Muon Energy Spectrum Research Articles

Muons in IceCube

The IceCube detector allows for the first time a measurement of atmospheric muon and neutrino energy spectra from tens of GeV up to the PeV range. The lepton flux in the highest energy region depends on both the primary cosmic ray composition around the “knee” and the contribution from prompt decays of mostly charmed hadrons produced in air showers. It is demonstrated here that a direct measurement of the atmospheric muon spectrum in the region above 100 TeV is feasible using data that is already available.

Simulation of muon-induced air showers affecting CMS tracking detectors

We study the propagation of energetic muons produced by ultrahigh energy cosmic rays which could penetrate the cavern of a giant experiment called Compact Muon Solenoid (CMS) at CERN. The present work is based on our previous simulation model proposed in [1]. We have improved this model by (1) eliminating the ambiguity via adding Landau-Pomeranchuk-Migdal effect to the Monte-Carlo code, (2) using different incidence angles of the simulated air showers, (3) defining the actual contents of the CMS cavern concrete. We estimate the energy spectrum of muons produced by air showers of primary protons and photons, which could be detected as a background in the CMS tracking detectors. Our results show that muons produced by air showers within the energy range 1017–1020 eV injected to the CMS site could penetrate the cavern with cutoff energy 36.5 GeV.

MUons from PArametric formulas: A fast GEnerator of atmospheric [formula omitted]-bundles for neutrino telescopes (MUPAGE)

Atmospheric muons play an important role for neutrino telescopes, because they provide the most abundant source of events for real time monitoring, calibration and tests. On the other side, they also represent the major background source. A fast Monte Carlo generator (called MUPAGE) of atmospheric muon bundles for underwater/ice neutrino telescopes is presented here. MUPAGE is based on parametric formulas [Y. Becherini, A. Margiotta, M. Sioli, M. Spurio, Astrop. Phys. 25 (2006) 1–13; M. Spurio, Nucl. Instr. and Meth. A 567 (2006) 492] obtained from a full Monte Carlo simulation of cosmic ray showers generating muons in bundles, which are propagated down to 5 km w.e. It produces the event kinematics on the surface of a user-defined virtual cylinder, surrounding the detector. The multiplicity of the muons in the bundle, the muon lateral distribution and energy spectrum are simulated according to a specific model of the primary cosmic ray flux, with constraints from measurements of the muon flux obtained in underground experiments. Some examples of application are presented.

Atmospheric MUons from PArametric formulas: a fast GEnerator for neutrino telescopes (MUPAGE)

Neutrino telescopes will open, in the next years, new opportunities in observational high energy astrophysics. In these detectors, atmospheric muons from primary cosmic ray interactions in the atmosphere play an important role, because they provide the most abundant source of events for calibration and test. On the other side, they represent the major background source. In this paper a fast Monte Carlo generator (called MUPAGE) of bundles of atmospheric muons for underwater/ice neutrino telescopes is presented. MUPAGE is based on parametric formulas [Y. Becherini, A. Margiotta, M. Sioli, M. Spurio, Astrop. Phys. 25 (2006) 1] obtained from a full Monte Carlo simulation of cosmic ray showers generating muons in bundle, which are propagated down to 5 km w.e. It produces the event kinematics on the surface of a user-defined cylinder, surrounding the virtual detector. The multiplicity of the muons in the bundle, the muon lateral distribution and energy spectrum are simulated according to a specific model of primary cosmic ray flux, with constraints from measurements of the muon flux with underground experiments. As an example of application, the result of the generation of events on a cylindrical surface of ∼1.4 km 2 at a depth of 2450 m of water is presented. Program summary Program title: MUPAGE Catalogue identifier: AEBT_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEBT_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3534 No. of bytes in distributed program, including test data, etc.: 61 383 Distribution format: tar.gz Programming language: C++ Computer: Pentium M, 2.0 GHz; 2x Intel Xeon Quad Core, 2.33 GHz Operating system: Scientific Linux 3.x; Scientific Linux 4.x; Slackware 12.0.0 RAM: 50 MB Word size: 32 bits Classification: 1.1, 11.3 External routines: The ROOT system ( http://root.cern.ch) Nature of problem: Fast simulation of atmospheric muon bundles for underwater/ice neutrino telescopes. Solution method: Atmospheric muon events are generated according to parametric formulas [1] giving the flux, the multiplicity, the radial distribution and the energy spectrum. Restrictions: Water vertical depth range from 1.5 to 5 km w.e.; zenith angle range from 0 to 85 degrees. Additional comments: The program requires the ROOT libraries for the pseudorandom number generator.

