| 1. |
- Gustafsson, U, et al.
(författare)
-
Compact fiber-optic fluorosensor using a continuous-wave violet diode laser and an integrated spectrometer
- 2000
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 71:8, s. 3004-3006
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Tidskriftsartikel (refereegranskat)abstract
- A compact fluorosensor with a fiber-optic measurement probe was developed, employing a continuous-wave violet diode laser as an exciting source and an integrated digital spectrometer for the monitoring of fluorescence signatures. The system has the dimensions 22x13x8 cm(3), and features 5 nm spectral resolution and an excellent detectivity. Results from measurements on vegetation and human premalignant skin lesions are reported, illustrating the potential of the instrument. (C) 2000 American Institute of Physics. [S0034-6748(00)04508-1].
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| 2. |
- Larsson, Jörgen, et al.
(författare)
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Evaluation of laser-irradiated Ar clusters as a source for time-resolved x-ray studies
- 1999
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 70:5, s. 2253-2256
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the absolute average photon flux, the spectral characteristics, and the time structure of x rays emitted from Ar clusters which were irradiated by a 100 fs laser with an intensity of 10(17) W/cm(2). The measured photon flux was 10(7) photons per shot in the K-alpha (at 3 keV) line in a 4 pi sr solid angle. The temporal structure was measured using a streak camera with a 10 ps time resolution. It was found that less than 1% of the photons were emitted within the 10 ps time-response function of the streak camera. The emission profile is roughly exponential with a time constant of 3 ns. (C) 1999 American Institute of Physics. [S0034-6748(99)03605-9].
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| 3. |
- Yakimov, V, et al.
(författare)
-
Electrostatic force-feedback force sensor incorporated in an ultrahigh vacuum force microscope
- 2000
-
Ingår i: Review of Scientific Instruments. - 0034-6748 .- 1089-7623. ; 71:1, s. 133-136
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Tidskriftsartikel (refereegranskat)abstract
- A force sensor based on a fiber-optic interferometric displacement transducer incorporated in an ultrahigh vacuum atomic force microscope is described. The operation of the sensor is based on balancing the tip-sample interfacial force using an electrostatic actuator. The electrodes of the actuator are formed by the grounded W cantilever and the metallized end facet of the optical fiber used by the interferometer. Chemical reduction of Ag by a wet chemical method is used for metal coating of the fiber end. A special masking procedure is used to obtain a window hole in the metal coating at the position of the fiber core to allow for optical beam output. Using a window instead of a semitransparent metal film allows us to save the low-finesse characteristics of the interferometer which facilitates the calibration of cantilever displacement. The performance of the sensor is discussed and exemplified by experimental results from force-separation measurements on the W-Au system in ultrahigh vacuum. (C) 2000 American Institute of Physics. [S0034-6748(00)01401-5].
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| 4. |
- Johansen, K, et al.
(författare)
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Imaging surface plasmon resonance sensor based on multiple wavelengths : Sensitivity considerations
- 2000
-
Ingår i: Review of Scientific Instruments. - 0034-6748 .- 1089-7623. ; 71:9, s. 3530-3538
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Tidskriftsartikel (refereegranskat)abstract
- A new, multiple wavelength surface plasmon resonance apparatus for imaging applications is presented. It can be used for biosensing, e.g., for monitoring of chemical and biological reactions in real time with label-free molecules. A setup with a fixed incident angle in the Kretschmann configuration with gold as the supporting metal is described, both theoretically and experimentally. Simulations of the sensor response based on independently recorded optical (ellipsometric) data of gold show that the sensitivity for three-dimensional recognition layers (bulk) increases with increasing wavelength. For two-dimensional recognition layers (adlayer) maximum sensitivity is obtained within a limited wavelength range. In this situation, the rejection of bulk disturbances, e.g., emanating from temperature variations, decreases, with increasing wavelength. For imaging surface plasmon resonance the spatial resolution decreases with increasing wavelength. Hence, there is always a compromise between spatial resolution, bulk disturbance rejection, and sensitivity. Most importantly, by simultaneously using multiple wavelengths, it is possible to maintain a high sensitivity and accuracy over a large dynamic range. Furthermore, our simulations show that the sensitivity is independent of the refractive index of the prism. (C) 2000 American Institute of Physics. [S0034-6748(00)02909-9].
