Studies towards understanding how operations of our specific TPC's gating grid affect/determine ion back flow ("IBF", a form of space charge) into the TPC.

Goals:

• Verification of our choice of standard operations
• Possible alternative modes of operation
  1. Semi-streaming mode
     • Tonko's idea of 1 triggered event, followed by an extended open duration to accept additional minbias events at minimal excess TPC data
     • Possible for high luminosity conditions, e.g. 2022+
  2. Streaming in a fill-and-flush mode
     • Under low luminosity conditions, such as BES 2019-2012
• Publication

2015 study (data taken on June 16, 2015) was succesful at demonstrating some limited understanding, but revealed it was a bit more complicated than we thought. Since then, we've done simulations to better explain the observed results. Now, we would like to take more data to confirm our understanding by exploring more of the phase space of operations.

The following graphic shows our current understanding along with the 2015 results:

 


Proposed test:

• Probe more data points on this phase space
• Requirements:
  • Minimum bias trigger
  • Full luminosity (want to trigger as soon as possible after intended TPC dead [gating grid closed] time ends)
  • Jeff L.'s time distribution between TPC triggers
  • Up to 3 hours of beam time
    • 2015 study was completed in under 1.5 hours, but we would like to explore more of the phase space this time
• Data will be for this study only, and unusable for physics
• Preference to do it during 62 GeV dAu, when there are not as many physics priorities
  • Perhaps second half of week to make sure we're ready, and everything else is stable

-Gene