Experimental Demonstration of Colliding-Beam-Lifetime Improvement by Electron Lenses

We report the successful application of space-charge forces of a low-energy electron beam for improvement of particle lifetime determined by beam-beam interaction at a high-energy collider. In our experiments, an electron lens, a novel instrument developed for the beam-beam compensation, was set on a 980-GeV proton bunch at the Fermilab Tevatron proton-antiproton collider. The proton-bunch losses due to its interaction with the antiproton beam were reduced by a factor of 2 when the electron lens was operating. We describe the principle of electron lens operation and present experimental results.

Figure 1

Layout of the Tevatron electron lens.

Figure 2

Vertical betatron tune shift of the 980-GeV proton bunch vs. the peak electron current in the A11 TEL.

Figure 3

Proton-bunch intensity loss rates at the beginning of store #5155 with $L_0=2.5\times {10}^{32}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$.

Figure 4

Intensities of proton bunches #12 and #36 early in store #5119 with $L_0=1.6\times {10}^{32}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$.

Figure 5

Relative improvement of proton-bunch #12 lifetime induced by TEL vs. time in store #5119.