Method for fast determination of the angle of ionizing radiation incidence from data measured by a Timepix3 detector

This paper presents a method of how to determine spatial angles of ionizing radiation incidence quickly, using a Timepix3 detector. This work focuses on the dosimetric applications where detectors and measured quantities show significant angle dependencies. A determined angle of incidence can be used to correct for the angle dependence of a planar Timepix3 detector. Up until now, only passive dosemeters have been able to provide a correct dose and preserve the corresponding incidence angle of the radiation. Unfortunately, passive dosemeters cannot provide this information in “real” time. In our special setup we were able to retrieve the spatial angles with a runtime of less than 600 ms. Employing the new Timepix3 detector enables the use of effective data analysis where the direction of incident radiation is computed from a simple photon event map. In order to obtain this angle, we combine the information extracted from the map with known 3D geometry surrounding the detector. Moreover, we analyze the computation time behavior, conditions and optimizations of the developed spatial angle calculation algorithm.

Validation activities for the Ice, Cloud, and Land Elevation Satellite - 2 (ICESat-2) Mission

<p>After launching on 15 September 2018, the Ice, Cloud, and Land Elevation Satellite – 2 (ICESat-2) Mission began collecting data on 14 October 2018.  The mission uses green laser light emitted by the Advanced Topographic Laser Altimetry System (ATLAS) to detect individual photons that are reflected by the Earth’s surface and returned to ATLAS.  These photons, when combined with information on the pointing direction, and position of the observatory in space, provide a geolocation and elevation for every measurement that spans the globe from 88 degrees north latitude to 88 degrees south.  The Global Geolocated Photon data product provides a latitude, longitude, elevation, and measurement time for each photon event telemetered to Earth for each of the instrument’s six beams. This product also delineates between high, medium, and low signal confidence levels and those measurements associated with background noise. The higher level, along-track products each use different strategies for photon aggregation to optimize the precision and accuracy of the surface retrievals over specific surface types. These types include land ice, sea ice, vegetation/land, ocean, and inland water. There is a separate channel dedicated to atmospheric returns to measure cloud and aerosols over a vertical window of 15 km. Calibration efforts utilized well designed on-orbit maneuvers to identify both pointing and range biases attributed to orbital variations on the satellite. Once corrected, the science-quality data products were released to the public in May 2019.</p><p> </p><p>In this presentation, we will present our ongoing work to evaluate and validate the geolocation and elevation accuracy and precision of measurements provided by the ICESat-2 mission.  The approaches are diverse in both location and methodology to ensure that we have a comprehensive assessment of the ATLAS performance variations throughout the orbital cycles. These strategies include comparisons with ground-based and airborne elevation measurements over the ice sheets, detailed analysis of returns from well-surveyed corner cube retro-reflectors, comparison of sea ice freeboard measured by airborne lidars, evaluation of global-scale ocean elevation through comparison with radar altimeters, and comparison of vegetation canopy height metrics measured by airborne lidar.  Our work to date demonstrates that individual photon elevations are accurate to approximately 30 cm vertically, and 6 m radially.  Aggregating many photons together reduces the elevation uncertainty to less than 5 cm for relatively flat and smooth ice sheet interiors.</p>

Photon event evaluation for conventional pixelated detectors in energy-dispersive X-ray applications

We analyze and compare 6 different approaches for evaluating energy and position of single X-ray photons detected with conventional pixelated detectors.

Development of Data Acquisition Methods for an FPGA-Based Photon Counting Detector

MCP-based detectors are widely used in the ultraviolet (UV) region due to their low noise levels, high sensitivity and good spatial and temporal resolution. We have developed a compact near-UV (NUV) detector for high-altitude balloon and space flights, using off-the-shelf MCP, CMOS sensor, and optics. The detector is designed to be capable of working in the direct frame transfer mode as well in the photon counting mode for single photon event detection. The identification and centroiding of each photon event are done using an FPGA-based data acquisition and real-time processing system. In this paper, we discuss various algorithms and methods used in both operating modes, as well as their implementation on the hardware.

SIMULATION STUDIES OF TRIGGER DECISION CRITERION FOR THE ALICE/PHOS

This paper gives some results about trigger decision criterion of the ALICE PHOton Spectrometer (PHOS) by Monte Carlo simulations, including four parts: (1) an overview of trigger decision criterion of PHOS; (2) the energy reconstruction performance of PHOS; (3) the selection of trigger threshold and the event trigger efficiency distribution; (4) the photon event trigger rate of PHOS in p – p interactions and Pb – Pb collisions.