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| 5. |
- Johansson, M, et al.
(författare)
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An equipment for three-dimensional spatially resolved gas analysis
- 2000
-
Ingår i: Review of Scientific Instruments. - 0034-6748 .- 1089-7623. ; 71:9, s. 3513-3521
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Tidskriftsartikel (refereegranskat)abstract
- The apparatus described is able to measure three-dimensional temperature and partial pressure distributions in gas mixtures with a spatial resolution better than 0.5 mm. The measurements are performed in a well defined laminar gas flow in a duct of rectangular cross section. The gas mixture is sampled locally with a quartz tube orifice leak movable in three dimensions. Mass spectrometry is used for partial pressure measurements. The total pressure in the duct can be regulated in the range 50-760 Torr and the gas temperature can be varied between room temperature and 500 degrees C. The apparatus is primarily designed for studies of the distribution of reactants and products over catalytic surfaces. Because of the well defined gas flow in the duct the partial pressure distributions of reactants and products over the catalytic surface can be calculated with good accuracy. By comparing calculated pressure distributions to measured ones the local reaction rate on the catalytic surface as well as the pressures of reactants and products at the surface can be obtained. As an example it is shown how the hydrogen distribution over a platinum surface exposed to a mixture of hydrogen, oxygen, and argon can be used to calculate the local water formation rate on the platinum surface. (C) 2000 American Institute of Physics. [S0034-6748(00)01409-X].
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| 6. |
- af Klinteberg, C, et al.
(författare)
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Compact medical fluorosensor for minimally invasive tissue characterization
- 2005
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 76:3
-
Tidskriftsartikel (refereegranskat)abstract
- A compact fiber-optic point-measuring fluorosensor fully adapted to clinical studies is described. The system can use two excitation wavelengths, 337 and 405 nm, obtained from a nitrogen laser directly, or after dye laser conversion, respectively. The image intensifier used in the spectrometer can be gated with a variable time delay, allowing also time-resolved spectra to be extracted, with a time resolution of about 4 ns. Moreover, diffusely scattered white light can be spectrally recorded. The system is fully computer controlled enabling short recording times in clinical application, which are illustrated.
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| 7. |
- Aksela, S., et al.
(författare)
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Study of different SX-700 monochromator designs for the undulator beamline (BL51) at MAX-lab
- 1992
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 63:1, s. 1252-1255
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Tidskriftsartikel (refereegranskat)abstract
- Different designs of the SX-700 plane grating monochromator have been investigated for the undulator beamline (51) by using analytical considerations and carrying out ray tracing calculations. The most important modifications of the original design are those where the ellipsoidal focusing mirror has been replaced by a plane elliptical or by a spherical mirror. A significant advantage of the spherical mirror is essentially better figure accuracies (±0.2 arcsec). This is partly compensated by the introduced coma aberration which, however, can be made small with rather long exit arm lengths (5-6 m). If the slope errors of the plane elliptical mirror can be made as small as 0.5 arcsec, the differences in the ultimate resolution are small between the plane elliptical and spherical designs and then the source size is the main factor.
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| 8. |
- Alm, Ove, et al.
(författare)
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A multiple coaxial wire for pressure calibration
- 1974
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 45:4, s. 594-595
-
Tidskriftsartikel (refereegranskat)abstract
- A single wire containing several metals suitable for pressure calibration has been produced by extrusion. Coaxial combinations of Ce-Bi-TI and Ce-Bi-Ba have been prepared by the procedure described.
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| 9. |
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| 10. |
- Álvarez-Asencio, Ruben, et al.
(författare)
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Note : Determination of torsional spring constant of atomic force microscopy cantilevers: Combining normal spring constant and classical beam theory
- 2013
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 84:9
-
Tidskriftsartikel (refereegranskat)abstract
- A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power spectrum is difficult to obtain due to the high resonance frequency and low signal/noise ratio. The applicability is shown to be general and this simple approach can thus be used to obtain torsional constants for any beam shaped cantilever.
