Date of Award


Document Type


Degree Name

Bachelor of Science




One of the central physics goals of Jefferson Lab is to understand how quarks and gluons form nuclei. The 12 GeV upgrade is nearing completion and a new detector, CLAS12, is being built in Hall B. One of the approved experiments will measure the magnetic form factor of the neutron (Gn ). To make this measurement, the ratio of electron-neutron (e-n) to electron-proton (e-p) scattering events will be extracted from deuterium in quasi-elastic kinematics. A major source of systematic uncertainty is the neutron detection efficiency (NDE) of CLAS12. To better understand the NDE I used the Monte Carlo code gemc to simulate quasi-elastic e-n events like those expected in the Gn experiment. I then analyzed the simulated e-n events by using the measured, scattered electron information to predict the neutron’s path. The neutron is detected in CLAS12’s electromagnetic calorimeter (EC). If the predicted neutron path intersected the fi volume of the EC, then I searched for a hit near that point. The NDE is the ratio of the number of neutrons found in the EC to the number of neutrons predicted to hit the EC. The analysis was done using the newly released CLAS12 reconstruction tools. I observe a rapid rise in the NDE at low neutron momentum and a plateau around 70% at 3GeV with the pre-shower calorimeter (PCAL). This plateau falls to 60% without PCAL.

Included in

Physics Commons