Detector Characteristics Research Articles

Development and characterization of fission chamber neutron detectors in Isfahan miniature neutron source reactor

In this research, two fission chamber neutron detectors have been designed and constructed, and their performance has been evaluated in the radiation field of the Isfahan miniature reactor neutron beam line. Each detector consists of two coaxial cylinders called anode and cathode made of stainless steel. The outer layer of the anode is covered with a very thin layer of uranium-235 oxide as fissile material, and a mixture of argon and nitrogen gas is used as the filling gas. The thickness of the deposited layer on the anode is different, so that on one of them, named FC400A, the thickness of the uranium oxide layer was more than 5 μm, and on the other one, named FC400B, it was less than 1.5 μm. A spectrum collection software has also been designed and developed in LabVIEW. The developed detectors are irradiated in the neutron field resulting from the neutron radiography beamline of the miniature neutron source reactor in the range of neutron flux of about 2E+02 to 2E+05 n.cm−2.s−1. In order to determine the sensitivity of the detection response, the results of these two detectors are also compared with a commercial fission chamber neutron detector. The results showed that the working voltage range of these detectors is in the range of 400–600 V and both of these detectors have a suitable linear response in the mentioned neutron flux range. Also, the sensitivity of FC400A and FC400B detectors is 0.1 and 1 counts/1E+04 neutrons, respectively.

Electronic gain study of single resistive electrode thick electron multiplier (RETGEM) radiation detectors with various resistive layers and substrates in P-10 gas

The study of resistive electrode thick gas electron multipliers (RETGEMs) of various designs is described. Four types of RETGEMs were tested. One was made of a substrate of a flame-retardant glass epoxy FR4 board coated with graphite as a resistive layer. The second was made of an FR4 board laminated with Kapton as a resistive layer. The third was made of a polyvinyl chloride (PVC) board coated with graphite as a resistive layer. Finally, a RETGEM with a diamond-like carbon coating produced by CERN was also tested. Multiple characteristics of the single RETGEM detector, such as absolute gas gains and maximum applicable voltages, were measured for all four types of RETGEMs at various voltages applied to the RETGEMs and various sizes of induction gaps, using Cm-244 alpha and F-55 X-ray sources. The results have shown that the highest absolute gas gain is achieved with the FR4 board laminated with Kapton. On the other hand, the PVC board coated with graphite gives the minimum voltage at which the signal can still be observed.

Use of CdZnTe Quasi-Hemispherical Detectors under the Impact of Low Temperatures and High-Gamma Radiation Fluxes.

This article discusses the possibilities and limitations of CdZnTe (CZT) quasi-hemispherical detectors operating over a wide temperature range and at high-gamma radiation fluxes. The results of the negative influence of low- and high-operating temperatures, as well as high-radiation fluxes on spectrometric characteristics of CZT detectors and possible ways to eliminate performance deterioration, are presented. The impact of infrared (IR) illumination parameters, such as wavelength and irradiation intensity on the spectroscopy performance of detectors, was investigated. A correctly chosen IR illumination wavelength and intensity were shown to significantly improve the energy resolution of CZT quasi-hemispherical detectors, allowing their stable operation in high-gamma radiation fluxes and extend the operating temperature range toward low temperatures. The influences of bias voltage values and temperatures on the quasi-hemispherical CZT detectors' operating ability at high-gamma radiation fluxes were studied.

Characteristics of the new Photon counting CT detector

Radiology is one of the fastest growing branches of medicine, and precisely one of the devices that follows this development the fastest is the computerized tomography device. Scientists are most focused on research into improving the parameters of the X-ray tube and detector as the most important parts of this imaging modality. In addition to the detector with energy integration, which is widely used today as part of everyday clinical practice, the subject of research is also a Photon countng detector. The numerous virtues that stand out in the new type of detector are responsible for the general opinion that in the future this new technology will dominate CT devices in clinical practice, improving the acquisition of numerous diagnostic and interventional procedures. It is believed that this technology ushers radiology into a new era precisely with its improved spatial and contrast resolution, noise reduction and increase of contrast to noise ratio, but also with new possibilities such as simultaneous imaging of multiple contrast agents and multi-energy imaging. Improvements in the visibility of iodine contrast agent provide additional diagnostic possibilities and more accurate differentiation of benign and malignant suspected lesions. The significantly smaller pixel size on this detector offers an almost two-fold increase in spatial resolution, and thus an increase in radiation dose efficiency. The use of a detector with a photon counter is therefore also suitable for pediatric patients, and there is also a wide range of low-dose imaging options for the purpose of preventive cancer screening. Processes such as the material decomposition and spectral imaging are still in the research process, but have great potential to optimize future daily clinical practice. More work and published research results are needed, but surely this technology will one day make the work of radiologic technologists and radiologists easier.

