The Bevatron was a particle accelerator — specifically, a weak-focusing synchrotron — at Lawrence Berkeley National Laboratory which began operating in 1954. The antiproton was discovered there in 1955, resulting in the 1959 Nobel Prize in physics for Emilio Segrè and Owen Chamberlain. It accelerated protons into a fixed target, and was named for its ability to impart energies of billions of eV. (This is the reason why it was named Bevatron: Billions of eV Synchrotron.) It was finally decommissioned in 1993, although the building is still present and visible in satellite images at least as late as 2006.

The Bevatron was largely designed to be energetic enough to create antiprotons, and thus test the hypothesis that every particle has a corresponding anti-particle. At the time it was built, there was no known way to confine a particle beam to a narrow aperture, so the beam space was about four square feet in cross section. In order to create antiprotons (mass 938 MeV) in collisions with nucleons in a stationary target while conserving both energy and momentum, a proton beam energy of slightly over 5 GeV is required. The combination of beam aperture and energy required a huge, 10,000 ton iron magnet. The next generation of accelerators used "strong focusing", and required much smaller apertures, and thus much cheaper magnets. The AGS (Alternating Gradient Synchrotron) at Brookhaven was the first next-generation machine, with an aperture roughly an order of magnitude less in both transverse directions, and reaching 30 GeV proton energy, yet with a less massive magnet ring.

In the years following the antiproton discovery, much pioneering work was done here using beams of protons extracted from the accelerator proper, to hit targets and generate secondary beams of elementary particles, not only protons but also neutrons, pions, "strange particles", and many others. These could in turn be passed for further study through various targets and specialized detectors, notably the liquid hydrogen bubble chamber, for which Luis Alvarez received the Nobel Prize in 1968.

http://en.wikipedia.org/wiki/Bevatron

TSL Technical Information - cyclotron hall

See the other side of the Cyclotron

1. External ion injection: The external ion source can be used with axial injection into the cyclotron. An ECR source is used for a wide variety of ions (from alfa particles to Xenon).

2. The Cyclotron: Isochronous cyclotron for all particles except protons above 100 MeV. For protons in the range 100-180 MeV the cyclotron works as a synchrocyclotron. Particles and energies available.

3. Radiofrequency system: (System1 in figure) Two accelerating electrodes each covering an angle from 72 degrees at centre to 42 degrees at max. radius. Possible to use between 12.25 and 24.5 MHz (on the orbit frequency of the ions and on harmonics 2, 3 and 4). Two modes of operation: Fixed frequency (isochronous cyclotron) and Frequency Modulation (synchrocyclotron) Max. accelerating voltage 50 kV in fixed frequency mode and 16 kV when used in FM mode over a frequency band approx. 24-22 MHz. Max. power per system is 140 kW.

4. Vacuum system: Two large diffusion pumps with cryogenic baffles (and one smaller) combined with two cryopanels in the cyclotron chamber, giving a vacuum of approx. 10^-7 mbar without gas load from internal ion source and 10^-6 mbar with internal ion source.

5. QA1 and QA2 (Quadrupole magnets for focussing of the beam)

6. Internal Ion Source: Internal Penning Ionization sources are used for protons and some light ions (deuterons, alfa particles).

7. Sond 1: Measure the beam current.

8. Collimator: Used to reduce the beam size and the beam current.

9. BMA1 This bending magnet can switch the beam between the a-line and the b-line.

Main data of the Gustaf Werner Cyclotron
Single pole with three sectors for vertical focussing
Pole base diameter 2.8 m
Pole gap hill-hill 0.2 m, valley-valley 0.362 m
Magnet yoke (iron) weight 600 tons
Copper coil weight 50 tons, power consumption max. 300 kW
13 sets of radial gradient field correction coils and two sets of harmonic correction coils
Max. average field 1.75 T at a max. useful radius of 1.2 m
Bending limit K= 192 Q²/A MeV
Focussing limit (protons) 100 MeV, avoided by using frequency modulation up to 180 MeV

Beamline drawing

http://www.tsl.uu.se/technical/tt_cychall.html