Sphenix-calibration-l mailing list

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

Hello Christof and Takao and the Calibration TF (cc the sphenix-calibration-l and also the members of the BUP Task Force),

Thank you for the email and input.    

It would be extremely helpful if you can put together a couple of slides in the next two hours and have a priority to participate in the meeting today.   Real decisions for this Beam Use Proposal at least (note the real run is still a few years off) need to be made shortly.

One item against pp running is that we need to know the detector works at full occupancy and then take some real AuAu data.    Switching to pp has a large cryo-week cost.   Even for just 2 weeks of pp, it costs 4.5 weeks.     Also, note that with only 2 weeks, it might be hard to have the pp triggers fully working for the first time.    I do not disagree with the argument that we may need pp for the energy scale and then one will need to combine Year-1,2.    Do you have some estimate of how much pp data in terms of photons or other observables would be needed for the "calibrations" and "quality assurance" you refer to for the different physics channels?     If you know how many of a particular channels (e.g. photons above pT > X GeV), we can estimate what may or may not be do-able.

It may well be that the first year is essentially mostly commissioning and that the big physics output will be from the combined Year-1,2.     I am not sure that is a bad thing, noting that I would expect for many observables it will take more than a year of analysis to have physics quality results -- it is a completely new collider detector.   That is not the same as saying there would be no physics from Year-1 at all, but maybe observables that are less sensitive to the full calibration.

Sincerely,

Jamie

||------------------------------------------------------------------------------------------
|| 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 
||------------------------------------------------------------------------------------------

On Fri, Aug 14, 2020 at 7:55 AM Takao Sakaguchi <takao AT bnl.gov> wrote:

Dear Jamie

  We, calibration TF, appreciate that the BUR TF are working hard
for finalizing a beam use proposal for the PAC meeting in Sep.
Here we would like to provide you with our view on the run plan.

  From the calibration point of view, it is essential to have decent
p+p dataset prior to performing precision physics in A+A collisions
which we are aiming for in sPHENIX. The p+p dataset provides
handles on energy scale and resolution of calorimeters that are
essential for jet-photon correlation measurement, tracking resolution
and TPC distortion correction for Upsilon spectroscopy, and etc.

  Accordingly, we think we won't be able to publish results from the
A+A data taken before the high statistics p+p data are obtained.
We note that the quality assurance of the A+A data may not be
performed well enough either. The peripheral A+A collisions may be
useful, but the statistics will be too low to perform good enough
calibration for rare probes such as jet-photon correlation.

  We appreciate that you take this view into account on finalizing
the run plan. The calibration TF members have been encouraged
to join the BUR discussion today if they can make.

Best,
Christof and Takao for the calibration TF