[Solid_daq] Problem solved in Ye (Syracuse)'s LHCb TDR plot

[Xiaochao Zheng]

Hi Ye (Syracuse) et al.:

Reading LHCb TDR again I think I understand what's going on:

LHCb TDR can be found at
http://lhcb-calo.web.cern.ch/lhcb-calo/html/TDR/calo_tdr.pdf

The relevant figures are 3.3, 3.4, and 3.5.  In Fig.3.3, they showed the effect of the fluctuation in the energy deposit in the lead layer. It adds to the energy resolution of the ECal. For 2Xo, if I assume the first point is for 1 GeV electrons, it shows additional 4% fluctuation. Which for LHCb is okay but for us may be too large.

For Fig.3.5 which is what triggered the problem in our meeting: if you read the TDR carefully, this figure is to show the lead converter effect (with and without correction using preshower signal) to an ideal ECal, where the ideal ECal is with pre-defined resolution of 2.5%/sqrt(E). They added this ideal ECal behind the Preshower in the simulation and study how the performance change with and without prelead and preshower and their corrections. 

Hence, the 2.5%/sqrt(E) is NOT LHCb performance nor their designed specification. It's an artificial number input to the simulation.

To move forward, I suggest Ye look into:

1) scanning lead thickness from 0.5 to 2.0 X0, and study the resulting energy resolution; Paul is right that at an angle the actual lead thickness is larger than 2X0 for our setup right now and this will add additional fluctuation to the energy resolution.

2) when calculating energy resolution, consider correcting for the energy loss in the pre-lead using the preshower readout, as LHCb did in Fig.3.4

Xiaochao

----- Original Message -----
> From: "Xiaochao Zheng" <xiaochao at jlab.org>
> To: "solid ec" <solid_ec at jlab.org>, "Solid daq" <solid_daq at jlab.org>
> Sent: Wednesday, June 14, 2017 10:27:34 PM
> Subject: SoLID EC/DAQ meeting 9:30am Thursday 6/15/2017 CC F227

> Dear All:
> 
> We will have the EC meeting at 9:30am EST tomorrow, Thursday 6/15. The location
> at JLab is CC F227.
> 
> The call-in instruction is shown below. Meeting minutes can be found at:
> 
>  http://hallaweb.jlab.org/experiment/PVDIS/SoLID/EC/meetings/SoLID_EC_Weekly_minutes.html
> 
> If you have slides to present, please email them to everyone by replying to this
> email (or to me but only if there is a problem with the Reply-All) before the
> meeting.
> 
> Thanks,
> 
> Xiaochao
> 
> To join the Meeting:
> https://bluejeans.com/639268864/6242
> 
> To join via Browser:
> https://bluejeans.com/639268864/6242/browser
> 
> To join with Lync:
> https://bluejeans.com/639268864/6242/lync
> 
> To join via Cisco Jabber Video:
> https://bluejeans.com/639268864/6242/jabber
> 
> To join via Room System:
> Video Conferencing System: bjn.vc -or-199.48.152.152
> Meeting ID : 639268864
> Participant Passcode : 6242
> 
> To join via phone :
> 1)  Dial:
>	+1.408.740.7256
>	+1.888.240.2560
>	+1.408.317.9253
>	(see all numbers - http://bluejeans.com/numbers)
> 2)  Enter Conference ID : 639268864
> 3)  Enter Participant Passcode : 6242