Synchrotron radiation of a single electron application for optical spectroradiometry

Objectives. The investigations of optical radiation sources and metrological detector characteristics in the infrared (IR), visible, and air ultraviolet (UV) spectral regions are partially based on the unique metrological properties of synchrotron radiation. The aim of this work is to develop a high-precision method for determining the storage ring accelerated electron number with synchrotron radiation of a single electron to establish spectroradiometry and photometry units.Methods. By determining the number of accelerated electrons, any storage ring can be used to calculate the synchrotron radiation characteristics at wavelengths of many large then the critical wavelength in the visible, air UV, and IR regions of the spectrum. This makes it possible to determine the main metrological characteristics normalized to the number of electrons, such as luminous intensity, luminance, illuminance, radiant power, radiance, irradiance, etc., regardless of the energy of the electrons.Results. When applying the method for determining the number of accelerated electrons at low currents of the electronic storage ring, a total standard deviation of the number of accelerated electrons is less than 0.01% for an exposure range of the CCD matrix from 10−2 to 3 · 103 s in a wide dynamic range of 1−1010 electrons per orbit.Conclusions. The use of a CCD-based radiometer-comparator calibrated by responsivity on a synchrotron radiation source is particularly relevant in monitoring luminance contrast thresholds and spatial distribution of object and background brightness, as well as determining metrological characteristics of optoelectronic measuring instruments, including CCD cameras, radiometers, spectroradiometers and photometers.

Impact of Measurement Conditions and Design Features of IBA Detectors on the Small Radiation Fields Output Factors

The use of modern diagnostic equipment in oncology has made it possible to detect small tumor foci, as
 well as to detect distant metastases of the disease at an early stage of their formation. In these cases, it
 becomes possible to refuse surgical interventions, replacing them with stereotactic radiosurgery using
 radiation therapy devices. In this case, small irradiation fields can be used (from fields less than 1 cm to
 4 cm). In such cases, there is a problem of delivering large doses to small foci. It consists in the accuracy of determining the absorbed doses delivered to small targets. The complexity of monitoring the quality of dosimetric support of irradiation with the use of various radiotherapy devices is increasing. Increased requirements are also imposed on the detectors used for measurements.
 This work has several goals:
 1) to study the results of measurements of the output factors using five different detectors of small
 sizes;
 2) to determine the changes in the output factors when using two types of beam collimation (collimator
 shutters - JAWS and multileaf collimator - MLC) of linear electron accelerators;
 3) to study the dependence of the output factors on the source-to-surface distance (SSD), on the depth
 of measurements and on the type of detectors.
 The measurements were carried out in 6 MV photon beams with a flattening filter on a TrueBeam linear
 accelerator. Five IBA detectors were used: two diode detectors (PFD and SFD) and three ionization
 chambers (CC01, CC04 and CC13). The field sizes varied from 1010 cm to 11 cm. The studies were
 carried out for the following combinations of parameters: SSD is 100 cm and the measurement depth is
 10 cm; SSD is 95 cm and the measurement depth is 5 cm. The fields were formed by JAWS and MLC.
 The analysis of the obtained results made it possible to compare the data obtained from each detector
 in similar combinations of measurements. Based on the analysis of the output factors measured by all
 five detectors, conclusions were drawn about the parameters that affect the change in the output factors.

Radiation hardness characteristics of self-powered detector based on SiC/Si heterojunction diode

Radiation hardness characteristics of self-powered detector based on SiC/Si heterojunction diode

Characteristics of thin p-MCz Si Microstrip Detector Irradiated upto a mixed fluence of 1017neq./cm2for the FCC

Silicon microstrip detectors can be used for the precise particle tracking in the inner tracking region of the detector used in the future high luminosity collider experiment. In the future experiments, hadron collider provides higher luminosities on the strip detector, and therefore, a detector requires very high radiation hardness. Within CERNRD50collaboration, MCz Si is identified as a prime radiation hard material for the fabrication of the p-Si microstrip detector. In this paper, we have used the experimentally verified four level deep-trap mixed irradiation model for p-MCz Si to investigate the effect of heavy irradiations up to a mixed fluence of 1017n eq./cm2 on the full depletion voltage, leakage current, and charge collection efficiency using SRH and CCE modelling.The changes in the characteristics were evaluated, and effect of the traps on the macroscopic performance of the detectors and possible improvement in the design and semiconductor technology of the p-Mcz silicon microstrip detector.

Generalized Decoy-State Scheme for Rigorous Characterization of Single-Photon Detectors

Generalized Decoy-State Scheme for Rigorous Characterization of Single-Photon Detectors

Cryogenic phonon-detector model with solid argon for detecting dark matter* *This work is supported by the National Key Research and Development Program of China (2017YFA0402203) and the National Natural Science Foundation of China (12075161)

Over the past few years, phonon detectors have emerged as a prevailing technology for detecting low-mass dark matter due to their low thresholds and high resolution. These detectors, which employ either dual-phase detectors combining phonon-light or phonon-electron interactions, have significantly advanced direct dark matter detection efforts. Argon, as a low-background and high-reserve detection medium, has also played a crucial role in this field. Both liquid-argon single-phase detectors and gas-liquid two-phase time projection chambers (TPCs) have contributed substantially to the direct detection of high-mass dark matter. By integrating these distinct detector types, the upper limits of the corresponding mass cross-section in dark matter detection can be lowered. We propose a phonon detector utilizing solid argon as the absorber, which combines the advantages of both aforementioned detector types. However, due to the requirement for an ultra-low temperature environment in the tens of millikelvin (mK) range, experimental investigations of solid argon phonon detector performance are currently constrained by technical limitations. Therefore, the performance analysis of the solid argon phonon detector presented in this study is only based on sapphire phonon detectors. Although there may be discrepancies between this approximation and the actual performance, the intrinsic characteristics of phonon detectors permit a qualitative evaluation of the solid argon phonon detector's potential capabilities.

Low-background experiment to search for double beta decay of 106Cd using 106CdWO4 scintillator

An experiment to search for 2ε-, εβ+- and 2β+-decays of 106Cd, using a 215 g cadmium tungstate scintillation crystal enriched at 66 % by 106Cd (106CdWO4) is carried out at the Gran Sasso underground laboratory (Italy). Events in the 106CdWO4 detector are recorded in (anti)coincidences with two large-volume CdWO4 scintillation counters. The design of the detector system, calibration and background measurements, methods, and results of data analysis to determine key detector characteristics are described. The experimental data are compared with Monte Carlo simulation results, and a background model is constructed. The radioactive contamination of the setup components is studied. The sensitivity of the experiment approaches the level of theoretical predictions for the 2νεβ+-decay channel, while for other possible 2β-decay channels it is already on the level of lim T1/2 ∼ 1021-1022 years.

Analysis of signal waveform from a midsize liquid argon detector

The midsize single-phase liquid argon prototype detector, operating at the surface laboratory, is designed to measure scintillation light emitted by the liquid argon (LAr). The detector employs 42 8-inch photomultiplier tubes (PMT) to collect the light. By analyzing the waveform of the signal, important detector characteristics such as the slow decay time constant that characterizes the purity of the liquid argon can be obtained. To describe the signal waveform, a model, which takes into account the liquid argon emission decay times together with the TPB re-emission process as well as the signal reflection effects, is used. The TPB re-emission process is introduced using a three-exponential time structure. Additionally, experimental results provide comprehensive validation for a post-peak hump structure, which is attributed to signal reflection.

Analysis of the Response Characteristics of Smoke and Carbon Monoxide in Non-Fire Conditions

This study confirms the applicability of cross-detection by analyzing the response characteristics of smoke and carbon monoxide detectors, to reduce non-firm alarms. Based on the results of previous studies, various scenarios reflecting non-fire conditions in Korea were selected, to conduct experiments to confirm the change in carbon monoxide concentration and the response of smoke detectors based on the measurement location. Although carbon monoxide was detected earlier than the smoke near the heating source, the smoke detector reacted earlier than the carbon monoxide meter as the distance from the heating source increased. The measured concentration of carbon monoxide was much lower than the concentration generated in the case of a fire, thus confirming the applicability of carbon monoxide cross-sensing for non-fire detection.

