X-ray Detection Methods Research Articles

Research on picosecond synchronization control between synchrotron radiation X-ray pulse and femtosecond laser pulse on SSRF

The laser-pumped X-ray detection method is a crucial tool for investigating molecular dynamics, allowing researchers to study ultrafast structural changes within materials. This method demands extremely high precision in the synchronization and delay timing between the pump pulse and the probe pulse. In this study, we explored picosecond (ps)-level clock synchronization control between synchrotron radiation X-ray pulses and femtosecond (fs) laser pulses at the BL05U (d-Line) of the Shanghai Synchrotron Radiation Facility (SSRF). Utilizing the X-ray pulses generated by the 40 ps/0.3 mA electron beam bunch from the SSRF and femtosecond laser pulses with high repetition rates and high emission power, we conducted synchronization experiments. A custom-developed picosecond time synchronization control system and a high dynamic range X-ray streak camera with picosecond time resolution were used as detectors, enabling ultra-precise time synchronization monitoring of X-ray and laser pulses. This setup achieves higher time resolution without the need for photodiodes and oscilloscopes. Using the X-ray pulses as a stationary reference frame, we adjusted the clock synchronization control system to delay the laser pulses and measured their relative timing changes with the X-ray streak camera. The experiments demonstrated a time resolution better than 10 ps, providing a foundation for achieving 60 ps time resolution in laser-pumped X-ray detection experiments at the SSRF.

Application of Control Algorithm in the Design of Automatic Crimping Device for Connecting Pipe and Ground Wire

Due to the low effectiveness and poor quality of manual crimping of grounding wires, the author proposes the design of an automatic crimping device for connecting tube grounding wires based on intelligent fully automatic technology. The device consists of a microcontroller, an upper computer control interface, an electric push rod, an infrared sensor, a pressure transmitter, and other devices. The staff used the upper computer monitoring interface to set the relevant parameters for grounding wire crimping, and used X-ray digital imaging technology to measure the crimping size of the grounding wire. The size met the set parameter conditions. Through the PID control algorithm in the microcontroller, the stepper motor was controlled to push the clamp to move, completing the automatic crimping of the grounding wire. The X-ray detection method was introduced to detect the quality of the grounding wire after the crimping was completed. The experimental results show that the average deviation between the measured crimping size of the grounding wire and the actual measurement size by the automatic crimping device is only 0.06 mm, indicating that its measurement results are accurate; The success rate of crimping exceeds 95%. The above experimental results verify that the designed crimping device has high stability and reliability, and good quality detection effect.

Design of Monolithic Bi-Layer High-Z PAL-Si Hard X-ray CMOS Image Sensors for Quantum Efficiency Enhancement

This article experimentally investigates the inception of an innovative hard X-ray photon energy attenuation layer (PAL) to advance high-energy X-ray detection (20–50 keV). A bi-layer design with a thin film high-Z PAL on the top and Si image sensor on the bottom has previously demon-strated quantum yield enhancement via computational methods by the principle of photon energy down conversion (PEDC), where high-energy X-ray photon energies are attenuated via inelastic scattering down to ≤10 keV, which is suitable for efficient photoelectric absorption by Si. Quantum yield enhancement has been experimentally confirmed via a preliminary demonstration using PAL-integrated Si-based CMOS image sensors (Si CIS). Furthermore, substituting the high-Z PAL with a lower-Z material—Sn—and alternatively coupling it with a conventional scintillator ma-terial—Lutetium-yttrium oxyorthosilicate (LYSO)—have been compared to demonstrate the most prominent efficacy of monolithic integration of high-Z PAL on Si CIS to detect hard X-rays, paving the way for next-generation high-energy X-ray detection methods.

Novel automated spinal ultrasound segmentation approach for scoliosis visualization.

Scoliosis is a 3D deformity of the spine in which one or more segments of the spine curve laterally, usually with rotation of the vertebral body. Generally, having a Cobb angle (Cobb) greater than 10° can be considered scoliosis. In spine imaging, reliable and accurate identification and segmentation of bony features are crucial for scoliosis assessment, disease diagnosis, and treatment planning. Compared with commonly used X-ray detection methods, ultrasound has received extensive attention from researchers in the past years because of its lack of radiation, high real-time performance, and low price. On the basis of our previous research on spinal ultrasound imaging, this work combines artificial intelligence methods to create a new spine ultrasound image segmentation model called ultrasound global guidance block network (UGBNet), which provides a completely automatic and reliable spine segmentation and scoliosis visualization approach. Our network incorporates a global guidance block module that integrates spatial and channel attention, through which long-range feature dependencies and contextual scale information are learned. We evaluate the performance of the proposed model in semantic segmentation on spinal ultrasound datasets through extensive experiments with several classical learning segmentation methods, such as UNet. Results show that our method performs better than other approaches. Our UGBNet significantly improves segmentation precision, which can reach 74.2% on the evaluation metric of the Dice score.

