A successful season of beam

Mary Convery

The accelerators have done their job for the year, and on July 7, we shut them down for our annual summer maintenance period. We have met all of this year’s beam delivery goals, including running consistently above 700-kilowatt beam power to the NOvA experiment. Thanks to the Proton Improvement Plan, we have demonstrated the ability to run more than 2×1017 protons per hour in the Booster to support NOvA, the Short-Baseline Neutrino experiments and the new Muon Campus. The Muon Campus beamlines, target systems and power supplies for Muon g-2 were installed and commissioned, delivering billions of muons to the experiment’s storage ring for detector commissioning prior to the shutdown.

A highlight of the Proton Improvement Plan was the success of a new laser notcher in the Linac RFQ injection line, a first-of-its-kind application of lasers. The laser bounces back and forth between mirrors to neutralize the negative-hydrogen ion beam coming out of the source, removing a small section of beam before it is accelerated in the Linac. By the time the beam is accelerated and ready to be extracted from the Booster, the notch created by the laser is lined up with the space needed by the Booster extraction kicker to fire without spraying the beam into nearby components. By creating the notch at low energy in the Linac instead of in the Booster, beam losses in the Booster are significantly reduced. This allows us to run more beam to users.

During the summer shutdown, we will complete the final of three phases of modifications to the Recycler vacuum system. Last year the installation of collimators and the development of a new damper for the Recycler were critical in enabling us to reach 700 kilowatts. This year we will further efforts to reduce and control beam losses by increasing beam apertures. Proton Improvement Plan efforts towards reliability will continue with the installation of two more Marx modulators in the Linac and the completion of 22 RF cavities in the Booster. New septa magnets will be installed in the Delivery Ring to allow beam to Muon g-2 at the full operational repetition rate, and magnets for the future Mu2e beamline will be installed in the tunnel shared by Mu2e and Muon g-2. Countless maintenance jobs will be performed.

As always, we are grateful for the help from other divisions that allows us to accomplish so much.

Mary Convery is the Accelerator Division associate head for accelerator systems.