Pub Date : 2024-07-30DOI: 10.3389/fphy.2024.1393130
Rudolf Zeller
The irregular solutions of the stationary Schrödinger equation are important for the fundamental formal development of scattering theory. They are also necessary for the analytical properties of the Green function, which in practice can greatly speed up calculations. Nevertheless, they are seldom considered in numerical treatments because of their divergent behavior at origin. This divergence demands high numerical precision that is difficult to achieve, particularly for non-spherical potentials which lead to different divergence rates in the coupled angular momentum channels. Based on an unconventional treatment of boundary conditions, an integral-equation method is here developed which is capable of dealing with this problem. The available precision is illustrated by electron-density calculations for NiTi in its monoclinic B19’ structure.
{"title":"On the calculation of irregular solutions of the Schrödinger equation for non-spherical potentials with applications to metallic alloys","authors":"Rudolf Zeller","doi":"10.3389/fphy.2024.1393130","DOIUrl":"https://doi.org/10.3389/fphy.2024.1393130","url":null,"abstract":"The irregular solutions of the stationary Schrödinger equation are important for the fundamental formal development of scattering theory. They are also necessary for the analytical properties of the Green function, which in practice can greatly speed up calculations. Nevertheless, they are seldom considered in numerical treatments because of their divergent behavior at origin. This divergence demands high numerical precision that is difficult to achieve, particularly for non-spherical potentials which lead to different divergence rates in the coupled angular momentum channels. Based on an unconventional treatment of boundary conditions, an integral-equation method is here developed which is capable of dealing with this problem. The available precision is illustrated by electron-density calculations for NiTi in its monoclinic B19’ structure.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"74 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141864259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-29DOI: 10.3389/fphy.2024.1417293
Jawad Mirza, Firdos Kanwal, Umair Ahmad Salaria, Salman Ghafoor, Imran Aziz, Ahmad Atieh, Ahmad Almogren, Anwar Ul Haq, Benish Kanwal
The safety of SCUBA divers remains at high risk in deep-sea owing to multiple factors such as dangerous surrounding, rely upon technical equipment necessary for life support, decreased underwater navigation, and communication infrastructure. Gradual decrease and increase in water temperature and pressure corresponding to depth are among the most common problems that cause most of the fatalities in deep-sea diving. Therefore, different gadgets for accurate measurement of vital parameters, reliable navigation, and seamless communication are of prime importance. In this paper, we propose an all-optical technique for local and remote monitoring of underwater temperature and pressure for deep-sea SCUBA divers based on fiber Bragg grating (FBG) sensors and underwater optical communication-single mode fiber (UWOC-SMF) integrated transmission system. The proposed technique is implemented using two FBG temperature and pressure sensors fixed over diver’s suit and UWOC-SMF integrated transmission system for simultaneous local and remote monitoring of underwater temperature and pressure. Remote monitoring of underwater temperature and pressure is achieved at ship station through a remotely operated underwater vehicle (ROV) and UWOC-SMF integrated transmission system by means of shifts in the original Bragg wavelengths of sensors due to temperature and pressure variations. The performance of the sensors is analyzed for pressure and temperature in the range of 0 to 6.4 MPa (≈0 to 655 mH2O) and 40 to −2°C, respectively corresponding to different depths. The results show that the proposed technique can work well in the deep ocean over a range of pressures and temperatures of 0–7 MPa and 40 to −2°C while achieving a temperature sensitivity of 4.3 p.m./°C and a pressure sensitivity of 30.5 p.m./MPa. Clear spectra of reflected signals from FBG sensors at ship station are achieved after signal transmission over UWOC-SMF hybrid link.
