Search for Steady, Modulated, and Variable Cosmic Ray Sources Using Underground Muons in MACRO

TL;DR

This study used the MACRO detector to analyze 38.5 million underground muons, searching for cosmic ray sources and setting upper limits on muon fluxes, while also exploring source variability and modulation.

Contribution

It presents the first all-sky search for pointlike muon sources with a large underground muon dataset and discusses methods for detecting source modulation and variability.

Findings

Muon flux upper limit ~10^-13 cm^-2 s^-1

No significant pointlike sources detected

Methods for identifying modulated and variable sources described

Abstract

Using a sample of 38.5 million underground muons collected by the MACRO detector we have performed an all-sky search for pointlike sources producing excesses of muons above the expected background. The d.c. muon flux upper limit at the Earth coming from selected sources is of the order of 10^-13 cm^-2 s^-1 or less. Futhermore we discuss searches for possible modulated and variable sources of muons using different techniques.