The scalers are only read once per second, NOT every physics trigger.
So the beam helicity will be read once per second with the scalers using
an input register; it will also be read with the EPICS data (once per
second, on a start time independent of the scalers, I believe).
Karen
Vitaliy Ziskin wrote:
>
> The line that reads "If (raw->epics[lambda_half:out:read].value > 4.5)" should read "If
> (raw->epics[plateout].value > 4.5) " sorry for this.
> Also, I wanted to say that I'm planning to ultimetly implement this beam helicity bit into
> the scalers so that we have this info on per event basis. Right now it would be on fill
> to fill basis.
>
> Cheers, Vitaliy
>
> Vitaliy Ziskin wrote:
>
> > I have added two "half wave plate plate at the source" epics variables. Their names are
> >
> > are
> >
> > names: in values out values
> >
> > lambda_half:in:read < 0.5 > 4.5
> >
> > lambda_half:out:read > 4.5 < 0.5
> >
> > The "in values" and "out values" are values of these variables when the plate is
> >
> > in or out respectively. As you can guess, the position of this plate determines
> >
> > the helicity of the beam in a particular fill.
> >
> > Thus, when you do analysis you can do the following
> >
> > Int_t plateout = raw->GetEpicsID("lambda_half:out:read");
> > Int_t platein = raw->GetEpicsID("lambda_half:in:read");
> >
> > If (raw->epics[lambda_half:out:read].value > 4.5)
> >
> > fill the ntuple with the the corresponding helicity (we still need to decide)
> >
> > which half wave plate position correspond to which helicity.
> >
> > Let me know if you have any questions.
> >
> > Cheers, Vitaliy
> >
> > P.S. I have removed some of the ABS epics variables from the Epics.map file. Since
> >
> > they are either not used/disconnected or of little interest (for now).
> >
> > P.P.S. I eddited the dump.C file to do the epics variable dump as well.
> >
> > =====================================================================
> > Vitaliy Ziskin Tel: (617)253-9209
> > MIT 26-547 http://www.lns.mit.edu/people/vziskin/
> > 77 Massachusetts Ave
> > Cambridge, Ma
> > 02139
> > ======================================================================
> > "For long you live and high you fly
> > And smiles you'll give and tears you'll cry
> > And all you touch and all you see
> > Is all your life will ever be"--Pink Floyd
>
> --
> =====================================================================
> Vitaliy Ziskin Tel: (617)253-9209
> MIT 26-547 http://www.lns.mit.edu/people/vziskin/
> 77 Massachusetts Ave
> Cambridge, Ma
> 02139
> ======================================================================
> "For long you live and high you fly
> And smiles you'll give and tears you'll cry
> And all you touch and all you see
> Is all your life will ever be"--Pink Floyd
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