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As part of the NOvA upgrades in 2012, the Recycler was repurposed as a proton stacker for the Main Injector with the aim to deliver 700 kW. Since January 2017, this design power has been run routinely. The steps taken to commission the Recycler and run at 700 kW operationally will be discussed. Major improvements include a new collimation system to control transverse losses and diode damper system to damp the resistive wall instability during slip-stacking. Plans for future running will also be discussed.

From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at ~400 kW beam power. Transmission was very high except for beam lost at or near the 8 GeV injection energy where 95% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the improvements required to achieve high intensity, the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

Two barrier RF systems were fabricated, tested and installed in the Fermilab Main Injector. Each can provide 8 kV rectangular pulses (the RF barriers) at 90 kHz. When a stationary barrier is combined with a moving barrier, injected beams from the Booster can be continuously deflected, folded and stacked in the Main Injector, which leads to doubling of the beam intensity. This paper gives a report on the beam experiment using this novel technology., Comment: 2007 Particle Accelerator Conference (PAC07)

A collimation system has been created for removing proton beam halo in the 8 GeV transfer line from the Fermilab Booster to Main Injector. A pair of 1.14 meter long collimators with 5.08 cm rectangular apertures is installed in a 5-m straight section. Horizontal and vertical motion systems allow them to be positioned such that halo can be scraped from four sides. An additional pair of collimators, placed one cell (90 degrees) downstream, scrape halo which is of opposite phase. Each collimator pair can scrape about 600 Watts of beam power, limited by residual activation of beamline components and sump water outside of the beam line tunnel. Personnel exposure is reduced by surrounding the iron absorber with a layer of marble. Design features, radiation calculations and instrumentation considerations will be described.

A programmable system has been constructed to provide an easy means to display beam intensities and efficiencies from the various Fermilab accelerators. The purpose of these displays is to provide an alternative display method for this information. The system consists of a central microprocessor, a data acquisition subsystem, an interface to the Fermilab control system, and a link driver to drive multiple displays consisting of the name of the parameter being displayed, the units for the parameter displayed, the time the data was taken, and the actual data. The final system will have a display box at each control console in the main control room. >

In this report we present the results of beam dynamics simulations as well as experiments with protons for deceleration from 150 GeV to 8.9 GeV in the Fermilab Main Injector (MI). The simulations are carried out on two different deceleration schemes: deceleration with a fast recovery MI cycle and with a slow recovery cycle. As a proof of principle we have carried out the first successful deceleration using proton beam in the Main Injector from the Tevatron extraction energy of 150 GeV to the Recycler injection energy of 8.9 GeV.

We discuss both simulations as well as experimental studies of a potentially beneficial acceleration scheme in the MI for pbars from the Accumulator Ring or Recycler Ring. The scheme involves accepting the pbar bunches with 2.5 MHz RF structure from either of these two synchrotrons. Re-bunching using the 53 MHz RF system isoadiabatically and accelerating using 53 MHz RF system from 8 GeV to 150 GeV. Further we try to coalesce the beam using the 2.5 MHz RF system. Various stages of RF manipulation are discussed and some improvements are also suggested.