Measurement of the Contribution of Neutrons to Hadron Calorimeter Signals

TL;DR

This paper measures how neutrons contribute to signals in a hadron calorimeter by analyzing the time structure of signals, revealing neutron effects mainly from elastic scattering and their spatial dependence.

Contribution

It provides the first detailed measurement of neutron contributions to hadronic calorimeter signals using pulse shape analysis.

Findings

Neutrons contribute via an exponential tail with a 25 ns time constant.

Neutron contribution increases with distance from the shower axis.

Neutrons do not affect Cherenkov signals in the calorimeter.

Abstract

The contributions of neutrons to hadronic signals from the DREAM calorimeter are measured by analyzing the time structure of these signals. The neutrons, which mainly originate from the evaporation stage of nuclear breakup in the hadronic shower development process, contribute through elastic scattering off protons in the plastic scintillating fibers which provide the $dE/dx$ information in this calorimeter. This contribution is characterized by an exponential tail in the pulse shape, with a time constant of $\sim 25$ ns. The relative contribution of neutrons to the signals increases with the distance from the shower axis. As expected, the neutrons do not contribute to the DREAM \v{C}erenkov signals.