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

TL;DR

This study measures the separation of muon pairs underground at Gran Sasso, providing high-statistics data that tests hadronic interaction models and finds no evidence for anomalous processes.

Contribution

It offers the first high-statistics measurement of muon pair separation at large distances underground, comparing results with Monte Carlo predictions to validate hadronic interaction models.

Findings

Measured muon pair separations up to 70 m

Good agreement with HEMAS Monte Carlo predictions

No evidence for anomalous P_t components in soft collisions

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_t < 1-2GeV/c. The accuracy of the measurement is such that the possible contribution of rare processes, such as mu + N ----> mu + N + mu- + mu+, 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_t components in soft hadron-Nucleus and Nucleus-Nucleus collisions are required by the MACRO experimental data.