Neutrino signals from solar neutralino annihilations in anomaly mediated supersymmetry breaking model

The lightest neutralino, as the dark matter candidate, can be gravitationally captured by the Sun. In this paper, we studied the high energy neutrino signals from solar neutralino annihilations in the core of the Sun in the anomaly mediated supersymmetry breaking (AMSB) model. Based on the event-by-event Monte Carlo simulation code WimpSim, we studied the detailed energy and angular spectrum of the final muons at large neutrino telescope IceCube. More precisely, we simulated the processes since the production of neutrino via neutralino annihilation in the core of the Sun, neutrino propagation from the Sun to the Earth, as well as the converting processes from neutrino to muon. Our results showed that in the AMSB model it is possible to observe the energetic muons at IceCube, provided that the lightest neutralino has a relatively large Higgsino component, as a rule of thumb ${N}_{13}^{2}+{N}_{14}^{2}>4%$, or equivalently, ${\ensuremath{\sigma}}_{\mathrm{SD}}>{10}^{\ensuremath{-}5}\text{ }\text{ }\mathrm{pb}$. Especially, for our favorable parameters the signal annual events can reach 102, and the statistical significance can reach more than 20. We pointed out that the energy spectrum of muons may be used to distinguish among the AMSB model and other supersymmetry breaking scenarios.

Energy spectrum of muon in EAS

The compact extensive air shower (EAS) array which consists of 8 scintillation counters, and the solid iron magnet spectrometer (the Okayama muon telescope) have been used to measure energy spectrum of muons in EAS from January 2004 in Okayama University. We compared the result of the muon energy spectrum tagged by EAS trigger signals with EAS simulations which agreed with higher energy hadronic interaction models such as QGSJET and SYBILL, and lower energy hadronic ones such as Hillas Splitting Algorithm, GHEISHA and UrQMD, in order to verify the influence of the hadronic interaction model upon properties of EAS particles, especially the energy spectrum of muons.

Meson cascade in the atmosphere, uncertainties in calculating the fluxes of high-energy muons, and data of direct measurements

A new calculation of the atmospheric fluxes of cosmic-ray hadrons and muons in the energy range 10–104 GeV is performed on the basis of the method for solving nuclear-cascade equations with allowance for a nonscaling behavior of inclusive hadron-production cross sections, the growth of cross sections for inelastic hadron-nucleus collisions with increasing energy, and a non-power-law character of the primary spectrum. The fluxes of secondary cosmic rays at various levels in the atmosphere are calculated for three models of the spectrum and composition of primary cosmic rays. The effect of uncertainties in the spectrumand composition of primary cosmic rays on the flux of atmosphericmuons and their charge ratio at sea level is investigated. The calculated energy spectra of muons at sea level are compared with the results of previous experiments and the results of recent measurements performed by means of the L3 + Cosmic and CosmoALEPH spectrometers, as well as with the results of other calculations.