Towards More Efficient Security Inspection via Deep Learning: A Task-Driven X-ray Image Cropping Scheme.

X-ray imaging machines are widely used in border control checkpoints or public transportation, for luggage scanning and inspection. Recent advances in deep learning enabled automatic object detection of X-ray imaging results to largely reduce labor costs. Compared to tasks on natural images, object detection for X-ray inspection are typically more challenging, due to the varied sizes and aspect ratios of X-ray images, random locations of the small target objects within the redundant background region, etc. In practice, we show that directly applying off-the-shelf deep learning-based detection algorithms for X-ray imagery can be highly time-consuming and ineffective. To this end, we propose a Task-Driven Cropping scheme, dubbed TDC, for improving the deep image detection algorithms towards efficient and effective luggage inspection via X-ray images. Instead of processing the whole X-ray images for object detection, we propose a two-stage strategy, which first adaptively crops X-ray images and only preserves the task-related regions, i.e., the luggage regions for security inspection. A task-specific deep feature extractor is used to rapidly identify the importance of each X-ray image pixel. Only the regions that are useful and related to the detection tasks are kept and passed to the follow-up deep detector. The varied-scale X-ray images are thus reduced to the same size and aspect ratio, which enables a more efficient deep detection pipeline. Besides, to benchmark the effectiveness of X-ray image detection algorithms, we propose a novel dataset for X-ray image detection, dubbed SIXray-D, based on the popular SIXray dataset. In SIXray-D, we provide the complete and more accurate annotations of both object classes and bounding boxes, which enables model training for supervised X-ray detection methods. Our results show that our proposed TDC algorithm can effectively boost popular detection algorithms, by achieving better detection mAPs or reducing the run time.

Dust-enshrouded AGNs Can Dominate Host-galaxy-scale Cold Dust Emission

Abstract It is widely assumed that long-wavelength infrared (IR) emission from cold dust (T ∼ 20–40 K) is a reliable tracer of star formation even in the presence of a bright active galactic nucleus (AGN). Based on radiative transfer (RT) models of clumpy AGN tori, hot dust emission from the torus contributes negligibly to the galaxy spectral energy distribution (SED) at λ ≳ 100 μm. However, these models do not include AGN heating of host-galaxy-scale diffuse dust, which may have far-IR (FIR) colors comparable to cold diffuse dust heated by stars. To quantify the contribution of AGN heating to host-galaxy-scale cold dust emission at λ ≳ 100 μm, we perform dust RT calculations on a simulated galaxy merger both including and excluding the bright AGN that it hosts. By differencing the SEDs yielded by RT calculations with and without AGNs that are otherwise identical, we quantify the FIR cold dust emission arising solely from reprocessed AGN photons. In extreme cases, AGN-heated host-galaxy-scale dust can increase galaxy-integrated FIR flux densities by factors of 2–4; star formation rates calculated from the FIR luminosity assuming no AGN contribution can overestimate the true value by comparable factors. Because the FIR colors of such systems are similar to those of purely star-forming galaxies and redder than torus models, broadband SED decomposition may be insufficient for disentangling the contributions of stars and heavily dust-enshrouded AGNs in the most IR-luminous galaxies. We demonstrate how kiloparsec-scale resolved observations can be used to identify deeply dust-enshrouded AGNs with cool FIR colors when spectroscopic and/or X-ray detection methods are unavailable.

