In this work, we show the design and characterization of an image sensor with 64x64 pixels and its associated hardware and software needed to use the chip. The aim of the chip is to be used as a sensor for TEM electron microscopy. First measurements were done using X-Rays to characterize the chip and to test the whole system (ASIC, Software, and Hardware).
The here described sensor was...
The objective of this work was to evaluate UO2 as a solid-state direct-conversion neutron detector material by utilizing single crystal and thin films of UO2. Initial investigations indicated the material properties were unsuitable and efforts were made to enhance grain size and increase electrical resistivity by using dopant materials. Samples of arc-fused single crystal UO2 included that...
Diverging collimators are used to obtain reduced images of an object, or to detect a wide field-of-view (FOV) using a small gamma camera. In the gamma camera using the diverging collimators, the block scintillator, and the pixel scintillator array, gamma rays are obliquely incident on the scintillator surface when the source is located the periphery of the FOV. Therefore, the spatial...
The plasmaโs X-ray monitoring in Laser Produced Plasmas (LPPs) experiments is troublesome since the X-ray emissions impinge the detector in a too short time window (from a few tens of ps to few ns,) depending on the power and pulse time width of the laser. Hence the measure of the non-integrated photon flux is a problem hard to handle. To this end, we have used the Timepix3 (TPX3) chip, in a...
To handle the increasing number of cancer patients, China has built its own carbon ion therapy facility. The beam monitoring system in the therapy facility ensures the beam energy deposition can accurately cover the dedicated tumor region. The full image of the beam energy deposition is needed for accurate beam calibration, thus a Monolithic Active Pixel Sensor (MAPS), which can provide the...
Abstract
Silicon photomultipliers (SiPMs) are one of the modern instruments for nuclear physics detectors. Due to their excellent parameters near room temperature, these devices the best candidate to be used in the neutrino experiments such as nEXO, NEXT and DUNA, where the SiPMs should operate at sufficiently low temperature. This paper presents the results obtained with SiPMs from...
A high-performance charged particle spectrometer was developed for investigation of reactions induced by fast neutrons. The charge particle detector is a twin-gridded ionization chamber and its structure can be found in Ref. [1]. In this article, we describe experimental methods for detecting alpha particles using a twin-gridded ionization chamber developed at FLNP JINR using the PXI system,...
A new physical model of avalanche process with single photon detection capabilities is presented in this work. The new model describes development of avalanche process in time, taking into account the space charge resistance as well as the change of electric field in the avalanche region caused by internal discharge and external recharge currents. Results of simulations are compared with...
Metal Whiskering is a phenomenon occurring in electrical devices when whisker-like extrusions are forming from metal during the time, they look like small metal hairs or tendrils. This phenomenon was noticed in a vacuum tube for tin, and for other metals like zinc, cadmium and even lead. Whiskers growing between metal solder pads causing short circuits.
Investigation of the metal whiskering...
Recently, high resolution micrography became of great interest. Very thin scintillator layers of about 5-20 micrometers are used to achieve spatial resolution below one micrometer in application for low energy X-ray micro-radiography. Such thin screens are mainly used in micro-CT and nano-CT systems with either micro-focus X-ray tubes or with synchrotron sources.
This work deals with a high...
In this study, an organic polymer-based photodetector with a conjugated polymer PBDB-T1) and a non-fullerene ITIC2) was investigated to improve the sensitivity and frequency response for the indirect X-ray detection. The PBDB-T has more alkyl-chains and quinoids, so it can show better carrier transport than P3HT3) (commonly used donor). The chosen ITIC instead of PC70BM4) (commonly used...
In this paper, we examined the role of amorphous indium-gallium-zinc-oxide (a-IGZO) interfacial layer between PBDB-T1):PC70BM2) active layer and LiF/Al cathode to improve the sensitivity of indirect-type organic X-ray detector. According to the energy band diagram described in Fig 1a, the a-IGZO layer can block hole transport and also enhance electron transport from the active layer. Using a...
The heavy-ion experiments at the Heavy Ion Research Facility in Lanzhou (HIRFL) and the future High Intensity Heavy-Ion Accelerator Facility (HIAF) in China drives the development of high-performance particle imaging detectors. Due to the high spatial resolution, fast timing response and low noise level, a Monolithic Active Pixel Sensor (MAPS) is being developed with 130nm CMOS process for the...
Abstract
Contrast-enhanced dual-energy mammography (CEDM) is a promising approach for early breast cancer detection. In CEDM, two images could be acquired by using both double exposure with energy integration system or single exposure with energy resolved photon-counting (PC) system [1]. The PC systems are commonly consists of direct conversion X-ray sensors connected to application specific...
