Delta Rays Research Articles

Cherenkov real-time monitor for proton flash therapy

Flash therapy with ultra-high dose rate beams opens up the possibility of significantly reducing radiation damage to normal tissues. But that type of radiotherapy requires the development of new methods for dosimetry and monitoring of beams, since many conventional detectors are not fully suitable for these purposes. In this work, the characteristics of a new proton beam monitor that detects Cherenkov radiation from secondary delta electrons were studied in flash mode of irradiation. This monitor is applicable for proton beams of any intensity, very transparent for fast protons, and can provide real-time control of the absorbed dose and beam position. To record Cherenkov radiation, generated in a thin glass radiator located in the beam in front of the target, we used single-channel and multichannel photomultipliers. Proton beams with an energy of 160 MeV and a current of 1 mA were studied. The readings of a Cherenkov monitor, EBT-XD films, and a beam current transformer were compared and consistency of these detectors was found. The linearity of the Cherenkov monitor readings vs dose is very high (R 2 = 0.9995). This monitor can be used for real-time control of the absorbed dose and of the beam position in flash therapy for any intensity of proton beams.

EXPERIMENTAL DATA GENERALIZATION OF DELTA ELECTRON YIELD INDUCED BY HIGH ENERGY ELECTRON INTERACTION WITH AMORPHOUS AND SINGLE-CRYSTAL TARGETS

The generalized experimental results of delta electron yield obtained at the NSC KIPT electron accelerators in the energy range from 0.5 MeV to 1.6 GeV are presented. Thin foils of Be, Al, Si, Ni, and Nb were used as experimental targets. It was established in general that delta electron yield is roportional to the product √T∙Z/A, where T is the thickness of the sample in g/cm2 and it has a linear dependence. It is shown that the main factor of delta elec- tron yield increasing is not primary beam energy, but the electron density of the experimental target

Effect of hydrogen on oxidative dissolution of epsilon particles-doped UO2 pellets under carbonate condition with hydrogen peroxide

The epsilon particles that result from nuclear fission of UO2 fuel possess both advantages and disadvantages from a spent nuclear fuel (SNF) management perspective. In this study, the effect of epsilon particles, namely Ru, Mo, and Pd, inherent in simulated UO2 pellets is examined. Various analytical methods have been used to explore the changes in the structural, surface, and electrochemical properties of which contain epsilon particles. A notable finding is that the epsilon particles are not evenly distributed and tend to clump together, transforming into a metallic state after sintering, as detailed in the X-ray diffraction analyses. Energy-dispersive X-ray spectroscopy analyses highlight interesting aspects of the distribution of elements, especially the disappearance of Pd during sintering, which is likely due to its high vapor pressure. Although the lattice structure of UO2 remains unchanged, the sizes of the grains and pores visibly change, which may influence the tendency of UO2 pellet-cracking. Despite the addition of the epsilon particles, the electrical conductivity analyses show no significant changes, suggesting that they act as minor impurities without affecting the structural lattice. However, their possible role as catalysts in electrochemical reactions opens new and interesting areas that require thorough investigation. Moreover, examining the anodic dissolution under various conditions provides detailed insights into UO2 dissolution and oxidation, revealing how epsilon particles subtly influence the oxidative dissolution process. This study clarifies the basic interactions and effects of epsilon particles in UO2 pellets and broadens the path for a deeper understanding and improvement of nuclear fuel matrices and steering advancements in the safe and effective use of nuclear energy.

