High-speed performance self-powered short wave ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)

High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.

Development of robust perovskite single crystal radiation detectors with high spectral resolution through synergetic trap deactivation and self-healing

Organic-inorganic halide perovskite single crystals(SCs)are promising materials for detecting ionizing radiation owing to their outstanding photoelectric conversion capability and inexpensive solution processability.However,the accuracy and stability of the detectors have been limited due to the charge traps and defects in SCs,especially when operated under high-precision photon-counting mode for energy spectrum acquisition.Here,we proposed a trap freezing deactivation route,which obviously suppressed dark current and noise by up to 97%and 92%,respectively.Furthermore,the bulk ion migration effect was essential for the ability to instantly self-heal defects induced by radiation damage at temperatures down to30C.Consequently,the detector exhibits a record high energy resolution of 7.5%at 59.5 keV for 241Amγ-ray source,which is the best solution-processed semiconductor radiation detectors at the same energy range.In addition,the detector maintains over 90%of its initial performance after 9 months of storage when tested in the air.Our results will represent a revision of the paradigm that high-spectral-resolution and robust radiation detectors can only be realized with high temperature grown inorganic semiconductor single crystals.

A review on emerging materials with focus on BiI_(3) for room-temperature semiconductor radiation detectors

Purpose Considerable advances in the fundamental knowledge and applications of radiation science have led to significant progress and development of room-temperature semiconductor radiation detectors(RTSD).The RTSDs technologies are continuously evolving with accelerated research and material engineering in the last decade.Significant scientific and technological advancements have led to development of high-performance radiation detectors with high signal-to-noise ratio(SNR),better sensitivity,faster response and higher-resolution with capability of desired room-temperature operation.This paper is a review on emerging semiconductor radiation detector materials with a deeper insight into the prospective role of Bismuth tri-iodide(BiI_(3))for room-temperature radiation detectors.Methods An introduction of the state of art of most developed semiconductor materials,i.e.,cadmium telluride(CdTe),mercury iodide(HgI_(2)),lead iodide(PbI_(2)),etc.,and a critical examination of properties,shortcomings and challenges related to their synthesis have been elaborated.Polymer-semiconductor composites with desirable properties and their integration into detector devices is also presented.Subsequent sections discuss the role of BiI_(3) as an emerging radiation detector material for room-temperature operation with an in-depth discussion on the role of defects in charge transportation and electrode configuration.Furthermore,the current challenges along with the future prospects of these materials for radiation detection to promote continuous innovation and practical applications are also elaborated.Conclusion The comprehensive review on latest developments in room-temperature radiation detector materials is expected to help establish a technological roadmap for the synthesis,fabrication and commercialization of novel materials for development of efficient radiation detectors.

Energetic particles’fluxes and dose in the Radiation Gene Box measured by space radiation detector onboard SJ-10 satellite

Background To evaluate the hazard of space radiation posing to the tissues,it is important to obtain exact fluxes of different radiation particles.The Radiation Gene Box(RGB)onboard SJ-10 spacecraft was an instrument designed to investigate the effects of space environment on the mESCs and drosophila.To derive the dose received by the tissues inside the RGB,the Space Radiation Detector(SRD)was installed inside it.Purpose The SRD was designed to derive the fluxes of electron,proton,hellion and gamma rays around it.If the type of the particles,the energies,the fluxes and the conversion coefficients are known,the dose received by the tissues could be evaluated.Methods The SRDwas designed as a △E-E solid-state telescope.By measuring the energy deposited in the three subdetectors,the particles’type and their energies could be discriminated.The data of SRDwere divided into 15 bins by the types of particles and their energy ranges.Results The gamma ray flux was higher than any other particle flux inside the RGB,and the electron was the most intense charge particle,while the helium ion was the most harmful radiation to the cells inside the RGB.Conclusion The dose rate inside the Radiation Gene Box was much higher than in the ground,but the integral dose of 12 days inside the RGB was about 2.13 mSv.It seemed unlikely to have obvious biological effects on the tissues of mice and drosophila.

Characterization of CdMnTe radiation detectors using current and charge transients

Charge transport characteristics of Cd_（0.95）Mn_（0.05）Te：In radiation detectors have been evaluated by combining time resolved current transient measurements with time of flight charge transient measurements.The shapes of the measured current pulses have been interpreted with respect to a concentration of net positive space-charge, which has resulted in an electric field gradient across the detector bulk.From the recorded current pulses the charge collection efficiency of the detector was found to approach 100%.From the evolution of the charge collection efficiency with applied bias,the electron mobility-lifetime product ofμ_nτ_n =（8.5±0.4）×10^（-4） cm^2/V has been estimated.The electron transit time was determined using both transient current technique and time of flight measurements in the bias range of 100-1900 V.From the dependence of drift velocity on applied electric field the electron mobility was found to beμ_n =（718±55） cm^2/（V·s） at room temperature.

Preparation of a silicon micro-strip nuclear radiation detector by a two-step annealing process

The annealing process for boron implantation is a crucial step during large size nuclear radiation detector fabrication. It can reduce the lattice defects and the projection straggling. A two-step annealing process for boron implantation was developed instead of a one-step annealing process, and the reverse body resistance of a silicon micro-strip detector was significantly increased, which means that the performance of the detector was improved.

Side-On transition radiation detector(TRD)based on THGEM

Purpose The characteristic that TR energy is proportional to the Lorentz factor provides a way for energy calibration.The High Energy cosmic-Radiation Detection calorimeter can be calibrated in space by the TRD in the future.Method In order to make the TR signal stand out from the energy loss signal,a new prototype of TRD called Side-On TRD with THGEM has been built.Side-on TRD uses side window incidence and strip readout to reduce the ionization energy registered in the channel where the TR photons are located,which is supposed to improve the detection efficiency of TR.Result and conclusion The Side-On TRD has been tested at CERN SPS and found the experimental results are significant.

Design and development of multi-channel front end electronics based on dual-polarity charge-to-digital converter for SiPM detector applications

With the development of silicon photomultiplier(SiPM)technology,front-end electronics for SiPM signal processing have been highly sought after in various fields.A compact 64-channel front-end electronics(FEE)system achieved by fieldprogrammable gate array-based charge-to-digital converter(FPGA-QDC)technology was built and developed.The FEE consists of an analog board and FPGA board.The analog board incorporates commercial amplifiers,resistors,and capacitors.The FPGA board is composed of a low-cost FPGA.The electronics performance of the FEE was evaluated in terms of noise,linearity,and uniformity.A positron emission tomography(PET)detector with three different readout configurations was designed to validate the readout capability of the FEE for SiPM-based detectors.The PET detector was made of a 15×15 lutetium–yttrium oxyorthosilicate(LYSO)crystal array directly coupled with a SiPM array detector.The experimental results show that FEE can process dual-polarity charge signals from the SiPM detectors.In addition,it shows a good energy resolution for 511-keV gamma photons under the dual-end readout for the LYSO crystal array irradiated by a Na-22 source.Overall,the FEE based on FPGA-QDC shows promise for application in SiPM-based radiation detectors.

Low-power SiPM readout BETA ASIC for space applications

The BETA application-specific integrated circuit(ASIC)is a fully programmable chip designed to amplify,shape and digitize the signal of up to 64 Silicon photomultiplier(SiPM)channels,with a power consumption of approximately~1 mW/channel.Owing to its dual-path gain,the BETA chip is capable of resolving single photoelectrons(phes)with a signal-to-noise ratio(SNR)>5 while simultaneously achieving a dynamic range of~4000 phes.Thus,BETA can provide a cost-effective solution for the readout of SiPMs in space missions and other applications with a maximum rate below 10 kHz.In this study,we describe the key characteristics of the BETA ASIC and present an evaluation of the performance of its 16-channel version,which is implemented using 130 nm technology.The ASIC also contains two discriminators that can provide trigger signals with a time jitter down to 400 ps FWHM for 10 phes.The linearity error of the charge gain measurement was less than 2%for a dynamic range as large as 15 bits.

Determination of Shallow Impurity Concentration in Detector-grade Silicon by FT-IR Spectroscopy at 4.2K

A Nicolet-200SXV FT-IR spectrometer combined with an exciting light set-up has been applied to determine the shallow impurity concentration in detector-grade silicon. The detection sensitivity of boron concentration is high up to 7.8 × 10-12. The calibration curve of boron concentration in high-purity silicon has been obtained, from which the experimental value of calibration factor of boron concentration in silicon is demonstrated to be 1.15 × 1013 cm-1.

