[Jlabsa_gs] **Reminder** Pizza Seminar - Wednesday, April 17, 2019 - A Message from Lorelei Carlson

Jodi Patient patient at jlab.org
Mon Apr 15 11:15:16 EDT 2019



Jefferson Lab's Graduate Student and Post-Doc Association Wiki:
  https://gspda.jlab.org/wiki/index.php/Main_Page

               Please RSVP to:  patient at jlab.org by COB on April 15, 2019


                                           Wednesday, April 17, 2019

                                                        ***F113***

                                                      12:00-1:00 pm



         "Development of a 300 KV DC High Voltage Photogun and Beam Based Studies of
                                                 Alkali Antimonide Photocathodes"


                                                          Yan Wang

                                                        Jefferson Lab


Abstract:
A compact DC high voltage photogun with inverted-insulator geometry was designed, built, and operated reliably at 300 kV bias voltage using alkali-antimonide photocathodes. This photogun will provide a magnetized electron beam for the future Jefferson Lab Electron-Ion Collider (JLEIC) cooler. This research describes key electrostatic design features of the photogun and evaluates the performance of the in-house fabricated photocathodes and the quality of the electron beams. The thermal emittance of the electron beam was measured with various conditions: different gun bias voltages, different laser spot sizes, and photocathodes with different substrate materials. It has been hypothesized that the photocathode surface roughness affects the quality of the photocathodes and the electron beam produced, which is directly related to the thickness of the antimony layer of the photocathode. This effect was studied experimentally for both the beam emittance and photocathode quantum efficiency lifetime, and the measurements indicate that the beam emittance is largely independent of the antimony layer thickness, and the lifetime benefits from a thick layer. This presentation presents a summary of the good performance of the photogun, a remarkable quantum efficiency lifetime of the photocathodes, and a low emittance of the electron beam.
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