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| 11. |
- Amann, Peter, et al.
(författare)
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A high-pressure x-ray photoelectron spectroscopy instrument for studies of industrially relevant catalytic reactions at pressures of several bars
- 2019
-
Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 90:10
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new high-pressure x-ray photoelectron spectroscopy system dedicated to probing catalytic reactions under realistic conditions at pressures of multiple bars. The instrument builds around the novel concept of a "virtual cell" in which a gas flow onto the sample surface creates a localized high-pressure pillow. This allows the instrument to be operated with a low pressure of a few millibar in the main chamber, while simultaneously a local pressure exceeding 1 bar can be supplied at the sample surface. Synchrotron based hard x-ray excitation is used to increase the electron mean free path in the gas region between sample and analyzer while grazing incidence <5 degrees close to total external refection conditions enhances surface sensitivity. The aperture separating the high-pressure region from the differential pumping of the electron spectrometer consists of multiple, evenly spaced, micrometer sized holes matching the footprint of the x-ray beam on the sample. The resulting signal is highly dependent on the sample-to-aperture distance because photoemitted electrons are subject to strong scattering in the gas phase. Therefore, high precision control of the sample-to-aperture distance is crucial. A fully integrated manipulator allows for sample movement with step sizes of 10 nm between 0 and -5 mm with very low vibrational amplitude and also for sample heating up to 500 degrees C under reaction conditions. We demonstrate the performance of this novel instrument with bulk 2p spectra of a copper single crystal at He pressures of up to 2.5 bars and C1s spectra measured in gas mixtures of CO + H-2 at pressures of up to 790 mbar. The capability to detect emitted photoelectrons at several bars opens the prospect for studies of catalytic reactions under industrially relevant operando conditions.
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| 12. |
- Amole, C., et al.
(författare)
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Autoresonant-spectrometric determination of the residual gas composition in the ALPHA experiment apparatus
- 2013
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 84:6, s. 065110-
-
Tidskriftsartikel (refereegranskat)abstract
- Knowledge of the residual gas composition in the ALPHA experiment apparatus is important in our studies of antihydrogen and nonneutral plasmas. A technique based on autoresonant ion extraction from an electrostatic potential well has been developed that enables the study of the vacuum in our trap. Computer simulations allow an interpretation of our measurements and provide the residual gas composition under operating conditions typical of those used in experiments to produce, trap, and study antihydrogen. The methods developed may also be applicable in a range of atomic and molecular trap experiments where Penning-Malmberg traps are used and where access is limited.
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| 13. |
- Andersson, Mats, et al.
(författare)
-
Flexible lock-in detection system based on synchronized computer plug-in boards applied in sensitive gas spectroscopy
- 2007
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 78:11
-
Tidskriftsartikel (refereegranskat)abstract
- We present a flexible and compact, digital, lock-in detection system and its use in high-resolution tunable diode laser spectroscopy. The system involves coherent sampling, and is based on the synchronization of two data acquisition cards running on a single standard computer. A software-controlled arbitrary waveform generator is used for laser modulation, and a four-channel analog/digital board records detector signals. Gas spectroscopy is performed in the wavelength modulation regime. The coherently detected signal is averaged a selected number of times before it is stored or analyzed by software-based, lock-in techniques. Multiple harmonics of the modulation signal 1f, 2f, 3f, 4f, etc. are available in each single data set. The sensitivity is of the order of 10−5, being limited by interference fringes in the measurement setup. The capabilities of the system are demonstrated by measurements of molecular oxygen in ambient air, as well as dispersed gas in scattering materials, such as plants and human tissue.
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| 14. |
- Andersson, M., et al.
