Page History

...

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

Second Meeting

April 13, 2022.  Main goal: to connect hutch scientists with detector builders to determine what can reasonably be achieved with the existing hardware.

Georgi requests:

Need I0 normalization.  Ideally 1MHz continuous beam with slower epixM (5kHz).

Andy requests:

TXI Need I0 normalization.  Burst mode is OK.  SPI with 10kHz beam but 5kHz imaging (most are blank).  How long does it take the detector to clear if another signal come in?  Same question as beam coming in while detector is reading out.

daq deadtime is an issue (can lose data from other detectors that contribute to image)

epixHR: 3 parts: presampling, reset front end (24us), integrate (minimum 24us?) then readout (sum of all these is 200us → 5kHz).  can't have any pulse come during reset because of the CDS (correlated double-sampling).  can reduce the R0 time (reset time) but can't be zero.  increasing the integration time, but adds to the total time (reducing rate).

dionisio/lorenzo say there is a sample/hold that can take a snapshot of the charge after integration.  Angelo says need to be tested if there are effects from outside the integration window (should not be a problem)

Can reduce the frame rate of the camera by increasing integration time (lowering frame rate) but leakage rate starts to matter which is more noise.  Can lower temp from +10 to -30 to reduce leakage current.

Angelo says 100us should be fine for epixHR.  epixM is more sensitive.  need to see how big the integration time can be for epixM.

Chris K. says that have to run beam at about <50kHz to avoid hitting the integration window.

Angelo says burst mode is key.

Andy says spectroscopy can really use the higher rate pulses.

Executive summary:

• need burst mode (no beam outside integration window)
• daq needs to think about timestamping requirements in burst mode
• longer integration requires better cooling (Chris K. suggests limit of 400us integration? maybe 800us? Angelo thinks above >100us for epixM could be problematic, but needs testing)
• different running modes require different calibrations (pedestals, gains, offsets)
  • need to have set of standardized conditions to choose from (requires psana support)
• Action item: test longer integration times for epixHR and epixM (400us or 800us). (2 weeks?)
• Action item: Andy/Georgi provide a few use-cases
• Action item: Detector group produces a list of examples that "make sense" e.g. frame rate vs. deadtime and noise issues
• Needed May 2023
• Need to know if epixM needs better cooling (there are limits to what can be done)