[Halld-offline] Beam Polarization

[Justin Stevens]

It seems the simplest place to include this in our current framework is the CCDB, assuming the polarization is not varying much within a single run or range of runs.  For the energy dependence of the polarization, we could store

1) a table with polarization values for individual energy bins (eg. tagger counters/columns) or
2) some parameters for a function which describes the polarization shape with energy

The polarization direction for a run should already be in RCDB, but probably should be mirrored in CCDB for simplicity.

-Justin

On Feb 22, 2016, at 8:50 PM, Paul Mattione wrote:

> Well, if we were to fit the polarization many different times within a run, we would need a mechanism for storing, and then looking up, the fit results relevant for each given range of events.  Do we have a mechanism that can do this yet?  Or am I thinking about this wrong? 
> 
>  - Paul
> 
> On Feb 22, 2016, at 8:30 PM, Curtis A. Meyer <cmeyer at cmu.edu> wrote:
> 
>> Yes, but it does depend on the photon energy. E.g. how far away from the coherent edge are you?
>> Events near the edge will have the highest degree of linear polarization, while those far away will
>> have less. If the edge is stable, the function is pretty simple., but we still need to be able to assign
>> both a polarization and a polarization direction to our photons on an event-by -event basis.
>> 
>> Curtis
>> ---------
>> Curtis A. Meyer			MCS Associate Dean for Faculty and Graduate Affairs
>> Wean:    (412) 268-2745	Professor of Physics
>> Doherty: (412) 268-3090	Carnegie Mellon University
>> Fax:         (412) 681-0648	Pittsburgh, PA 15213
>> curtis.meyer at cmu.edu	http://www.curtismeyer.com/
>> 
>> 
>> 
>>> On Feb 22, 2016, at 8:25 PM, Paul Mattione <pmatt at jlab.org> wrote:
>>> 
>>> I was under the impression that, for a given beam energy, the polarization would be relatively constant over the course of a run.  
>>> 
>>>  - Paul
>>> 
>>> On Feb 22, 2016, at 8:22 PM, Curtis A. Meyer <cmeyer at cmu.edu> wrote:
>>> 
>>>> Hi Everyone,
>>>> 
>>>>   I am not sure if we have this capability yet, but as we move forward we are going to
>>>> want the REST files to contain the photon polarization. This is likely a function that
>>>> we have to call when we have decided what the correct photon is, but we should have
>>>> the hooks in place to do this on an event-by-event basis.
>>>> 
>>>> Curtis
>>>> ---------
>>>> Curtis A. Meyer			MCS Associate Dean for Faculty and Graduate Affairs
>>>> Wean:    (412) 268-2745	Professor of Physics
>>>> Doherty: (412) 268-3090	Carnegie Mellon University
>>>> Fax:         (412) 681-0648	Pittsburgh, PA 15213
>>>> curtis.meyer at cmu.edu	http://www.curtismeyer.com/
>>>> 
>>>> 
>>>> 
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>> 
> 
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