Multiple muon measurements with MACRO

The MACRO experiment at Gran Sasso provides means for detailed studies of multiple coincident penetrating cosmic ray muons. In this paper we concentrate on the studies of the ultrahigh energy primary cosmic ray composition using muon bundle multiplicities, muon pair lateral and angular separation distributions.Othe

A Novel Scheme to Search for Fractional Charge Particles in Low Energy Accelerator Experiments

In the Standard Model of particle physics, the quarks and anti-quarks have fractional charge equal to $\pm1/3$ or $\pm2/3$ of the electron's charge. There has been a large number of experiments searching for fractional charge, isolatable, elementary particles using a variety of methods, including $e^+e^-$ collisions using dE/dx ionization energy loss measurements, but no evidence has been found to confirm existence of free fractional charge particles, which leads to the quark confinement theory. In this paper, a proposal to search for this kind particles is presented, which is based on the conservation law of four-momentum. Thanks to the CLEOc and BESIII detectors' large coverage, good particle identification, precision measurements of tracks' momenta and their large recorded data samples, these features make the scheme feasible in practice. The advantage of the scheme is independent of any theoretical models and sensitive for a small fraction of the quarks transitioning to the unconfinement phase from the confinement phase.Comment: 9 page

A MACRO sampler

We present results from approximately 2 years running with the MACRO detector. Most of these data were taken with one of the six supermodules of the final detector in operation. Using a sample of 1.8×106 muons with E≳1.4 TeV we have searched for an excess of muons of celestial origin over cosmic ray background. No evidence for steady point sources was found. The upper limit on the muon flux at 95% CL is typically 2×10−12 cm−2 sec−2. No evidence for time modulated point sources was found. The muon multiplicity distribution favors a ‘‘light’’ composition for cosmic ray primaries with ≊75% protons above ∼103 TeV. We have also searched for neutrino bursts from supernovae in our Galaxy. None were observed during the period Oct. 1989 to Feb. 1992. Our sensitivity to neutrino bursts from collapsing stars extends to ≊60% of the stars in the Galaxy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87712/2/1222_1.pd