Magnetic monopole search with the MoEDAL test trapping detector

Akshay Katre,L Bravina,S Kabana,Y Foka

doi:10.1051/epjconf/201612604025

Abstract

IMoEDAL is designed to search for monopoles produced in high-energy Large Hadron Collider (LHC) collisions, based on two complementary techniques: nucleartrack detectors for high-ionisation signatures and other highly ionising avatars of new physics, and trapping volumes for direct magnetic charge measurements with a superconducting magnetometer. The MoEDAL test trapping detector array deployed in 2012, consisting of over 600 aluminium samples, was analysed and found to be consistent with zero trapped magnetic charge. Stopping acceptances are obtained from a simulation of monopole propagation in matter for a range of charges and masses, allowing to set modelindependent and model-dependent limits on monopole production cross sections. Multiples of the fundamental Dirac magnetic charge are probed for the first time at the LHC.

Highlights

Magnetic monopoles were first postulated by Dirac in 1931, who showed that with their existence, electric charge quantisation could be explained as a natural consequence of angular momentum quantisation [1]
Their introduction would add symmetry to Maxwell’s equations of electromagnetism. ’t Hooft and Polyakov, in 1974, independently demonstrated that a Grand Unified Theory (GUT) scheme possesses a monopole solution when a U(1) subgroup of electromagnetism that is embedded into a larger gauge group is spontaneously broken by the Higgs mechanism [2, 3]
Monopole solutions have been proposed to arise within the electroweak theory itself [4], which relies on spontaneous gauge symmetry breaking

Summary

Introduction

Magnetic monopoles were first postulated by Dirac in 1931, who showed that with their existence, electric charge quantisation could be explained as a natural consequence of angular momentum quantisation [1]. Three kinds of techniques are commonly used to search for magnetic monopoles: (1) General-purpose detectors with high ionisation energy loss detection capabilities (e.g. OPAL at LEP [12] and CDF at the Tevatron [13]); (2) dedicated deployment of nuclear-track detectors [14] around the interaction points (e.g. at LEP [15, 16] and at the Tevatron [17]); and (3) the induction technique applied to accelerator and detector material in which monopoles have stopped and remained trapped (e.g. at HERA [18] and at the Tevatron [19, 20]) These searches have excluded the presence of monopoles with charges equal to or above the Dirac charge and masses up to 400 GeV. The MoEDAL experiment near the LHCb interaction point uses a combination of in-flight detection with nucleartrack detectors and re-usable aluminium trapping detectors [24]

Experimental setup

MMT sub-detector system

17 Sep part of Box 3 Box 1 Box 2 sample number

Monopole simulation

Systematics

Results and conclusions