Abstract
The claim of a neutrino velocity different from the speed of the light, made in September 2011 by the Opera experiment, suggested the study of the time delays between TeV underground muons in the Gran Sasso laboratory using the old data of the MACRO experiment, ended in 2000. This study can also give hints on new physics in the particle cascade produced by the interaction of a cosmic ray with the atmosphere.
Highlights
In September 2011 there was a measurement of the speed of neutrino faster than the speed of light by (v−c)/c = 2.48±0.28(stat)±0.30(sys)×10−5 [2]
If the neutrino velocity is different from c the neutrinos in this cascade, should arrive with times different from the times of the muons from the same parent decay, or from another decay, with a time delay that should change according to the neutrino path length which depends on its zenith angle θ
The total charge and the time of occurrence of the signals were measured at the two ends of each counter with two independent systems, the Energy Response Processor (ERP) and the Pulse Height Recorder and Synchronous Encoder (PHRASE)
Summary
The interaction of a primary cosmic ray with the atmosphere produces a cascade with many kind of particles, and in particular neutrinos and muons. Let us assume a hypothetical hadron of mass 100 GeV, produced by an interaction of a proton with center of mass energy 7 TeV (the LHC energy) If this hypothetical hadron interacts or decays after 10 km producing at the end muons, the delay between the underground muon from the massive particle and the muon produced in the primary vertex is of the order of 13 ns. Under Gran Sasso the fraction of multiple muons produced by cosmic rays with center of mass energy ≥ 7 TeV is estimated of the order of 10−3 in MACRO, corresponding to several thousand vol supplement/. A lot of time was needed to convert programs and to find data files, sometimes stored on data tape cassette of old formats, obsolete and not supported by modern computers
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