Measurement of the Muon Stopping Power in Lead Tungstate

TL;DR

This study measures muon energy loss in lead tungstate using CMS cosmic ray data, confirming theoretical expectations and providing the first experimental muon critical energy measurement in this material.

Contribution

It presents the first experimental determination of muon critical energy in lead tungstate and validates the calorimeter energy scale at low energies.

Findings

Muon critical energy in lead tungstate is 160+5/-6±8 GeV.

Energy loss measurements agree with theoretical predictions.

Calorimeter energy scale validated down to sub-GeV energies.

Abstract

A large sample of cosmic ray events collected by the CMS detector is exploited to measure the specific energy loss of muons in the lead tungstate of the electromagnetic calorimeter. The measurement spans a momentum range from 5 GeV/c to 1 TeV/c. The results are consistent with the expectations over the entire range. The calorimeter energy scale, set with 120 GeV/c electrons, is validated down to the sub-GeV region using energy deposits, of order 100 MeV, associated with low-momentum muons. The muon critical energy in lead tungstate is measured to be 160+5/-6 plus or minus 8 GeV, in agreement with expectations. This is the first experimental determination of muon critical energy.