JLab, Newport News, Virginia, USA
Arizona State University, Tempe, USA
MIT, Cambridge, Massachusetts, USA
Hampton University, Hampton, Virginia, USA
Stony Brook University, Stony Brook, USA
SUNY SB, Stony Brook, New York, USA
HZDR, Dresden, Germany
CEA/DRF/IRFU, Gif-sur-Yvette, France
Temple University, Philadelphia, USA
In 2012 Jefferson Laboratory's energy recovery linac (ERL) driven Free Electron Laser successful completed a transmission test in which high current CW beam (4.3 mA at 100 MeV) was transported through a 2 mm aperture for 7 hours with beam losses as low as 3 ppm. The purpose of the run was to mimic an internal gas target for DarkLight* - an experiment designed to search for a dark matter particle. The ERL was not run again until late 2015 for a brief re-commissioning in preparation for the next phase of DarkLight. In the intervening years, the FEL was rebranded as the Low Energy Recirculator Facility (LERF), while organizationally the FEL division was absorbed into the Accelerator division. In 2016 several weeks of operation were allocated to configure the machine for Darklight with the purpose of exercising - for the first time - an internal gas target in an ERL. Despite a number of challenges, including the inability to energy recover, beam was delivered to a target of thickness 1018 cm-2 which represents a 3 order of magnitude increase in thickness from previous internal target experiments. Details of the machine configuration and operational experience will be discussed.
* J. Balewski et al., A Proposal for the DarkLight Experiment at the Jefferson Laboratory Free Electron Laser, May 2012.
