Simulation Studies for Electromagnetic Design of INO ICAL Magnet and its Response to Muons

TL;DR

This paper presents electromagnetic simulations of the INO ICAL magnet to optimize its design for better magnetic field uniformity and efficiency, and studies the impact of magnetic fields on muon detection and trajectory resolution.

Contribution

It introduces a new magnet design with improved field uniformity and reduced power consumption, and evaluates its effect on muon detection performance using GEANT4 simulations.

Findings

Better magnetic field uniformity in the iron layer.

Increased energy resolution for muons up to 20 GeV with higher magnetic fields.

Charge identification efficiency exceeds 90 ext{%} for most muon trajectories.

Abstract

The iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) will be used to measure neutrino mass hierarchy. The magnet in the ICAL detector will be used to distinguish the {\mu^-} and {\mu^+} events induced by {\nu_{\mu}} and {\bar{\nu_{\mu}}}, respectively. Due to the importance of the magnet in ICAL, an electromagnetic simulation has been carried out to study the B-field distribution in iron using various designs. The simulation shows better uniformity in the portion of the iron layer between the coils, which is bounded by regions which have lesser field strength as we move to the periphery of the iron layer. The ICAL magnet was configured to have a tiling structure that gave the minimum reluctance path while keeping a reasonably uniform field pattern.This translates into less Ampere-turns needed for generation of the required magnetic field. At low Ampere-turns, a larger fractional area with \vert B \vert \ge 1 Tesla (T) can be obtained by using a soft magnetic material. A study of the effect of the magnetic field on muon trajectories has been carried out using GEANT4. For muons up to 20 GeV, the energy resolution improves as the magnetic field increases from 1.1T to 1.8T. The charge identification efficiency for muons was found to be more than 90\% except for large zenith angles.