sPHENIX is a new detector at RHIC.

[Jamie Nagle <jamie.nagle AT colorado.edu>]

Hello sPHENIXers,

Thanks for the very positive attendance and useful discussion at the sPHENIX Beam Use Proposal open meeting today:

https://indico.bnl.gov/event/9139/

Here are some minutes and action items.   Please feel free to add items I missed or items from post-meeting discussions.

Sincerely,

Jamie, for the sPHENIX BUP Task Force

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* slides from  Calibration Task Force (https://indico.bnl.gov/event/9139/contributions/40526/attachments/29955/46739/BUR_input_Aug14_2020.pdf)

  Note that there is also a discussion thread on this topic on sphenix-calibration-l if you are not subscribed.

* concerns about whether we can produce physics from Year-1 without pp running

* separate issues of jet (in particular Jet Energy Scale / Resolution (JES/JER) and for tracking

  -- likely that peripheral AuAu not sufficient for JES/JER in particular via photon-jet channel (Action item was for Dennis to check rates for 60-90% as example - already sent around 5 pb^-1 is actually not negligible though small)

  -- unclear whether tracking could be checked in peripheral...   Also, the issue of high IBF / fluctuations thereof could be solved by some low luminosity runs?   Needs follow up

* some different views on whether Year-1 is mostly commissioning or is really a physics run (general agreement we do not want to rush "wrong" results)

* some observables are less sensitive to the JES, e.g. dijet asymmetry A_J, as opposed to steeply falling inclusive spectra

* lots of good discussion on different methods for JES/JER; it would be good in the coming months to really step through different methods for RHIC and see what the best paths are

  -- Yen-Jie mentioned in CMS using single isolated hadrons, dijet, photon/Z-jet;  Aaron mentioned multijet;  Particle flow matching might be important at lower pT

* useful figure of statistical limits from photon-jet for JES:   https://indico.bnl.gov/event/9139/contributions/40526/attachments/29955/46741/image001.jpg

  -- Action item was for Aaron to update this figure with luminosity projections from the nominal plan, also with input for potential Year-1 pp (what does 15, 30, 60 pb^1 look like as examples)

  -- Aaron generated the photon-jet JES plot for different potential pp luminosities - excellent!  -- linked here https://indico.bnl.gov/event/9139/contributions/40367/attachments/29963/46757/CompareSqrtsBUR.pdf

* general agreement - we should have a paragraph in the sPHENIX BUP Executive Summary with some words to the effect that "if the AuAu running and detector commissioning and quick analysis feedback go exceptionally well, in the 28 week or more scenario we foresee the possibility to request N cryo-weeks for pp running for commissioning that system and potentially providing key input for JES/JER and more....".    The $N$ needs to be determined -- see below.

* there was discussion about how much more than the paragraph to include.    Some thought a section with some details would be useful.

-- Action item - John Haggerty and Jamie will email C-AD (Wolfram et al.) to ask if the switching time might be shorter for pp if there was no polarization requirement and perhaps lower luminosity (email sent!)

-- Action item - by Tuesday next week John and Jamie will develop a draft commissioning plan for pp in terms of number of weeks that ensure safe operation, beam stability checking, and then projected luminosity for a short run.

* general agreement - strong emphasis needs to be made in the Executive Summary that this Year-1 run needs to be under sPHENIX control - do what is best for timely commissioning and shake out of new collider detector

* slides from Jet Group (Dennis) - (https://indico.bnl.gov/event/9139/contributions/40508/attachments/29947/46729/dvp-sPHENIX-BUR-8-14-20.pdf)

* Projections for inclusive jets/photons/hadrons with statistical uncertainties from Year-1,2,3 combination and with additional Year-4,5

  -- agreement that inclusive jets are not the argument on the figure for x2-3 statistics, but we all know that a factor of 2-3 is a lot

* Figure of photon-jet x_J matching JEWEL, very nice.    Action item - Dennis to calculate statistical uncertainty from fake/uncorrelated jets in AuAu case (more realistic)

* Useful comments on systematic uncertainties, though unlikely to get that all the way through on this BUP timescale

* Comment to make fonts/layout/labels uniform between plots in BUP -- Action item for Jin, Dennis, Sasha B to coordinate (in the works)

* Action item - working to get Upsilon updated projections, Tony, Marzia, Sasha L are working on that (wind storm in Iowa interfering!).

Again, the goal is to have a nearly full draft of BUP by next Friday, August 21 for Collaboration distribution (note that this leaves a short comment period -- plan to read it over the weekend afterwards!).

Lastly -- general observations -- the BUP exercise is bringing up a number of issues that will take more than 1-2 weeks to resolve and highlights that we should make sure to stay on top of these issues in the next months.

There will definitely be an updated BUP next year and iterations from what we present now (also based on feedback from the PAC).

Other missing items?   Feel free to add.

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|| James L. Nagle   
|| Professor of Physics, University of Colorado Boulder

|| EMAIL:   jamie.nagle AT colorado.edu
|| SKYPE:  jamie-nagle        
|| WEB:      http://spot.colorado.edu/~naglej 
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