Kamran Vaziri and Don Cossairt
In July, members of the Recycler Department/Ecool Group officially confirmed the first observation of electron cooling of relativistic antiprotons. The group saw the first evidence of interactions between an antiproton beam and an electron beam in the Recycler. E-cooling is already a proven method at lower energies and is used at other laboratories. Fermi National Accelerator Lab (Fermilab) is the first lab to demonstrate e-cooling at high energies, operating the electron beam at 4.3 MeV.
In electron cooling, beams of electrons and antiprotons circulate together at the same speed. Mixing the "hotter" antiprotons with the "colder" electrons cools the beam of antiprotons in the same way that hot gas is cooled when it is mixed with cold gas. The e-cooling results in a smaller beam that is easier to manipulate and accelerate. The eventual goal of e-cooling at Fermilab is to do all the final cooling in the Recycler. Currently, antiprotons are produced and cooled by stochastic cooling in Fermilab's Accumulator, but as the number of stored antiprotons increases, the rate of production goes down. Shifting the burden of cooling from the Accumulator to the Recycler leaves the Accumulator essentially empty, and it can collect antiprotons at the highest possible rate. Ultimately, more antiprotons will result in more collisions at the Tevatron.
The NuMI carbon target leak mitigation has been working very well. While this target has been taking as much beam as the accelerators can provide, a new target was tested as part of a main injector particle production (MIPP) experiment at the Meson Center fixed-target area. The MIPP experiment studies particle production from a variety of elements. The MIPP test will supply information about exactly how many pions and kaons are produced in a collision between the proton beam and the carbon NuMI target. The data will help members of the Main Injector Neutrino Oscillation Search (MINOS) Project to calculate the flux of neutrinos passing through their near and far detectors. The other purpose of this test was to check the target for mechanical design and construction flaws.