Thermal and optical characterization of a resistance-temperature detector based on platinum thin film: Design and fabrication

In this research, it is presented an easy-to-implement method, utilizing spin coating-sputtering technique, for the production of cost-effective resistance temperature detectors (RTDs) based on platinum (Pt). By employing physical patterning mask techniques such as lithography, the shape of RTDs can be readily customized to meet specific requirements. Furthermore, the developed Pt-based RTDs exhibit a higher sensitivity, with a temperature coefficient of resistance (α) approximately at 3.87 × 10−3 ◦C−1, compared to RTDs based on Au, Ag, and Cu. The sensitivity of these Pt-based RTDs is comparable to that of commercially available Pt-based sensors. Moreover, these RTDs demonstrate exceptional repeatability, maintaining consistent performance within a temperature range of up to 200 ◦C. According to interesting nonlinear optical findings, Pt-based RTD sensor showed the nonlinear optical responses in the 532 nm wavelength because of two photon absorption phenomena in nonlinear absorption coefficient (NLA) and self-focusing effect in addition to their excellent temperature sensing capabilities, the Pt-based RTDs exhibit notable nonlinear optical refractive index (NLR) and nonlinear absorption (NLA) properties. The NLR index of the RTDs is on the order of 10−8 cm2/W, while the NLA index is on the order of 10−3 cm/W. This implies that these RTDs possess significant nonlinear optical response characteristics. Moreover, the Pt-based RTDs demonstrate rapid response times to changes in temperature, making them suitable for applications in nonlinear optical equipment such as optoelectronics and photonics.

Virgo detector characterization and data quality: tools

Detector characterization and data quality studies—collectively referred to as DetChar activities in this article—are paramount to the scientific exploitation of the joint dataset collected by the LIGO-Virgo-KAGRA global network of ground-based gravitational-wave (GW) detectors. They take place during each phase of the operation of the instruments (upgrade, tuning and optimization, data taking), are required at all steps of the dataflow (from data acquisition to the final list of GW events) and operate at various latencies (from near real-time to vet the public alerts to offline analyses). This work requires a wide set of tools which have been developed over the years to fulfill the requirements of the various DetChar studies: data access and bookkeeping; global monitoring of the instruments and of the different steps of the data processing; studies of the global properties of the noise at the detector outputs; identification and follow-up of noise peculiar features (whether they be transient or continuously present in the data); quick processing of the public alerts. The present article reviews all the tools used by the Virgo DetChar group during the third LIGO-Virgo Observation Run (O3, from April 2019 to March 2020), mainly to analyze the Virgo data acquired at EGO. Concurrently, a companion article focuses on the results achieved by the DetChar group during the O3 run using these tools.

Virgo detector characterization and data quality: results from the O3 run

The Advanced Virgo detector has contributed with its data to the rapid growth of the number of detected GW signals in the past few years, alongside the two Advanced LIGO instruments. First during the last month of the Observation Run 2 (O2) in August 2017 (with, most notably, the compact binary mergers GW170814 and GW170817), and then during the full Observation Run 3 (O3): an 11 months data taking period, between April 2019 and March 2020, that led to the addition of 79 events to the catalog of transient GW sources maintained by LIGO, Virgo and now KAGRA. These discoveries and the manifold exploitation of the detected waveforms benefit from an accurate characterization of the quality of the data, such as continuous study and monitoring of the detector noise sources. These activities, collectively named detector characterization and data quality or DetChar, span the whole workflow of the Virgo data, from the instrument front-end hardware to the final analyses. They are described in detail in the following article, with a focus on the results achieved by the Virgo DetChar group during the O3 run. Concurrently, a companion article describes the tools that have been used by the Virgo DetChar group to perform this work.

