Measurement Of Muon Flux Research Articles

Electrical resistivity imaging in transmission between surface and underground tunnel for fault characterization

Electrical resistivity images supply information on sub-surface structures and are classically performed to characterize faults geometry. Here we use the presence of a tunnel intersecting a regional fault to inject electrical currents between surface and the tunnel to improve the image resolution at depth. We apply an original methodology for defining the inversion parametrization based on pilot points to better deal with the heterogeneous sounding of the medium. An increased region of high spatial resolution is shown by analysis of point spread functions as well as inversion of synthetics. Such evaluations highlight the advantages of using transmission measurements by transferring a few electrodes from the main profile to increase the sounding depth. Based on the resulting image we propose a revised structure for the medium surrounding the Cernon fault supported by geological observations and muon flux measurements.

Muography sensitivity to hydrogeological rock density perturbation: roles of the absorption and scattering on the muon flux measurement reliability

ABSTRACTTomography using muons is a method to investigate the subsurface density. Muons are particles produced in the atmosphere, and their absorption depends on the quantity of matter they pass through, hence on the rock density and thickness. The Temporal Tomography of rock mass Density using Muons flux Measurement (T2DM2) project aims to characterise the spatial and temporal density variations of the first hundreds of metres of the subsurface. These variations can be induced by water transfer within the critical zone or other thermo‐hydro‐mechanical processes like fracturing. The imaging potential of muography and its application to hydrogeological processes are introduced. Numerical simulations are performed to estimate the significance of the muon flux fluctuations associated to rock density and composition variations for depths ranging from 60 to 1000 m. Particular attention is paid to muon scattering in rocks, which should be taken into account in order to achieve a good spatial and angular resolution.

Measurement of the atmospheric muon flux at 3500 m depth with the NEMO Phase-2 detector

In March 2013, the Nemo Phase-2 tower was successfully deployed at 80 km off-shore Capo Passero (Italy) at 3500 m depth. The tower operated continuously until August 2014. We present the results of the atmospheric muon analysis from the data collected in 411 days of live time. The zenith-angle distribution of atmospheric muons was measured and results compared with Monte Carlo simulations. The associated depth intensity relation was then measured and compared with previous measurements and theoretical predictions.

Cosmic Background Measurements at a Proposed Underground Laboratory by the REGARD Muontomograph

A portable cosmic particle tracking detector has been developed by the REGARD group with angular resolution of 10 mrad. The Close Cathode Chamber-based tracking system is optimized for environmental and geophysical applications with its weight of 15 kg and size of 51 cm × 43 cm × 32 cm. Our aim was to determine the cosmic background at the site of the proposed accelerator and experimental facilities at an approximate 50 meter depth in Felsenkeller, Dresden, Germany. Here, we present our high-precision muon flux measurements, which have been performed during 44 days in one of the tunnels. Angular acceptance of our mapping covered full 2π solid angle of the upper hemisphere. The maximum flux value is found to be below 2.5 m-2sr-1s-1.

Joint measurement of the atmospheric muon flux through the Puy de Dôme volcano with plastic scintillators and Resistive Plate Chambers detectors

AbstractThe muographic imaging of volcanoes relies on the measured transmittance of the atmospheric muon flux through the target. An important bias affecting the result comes from background contamination mimicking a higher transmittance. The MU‐RAY and TOMUVOL collaborations measured independently in 2013 the atmospheric muon flux transmitted through the Puy de Dôme volcano using their early prototype detectors, based on plastic scintillators and on Glass Resistive Plate Chambers, respectively. These detectors had three (MU‐RAY) or four (TOMUVOL) detection layers of 1 m2 each, tens (MU‐RAY) or hundreds (TOMUVOL) of nanosecond time resolution, a few millimeter position resolution, an energy threshold of few hundreds MeV, and no particle identification capabilities. The prototypes were deployed about 1.3 km away from the summit, where they measured, behind rock depths larger than 1000 m, remnant fluxes of 1.83±0.50(syst)±0.07(stat) m−2 d−1 deg−2 (MU‐RAY) and 1.95±0.16(syst)±0.05(stat) m−2 d−1 deg−2 (TOMUVOL), that roughly correspond to the expected flux of high‐energy atmospheric muons crossing 600 meters water equivalent (mwe) at 18° elevation. This implies that imaging depths larger than 500 mwe from 1 km away using such prototype detectors suffer from an overwhelming background. These measurements confirm that a new generation of detectors with higher momentum threshold, time‐of‐flight measurement, and/or particle identification is needed. The MU‐RAY and TOMUVOL collaborations expect shortly to operate improved detectors, suitable for a robust muographic imaging of kilometer‐scale volcanoes.

