sPHENIX HCal discussion

[Edouard Kistenev <kistenev AT bnl.gov>]

Hi Dennis, for many years I tried to explain that so called polar coordinate are rather useless - waste of computer time. If you want something really new - why one of your students will not look into the design of the vector processors (chipsets)  customary used to manipulate images in computer games. Most likely the solutions people use are well documented.

As for the tilted HCal - you have no choice but to image calorimeter towers as 3-vectors pointing to centers of mass (gravity) which were all computed by Richie Ruggiero (sure he has tables) weighted by energy measured in a tower. This is an approximation. But every tower may and shell  be used as a jet seed. This jet will have its zero approximation vector (vector sum of all contributors). Use it to draw the line through the central two or more overlapping (radially) towers in Inner and Outer sections, decide on energy sharing along that axis and now build two or more representative “momenta” which can be used to localize shower CG’s in both section. Next comes global CG and leakage correction. This is just canvas of what can be done with calorimeter data viewed as point (local  СG) deposited energies in the need of a lot of manipulating and correcting. This is not exactly “clustering”, you will still need to find solution to enhance the quality of your image (field built of seeds) while conserving energy. 

Not a single operation in this whole analysis chain needs to know about  azymuthal and/or polar angles.

Edward

Sent from my iPhone

On Dec 10, 2019, at 4:35 PM, Perepelitsa, Dennis <dvp AT bnl.gov> wrote:

Dear HCal group,

I just wanted to bring to your attention that there has been an effort within the JS and Sims groups to implement a useful clustering algorithm for the I+OHCal.

Here is a pointer to today’s Sims meeting: https://indico.bnl.gov/event/5494/ 

One particular item which came up in the Sims meeting is whether the tilted nature of the calorimeter towers suggest that eta-phi may not be the best measure of 3-D topological connection. Perhaps you have some opinion on this.

Happy for any feedback,

Dennis

Dennis V. Perepelitsa
Assistant Professor, Physics Department
University of Colorado Boulder

On Dec 9, 2019, at 9:51 AM, Lajoie, John G [PHYSA] <lajoie AT iastate.edu> wrote:

Dear HCAL’ers:

 

It’s that time again – our next HCAL meeting will be tomorrow, Tuesday December 10^{tRuss h} at 11AM BNL time:

 

https://indico.bnl.gov/event/7183/

 

In addition to the usual reports on the sector assembly and tile testing, I have also added time for a discussion of the iHCAL cooling needs.  Russ has pointed out that we need to make a plan for any cooling testing we may want to do with the SS310 prototype so we can finalize the iHCAL design in the near future. 

 

Additional contributions are certainly welcome!

 

Regards,

John

 

John Lajoie

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu

 

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