Continuous multiple injections at the Fermilab Main Injector

Abstract

Instead of slip stacking, an alternate method of doubling the linear intensity of the Fermilab Main Injector is discussed. This method makes use of rf barriers to transfer 12 booster batches from the Fermilab Booster to the Main Injector in 12 consecutive booster cycles, totaling 800 ms. After that, adiabatic capture of the beam into 53 MHz buckets can be accomplished in about 10 ms. Because the beam is debunched during the injection process and no rf voltage is required, the beam loading voltages in the rf cavities are small and can be eliminated by a combination of counterphasing and mechanical shorts.

Adiabatic capture and debunching

“…We want to examine adiabatic capturing of a coasting beam in the Main Injector at injection. Here, we set the criterion that the relative change in bucket height or bucket area should be much slower than the synchrotron frequency ω s /2π, or [1,2] where C is a constant.…”

Double intensity injection for antiproton production

“…As shown in Ref. [2], a rather satisfactory capture can be accomplished from an initial rf voltage V 1 = 20 kV to a final rf voltage V 2 = 500 KV in 10.35 ms with n = 10. The result of the capture is shown in Fig.…”

“…However, for the ease of derivation, we continue to assume a rectangular barrier. It is easy to show that [2] …”

“…In Ref. [2], a method to inject continuously 12 booster batches into the Main Injector is described in detail. The injection will fill 6/7 of the Main Injector with double intensity, for both antiproton production and the Numi neutrino project in Run IIb [3].…”

Space charge effects and coherent stability limits in barrier buckets

“…[13]. Besides the increased transverse space charge limit barrier buckets offer greater flexibility for bunch manipulations compared to conventional rf systems, especially for injection and accumulation (see, e.g., [14]). Recently the application of barrier buckets to future high energy colliders was proposed [15].…”