检索结果-内蒙古大学图书馆

Doppler backscattering systems on the Globus-M2 tokamak

JOURNAL OF INSTRUMENTATION 2022年第1期17卷 C01023-C01023页

作者： Yashin, A. Y. Bulanin, V. V. Gusev, V. K. Minaev, V. B. Petrov, A., V Petrov, Y., V Ponomarenko, A. M. Varfolomeev, V., I Peter Great St Petersburg Polytech Univ St Petersburg Russia Ioffe Inst St Petersburg Russia

Doppler backscattering (DBS) was successfully previously used on the Globus-M tokamak. The diagnostic was utilised in the form of either a single-frequency or a four-frequency dual homodyne system. It was used primarily for the study of zonal flows, filaments and Alfve acute accent n eigenmodes. These phenomena are worth being studied both on the periphery and in the core region of the plasma in a tokamak. For this specific reason two multifrequency DBS systems were installed on the upgraded Globus-M2 tokamak. The first four-frequency system with dual homodyne detection had already been used on the Globus-M tokamak and has lower probing frequencies which provide measurements from the periphery plasma. The second and new six frequency DBS system was installed with a non-linear transmission line that was adapted to generate probing signals at frequencies 50, 55, 60, 65, 70 and 75 GHz. In general, the range of probing frequencies corresponds to the region of critical plasma densities from 5 x 10(18) to 7 x 10(19) m(-3) at normal incidence. The pyramidal horn antennas are located inside the vacuum vessel with a special cardan-like rotator outside the camera so as to tilt antennas in the toroidal and poloidal directions. A previously developed code was applied to simulate 3D raytracing for all frequency channels. Calculations were carried out for different angles of incidence and for different electron density distributions in order to investigate the possibilities of the implementation of radial and poloidal correlation Doppler reflectometry. Examples of the DBS system application for study of plasma properties in the Globus-M2 tokamak are presented.

关键词： Nuclear instruments and methods for hot plasma diagnostics data processing methods

来源：评论

学校读者我要写书评

暂无评论

Machine learning for track reconstruction at the LHC

引用

JOURNAL OF INSTRUMENTATION 2022年第2期17卷

作者： Gagnon, L. -G. Univ Calif Berkeley Berkeley CA 94720 USA

The planned upgrade of the LHC to its High-Luminosity counterpart (HL-LHC) circa 2027 will bring about a drastic increase in instantaneous luminosity, pileup, and trigger rates. Currently, most LHC experiments use Kalman filter based track reconstruction algorithms which exhibit outstanding physics performance but scale poorly with the amount of data produced per bunch crossing. Therefore, the high energy physics community is currently performing intensive R & D to commission new or improved algorithms for this crucial data reconstruction task. This article presents many approaches such as running existing Kalman filter algorithms on accelerated hardware and overhauling the current approaches with machine learning techniques. A new algorithm testbed for research in track reconstruction, ACTS, is also discussed.

关键词： Particle tracking detectors Pattern recognition cluster finding calibration and fitting methods Analysis and statistical methods data processing methods

来源：评论

学校读者我要写书评

暂无评论

Application of 2 x 5 MPX3 camera with monolithic sensor for phase contrast imaging and computed tomography

引用

JOURNAL OF INSTRUMENTATION 2022年第3期17卷 C03020页

作者： Vavrik, D. Dudak, J. Kumpova, I Zemlicka, J. Czech Acad Sci Inst Theoret & Appl Mech Prosecka 76 Prague 6 Czech Republic Czech Tech Univ Inst Expt & Appl Phys Husova 240-5 Prague 1 Czech Republic

This work focuses on the non-destructive identification of delamination in layered structures utilizing the X-ray phase contrast effect. This effect naturally occurs on sharp edges, material interfaces and fine textures, and can be retrieved from radiographic data even without any grating in special cases, as will be demonstrated for the layered carbon fibre reinforced plastic composites used in the aerospace industry. Such delamination can be described as the local disbonding of composite layers, which often occurs due to the cyclic loading of the structural elements while in service. Such a flaw may significantly decrease its bearing capacity, and therefore periodic non-destructive inspection is needed. Aside from ultrasound inspection, which provides limited resolution and detectability, X-ray imaging and tomography is widely used in practise. Nevertheless, the identification of delamination may be difficult utilizing X-ray computed tomography, as delaminated faces may remain in contact - the defect has negligible volume. On the other hand, the distance between faces is not relevant for X-ray phase contrast imaging. In addition, access to the structural elements is often limited for X-ray imaging. For shaped parts, it will be shown in this work that limited access is not as critical a problem in comparison with standard computed tomography.

