example of Los Alamos PSR: correct the central momentum value

[dtabell]

Protons circulating in the PSR have a kinetic energy of 797 MeV. That corresponds to a p_0*c of 1459.73103979 MeV. FWIW, that value is computed on the basis of the CODATA 2018 value for the proton rest energy. It will differ in the last 3 digits if one is using CODATA 2014.

[dtabell]

In addition, after inserting the correct value for the central momentum, then later, looking at the list of

in the Visualization tab, I see

Have not yet figured out how this value might arise.

[cchall]

@dtabell pCentral of 1.555 is the central beta gamma for the accelerator. elegant normally reports all momenta as betagamma so for electrons pCentral = 1.555 m_e c makes sense. In the case of other particle types you can just ignore the unit field and take beta * gamma.

[dtabell]

Thanks, @cchall. So that's saying that p_central = 1.5557 ... * m_e c. And the PSR protons do indeed have βγ of 1.5557....

Now that elegant is moving towards handling particles besides electrons, we might improve this by deleting the “ m_ec” and changing the label pCentral to βγ_central.