Demonstration Of Fast, Single-Shot Photocathode QE Mapping Method Using Mla Pattern Beam
- IIT, Chicago
- Argonne
- Beijing U. of Tech.
- Pohang Accelerator Lab.
- NIU, DeKalb
Quantum efficiency (QE) is the chief figure of merit in the characterization of photocathodes. Semiconductor photocathodes, especially when used in high rep-rate photoinjectors, are known to show QE degradation over time and must be replaced. The totalQE is the basic diagnosticwhich is used widely and is easy to obtain. However, a QE map indicating variations of QE across the cathode surface has greater utility. It can quickly diagnose problems of QE inhomogeneity. Most QE mapping techniques require hours to complete and are thus disruptive to a user facility schedule. A fast, single-shot method has been proposed using a micro-lens array (MLA) generated QE map. In this paper we report the implementation of the method at Argonne Wakefield Accelerator facility. A micro-lens array (MLA) is used to project an array of beamlets onto the photocathode. The resulting photoelectron beam in the form of an array of electron beamlets is imaged at a YAG screen. Four synchronized measurements are made and the results used to produce a QE map of the photocathode.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1452805
- Report Number(s):
- FERMILAB-CONF-18-160-AD-APC; 1677251
- Resource Relation:
- Conference: 9th International Particle Accelerator Conference, Vancouver, BC Canada, 04/29-05/04/2018
- Country of Publication:
- United States
- Language:
- English
Similar Records
Transverse-To-Longitudinal Photocathode Distribution Imaging
Mapping photocathode quantum efficiency with ghost imaging