{"title":"Underwater temperature and pressure monitoring for deep-sea SCUBA divers using optical techniques","authors":"Jawad Mirza, Firdos Kanwal, Umair Ahmad Salaria, Salman Ghafoor, Imran Aziz, Ahmad Atieh, Ahmad Almogren, Anwar Ul Haq, Benish Kanwal","doi":"10.3389/fphy.2024.1417293","DOIUrl":"https://doi.org/10.3389/fphy.2024.1417293","url":null,"abstract":"The safety of SCUBA divers remains at high risk in deep-sea owing to multiple factors such as dangerous surrounding, rely upon technical equipment necessary for life support, decreased underwater navigation, and communication infrastructure. Gradual decrease and increase in water temperature and pressure corresponding to depth are among the most common problems that cause most of the fatalities in deep-sea diving. Therefore, different gadgets for accurate measurement of vital parameters, reliable navigation, and seamless communication are of prime importance. In this paper, we propose an all-optical technique for local and remote monitoring of underwater temperature and pressure for deep-sea SCUBA divers based on fiber Bragg grating (FBG) sensors and underwater optical communication-single mode fiber (UWOC-SMF) integrated transmission system. The proposed technique is implemented using two FBG temperature and pressure sensors fixed over diver’s suit and UWOC-SMF integrated transmission system for simultaneous local and remote monitoring of underwater temperature and pressure. Remote monitoring of underwater temperature and pressure is achieved at ship station through a remotely operated underwater vehicle (ROV) and UWOC-SMF integrated transmission system by means of shifts in the original Bragg wavelengths of sensors due to temperature and pressure variations. The performance of the sensors is analyzed for pressure and temperature in the range of 0 to 6.4 MPa (<jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mo>≈</mml:mo></mml:math></jats:inline-formula>0 to 655 <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:msub><mml:mrow><mml:mi mathvariant=\"normal\">m</mml:mi><mml:mi mathvariant=\"normal\">H</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mi>O</mml:mi></mml:math></jats:inline-formula>) and 40 to −2<jats:italic>°C</jats:italic>, respectively corresponding to different depths. The results show that the proposed technique can work well in the deep ocean over a range of pressures and temperatures of 0–7 MPa and 40 to −2<jats:italic>°C</jats:italic> while achieving a temperature sensitivity of 4.3 p.m./<jats:italic>°</jats:italic>C and a pressure sensitivity of 30.5 p.m./MPa. Clear spectra of reflected signals from FBG sensors at ship station are achieved after signal transmission over UWOC-SMF hybrid link.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"37 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141864255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As a promising sensing material, Molybdenum disulfide (MoS2) nanosheets is being increasingly studied for Nitrogen dioxide (NO2) gas sensing. However, the MoS2 nanosheets is prone to the stacking effect that compromises the sensing performances. Here, the stacking effect is mitigated by engineering MoS2 nanosheets into a three dimensional (3D) network microstructure, which was fabricated by method of electrostatically self-assembling of MoS2/SiO2 microspheres. The fabricated sensor based on 3D MoS2 network observed a significantly improved response of 15% to 12.3 ppm NO2, which is a 75-fold increase compared to the control sensor with pure MoS2 nanosheets. In addition, the sensitivity of the sensor with 3D MoS2 network was 6.15 times larger than that of the control sensor with pure MoS2 nanosheets. The detection limit of our sensor was 0.297 ppm, lower than most of reported MoS2-based NO2 sensors. The enhanced sensitivity and dynamic response stem from the improved interaction between NO2 molecules and MoS2 network, thanks to its increased surface area per footprint of MoS2 nanosheets compared to pure 2D MoS2 film (single- or few-layer). This work presents a new approach to enhancing the performance of gas sensors based on 2D materials.