关键词： data processing methods Detection of defects Image filtering Inspection with X-rays

来源：评论

学校读者我要写书评

暂无评论

Teaching machine learning with an application in collider particle physics

引用

JOURNAL OF INSTRUMENTATION 2020年第9期15卷

作者： Benato, L. Connor, P. L. S. Kasieczka, G. Kruecker, D. Meyer, M. Univ Hamburg Inst Expt Phys Hamburg Germany DESY Hamburg Germany

We describe a hands-on introduction to deep learning in particle physics, performed during the 5th INFIERI school in Wuhan, China. We presented fundamental machine learning concepts to students from diverse backgrounds in physics and computing, and prepared them to apply these techniques to solve an example problem from particle physics (hadronic top quark tagging). We exploited the simplicity of tools like Jupyter notebooks, and the user-friendly approaches of data science libraries such as Keras with TensorFlow.

关键词： Analysis and statistical methods Computing (architecture, farms, GRID for recording, storage, archiving, and distribution of data) data processing methods Software architectures (event data models, frameworks and databases)

来源：评论

学校读者我要写书评

暂无评论

Reversed-slit spectroscopy method for in situ measurement of H isotopes on plasma facing material

引用

JOURNAL OF INSTRUMENTATION 2020年第1期15卷

作者： Jiang, X. Sergienko, G. Kreter, A. Brezinsek, S. Linsmeier, Ch. Forschungszentrum Julich Inst Energie & Klimaforsch Plasmaphys D-52425 Julich Germany

Optic spectroscopy methods are employed for plasma facing component (PFC) material diagnostics and H isotopes retention on various platforms. A common issue of those spectroscopy methods is the measurement sensitivity. Various improvement methods have been investigated. In the current work, a 'reversed-slit' method is explored, aiming to maximise signal input while retain a reasonably good line resolution. A thin metal wire with a diameter that is comparable to a normal slit width is placed in front of an open slit. By opening the slit the input of the emission light is maximised. The thin wire casts a line of shadow on the spectral image. The shadow line is used as the 'characteristic line' to identify and separate the spectral line of each H isotope. The result shows that an open slit of 3 mm width can bring an intensity increase of 20-30 times compared to a 100 mu m wide normal slit without compromising the resolution.

关键词： Optics Spectrometers data processing methods Detector design and construction technologies and materials

来源：评论

学校读者我要写书评

暂无评论

Improvement of a spectrum-to-dose conversion function for electronic personal dosimeters

引用

JOURNAL OF INSTRUMENTATION 2020年第2期15卷

作者： Park, K. Kim, J. Lim, K. T. Kim, G. Lee, M. Kim, H. Cho, G. Korea Adv Inst Sci & Technol Dept Nucl & Quantum Engn 291 Daehak Ro Daejeon 34141 South Korea IRIS Co Ltd 193 Munji Ro Daejeon 34051 South Korea

For electronic personal dosimeters (EPDs) based on a spectroscopy system, it is necessary to accurately measure the dose in real-time from the gamma energy spectra. The method of spectrum-to-dose conversion is being used instead of the method of count-to-dose conversion. The G(E) function, a typical method of spectrum-to-dose conversion has been applied to various instruments due to its good dose measurement performance and the advantage of real-time measurements. In this manuscript, we present a method to increase the accuracy of G(E) function for the EPD consisting of a 3 x 3 mm(2) PIN diode coupled with a 3 x 3 x 3 mm(3) CsI(Tl) scintillator. The new G(E) function was calculated using the adaptive moment estimation (ADAM) method based on Monte Carlo simulation. The proposed G(E) function is verified by comparison with the least-square method (LSM), which is the conventional method for calculating the G(E) function and with the gradient-descent method (GDM), which is the basis for the ADAM. The relative difference was acquired to compare the converted dose value using each G(E) function by using Am-241, Co-57, Na-22, Cs-137, Mn-54 and Co-60 radioisotopes. In addition, the energy response to Cs-137 of each G(E) function was obtained. The relative difference of G(E) function according to LSM, GDM, and ADAM was in the range of +/- 28.54, +/- 12.59, and +/- 9.9%, respectively, and the energy response to Cs-137 was 0.71 to 1, 0.87 to 1.02, and 0.9 to 1.03, respectively.

