ANL, Lemont, Illinois, USA
We report on measurements of beams from thermionic cathode (TC) rf guns in the Advanced Photon Source S-Band Linac. These measurements include the macropulse out of both new and existing TC guns as well as the observation of microbunching within the micropulses of these beams. A gun chopper limits the macropulse FWHM duration to the 10-ns range. Our objectives were to analyse the new TC gun and investigate microbunching within a TC-rf-gun-generated beam. Our diagnostics elucidated longitudinal beam structures from the ns to the fs time scales. Coherent transition radiation (CTR) interferometers responding to far-infrared wavelengths were employed after each compression stage to provide the autocorrelations of the sub-ps micropulse durations. The first compression stage is an alpha magnet and the second a chicane. A CCD camera was used to image the beam via optical transition radiation from an Al screen at the end of the linac and also employed to measure coherent optical transition radiation (COTR) in the visible range. The COTR diagnostic observations, implying microbunching on a fs time scale, are presented and compared with a longitudinal space-charge impedance model.
ANL, Lemont, Illinois, USA
A new synchrotron light monitor has been tested for the booster synchrotron of the Advanced Photon Source. Visible light synchrotron radiation is collected by a mirror on a path tangential to the electron beam orbit, and directed to an optical imaging system and camera. This is planned to be a non-intercepting, transverse beam-size monitor even with the higher stored beam charges (~17 nC) needed for the Advanced Photon Source Upgrade. In the present work, we describe the present synchrotron radiation diagnostic layout. An analysis of the synchrotron radiation power on the mirror, the optical layout with components, and features of the control system will be presented.
ANL, Lemont, Illinois, USA
The Linac Extension Area has been developed into a beamline area for testing accelerator components and techniques. Beginning commissioning activities in February 2023, we have delivered the first electron beam to the Linac Extension Area at the Advanced Photon Source at 425 MeV. In the present work, we outline the stages of re-commissioning the electron beamline. We summarise measurements of the electron beam transport through the accelerator. We outline scenarios used to verify the adequacy of radiation shielding of the beamline, and measured shielding performance.