{"title":"Enhanced sensing response of the three dimensional MoS2 microstructure for NO2 gas detection at room temperature","authors":"Hongdao Cheng, Sihuan Huang, Zengshan Xing, Lu Yang, Jianhui Yu, Yongchun Zhong","doi":"10.3389/fphy.2024.1446416","DOIUrl":"https://doi.org/10.3389/fphy.2024.1446416","url":null,"abstract":"As a promising sensing material, Molybdenum disulfide (MoS<jats:sub>2</jats:sub>) nanosheets is being increasingly studied for Nitrogen dioxide (NO<jats:sub>2</jats:sub>) gas sensing. However, the MoS<jats:sub>2</jats:sub> nanosheets is prone to the stacking effect that compromises the sensing performances. Here, the stacking effect is mitigated by engineering MoS<jats:sub>2</jats:sub> nanosheets into a three dimensional (3D) network microstructure, which was fabricated by method of electrostatically self-assembling of MoS<jats:sub>2</jats:sub>/SiO<jats:sub>2</jats:sub> microspheres. The fabricated sensor based on 3D MoS<jats:sub>2</jats:sub> network observed a significantly improved response of 15% to 12.3 ppm NO<jats:sub>2</jats:sub>, which is a 75-fold increase compared to the control sensor with pure MoS<jats:sub>2</jats:sub> nanosheets. In addition, the sensitivity of the sensor with 3D MoS<jats:sub>2</jats:sub> network was 6.15 times larger than that of the control sensor with pure MoS<jats:sub>2</jats:sub> nanosheets. The detection limit of our sensor was 0.297 ppm, lower than most of reported MoS<jats:sub>2</jats:sub>-based NO<jats:sub>2</jats:sub> sensors. The enhanced sensitivity and dynamic response stem from the improved interaction between NO<jats:sub>2</jats:sub> molecules and MoS<jats:sub>2</jats:sub> network, thanks to its increased surface area per footprint of MoS<jats:sub>2</jats:sub> nanosheets compared to pure 2D MoS<jats:sub>2</jats:sub> film (single- or few-layer). This work presents a new approach to enhancing the performance of gas sensors based on 2D materials.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"59 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141864256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-26DOI: 10.3389/fphy.2024.1369574
Tito Körner, Stefan Wampl, Lorenz Kiss, Gunpreet Oberoi, Ewald Unger, Wolfgang Birkfellner, Albrecht I. Schmid
IntroductionPhantoms mimicking tissue motion have become a valuable tool for quality control in various fields of medical physics including lung phantoms for image-guided radiotherapy and functional imaging in nuclear medicine or magnetic resonance imaging (MRI) in the body. In MRI, precise kinematic models are more difficult to realize owing to the requirements of MR-compatibility. Pneumatic stepper motors built entirely of non-conducting materials can be safely used in an MR environment, with pressurized air supply and switching residing outside the magnet room.MethodsIn this research, a torso phantom was built adopting a 3D-printed linear stepper drive for use with high-field MR scanners. It was possible to simulate respiratory motion of a 3D-printed left ventricle phantom using the stepper.Results and discussionPrecise and accurate motion for a time of 15 min over a range of 8 cm were achieved with speeds up to 5.5 mm/s when the stepper was loaded with the left ventricle phantom. It was shown that the motor is an effective tool for quality control in multi-modal medical imaging.
{"title":"A modular torso phantom featuring a pneumatic stepper and flow for MR sequence development","authors":"Tito Körner, Stefan Wampl, Lorenz Kiss, Gunpreet Oberoi, Ewald Unger, Wolfgang Birkfellner, Albrecht I. Schmid","doi":"10.3389/fphy.2024.1369574","DOIUrl":"https://doi.org/10.3389/fphy.2024.1369574","url":null,"abstract":"IntroductionPhantoms mimicking tissue motion have become a valuable tool for quality control in various fields of medical physics including lung phantoms for image-guided radiotherapy and functional imaging in nuclear medicine or magnetic resonance imaging (MRI) in the body. In MRI, precise kinematic models are more difficult to realize owing to the requirements of MR-compatibility. Pneumatic stepper motors built entirely of non-conducting materials can be safely used in an MR environment, with pressurized air supply and switching residing outside the magnet room.MethodsIn this research, a torso phantom was built adopting a 3D-printed linear stepper drive for use with high-field MR scanners. It was possible to simulate respiratory motion of a 3D-printed left ventricle phantom using the stepper.Results and discussionPrecise and accurate motion for a time of 15 min over a range of 8 cm were achieved with speeds up to 5.5 mm/s when the stepper was loaded with the left ventricle phantom. It was shown that the motor is an effective tool for quality control in multi-modal medical imaging.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"37 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141777744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-26DOI: 10.3389/fphy.2024.1398172
Trang Le, Yasuhiro Suzuki, Hiroaki Ohtani, Hiroki Hasegawa, Toseo Moritaka
To study the symmetry of electrical potential, we model plasma transport in the edge region of a toroidal device with two spatial dimensions (2D) and three coordinates for velocities (3V) using a Particle-In-Cell (PIC) code. A two-dimensional magnetic field is applied, including poloidal and toroidal components, which are periodic in the poloidal direction. We discover relationships between the magnetic gradient drift and potential formation using PIC simulation, which has not been captured in other numerical models. We find that the inverse aspect ratio influences the asymmetry of the potential in an axisymmetric magnetic configuration.
