Physics Procedia最新文献_第10页

Photoluminescence and Low-threshold Nonlinear Optical Properties of SiO2 Nanoparticles 二氧化硅纳米颗粒的光致发光和低阈值非线性光学性质

Physics Procedia Pub Date : 2017-01-01 Epub Date: 2017-02-20 DOI: 10.1016/j.phpro.2017.01.021

A.V. Amosov , V.P. Dzyuba , Yu.N. Kulchin , D.V. Storozhenko

引用次数: 4

Research at the University of Kentucky Accelerator Laboratory 在肯塔基大学加速器实验室进行的研究

Physics Procedia Pub Date : 2017-01-01 Epub Date: 2017-10-26 DOI: 10.1016/j.phpro.2017.09.048

S.F. Hicks , M.A. Kovash

{"title":"Research at the University of Kentucky Accelerator Laboratory","authors":"S.F. Hicks , M.A. Kovash","doi":"10.1016/j.phpro.2017.09.048","DOIUrl":"10.1016/j.phpro.2017.09.048","url":null,"abstract":"<div><p>The Department of Physics and Astronomy at the University of Kentucky operates a 7-MV CN Van de Graaff accelerator that produces primary beams of protons, deuterons, and helium ions. An in-terminal pulsing and bunching system operates at 1.875MHz and is capable of providing 1ns beam bunches at an average current of several microamperes. Nearly all ongoing research programs involve secondary pulsed neutrons produced with gas cells containing deuterium or tritium, as well as with a variety of solid targets. Most experiments are performed at a target station positioned over a deep pit, so as to reduce the background created by backscattered neutrons. Recent experiments will be described; these include: measurements of <em>n-p</em> scattering total cross sections from <em>E</em><sub><em>n</em></sub> <em>=</em> 90 to 1800 keV to determine the <em>n</em>-<em>p</em> effective range parameter; the response of the plastic scintillator BC-418 below 1 MeV to low-energy recoil protons; <em>n-p</em> radiative capture cross sections important for our understanding of nucleosynthesis approximately 2minutes after the occurrence of the Big Bang; γ-ray spectroscopy following inelastic neutron scattering to study nuclear structure relevant to double-β decay and to understand the role of phonon-coupled excitations in weakly deformed nuclei; and measurements of neutron elastic and inelastic scattering cross sections for nuclei that are important for energy production and for our global understanding of the interaction of neutrons with matter.</p></div>","PeriodicalId":20407,"journal":{"name":"Physics Procedia","volume":"90 ","pages":"Pages 440-447"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.phpro.2017.09.048","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79503328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Acceptance Tests for AMS Radiocarbon Measurements at iThemba LABS, Gauteng, South Africa 在南非豪登省的iThemba实验室进行AMS放射性碳测量的验收测试

Physics Procedia Pub Date : 2017-01-01 Epub Date: 2017-10-26 DOI: 10.1016/j.phpro.2017.09.009

Vela L. Mbele, Simon M. Mullins, Stephan R. Winkler, Stephan Woodborne

{"title":"Acceptance Tests for AMS Radiocarbon Measurements at iThemba LABS, Gauteng, South Africa","authors":"Vela L. Mbele, Simon M. Mullins, Stephan R. Winkler, Stephan Woodborne","doi":"10.1016/j.phpro.2017.09.009","DOIUrl":"10.1016/j.phpro.2017.09.009","url":null,"abstract":"<div><p>The accelerator mass spectrometer was commissioned recently at the iThemba LABS 6 MV tandem accelerator. Improvements in the vacuum system, requiring procurement of cryo-pumps and the reducing the tank pressure of the N<sub>2</sub> + CO<sub>2</sub> insulation gas mixture below the level used for IBA measurements, were necessary. This resulted in the reduction of the nitrogen background and improved the resolution of <sup>14</sup>C from <sup>14</sup>N background in the ionisation chamber. The nitrogen was leaking to the stripping canal because of inadequate sealing. The analysing magnet was scaled to detect C<sup>3+</sup> ions, at 3 MV terminal potential. The first sensible spectra allowed for the pin-pointing of many persistent issues. This resulted in measurements with a precision better than 1 pMC, and current blank levels correspond to 12 half-lives of <sup>14</sup>C or ∼68000 years. The radiocarbon sample preparation laboratory has reached production status. A brief outlook of the work towards the implementation of the measurement and chemical preparation protocols for radionuclides <sup>10</sup>Be and <sup>26</sup>Al is also summarised in the conclusion</p></div>","PeriodicalId":20407,"journal":{"name":"Physics Procedia","volume":"90 ","pages":"Pages 10-16"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.phpro.2017.09.009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87279924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

Time-of-flight Neutron Transmission Imaging of Martensite Transformation in Bent Plates of a Fe-25Ni-0.4C Alloy Fe-25Ni-0.4C合金弯曲板马氏体相变的飞行时间中子透射成像

