A Novel Hadronic Calorimeter With A Direct Neutron Readout

A neutron-sensitive sampling calorimeter based on alternating lead absorber and gadolinium-loaded liquid scintillator layers is investigated using detailed Geant4 Monte Carlo simulations.

In addition to the conventional prompt calorimetric signal, the proposed detector records delayed energy from neutron moderation and capture, providing direct information on the neutron component of hadronic showers.

A six-layer Pb/LAB-Gd calorimeter exposed to 10~GeV protons is studied to characterize its neutron response and evaluate its impact on calorimetric performance.

The delayed deposited energy is found to be almost perfectly proportional to the neutron-capture multiplicity, providing a direct calibration of the neutron-sensitive signal.

Event-by-event analyses further reveal a clear relationship between the prompt calorimetric response and the delayed neutron observable, demonstrating that the latter contains substantial information on the invisible hadronic energy.

Exploiting this correlation through a simple nonlinear event-by-event correction improves the prompt-energy resolution from 21.8% to 13.3% without rejecting events.

Furthermore, the analysis of events with similar neutron multiplicities indicates that neutron-production fluctuations constitute a major contribution to the overall hadronic energy resolution.

These results demonstrate the potential of gadolinium-loaded sampling calorimeters to recover part of the invisible hadronic energy and significantly improve hadronic energy reconstruction and energy resolution.