calculate (high order) Bessel functions based on the continued fractions method

2019

Abstract We have developed a fast code to calculate Bessel functions of integer and fractional order based on the continued fractions method. This algorithm is specially useful in the case of Bessel functions of high order because it does not require any recalculation using normalization relations. Title of program: BESSEL, SPHERICAL Catalogue Id: ACNL_v1_0 Nature of problem We include two codes in order to evaluate: a) Bessel functions of fractional order (Subroutine SPHERICAL) b) Bessel functions of integer order (Subroutine BESSEL) Versions of this program held in the CPC repository in Mendeley Data ACNL_v1_0; BESSEL, SPHERICAL; 10.1016/0010-4655(93)90062-H This program has been imported…

JASP: a program to estimate discovery and exclusion limits in prospective studies of searches

2019

Abstract This program computes the discovery and exclusion limits that can be set in prospective studies of new experiments in the search for new phenomena. It properly takes into account the different outcomes that the experiment can obtain including the possible signal and background fluctuations. The procedure gives in general more conservative limits than those obtained assuming that the experiment will obtain a number of events equal to the expected mean. The difference may be essential in those ... Title of program: JASP Catalogue Id: ADES_v1_0 Nature of problem Estimation of discovery and exclusion limits in prospective studies using Poisson statistics and properly including the expe…

A code to evaluate prolate and oblate spheroidal harmonics

2019

Abstract We present a code to evaluate prolate (P^m _n (x), Q^m _n(x); n ≥ m, x > 1) and oblate (P^m _n (ix), Q^m _n(ix); n ≥ m, x > 0) spheroidal harmonics, that is, spherical harmonics (n and m integers) for real arguments larger than one and for purely imaginary arguments. We start from the known values (in closed form) of P^m _(m+1)and P^m ... Title of program: DPROH, DOBLH Catalogue Id: ADHD_v1_0 Nature of problem We include two codes in order to evaluate: Prolate spheroidal harmonics (subroutine DPROH) Oblate spheroidal harmonics (subroutine DOBLH) The two codes evaluate spheroidal harmonics of the first and second kinds for a given order m, from the lowest (positive) degree (n = m) t…