Silicon PIN photodiode applied to acquire high-frequency sampling XAFS spectra

Experimental techniques based on SR facilities have emerged with the development of synchrotron radiation(SR)sources.Accordingly,detector miniaturization has become significant for the development of SR experimental techniques.In this study,the miniaturization of a detector was achieved by coupling a commercial silicon PIN photodiode(SPPD)into a beamstop,aiming for it not only to acquire X-ray absorption fine structure(XAFS)spectra,but also to protect the subsequent two-dimensional detector from high-brilliance X-ray radiation damage in certain combination techniques.This mini SPPD detector coupled to a beamstop was used as the rear detector in both the conventional sampling scheme and novel high-frequency(HF)sampling scheme to collect the transmission XAFS spectra.Traditional ion chambers were also used to collect the transmission XAFS spectra,which were used as the reference.These XAFS spectra were quantitatively analyzed and compared;the results demonstrated that the XAFS spectra collected by this SPPD in both the conventional sampling scheme and HF sampling scheme are feasible.This study provides a new detector-selection scheme for the acquisition of the quick-scanning XAFS(QXAFS)and HF sampling XAFS spectra.The SPPD detector presented in this study can partially meet the requirements of detector miniaturization.

The development and application of the test system for the silicon pixel modules in HEPS-BPIX

Background HEPS-BPIX is a prototype of photon counting pixel detector developed for the High Energy Photon Source.It consists of 16 silicon pixel modules which should be tested individually to ensure the function and performance.Purpose Due to various factors such as the non-uniformity of the processes and voltage drop,the response of each pixel in the silicon pixel module is not identical completely.The response difference of pixels can be minimized by the threshold calibration.This system is developed for the quality test and calibration of the silicon pixel modules.Methods The system consists of a mother board,a control board and a data acquisition(DAQ)system.The mother board provides necessary resources including power supplies and the fanout of calibration signals.Besides,it can be used to test the connectivity by monitoring the power states.The control board reads data out and provides the clock,trigger and configuration data for the silicon pixel module.The DAQ system sends the control commands and receives the readout data through an Ethernet link.Results Compared with the previous readout system,this designed system has a lower noise level and better scanning curves making the calibration more accurate.And it has been successfully applied to the comparison experiments of the through silicon via and wire-bonding silicon pixel modules.Conclusion The results show that this test system can be used to the quality test and calibration of the silicon pixel modules.In addition,the system can be adapted to the measurement of different pixel array detector modules.

Influence of cryogenic permanent magnet undulator motion error on magnetic field error and radiation intensity loss

A cryogenic permanent magnet undulator prototype designed for Chinese High Energy Photon Source Test Facility(HEPSTF)at Institute of High Energy Physics is constructed and now commissioning.Motion precision of girders is a significant parameter to guarantee gap error so as to avoid phase error and radiation intensity loss.In order to study and minimize girder parallelism errors,RADIA and SPECTRA are used to calculate qualified motion precision.Spring Modules and single motor closed-loop feedback are designed to compensate the errors.Magnetic field is finally tuned to reach specifications.Details of the study and analysis will be presented in this paper.