Optimizing a pulsed photocathode system for an electron accelerator

High precision beta decay experiments such as the Nab experiment at Oak Ridge National Laboratory meticulously calibrated detector systems. An electron accelerator is being developed at the Triangle Universities Nuclear Laboratory with a designed operating range from 100 kV to 1 MV to characterize detectors for these experiments. A particular focus of these measurements are bremsstrahlung losses, but because measurable bremsstrahlung occurs in less than 1 percent of events, experimental backgrounds are important in direct measurements of the bremsstrahlung. To reduce backgrounds, a pulsed photocathode assembly is under development, with a target pulse width of 1 ns. The beam pulse structure should improve the rejection of background signals from the collected data, thus improving the overall quality of data produced from this experiment. The array was designed to optimize light transmission throughout the system, therefore optimizing electron production. The array itself consists of a pulsed UV photodiode operating at 286nm, a collimator coupled optical fiber, a collimating 90-degree off-axis elliptical mirror, a nonmagnetic parabolic reflector, and our photocathode, producing the electrons for our accelerator. We describe the development and current status of this system.