Minutes of ePIC ZDC meeting 17 Oct 2024
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Present: Yuji Goto, Gursimran Kainth, Alessio Ilari, Centro Kawade, Kyungseon JOO, Motoi Inaba,
 Po-Ju Lin, Sibata, Yongsun Kim. 
Chia-Yu Hsieh,  Michael Murray,   Ralf-Cristian Seidi, Yulia Furtetova Saehanseul Oh, Chia Ming Kuo


The meeting was focused on simulations and the question of whether we can reconstruct lambdas. The first two presentations were shown at the recent DNP meeting while the 4rd will be shown at the Korea Physical Society Meeting. 


Gursimran Kaith: DNP Talk
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Yulia asked that we use realistic MC which include lambda production. 
Ralf Christian Seidi said he was not sure that lambda are actually in simulations at the moment. 


Yulia: Can we identify lambda's that actually make it to the ZDC. 
Can we differentiate between a lambda and a neutron?
Perhaps the shower profile might be different 


Yuji mentioned that we hope to reconstruction lambda via photon daughter and total invariant mass. 

Yulia mentioned that it is important to try to get lambda's that don't decay. 


Saehanseul Oh: Asked about lambda=> pi0 plus 2 photons. These will only be 2 milli radians apart. 
We will need to use ECAL not just HCAL for photon reconstruction. 

He searches the ECal for 2 different peaks. Note that the neutron can of course shower early in ECAL or even in the EM section. When this happens it is harder to reconstruct the 2 photons. 


Allessi Ilari: DNP talk
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Looking at Pi0 and Lambda reconstruction. 
He has extracted the sampling fractions and energy resolutions for photons, pi_0 and neutrons. 

Photons lose most of their energy in the first 10 or so layers. 

>>> What clustering algorithm is used? Currently using DBScan  which makes no assumptions about the shapes of the showers. Allessi has tried to use the energy information to constrain the depth of the shower. 


Changhyun Oh: ZDC GEANT4 Simulation: Korea Physical Society 
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Looking at neutron resolution position resolution: It is better than Yellow Report requirement. Resolution is independent of theta. He can similar results when he adds in ECAL. 

For photons he is similarly better than YR requirement. 

In the future he will work on Ecal +Hcal photon energy/position resolution. 

Pi0 reconstruction  is next on his list since he would like to catch lambda in ZDC. This is similar to the work being done by the UConn group. 



>>> It would be good for both groups to connect with UC Riverside. Will need to be Asia morning, West Coast evening. 
Note Riverside has a very nice clustering algorithm. 

Next Meeting 31st October 9pm JST, 2pm CERN time. 

---------------------------- Submitted by Michael Murray ------------------------------------