Application of deep learning and statistical methods in predicting Taiwanese stock trends

Since its inception, the stock market has been a topic of considerable interest. Its variation and the complexity of integrating technology into the stock market have made it difficult for stock market trends to be fully understood. Various metrics and analytical approaches have been proposed in response to such changes, ranging from purely technical metrics to hardware upgrades. The widespread application of deep learning in the stock market, from basic metrics (opening price, closing price, highest price, lowest price, trading volume) to machine learning in sentiment analysis, further increases the possibility of increasing profits. Some front-end techniques, such as noise reduction through mathematical models, enhance the accuracy of deep learning models. However, few studies have centered on predicting long-term stock price changes. The traditional moving average (MA) cannot rapidly reflect drastic changes on its curve even though it can display trends; therefore, this study proposes an MA-based approach that improves the 200-day MA such that its delayed response to actual prices in real-time can be overcome. This deep learning model training was performed by combining 200-day MA data with two other types of MA data, thereby creating a new approach to metric analysis. The sample consisted of stocks of 13 Taiwanese companies with a high market cap: Taiwan Semiconductor Manufacturing Co., Ltd., MediaTek Inc., Chunghwa Telecom Co., Ltd., Fubon Financial Holding Co., Ltd., Cathay Financial Holding Co., Ltd., Nan Ya Plastics Corp., United Microelectronics Corp., Delta Electronics, Inc., CTBC Financial Holding Co., Ltd., Mega Financial Holding Co., Ltd., Formosa Chemicals & Fibre Corp., Hon Hai Precision Industry Co., Ltd., and Formosa Plastics Corp. Through multiple evaluation metrics, the experimental results revealed that the proposed model performed better in general than the traditional MA model for all stocks.

Nanocomposite physics and structure considerations in MCNP proton shielding models

Background Deep space crewed missions require unique radiation shielding considerations. Due to mission duration and the heavy, high-energy nature of deep space radiation, the aluminum alloys that have historically been used for spacecrafts do not provide sufficient protection for crew members. Polymer-based nanocomposites have been proposed as potential radiation shielding materials for deep space applications; however, the high tunability of nanocomposites and the limited number of facilities able to produce representative radiation energies presents barriers to nanocomposite testing. Computational approaches may allow for preliminary investigation and discrimination of nanocomposite parameters like polymer and filler composition, loading percentage, and filler size and structure. Methods This work aims to investigate several modeling methods to perform radiation transport simulations for a nanocomposite, particularly with regards to modeling the filler nanostructure and the involved physics. Published experiments of a polydimethylsiloxane-carbon nanotube nanocomposite in 63 MeV and 105 MeV proton beams were digitally recreated in MCNP6.2 with three different nanocomposite structures. Additionally, several simulations were performed under various physics assumptions. The computationally determined water equivalent thicknesses are compared between modeling methods, as well as between the computational and the published experimental work. Results Nanostructure model complexity had no impact on the computed water equivalent thickness, with <1% difference between the three modeling methods. The inclusion of delta ray production and tracking physics produced a slight decrease in the computed water equivalent thickness and significantly increased the computational time for a single simulation by a factor of 35.7. Computationally determined water equivalent thicknesses are within 5% of published experimentally determined values. Conclusions Shielding capabilities of a polymer/carbon nanotube nanocomposite estimated using Monte Carlo radiation transport models agree well with published experimental results, even with a simplistic representation of the nanocomposite material. Radiation transport settings influenced the resulting water equivalent thickness as well as computational resource needs.

The elimination of an artifact in the FLURZnrc-derived electron-fluence spectrum close to the Spencer-Attix-Nahum cut-off Δ

Objective. An artifact in the electron fluence, differential in energy, Φ E , computed by the EGSnrc Monte-Carlo user-code FLURZnrc, was identified and a methodology has been developed to eliminate it. This artifact manifests itself as an ‘unphysical’ increase in Φ E at energies close to the production threshold for knock-on electrons, AE; this in turn causes an over-estimation of the Spencer-Attix-Nahum (SAN) ‘track-end’ dose by a factor ∼1.5, thereby inflating the dose derived from the SAN cavity integral. For SAN cut-off Δ SAN = 1 keV for 1 MeV and 10 MeV photons in water, aluminium and copper, with maximum fractional energy loss per step ESTEPE = 0.25 (default value), this anomalous increase in the SAN cavity-integral dose is of the order of 0.5%–0.7%. Approach. The dependence of Φ E on the value of AE (the maximum energy loss involved in the restricted electronic stopping power (dE/ds) AE ) at or close to Δ SAN was investigated; this was done for different values of ESTEPE. Main results. The error in the electron-fluence spectrum occurs when Δ SAN is set close to or equal to AE; this error disappears (at the 0.1% level or better) if AE is set ≤ 0.5 × Δ SAN. However, if ESTEPE ≤ 0.04 the error in the electron-fluence spectrum is negligible even when Δ SAN = AE. Significance. An artifact in the FLURZnrc-derived electron fluence, differential in energy, at or close to electron energy AE has been identified. It is shown how this artifact can be avoided, thereby ensuring the accurate evaluation of the SAN cavity integral.

