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  • 1
    In: Journal of Instrumentation, IOP Publishing, Vol. 17, No. 01 ( 2022-01-01), p. P01013-
    Abstract: The semiconductor tracker (SCT) is one of the tracking systems for charged particles in the ATLAS detector. It consists of 4088 silicon strip sensor modules. During Run 2 (2015–2018) the Large Hadron Collider delivered an integrated luminosity of 156 fb -1 to the ATLAS experiment at a centre-of-mass proton-proton collision energy of 13 TeV. The instantaneous luminosity and pile-up conditions were far in excess of those assumed in the original design of the SCT detector. Due to improvements to the data acquisition system, the SCT operated stably throughout Run 2. It was available for 99.9% of the integrated luminosity and achieved a data-quality efficiency of 99.85%. Detailed studies have been made of the leakage current in SCT modules and the evolution of the full depletion voltage, which are used to study the impact of radiation damage to the modules.
    Type of Medium: Online Resource
    ISSN: 1748-0221
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 2235672-1
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  • 2
    In: Measurement Science and Technology, IOP Publishing, Vol. 34, No. 10 ( 2023-10-01), p. 104003-
    Abstract: Online wall temperatures were measured with fiber-coupled phosphor thermometry in a full-scale gas turbine combustor. The combustor was operated with natural gas and up to 100 vol% hydrogen at engine-relevant conditions. Two phosphors were tested for this application, namely YAG:Dy and YAG:Tm;Li. Although YAG:Tm;Li seemed to be the most promising phosphor for this application, it turned out to be incompatible with the used setup due to a strong interfering signal generated by the laser in the used fiber setup. A strategy to compensate for interferences from flame emissions during natural gas operation was developed. With this strategy it was possible to obtain single-shot temperature measurements at 15 Hz and a precision of 2–7 K for a 1 s average.
    Type of Medium: Online Resource
    ISSN: 0957-0233 , 1361-6501
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1362523-8
    detail.hit.zdb_id: 1011901-2
    SSG: 11
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  • 3
    In: Japanese Journal of Applied Physics, IOP Publishing, Vol. 37, No. 3S ( 1998-03-01), p. 1617-
    Abstract: Polycrystalline CuGaSe 2 thin films have been prepared onto glass by a chemical vapor deposition (CVD) method which uses iodine as the transport agent. The source material was a polycrystalline CuGaSe 2 powder which was pressed into pellets. Single phase CuGaSe 2 films were prepared in a temperature range from 460°C to 560°C and had grain sizes between 0.5 and 5 µm. Thermochemical calculations were performed for the system under equilibrium conditions to model the deposition process. The necessary values for the heat of formation H 298 and the standard entropy S 298 for CuGaSe 2 were estimated to be H 298 =-251 kJ/mol and S 298 =155 J/K mol. The calculations are in good agreement with the experimental observations.
    Type of Medium: Online Resource
    ISSN: 0021-4922 , 1347-4065
    RVK:
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    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 1998
    detail.hit.zdb_id: 218223-3
    detail.hit.zdb_id: 797294-5
    detail.hit.zdb_id: 2006801-3
    detail.hit.zdb_id: 797295-7
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  • 4
    In: Plasma Sources Science and Technology, IOP Publishing, Vol. 30, No. 4 ( 2021-04-01), p. 04LT04-
    Abstract: Plasma-related studies in gas phase are challenging to carry out due to plasma’s transient and unpredictable behavior, excessive luminosity emission, 3D complexity and aggressive chemistry and physiochemical interactions that are easily affected by external probing. Laser-induced fluorescence is a robust technique for non-intrusive investigations of plasma-produced species. In this letter, we present 3D distributions of ground state hydroxyl radicals (OH) radicals in the vicinity of a glow-type gliding arc plasma. Such radical distributions are captured instantaneously in one single camera acquisition by combining structured laser illumination and a lock-in based imaging analysis method called FRAME. The interference of plasma emission is automatically subtracted by the FRAME technique. In addition, the orientation of the plasma discharge can be reconstructed from the 3D data matrix, which can then be used to calculate 2D distributions of ground state OH radicals in a plane perpendicular to the orientation of the plasma channel. Our results indicate that OH distributions around a gliding arc are strongly affected by gas dynamics. We believe that the ability to instantaneously capture 3D transient molecular distributions in a plasma discharge, with minimal plasma emission interference, will have a strong impact on the plasma community for in situ investigations of plasma-induced chemistry and physics.