{"title":"Frontiers | Poloidally asymmetric potential formation on plasma boundary in axisymmetric magnetic field","authors":"Trang Le, Yasuhiro Suzuki, Hiroaki Ohtani, Hiroki Hasegawa, Toseo Moritaka","doi":"10.3389/fphy.2024.1398172","DOIUrl":"https://doi.org/10.3389/fphy.2024.1398172","url":null,"abstract":"To study the symmetry of electrical potential, we model plasma transport in the edge region of a toroidal device with two spatial dimensions (2D) and three coordinates for velocities (3V) using a Particle-In-Cell (PIC) code. A two-dimensional magnetic field is applied, including poloidal and toroidal components, which are periodic in the poloidal direction. We discover relationships between the magnetic gradient drift and potential formation using PIC simulation, which has not been captured in other numerical models. We find that the inverse aspect ratio influences the asymmetry of the potential in an axisymmetric magnetic configuration.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"1 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141945751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-25DOI: 10.3389/fphy.2024.1444297
Arturo Mendoza-Galván, Roger Magnusson, Nicklas Jansson, Hans Arwin, Kenneth Järrendahl
Many species of beetles from the family Scarabaeidae reflect light with near-circular polarization. In some cases, spectral narrow-band polarization phenomena result in a distinct color with a metallic shine. In other cases, broad-band features are seen, and these beetles have a silvery or goldish appearance. These features in the cuticles originate from helicoidal structures, so-called circular Bragg structures and also referred to as Bouligand structures. In this communication, Protaetia mirifica, exhibiting near-circular polarization properties in dual spectral regions, centered approximately at the wavelengths of 474 and 770 nm, is investigated in considerable detail using Mueller matrix spectroscopic ellipsometry (MMSE). From interference oscillations in the MMSE spectra, the pitch profile of the helicoidal structures in the beetle cuticle is extracted and further used in electromagnetic modeling of the cuticle structure, including the determination of epicuticle and exocuticle thicknesses (280 nm and 8.1 μm, respectively) and anisotropic optical properties. These findings are confirmed by scanning electron microscopy. The analysis shows that the uppermost 4μm of the cuticle has a nearly constant pitch of 310 nm, which abruptly jumps to 440 nm and then gradually increases up to 575 nm. Sum decompositions of MMSE spectra reveal that the beetle cuticle reflects like a circular polarizer or like a dielectric mirror, depending on the spectral region.