The Impact of Covid-19 on International Trade in China- Industry Review in the YRD and the PRD

Since the Covid-19 pandemic raged on a global scale, the trade of various countries has been affected to varying degrees. China faces significant challenges as one of the top countries in international trade. Although the epidemic situation in most countries around the world has improved significantly and trade levels are gradually resuming, China's trade is still affected by the domestic ‘Dynamic Covid-Zero’ policy and cannot return to pre-epidemic levels. The Yangtze River Delta and the Pearl River Delta are the most representative economic zones in China, their import and export trade are greatly influenced. The authors examine various facts and information in order to solve concerns produced by Covid-19 and Chinese policy in a variety of industries in international trade, and they also give some solutions. In this paper, the authors focus on (1) the overall current state of international trade in China; (2) Chinese policy of the government responses to the Covid-19 (3) the current state of the textile industry in the Yangtze River Delta, data analysis, and internal and external challenges; (4) the current situation of the Pearl River Delta's electronics manufacturing business, data analysis, and internal and external challenges; and (5) possible solutions from the government perspective.

Nanoscale mapping of point defect concentrations with 4D-STEM

Vacancies are missing atoms in a crystalline material, and occur both at equilibrium (varying with temperature) and out of equilibrium such as when crystalline materials are damaged with radiation or corrosion. While we know of their importance, particularly regarding diffusive mechanisms, it is not straightforward to experimentally measure their concentration or to visualize them directly. Traditionally, measurements such as positron annihilation spectroscopy and to some degree X-ray diffraction can measure average concentrations, but generally lack the ability to visualize or quantify a heterogenous concentration of vacancies that can occur at the level of individual defects and microstructural features. Here, we present a method to map vacancy concentrations and their distribution using local lattice parameter measurements with a high-resolution electron microscope. Our method utilizes a Au thin film as a model to demonstrate the method via four-dimensional scanning transmission electron microscopy (4D-STEM) by correlating the differences between changes in lattice parameter and the volumetric thermal expansion during in situ heating experiments. The vacancy mapping methodology is also applied to non-equilibrium defects accumulated in pure Al via knock-on electron beam irradiation. Our method demonstrates the ability to map point defect concentrations in heterogeneous systems in situ with nanometer spatial resolution. The result is a technique that can provide direct measurements of vacancy concentrations at the level of individual defects in studies of materials in and out of equilibrium.

Energy-Loss Straggling and Delta-Ray Escape in Solid-State Microdosimeters Used in Ion-Beam Therapy

Microdosimetry is increasingly adopted in the characterization of proton and carbon ion beams used in cancer therapy. Spectra and mean values of lineal energy calculated in frequency and dose are seen by many as the tools which, by complementing dosimetric measurements, allow for the most complete characterization of the therapeutic radiation fields. The urgency is now to consolidate the experience and converge to commonly accepted methodologies. In this context, the purpose of this work is to study the effects of the energy-loss straggling and the delta-ray escape, considering slab-sensitive volumes; these are, in fact, the typical shapes of solid-state microdosimeters, which are widely used in investigating light ion therapy beams. The method considers the energy distribution of delta rays resulting from the collision of the impinging ion and, taking into account the escape, convolutes it with itself as many times as the expected number of collisions in the sensitive volume thickness. The resulting distribution is compared to the experimental microdosimetric spectrum showing a substantially good agreement. The extension of the methodology to a wider range of ion energy and detector characteristics is instrumental for a detector-independent microdosimetric assessment of the radiation fields.

