Fermilab main injector: High intensity operation and beam loss control

Abstract

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.

Integrable RCS as a proposed replacement for Fermilab Booster

“…For this exercise, we consider an iRCS with the same aperture and circumference as the Fermilab Booster, that the iRCS has a 20-Hz ramp rate, and that there is no slip-stacking in the Fermilab Recycler or Main Injector. Slip-stacking is an accumulation process that doubles the intensity of the Fermilab Main Injector, but the feasibility of slip-stacking beyond the PIP-II era is still under investigation [13,14]. If 20-Hz slip-stacking can be sustained in the Main Injector or Recycler, the 120-GeV beam power would increase by a factor of 1.5 or 2, respectively.…”

Dynamical stability of slip-stacking particles

“…In application, lost particles migrate to an incorrect azimuthal location and consequently collide into the beam pipe during injection, extraction, or acceleration [4]. We map the stability of initial particle positions by integrating the equations of motion for each position.…”

“…The two beams injected on separated portions of azimuth with a small frequency difference will overlap gradually, allowing injection [4]. When the cyclic accelerator is filled, the azimuthal distribution of the beams will coincide at a certain tune and can then be accelerated simultaneously.…”

“…Particle loss in the slipstacking process is a limiting factor on ultimate performance [1,4]. Single-particle dynamics associated with slip-stacking contribute directly to the particle losses.…”

“…The slipping of bunched beams was first demonstrated at the CERN Super Proton Synchrotron (SPS) [6] but the emittance growth led to unacceptable particle losses. Fermilab has subsequently implemented slip stacking operationally since 2004 [4,7,8]. Initially, the higher beam intensity was used to increase antiproton production for proton-antiproton collider experiments [9].…”