{"title":"Dual chiral structures in the cuticle of Protaetia mirifica analyzed with Mueller matrix spectroscopic ellipsometry","authors":"Arturo Mendoza-Galván, Roger Magnusson, Nicklas Jansson, Hans Arwin, Kenneth Järrendahl","doi":"10.3389/fphy.2024.1444297","DOIUrl":"https://doi.org/10.3389/fphy.2024.1444297","url":null,"abstract":"Many species of beetles from the family Scarabaeidae reflect light with near-circular polarization. In some cases, spectral narrow-band polarization phenomena result in a distinct color with a metallic shine. In other cases, broad-band features are seen, and these beetles have a silvery or goldish appearance. These features in the cuticles originate from helicoidal structures, so-called circular Bragg structures and also referred to as Bouligand structures. In this communication, <jats:italic>Protaetia mirifica,</jats:italic> exhibiting near-circular polarization properties in dual spectral regions, centered approximately at the wavelengths of 474 and 770 nm, is investigated in considerable detail using Mueller matrix spectroscopic ellipsometry (MMSE). From interference oscillations in the MMSE spectra, the pitch profile of the helicoidal structures in the beetle cuticle is extracted and further used in electromagnetic modeling of the cuticle structure, including the determination of epicuticle and exocuticle thicknesses (280 nm and 8.1 <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:mi>μ</mml:mi><mml:mi mathvariant=\"normal\">m</mml:mi></mml:mrow></mml:math></jats:inline-formula>, respectively) and anisotropic optical properties. These findings are confirmed by scanning electron microscopy. The analysis shows that the uppermost <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:mn>4</mml:mn><mml:mtext> </mml:mtext><mml:mi>μ</mml:mi><mml:mi mathvariant=\"normal\">m</mml:mi></mml:mrow></mml:math></jats:inline-formula> of the cuticle has a nearly constant pitch of 310 nm, which abruptly jumps to 440 nm and then gradually increases up to 575 nm. Sum decompositions of MMSE spectra reveal that the beetle cuticle reflects like a circular polarizer or like a dielectric mirror, depending on the spectral region.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"62 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141777745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-24DOI: 10.3389/fphy.2024.1400730
Ayman Elsharkawy, Noha Elsharkawy
The Frenet frame is not suitable for describing the behavior of the curve in the Galilean space since it is not defined everywhere. In this study, an alternative frame, the so-called quasi-frame, is investigated in Galilean 4-space. Furthermore, the quasi-formulas in Galilean 4-space are deduced and quasi-curvatures are obtained in terms of the quasi-frame and its derivatives. Quasi-rectifying, quasi-normal, and quasi-osculating curves are studied in Galilean 4-space. We prove that there is no quasi-normal and accordingly normal curve in Galilean 4-space.
{"title":"Quasi-position vector curves in Galilean 4-space","authors":"Ayman Elsharkawy, Noha Elsharkawy","doi":"10.3389/fphy.2024.1400730","DOIUrl":"https://doi.org/10.3389/fphy.2024.1400730","url":null,"abstract":"The Frenet frame is not suitable for describing the behavior of the curve in the Galilean space since it is not defined everywhere. In this study, an alternative frame, the so-called quasi-frame, is investigated in Galilean 4-space. Furthermore, the quasi-formulas in Galilean 4-space are deduced and quasi-curvatures are obtained in terms of the quasi-frame and its derivatives. Quasi-rectifying, quasi-normal, and quasi-osculating curves are studied in Galilean 4-space. We prove that there is no quasi-normal and accordingly normal curve in Galilean 4-space.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"21 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141777746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-24DOI: 10.3389/fphy.2024.1359179
Matteo Centis Vignali, Giovanni Paternoster
Low Gain Avalanche Diodes (LGADs) are silicon sensors designed to achieve an internal gain in the order of 10 through the impact ionization process. The development of LGADs was pushed forward by their application in High Energy Physics (HEP) experiments, where they will be employed to provide measurements of the time of arrival of minimum ionizing particles with a resolution of around 30 ps. The initial technological implementation of the sensors constrains their minimum channel size to be larger than 1 mm2, in order to reduce inefficiencies due to the segmentation of the gain structure. The gain of the sensors is kept in the order of 10 to limit the sensor shot noise and their power consumption. In photon science, the gain provided by the sensor can boost the signal-to-noise ratio of the detector system, effectively reducing the x-ray energy threshold of photon counting detectors and the minimum x-ray energy where single photon resolution is achieved in charge integrating detectors. This can improve the hybrid pixel and strip detectors for soft and tender x-rays by simply changing the sensor element of the detector system. Photon science applications in the soft and tender energy range require improvements over the LGADs developed for HEP, in particular the presence of a thin entrance window to provide a satisfactory quantum efficiency and channel size with a pitch of less than 100 μm. In this review, the fundamental aspects of the LGAD technology are presented, discussing also the ongoing and future developments that are of interest for photon science applications.