(författare)
-
Using optical tweezers for measuring the interaction forces between human bone cells and implant surfaces: System design and force calibration
- 2007
-
Ingår i: Rev Sci Instrum. - : AIP Publishing. ; 78:7
-
Tidskriftsartikel (refereegranskat)abstract
- Optical tweezers were used to study the interaction and attachment of human bone cells to various types of medical implant materials. Ideally, the implant should facilitate cell attachment and promote migration of the progenitor cells in order to decrease the healing time. It is therefore of interest, in a controlled manner, to be able to monitor the cell adhesion process. Results from such studies would help foresee the clinical outcome of integrating medical implants. The interactions between two primary cell culture models, human gingival fibroblasts and bone forming human osteoblast cells, and three different implant materials, glass, titanium, and hydroxyapatite, were studied. A novel type of optical tweezers, which has a newly designed quadrant detector and a powerful 3 W laser was constructed and force calibrated using two different methods: one method in which the stiffness of the optical trap was obtained by monitoring the phase lag between the trap and the moved object when imposing a forced oscillation on the trapped object and another method in which the maximum trapping force was derived from the critical velocity at which the object escapes the trap. Polystyrene beads as well as cells were utilized for the calibrations. This is the first time that cells have been used directly for these types of force calibrations and, hence, direct measurements of forces exerted on cells can be performed, thus avoiding the difficulties often encountered when translating the results obtained from cell measurements to the calibrations obtained with reference materials. This more straightforward approach represents an advantage in comparison to established methods.
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| 15. |
- Andersson, Odd E., et al.
(författare)
-
Low temperature calibration of Manganin pressure gauges
- 1997
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 68:2, s. 1344-1345
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Tidskriftsartikel (refereegranskat)abstract
- High pressures are often measured using the resistance of Manganin wires. However, the pressure coefficient of resistance is known to depend on temperature. We have measured this temperature dependence by comparing the output from a Manganin gauge with that of a well calibrated Zeranin gauge and determined a correction factor which enables us to measure the pressure at any temperature between 150 and 300 K with a temperature dependent error well below 0.5%.
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| 16. |
- Andersson, Peter, 1981-, et al.
(författare)
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Correction for dynamic bias error in transmission measurements of void fraction
- 2012
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 83:12, s. 125110-
-
Tidskriftsartikel (refereegranskat)abstract
- Dynamic bias errors occur in transmission measurements, such as X-ray, gamma, or neutron radiography or tomography. This is observed when the properties of the object are not stationary in time and its average properties are assessed. The nonlinear measurement response to changes in transmission within the time scale of the measurement implies a bias, which can be difficult to correct for. A typical example is the tomographic or radiographic mapping of void content in dynamic two-phase flow systems. In this work, the dynamic bias error is described and a method to make a first-order correction is derived. A prerequisite for this method is variance estimates of the system dynamics, which can be obtained using high-speed, time-resolved data acquisition. However, in the absence of such acquisition, a priori knowledge might be used to substitute the time resolved data. Using synthetic data, a void fraction measurement case study has been simulated to demonstrate the performance of the suggested method. The transmission length of the radiation in the object under study and the type of fluctuation of the void fraction have been varied. Significant decreases in the dynamic bias error were achieved to the expense of marginal decreases in precision.
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| 17. |
- Andersson, Per, et al.
(författare)
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Electrical resistance of Evanohm under pressure
- 1975
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 46:9, s. 1292-1293
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Tidskriftsartikel (refereegranskat)abstract
- The electrical resistance of Evanohm wire has been determined as a function of hydrostatic pressure. A Teflon cell with a novel type of electrical feedthrough was used to contain the fluid medium. The resistance was found to decrease approximately linearly by 0.3% up to 27 kilobar. The remarkably small variation of its resistance with temperature and pressure makes Evanohm a suitable material for strain measurements under pressure.
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| 18. |
- Andersson, Peter, 1981-, et al.
(författare)
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Neutron tomography of axially symmetric objects using 14 MeV neutrons from a portable neutron generator
- 2014
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 85:8, s. 085109-
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Tidskriftsartikel (refereegranskat)abstract
- In nuclear boiling water reactor cores, the distribution of water and steam (void) is essential for both safety and efficiency reasons. In order to enhance predictive capabilities, void distribution assessment is performed in two-phase test-loops under reactor-relevant conditions. This article proposes the novel technique of fast-neutron tomography using a portable deuterium-tritium neutron generator to determine the void distribution in these loops.Fast neutrons have the advantage of high transmission through the metallic structures and pipes typically concealing a thermal-hydraulic test loop, while still being fairly sensitive to the water/void content. However, commercially available fast-neutron generators also have the disadvantage of a relatively low yield and fast-neutron detection also suffers from relatively low detection efficiency. Fortunately, some loops are axially symmetric, a property which can be exploited to reduce the amount of data needed for tomographic measurement, thus limiting the interrogation time needed.In this article, three axially-symmetric test objects depicting a thermal-hydraulic test loop have been examined; steel pipes with outer diameter 24 mm, thickness 1.5 mm and with three different distributions of the plastic material POM inside the pipes. Data recorded with the FANTOM fast-neutron tomography instrument have been used to perform tomographic reconstructions to assess their radial material distribution. Here, a dedicated tomographic algorithm that exploits the symmetry of these objects has been applied, which is described in the paper.Results are demonstrated in 20 rixel (radial pixel) reconstructions of the interior constitution and 2D visualization of the pipe interior is demonstrated. The local POM attenuation coefficients in the rixels were measured with errors (RMS) of 0.025, 0.020 and 0.022 cm-1, solid POM attenuation coefficient. The accuracy and precision is high enough to provide a useful indication on the flow mode, and a visualization of the radial material distribution can be obtained. A benefit of this system is its potential to be mounted at any axial height of a two-phase test section without requirements for pre-fabricated entrances or windows. This could mean a significant increase in flexibility of the void distribution assessment capability at many existing two-phase test loops.
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| 19. |
- Andersson, Per, et al.
(författare)
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Thermal conductivity of solids under pressure by the transient hot wire method
- 1976
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 47:2, s. 205-209
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Tidskriftsartikel (refereegranskat)abstract
- An electronic circuit has been constructed which delivers constant power to a nickel wire also functioning as a resistance thermometer. The temperature increase versus time, t, is linear in ln t, and the coefficient of slope directly yields the thermal conductivity of the medium surrounding the wire. Systematic errors due to finite time, wire length, and lateral extension of the medium and due to plastic deformation of the wire are analyzed. Temperatures are sampled automatically, and the digital data are reduced by means of an on-line desk calculator. The thermal conductivities of AgCl and polytetrafluoroethylene have been measured up to 10 kilobar.
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| 20. |
- Andersson, Patrik U, 1970, et al.
(författare)
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Efficient source for the production of ultradense deuterium D(-1) for laser-induced fusion (ICF)
- 2011
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 82
-
Tidskriftsartikel (refereegranskat)abstract
- A novel source which simplifies the study of ultradense deuterium D(-1) is now described. This means one step further toward deuterium fusion energy production. The source uses internal gas feed and D(-1) can now be studied without time-of-flight spectral overlap from the related dense phase D(1). The main aim here is to understand the material production parameters, and thus a relatively weak laser with focused intensity ≤1012 W cm−2 is employed for analyzing the D(-1) material. The properties of the D(-1) material at the source are studied as a function of laser focus position outside the emitter, deuterium gas feed, laser pulse repetition frequency and laser power, and temperature of the source. These parameters influence the D(-1) cluster size, the ionization mode, and the laser fragmentation patterns.
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| 21. |
- Andersson, Staffan, et al.
(författare)
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Techniques for determining thermal conductivity and heat capacity under hydrostatic pressure
- 1986
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 57:8, s. 1633-1639
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Tidskriftsartikel (refereegranskat)abstract
- The paper describes a method for measuring the pressure dependence of the thermal conductivity and the heat capacity of hard materials and single crystals. Two parallel metal strips are evaporated onto a flat surface of the specimen, one being used as a heater, the other as a resistance thermometer. The appropriate theoretical expression for a specimen in a liquid medium is fitted to the temperature, sampled at constant time intervals. The thermophysical properties of the liquid high‐pressure medium are taken from hot‐wire experiments. The procedure has been thoroughly tested at atmospheric pressure using an MgO crystal and glass as specimens and liquids of different characteristics in lieu of high‐pressure medium. The accuracy attainable was found to be 3% or better, the standard deviation of the measurements being about 0.3%. The potential of the system was demonstrated by measurements on single‐crystal MgO under pressures up to 1 GPa.
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| 22. |
- Andersson, Å, et al.
(författare)
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The new 1.5 GeV storage ring for synchrotron radiation : MAX II
- 1995
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 66:2, s. 1850-1853
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Tidskriftsartikel (refereegranskat)abstract
- The MAX laboratory at Lund University, Sweden, today operates an accelerator system consisting of a 100 MeV racetrack microtron and a 550 MeV storage ring (MAX I). At the moment (July 1994) a new storage ring MAX II is near completion and will start first injections within 2 months. This work gives an overview of the MAX II project including the first beamlines and a description of the accelerator system. MAX II is a 1.5 GeV third generation light source optimized for the VUV and soft-x-ray region. It consists of a ten cell double bend achromat lattice forming the 90 m circumference ring. Injection is done at 500 MeV from the existing storage ring MAX I, and ramping up to full energy will take place in MAX II. The straight sections have a length of 3.2 m and eight sections are free to house insertion devices. At start up the ring will be equipped with one 7.5 T superconducting wiggler and one 1.8 T multipole wiggler. Two more undulators are ordered and under construction. To be able to achieve the project a few shortcuts have been made in the design of the storage ring: (1) Nonzero dispersion is allowed in the straight sections, (2) chromaticity correction is built into the quadrupole magnets, and (3) the length of the straight sections is limited to 3.2 m. The project is progressing on time. Extraction of an electron beam from the MAX I storage ring has been achieved and has successfully been transported into the MAX II building. The MAX II ring is under assembly with most of the sections already mounted. First injection is planned to take place in August 1994.
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| 23. |
- Arnalds, U. B., et al.
(författare)
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A magnetron sputtering system for the preparation of patterned thin films and in situ thin film electrical resistance measurements
- 2007
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 78:10, s. 103901-
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Tidskriftsartikel (refereegranskat)abstract
- We describe a versatile three gun magnetron sputtering system with a custom made sample holder for in situ electrical resistance measurements, both during film growth and ambient changes on film electrical properties. The sample holder allows for the preparation of patterned thin film structures, using up to five different shadow masks without breaking vacuum. We show how the system is used to monitor the electrical resistance of thin metallic films during growth and to study the thermodynamics of hydrogen uptake in metallic thin films. Furthermore, we demonstrate the growth of thin film capacitors, where patterned films are created using shadow masks.
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| 24. |
- Artemiev, A, et al.
(författare)
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X-ray parabolic lenses made from glassy carbon by means of laser
- 2006
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 77:6
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Tidskriftsartikel (refereegranskat)abstract
- Parabolic planar compound refractive lenses (CRLs) made from glassy carbon by means of laser ablation are presented. They have radii of curvatures of 5 and 200 mu m and geometric apertures of 40 and 900 mu m, respectively. The numbers of biconcave elements in the CRLs were 4, 7, and 200. The planar lenses allow formation of a linear focus of length comparable with the depths of their profiles. Usage of two CRLs in a crossed geometry provides formation of two-dimensional focus. The lenses were tested at the European Synchrotron Radiation Facility at the bending magnet beam line BM-5. The minimum experimental size of the focus has been achieved as 1.4 mu m.
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| 25. |
- Assefa, T. A., et al.
(författare)
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The fluctuation–dissipation measurement instrument at the Linac Coherent Light Source
- 2022
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 93
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Tidskriftsartikel (refereegranskat)abstract
- The development of new modes at x-ray free electron lasers has inspired novel methods for studying fluctuations at different energies and timescales. For closely spaced x-ray pulses that can be varied on ultrafast time scales, we have constructed a pair of advanced instruments to conduct studies targeting quantum materials. We first describe a prototype instrument built to test the proof-of-principle of resonant magnetic scattering using ultrafast pulse pairs. This is followed by a description of a new endstation, the so-called fluctuation–dissipation measurement instrument, which was used to carry out studies with a fast area detector. In addition, we describe various types of diagnostics for single-shot contrast measurements, which can be used to normalize data on a pulse-by-pulse basis and calibrate pulse amplitude ratios, both of which are important for the study of fluctuations in materials. Furthermore, we present some new results using the instrument that demonstrates access to higher momentum resolution.
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