and its relations to diamond radiator R&D for Hall D at Jefferson Lab
Richard Jones, University of Connecticut
Yang Guangliang, University of Glasgow
last updated: August 21, 2006
The Collider/Accelerator group at Brookhaven National Lab is actively working on a new electron source design for high-current applications that combines a conventional laser-driven photocathode with a diamond crystal amplifier. Secondary electrons emitted from the photocathode are accelerated through a several kV potential onto a diamond film of approximately 30 microns thickness. These several-keV electrons scatter inelastically from valence-band electrons in the diamond, exciting many of them into the conduction band. These conduction-band electrons have a negative electro-negativity and so are readily emitted into the vacuum when they diffuse to the surface. Coating the exit surface of the diamond with hydrogen enhances this emission probability. This application of diamond as an amplifier stage in a high-resolution tracking detector has been extensively studied in the context of LHC project RD42. The Brookhaven group, under the leadership of I. Ben-Zvi has applied the same basic idea to increasing the performance of photocathode sources in future high-current accelerators such as the energy-recovery linac (ERL). For recent status reports on this development, see Refs. 2-3.