This paper presents the development of a prototype pixel readout ASIC for CZT detectors fabricated in a 180 nm CMOS process. It consists of a 32ร32 array of pixels in 100 um pitch and the EOC (end-of column) circuit for control and data readout. Each pixel integrates a charge sensitive preamplifier, a CR-RC shaper, two discriminators, two 12-bit counters and registers, allowing us to acquire...
Radiotherapy has the possibility of adverse reactions due to overlapping dose at skin surface binding parts. Exposure of the skin to 2 Gy or higher doses can cause adverse reactions such as erythema, desquamation, and necrosis. To prevent them, the skin dose is predicted through a treatment planning system, but its accuracy is only 50 ยฑ 25%. Thus, we need dosimeters that can accurately measure...
Dedicated dental cone-beam computed tomography (CBCT) examinations are being greatly increased for not only therapeutic but also cosmetic purposes. While, therefore, patient-specific dose management will be a great concern, the average dose measurement with a cylindrical phantom is the only method for the dose estimation in CT. However this standard CT dose index method is aimed at quality...
The conventional chest x-ray radiography suffers from a less conspicuity of soft tissue lesions (e.g. lung nodules) because of overlapping bone tissues. Digital tomosynthesis (DTS) or dual-energy imaging (DEI) may enhance the soft-tissue conspicuity by discriminating depth information or suppressing the bone tissues, respectively. However, DTS requires additional equipment and DEI would be...
The Compton scattering (CS) and the photoelectric effect (PE) accompanying fluorescence (FL) in semiconductor detectors can cause confused information about interaction locations. This implies signal spreading and increased correlation noise in resultant images. Escapes and reabsorptions of those secondary photons can further increase image noise. When the detector is operated in a...
In non-destructive x-ray inspection of a printed circuit board (PCB), the field of view (FOV) is usually small because of the application of high magnification into radiographs, which can help find micro-sized defects in ball-grid arrays or wire bonding parts. Without loss of FOV digital zooming can be applied, but which results in check-board artifacts at some extents of zooming level....
For the quality control of electronic products with high-density electronic packaging and corresponding multilayer printed circuit boards, x-ray inspection is not optional anymore. A combination of micro-focus x-ray source and fine-pixel high-resolution imaging detector is typical in industrial x-ray inspection systems for detecting micro-sized defects. This combination can further enhance...
Single-shot dual-energy imaging (DEI) using a sandwich-like multilayer detector is promising because it is immune to motion artifacts and it can relatively emphasize high-frequency contents [1]. Since the sandwich detector uses the beam-hardening difference between two detector layers for energy separation, the imaging performance is largely dependent on the detector design (i.e. scintillators...
SOI(Silicon On Insulator) based pixel detectors are promising as an scatterer in Compton imaging because of its thick sensitive area(~500 ยตm) and small pixel size up to less than 10 ยตm. SOI based electron tracking Compton camera are fabricated and tested in the previous study[1][2]. Electron tracking could improve the signal to noise ratio in the reconstructed image.One of the issues in...
Currently, semiconductors with high atomic number Z arouse strong interest in construction of sensors with X-ray spectrum. The most prospective materials are presented by elements from the group ะIIIBV. Gallium arsenide compensated with chromium (HR-GaAs:Cr) is one of these materials and exhibits unique characteristics. Sensors based on HR-GaAs:Cr demonstrate high efficiency. The response of...
Direct- and indirect-conversion detectors, which use a photoconductor and a scintillator, respectively, for detection of x-ray photons, compete to each other in diverse x-ray imaging fields. The spatial-resolution performance of the direct-conversion detector is generally known to be superior to that of the indirect-conversion detector. Structurization of the scintillator into pixel geometry,...
The electronic personal dosimeter (EPD) based on a 3ร3 mm2 PIN diode coupled to a 3ร3ร3 mm3 CsI(Tl) scintillator was designed for measuring an ambient dose equivalent (H*(10)). The designed EPD was capable of measuring H*(10) within the energy range of 40 keV to 2 MeV from the gamma spectroscopy. However, since the inorganic scintillator differs from human tissue, the energy response...
Abstract.
Nowdays, silicon photomultipliers are widely used as scintillation light readout in many scientific and commercial applications which one of interesting field is gamma spectroscopy. There are various types of SiPMs offered by different vendors. Among these SiPMs, a micropixel avalanche photodiode (MAPD) characterizes its high photon detection efficiency (PDE). It is known that...
