## Roger Dixon

#### Linear accelerators for injection

One solution to get from our low-energy particle source to a synchrotron is to go through a linear accelerator, or linac, first.

#### Resonant cavities for the acceleration of charged particles

Creating high-energy beams requires accelerator scientists to overcome many subtleties.

#### Phase stability

Here’s an explainer on beam stability during acceleration in a radio-frequency electric field.

#### Accelerator tunes

This diagram shows the so-called tune space for an accelerated particle beam. The colored lines indicate resonances in tune space to be avoided. The dot represents a possible stable area where neither horizontal nor vertical tunes are near a line. In my last column, we concluded that circular accelerators that pass charged particles through a set of accelerating cavities many times is an effective strategy for achieving high energies. However, maintaining a beam while it makes many passes around the…

#### Turning up the energy

Click to view complete cyclotron illustration in Hyperphysics. The particle beam traverses the cyclotron gap starting near the center. It first moves from the bottom electrode to the top. Then the voltage reverses so that the beam can now cross over from the top electrode to the bottom. This pattern continues, and, with the help of a magnetic field, the beam travels in a gradually outward-moving path until it exits the cyclotron. Image: Hyperphysics In my last column we began…

#### Accelerators without batteries

Accelerators use cavities (the structures running through the center of the tunnel) to kick particle beams to higher and higher energies. Photo: Reidar Hahn In my last column I discussed scattering experiments as a major tool for gathering information about our world. I suggested that we could get more detailed information than our light beams, in combination with our eyes, can provide if we devised more powerful beams and detectors. We concluded that providing beam energy by using flashlight batteries…

#### Particle beams and the scattering process

The Main Injector is the flagship accelerator at Fermilab. Over the coming months, this column will review how machines such as this one achieve high-energy particle beams. Photo: Reidar Hahn Much of the information we gather from the physical world comes to us by a scattering process. Scattering occurs when a beam consisting of light or charged particles strikes a target. The incident particle and target can simply recoil from the interaction, or other additional particles can materialize out of…

#### Epilogue

Roger Dixon Roger Dixon, head of the Accelerator Division, wrote this column. With this column I am closing the books on my last 10 years as Accelerator Division head. While I will be staying on in the position until my successor is fully on board, this is my final column for Fermilab Today. It has been quite a ride. For my entire tenure I’ve felt that nothing is beyond the capability of the Accelerator Division. The talent that resides in…

#### Changes in the AD organization

Roger Dixon Roger Dixon, head of the Accelerator Division, wrote this column. When the Tevatron rode off into the sunset on Sept. 30, people around the laboratory wondered what the people working on the Tevatron would be doing in the future. That was not a problem in the Accelerator Division. We had many projects on the books that were hungry for manpower, and we still do. Nevertheless, the shutdown of the Tevatron was a major transition for our division. As…

#### The last lap – Tevatron’s end

Roger Dixon, head of the Accelerator Division, wrote this column. Roger Dixon The end of the Tevatron era is fast approaching. This is a poignant time for me. I became involved with this historic machine before it existed. I was involved with testing magnets in beams and with the beam extraction system used early on to deliver beam to the fixed-target experiments. Even though my role was small I could not help but feel that I was becoming a part…