Physics Procedia Pub Date : 2017-01-01 Epub Date: 2017-06-24 DOI: 10.1016/j.phpro.2017.06.005

Y.H. Su , K. Oikawa , T. Shinohara , T. Kai , K. Hiroi , S. Harjo , T. Kawasaki , W. Gong , S.Y. Zhang , J.D. Parker , H. Hayashida , H. Sato , Y. Kiyanagi , Y. Tomota

引用次数: 3

Study of Strength Characteristics of Steel Specimens after Selective Laser Melting of Powder Materials 17-4PH, 316L, 321 粉末材料17-4PH, 316L, 321选择性激光熔化后钢试样强度特性研究

Physics Procedia Pub Date : 2017-01-01 Epub Date: 2017-09-26 DOI: 10.1016/j.phpro.2017.08.012

Anton Zhukov, Boris Barakhtin, Pavel Kuznetsov

{"title":"Study of Strength Characteristics of Steel Specimens after Selective Laser Melting of Powder Materials 17-4PH, 316L, 321","authors":"Anton Zhukov, Boris Barakhtin, Pavel Kuznetsov","doi":"10.1016/j.phpro.2017.08.012","DOIUrl":"10.1016/j.phpro.2017.08.012","url":null,"abstract":"<div><p>By the method of selective laser melting of powder materials nanostructured stainless steels 17-4PH, 316L, 321 were obtained. In all experiments the recorded hardness increase depending on the construction parameters. Obtained relationship of hardness increase with the carbon ratio, which explained by the chemical composition of the metal in the melting zone. It is suggested that the effect of hardness increase is associated with structural changes as to the formation and dissolution of hardening nanophases. Methods of metallography were performed in structural studies. Traces of interlayer segregation were detected inside the grains as turbulent eddies in the bands of different saturation tone caused by the migration of convective (mass transfer) metal atoms. It was visible signs of crystallization through the grain places the image (dendrite crystals). These facts revealed structural features suggest that the adhesion layers of melted powder was initiated by the colder layers and going mechanism epitaxy by coherently oriented groups of atoms from layers of melting.</p></div>","PeriodicalId":20407,"journal":{"name":"Physics Procedia","volume":"89 ","pages":"Pages 179-186"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.phpro.2017.08.012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76025714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 15

Analysis of Spectral Features of Seawaterbiooptical Components Fluorescence from the Excitation-emission Matrix 基于激发-发射矩阵的海水生物光学成分荧光光谱特征分析

Physics Procedia Pub Date : 2017-01-01 Epub Date: 2017-02-20 DOI: 10.1016/j.phpro.2017.01.026

P.A. Salyuk , I.G. Nagorny

引用次数: 0

Editorial Preface 编辑前言

Physics Procedia Pub Date : 2017-01-01 Epub Date: 2017-02-20 DOI: 10.1016/j.phpro.2017.01.001

Roman V. Romashko Professor

引用次数: 0

Light-induced Effects in Sillenite Crystals with Shallow and Deep Traps 具有浅阱和深阱的硅辉石晶体的光致效应

Physics Procedia Pub Date : 2017-01-01 Epub Date: 2017-02-20 DOI: 10.1016/j.phpro.2017.01.029

Tatiana Kornienko , Marina Kisteneva , Stanislav Shandarov , Alexei Tolstik

{"title":"Light-induced Effects in Sillenite Crystals with Shallow and Deep Traps","authors":"Tatiana Kornienko , Marina Kisteneva , Stanislav Shandarov , Alexei Tolstik","doi":"10.1016/j.phpro.2017.01.029","DOIUrl":"10.1016/j.phpro.2017.01.029","url":null,"abstract":"<div><p>This paper presents the light-induced effects in bismuth silicon and bismuth titanium oxide crystals associated both with the electron transitions into the conduction band and with the filling of shallow and deep traps, which determine the optical and electroconductive properties of these crystals. The dynamics of photoconductivity and light-induced absorption is analyzed under conditions of pulsed laser illumination at the wavelength of 532nm. The possibility to describe the relaxation processes of a population for trapping levels with the use of two-exponential function is demonstrated. The photoconductivity dynamics is characterized by two relaxation times on the order of 100ns and 10μs, whereas for light-induced absorption the lifetimes about 10μs and several days for short- and long-lived traps, respectively, have been obtained. Because of this, the relaxation transitions may be occurred both to the shallow trap centers with energy located close to the conduction band and to the deep-lying traps, which should be included into a diversified theoretical model adequately describing the light-induced phenomena in photorefractive sillenite-family crystals.</p></div>","PeriodicalId":20407,"journal":{"name":"Physics Procedia","volume":"86 ","pages":"Pages 105-112"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.phpro.2017.01.029","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75078586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Increased AMS Ion Source Efficiency and Ion Currents by Modifying SNICS Cathode Material and Geometry 通过改进SNICS阴极材料和几何形状，提高AMS离子源效率和离子电流