MACRO constraints on violation of Lorentz invariance

The energy spectrum of neutrino-induced upward-going muons in MACRO has been analysed in terms of relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of $\nu_{\mu} \to \nu_{\tau}$ transitions. The data disfavor these exotic possibilities even at a sub-dominant level, and stringent 90% C.L. limits are placed on the Lorentz invariance violation parameter $|\Delta v| < 6 \times 10^{-24}$ at $\sin 2{\theta}_v$ = 0 and $|\Delta v| < 2.5 \div 5 \times 10^{-26}$ at $\sin 2{\theta}_v$ = $\pm$1. These limits can also be re-interpreted as upper bounds on the parameters describing violation of the Equivalence Principle.

Search for exotic contributions to atmospheric neutrino oscillations

The energy spectrum of neutrino-induced upward-going muons in MACRO was analysed in terms of relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant effect. The data disfavor these possibilities even at a sub-dominant level; stringent 90% C.L. limits are placed on the Lorentz invariance violation parameter $|\Delta v| < 6 \times 10^{-24}$ at $\sin 2{\theta}_v$ = 0 and $|\Delta v| < 2.5 \div 5 \times 10^{-26}$ at $\sin 2{\theta}_v$ = $\pm$1. The limits can be re-interpreted as bounds on the Equivalence Principle violation parameters.

Search for a Lorentz invariance violation contribution in atmospheric neutrino oscillations using MACRO data

The energy spectrum of neutrino-induced upward-going muons in MACRO was analysed in terms of special relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of νµ ↔ ντ transitions. The data disfavour these exotic possibilities even at a sub-dominant level, and stringent 90% C.L. limits are placed on the Lorentz invariance violation parameters. These limits can also be re-interpreted as upper bounds on the parameters describing violation of the Equivalence Principle.

A parameterisation of the flux and energy spectrum of single and multiple muons in the deep water or ice

Atmospheric muons play an important role in underwater/ice neutrino detectors. A parameterisation of the flux of single and multiple muon events, of their lateral distribution and energy spectrum is presented. The kinematics parameters were modelled starting from a full Monte Carlo simulation of the interaction of primary cosmic rays with atmospheric nuclei. The parametric formulas are valid for a vertical depth of 1.5–5km w.e. and up to 85∘ for the zenith angle, and can be used as input for a fast simulation of atmospheric muons in underwater/ice detectors.

A parameterisation of single and multiple muons in the deep water or ice

A new parameterisation of atmospheric muons deep underwater (or ice) is presented. It takes into account the simultaneous arrival of muons in bundle giving the multiplicity of the events and the muon energy spectrum as a function of their lateral distribution in a shower.

Low energy muons in the cosmic radiation

A review of measurements of the muon energy spectra for different altitudes, height and directions performed with devices placed at various geomagnetic latitudes is presented. The muon spectra and the muon charge ratio, defined as the ratio of positive to negative muon fluxes, are analysed taking into account the geomagnetic field, in view of the East-West effect. Fluxes of both positive and negative muons are analysed.

Search for a Lorentz invariance violation contribution in atmospheric neutrino oscillations using MACRO data

The energy spectrum of neutrino-induced upward-going muons in MACRO has been analysed in terms of relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of νμ→ντ transitions. The data disfavor these exotic possibilities even at a subdominant level, and stringent 90% C.L. limits are placed on the Lorentz invariance violation parameter |Δv|<6×10−24 at sin2θv=0 and |Δv|<2.5–5×10−26 at sin2θv=±1. These limits can also be re-interpreted as upper bounds on the parameters describing violation of the equivalence principle.

Measurement of the μ decay spectrum with the ICARUS liquid Argon TPC

Examples are given which prove the ICARUS detector quality through relevant physics measurements. We study the muon decay energy spectrum from a sample of stopping muon events acquired during the test run of the ICARUS T600 detector. This detector allows the spatial reconstruction of the events with fine granularity, hence, the precise measurement of the range and dE/dx of the muon with high sampling rate. This information is used to compute the calibration factors needed for the full calorimetric reconstruction of the events. The Michel rho parameter is then measured by comparison of the experimental and Monte Carlo simulated muon decay spectra, obtaining rho = 0.72 +/- 0.06(stat.) +/- 0.08(syst.). The energy resolution for electrons below ~50 MeV is finally extracted from the simulated sample, obtaining (Emeas-Emc)/Emc = 11%/sqrt(E[MeV]) + 2%.