STUDY ON ROTATIONAL VISCOSITY OF NEMATIC LYOTROPIC LIQUID CRYSTAL

Lyotropic liquid crystal exhibits excellent biocompatibility, non-toxicity, biodegradability, optical anisotropy, and electromagnetic anisotropy. It has been widely used in the areas of biology, medical engineering and liquid crystal displaying, such as cell interaction, nerve stimulation transmission, fat absorption and intelligent drug transport. In this paper, the rotational viscosity of the lyotropic liquid crystal Sunset Yellow in the nematic phase at different temperature and solution concentration is measured by the rotating magnetic field method. Combined with the self-assembly process of lyotropic liquid crystal molecules, the variation of rotational viscosity of lyotropic liquid crystal in the nematic phase with temperature and solution concentration is analyzed theoretically. The results show that the rotational viscosity of the lyotropic liquid crystal is positively correlated with the square of the average length of the self-assembled columns, increasing with the increase of concentration, but decreasing exponentially with the increase of temperature. The empirical expression of rotational viscosity related to temperature and concentration of nematic lyotropic liquid crystal is constructed. The calculated results of the empirical expression are in good agreement with the experimental values, with the maximum error of 18.56${\%}$. A new indirect of obtaining the shear energy of lyotropic liquid crystal by using rotating rheometer is proposed. The shear energy of lyotropic liquid crystal increases with the increase of solution concentration, but it is hardly related with the change of temperature in the experimental range. The shear energy obtained in this paper is in good agreement with the results of Joshi et al. who used the X-ray detection method, with the maximum error of 3${\%}$. The influence of length-diameter ratio of the columns on the rotational viscosity is investigated by using the variation of self-assembly capacity of liquid crystal molecules with temperature. The one-step method measurement is proposed, which greatly reduces the expenses and complexity of related experimental researches.

The method of pulsed x-ray detection with a diode laser

A new class of pulsed X-ray detection methods by sensing carrier changes in a diode laser cavity has been presented and demonstrated. The proof-of-principle experiments on detecting pulsed X-ray temporal profile have been done through the diode laser with a multiple quantum well active layer. The result shows that our method can achieve the aim of detecting the temporal profile of a pulsed X-ray source. We predict that there is a minimum value for the pre-bias current of the diode laser by analyzing the carrier rate equation, which exists near the threshold current of the diode laser chip in experiments. This behaviour generally agrees with the characterizations of theoretical analysis. The relative sensitivity is estimated at about 3.3 × 10-17 C ⋅ cm2. We have analyzed the time scale of about 10 ps response with both rate equation and Monte Carlo methods.

A weight-of-evidence approach to identify nanomaterials in consumer products: a case study of nanoparticles in commercial sunscreens.

Nanoscale ingredients in commercial products represent a point of emerging environmental concern due to recent findings that correlate toxicity with small particle size. A weight-of-evidence (WOE) approach based upon multiple lines of evidence (LOE) is developed here to assess nanomaterials as they exist in consumer product formulations, providing a qualitative assessment regarding the presence of nanomaterials, along with a baseline estimate of nanoparticle concentration if nanomaterials do exist. Electron microscopy, analytical separations, and X-ray detection methods were used to identify and characterize nanomaterials in sunscreen formulations. The WOE/LOE approach as applied to four commercial sunscreen products indicated that all four contained at least 10% dispersed primary particles having at least one dimension <100 nm in size. Analytical analyses confirmed that these constituents were comprised of zinc oxide (ZnO) or titanium dioxide (TiO2). The screening approaches developed herein offer a streamlined, facile means to identify potentially hazardous nanomaterial constituents with minimal abrasive processing of the raw material.

Picosecond resolving detection method and experiment for ultrafast X-ray by modulation of an optical probe

Diagnostic measurement of single picosecond event in high energy density physics, laser fusion, plasma radiation, and combustion, is of great importance. However, the measuring of the shape of the single X-ray pulse and the synchronization of X-ray and the laser pulse in picosecond resolution is still a great challenge. Restricted by the transit time of electrons, the time-resolution limit of a conventional framing camera based on the microchannel plate is 40 ps. Centered on the full-optical modulation effect of the light-probe, a novel method for X-ray detection of picoseconds temporal resolution based on low temperature GaAs is proposed in this work. The basic physical mechanism of the detector can be explained in both macroscopical and microcosmic ways. In the macroscopical way, the X-ray radiation absorption in the sensor material produces a transient, non-equilibrium electron-hole pair distribution that results in a transient differential change of the local refractive index, which is then sensed by the reflectivity changes of the optical probe beam. In the microcosmic way, X-ray absorption creates photoelectrons and the core level holes are subsequently filled through Auger or fluorescence processes. These excitations ultimately increase conduction and valence band carriers that perturb optical reflectivity.#br#To verify the proposed X-ray detection method, a Fabry-Perot detector is designed, which consists of a 5 μm thick GaAs layer surrounded by a GaAs/AlAs distributed Bragg reflector. The test is carried out on a femtosecond laser facility, where the X-ray source is produced by focusing the 56 fs Ti: Sapphire facility laser, with a central wavelength of 800 nm, onto an aluminum foil. Then the X-ray pulse induces a transient optical reflectivity change in GaAs, which is a powerful tool for establishing the high-speed X-ray detection.#br#The experimental results indicate that this technology can be used to provide X-ray detectors with a temporal resolution of tens of picoseconds. By optimizing the material, the temporal resolution can be enhanced to be less than 1 ps. Through further development, this X-ray detector could provide an insight into previously unmeasurable phenomena in many fields. Future work will focus on developing much faster devices characterizing both the rise and fall time and imaging array technology.

