...

My question: can you let us know if you foresee that the above “highest harmonic” requirement would not be sufficient for your experiments?

EPIX Detector Integration Discussion (HR and M)

March 23, 2022 (cpo, lorenzo rota, phil hart, dan damiani, kaz nakahara, larry ruckman, mark McKelvey, matt weaver, jana thayer, valerio mariani)

• pedestal can change depending on configuration time
  • could have continuous pedestal calculation (dropped shots get strange when integrating over shots: could drop many shots to get a dark image)
• CDS: correlated double-sampling (removed baseline)
  • Phil asks: do we need to turn this off?
  • Lorenzo says noise will take a big hit if CDS disabled (maybe not a big issue at low-rate readout)
• Lorenzo isn't sure detector response is fast enough to reject MHz shots (10us OK, 1us tricky).  Harder to reject strong signal than weak signal.
  • different timing domains make it more difficult?
• Dionisio says this MHz response is a new requirement.  Should be discussed with Angelo.
• can the epix receive beam while it's being read out? ("gating")  answer: Maybe for epixHR (although Lorenzo/Dionisio will look to see if there is a sample-and-hold that may allow this), Yes for epixM (but need to investigate a bit more: could be issues)
  • fallback is to use "burst mode" to inhibit beam during readout (less efficient)
  • matt thinks that we'll have to inhibit the beam anyhow because response is different in different parts of the window
• maybe we send a RUN trigger at the beginning and a DAQ trigger at the end which has the "last shot" timestamp which gets attached to the image?
  • matt suggests setting acqWidth (currently 32 bits), and send down a DAQ trigger with the last-shot timestamp, and a RUN trigger with start-shot timestamp.
    • since acqWidth isn't precise Matt suggests dropping the beam to control the exposure (acqWidth clock will be tied to accelerator clock for UHR and beyond)
  • Dionisio says that dropped DAQ triggers could be problematic.  Matt's suggestion sounds better to him.
    • not a big deal to attach the second DAQ trigger timestamp to the image data
  • Lorenzo says that electronics settling time is 20-30us, so controlling the camera on timescales below that is problematic (related to Matt's comment about dropping the beam to be "conservative")
  • frame include both timestamps but the "real" one (from DAQ perspective) is the last-shot timestamp
  • want to start again as quickly as possible

easiest approach for camera, may make experiments more complicated (burst-mode, acqWidth precision):

• run the beam in burst-mode
• use acqWidth/RunTrigger/DaqTrigger (Phil worries about stability of acqwidth)

to do:

• need a future mtg with gabriel, georgi, kenney, angelo, aquila (use-case from georgi).  charge codes?
• Lorenzo/Dionisio think about "gating"