A Method of Range Walk Error Correction in SiPM LiDAR with Photon Threshold Detection

A silicon photomultiplier (SiPM) LiDAR with photon threshold detection can achieve high dynamic performance. However, the number fluctuations of echo signal photons lead to the range walk error (RWE) in SiPM LIDARs. This paper derives the RWE model of SiPM LiDAR by using the LiDAR equation and statistical property of SiPM’s response. Based on the LiDAR system parameters and the echo signal intensity, which is obtained through the SiPM’s photon-number-resolving capability, the RWE is calculated through the proposed model. After that, we carry out experiments to verify its effectiveness. The result shows that the method reduces the RWE in TOF measurements using photon threshold detection from 36.57 cm to the mean deviation of 1.95 cm, with the number of detected photons fluctuating from 1.3 to 46.5.

The ABALONE photosensor

The ABALONE is a new type of photosensor produced by PhotonLab, Inc. with cost effective mass production, robustness and high performance. This modern technology provides sensitivity to visible and UV light, exceptional radio-purity and excellent detection performance in terms of intrinsic gain, afterpulsing rate, timing resolution and single-photon sensitivity. For these reasons, the ABALONE can have many fields of application, including particle physics experiments, such as DARWIN, and medical imaging. This new hybrid photosensor, that works as light intensifier, is based on the acceleration in vacuum of photoelectrons generated in a traditional photosensor cathode and guided towards a window of scintillating material that can be read from the outside through a silicon photomultiplier. In this work we present the simulation of the ABALONE and the results from operation at room temperature. The goal of the characterization is the evaluation of the gain, the response in time and the single photoelectron spectrum as a function of the electric field and the photoelectron emission angle. Details of future tests will be also discussed.

The diffraction detector for the EMD of the CSNS

On 23rd August 2018, the China Spallation Neutron Source (CSNS) located in Dongguan operated 4 neutron instruments. In the future, twenty neutron spectrometers will be built to provide multidisciplinary platforms for scientific research by national institutions, universities, and industries. Engineering Material Diffractometer (EMD), which will be used for strain measurements in engineering materials and components, will be constructed at the Beamline 8 in 2022. A novel thermal neutron detector, which will comply with the requirements of EMD application, is being developed. This detector will consist of 6LiF/ZnS(Ag) scintillation screens, wavelength shifting fiber (WLSF) arrays, a silicon photomultiplier (SiPM) and Application Specific Integrated Circuit (ASIC) read-out electronics. Each scintillation screen will be inclined with respect to the incident neutron beam at a grazing angle θ = 17°. Such geometry will not only improve the spatial resolution of detectors but also the neutron detection efficiency. The prototype of detector module has been tested at the neutron Beamline 20 at the CSNS. The experimental results obtained for this prototype illustrate that the pixel size of detector module is 3 mm and the detection efficiency exceeds 40% at the neutron wavelength of 1 Å. Based on these results, we design and manufacture the final version of the detector for the EMD application, which is characterized by low power consumption, highly integrated and easy to install. 70 such detectors will be installed till the end of 2021.

Method For Measuring Sub-Micron Facula At Single-Photon Level With Silicon Photomultiplier

Sub-micron faculae (light spots) at the single-photon level have important applications in many fields. This report demonstrates a method for measuring facula size at the sub-micron single-photon level indirectly. The developed method utilizes Silicon Photomultipliers (SiPMs) as the single-photon response detectors, combined with a nano-positioning stage. The approach involves one- or two-dimensional space scanning and a deconvolution operation, which enable evaluations of the size and spatial distribution of focused facula in a single-photon-level pulsed laser. The results indicate that the average full width at half maximum of the faculae is about 0.66 µm, which is close to the nominal resolution of the objective lens of the microscope (0.42 µm). The proposed method has two key advantages: (1) it can measure sub-micron facula at the single-photon level, and (2) the sub-micron facula can easily be aligned with the detector because the array area of the avalanche photodiode cells in SiPM is usually larger than one square millimeter, and there is no need to put an optical slit, knife edge, or pinhole in front of the detector. The method described herein is applicable in weak light facula detection related fields.