关键词： Dosimetry concepts and apparatus Analysis and statistical methods data processing methods Models and simulations

来源：评论

学校读者我要写书评

暂无评论

Study of neutron-rich isotopes near N=152 shell closure using Timepix type detectors integrated into the mass separator MASHA

引用

JOURNAL OF INSTRUMENTATION 2020年第2期15卷

作者： Broulim, J. Chernysheva, E. V. Gulyaev, S. N. Gulyaeva, A. V. Holik, M. Kamas, D. Kliman, J. Komarov, A. B. Krupa, L. Mora, Y. Novoselov, A. S. Opichal, A. Pechousek, J. Podshibyakin, A. V. Rodin, A. M. Salamatin, V. S. Stepantsov, S. V. Vedeneev, V. Yu. Yukhimchuk, S. A. Joint Inst Nucl Res Flerov Lab Nucl React Joliot Curie 6 Dubna 141980 Moscow Region Russia Slovak Acad Sci Inst Phys Dubravska Cesta 9 Bratislava 84228 Slovakia Czech Tech Univ Inst Expt & Appl Phys Husova 240-5 Prague 11000 1 Czech Republic Palacky Univ Olomouc Fac Sci 17 Listopadu 1192-12 Olomouc 77900 Czech Republic Univ West Bohemia Pilsen Fac Elect Engn Univ 26 Plzen 30100 Czech Republic

The MASHA facility [1-3] was developed as a high precision mass-spectrometer for heavy and super heavy elements with masses up to 450 a.m.u. It uses ISOL (Isotope Separation On-Line) method. Its unique properties opens great prospective for the investigation of neutron-rich nuclei produced in multinucleon transfer reactions. Mainly nuclei near the neutron N = 126 and N = 152 shell closures are of great interest. This region of nuclei is not so far thoroughly enough investigated while its research has direct relation to the synthesis of super heavy elements. As is known the island of stability close to super heavy elements (Z = 112-118) exists due to the shell effects in nuclei. More detailed investigation of these shell effects can greatly help in the synthesis of next super heavy elements. Heavy neutron rich radon isotopes were produced in the multinucleon transfer reaction Ar-40 + Th-232 at Flerov Laboratory of Nuclear Reactions, Dubna. Radon isotopes with given masses were detected using two types of detectors: a multi-strip well-type detector (made in Canberra) and a position-sensitive quantum counting hybrid pixel detector of the Timepix type [4]. The latter detector has an array of 256x256 square pixels each with a pitch size of 55 mu m for the full sensitive area 14x14mm(2). Radon isotopes implanted into the detector emit then alpha and beta particles until they reach the stable or long-lived isotopes at the end of their decay chains. The positions of radon isotopes, the tracks, times and energies of the beta particles were measured and analyzed. New software for the particle recognition and data analysis of the results obtained from the experiment was developed and used. It has been proven that MASHA + Timepix setup is a powerful instrument for investigation of neutron-rich isotopes far from stability limits.

关键词： Particle identification methods Particle tracking detectors data processing methods data acquisition concepts

来源：评论

学校读者我要写书评

暂无评论

Polar-coordinate-based data analysis scheme for high-voltage measurement system using the Pockels electro-optic effect

引用

JOURNAL OF INSTRUMENTATION 2020年第3期15卷

作者： Choi, S. Sugianto, A. A. Lee, D-G Woo, H. J. Hong, S. H. Ghim, Y-C Korea Adv Inst Sci & Technol Dept Nucl & Quantum Engn Daejeon South Korea Korea Adv Inst Sci & Technol Dept Phys Daejeon South Korea Agcy Def Dev Daejeon South Korea Hanyang Univ Dept Elect & Engn Seoul South Korea

