The initial measurement plan for the ePixM5kHz detector can be seen below and is divided into two sets according to the available cameras (initially a non-back-thinned detector and later a back-thinned detector). The non-back-thinned detector will have roughly 500um of non-responsive Si in front of the active sensor area, so this device will not be suitable for beamline testing.
Prototype delivery schedule:
The current estimated delivery schedule for the ePixM5kHz prototypes asre stated in the table below.
Table 1. Prototype delivery schedule for the ePixM5kHz prototypes.
ePixM prototype version | delivery timeline | primary testing aim |
non-backthinned | July | Understand running modes; Initial evaluation of performance parameters; evaluate if detector response changes as we change the switching point; Try and identify a way to determine gains and pedestals for both high and low gain modes |
back-thinned | December | Full performance characterization; evaluation of detector timing; Linearity; switching behavior. Arrive at the calibration scheme. |
Measurement plans for the two prototypes:
Non-back-thinned testing:
Table 2. Initial measurement plan for the ePixM5kHz non-back-thinned prototype.
Measurement | Stimuli | measurement aim | comments |
Running modes | none | evaluate various readout schemes to see that they are running ok without dropped frames etc. when changing frame rates. | Assumes we have various potential run schemes, i.e. like run and daq trigger schemes for ePixHR. Require Dionisio or Lorenzo to know what running modes we have. |
Pedestals | none | Check pedestal values. Evaluate the common mode noise behavior for these detectors. | If we can verify that changing the switching point does not change the detector response, then obtain a low pedestal by changing the switching point. If not, we have to figure out how we can determine the low-gain pedestal. |
Temperature dependence of pedestals | none | Check how the magnitude of the pedestal shifts with the temperature | |
Temporal stability of pedestals | none | Evaluate the pedestal drifts, especially at turn-on. | To check stabilization periods before data collection can happen. |
Noise | none | Evaluate the noise level in both gains. | low gain evaluation assumes we can shift the switching point. |
Temperature dependence of noise | none | Evaluate the noise as a function of temperature to know the impact of cooling | |
Repeatable linearity behavior with varied switching point location | Charge injection | See if we can change the switching point and still have the same performance in linearity etc. | Needed in case we want to emulate Fixed gain mode operation; Will also show if we can determine the low gain and low pedestal by shifting the switching point. |
Single photon gain (high gain) | Ag flourescence, Marietta | First evaluation of the gain. | Evaluate the gains and check if the gain ratios between low and high stay the same across the detector (single gain evaluation for gain calibration if possible, otherwise, not). |
Single photon gain (low gain) | Ag flourescence, Marietta | First evaluation of the gain. | Assumes this can be evaluated by moving the switching point to always be in low. |
Temperature performance under vacuum conditions | none | evaluate the thermal response when the detector is operating under vacuum condition; evaluate outgassing levels for the camera. | Requires the new vacuum setup to be ready. Evaluating the outgassing level will be dependent on the vacuum level we can get in the setup. |
Back-thinned testing:
Table 3. Initial measurement plan for the ePixM5kHz back-thinned prototype.
Measurement | Stimuli | measurement aim | comments |
Repeat above measurements | Varied | ||
Timing behaviour | LCLS beam (XPP/MFX) | Evaluate the timing windows, evaluate the transfer function; get an estimate of the filter response time. | |
Linearity and switching behavior | LCLS beam (XPP/MFX) | Validating the linearity performance; evaluate the switching behavior; assessing the dynamic range; obtaining data for Gabriel's calibration functions if they work. | |
Pulsed X-ray single photon response | LCLS beam (XPP/MFX) | More accurate determination of the single photon gain. | |
Memory (ghosting) effects | LCLS beam (XPP/MFX) | To verify no ghosting effects are present and that we are fully resetting to baseline. |