The OPAL Discussion Forum

[Nicole Neveu <nneveu AT hawk.iit.edu>]

Hi Valeria,

Thanks for the info that's really helpful! I am using OPAL-T, and I mostly understand, but have one more question. How do I know/set  the 6D coordinates of the center particle without generating the distribution first? Do I generate the distribution, pick a particle, and restart?

Or does setting ID1 force a particle to exist with those coordinates in the first step? 

Thanks for your help! 

Nicole

On Sep 1, 2017 3:18 AM, "Rizzoglio Valeria (PSI)" <valeria.rizzoglio AT psi.ch> wrote:

Dear Nicole
are you tracking with OPAL-T or OPAL-Cyc?

If OPAL-T, than the structure of the trackOrbit file does not contain ID0 but only ID1 and ID2.
The idea of this file is to store the trajectories of these two particles that the users are free to set.

This means:
1- distribution from the file:
    you can specified the properties of second (ID1) and third (ID2) particle that you are interested in. In your case one could be the particle describing the dispersion function or the center particle.

2- distribution from OPAL generator without specifying ID1 and ID2:
    the trackOrbit file simply contains the trajectories of the particles that have flag ID1 and ID2 but they have no special meaning. They are just random
    particles from the distribution.

3- distribution from OPAL generator specifying ID1 and ID2:

    DISTRIB1: DISTRIBUTION,
    SIGMAX = xxx,     SIGMAPX = xxx,
    SIGMAY = xxx,      SIGMAPY = xxx,
    SIGMAZ = xxx,      SIGMAPZ = xxx,
    CORRX =  xxx,       CORRY = xxx,      CORRZ =  xxx,

    ID1={x,y,z,px,py,pz}, ID2={x,y,z,px,py,pz}

    DISTRIBUTION = GAUSS, INPUTMOUNITS = NONE;

    In this case, the trackOrbit file will contains the trajectories of these two particles that you  
    specified.

I hope this answers to your questions

Valeria

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Da: opal-request AT lists.psi.ch [opal-request AT lists.psi.ch] per conto di Nicole Neveu [nneveu AT hawk.iit.edu]
Inviato: venerdì 1 settembre 2017 9.02
A: opal
Oggetto: [Opal] Particle Trajectory

Hello all, 

I'm using v1.6 to track particles through two bending magnets. I would like some more information on what particles are chosen for record in the X-trackOrbit.dat file.

i.e. the manual on pg 42 says ID0 is center (reference particle?), an ID1 is off center. So two questions: 

1. is ID1 the particle furthest from ID0?

2. My data is labeled ID1 and ID2 (no ID0). 

See attached file. Is ID1 the center in this case? 

Or is there a flag I need to set to get the center particle? 

Thanks,

Nicole