A voltage measurement system based on the Pockels electro-optic effect typically has, due to a half-wave voltage V-pi of a Pockels cell, a limitation on the unambiguous measurable range. To overcome such a limitation, we develop a polar-coordinate-based data analysis scheme with a simultaneous measurement of cos (pi V/V-pi) and sin (pi V/V-pi), where V is the voltage the Pockels cell experiences, i.e., the voltage we wish to measure. The developed data analysis scheme also corrects, without knowledge of V-pi, a misalignment of the Pockels cell and an imbalanced transmittance of a beam splitter between the horizontal and vertical components of the polarized laser beam. Thus, increased accuracy of not only the V-pi measurement during calibration procedure but also the voltage measurement itself is also achieved.

关键词： data processing methods Analysis and statistical methods Detector alignment and calibration methods (lasers, sources, particle-beams)

来源：评论

学校读者我要写书评

暂无评论

Experimental observations of local plasma parameters in the COMPASS divertor in NBI-assisted L-mode plasmas

引用

JOURNAL OF INSTRUMENTATION 2021年第9期16卷

作者： Dimitrova, M. Popov, Tsv. K. Havlicek, J. Bogar, K. Varju, J. Hasan, E. Dejarnac, R. Stockel, J. Imrisek, M. Hron, M. Panek, R. Czech Acad Sci Inst Plasma Phys Slovankou 3 Prague 18200 8 Czech Republic Bulgarian Acad Sci Emil Djakov Inst Elect 72 Tsarigradsko Chaussee Blvd Sofia 1784 Bulgaria St Kliment Ohridski Univ Sofia Sci Res Dept NIS 8 Dragan Tsankov Blvd Sofia 1164 Bulgaria Charles Univ Prague Fac Math & Phys V Holesovickach 2-747 Prague 18000 8 Czech Republic

This paper presents an experimental characterization of the local plasma parameters in the COMPASS open divertor in deuterium, L-mode plasmas by means of Langmuir probes during neutral beam injection (NBI) heating. The effect of NBI heating of the core plasma on the local divertor plasma parameters is investigated under different plasma configurations and different directions of the magnetic field and plasma current for different line-averaged electron densities. At low line-averaged densities below 6 x 10(19) m(-3), a low NBI heating power level does not lead to any significant changes in the plasma parameters in the divertor region. It is also found that for a reversed magnetic field the influence of NBI in the divertor is stronger at higher line-averaged electron density and plasma current. In the divertor, the impact of the NBI heating is more pronounced at high delivered powers (above P-NBI = 320 kW) and line-averaged densities (above 7 x 10(19) m(-3)). The electron temperature and the floating potential at the outer target increases respectively with 10-50% and 100%, while the plasma potential in the inner divertor increases twofold. At a higher line-averaged density, the NBI heating affects the edge plasma, namely, the electron temperature in the midplane scrape-off layer and the heating moves toward the divertor. Thus, a twice as high electron temperature is observed in the divertor and a bi-Maxwellian electron energy distribution function arises.

关键词： Plasma diagnostics - probes data processing methods Ionization and excitation processes

来源：评论

学校读者我要写书评

暂无评论

Avoiding biases in binned fits

引用

JOURNAL OF INSTRUMENTATION 2021年第8期16卷

作者： Gligorov, V. V. Hageboeck, S. Nanut, T. Sciandra, A. Tou, D. Y. Sorbonne Univ LPNHE Paris Diderot Sorbonne Paris Cite CNRSIN2P3 4 Pl Jussieu Paris France CERN 1 Esplanade Particules Meyrin Switzerland Ecole Polytech Fdn Lausanne EPFL Inst Phys Rte Sorge Lausanne Switzerland Univ Calif Santa Cruz Santa Cruz Inst Particle Phys 5 High St Santa Cruz CA 95064 USA

Binned maximum likelihood fits are an attractive option when analysing large datasets, but require care when computing likelihoods of continuous PDFs in bins. For many years the widely used statistical modelling package RooFIT evaluated probabilities at the bin centre, leading to significant biases for strongly curved probability density functions. We demonstrate the biases with real-world examples, and introduce a PDF class to RooFIT that removes these biases. The physics and computation performance of this new class are discussed.

关键词： Analysis and statistical methods data processing methods

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：