sPHENIX EMCal discussion

[John Lajoie <lajoie AT iastate.edu>]

Hi John,

    Wow, thanks for the Herculean effort!

    Is there a plan to return to take the Al frame data as well as the HCAL cosmics in the future? ISU has some students we can send to FNAL to help out.

John

On 5/8/2018 6:10 AM, John Haggerty wrote:

Here is a summary of running after I sent around the email below. Again, thanks to Eric, Martin, Songkyo, and Debbie for making this possible.

- Eric and I had no problem getting the EMCAL onto the IHCAL

- The accelerator gods did not smile down on the plan to take data with the steel IHCAL and then swap it out for aluminum; there were vacuum problems in the MI Thursday going into Friday morning that made it so we couldn't start the steel data until Friday morning, and by then it was too late to get Todd's help rigging the calorimeters around.  After talking it over with John L., we decided we'd get data with the instrumented steel.

- I had some parasitic running with T992 on Friday which was useful to align the hodoscope with the beam.  The EMCAL and HCAL were decently close to where we wanted them, as far as I could see.  I collected quite a bit of 120 GeV p running for aficionados of high energy.

- Friday night, we removed as much material upstream as we could. Unfortunately, Lorenzo could not get everything out of the beam in the 1a area (there were detectors with short cables with their electronics not very well supported), so I had to live with it.  Lorenzo estimated that the central part of the beamline had maybe a quarter radiation length of material, but he wasn't sure how large the open aperture was before the beam hit support plates of indeterminate thickness.  Sigh.

- Forging ahead to strains of "You can't always get what you want," on Friday night and Saturday I did and energy scan, -4, -8, -12, -16, -20, -24, -28, -30.

- Reaching the highest energy possible in the low energy pion mode, I asked them to switch to pion mode and go to 40 GeV.  They worked on it for an our or two, and could not get that mode to work (we were getting about 600 events per spill, which I recorded, but it wasn't right, and I should have known that Saturday afternoon is not a good time to try something that hasn't been done in a while.

Anyway, we got what energy scan data we could which is described in the elog and the run index:

https://www.phenix.bnl.gov/WWW/sPHENIX/haggerty/t1044/2018b/index.php

On 5/2/18 11:01 PM, John Haggerty wrote:

As I mentioned in the HCAL meeting today, we think we have finished the EMCAL running we wanted on the 2c motion table, due to the efforts of Eric, Martin, Songkyo Lee, and Debbie Israel, so tomorrow, we plan to move the EMCAL and attach it to the steel version of the Inner HCAL.

The short summary of the data sets are:

dual channeling position (Fri Apr 27 19:06:25 2018)
  - energy scan 1883-1954
  - position scan 1957-2043
sphenix+5 (Sun Apr 29 10:02:25 2018)
  - energy scan 2045-2167
  - position scan 2168-2263
sphenix (Tue May 1 17:57:48 2018)
  - position scan 2280-2360
  - energy scan 2361-still running

During the day, we will be sharing time with T992.  I think they will be running 120 GeV protons, so we can just let it record data in 100k runs all day.  About 6pm, we'll go to an energy scan HCAL+EMCAL running. Looking at the 2017 data sets, it looks like 400k events at -4, -6, -8, -12, -16, -24, -28 would be the minimal data set we want.  We can take about 9k events/spill at energies where that is possible, so 400k is about an hour at the higher energies.  If we have more time, I would guess we would be best served getting higher statistics at -4 and -8, although there are logistical problems getting the Cerenkov pressures to where they need to be if we go high and then want to go low. Also, we did comparable positive running last year; if we want that again, we might want to reduce statistics to squeeze it in, but my recollection is that it wasn't particularly illuminating. I suggest we try to run for 12 hours up to Friday morning.

Friday morning, Todd said he could help me crane the aluminum HCAL, or HCAl, into place, we could do the 120 GeV thing during the day, and again at 6pm switch to a copy of the energy scan only but with aluminum in there.  I can finish that up Saturday before I leave on Sunday morning if all goes well.

Of course, plans can change due to various circumstances... but let us know here if that sounds reasonable; the die is cast to move the EMCAL early tomorrow, but we have until tomorrow night to settle on a run plan for the EMCAL+HCAL energy scan.

John Lajoie

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu