Journal of Neutron Research最新文献

{"title":"Semi-analytical calculations of intrinsic field magnetic field inhomogeneities for a Neutron Spin Echo spectrometer at the ESS","authors":"A. Kusmin, C. Pappas","doi":"10.3233/jnr-190121","DOIUrl":"https://doi.org/10.3233/jnr-190121","url":null,"abstract":"Neutron Spin Echo methods (NSE) use Larmor labelling to measure the precession phase of the neutron beam polarization around well-defined magnetic fields. Scattering by a sample can affect the resulting precession phase providing information on the sample's structure and dynamics with high accuracy and resolution. A major limitation for the performance of Neutron Spin Echo instruments is the homogeneity of the precession magnetic fields. Here we investigate the influence of the new 'pancake' moderator, which is being built at the European Spallation Source, on the design of a Neutron Spin Echo spectrometer. The calculations show clear gains when the height to width ratios of the rectangular beam cross-sections mimic those of the ESS 'pancake' moderator beams. In such a case the homogeneity of the magnetic field integrals could improve by at least 30%. However, the calculations show that will not be possible to preserve a high resolution and at the same time reduce the length of the instrument. Consequently, NSE spectrometers will perform better at the ESS but they will not be substantially compacter than at other neutron sources e.g. ILL or FRM2.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":"21 1","pages":"167-180"},"PeriodicalIF":1.1,"publicationDate":"2020-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-190121","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48322713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards innovative, successful and cost-efficient use of beam time","authors":"E. Lelièvre-Berna, P. Willendrup","doi":"10.3233/jnr-200147","DOIUrl":"https://doi.org/10.3233/jnr-200147","url":null,"abstract":"This double issue presents some of the work accomplished by two Joint Research Activities (JRAs) of the project World class Science and Innovation with Neutrons in Europe 2020 (SINE2020) financed by the European Commission under the 8th Framework Programme. Within these two JRAs entitled E-tools for Instrumentation and Sample Environment, efforts have been made to explore the full potential of the large scale facilities and enable challenging experiments required by the neutron and muon user communities. In the following pages, we present new McStas components based on Monte-Carlo algorithms to optimise the signal to background ratio, a decisive factor for the success of many experiments. The first McStas bundle allows evaluating one of the major contributions to dose rate around neutron guides. Combined with the next article presenting the investigation of the neutron activation properties of the PE-B4C-concrete recently developed for the European Spallation Source (ESS), this will help facilities to optimise the siting of guides and instruments. The second presented McStas bundle calculates neutron pathways through materials surrounding samples which are generally the most difficult to screen. For the first time, textured materials are considered, taking elastic and inelastic scattering into account, including multiple scattering. The article is followed by a review of different materials for building novel pressure cells for inelastic scattering whose measurements have allowed to determine the effective phonon generalised density of states of these materials, a prerequisite for performing simulations. The next two articles focus on pressure devices. The first one presents the developments of gasket-anvil assemblies for the Paris–Edinburgh cell with 30% improved pressure performance giving a similar signal-to-background ratio. It also describes an improved Bridgman seal package which makes the low-temperature operation of the PE press significantly more reliable. The second article describes a new cell for the investigation of hydrogen storage materials at pressures up to 700 bar and temperatures up to 500°C. The following articles present a simple but very efficient technique for reducing the cool-down times of blue series furnaces by a factor 4 to 5, a comprehensive suite of sample environment equipment for efficient running of muon chemistry experiments over a wide range of conditions, and a portable single-sided NMR setup adapted to a small angle neutron scattering instrument for retrieving both structural and dynamical informations from a single experiment. This issue ends with an article demonstrating that rectangular beam cross-sections with a height over width ratio which mimic the ESS “pancake” moderator beams will lead to an improved homogeneity of the magnetic field integrals of spin echo instruments and an introduction to SECoP, the international Sample Environment Communication Protocol developed on close collaboration with the Int","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2020-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-200147","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43899643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-pressure cell for in situ neutron studies of hydrogen storage