[Clas12_verystrange] just some numbers to throw at ya

Fri Jun 15 07:10:45 EDT 2012

Folks, we should not go this avenue and say negative things about 
linearly polarized photons in Hall-D. GLUEX is planning to do to a 
couple of things take care of the issues with photon polarization. 
Firstly, they are going to implement actual polarimetry in addition to 
just analytical calculation. Secondly, they will have better monitoring 
of transmission and spectrum shape after collimation using pair 
spectrometer.

-Eugene

Derek Glazier wrote, On 06/15/12 06:55:
> I think the point is the systematic uncertainty will certainly be
> smaller. As you know with the coherent bremsstrahlung technique there
> are (at least) two significant systematic uncertainties, the first is
> the reliability of the polarisation calculation from the spectral shape
> of the energy distribution, the second is that in reality the coherent
> peak (and thus polarisation) moves with time and so there may be some
> mismatch of calibrated to actual polarisation for a particular event.
> The magnitude of these uncertainties is hard to predict for GLUEX. The
> linear polarisation from quasi-free photoproduction is certainly more
> reliable from this point of view. However, I think we have to be careful
> not to make too much of a point here as it would require some negative
> statement on coherent bremsstrahlung and we are not sure how much of an
> advantage it really provides.
> Cheers
> Derek
>
> On 06/14/12 22:02, Michael Dugger wrote:
>> Perhaps I am thinking about this all wrong, but I don't see how we gain
>> much -if anything- by measuring the polarization on an event basis.
>>
>> -Michael
>>
>> On Thu, 14 Jun 2012, Lei Guo wrote:
>>
>>> We expected this question, and it was discussed at our weekly meeting.
>>> Basically, if it comes up, we should stress that it IS normal that
>>> different experiments will do similar yet complimentary measurements,
>>> such as STAR and PHENIX, and CLAS12 and GLUEX (Meson spectroscopy,
>>> e.g.). Gluex obviously has the advantage of acceptance, but CLAS12 has
>>> the advantage of resolution and PID. We also have the advantage of
>>> measuring the beam polarization on an event basis, while GLUEX beam
>>> polarization is obtained from calculation.
>>>
>>> In any case, our physics goals are similar, and it should be desirable
>>> that two experiment can cross check each other.
>>>
>>> Lei
>>> On Jun 14, 2012, at 3:50 PM, Carlos Salgado wrote:
>>>
>>>> Igor
>>>>
>>>> Yes, of course the question should go both ways.... just interested
>>>> in how we can answer it.
>>>> (It seems that Gluex is not proposing a measure of omega?)
>>>> -Carlos
>>>>
>>>>
>>>> On Jun 14, 2012, at 9:54 AM, Igor Strakovsky wrote:
>>>>
>>>>> Carlos,
>>>>>
>>>>> How is about alternative question addressed to GluEx?
>>>>>
>>>>> Igor
>>>>>
>>>>> On Thu, 14 Jun 2012 09:10:52 -0400 (EDT), Carlos Salgado<salgado at jlab.org
>>>>> wrote:
>>>>>
>>>>>> Lei
>>>>>>
>>>>>> As you will know well (being a GluEx member), GluEx is sending a
>>>>>> Cascade/Strange-hybrid proposal to PAC39.
>>>>>> How is the CLAS12/FWT compare with them? What can we do better?
>>>>>> Perhaps PAC will be interested to know.
>>>>>> -Carlos
>>>>>>
>>>>>> ----- Original Message -----
>>>>>> From: "Lei Guo"<lguo at jlab.org>
>>>>>> To: "Johann Goetz"<jgoetz at ucla.edu>
>>>>>> Cc: "clas12 verystrange"<clas12_verystrange at jlab.org>
>>>>>> Sent: Monday, June 11, 2012 6:05:47 PM
>>>>>> Subject: Re: [Clas12_verystrange] just some numbers to throw at ya
>>>>>>
>>>>>>
>>>>>> What about the moments for the accepted events?
>>>>>>
>>>>>>
>>>>>> On Jun 11, 2012, at 5:05 PM, Johann Goetz wrote:
>>>>>>
>>>>>>
>>>>>> distributions were certainly isotropic in the CM frame of the parent
>>>>>> particles.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Do you mean the helicity frame of the Xi(1820) and Lambda? I'm
>>>>>> supposed to
>>>>>> still go to the w&m workshop. But I will meet you first in the
>>>>>> morning.
>>>>>> Tomorrow we will try to weight the generated events with the help
>>>>>> of Dennis,
>>>>>> I guess?
>>>>>>
>>>>>>
>>>>>> Lei
>>>>>>
>>>>>>
>>>>>>
>>>>>> ***These are for generated events***
>>>>>> I need to send these events through the fastmc to get the acceptance
>>>>>> equivalent.
>>>>>>
>>>>>> H (1, 0, 1, 1) = 2.593e-04 + i 2.961e-04
>>>>>> H (1, 0, 3, 1) = 5.957e-04 + i 7.105e-04
>>>>>> H (1, 0, 3, 2) = -5.373e-05 + i 2.210e-05
>>>>>> H (1, 0, 3, 3) = 2.824e-06 + i -6.330e-07
>>>>>> H (1, 0, 5, 1) = 8.350e-04 + i 1.082e-03
>>>>>> H (1, 0, 5, 2) = -1.408e-04 + i 5.941e-05
>>>>>> H (1, 0, 5, 3) = 1.204e-05 + i -5.116e-06
>>>>>> H (1, 0, 5, 4) = 2.517e-06 + i 1.138e-05
>>>>>> H (1, 0, 5, 5) = 6.033e-07 + i -6.525e-07
>>>>>> H (1, 1, 1, 1) = -1.067e-05 + i 7.996e-06
>>>>>> H (1, 1, 3, 1) = -8.773e-06 + i 1.105e-05
>>>>>> H (1, 1, 3, 2) = -5.633e-06 + i -4.329e-06
>>>>>> H (1, 1, 3, 3) = -1.048e-07 + i 3.548e-06
>>>>>> H (1, 1, 5, 1) = -6.181e-06 + i 1.555e-05
>>>>>> H (1, 1, 5, 2) = -9.076e-06 + i -3.540e-06
>>>>>> H (1, 1, 5, 3) = 2.206e-07 + i 9.737e-06
>>>>>> H (1, 1, 5, 4) = -2.169e-06 + i -1.148e-07
>>>>>> H (1, 1, 5, 5) = -2.438e-07 + i -2.848e-07
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Johann T. Goetz, PhD.
>>>>>> jgoetz at ucla.edu
>>>>>> Nefkens Group, UCLA Dept. of Physics&   Astronomy
>>>>>> Hall-B, Jefferson Lab, Newport News, VA
>>>>>> Office: 757-269-5465 (CEBAF Center F-335)
>>>>>> Mobile: 757-768-9999
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