低增益雪崩二极管（LGAD）是一种硅传感器，其设计目的是通过撞击电离过程实现 10 量级的内部增益。低增益雪崩二极管在高能物理（HEP）实验中的应用推动了低增益雪崩二极管的发展，在高能物理实验中，低增益雪崩二极管将用于测量最小电离粒子的到达时间，分辨率约为 30 ps。传感器最初的技术实施限制其最小通道尺寸大于 1 平方毫米，以减少增益结构分段造成的低效。传感器的增益保持在 10 的数量级，以限制传感器的射击噪声和功耗。在光子科学中，传感器提供的增益可以提高探测器系统的信噪比，有效降低光子计数探测器的 X 射线能量阈值和电荷积分探测器实现单光子分辨率的最小 X 射线能量。这样，只需改变探测器系统的传感器元件，就能改进用于软X射线和嫩X射线的混合像素和条带探测器。软X射线和嫩X射线能量范围内的光子科学应用需要改进为高能量X射线开发的 LGAD，特别是需要薄入口窗口，以提供令人满意的量子效率和间距小于 100 微米的通道尺寸。本综述介绍了 LGAD 技术的基本方面，并讨论了光子科学应用方面正在进行的和未来的发展。
{"title":"Low gain avalanche diodes for photon science applications","authors":"Matteo Centis Vignali, Giovanni Paternoster","doi":"10.3389/fphy.2024.1359179","DOIUrl":"https://doi.org/10.3389/fphy.2024.1359179","url":null,"abstract":"Low Gain Avalanche Diodes (LGADs) are silicon sensors designed to achieve an internal gain in the order of 10 through the impact ionization process. The development of LGADs was pushed forward by their application in High Energy Physics (HEP) experiments, where they will be employed to provide measurements of the time of arrival of minimum ionizing particles with a resolution of around 30 ps. The initial technological implementation of the sensors constrains their minimum channel size to be larger than 1 mm<jats:sup>2</jats:sup>, in order to reduce inefficiencies due to the segmentation of the gain structure. The gain of the sensors is kept in the order of 10 to limit the sensor shot noise and their power consumption. In photon science, the gain provided by the sensor can boost the signal-to-noise ratio of the detector system, effectively reducing the x-ray energy threshold of photon counting detectors and the minimum x-ray energy where single photon resolution is achieved in charge integrating detectors. This can improve the hybrid pixel and strip detectors for soft and tender x-rays by simply changing the sensor element of the detector system. Photon science applications in the soft and tender energy range require improvements over the LGADs developed for HEP, in particular the presence of a thin entrance window to provide a satisfactory quantum efficiency and channel size with a pitch of less than 100 <jats:italic>μ</jats:italic>m. In this review, the fundamental aspects of the LGAD technology are presented, discussing also the ongoing and future developments that are of interest for photon science applications.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"329 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141777748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-24DOI: 10.3389/fphy.2024.1424995
Qian Hu, Chengmiao Liu
An effective formula for the shape-sensitivity analysis of electromagnetic scattering is presented in this paper. First, based on the boundary element method, a new electromagnetic scattering formula is derived by combining the traditional electromagnetic scattering formula with the non-uniform rational B-spline (NURBS) curve, and the geometric model is represented by NURBS, which ensures the geometric accuracy, avoids the heavy grid division in the optimization process, and realizes the fast calculation of high-fidelity numerical solutions. Second, by deducing the sensitivity variables, the electromagnetic scattering equation of shape optimization is obtained, which can provide reliable data references for shape optimization. Finally, the effectiveness and accuracy of the algorithm are demonstrated by an example, and the sensitivity data of some examples are given.
本文提出了一种有效的电磁散射形状敏感性分析公式。首先，基于边界元法，将传统电磁散射公式与非均匀有理 B 样条曲线（NURBS）相结合，推导出新的电磁散射公式，并用 NURBS 表示几何模型，保证了几何精度，避免了优化过程中繁重的网格划分，实现了高保真数值解的快速计算。其次，通过推导灵敏度变量，得到形状优化的电磁散射方程，为形状优化提供可靠的数据参考。最后，通过实例证明了算法的有效性和准确性，并给出了一些实例的灵敏度数据。
{"title":"Two-dimensional electromagnetic scattering analysis based on the boundary element method","authors":"Qian Hu, Chengmiao Liu","doi":"10.3389/fphy.2024.1424995","DOIUrl":"https://doi.org/10.3389/fphy.2024.1424995","url":null,"abstract":"An effective formula for the shape-sensitivity analysis of electromagnetic scattering is presented in this paper. First, based on the boundary element method, a new electromagnetic scattering formula is derived by combining the traditional electromagnetic scattering formula with the non-uniform rational B-spline (NURBS) curve, and the geometric model is represented by NURBS, which ensures the geometric accuracy, avoids the heavy grid division in the optimization process, and realizes the fast calculation of high-fidelity numerical solutions. Second, by deducing the sensitivity variables, the electromagnetic scattering equation of shape optimization is obtained, which can provide reliable data references for shape optimization. Finally, the effectiveness and accuracy of the algorithm are demonstrated by an example, and the sensitivity data of some examples are given.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"16 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141777749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-23DOI: 10.3389/fphy.2024.1327161
Mengna Zhang, Liming Liu, Yingxu Wang
Introduction: Studying the main factors and related paths of rumor propagation contributes to the precise governance of rumor information in social networks. Most existing network representation learning methods do not fit with real-world information propagation networks well, and the network cannot effectively model the temporal characteristics and dynamic evolution features of rumor information propagation.Methods: Our study proposes a new dynamic network representation model for information propagation. Additionally, the study introduces a feedback mechanism where the latest node representations are fed back to neighboring nodes.Results: The method solves the problem of delayed network representation and improves network representation performance.Discussion: We conducted experimental simulations, and the results indicate that a higher level of trust contributes to stable group relationships and converging opinions, reducing the likelihood of opinion dispersion. Furthermore, novelty of topics, and interactivity between users, and opinion leaders exhibit distinct characteristics in guiding public opinion. The viewpoint evolution of the newly constructed dynamic network representation model aligns more closely with viewpoint evolution in real-world social networks.
{"title":"Research on the dynamic spread of information in social networks based on relationship strength theory and feedback mechanism","authors":"Mengna Zhang, Liming Liu, Yingxu Wang","doi":"10.3389/fphy.2024.1327161","DOIUrl":"https://doi.org/10.3389/fphy.2024.1327161","url":null,"abstract":"Introduction: Studying the main factors and related paths of rumor propagation contributes to the precise governance of rumor information in social networks. Most existing network representation learning methods do not fit with real-world information propagation networks well, and the network cannot effectively model the temporal characteristics and dynamic evolution features of rumor information propagation.Methods: Our study proposes a new dynamic network representation model for information propagation. Additionally, the study introduces a feedback mechanism where the latest node representations are fed back to neighboring nodes.Results: The method solves the problem of delayed network representation and improves network representation performance.Discussion: We conducted experimental simulations, and the results indicate that a higher level of trust contributes to stable group relationships and converging opinions, reducing the likelihood of opinion dispersion. Furthermore, novelty of topics, and interactivity between users, and opinion leaders exhibit distinct characteristics in guiding public opinion. The viewpoint evolution of the newly constructed dynamic network representation model aligns more closely with viewpoint evolution in real-world social networks.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"216 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141777750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：