[G12] energy corrections, I'm confused

[Lei Guo]

I'm equally confused by the tagger-id dependent corrections. I thought  
the run-dependent correction is only supposed to correct the overall  
electron beam energy. Did I miss something?

Lei
On Feb 16, 2012, at 1:50 PM, Saini, Mukesh wrote:

> Thing that is throwing me off here is that the numbers differ in the  
> 4th and 5th decimal places too. and also it seems for the same  
> tagger-id they are rounded off to different numbers. I would expect  
> the rounding error to be on the 6th digit of 1.
>
> Anyways, If a1c accounted for the changing electron beam energy  
> during our cooking pass for different runs ( Let's say electron  
> energy between 5.710 - 5.720 ),
> then is the single tagger-id to photon-energy conversion posted  
> still valid?
>
> If yes, then how did the a1c account for the shift in electron  
> energies?
> If the tagger paddle gives me the same energy back for an incoming  
> electron of 5.71 GeV as well as 5.72 GeV then I have a lack of  
> understanding of this process and the way a1c accounted for the  
> incoming electron energy-change during our cooking pass.
>
> I am trying to code this in my ntuple-maker and this is throwing me  
> off. We should explain this in a small section/note on the wiki.  
> Also please reply with your insights.
>
> Thanks,
> Mukesh.
>
>
>
>
>
>
>
>
> ________________________________
> From: g12-bounces at jlab.org [g12-bounces at jlab.org] on behalf of Paul  
> Eugenio [eugenio at fsu.edu]
> Sent: Thursday, February 16, 2012 10:36 AM
> To: g12
> Subject: Re: [G12] energy corrections
>
>
> Yes, this makes sense.  Floats have precision of 6 decimals whereas  
> doubles have 15 decimal precisions.  While we are performing our  
> calculations as double precisions, we are saving them to disk as  
> floats.
>
>
> --
> Prof. Paul Eugenio
> Florida State University
> Department of Physics
> Tallahassee, Florida,  USA 32306
>
> (850) 325-0314
> eugenio at fsu.edu<mailto:eugenio at fsu.edu>
>
>
>
>
> On Feb 16, 2012, at 8:47 AM, Johann Goetz wrote:
>
> Actually those differences you see are because the 32bit floating  
> point numbers in the BOS files are only good to 5 digits at best,  
> and the paddles' widths are about 5 MeV anyways.
>
> On Wed, Feb 15, 2012 at 3:03 PM, Mukesh Saini <msaini at admin.fsu.edu<mailto:msaini at admin.fsu.edu 
> >> wrote:
> Hello,
>
> I checked a few runs in my data and compared the photon energies in my
> data-ntuples against  the energies provided in the file:
>
> /group/clas/parms/pcor/g12/tagger_energies_reported_by_tagr_bank.txt
>
> Some of the photon energies in my data-ntuples are off by fractions of
> MeV (at most 0.5 MeV) from those in the file. I am guessing that is  
> due
> to some tage correction function applied in CLASEvent. I couldn't find
> one during the first lookup of the code I did and I will look into  
> this
> further.
>
> In case, anyone is aware where this further correction gets applied,  
> and
> if its necessary, We might have to add this correction in
> post-processing Beam Energy Corrections also. To reverse lookup and
> correct the tage paddle seems cumbersome if the photon-energies in the
> data-ntuple's don't match the ones in the table provided. I think I  
> will
> just reskim my data to include the tage paddle number, if that is  
> the case.
>
> Mukesh.
>
> On 02/15/2012 01:32 PM, Johann Goetz wrote:
>>
>> It describes the files and how to interpret them. Currently I only  
>> had
>> enough statistics to do 481 of the runs. I'm working on getting the
>> rest right now. Tomorrow, I intend to address momentum corrections  
>> and
>> I should have most of the
>
>
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> --
> Johann T. Goetz, PhD.<http://sites.google.com/site/theodoregoetz/>
> jgoetz at ucla.edu<mailto:jgoetz at ucla.edu>
> Nefkens Group, UCLA Dept. of Physics & Astronomy
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