Response characteristics of MAPbBr3 direct conversion X-ray detectors based on measurements and Monte Carlo simulation

In recent years, higher requirements have been placed on the response characteristics of X-ray detectors in the field of medical diagnostic imaging. Due to this, high sensitivity, high attenuation coefficient and low cost detection materials need to be developed. In this paper, the geometric model of a detector was established by Geant4 code. The absorption efficiency and mass attenuation coefficient of MAPbBr3 crystals were calculated in the energy range of 30 keV to 100 keV. Compared with the mass attenuation coefficient of the NIST database, the deviation was within 1.39%. The signal charge number and detection sensitivity of the X-ray interaction with the MAPbBr3 crystal ware calculated. Compared with the CdTe crystal and α-Se, the MAPbBr3 crystal still had a larger detection sensitivity under a smaller applied electric field, which was approximately 9 times higher than that of α-Se. This result indicated that the detection sensitivity could be greatly improved by using a high atomic number and high charge mobility-lifetime product. Based on the simulation results, the 2 mm thick MAPbBr3 crystal exhibited the highest detection sensitivity at 60 keV X-rays, which was in agreement with the experimental results.

Spectral and polarimetric characterization of the Gas Microchannel plate Pixel Detector

The Gas Microchannel plate Pixel Detector (GMPD) is used to measure X-ray polarization in astrophysical sources, and is the prototype of the Low Energy Polarimeter Detector (LPD) in the POLAR-2 project. The choice of the detector's gas mixture has a profound impact on its sensitivity to polarized X-rays. Here, we present the characteristics of the GMPD filled with a mixture of 40% He and 60%DME at 0.8 atm. Using Bragg diffraction, we generated nearly fully polarized and monochromatic X-rays at an angle of approximately 45°, and for the first time, we measured the modulation factor and spectral capability at energies of 2.98 keV, 4.51 keV, 6.40 keV, and 8.05 keV. The energy resolution measured is 18% at 6.40 keV, inversely proportional to the square root of the X-ray energy. The measured modulation factors were close to those obtained for the GPD developed by INFN-Pisa and INAF/IASF-Rome, reaching approximately 0.5 above 6 keV, allowing a comparison of the sensitivity of the GMPD and GPD.

Development and characterisation of high-resolution microcalorimeter detectors for the ECHo-100k experiment

The goal of the ECHo experiment is a direct determination of the absolute scale of the neutrino mass by the analysis of the end-point region of the 163Ho electron capture (EC) spectrum. The results of the first phase of the experiment, ECHo-1k, have paved the way for the current phase, ECHo-100k, which aims at a sensitivity below 2eV on the effective electron neutrino mass. In order to reach this goal, a new generation of high-resolution magnetic microcalorimeters with embedded 163Ho have been developed and characterised. The design has been optimised to meet all the challenging requirements of the ECHo-100k experimental phase, such as excellent energy resolution, wafer scale implantation and multi-chip operation with multiplexing read-out. We present the optimisation studies, the final design of the detector array and the first characterisation studies. The obtained results demonstrate that the detectors fully match and even surpass the requirements for the current experimental phase, ECHo-100k.

A 64k pixel CMOS-DEPFET module for the soft X-rays DSSC imager operating at MHz-frame rates

The 64k pixel DEPFET module is the key sensitive component of the DEPFET Sensor with Signal Compression (DSSC), a large area 2D hybrid detector for capturing and measuring soft X-rays at the European XFEL. The final 1-megapixel camera has to detect photons with energies between 250,text{eV} and 6,text{keV}, and must provide a peak frame rate of 4.5,text{MHz} to cope with the unique bunch structure of the European XFEL. This work summarizes the functionalities and properties of the first modules assembled with full-format CMOS-DEPFET arrays, featuring 512,times ,128 hexagonally-shaped pixels with a side length of 136 μm. The pixel sensors utilize the DEPFET technology to realize an extremely low input capacitance for excellent energy resolution and, at the same time, an intrinsic capability of signal compression without any gain switching. Each pixel of the readout ASIC includes a DEPFET-bias current cancellation circuitry, a trapezoidal-shaping filter, a 9-bit ADC and a 800-word long digital memory. The trimming, calibration and final characterization were performed in a laboratory test-bench at DESY. All detector features are assessed at 18,^{circ }text{C}. An outstanding equivalent noise charge of 9.8e−rms is achieved at 1.1-MHz frame rate and gain of 26.8 Analog-to-Digital Unit per keV (,text {ADU}/text{keV}). At 4.5,text{MHz} and 3.1,,text {ADU}/text{keV}, a noise of 25.5 e−rms and a dynamic range of 26,text{k}text {e}^{-} are obtained. The highest dynamic range of 1.345,text{M}text {e}^{-} is reached at 2.25,text{MHz} and 1.6,text {ADU}/text{keV}. These values can fulfill the specification of the DSSC project.