[G12] electron helicity

[Michael C. Kunkel]

Greetings,

I will try to find a configuration file to look into, but that is about 
all I know what to do.

BR
MK

On 2/19/14 4:54 PM, Jason Bono wrote:
> Hello all,
> As i had mentioned at our meeting, before i had to hang up and run for 
> my life, that I'm looking into the sign of the electron helicity. This 
> info was stored in the HEAD bank under EVTCLASS for other experiments .
> for example one experiment had:
>
> EVTCLAS= 1,2 or 11 for positive helicity.
> and,
> EVTCLAS= 4,5 or 14 for negative helicity.
>
>  From a bosdump over various  g12 runs i see that EVTCLASS=14 for the 
> vast majority of the data.  This could mean one of two things:
>
> 1)  The true electron helicity is overall negative meaning that g12 
> did not collect data with a helicity flip rate during production runs 
> (other experiments did with a rate of 30HZ which give net zero 
> helicity, even for polarized experiments)
> 2) The reliable event by event electron helicity information is 
> actually not stored in the EVTCLASS or the convention is different.
>
> Can anyone verify 1? This would explain why the moller measurements 
> are consistently negative as well.  However it was my understanding 
> that MCC *had* to flip the helicity.
> if 2, Does anyone know where i can learn about the convention used by 
> g12? All i can see from the CLAS online BOS viewer is that 
>  EVTCLASS=1-15 means "Physics Events".
>
> Any input would be appreciated and if i am not clear please ask me to 
> elaborate.
> Regards,
> Jason
>
>
> _______________________________________________
> G12 mailing list
> G12 at jlab.org
> https://mailman.jlab.org/mailman/listinfo/g12

-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/g12/attachments/20140219/1897b18f/attachment.html