6 Batch Injection and Slipped Beam Tune Measurements in Fermilab's Main Injector

TL;DR

This paper reports measurements of beam tune shifts during batch injection and slip stacking in Fermilab's Main Injector, confirming theoretical predictions and supporting future 12-batch slip stacking operations.

Contribution

It provides experimental validation of tune shifts during slip stacking, demonstrating agreement with linear theory and assessing nonlinear effects.

Findings

Tune shifts due to beam intensity match theoretical predictions.

RF frequency changes cause predictable tune shifts, with some nonlinear effects at large changes.

Results support the feasibility of 12-batch slip stacking in Recycler operations.

Abstract

During Nova operations it is planned to run the Fermilab Recycler in a 12 batch slip stacking mode. In preparation for this, measurements of the tune during a six batch injection and then as the beam is slipped by changing the RF frequency, but without a 7th injection, have been carried out in the Main Injector. The coherent tune shifts due to the changing beam intensity were measured and compared well with the theoretically expected tune shift. The tune shifts due to changing RF frequency, required for slip stacking, also compare well with the linear theory, although some nonlinear affects are apparent at large frequency changes. These results give us confidence that the expected tunes shifts during 12 batch slip stacking Recycler operations can be accommodated.