[Frost] helicity info in g9b data

[Franz Klein]

Eugene and Mike,
unfortunately there are ~120 cooked files in these ranges where the 
helicity information is screwed up. For extracting T it does not matter - 
and if you use a condition like

  int cntrlmask = 0x40000000;    // bit30 flag for corrected helicity
   int helmask   = 0x20000000;    // bit29 corrected helicity bit
   int helicity = (HEAD[0].TRIGBITS & helmask)? 1 : -1;
   if( !(HEAD[0].TRIGBITS & cntrlmask) ) helicity=0;

you can use all events for observables not depending on beam helicity and 
fill helicity dependent histograms only if helicity!=0

Sorry,
Franz


On Thu, 19 Jan 2012, Eugene Pasyuk wrote:

> As we discussed at today's meeting I'll prepare detailed summary table
> of run conditions.
> Meanwhile, to Mike's question about runs with circularly polarized beam.
> The first group is runs 62321-62704 @E_e=3081.73 MeV (3 pass)
> The second group is runs 63508-63599 @E_e=2265.99 MeV (2 pass) after
> target incident. Target polarization is lower.
>
> -Eugene
>
> On 1/19/12 16:44 , Michael Dugger wrote:
>> Franz,
>>
>> Thanks for the info.
>>
>> If you know of a few runs that you are certain had circular polarization,
>> that would be great. We are not interested in the actual helicity state of
>> any event, instead we would like to try and see the azimuthal offset angle
>> of the transverse magnetic field by looking at pion T asymmetry.
>>
>> If you don't know of, or remember, which runs definitely had circular
>> beam, we will just wait for you to finish investigating the situation.
>>
>> Take care,
>> Michael
>>
>> On Thu, 19 Jan 2012, Franz Klein wrote:
>>
>>> Hi,
>>> this morning I claimed that the helicity information was correctly
>>> extracted for most of the runs ... but that was not correct: by chance I
>>> looked into cooked files where it worked!
>>> Since we had delayed reporting, in part by 8 helicity intervals, in part
>>> by 16 intervals, I have to get the correct sequence of helicity scaler
>>> events (or cannot resolve the helicity info for a given helicity
>>> interval). However, often the helicity info in the gated and ungated
>>> scaler banks did not match during g9b, so I have to figure out how to
>>> solve that over the next days ...
>>> This concerns ~60% of the cooked files (as you see by chance I didn't
>>> look into bad files ...)
>>>
>>> When I am done with that, I will write a wiki page about helicity info,
>>> etc. (similar to
>>> http://clasweb.jlab.org/rungroups/g14/wiki/index.php/Beam_Polarization_%28Circ.%29
>>>
>>> Greetings
>>> Franz
>>>
>>> ===============================================================
>>>                    Franz J. Klein, Associate Professor
>>>                    CUA, Department of Physics
>>>                    Washington, DC 20064
>>>    office: Hannan Hall 206          phone: 202-319-6190
>>>    or: Jefferson Lab,CC F-243       phone: 757-269-6672
>>> ---------------------------------------------------------------
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===============================================================
                   Franz J. Klein, Associate Professor
                   CUA, Department of Physics
                   Washington, DC 20064
   office: Hannan Hall 206          phone: 202-319-6190
   or: Jefferson Lab,CC F-243       phone: 757-269-6672
---------------------------------------------------------------