The OPAL Discussion Forum

[Andreas Adelmann <andreas.adelmann AT psi.ch>]

Hello Sookyoung 
> When I was running my short input in single particle mode, I set some of 
> parameters as below referenced by the example which you included.
> 
> -----------------------------------------------------------------------------------
> Edes=1.0E-3;  
> gamma=(Edes+HMMASS)/HMMASS;
> beta=sqrt(1-(1/gamma^2));
> gambet=gamma*beta;
> P0=gamma*beta*HMMASS;
> brho=(HMMASS*1.0E9*gambet) / CLIGHT;
> value, {gamma,brho,Edes,beta,gambit};
> 
> //define beam parameters
> beam1: BEAM, PARTICLE=HMINUS, pc=P0, NPART=1, CHARGE=-1.0, BCURRENT=1.0E-6, 
> BFREQ=83.209;
> -----------------------------------------------------------------------------------
> 
> But I couldn't understand exactly what these are meaning. These are my 
> question list.
> 
> 1. I guess the first parameter defined as "Edes" is the initial energy of 
> my particle but I couldn't be sure. Is it right to set this 1.0E-3 for 1 
> MeV particle?

Yes 


> 2. The parameter "brho" is automatically set as like that? I didn't use it 
> in my input file directly so I am confused it is used inside the code as 
> itself.

This parameter is not used in the OPAL, hence if you do not use the parameter 
in the input file you can delete them.

> 3. When I set "pc" in beam1, should it always have a value same as P0? If 
> not, how can I determine its value?

I do not understand ... you calculate P0 (above) … ?? 

> 
> 4. Firstly, I want to do the simulation with a single particle. In this 
> case, what is the purpose of BCURRENT and BFREQ?

You need to set this because it defines the charge in the beam.

> Also, I use internal ion source for continuous beam (not as a bunched 
> beam), what should be as BCURRENT and BFREQ?

Ok this is an other question and does not arise in the case of the single 
particle mode. Lets discuss the continuous beam when the single particle
model is correct.

Cheers Andreas 





> 
> 
> Thank you for your reply in advance.
> I am looking forward to get comments soon.
> 
> 
> Best regards,
> Sookyoung Jung