Energy Deposition by Ultrahigh Energy Ions in Large and Small Sensitive Volumes

The deposition of energy in large and small sensitive volumes is studied after ultrahigh energy heavy-ion irradiation. We demonstrate that the energy deposition increase effect previously reported in p-i-n diode detectors due to delta electrons occurs only in large sensitive volumes, but not in small ones, typical of advanced microelectronic devices, such as the cells of a 3-D NAND Flash memories. We attribute this effect to the trajectories of the secondary electrons.

Intelligent Fault Detection, Diagnosis and Health Evaluation for Industrial Robots

The focus of this study is development of an intelligent fault detection, diagnosis and health evaluation system for real industrial robots. The system uses principal component analysis based statistical process control with Nelson rules for online fault detection. Several suitable Nelson rules are chosen for sensitive detection. When a variation is detected, the system performs a diagnostic operation to acquire features of the time domain and the frequency domain from the motor encoder, motor current sensor and external accelerometer for fault diagnosis with a multi-class support vector machine. Additionally, a fuzzy logic based robot health index generator is proposed for evaluating the health of the robot, and the generator is an original design to reflect the health status of the robot. Finally, several real aging-related faults are implemented on a six-axis industrial robot, DRV90L7A6213N by Delta Electronics, and the proposed system is validated effectively by the experimental results.

Recommendations and Protocols for the Use of the Isotope Ratio Infrared Spectrometer (Delta Ray) to Measure Stable Isotopes from CO2: An Application to Volcanic Emissions at Mount Etna and Stromboli (Sicily, Italy)

Among major volatiles released from the Earth’s interior, CO2 is an important target for the international community. The interest is keenly motivated by the contribution of CO2 in the Earth’s carbon budget and its role on past, current, and future climate dynamics. In particular, the isotopic signature of CO2 is fundamental to characterize the source of this gas and its evolution up to the atmosphere. The recent development of new laser-based techniques has marked an important milestone for the scientific community by favoring both high-frequency and in situ stable isotope measurements. Among them, the Delta Ray IRIS (Thermo Scientific Inc., Waltham, USA) is one of the most promising instruments thanks to its high precision, its limited interferences with other gaseous species (such as H2S and/or SO2), and its internal calibration procedure. These characteristics and the relative easiness to transport the Delta Ray IRIS have encouraged its use on the field to analyze volcanic CO2 emissions in recent years but often with distinct customized protocols of measurements. In this study, various tests in the laboratory and on the field have been performed to study the dependence of CO2 isotope measurements on analytical, instrumental, and environmental conditions. We emphasize the exceptional ability of the Delta Ray IRIS to perform isotope measurements for a large range of CO2 concentration (200 ppm–100%) thanks to a dilution system and to get a reliable estimation of the real CO2 content from the diluted one. These tests lead to point out major recommendations on the use of Delta Ray IRIS and allow the development of adapted protocols to analyze CO2 emissions like in volcanic environments.

Radiation damage from energetic particles at GRad-level of SiO[formula omitted] fibers of the Large Hadron Collider ATLAS Zero-Degree Calorimeter (ZDC)

