[Halld-cal] Preshower information in BCAL showers

[Curtis A. Meyer]

I also think that the addition of this quantity could be very useful.

Curtis
---------
Curtis A. Meyer			MCS Associate Dean for Faculty and Graduate Affairs
Wean:    (412) 268-2745	Professor of Physics
Doherty: (412) 268-3090	Carnegie Mellon University
Fax:         (412) 681-0648	Pittsburgh, PA 15213
curtis.meyer at cmu.edu	http://www.curtismeyer.com/



> On Aug 25, 2016, at 4:28 PM, Eugene Chudakov <gen at jlab.org> wrote:
> 
> The longitudinal separation of EM calorimeters helps considerably to
> identify e/pi. For this purpose a 10-cm thick LG preshower detector
> had been installed in Hall A in front of the LG calorimeters. It
> slightly compromised the overall energy resolution and made the
> detector calibration more tricky, but helped to gain a factor of ~5 in
> the pion rejection.
> 
> We should try this potential merit of the BCAL.  I think it is worth
> including the "preshower" signal for each BCAL cluster into the next
> data production. One would need a reasonably high statistics to verify
> the PID performance using the Dalitz electrons or the J/psi decays.
> 
> Eugene
> 
> On Thu, 25 Aug 2016, Lubomir Pentchev wrote:
> 
> Christina, thanks for your support. I like the idea to use it also for e/gamma separation. It can help to estimate our tracking efficiency, so far we have only a very rough idea what it is.
> 
> Lubomir
> 
> ----- Original Message -----
> From: "Christina Kourkoumeli" <hkourkou at phys.uoa.gr>
> To: halld-cal at jlab.org
> Sent: Thursday, August 25, 2016 2:50:17 PM
> Subject: Re: [Halld-cal] Preshower information in BCAL showers
> 
> Hi all, I second the voices expressed for the change. Both ATLAS and CMS us epreshowers and they are very helpful in e/pi separation and even in some cases of e/gamma separation when the track of the electron for some reason or other is not there. Cheers, Christine On 25/8/2016 9:23 μμ, Mark Macrae Dalton wrote:
> 
> 
> Hi all,
> 
> There is a proposal to alter the DBCALShower object to add an additional piece of information for each shower, this being the energy deposited in the first layer. The idea is to use this energy as “preshower" information to help with particle identification. The proponents desire to have this included in the next analysis launch which goes next week. No specific studies have yet been done to predict the effectiveness of this in our case, but in general it is a useful technique.
> 
> Implementing this would require a change to the REST data format to accommodate the new data member. This would essentially be a permanent change for reasons of backwards compatibility. These kinds of changes therefore require some amount of consensus. So, here is your opportunity to comment.
> 
> Best, Mark Macrae Dalton
> 
> 
> 
> 
> 
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