Cosmic muon flux measurements at the Kimballton Underground Research Facility

In this article, the results from a series of muon flux measurements conducted at the Kimballton Underground Research Facility (KURF), Virginia, United States, are presented. The detector employed for these investigations, is made of plastic scintillator bars readout by wavelength shifting fibers and multianode photomultiplier tubes. Data was taken at several locations inside KURF, spanning rock overburden values from ∼ 200 to 1450 m.w.e. From the extracted muon rates an empirical formula was devised, that estimates the muon flux inside the mine as a function of the overburden. The results are in good agreement with muon flux calculations based on analytical models and MUSIC.

Measurements of the atmospheric muon flux using a mobile detector based on plastic scintillators read-out by optical fibers and PMTs

Precise measurements of the muon flux are important for different practical applications, in environmental studies and for the estimation of the water equivalent depths of underground sites. A first configuration of the mobile detector was composed of two 1 m2 scintillator plates, each viewed by wave length shifters and read out by two PMTs (Photomultiplier Tubes). A more recent configuration of the mobile muon detectors, set up in IFIN-HH, Romania, consists of two 1 m2 detection layers, each one including four 1×0.25 m2 large scintillator plates. The light output in each plate is collected by twelve optical fibers and then read out by one PMT. The calibration has been made by comparing the energy deposit spectrum of minimum ionizing particles with the spectra simulated with the GEANT4 code. The device is used to measure the muon flux on different locations at the surface and underground.

Design Study of an Underground Detector for Measurements of the Differential Muon Flux

Since 2006 an underground laboratory is in operation in Unirea salt mine from Slanic Prahova Romania. A new rotatable detector for measurements of the directional variation of the muon flux has been designed and will be put in operation at the end of 2013. The detector will be used to investigate the possible presence of unknown cavities in the salt ore. Preliminary muon flux measurements performed in the underground of Slanic Prahova salt mine show an important variation of the flux with the thickness of the rock but indicate also that more precise data are necessary. Based on that, a modern detector using 4 layers of plastic scintillators bars has been designed. The detector is installed on a rotatable and mobile frame which allows precise directional measurements of the muon flux on different locations in the mine. In order to investigate the performances of the detector, detailed Monte Carlo simulations have been performed using several codes available on the market. The simulations show that the detector can be used for measurements of the differential flux of cosmic ray muons and for the detection of hidden cavities in the ore.

A Mobile Detector for Muon Measurements Based on Two Different Techniques

Precise measurements of the muon flux are important for different practical applications, both in environmental studies and for the estimation of the water equivalent depths of underground sites. A mobile detector for cosmic muon flux measurements has been set up at IFIN-HH, Romania. The device is used to measure the muon flux on different locations at the surface and underground. Its first configuration, not used in the present, has been composed of two 1 m2scintillator plates, each viewed by wave length shifters and read out by two Photomultiplier Tubes (PMTs). A more recent configuration, consists of two 1 m2detection layers, each one including four 1 · 0,25 m2large scintillator plates. The light output in each plate is collected by twelve optical fibers and then read out by one PMT. Comparative results were obtained with both configurations.

Atmospheric muons: experimental aspects

Abstract. We present a review of atmospheric muon flux and energy spectrum measurements over almost six decades of muon momentum. Sea level and underground/water/ice experiments are considered. Possible sources of systematic errors in the measurements are examined. The characteristics of underground/water muons (muons in bundle, lateral distribution, energy spectrum) are discussed. The connection between the atmospheric muon and neutrino measurements are also reported.

