Undergraduate Research at Jefferson Lab

Physics and Technology of EM Calorimeter

Student: Joseph LoPreto

School: James Madison University

Mentored By: Bogdan Wojtsekhowski

A key instrument for the high impact Jefferson Lab experiment investigating the nucleon structure via the study of a proton elastic electric form factor is the electromagnetic calorimeter. An electromagnetic shower calorimeter measures the energy of a particle. This is done by generating a particle shower, which is the result of alternating pair-production and Bremsstrahlung radiation in the detector. The calorimeter proposed to be constructed is composed of lead glass with photomultiplier tubes connected via Borosilicate +33 light guides. The novel approach for electromagnetic calorimetry being developed is based on operating according to a high temperature regime and requires technological advances to resolve two remaining problems with the calorimeter's construction. First, a number of the Borosilicate +33 cylinders have developed strain after being glued to lead-glass. Second, the epoxy attaching the lead-glass and Borosilicate +33, Eccobond F202 Bipax, is extremely difficult to remove. In order to prevent strain from developing in the Borosilicate +33 cylinders, the glass is annealed. In order to disconnect lead-glass and light guides which were improperly adhered, the material is heated to 340°C and a razor blade and hammer are applied to chip off the residual adhesive. The development of these techniques will allow construction of the electromagnetic shower calorimeter to continue more efficiently.