Fermi National Laboratory

Accelerator Report No. 3: Transport Lines

During the shutdown, the Accelerator Update will offer a series on the history and operation of the laboratory's accelerator complex. The transport lines is the third in a series.

The 750 keV transport line is the first of several transport or transfer lines that connect the five Fermi accelerators to each other in this order: Preaccelerator (Preacc) 750 keV transport line Linac 400 MeV transport line Booster 8 GeV Injection line Main Injector (MI) A1 line for antiprotons and the P1 line for protons Tevatron (TeV). Neither the Antiproton Source nor the Recycler machines are considered accelerators, but they do have transfer lines. There is also Switchyard, which transfers beam from MI to the Meson fixed target experiments.

Accelerator Overview

The 750 keV Transport Line

Each Preacc has its own transport line that merges into one line before entering the Linac. Only one Preacc is used at a time.

The Preacc puts out a continuous supply of H- ions. (Don't get confused by the Preacc names, H- and I-, they're just designations.) The ribbon of ions pass through a device called an Electrostatic Chopper that "chops" out a portion (a pulse) of the beam. Think of this as a real ribbon that's being bulled along. The chopper acts like scissors that clips a 42-microsecond length of ribbon off (the pulse) and continues to do this chopping at the frequency Linac uses. Each pulse goes through a Buncher, which forces the pulse into a bunch, and then transfers each bunch, as it comes along, to the Linac. As you can see by the diagram, the H- line is more complicated with quadrupole, dipole, and special bending magnets, but the transfer is the same.

The picture on the right, looking straight on, is a side view of the merged portion of 750 keV transfer lines. If you look from the blue Buncher cavity on the right and follow it to the left, straight across the picture, you'd be heading upstream toward the I- Source, which is located just beyond the yellow 90 magnet. The components on the left side of the picture, which join at the yellow magnet, make up part of the H- line.

The picture on the left shows a view of the 750 keV Transfer line looking, more or less, upstream toward the H- Source. The source is located beyond the magnet draped in yellow lead blankets. The right side of this picture connects with the left side of the upper picture.

The next report covers the Linac.

Accelerator Update Archive

last modified 9/22/2004   email Fermilab