Muon spectra of quasi-elastic and 1-pion production events in LBL neutrino oscillation experiments

The muon energy spectra of the quasi-elastic and 1-pion production events in a LBL experiment, like K2K, are predicted to follow closely the neutrino energy spectrum, with downward shifts of the energy scale by $<Q^2>/2 M$ and $(<Q^2> + M_\Delta^2 - M^2)/2 M$ respectively. These predictions seem to agree with the observed muon spectra in the K2K nearby detector. The corresponding muon spectra in the far-away (SK) detector are predicted to show characteristic spectral distortions induced by $\nu_\mu$ oscillation. Comparison of the predicted spectral distortions with the observed muon spectra of the 1-Ring and 2-Ring muon events in the SK detector will help to determine the oscillation parameters. The results will be applicable to other LBL experiments as well.

Electron and muon densities in cosmic rays measured at L 3+C

The L 3+C experiment at CERN has been extended with an air shower scintillator array. The combination of the measurement of the shower particle density with the precision measurement of cosmic ray muons in the L 3 spectrometer provides a new tool to study the physics of cosmic rays. Correlations between the electron-photon and the muon components of air showers observed with large area detectors are known to provide information about the composition of the primary cosmic ray flux. For this, new observations on the energy spectrum of muons over a large energy range and the multiplicity distribution of high energy muons are needed. We present here the details of the L 3+C experiment relevant for such studies and discuss some preliminary observations.

Muon density spectra as a probe of the muon component predicted by air shower simulations

The KASCADE experiment measures local muon densities of air-showers in the knee region at various core distances for two different muon energy thresholds. Muon density spectra have been reconstructed for the total EAS sample, as well as for particular subsamples with enhanced light and heavy induced EAS, classified on the basis of the shower size ratio N μ/N e . By comparing these spectra for different muon energy detection thresholds and core distances with detailed Monte Carlo simulations each spectrum should result in the same primary energy spectrum. This allows a comprehensive test of the simulation procedures of the muon lateral distribution and the muon energy spectrum by various Monte Carlo codes. Different combinations of high-energy and low-energy interaction models in the frame of the CORSIKA code are used for comparisons.

Zenith angle distributions of cosmic ray muons

A review of measurements of the muon energy spectra for different altitudes, height and directions performed with devices placed at various geomagnetic latitudes is presented. In addition experimental data for angular distributions from underground laboratories are included. The idea of the present report is to explore whether serious sercrepancies exist among the various values and to give as far as possible a coherent view of the present muon zenith angle distributions knowledge. The fit to all the experimental muon data is presented.

Energy spectra of atmospheric muons measured with the CAPRICE98 balloon experiment

The measurement of the atmospheric muon spectrum is currently of great interest because of the study of atmospheric neutrinos and the claim of neutrino oscillations made in 1998 by the Super-Kamiokande Collaboration. A measurement of the muon flux is an indirect measure of the neutrino flux. Therefore, it can be used to improve the calculation of the atmospheric neutrino flux, which in turn can be compared with the observed neutrino rates in underground detectors. This article reports a new measurement of the m 1 and m 2 spectra at several atmospheric depths in the momentum ranges 0.3‐20 GeV/c and 0.3‐40 GeV/c, respectively. The data were collected by the balloon-borne experiment CAPRICE98 during the ascent of the payload on 28 May 1998 from Fort Sumner, N. M. The experiment used the NMSU-WIZARD/CAPRICE 98 balloon-borne magnet spectrometer equipped with a gas ring imaging Cherenkov detector and a silicon-tungsten calorimeter.