Core SiO2 quartz fibers of the Large Hadron Collider (LHC) ATLAS Zero-degree Calorimeter (ZDC) are expected to experience integrated doses of a few giga-Rad (Grad) at their closest position to the LHC beam. An array of fibers was irradiated with 200 MeV protons and spallation-generated mixed spectra (primarily fast neutrons) at the Brookhaven National Laboratory (BNL) Linac. Specifically, 1 mm- and 2 mm-diameter quartz (GE 124) rods of 50 mm length were exposed to direct 200 MeV protons leading to peak integrated dose of ∼28 Grad (∼0.28 GGy). Exposure of 1 mm-diameter SiO2 fibers to a neutron flux was also achieved in the spallation field generated by 128 MeV protons. In the post-irradiation analysis, the quartz fiber transmittance was evaluated as a function of the absorbed dose. Significant degradation of the transmittance and increased radiation damage of the material were observed. Microscopic evaluation of the fibers revealed extensive micro-structural damage and irradiation-induced defects. The measurements revealed that a threshold fluence (∼2.6 1016 p/cm2) or dose of ∼10 Grad (0.1 GGy) appears to exist beyond which light transmittance drops below 10%. Also observed is that fiber transmittance loss increased drastically with SiO2 fiber diameter (1 mm vs. 2 mm diameter). This is attributed, in part, to the earlier lateral leakage from the 1 mm fiber of knock-on electrons and primary protons implying that more damage-inducing protons travel within the bulk of the 50 mm long 2-mm fibers. While Monte Carlo simulations performed tend to support such assumption, future experiments and sensitivity studies are envisioned to address the fiber diameter influence on degradation.

Low-Energy Protons—Where and Why “Rare Events” Matter

Failures (or upsets) of complementary metal-oxide-semiconductor (CMOS) devices, due to direct ionization from protons, were first predicted in 1982 and subsequently realized in 2007 for low-energy (1 MeV) protons (LEPs). For terrestrial applications, secondary LEPs, generated during collision events, may cause upsets, especially in cells far away from the initial strike location than their heavier spallation-fragment cousins. However, direct ionization may be more important in space and high-altitude environments due to the large flux of primary high-energy protons impinging on nearby spacecraft (and local device) shielding. In this article, a brief review of the relevant literature will be followed by a discussion of the sensitivity to direct ionization of typical CMOS devices. It will be shown that a significant number of LEPs are generated by cosmic radiation spallation events, suggesting that track structures and exact device hit locations need to be understood and effectively modeled, especially for modern devices. Also, the rate of multiple cell upsets, and hence multiple bit upsets, in these environments will be explored, with possible mitigation techniques discussed. The published work on muons and delta electrons, in addition to LEPs, will be reviewed as potential single-event upset (SEU) sources with the future scaling of CMOS devices.

A simple model for calculating relative biological effectiveness of X-rays and gamma radiation in cell survival.

The relative biological effectiveness (RBE) of X-rays and γ radiation increases substantially with decreasing beam energy. This trend affects the efficacy of medical applications of this type of radiation. This study was designed to develop a model based on a survey of experimental data that can reliably predict this trend. In our model, parameters α and β of a cell survival curve are simple functions of the frequency-average linear energy transfer (LF) of delta electrons. The choice of these functions was guided by a microdosimetry-based model. We calculated LF by using an innovative algorithm in which LF is associated with only those electrons that reach a sensitive-to-radiation volume (SV) within the cell. We determined model parameters by fitting the model to 139 measured (α,β) pairs. We tested nine versions of the model. The best agreement was achieved with [Formula: see text] and β being linear functions of [Formula: see text] .The estimated SV diameter was 0.1-1 µm. We also found that α, β, and the α/β ratio increased with increasing [Formula: see text] . By combining an innovative method for calculating [Formula: see text] with a microdosimetric model, we developed a model that is consistent with extensive experimental data involving photon energies from 0.27 keV to 1.25 MeV. We have developed a photon RBE model applicable to an energy range from ultra-soft X-rays to megaelectron volt γ radiation, including high-dose levels where the RBE cannot be calculated as the ratio of α values. In this model, the ionization density represented by [Formula: see text] determines the RBE for a given photon spectrum.

