High statistics measurement of the underground muon pair separation at Gran Sasso

Abstract

We present a measurement of the underground decoherence function using multi-muon events observed in the MACRO detector at Gran Sasso at an average depth of 3800 hg/cm 2 .Muon pair separations up to 70 m have been measured, corresponding to parent mesons with P ⊥ ≤ 1÷2 GeV/c. Improved selection criteria are used to reduce detector effects mainly in the low distance separation region of muon pairs. Special care is given to a new unfolding procedure designed to minimize systematic errors in the numerical algorithm. The accuracy of the measurement is such that the possible contribution of rare processes, such as µ ± + N → µ ± + N + µ + + µ − , can be experimentally studied.The measured decoherence function is compared with the predictions of the hadronic interaction model of the HEMAS Monte Carlo code. Good agreement is obtained. We interpret this agreement to indicate that no anomalous P ⊥ components in soft hadronNucleus and Nucleus-Nucleus collisions are required by the MACRO experimental data.Preliminary comparisons with other Monte Carlo codes point out that the uncertainties associated with the hadronic interaction model may be as large as 20%, depending on the energy. MACRO data can be used as a benchmark for future work on the discrimination of shower models in the primary energy region around and below the knee of the spectrum.

Lateral distribution of muons in IceCube cosmic ray events

“…The MACRO detector has previously measured the lateral separation among muons in air showers for primary energies ranging roughly from 10 4 GeV to 10 6 GeV [12]. Buried under 3.8 km water equivalent of rock, MACRO has a minimum muon energy of about 1.3 TeV.…”

High-energy neutrinos from dark matter particle self-capture within the Sun

“…A similar signal from within the Earth may also be exploited in this regard [5,6,13], and though the terrestrial signal is typically smaller than the solar signal, it is a valuable cross-check [10]. In fact, these signals have already been brought to bear to limit dark matter elastic scattering cross sections with nucleons at interesting levels [14,15,16,17,18].…”

Atmospheric muons: experimental aspects

“…Since secondary particles in hadronic cascades have small transverse momenta p t ( ∼ 300 MeV/c), high energy muons are essentially collimated near the shower axis. Considering a primary nucleon, producing mesons of energy E π,K with transverse momentum p t at a height H prod , the average separation of their daughter high energy muons from the shower axis is given by Ambrosio et al (1999):…”

“…The parametric dependences of K(h 0 , θ) and ν(h 0 , θ) are reported in Becherini et al (2006), as the others below. transverse momentum p t at a height H prod , the average separation of their daughter high energy muons from the shower axis is given by Ambrosio et al (1999):…”