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A faster time performance can be achieved by focusing on prompt emitted photons, such as Cherenkov photons. In this study, the time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators were first simulated, and we evaluated the detector performance and discussed ways to improve the coincidence time resolution (CTR) results for the detector with the three radiators. Finally, we compared detection efficiency of Cherenkov radiation in three radiators. In this work, we recorded the step-by-step information of Cherenkov photons and the electrons that produced them in the radiator, information of photons on the photon outputting surface, and the step-by-step information tracing of the parent charged particles (electrons) to evaluate the factors influencing the performance time of the detector based on Geant4. Specially, we usually use a photon amplitude timing in the experimental implements, and the arrival time of an event is defined as the arrival time of the first photon of the event accordingly. The time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators with a 5 mm length were simulated as 28.5 ps for PbF, 40.1 ps for PbWO4, and 24.7 ps for Al2O3. After considering other factors such as quantum efficiency (QE) of 30% and transit time spread (TTS) of 10 ps from the process of practical electronics, the CTR of a pair of single-pixel detectors were 56.6 ps for PbF2, 78.8 ps for PbWO4, and 46.3 ps for Al2O3 with a thickness of 5 mm. The detection efficiency of PbF2 is 32.25%, PbWO4 of 31.91% and Al2O3 of 8.14% in the case of 5 mm length. The simulation results indicated that using the Cherenkov photons produced in PbF2, PbWO4, Al2O3 for detector timing can obtain good CTR results. In this study, it demonstrates that it is possible to achieve a pretty good CTR with an improved QE and a reduced TTS of the photodetector.

A 50 × 50 × 10 mm3 monolithic gadolinium aluminum gallium garnet (Gd3Al2Ga3O12; GAGG):Ce crystal coupled to a 8 × 8 silicon photomultiplier (SiPM) array was developed; it showed very good system uniformity and a high energy resolution of 7.4% at 662 keV. By using a convolutional neural network-based positioning algorithm and a fan-beam calibration method, the detector achieved a position resolution of ∼1.4 mm and a depth of interaction resolution of ∼2 mm. Based on this high-performance monolithic detector, we developed a coded aperture gamma camera. A 1-mCi Cs-137 source centered at a 2-m distance from the mask could be reconstructed with a signal-to-noise ratio of 6.5 in 1 s. Furthermore, the imaging ability of a low-energy Am-241 source and a low-activity Cs-137 source when the background-to-signal ratio was approximately 1:1 and a double low-activity source (Cs-137 and Na-22) was demonstrated. It is shown that the monolithic-crystal-based coded aperture gamma camera can achieve high performance and has a large potential for further improvement.

A self-supporting, 2-D, time-encoded aperture system was developed for both gamma and neutron imaging. The system achieved high sensitivity for imaging due to the use of an M–P array which has flat sidelobes of cross-correlation reconstruction and is self-supporting. It is demonstrated that a 24.4 μ Ci 137 Cs radiological point source could be detected within 10 min when the source-to-background ratio is 1:1. Several radiation scenes support that the system has an imaging capability of multipoint, extended, and gamma/neutron discrimination sources. The features of good cross-correlation decoding properties, panoramic imaging, and rapid reconstruction make such a system design attractive and prospective for the localization of radioactive hot spots.

This paper presents the results of the in situ absolute intensity calibration for the 32-channel heterodyne radiometer on the experimental advanced superconducting tokamak. The hot/cold load method is adopted, and the coherent averaging technique is employed to improve the signal to noise ratio. Measured spectra and electron temperature profiles are compared with those from an independent calibrated Michelson interferometer, and there is a relatively good agreement between the results from the two different systems.

In this paper, a tracking method for optoelectronic imaging platform of tethered balloon based on difference global positioning system/inertial navigation system is presented in detail. The location and attitude information of optoelectronic imaging platform, the azimuth and elevation angles of camera’s line of sight are used by this method to locate the ground target at the centre point of the camera’s field of view through corresponding coordinate transformation. And then, the method makes use of the update position and attitude information to solve the theoretical point of camera’s line of sight inversely. Finally, an angle control commend will be sent to the inertially-stabilized turntable on the optoelectronic imaging platform, which will adjust its azimuth and elevation angle to make the camera’s line of sight to the ground target. A lot of experiments are conducted, and the results show that the initial ground target is always in the centre of camera’s field of view no matter how the balloon’s position and attitude change, and the new location data of ground target has little difference with the initial location data, while the difference between them is close to 0.

A 32-channel heterodyne radiometer has been developed for the measurement of electron cyclotron emission (ECE) on the experimental advanced superconducting tokamak (EAST). This system collects X-mode ECE radiation spanning a frequency range of 104-168 GHz, where the frequency coverage corresponds to a full radial coverage for the case with a toroidal magnetic field of 2.3 T. The frequency range is equally spaced every 2 GHz from 105.1 to 167.1 GHz with an RF bandwidth of ~500 MHz and the video bandwidth can be switched among 50, 100, 200, and 400 kHz. Design objectives and characterization of the system are presented in this paper. Preliminary results for plasma operation are also presented.