Measurement of integrated flux of cosmic ray muons at sea level using the INO-ICAL prototype detector

The India-based Neutrino Observatory (INO) collaboration is planning to set-up a magnetized Iron-CALorimeter (ICAL) to study atmospheric neutrino oscillations with precise measurements of oscillations parameters. The ICAL uses 50 kton iron as target mass and about 28800 Resistive Plate Chambers (RPC) of 2 m × 2 m in area as active detector elements. As part of its R&D program, a prototype detector stack comprising 12 layers of RPCs of 1 m × 1 m in area has been set-up at Tata Institute of Fundamental Research (TIFR) to study the detector parameters using cosmic ray muons. We present here a study of muon flux measurement at sea level and lower latitude. (Site latitude: 18°54′N, longitude: 72°48′E.)

Deterministic pion and muon transport in Earth’s atmosphere

An accurate understanding of the physical interactions and transport of space radiation is important for safe and efficient space operations. Secondary particles produced by primary particle interactions with intervening materials are an important contribution to radiation risk. Pions are copiously produced in the nuclear interactions typical of space radiations and can therefore be an important contribution to radiation exposure. Charged pions decay almost exclusively to muons. As a consequence, muons must also be considered in space radiation exposure studies. In this work, the NASA space radiation transport code HZETRN has been extended to include the transport of charged pions and muons. The relevant transport equation, solution method, and implemented cross sections are reviewed. Muon production in the Earth’s upper atmosphere is then investigated, and comparisons with recent balloon flight measurements of differential muon flux are presented. Muon production from the updated version of HZETRN is found to match the experimental data well.

A mobile detector for measurements of the atmospheric muon flux in underground sites

Muons comprise an important contribution of the natural radiation dose in air (approx. 30 nSv/h of a total dose rate of 65-130 nSv/h), as well as in underground sites even when the flux and relative contribution are significantly reduced. The flux of the muons observed in underground can be used as an estimator for the depth in mwe (meter water equivalent) of the underground site. The water equivalent depth is an important information to devise physics experiments feasible for a specific site. A mobile detector for performing measurements of the muon's flux was developed in IFIN-HH, Bucharest. Consisting of 2 scintillator plates (approx. 0.9 m2) which measure in coincidence, the detector is installed on a van which facilitates measurements at different locations at surface or underground. The detector was used to determine muon fluxes at different sites in Romania. In particular, data were taken and the values of meter water equivalents were assessed for several locations from the salt mine from Slanic Prahova, Romania. The measurements have been performed in 2 different galleries of the Slanic mine at different depths. In order to test the stability of the method, also measure- ments of the muon flux at surface at different elevations were performed. The results were compared with predictions of Monte-Carlo simulations using the CORSIKA and MUSIC codes.

A mobile detector for measurements of the atmospheric muon flux

Measurements of the underground atmospheric muon flux are important in order to determine accurately the overburden in mwe (meter water equivalent) of an un- derground laboratory for appreciating which kind of exper- iments are feasible for that location. Slanic- Prohava is one of the 7 possible locations for the European large un- derground experiment LAGUNA (Large Apparatus studying Grand Unification and Neutrino Astrophysics). A mobile de- vice consisting of 2 scintillator plates ( 0.9 m 2 , each) one above the other and measuring in coincidence, was set-up for determining the muon flux. The detector it is installed on a van which facilitates measurements on different positions at the surface or in the underground and it is in operation since autumn 2009. The measurements of muon fluxes pre- sented in this contribution have been performed in the under- ground salt mine Slanic-Prahova, Romania, where IFIN-HH has built a low radiation level laboratory, and at the surface on different sites of Romania, at different elevations from 0 m a.s.l up to 655 m a.s.l. Based on our measurements we can say that Slanic site is a feasible location for LAGUNA in Unirea salt mine at a water equivalent depth of 600 mwe. The results have been compared with Monte-Carlo simula- tions performed with the simulation codes CORSIKA and MUSIC.