Advances in nuclear detection and readout techniques

“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the universe.Also,they are being increasingly used in other disciplines like nuclear power generation,life sciences,environmental sciences,medical sciences,etc.The article reviews the short history,recent development,and trend of nuclear detection and readout techniques,covering Semiconductor Detector,Gaseous Detector,Scintillation Detector,Cherenkov Detector,Transition Radiation Detector,and Readout Techniques.By explaining the principle and using examples,we hope to help the interested reader underst and this research field and bring exciting information to the community.

Effect of Hydrostatic Pressure on Optical Properties of TlBr and TlCl

We present first principles calculations of optical properties of binary semiconductor compounds TlBr and TlCl.Dependences of dielectric function,reflectivity and refractive index on hydrostatic pressure are calculated using self-consistent scalar relativistic full potential linear augmented plane wave method(FP-LAPW) within a generalized gradient approximation(GGA).They are compared with previous calculations and experimental measurements.Good agreements are found.

坩埚下降法生长BSO(Bi_4Si_3O_(12))闪烁晶体

While the light output of BSO crystals is only 20% of the output of currently used BGO(Bi 4Ge 3O 12 )scintillation crystals,the decay time is one third(100ns).It is considered as promising for application as radiation detectors for high energy physics experiments.Based on this advantage,we have been proceeding with our development of large crystals to use practically.In this paper,we will review our results of crystal growth of BSO by Bridgman method and characterization on its scintillation performance. High purity raw materials of Bi 2O 3 and SiO 2 were mixed together,fired at 850℃,re mixed and sintered at 950℃.The charge was then fed into a Pt crucible of 25mm in diameter.For crystal growth,the crucible was lowered at 0.5mm/h in a furnace temperature gradient of about 10℃/cm.

Scintillation Characteristics of CsI Crystal Doped Br under Gamma and Alpha Particles Excitation

Inorganic scintillators play an important role in detection and spectroscopy of gamma, X-rays and alpha particles as well as neutrons and charged particles. Scintillation crystals based on cesium iodide (CsI) are matters with relatively low hygroscopicity, high atomic number, easy handling and low cost, characteristics that favor their use as radiation detectors. In this work, pure CsI crystal and bromine doped CsI crystals were grown using the Bridgman technique. The concentration of the bromine doping element (Br) was studied in the range of 1.5 × 10-1 M to 10-2 M. The distribution of the doping element in the crystalline volume was determined by neutron activation. The result obtained with neutron activation analysis (NAA) has found that the mean values of Br found in grown crystals are consistent with those introduced in salt CsI, showing the incorporation of Br in the matrix structure of CsI. The optical transmittance assays were performed at a wavelength range of 110 nm to 1100 nm. Analyses were carried out to evaluate the developed scintillators, concerning alpha particles and gamma radiation.

Application of stratified implantation for silicon micro-strip detectors

In the fabrication of a 48 mm×48 mm silicon micro-strip nuclear radiation detector with 96 strips on each side, a perfect P-N junction cannot be formed consistently by the one-step implantation process, and thus over 50% of strips produced do not meet application requirements. However, the method of stratified implantation not only avoids the P region between the surface of wafers and the P＋ region, but also overcomes the shadow effect. With the help of the stratified implantation process, a perfect functional P-N junction can be formed, and over 95% of strips meet application requirements.

Electrical and γ-ray energy spectrum response properties of PbI_2 crystal grown by physical vapor transport

Lead iodide single crystal was grown by physical vapor transport method.Two radiation detectors with different configurations were fabricated from the as-grown crystal.The electrical and y-ray response properties at room temperature of the both detectors were investigated.It is found that the dark resistivity of the detectors are respectively 3×10^（10）Ω·cm for bias electric field parallel to crystal c-axis（E//c） and 2×10~8Ω·cm for perpendicular to crystal c-axis（E⊥c）.The energy spectrum response measurement shows that both detectors were sensitive to ^（241） Am 59.5 keVγ-rays,and achieved a good energy resolution of 16.8%for the E⊥c-axis configuration detector with a full width at half maximum of 9.996 keV.