[Olympus] Tracking Update

[Axel Schmidt]

Hi Norik,

On Jul 28, 2014, at 9:11 , Norair Akopov wrote:

> 
> Dear Axel,
> 
> Thanks for sending your sildes.
> Because of I'm not sure to be able to connect today via EVO from Yerevan
> I have a question:
> 
> What means "No Smearing" on page 24?

"No smearing" means that the digitization does not include any smearing of the timing signals of the drift chambers. In the final version of the digitization, we will include some artificial smearing of the timing signals in a way that matches the random processes that distort the timing signals in real data. However, for this study, we chose to include no time smearing. That way, the time-to-distance function used by the tracker was the perfect inverse of the distance-to-time function in the digitization. This removes any effect that an imperfect time-to-distance function would have. We were interested in studying the tracking algorithm, and not yet worrying about improving the time-to-distance function.

> As to the meaning of resolution defined as X_recon - X_gen I suppose you 
> are showing MC data?

Yes, this is MC data. I have updated my slides to say "Fit" and "Sim." to avoid confusion that real data is being shown.

> If not (because you have just "Data" marked box on 
> all panels), then again what means "No Smearing" because in data all is 
> naturally smeared..

I agree.

> Also do you have any estimation on expected resolution with smearing?

No, not yet. We still need to study this.

> I mean your expected resolution W/O smearing is changed (page 27) from ~36 
> MeV (EAA) to ~27 MeV (new reco algorithm), does it mean we should expect 
> for real data similar change i.e. from ~300 MeV to ~220 MeV?

I wanted to show that the resolution we expect (from the intrinsic resolution of the drift chambers) produces the momentum resolution of the EAA tracker. I asked myself: "If I know that the position resolution is 0.27 mm, what kind of momentum resolution should I expect." Doing a naive, back-of-the-envelope calculation I find:

We should expect a resolution of ≈ 54 MeV
Compared to an EAA tracker resolution of 36 MeV

Naturally, these numbers will increase substantially if we introduce smearing in the digitization. However we have already made some substantial improvements (notably in the magnetic field) which will improve the resolution for the next iteration of tracked files. 

Cheers,
Axel

> 
> Thanks in advance.
> 
> Best regards,
> Norik
> 
>  On Mon, 28 Jul 2014, Axel Schmidt 
> wrote:
> 
>> Dear colleagues,
>> 	I apologize for the delay: I've just posted my slides for today's tracking update. They are available from the wiki:
>> 
>> https://olympus-docu.hiskp.uni-bonn.de/dokuwiki/doku.php?id=meeting_20140728
>> 
>> Best regards,
>> Axel
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