JM Shielding

MASS = 220 KG

Shielding Specs

Neutrons above 100 KeV in energy cause radiation damage to silicon modules of the inner detector. The typical energy of neutrons from backsplash from the calorimeter is 1 MeV, so the provision of a moderator is important. The TRT radiators, made from polyethylene and polypropylene, form an effective moderator in the barrel region, but there is no such protection for the end-cap region. A 5cm thick disc of polyethylene is therefore attached to the face of the end-cap liquid-argon calorimeter. A separate and thicker piece of polyethylene covers the the region of the forward calorimeter FCAL. It is mounted on the beam pipe to ensure maximum coverage.