We present results of the thermal vacuum testing of Timepix family based detectors with respect to the effects on their properties, sensitivity and behaviour under non-standard conditions. Readout ASIC chip bump-bonded with semiconductor detector was thermally coupled to a small aluminium block. This block was thermally stabilised using a PID controller and a three-stage Peltier element. This...
Hybrid pixel detectors are segmented devices used for particles detection, consisting of a sensor and readout electronics. To improve the resolution of the detector and allow operation with high-intensity photon fluxes, a pixel size is reduced. However, with decreasing pixel size, a charge sharing effect is more significant. To detect a photon irrespectively of charge sharing effect, the total...
We report on the design and measurement results of proton tracking system built with the use of single photon counting hybrid pixel array detector (HPAD). The detector used is Ultra Fast X-Ray Chip (UFXC32k) which is a matrix of 128 x 256 pixels, each 75 um pitch, characterized by very high 50 kfps frame rate. Such features allow it to be used in proton tracking system where high spatial...
We designed a fast neutron activation analysis system with a gamma-ray detector for the detection of explosives. By measuring the prompt gamma-rays emitted from the object upon neutron interrogation, the elements of the material can be identified. This is because the gamma-ray energies emitted by inelastic scattering or capture of fast neutrons present a unique signature for each element of...
In decommissioning, the radiological characterization of potentially contaminated sites is required to estimate the residual activity. Prior to actual samplings for the analysis, scanning survey with a movable radiation detector enables to measure the contaminated sites quickly and find local areas with elevated activity. For the scanning survey, minimum detectable concentration (MDC) of a...
The recent advances in SiPM technology and the high demanding performance required by the current applications, especially in the field of time-of-flight estimation, calls for a new approach in the design of the front-end amplifier to preserve the correct timing of the signals. SiPM manufacturers are offering devices with dedicated pins for fast-time outputs and recommending front-end...
The MASHA setup was developed as a high precision mass-spectrometer for heavy and super heavy elements with masses up to 450 a.m.u. The setup uses ISOL (Isotope Separation On-Line) method. The unique property of MASHA opens also great perspectives for the investigation of neutron rich nuclei produced in multinucleon transfer reactions. Mainly nuclei near the neutron N = 126 and N = 152 shell...
Owing to its high atomic number GaAs is an attractive material to realize hard-X-ray single-photon detectors. In fact, its bandgap of 1.42 eV is on the one hand sufficiently wide to operate it at room temperature and on the other hand small enough to provide reasonable spectroscopic performances for high-energy photons. Therefore, III-V semiconductors avalanche photodiodes have been developed...
The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown after the large tsunami caused by the Great East Japan Earthquake of March 11, 2011. Radiation distribution measurements inside the buildings of the FDNPS are indispensable to execute the decommission tasks because the information would be important to predict risk...
This study presents an effective volume stitching method in dental computed tomography (DCT) using a bone surface-based registration with improved image quality. It consists of four main steps: (1) acquisition of two separate DCT datasets of a small field-of-view (FOV), (2) computation of a three-dimensional transformation for volumetric registration, (3) image registration, and (4) alpha...
Silicon Photomultipliers (SiPMs) [1] are currently an excellent option to replace the traditional photomultiplier tubes (PMTs) in several fields ranging from astrophysics to medical applications. Having photon detection efficiencies (PDE) higher than 40% at peak wavelengths (in the blue-green visible part of the spectra), much lower operational voltages (ranging between 27 and 70 volts,...
Digital tomosynthesis (DTS) is a geometric tomography technique by limited-angle scan that has popularly been used in both medical and industrial x-ray imaging applications. It provides the tomographic benefits of computed tomography (CT) with reduced dose and time. However, conventional DTS reconstruction based on computationally-cheap filtered-backprojection (FBP) method typically produces...
Radioactive contamination of nuclear power plants must be precisely identified for safe decommissioning. Especially, hot spots should be evaluated for the safety of workers in high dose environments. Gamma cameras are widely used to investigate the hot spots of the radioactive materials. The output signals of the gamma cameras are saturated in high dose regions. Pinhole collimator is widely...
Brain-dedicated positron emission tomography (B-PET) aimed at diagnosing Alzheimer disease is being developed. Unlike the existing PET used in combination with MRI or CT, B-PET will be operated independently without additional equipment. Therefore, a study is needed for PET-based correction method, which replaces a CT-based method for quantitative assessment as well as improved quality of an...