    Type of Medium: Online Resource
    ISSN: 0963-0252 , 1361-6595
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 2004012-X
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  • 5
    Online Resource
    Online Resource
    IOP Publishing ; 2022
    In:  New Journal of Physics Vol. 24, No. 4 ( 2022-04-01), p. 043026-
    In: New Journal of Physics, IOP Publishing, Vol. 24, No. 4 ( 2022-04-01), p. 043026-
    Abstract: Astronomical imaging can be broadly classified into two types. The first type is amplitude interferometry, which includes conventional optical telescopes and very large baseline interferometry (VLBI). The second type is intensity interferometry, which relies on Hanbury Brown and Twiss-type measurements. At optical frequencies, where direct phase measurements are impossible, amplitude interferometry has an effective numerical aperture that is limited by the distance from which photons can coherently interfere. Intensity interferometry, on the other hand, correlates only photon fluxes and can thus support much larger numerical apertures, but suffers from a reduced signal due to the low average photon number per mode in thermal light. It has hitherto not been clear which method is superior under realistic conditions. Here, we give a comparative analysis of the performance of amplitude and intensity interferometry, and we relate this to the fundamental resolution limit that can be achieved in any physical measurement. Using the benchmark problem of determining the separation between two distant thermal point sources, e.g., two adjacent stars, we give a short tutorial on optimal estimation theory and apply it to stellar interferometry. We find that for very small angular separations the large baseline achievable in intensity interferometry can more than compensate for the reduced signal strength. We also explore options for practical implementations of very large baseline intensity interferometry (VLBII).
    Type of Medium: Online Resource
    ISSN: 1367-2630
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 1464444-7
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  • 6
    Online Resource
    Online Resource
    IOP Publishing ; 2022
    In:  Measurement Science and Technology Vol. 33, No. 12 ( 2022-12-01), p. 127003-
    In: Measurement Science and Technology, IOP Publishing, Vol. 33, No. 12 ( 2022-12-01), p. 127003-
    Abstract: A method is specified which enables lifetime calibration of multiple phosphors and emission lines at the same time to temperatures above 1900 K. The experimental setup and algorithm used for data collection and experimental equipment control are described. The phosphors were coated on an alumina oxide disc and the reference temperature was measured using three type B thermocouples. The algorithm automates the data collection process such that no input from an operator is required during operation. The potential systematic error in calibration temperature was evaluated and was less than 1% around 1400 K.
    Type of Medium: Online Resource
    ISSN: 0957-0233 , 1361-6501
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 1362523-8
    detail.hit.zdb_id: 1011901-2
    SSG: 11
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  • 7
    In: Physics in Medicine & Biology, IOP Publishing, Vol. 68, No. 19 ( 2023-10-07), p. 194001-
    Abstract: Objective. Proton therapy is highly sensitive to range uncertainties due to the nature of the dose deposition of charged particles. To ensure treatment quality, range verification methods can be used to verify that the individual spots in a pencil beam scanning treatment fraction match the treatment plan. This study introduces a novel metric for proton therapy quality control based on uncertainties in range verification of individual spots. Approach. We employ uncertainty-aware deep neural networks to predict the Bragg peak depth in an anthropomorphic phantom based on secondary charged particle detection in a silicon pixel telescope designed for proton computed tomography. The subsequently predicted Bragg peak positions, along with their uncertainties, are compared to the treatment plan, rejecting spots which are predicted to be outside the 95% confidence interval. The such-produced spot rejection rate presents a metric for the quality of the treatment fraction. Main results. The introduced spot rejection rate metric is shown to be well-defined for range predictors with well-calibrated uncertainties. Using this method, treatment errors in the form of lateral shifts can be detected down to 1 mm after around 1400 treated spots with spot intensities of 1 × 10 7 protons. The range verification model used in this metric predicts the Bragg peak depth to a mean absolute error of 1.107 ± 0.015 mm. Significance. Uncertainty-aware machine learning has potential applications in proton therapy quality control. This work presents the foundation for future developments in this area.
