[Halld-cal] Preshower information in BCAL showers

[Lubomir Pentchev]

Here's an example of how important this is for e/pi separation:

http://www.sciencedirect.com/science/article/pii/S0168900213004154

If don't have time to read the whole paper, look ant figs. 25 and 27. Practically, the inclusion of the preshower doubles the pion suppression factor. This is a well established and useful technique as Mark D. said. My estimation is that it will increase the number of identified J/Psi's by ~20%. To prove this however is technically very difficult, since you have to re-analyze all the runs from the evio files. 

Lubomir   

----- Original Message -----
From: "Matthew Shepherd" <mashephe at indiana.edu>
To: "Mark Macrae Dalton" <dalton at jlab.org>
Cc: "Hall-D Calorimetry" <halld-cal at jlab.org>, "Paul Mattione" <pmatt at jlab.org>
Sent: Thursday, August 25, 2016 2:29:16 PM
Subject: Re: [Halld-cal] Preshower information in BCAL showers

Modifications like this are good.

Likewise, I can think of quantities that may be useful for hadron/EM shower separation in the FCAL, so I expect similar additions down the road.  Without studying in detail though I'm not going to suggest any additions at present to the REST format FCAL shower.

Matt

> On Aug 25, 2016, at 2:23 PM, Mark Macrae Dalton <dalton at jlab.org> 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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