Ulrich Wolfgang Arndt. 23 April 1924 — 24 March 2006

Ulrich (Uli) Arndt was a physicist and engineer whose contributions to the development of a wide range of instrumentation for X-ray crystallography played an important part in our ability to solve the atomic structure of large biological molecules. Such detailed information about protein structures has for the past 50 years underpinned the huge advances in the field of molecular biology. His innovations spanned all aspects of data generation and collection, from improvements in X-ray tubes, through novel designs for diffractometers and cameras to film scanners and more direct methods of X-ray detection. When he started in the field, the intensities of individual X-ray reflections were often estimated by eye from films. By the end of his career the whole process of collecting from a crystal a three-dimensional data set, possibly comprising hundreds of thousands of measurements, was fully automated and very rapid.

ELEMENT 115 X-ray evidence supports the existence of the superheavy element

Confirmatory evidence for the existence of element 115 has been reported by an international research team that successfully used X-ray detection methods for the first time. The new work should bolster the case for adding the element to the periodic table almost a decade after it was first spotted. Nuclear physicist Dirk Rudolph of Lund University, in Sweden, led the team. The scientists did the experiment at the GSI heavy ion accelerator center in Darmstadt, Germany. A paper of the work has been accepted by Physical Review Letters. Element 115 was first observed by physicists at Russia’s Joint Institute for Nuclear Research working with scientists from Lawrence Livermore National Laboratory. An international committee of chemists and physicists will decide whether to add the element to the periodic table. Rudolph’s team created element 115 by aiming a beam of calcium ions at an americium target. Sifting through the jumble of photons, ...

A photoinduced discharge X-ray detector using photoconductors: influence of the material selection on the electronic properties.

In the Photo-Induced Discharge (PID) method of X-ray detection, image information generated by X-rays is derived using a readout laser. The structure of the PID detector consists of multiple layers with different functionalities. A high voltage is applied between the top and bottom layers, generating an electric field for separating the electron-hole pairs (EHPs) generated by X-rays in a photoconductor layer. A separate dielectric layer is used to trap EHPs. Improvements to detection efficiency are accomplished by selecting new photoconductor materials as a substitute for amorphous selenium (a-Se), commonly used in existing PID methods. The photoconductor material also determines the optimal wavelength of an appropriate readout laser. Lead oxide, lead iodide, mercury iodide, and mercury iodide (with additives) were tested as alternative photoconductor materials with low dark current. The readout laser used here operates at wavelengths of 459 nm and 620 nm. The reaction characteristic on the readout laser was measured in all four types of photoconductors. Detection properties were compared to a flat panel detector. No reaction characteristics could be measured for lead oxide and lead iodide for either wavelength. The mercury iodide photoconductor (including additives) reacted to the 495 nm wavelength, but showed a weak, inconsistent signal for different measurements. The mercury iodide photoconductor showed excellent characteristics for both wavelengths, but was superior for a wavelength of 495 nm. The mercury iodide-based PID sensitivity was measured at 0.4 nc/mR cm2 with a dark current at 0.5 nA/cm2 and signal to noise ratio (SNR) of 340. These results show a lower sensitivity compared to existing flat panel detectors, but show a much lower dark current. Consequently, SNR values approximately 260 times higher were observed in the PID detector as compared with a flat panel detector.

X-Ray Image Detector Based on Light Guides and Scintillators

This paper reports on a study concerning the design of an X-ray detector that is suitable to analyze a small area with high spatial resolution. The indirect method of X-ray detection is used, i.e., the X-rays are first converted into visible light, which is then detected. In this design, an array of CsI:Tl scintillators, encapsulated by aluminum walls, is coupled with an array of CMOS photodetectors. This structure, patented and described theoretically by the authors in previous works, can be obtained using the SU-8 negative photoresist as a sacrificial layer. The experimental work consisted in the deposition of a scintillator layer, and an aluminum layer on the active area of a commercially available digital imaging sensor, thus supporting the developed detector design. X-ray imaging tests were performed using the PHILIPS X'Pert equipment. Promising results were obtained, featuring high resolution and detail.

