[Halld-physics] Polarization values

[Michael Dugger]

Richard,

I will make the change and send out the new code.

Take care,
Michael

On Tue, 19 Sep 2017, Richard Jones wrote:

> Hello Mike,
>
> It might be better to plot the same quantity on the x axis across the
> entire plot, even if the statistical errors turn out to be somewhat larger.
> Whatever the acceptance of the TAGH might be, it IS what defines the tagged
> beam at energies above the TAGM. Unless someone has a physics channel for
> which they do not need to know the energy of the beam photon, it is only
> the tagged flux that is of any interest to GlueX analyses.
>
> in response to Sascha,
>
> The PS energy contains a polarization bias. If one is in a flat part of the
> spectrum then this will average out, as you say. But if you are sitting in
> a steep location, say just above the coherent edge then the PS has a
> different energy resolution depending on the polarization of the photon. If
> the pair comes out in the horizontal plane then it has an energy spread on
> the order of 100 MeV, as Mike showed. The resolution for vertical-plane
> pairs is much better. This would be expected to produce a different
> steepness of the coherent edge in PARA and PERP runs. This is what I mean
> by artifacts. But Mike is using the TAGM energy in the region of the
> coherent edge, so that is good.
>
> -Richard Jones
>
>
> On Tue, Sep 19, 2017 at 12:04 PM, Michael Dugger <dugger at jlab.org> wrote:
>
>>
>> Richard,
>>
>> In the coherent peak I use the tagger energy. For energies outside the
>> coherent peak, I use the PS. I use the PS outside the coherent peak because
>> of statistics.
>>
>> For the Spring 16 priority set, I use the tagger energy for energies
>> bewteen 8.4 and 9.4.
>>
>> For the Spring 17 runs, I use the tagger energy for energies between 8.2
>> and 9.3.
>>
>> As long as people are within the energy ranges given above, the tagger
>> energy is being used to bin the data.
>>
>> If you don't like the mixing of PS and tagger for the energy binning, I
>> can easily modify the code so that only tagger information is used. For the
>> most part, it will just pump up the error bars for the energy regions
>> outside the coherent peak.
>>
>> Take care,
>> Michael
>>
>>
>> On Tue, 19 Sep 2017, Richard Jones wrote:
>>
>> Mike,
>>>
>>> These are very nice results, good to see that the spread between the
>>> different polarization orientations is now much less than we were seeing
>>> before, esp. 2017.
>>>
>>> One question about the energy scale. Are you using the tagger energy to
>>> decide which bin each event should go into? Now that we know the PS energy
>>> is entangled with the polarization, to produce a spectrum free of
>>> artifacts
>>> we should only be using the tagger energy to make this spectrum.
>>>
>>> -Richard
>>>
>>> On Tue, Sep 19, 2017 at 10:08 AM, Michael Dugger <dugger at jlab.org> wrote:
>>>
>>>
>>>> Hi,
>>>>
>>>> I have code that creates the polarizations for
>>>> Spring 16 (priority set 1) and Spring 17 data
>>>> at
>>>>
>>>> https://userweb.jlab.org/~dugger/triPol/makePolValsV2.tar
>>>>
>>>> Once you have un-tarred the file, go through the steps in
>>>> the README file to generate the polarizations.
>>>>
>>>> Take care,
>>>> Michael
>>>>
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>>>>
>>>>
>>>
>