How to express particle momentum in [rad]

[1Keenan]

Hi all,

I need to use the output of a simulation code in another code who accepts totally different format for data.
Now, the file I have has 5 column with positions and momenta of a certain number of particles (momenta are dimensionless - normalized to electron mass times c (light speed) )
The other code wants momenta expressed in [rad] but I don't know how to convert them...
COuld you help me?

Thanks a lot

 

[mfb]

What is a momentum expressed in rad? Is that some angle of the flight direction?
You'll have to check the documentation how that angle and other parameters are defined.

 

[1Keenan]

Documentation is very poor.
Anyway I think I have to evaluate it in this way:

arcosin (ModulusP/py)

 

[Khashishi]

There's not enough information here to be sure, but rad might mean radians, which are used as units of rapidity. http://en.wikipedia.org/wiki/Rapidity

Are you working with highly relativistic particles?

 

[Vanadium 50]

This is not rapidity.

cos^-1(|p|/p_y) is already in rads/ That is, |p|/p_y is already dimensionless.

 

[1Keenan]

This is not rapidity.

cos^-1(|p|/p_y) is already in rads/ That is, |p|/p_y is already dimensionless.

Yes, I think this is the way.
But now I have another problem: 3rd component of momenta is defined as Dp/pn (n = particle numeber).
But it is not very clear in the documentation how Dp is defined.
I think it is the average momentum - pn, but in this way I have an error message saying gamma < 1...

This is making me crazy...