Physics Procedia Pub Date : 2017-01-01 Epub Date: 2017-10-26 DOI: 10.1016/j.phpro.2017.09.011

Joshua D. Hlavenka, Henry Abrams, Mark L. Roberts, Brett E. Longworth

{"title":"Increased AMS Ion Source Efficiency and Ion Currents by Modifying SNICS Cathode Material and Geometry","authors":"Joshua D. Hlavenka, Henry Abrams, Mark L. Roberts, Brett E. Longworth","doi":"10.1016/j.phpro.2017.09.011","DOIUrl":"10.1016/j.phpro.2017.09.011","url":null,"abstract":"<div><p>A series of tests have been conducted at the Wood Hole Oceanographic Institution's National Ocean Sciences Accelerator Mass Spectrometry facility (NOSAMS) to investigate the effect of sample well geometry and cathode material on C<sup>−</sup> extraction efficiency and beam currents. Ion current production tests were performed on aluminum cathodes that were prepared by drilling sample wells with various diameters (Ø), ranging from 0.50mm to 1.50mm, and depths ranging from 1.3mm to 4.3mm. Cathodes with sample well diameters of 1mm and 0.75mm had marginally better C<sup>−</sup> current, while current for the larger sample wells was lower but more consistent. Depth tests showed an obvious difference in ion beam currents, with shallow wells outperforming the deeper wells. Efficiency tests were first conducted on Al cathodes to find an optimum diameter. Cathodes with Ø of 0.50mm, 0.75mm, and 1.00mm were drilled to a depth of 2.3mm, hand pressed with approximately 250μg of Alfa Aesar graphite, and then run to exhaustion. The best performers were cathodes with Ø of 0.75mm, measuring as much as 16.5% efficiency compared to 13% from the 0.50mm and 15% from the 1.00mm cathodes. Cathodes with Zn inserts were then prepared in the same manner, with a 0.75mm diameter, and showed further improvement, increasing the ion source efficiency to as much as 27%.</p></div>","PeriodicalId":20407,"journal":{"name":"Physics Procedia","volume":"90 ","pages":"Pages 17-21"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.phpro.2017.09.011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76072803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

PEM Water Electrolysis: Preliminary Investigations Using Neutron Radiography 质子交换膜水电解:中子射线照相的初步研究

Physics Procedia Pub Date : 2017-01-01 Epub Date: 2017-06-24 DOI: 10.1016/j.phpro.2017.06.002

Frikkie de Beer , Jan-Hendrik van der Merwe , Dmitri Bessarabov

{"title":"PEM Water Electrolysis: Preliminary Investigations Using Neutron Radiography","authors":"Frikkie de Beer , Jan-Hendrik van der Merwe , Dmitri Bessarabov","doi":"10.1016/j.phpro.2017.06.002","DOIUrl":"10.1016/j.phpro.2017.06.002","url":null,"abstract":"<div><p>The quasi-dynamic water distribution and performance of a proton exchange membrane (PEM) electrolyzer at both a small fuel cell's anode and cathode was observed and quantitatively measured in the in-plane imaging geometry direction(neutron beam parallel to membrane and with channels parallel to the beam) by applying the neutron radiography principle at the neutron imaging facility (NIF) of NIST, Gaithersburg, USA. The test section had 6 parallel channels with an active area of 5 cm<sup>2</sup> and in-situ neutron radiography observation entails the liquid water content along the total length of each of the channels. The acquisition was made with a neutron cMOS-camera system with performance of 10 sec per frame to achieve a relatively good pixel dynamic range and at a pixel resolution of 10 x 10 μm<sup>2</sup>. A relatively high S/N ratio was achieved in the radiographs to observe in quasi real time the water management as well as quantification of water / gas within the channels. The water management has been observed at increased steps (0.2A/cm<sup>2</sup>) of current densities until 2V potential has been achieved. These observations were made at 2 different water flow rates, at 3 temperatures for each flow rate and repeated for both the vertical and horizontal electrolyzer orientation geometries. It is observed that there is water crossover from the anode through the membrane to the cathode. A first order quantification (neutron scattering correction not included) shows that the physical vertical and horizontal orientation of the fuel cell as well as the temperature of the system up to 80°C has no significant influence on the percentage water (∼18%) that crossed over into the cathode. Additionally, a higher water content was observed in the Gas Diffusion Layer at the position of the channels with respect to the lands.</p></div>","PeriodicalId":20407,"journal":{"name":"Physics Procedia","volume":"88 ","pages":"Pages 19-26"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.phpro.2017.06.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75870603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9