Barrier RF stacking at Fermilab

A key issue to upgrade the luminosity of the Tevatron Run2 program and to meet the neutrino requirement of the NuMI experiment at Fermilab is to increase the proton intensity on the target. This paper introduces a new scheme to double the number of protons from the Main Injector (MI) to the pbar production target (Run2) and to the pion production target (NuMI). It is based on the fact that the MI momentum acceptance is about a factor of four larger than the momentum spread of the Booster beam. Two RF barriers - one fixed, another moving - are employed to confine the proton beam. The Booster beams are injected off-momentum into the MI and are continuously reflected and compressed by the two barriers. Calculations and simulations show that this scheme could work provided that the Booster beam momentum spread can be kept under control. Compared with slip stacking, a main advantage of this new method is small beam loading effect thanks to the low peak beam current. The RF barriers can be generated by an inductive device, which uses nanocrystal magnet alloy (Finemet) cores and fast high voltage MOSFET switches. This device has been designed and fabricated by a Fermilab-KEK-Caltech team. The first bench test was successful. Beam experiments are being planned.

Motivation

A major performance parameter of the Fermilab Tevatron collider program Run2 is the total integrated luminosity. The goal is 10–15 fb⁻¹ by 2007. There is also a neutrino program NuMI at Fennilab. It uses the 120-GeV proton beams from the MI to generate high intensity neutrino beams for a long baseline experiment at Soudan, Minnesota. This experiment will start in early 2005.