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Regina Caputo | USLHC | USA

View Blog | Read Bio

A day in the life of a proton

Being a member of ATLAS, I’ve spent a fair amount of time in the ATLAS control room. I realized when I was talking with some of my colleagues who work on accelerator operations that I’ve never seen the actual LHC control room.
Yesterday, while at lunch, I asked if my friend if she would give me a tour (since you need  proper access to get in), so I thought I’d share the experience.

Picture taken from Proceedings of ICALEPCS07,Knoxville,Tennessee

Picture taken from Proceedings of ICALEPCS07,Knoxville,Tennessee

The main CERN control room is not just the for LHC, it is the heart and brain of all the accelerators at CERN. It’s brand new facility, completed in 2006 in preparation for the start of the LHC. I had taken an accelerator physics course before, but needless to say, it’s quite an experience to witness it first hand.
Our little proton friends have quite a journey before they make it into our interaction point and get smashed into bits. Here’s how it goes:
There are 4 accelerators that are used to inject the initial beam into the LHC. The magic begins in “Linac 2” (Linac – Linear Accelerator) which creates the protons and then injects them into the Proton Synchrotron Booster (PSB, or “Booster”). This accelerator provides beam to the ISOLDE (Isotope Separator On-Line) experiment. (There are many physics experiments at CERN other than the ones located on the LHC ring). Every 1.2 seconds a decision is made as to where to send the beam. When ISOLDE doesn’t need it, the Booster can inject into the Proton Synchrotron (PS) where is gets accelerated up to 25 GeV. The PS accelerated it’s first protons in 1959 and continues to work to this day. There is a physics complex called the East Area which utilizes this beam when it’s not being sent elsewhere. Once the protons are up to energy, they are injected into the Super Proton Synchrotron (SPS). Off of this ring, CNGS, a fixed target experiment which sends neutrinos off to Gran Sasso, Italy, and the North Area physics facility are located.
Now for the big one. Once the protons are accelerated to 450 GeV, they can then be injected into the main LHC ring. It will take several injections of the SPS to fill the LHC (~2000) which initially will take around 20 min. All of these injections will have to be in phase, and steered properly because losing the beam at this energy isn’t an option.

The CERN Accelerator Complex

The CERN Accelerator Complex

This is my rudimentary understanding of an amazingly complex system, that sometimes as a particle physicist I don’t appreciate enough. So hats off to the accelerator physicists, the next time you run into one buy him or her a drink. 🙂

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