High Tc SQUID System for Detection of Small Metallic Contaminant in Industrial Products

A three channel High-Tc SQUID system for detection of magnetic contaminants in industrial products was developed. Finding ultra-small metallic contaminants is a big issue for manufacturers producing commercial products such as lithium ion batteries. When the contamination does occur, the manufacturer of the product suffers a great loss to recall the tainted products. The outer dimension of metallic particles less than 100 micron can not be detected by X-ray imaging, which is commonly used as the inspection method. Therefore, a highly sensitive detection system for small contaminants is required. We developed a detection system based on a three channel high-Tc SQUID microscope with a high performance magnetic shield. Three SQUIDs were installed in one microscope-type cryostat with a 3" sapphire vacuum window which separates the SQUID and atmosphere. This design enables the SQUID to approach an object to be measured as close as 1 mm. The minimal detectable size of the particle is also highly dependent on the magnetic field noise of the SQUID. Therefore, we employed double transformer coupling, which lowers the noise. One transformer was placed at 77 K and the other was at room temperature (RT). As a result, the magnetic field noise of the SQUID was reduced by 36%. Finally we could successfully measure small iron particles as small as 30 micron. This detection level was difficult to achieve when using a conventional X-ray detection method.

METALLIC CONTAMINANT DETECTION SYSTEM FOR INDUSTRIAL PRODUCTS BY HIGH TC SQUID MAGNETIC SENSOR

High-Tc superconducting quantum interference device (SQUID) system for detection of magnetic foreign matter in industrial products was developed. There is a possibility that ultra-small metallic foreign matter has been accidentally mixed with industrial products, such as lithium ion batteries. The outer dimension of metallic particles less than 100 microns cannot be detected by conventional X-ray imaging. Therefore, we developed a detection system based on high-Tc SQUID microscopes with a high-performance magnetic shield. Using SQUID microscopes with a 0.5 mm-thick vacuum window was proposed. This design enables the SQUID to approach an object to be measured as close as 1 mm and enhances the sensitivity. A new magnetic shield with sleeves was carefully designed and built. As a result, we could successfully measure a small iron particle with 100 μm. This detection level was hard to achieve by conventional X-ray detection methods.

A high-Tc SQUID micro-detector with a high performance magnetic shield for contaminant detectionin industrial products

A high-Tc superconducting quantum interference device (SQUID) system for the detection ofmagnetic foreign matter in industrial products was developed. There is a possibility thatultra-small metallic foreign matter has been accidentally mixed with industrial productssuch as lithium ion batteries. Metallic particles with outer dimensions less than100 µm cannot be detected by conventional x-ray imaging. Therefore we developed a detection system based ona high-Tc SQUID microscope with a high performance magnetic shield. The use of SQUIDmicroscopes with a 0.5 mm thick vacuum window was proposed. This design enables theSQUID to approach the object to be measured as close as 1 mm and enhancesthe sensitivity. A new magnetic shield with sleeves was carefully designedand built. As a result, we could successfully measure small particles sized100 µm. This detection level was hard to achieve using a conventional x-ray detection method.

Development of a lens-coupled CMOS detector for an X-ray inspection system

A digital X-ray imaging detector based on a complementary metal-oxide-semiconductor (CMOS) image sensor has been developed for X-ray non-destructive inspection applications. This is a cost-effective solution because of the availability of cheap commercial standard CMOS image sensors. The detector configuration adopts an indirect X-ray detection method by using scintillation material and lens assembly. As a feasibility test of the developed lens-coupled CMOS detector as an X-ray inspection system, we have acquired X-ray projection images under a variety of imaging conditions. The results show that the projected image is reasonably acceptable in typical non-destructive testing (NDT). However, the developed detector may not be appropriate for laminography due to a low light-collection efficiency of lens assembly. In this paper, construction of the lens-coupled CMOS detector and its specifications are described, and the experimental results are presented. Using the analysis of quantum accounting diagram, inefficiency of the lens-coupling method is discussed.

The PX-AMS system and its applications at CIAE

The projectile X-ray detection method (PXD) has been set up in the China Institute of Atomic Energy AMS system. Using this method, the half-life of 79Se and 75Se have been measured, the intensity of 64Cu radioactive nuclear beams have been identified, and the upper limit of transition probability of the first excited state of 64Cu was obtained.

The PX-AMS system and its applications at CIAE

The projectile X-ray detection method (PXD) has been set up in the China Institute of Atomic Energy AMS system. Using this method, the half-life of 79 Se and 75 Se have been measured, the intensity of 64 Cu radioactive nuclear beams have been identified, and the upper limit of transition probability of the first excited state of 64 Cu was obtained.