    Type of Medium: Online Resource
    ISSN: 0031-9155 , 1361-6560
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1473501-5
    SSG: 12
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  • 8
    Online Resource
    Online Resource
    IOP Publishing ; 2023
    In:  Measurement Science and Technology Vol. 34, No. 6 ( 2023-06-01), p. 064003-
    In: Measurement Science and Technology, IOP Publishing, Vol. 34, No. 6 ( 2023-06-01), p. 064003-
    Abstract: Measuring the temperature below the surface of a thermal barrier coating (TBC) using a thin phosphor layer is challenging primarily due to the absorption and scattering of laser excitation light and phosphor luminescence as they propagate through the coating. One way to increase phosphor luminescence could be to use upconversion phosphor thermometry, which is investigated in the current study. It is attractive because using longer excitation wavelengths reduces the absorption and scattering in TBCs as 8% wt. yttria-stabilize zirconia (8YSZ) generally has lower scattering and absorption coefficients around 1000 nm than at 532 and 355 nm. Therefore, the viability of upconversion to measure the temperature at the bottom of a TBC was evaluated for the first time and was compared with the more conventional downconversion phosphor thermometry. The current work involved an experimental study of several phosphors with lanthanides doped in the 8YSZ host, which were excited through downconversion by pulsed 355 nm and 532 nm laser light and through upconversion with 965 nm laser light. The YSZ:Er,Yb and YSZ:Ho,Yb phosphors show promise for upconversion phosphor thermometry. The experimentally acquired optical phosphor characteristics were used to simulate laser light and phosphor luminescence propagation in TBCs using Kubelka–Munk theory. This was to evaluate the signal strength with upconversion excitation compared to downconversion excitation. Upconversion excitation resulted greater signal strength from an embedded phosphor layer than 532 nm excitation and much higher than 355 nm excitation. Upconversion lifetime phosphor thermometry also resulted in improved phosphor lifetime temperature sensitivity. Coupled with reduced interference from background luminescence from impurities in TBCs with upconversion, it is a promising method for temperature measurements with the thermographic phosphor embedded in or underneath a TBC.
    Type of Medium: Online Resource
    ISSN: 0957-0233 , 1361-6501
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1362523-8
    detail.hit.zdb_id: 1011901-2
    SSG: 11
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  • 9
    In: Biofabrication, IOP Publishing, Vol. 14, No. 4 ( 2022-10-01), p. 045005-
    Abstract: During bioprinting, cells are suspended in a viscous bioink and extruded under pressure through small diameter printing needles. The combination of high pressure and small needle diameter exposes cells to considerable shear stress, which can lead to cell damage and death. Approaches to monitor and control shear stress-induced cell damage are currently not well established. To visualize the effects of printing-induced shear stress on plasma membrane integrity, we add FM 1-43 to the bioink, a styryl dye that becomes fluorescent when bound to lipid membranes, such as the cellular plasma membrane. Upon plasma membrane disruption, the dye enters the cell and also stains intracellular membranes. Extrusion of alginate-suspended NIH/3T3 cells through a 200 µ m printing needle led to an increased FM 1-43 incorporation at high pressure, demonstrating that typical shear stresses during bioprinting can transiently damage the plasma membrane. Cell imaging in a microfluidic channel confirmed that FM 1-43 incorporation is caused by cell strain. Notably, high printing pressure also impaired cell survival in bioprinting experiments. Using cell types of different stiffnesses, we find that shear stress-induced cell strain, FM 1-43 incorporation and cell death were reduced in stiffer compared to softer cell types and demonstrate that cell damage and death correlate with shear stress-induced cell deformation. Importantly, supplementation of the suspension medium with physiological concentrations of CaCl 2 greatly reduced shear stress-induced cell damage and death but not cell deformation. As the sudden influx of calcium ions is known to induce rapid cellular vesicle exocytosis and subsequent actin polymerization in the cell cortex, we hypothesize that calcium supplementation facilitates the rapid resealing of plasma membrane damage sites. We recommend that bioinks should be routinely supplemented with physiological concentrations of calcium ions to reduce shear stress-induced cell damage and death during extrusion bioprinting.
    Type of Medium: Online Resource
    ISSN: 1758-5082 , 1758-5090
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 2500944-8
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  • 10
    In: Journal of Physics: Conference Series, IOP Publishing, Vol. 635, No. 11 ( 2015-09-07), p. 112100-
    Type of Medium: Online Resource
    ISSN: 1742-6588 , 1742-6596
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2015
    detail.hit.zdb_id: 2166409-2
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