Optical range determination of clinical proton beams in water. A comparison with standard measurement methods

As recently discovered, water emits a weak luminescence when it is irradiated with protons even with energies below the Cerenkov light threshold. In this work it was investigated if this phenomenon could be exploited for range measurements in proton therapy. A measurement setup based on a scientific CMOS camera that can be operated under normal room light was built and tested in a proof-of-principle experiment at the West German Proton Therapy Center, Essen. The luminescence depth profiles were analyzed to obtain the range information and the method was compared with ionization chamber based depth dose measurements. The noise caused by scattered radiation hitting the camera chip could be removed with a simple threshold-based median filter. The influence of Cerenkov radiation produced by delta electrons was analyzed by FLUKA simulations and it was shown that it does not affect the range measurements. It could be shown that the luminescence method is as fast as the multi-layer ionization chamber measurement (a few seconds) but with a higher depth resolution that is comparable with the Bragg peak chamber method. The proton ranges determined with the luminescence method agree with the reference methods better than 0.2% over the whole energy range 100–226MeV. The sensitivity of the method regarding detectable range shifts was tested. It was shown, that energy shifts of 0.5MeV (at 151MeV), leading to a range shift of ∼0.9mm, were clearly detectable.

K-SHELL IONIZATION AND X-RAY PRODUCTION CROSS SECTIONS BY PROTONS IN VACUUM AND GASEOUS ENVIRONMENT

The Κα ionization and x-ray production cross sections from the bombardment of three metal targets with protons were measured in vacuum and in gaseous environment (external beam technique). Proton energies between 1.5 and 8 MeV were used. The experimental Κ shell ionization and x-ray production cross sections were calculated for the same targets and com­ pared with three theoretical and two semiempirical approxima­ tions. For the measurements in gaseous environment the influ­ence of the secondary electrons (delta electrons) emitted from the gas, to the x-ray yields was investigated. For this pur­ pose a suitable model was introduced and tested experimen­tally.

The impact of sensitive volume thickness for silicon on insulator microdosimeters in hadron therapy

Compact silicon on insulator (SOI) microdosimeters have been used to characterise the radiation field of many different hadron therapy beams. SOI devices are particularly attractive in hadron therapy fields due to their spatial resolution being well suited to the sharp dose gradients at the end of the primary beam’s range. Due to the small size of SOI’s sensitive volumes (SVs), which are usually ∼1–10 m thick, the fabrication of these devices can present challenges which are not as common for more conventional thickness silicon devices such as silicon spectroscopy detectors. Microdosimetry is the study of the energy deposition in micrometre sized volumes representing biological sites and is a powerful approach to estimate the biological effect of radiation on the micron-scale level, in a cell. However, cell sizes vary extensively translating in different energy deposition spectra. This work studies SV thicknesses between 1 and 100 m using Geant4 and examines the impact of SV dimensions on microdosimetric quantities. The quantities studied were the frequency mean lineal energy, , and the dose mean lineal energy, . Additionally the relative biological effectiveness (RBE), estimated by the microdosimetric kinetic model (MKM), is also investigated. To study the impact of the SV thickness, SOI microdosimeters were irradiated with proton, and ion beams with ranges of ∼160 mm, with the microdosimeter being set at various positions along the Bragg curve. It was found that was influenced the least in proton beams and increased for heavier ion beams. Conversely, was impacted by the SV thickness the most in proton beams and was the least. Similar to , protons were impacted the most by the SV thickness when estimating the RBE using the MKM. The cause of these differences was largely due to the different densities of the delta electron track structure for the case of and the energy transferred to the medium from the primary beam for .

The ‘teaching away’ description of the prior art and non-obviousness of the invention

Delta Electronics v. Sunonwealth; with Case note by Tien-hsin Wang

Proceedings to the 6th Annual Conference of the Particle Therapy Cooperative Group North America (PTCOG-NA): 14-16 October 2019, Hosted by Miami Cancer Institute, part of Baptist Health South Florida, Miami, FL, USA.

Proceedings to the 6th Annual Conference of the Particle Therapy Cooperative Group North America (PTCOG-NA): 14-16 October 2019, Hosted by Miami Cancer Institute, part of Baptist Health South Florida, Miami, FL, USA.