What does A * Gev/c mean?

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In summary, the conversation discusses an upcoming exam on introductory nuclear physics and an article on heavy ion collisions in the SPS accelerator at CERN. It is mentioned that the experiment uses Pb + Pb collisions at 158 A*Gev/c beam momentum, which translates to 158 GeV/c per nucleon. The SPS is also capable of accelerating single protons or nuclei containing Z protons to 400 GeV or 400 GeV per Z respectively. This is due to the fact that in a given magnetic field, the radius of curvature of the orbit of a singly charged particle is the same whether it is by itself or in a nucleus. The conversation also touches on the recent upgrade of the SPS to 450 GeV
  • #1
Waxbear
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I have an exam in introductory nuclear physics coming up in 2 days. I am supposed to present an article which i have already drawn. The article is about heavy ion collisions in the SPS accelerator at CERN. They keep mentioning that the experiment uses Pb + Pb collisions at 158 A*Gev/c beam momentum. Does this mean that i have to divide by the nuclear mass number A, to get the momentum of individual nucleons?
 
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  • #3
Bill_K said:
It means 158 GeV/c per nucleon.

Okay. But according to Cern, the SPS is capable of beam energies of 400 Gev. I guess this is also pr nucleon then?
 
  • #4
In a given magnetic field, the radius of curvature of the orbit of a singly charged particle is the same whether it's by itself or in a nucleus. So from what you say, the SPS can accelerate a single proton to 400 GeV, or a nucleus containing Z protons to 400 GeV per Z. For Pb-209, the ratio Z/A = 82/209 = 0.39, so 400 GeV per Z works out to 158 GeV per A.
 
  • #5
Bill_K said:
In a given magnetic field, the radius of curvature of the orbit of a singly charged particle is the same whether it's by itself or in a nucleus. So from what you say, the SPS can accelerate a single proton to 400 GeV, or a nucleus containing Z protons to 400 GeV per Z. For Pb-209, the ratio Z/A = 82/209 = 0.39, so 400 GeV per Z works out to 158 GeV per A.

Ah, well that certainly explains it. Beautiful how the max energy of the sps works out to be exactly the energy mentioned in the article. Thank you for your help Bill!
 
  • #6
I think your number of 400 GeV is outdated. As preaccelerator for the LHC, the SPS provides proton beams with 450 GeV.

The LHC has a similar ratio for proton proton and lead lead mode: 3.5 TeV protons and 1.38A TeV lead (corresponds to 3.517 TeV per charge) in 2011.
 
  • #7
mfb said:
I think your number of 400 GeV is outdated. As preaccelerator for the LHC, the SPS provides proton beams with 450 GeV.

The LHC has a similar ratio for proton proton and lead lead mode: 3.5 TeV protons and 1.38A TeV lead (corresponds to 3.517 TeV per charge) in 2011.

I think you're right. But i think the SPS was upgraded from 400 Gev to 450 Gev when it was to be used as a pre-accelerator for the LHC. The experiment from my article was done way back in 2000, when the SPS was probably still operating at 400 Gev.
 

1. What is the meaning of A * GeV/c?

A * GeV/c is a unit used in particle physics to measure the momentum of particles. It is a combination of energy (GeV) and speed (c) and is often used to describe the energy and speed of subatomic particles.

2. How is A * GeV/c calculated?

To calculate A * GeV/c, you first need to convert the mass of the particle (in kilograms) to energy (GeV) using Einstein's famous equation, E=mc^2. Then, you divide the energy by the speed of light, c, to get the momentum in units of GeV/c.

3. What is the relationship between momentum and energy in A * GeV/c?

In A * GeV/c, momentum and energy are directly proportional. This means that as the momentum of a particle increases, so does its energy. In fact, the two are related by the speed of light, c, which is a constant.

4. Why is A * GeV/c used in particle physics?

A * GeV/c is used in particle physics because it allows scientists to describe the energy and speed of subatomic particles in a simple and consistent way. It also takes into account the special theory of relativity, which is crucial in understanding the behavior of particles at high speeds.

5. Can A * GeV/c be converted to other units of momentum?

Yes, A * GeV/c can easily be converted to other units of momentum, such as kilogram-meters per second (kg·m/s) or electron volts per speed of light (eV/c). There are many online converters available to make these conversions, but it is important to remember that the value of A * GeV/c will remain the same regardless of the unit used.

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