Re: mass of thrown particle

[David Lawrence <davidl@jlab.org>]

Hi Mark,

    So far, that is exactly what I do. Using the pion hypothesis is not 
so bad in all cases though. Consider the worst-case scenario of a 1 
GeV/c proton with a beta of ~ 0.7. The TOF calculated will be about 30% 
off. With a 4 ns flight time, this gives an error of 
0.3*4ns*55microns/ns = 66 microns. This is reasonably small compared to 
the 150-200 micron position resolutions expected. Of course, for lower 
momentum protons, it gets worse. Until we get some sort of PID going 
though, I think you're stuck with what you're doing now.

Regards,
-David

Mark M. Ito wrote:
> Folks,
>
> To do the time of flight correction correctly for a trajectory 
> generated from the thrown Monte Carlo parameters, I need the mass of 
> the thrown particle. How do I get that?
>
> For now I will hard-wire it to the pion mass since I know that is what 
> I have thrown when I generated the events.
>
>  -- Mark
>

-- 

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