# Beam energy calculation?

1. Jun 18, 2007

### colin.mcenroe

Hello all,

I apologize if this is posted in the incorrect forum. I started working on a summer research project today and it is a part of the STAR experiment. Well, I am a fourth year undergrad (though I am slow by one year) and I am really in over my head here. The professor gave me an another fellow undergrad a text called Ultrarelativistic Heavy-Ion Collisions and set us loose with it. He wants us to use it to learn all about kinematics and such, and I am totally lost because this book seems aimed at graduate level students. He gave us three exercises to work out, but neither my associate nor I were able to complete them. I hope this doesn't violate any rules, but I would like your advice on how to tackle the following problem:

For fixed target experiments, given a kinetic energy of the beam, calculate the beam energy and momentum in the laboratory frame, the rapidity covered in the lab, yproj − ytarg, the center-of-mass rapidity, the velocity of the beam in the laboratory frame, √ S, Ecm, pcm, and the velocity of the beam in the center-of-mass frame. Write the expression used to calculate each quantity. Assume pp interactions with a proton mass of 0.938272 GeV. The velocities should be in c = 1 units so that v ≡ β. The values of Eare 10, 100 and 500 MeV, 1, 2, 10, 14, 60, 160 and 200 GeV.

Now I am stuck on the very first calculation, the beam energy and momentum but I am too embarrassed to ask my professor for help on this stuff because he said it would be really easy. Thanks for your advice!

Colin

2. Jun 19, 2007

### Norman

You know the rest mass of the proton, How are Total energy, rest mass and Kinetic Energy related?

This is really elementary stuff and should have been covered in your Modern Physics class... I think you might be over thinking things here.

3. Jun 25, 2007

### colin.mcenroe

Yeah, sorry about that, figured it out the next morning when I went back.