Atmospheric muon and neutrino fluxes at very high energy

The observation of astrophysical neutrinos requires a detailed understanding of the atmospheric neutrino background. Since neutrinos are produced in meson decays together with a charged lepton, important constraints on this background can be obtained from the measurement of the atmospheric muon flux. Muons, however, can also be produced as μ + μ − pairs by purely electromagnetic processes. We use the Z-moment method to study and compare the contributions to the atmospheric muon and neutrino fluxes from different sources ( π/ K decay, charmed and unflavored hadron decay, and photon conversion into a muon pair). We pay special attention to the contribution from unflavored mesons ( η, η′, ρ ∘, ω and ϕ). These mesons are abundant in air showers, their lifetimes are much shorter than those of charged pions or kaons, and they have decay branching ratios of order 10 −4 into final states containing a muon pair. We show that they may be the dominant source of muons at E μ ≳ 10 3 TeV.

CPviolating lepton asymmetry fromBdecays in supersymmetric grand unified theories

We investigate the effect of the dimuon CP asymmetry from the B decay modes, recently observed at 3.2 sigma deviation from the Standard Model (SM) by the D0 collaboration, in the context of SU(5) and SO(10) GUT models. We exhibit that a large amount of flavor violation between the second and the third generation is generated due to the large neutrino atmospheric mixing angle and this flavor violation can be responsible for the observed large CP asymmetry due to the presence of new phases (not present in the CKM matrix) in the Yukawa couplings. We also study the implication of the parameter space in these GUT models with large CP violating lepton asymmetry for different phenomenologies, e.g., Br(tau -> mu + gamma), Br(B_s -> mu + mu) at the Fermilab, direct detection of dark matter (DM) in the ongoing detectors and measurement of muon flux from solar neutrinos at the IceCube experiment.

Measurement of the atmospheric muon flux with the NEMO Phase-1 detector

The NEMO Collaboration installed and operated an underwater detector including prototypes of the critical elements of a possible underwater km 3 neutrino telescope: a four-floor tower (called Mini-Tower) and a Junction Box. The detector was developed to test some of the main systems of the km 3 detector, including the data transmission, the power distribution, the timing calibration and the acoustic positioning systems as well as to verify the capabilities of a single tridimensional detection structure to reconstruct muon tracks. We present results of the analysis of the data collected with the NEMO Mini-Tower. The position of photomultiplier tubes (PMTs) is determined through the acoustic position system. Signals detected with PMTs are used to reconstruct the tracks of atmospheric muons. The angular distribution of atmospheric muons was measured and results compared to Monte Carlo simulations.

Measurement of the atmospheric muon flux with a 4 GeV threshold in the ANTARES neutrino telescope

A new method for the measurement of the muon flux in the deep-sea ANTARES neutrino telescope and its dependence on the depth is presented. The method is based on the observation of coincidence signals in adjacent storeys of the detector. This yields an energy threshold of about 4 GeV. The main sources of optical background are the decay of 40K and the bioluminescence in the sea water. The 40K background is used to calibrate the efficiency of the photo-multiplier tubes.

Possibility of hgh Z material detection by a setup for natural cosmic-ray muon flux measurement

A design is proposed and a resolving power is calculated for a detector that monitors the unauthorized transportation of high Z materials (nuclear materials with Z > 90) using the natural cosmic-ray muon flux. The identification of nuclear materials is based on the strong dependence of the multiple scattering angle on the matter charge upon traversing the matter by cosmic muons. It is proposed that chambers assembled from drift aluminum tubes similar to chambers used in the muon system of the ATLAS detector be used as the coordinate detector for the setup. The calculations show that the proposed variant of the setup makes it possible to detect the presence of nuclear materials with a weight of about 0.5–1 kg and higher in the inspected volume in a measurement time of several minutes.

Measurement of the cosmic ray and neutrino-induced muon flux at the Sudbury neutrino observatory

Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and un-oscillated portion of the neutrino flux. A total of 514 muon-like events are measured between $-1 \le \cos{\theta}_{\rm zenith} \le 0.4$ in a total exposure of 2.30\times 10^{14}$ cm$^{2}$ s. The measured flux normalization is $1.22 \pm 0.09$ times the Bartol three-dimensional flux prediction. This is the first measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO with zenith angle $\cos{\theta}_{\rm zenith} > 0.4$ is measured to be $(3.31 \pm 0.01 {\rm (stat.)} \pm 0.09 {\rm (sys.)}) \times 10^{-10}~\mu$/s/cm$^{2}$.