materials","authors":"Neslihan Aslan, C. Horstmann, O. Metz, O. Kotlyar, M. Dornheim, C. Pistidda, S. Busch, W. Lohstroh, M. Müller, K. Pranzas","doi":"10.3233/jnr-190116","DOIUrl":"https://doi.org/10.3233/jnr-190116","url":null,"abstract":"","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":"21 1","pages":"125-135"},"PeriodicalIF":1.1,"publicationDate":"2020-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-190116","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46551031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conceptual implementation stages for Moroccan PGAA/NI instruments: STAGE I & II","authors":"H. Amsil, A. Jalil, K. Embarch, H. Bounouira, Abdessamad DIDI, K. Laraki, H. Marah, A. Chetaine","doi":"10.3233/JNR-200171","DOIUrl":"https://doi.org/10.3233/JNR-200171","url":null,"abstract":"The first installation around the tangential beam tube of the Moroccan TRIGA Mark II research reactor comprises combined instruments for Prompt Gamma Neutron Activation Analysis (PGAA) and Neutron Imaging (NI). The implementation of this project is divided over three main stages, namely the installation of the collimator and the primary beam shutter, which is a common section for introduction inside the reactor; the PGAA instruments’ installation; and finally, the installation of the PGNAA/NI combined instruments. The entire design was planned for this project, and detailed information about the first and the second stage is described in this work.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":"1 1","pages":"1-13"},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70093189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neutronics analyses for the conceptual design of the SNS Second Target Station","authors":"I. Remec, F. Gallmeier","doi":"10.3233/jnr-200165","DOIUrl":"https://doi.org/10.3233/jnr-200165","url":null,"abstract":"The Spallation Neutron Source, in operation at the Oak Ridge National Laboratory since 2006, was designed to allow the addition of a second target station and an upgrade of the accelerator proton power. Both upgrades are now underway. This paper describes the evolution of the design of the target of the second target station with the emphasis on the effects of the proton beam footprint on the energy deposition in the target, stresses induced by the pulsed operation, and the importance of the residual heat. The moderator configurations and their optimization are discussed. With the utilization of pure parahydrogen moderators, small neutron beam cross-sections, and the specific optimization, neutron beams of the second target station will achieve exceptionally high peak brightness and time-averaged brightness.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":"22 1","pages":"265-273"},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-200165","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70093166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement of residual strain in tantalum-clad tungsten after hot isostatic pressing","authors":"D. Wilcox, P. Loveridge, S. Kabra, T. Lee, J. Moor, D. Jenkins","doi":"10.3233/jnr-200181","DOIUrl":"https://doi.org/10.3233/jnr-200181","url":null,"abstract":"Tantalum-clad tungsten targets are a popular choice for spallation neutron production, due to the combination of high neutron yield and corrosion resistance. Such targets typically use the Hot Isostatic Press (HIP) process to bond the cladding to the core; this produces a strong bond but also introduces large residual stresses in the target and cladding. This is of particular interest at the ISIS neutron source, because cladding breaches are currently believed to limit the lifetime of ISIS TS2 targets. Two different and complementary methods were used to measure the residual strain in a tantalum-clad tungsten strip manufactured using the same HIP process as ISIS targets. The strip was produced with deliberately asymmetric cladding, causing it to deflect in proportion to the residual stress. FEA simulations were used to back-calculate the stress from the measured deflection. The strip was then placed on the ISIS instrument ENGIN-X, which allowed detailed through-thickness strain profiles to be measured via neutron diffraction. The results of both methods confirm the presence of large residual strains, and agree reasonably well with FEA simulations of the cladding process.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":"22 1","pages":"287-297"},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70093369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat transfer analysis study for the design of the New Polychromatic Beam Neutron Reflectometer CANDOR (Chromatic Analysis Neutron Diffractometer Or Reflectometer).","authors":"Lior Uzan,&nbsp;Juscelino B Leão,&nbsp;Christoph Brocker,&nbsp;Daniel Mattes,&nbsp;Tanya Dax","doi":"10.3233/jnr-200173","DOIUrl":"https://doi.org/10.3233/jnr-200173","url":null,"abstract":"<p><p>A newly developed polychromatic beam neutron reflectometer CANDOR (Chromatic Analysis Neutron Diffractometer Or Reflectometer) on NG-1 at the NIST Center for Neutron research (NCNR) utilizes a wavelength-sensitive neutron detector consisting of 324 analyzing highly-oriented pyrolytic graphite (HOPG) crystals positioned sequentially in rows. Known for having a small thermal diffuse scattering cross section, HOPG crystals can lead to low signal-to-noise ratios in wavelength-sensitive detectors such as CANDOR. Even though it is possible to mathematically separate the desired signal from thermal diffuse scattering; by cooling the detector array of HOPG crystals in order to minimize the Debye Waller effect generates a better solution to this problem. In this heat transfer analysis study we show, within the instrument design constrains and thermodynamic considerations, technical feasibility and test results for the development of the New Polychromatic Beam Neutron Reflectometer CANDOR (Chromatic Analysis Neutron Diffractometer Or Reflectometer) at the NIST Center for Neutron Research.</p>","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":"22 4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-200173","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10022627","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}

{"title":"Assessment of shutdown dose rates at the ESS target cooling system using SCALE6.2","authors":"A. Chambon, E. Klinkby, Leif Emås, B. Lauritzen","doi":"10.3233/jnr-190136","DOIUrl":"https://doi.org/10.3233/jnr-190136","url":null,"abstract":"The production of high-energy neutrons at the European Spallation Source through the spallation process may cause an erosion of the tungsten target. The eroded particles could be released into the target helium cooling system which contains four kind of filters. Among them, the auxiliary filters called “getters” are designed to capture volatile elements and remaining dust. In this work, the ORNL’s SCALE6.2 modelling and simulation suite for nuclear safety analysis is applied to assess shutdown dose rates and determine if added shielding and/or robotic arms are needed for their maintenance. SCALE6.2 is well adapted to treat this problem as it allows for isotope selection regarding source term calculation. Dose rates are determined by an ORIGEN2 source term and a MAVRIC shielding sequence calculation. As SCALE6.2 is non-standard software for ESS, the results are verified against MCNP, which is the baseline tool for neutronics analysis at ESS. Dose rate calculations show that additional shielding and/or robot arm are not needed to remove the getters after 3 months of cooling time, following 5400 h of operation at 5 MW beam power. At a distance of 1 mm from the getter, the dose rate is 0.2 mSv/h in the most conservative estimation.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":"22 1","pages":"309-318"},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-190136","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70092480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-static surfaces in MCNPX: The chopper extension1","authors":"K. Grammer, F. Gallmeier, E. Iverson","doi":"10.3233/jnr-200148","DOIUrl":"https://doi.org/10.3233/jnr-200148","url":null,"abstract":"Rotating objects, such as choppers, are common components of a neutron beamline, and the motion of these components is not described in the static geometry of an MCNPX model. The special case of non-static surfaces for rotation about a stationary point in space has been developed for MCNPX. In addition, velocity dependent kinematics due to the motion of the medium have been implemented. This implementation allows for the simulation of rotating objects at speeds comparable to the velocity of cold neutrons. Applications of the chopper extension will be discussed, including the direct simulation of a bandwidth chopper system, the thermalization of neutrons inside a spinning material, and the discussion of the implementation of a spinning single crystal.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":"22 1","pages":"191-198"},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-200148","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70092807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shielding development for the VENUS imaging instrument","authors":"I. Popova, F. Gallmeier","doi":"10.3233/jnr-200164","DOIUrl":"https://doi.org/10.3233/jnr-200164","url":null,"abstract":"VENUS is an imaging instrument that will use a broad range of neutron wavelengths, from epithermal to cold, will include enhanced contrast mechanisms, and will offer novel energy-selective imaging techniques that directly connect the structures, properties, and function of complex engineering materials and systems to reveal practical and fundamental answers about their real-world performance. The instrument is to be built at SNS beam line 10 and will face the decoupled poisoned hydrogen moderator. The driving cost for the instrument is the beam line and instrument cave shielding. Initial scoping analyses were performed to estimate thickness and composition of shielding materials for the instrument cave and beam line. In light of the upcoming Proton Power Upgrade (PPU) project, these transport analyses were performed for proton beam on target at 1.3 GeV and 2 MW.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":"22 1","pages":"131-138"},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70093462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}