Measurement of the Lifetime of Cosmic Ray Muons

2014

In this experiment, the mean lifetime of cosmic ray muons in their rest frame will be measured. We will obtain an exponential time distribution by measuring the time interval, from the point where the muon enters the detector to the point it decays, for a large number of muon decay events. By calculating the gradient, using curve fitting, of this distribution the mean lifetime of the muon in its rest frame will be determined. Another purpose of this experiment is to acquaint the student with workings of Photomultiplier tubes, scintillators and high-speed electronic modules such as discriminators, logic gates, time-to-amplitude converter, and multi-channel analyzer.

Journal of Physics G: Nuclear and Particle Physics, 2013

The charge ratio of cosmic muons holds important information for both the atmospheric neutrino anomaly and hadronic interaction models. In this paper we measured the muon charge ratio (R μ = N μ + /N μ −) in the cosmic ray flux in the momenta range 0.76-1.60 GeV/c by using a cosmic ray telescope. The delayed coincidence method is used based on the reduced mean lifetime of negative muons due to nuclear capture in matter. The systematic time-dependent effects of the muon charge ratio are considered by grouping the decay data into different time intervals. We compared the experimental data with the predictions of CORSIKA simulations using a high energy interaction model (QGSJET-II) and two low energy interaction models (UrQMD and GHEISHA) in the energy range 10 11-10 16 eV for primary particles. In addition, by considering the muon flux in different zenithal and azimuthal angles, the muon angular distribution is obtained as I(θ) = I(0) cos n θ with average n = 1.91 ± 0.07. Dependence of the muon flux on the azimuth angle (the East-West effect) is also observed, due to the influence of the geomagnetic field in particular on low energy muons.

A : This paper reports the results of an experiment to directly measure the time-resolved scintillation signal from the passage of cosmic-ray muons through liquid argon. Scintillation light from these muons is of value to studies of weakly-interacting particles in neutrino experiments and dark matter searches. The experiment was carried out at the TallBo dewar facility at Fermilab using prototype light guide detectors and electronics developed for the Deep Underground Neutrino Experiment. Two models are presented for the time structure of the scintillation light, a phenomenological model and a composite model. Both models find τ T = 1.52 µs for the decay time constant of the Ar * 2 triplet state. These models also show that the identification of the "early" light fraction in the phenomenological model, F E ≈ 25% of the signal, with the total light from singlet decays is an underestimate. The total fraction of singlet light is F S ≈ 36%, where the increase over F E is from singlet light emitted by the wavelength shifter through processes with long decay constants. The models were further used to compute the experimental particle identification parameter F prompt , the fraction of light coming in a short time window after the trigger compared with the light in the total recorded waveform. The models reproduce quite well the typical experimental value ∼0.3 found by dark matter and double β-decay experiments, which suggests this parameter provides a robust metric for discriminating electrons and muons from more heavily ionizing particles.

This experiment uses an organic plastic scintillator and a timing logic array to determine the lifetime of positive and negative muons, the Fermi coupling constant and provide evidence for special relativity. The lifetime of the positive muon was measured to be (2.14 ± 0.17)µs, in good agreement with accepted literature value of (2.19703 ± 0.00004)µs. The negative muon lifetime was also determined, taking into account the formation of muonic atoms within the scintillator and the non-uniform muon charge ratio at sea level. The lifetime of the negative muon was calculated to be (1.97±0.13)µs. This was found to agree well with the literature values of (2.03 ± 0.01)µs. The Fermi coupling constant was calculated to be (1.19 ± 0.10) × 10 −5 GeV −2 which is in good agreement with the accepted value of (1.1663787 ± 0.0000006) × 10 −5 GeV −2 .

We used a scintillator apparatus to monitor muon decay at sea-level from atmospheric sources. By Accumulating a Poisson distribution of muon decay times and accounting for background events, we obtained the mean muon lifetime to be 2.184 ± 0.030ms from an exponential fit. Comparison to other data sets from groups that used our apparatus in a different location, one year ago, yielded interesting results regarding the systematic and random errors associated with our apparatus.

Modern Physics Letters A, 1996

The muon energy spectra at 0° and 89° have been estimated from the decay of nonprompt and prompt mesons created by the individual elemental primary cosmic ray groups during nucleus-air collisions in the upper atmosphere and the results are found to be fairly comparable with the measured muon fluxes obtained from the direct magnetic spectrograph results in Refs. 2–4, and also from the underground indirect measurements in Refs. 5–10. The muon spectrum derived from the single slope primary nucleon spectrum with a constant spectral index of value −2.73 is only slightly different from the present result for energies below 20 TeV. The present muon spectra at large zenith angle exhibit steeper spectral indices when compared to the expected results obtained from primary elemental groups by Parente et al.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2018

In this work, a portable cosmic-ray telescope was designed, assembled and operated to measure the cosmic-ray induced atmospheric muon flux at ground level. The instrument was entirely characterized and modeled from the point-of-view of detector efficiency, energy detection window and counting rate. Experimental data are reported for the characterization of the muon flux at sea level (43°N of latitude) in terms of vertical muon intensity and zenithal angle dependence.

Astroparticle Physics, 2003

Physical Review D, 1997

In this paper, the first of a two-part work, we present the reconstruction and measurement of muon events detected underground by the MACRO experiment at Gran Sasso (E у 1.3 TeV in atmosphere͒. The main aim of this work is to discuss the muon multiplicity distribution as measured in the detector. The data sample analyzed consists of 4.4ϫ10 6 muon events, of which ϳ 263 000 are multiple muons, corresponding to a total live time of 5850 h. In this sample, the observed multiplicities extend above N ϭ35, with intermuon separations up to 50 m and beyond. Additional complementing measurements, such as the inclusive muon flux, the angular distribution, and the muon separation distribution ͑decoherence͒, are also included. The physical interpretation of the results presented here is reported in the following companion paper.

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