Fieldable Muon Spectrometer Using Multi-Layer Pressurized Gas Cherenkov Radiators and Its Applications

Cosmic ray muons have been considered as a non-conventional radiation probe in various applications. To utilize cosmic ray muons in engineering applications, two important quantities, trajectory and momentum, must be known. The muon trajectories are easily reconstructed using two-fold detector arrays with a high spatial resolution. However, precise measurement of muon momentum is difficult to be achieved without deploying large and expensive spectrometers such as solenoid magnets. Here, we propose a new method to estimate muon momentum using multi-layer pressurized gas Cherenkov radiators. This is accurate, portable, compact (< 1m3), and easily coupled with existing muon detectors without the need of bulky magnetic or time-of-flight spectrometers. The results show that not only our new muon spectrometer can measure muon momentum with a resolution of ±0.5 GeV/c in a momentum range of 0.1 to 10.0 GeV/c, but also we can reconstruct cosmic muon spectrum with high accuracy (~90%).

ATMOSPHERIC MUON FLUX AT PEV ENERGIES

In the near future, the energy region above few hundreds of TeV may really be accessible for measurements of the atmospheric muon spectrum with IceCube array. Therefore, one expects that muon flux uncertainties above 50 TeV, related to a poor knowledge of charm production cross-sections and insufficiently examined primary spectra and composition, will be diminished. We give predictions for the very high-energy muon spectrum at sea level, obtained with the three hadronic interaction models, taking into account also the muon contribution due to decays of the charmed hadrons.

COSMIC RAY MUON MEASUREMENT BY L3 SPECTROMETER AT CERN

L3 + C is a branch experiment on L3 magnet spectrometer, which is located on the ring of LEP accelerator at CERN. To take the advantage of L3 muon chambers in its low threshold, wide dynamic range and high resolution, the momentum of cosmic ray muons in the range of 15–2000 GeV/c at a shallow depth of 30 m of molasse can be measured precisely. Since 1998, a scintillator detector system, a new fast trigger and DAQ system, and a small air shower array had been established for study the CR muon events independently. Up to August 2000, 8 billion muons and 25 million air shower events had been recorded. The first results for CR muon spectrum and the charge ratio etc. had been obtained.