Investigation of Detector Behavior At High Count Rates for the Purple Crow LidarCreate workshop

Investigation of Detector Behavior At High Count Rates for the Purple Crow Lidar

Investigation of Detector Behavior At High Count Rates for the Purple Crow Lidar

G. Farhani, R. J. Sica, P.S Argall

Contents Photomultiplier tubes (PMTs)Analog and Digital detectionMerging profiles Making synthetic dataFinal results

Photomultiplier Tubes

Analog Mode and Digital Mode

Photon counting and dead-time correction

Figure: Licel Photomultiplier ModuleR7400 hand book

Merging the Photon Counts (PC) and Analog Detection (AD) profiles

Convert AD to virtual count rate units:

PC = a* AD +b

Errors contributed to the merging process?

Figure: The PC (black) and converted AD (red) profiles. Petty & Turner paper (2009).

Synthetic PC profile from Lidar equationKnowing Lidar equation:

N: number of returned detected photons A/4Z2 : the effective area of telescopet: the integration time z: the bin size: system-specific receiver efficiency B: the background count rate-emitted: transmittance of the photons -return: return transmittance of the photonsO(z): the overlap function of the receiver field of view

: the laser power

: the scattering cross section of the target n(z): the number density of scatterers

Merging the synthetic data and error contributed to it.The merging regions: when both profiles have linear behavior: We use Pearson momentum correlation test 10 to 20 MHz and 0.5 to 5 MHz

Monte Carlo results: Error from merging process is almost zero.( The order of 10E-12)

.

The effect of dead-time correction

Figure1: for the count profiles there is a small difference between two profiles (the one that has dead-time correction and the one that has not)Figure2: Two regression of AD-PC are shown, with or with out dead-time correction

Temperature profileThe effect of dead-time correction on temperature profiles can be to 8 K. (1.4 % Percentage difference)(Different merging regions might lead to bigger or smaller difference)

Results and feature worksThe use of AD-PC combination extends the dynamic range of detection, meanwhile it does not introduce any effective error.A distinct error to the temperature profile can be seen if the dead-time correction is not applied. The difference between the temperature profiles considering the effect of dead-time correction can be up to 1.5 %Choosing the threshold for merging region can effect the dead-time correction error, but it does not effect the merging process error. The dead-time correction uncertainty and its contribution in final temperature profile

Thanks to: