Coalescing at 8 GeV in the Fermilab Main Injector

TL;DR

This paper reports on experiments and simulations of coalescing particle bunches at 8 GeV in the Fermilab Main Injector, achieving about 70% efficiency, and discusses methods to improve this for high-intensity beam injection.

Contribution

It presents new experimental data and simulation results on 8 GeV coalescing, demonstrating effective RF reduction techniques and proposing improvements for higher efficiency.

Findings

Achieved approximately 70% coalescing efficiency at 8 GeV.

Found good agreement between experimental data and simulations.

Discussed potential methods to further increase coalescing efficiency.

Abstract

For Project X, it is planned to inject a beam of 3 10**11 particles per bunch into the Main Injector. To prepare for this by studying the effects of higher intensity bunches in the Main Injector it is necessary to perform coalescing at 8 GeV. The results of a series of experiments and simulations of 8 GeV coalescing are presented. To increase the coalescing efficiency adiabatic reduction of the 53 MHz RF is required, resulting in ~70% coalescing efficiency of 5 initial bunches. Data using wall current monitors has been taken to compare previous work and new simulations for 53 MHz RF reduction, bunch rotations and coalescing, good agreement between experiment and simulation was found. Possible schemes to increase the coalescing efficiency and generate even higher intensity bunches are discussed. These require improving the timing resolution of the low level RF and/or tuning the adiabatic voltage reduction of the 53 MHz.