Guide hall n°1, Cold guide H18 | Horizontal scattering geometry, vertical surfaces | Monochromator | Ni/Ti multilayer stack | Wavelength 5 Å | 0.005 Å-1 < q < 1.5 Å-1 | Resolution Δλ/λ = 4% | Polarization option | Fe/Si Multilayer polarizing monochromator | Wavelength 5.5 Å | 0.005 Å-1 < q < 1.5 Å-1 | Resolution Δλ/λ = 4% | Polarizing mirror analyzer for specular reflection | 3He gas cell polarizing analyzer (covering the detector solid angle) for off-specular reflection | Precession coil primary flipper (~100% efficient) | Radio Frequency secondary flipper (~100% efficient) | Flipping ratio of 30 for polarization analysis | Time of Flight | Chopper speed 0-1000 rpm | Chopper separation 4-80 mm | Chopper phase 0-45 deg | 0.002 Å-1 < q < 4 Å-1 | Resolution 0.1-20% (wavelength dependent) | Choppers automatically stopped with windows open for monochromatic modes | Collimation | Slit separation 3.2 m | Maximum slit width 10 mm (this may be increased to full width of 30 mm) | Precision 10 µm | Orientation vertical | Sample position | White beam flux 9.6x109 n/cm2/s | Beam area at sample 10x70 mm | Motors rotation, translation, goniometer and height | Detector | EMBL delay-line type | Max. count rate 300 kHz | Translation 1.1-3.4 m | Rotation -2 to -45 deg. | Size 250x500 mm | Resolution 2.2x3 m2 | Sample Environments | Heater stage < 400oC | Water bath, -10 < T < 80oC | 5 position sample changer | Liquids changer | Humidity chamber | Off-line Langmiur-Blodgett preparation | Quartz window cryomagnet < 2.1 Tesla, 1.5 < T < 300K (can take dilution insert for T > 50 mK) | XYZ coils (B < 0.01 Tesla) and quartz window cryostat, 1.5 < T < 300 K (can also take dilution insert) | Electromagnet, B < 1 Telsa for 15 mm pole separation |
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D17 is the first ILL dedicated reflectometer and it has been designed to be as flexible as possible in resolution and modes of operation. The supermirror-coated guide provides the highest white beam flux at the sample position in the ILL of 9.6x109 n/s/cm2. This flux, combined with the low instrumental background, allows reflectivities down to 10-8 to be measured.
D17 operates in three modes, time-of-flight, monochromatic and polarising. The time-of-flight mode is realised by a double chopper system with variable phase and separation. The useful wavelength range is from 2-20Å; the upper limit set by a frame overlap mirror. The other two modes use multilayer monochromators followed by a composite Ni mirror device to remove long wavelength contamination. Initially the monochromatic and polarising modes will run at a fixed wavelength of 5Å with a base resolution of 4%. Changing between time-of-flight and monochromatic modes of operation takes approximately 15 minutes so users are free to change within a single experiment.
The wide angle multidetector allows the simultaneous measurement of background and off-specular scattering, spanning from 5o at sample-detector distance 3.4m to 13o at 1.1m
When operating in time-of-flight mode, a reflectivity curve over an order of magnitude in scattering vector may be measured without moving the sample or detector. The time-of-flight resolution, due to a double chopper system, is entirely flexible and may be selected to maximise flux, meaning that useful reflectivity curves may be measured in less than a minute. Kinetic measurements, where the sample changes with time, are therefore entirely feasible. This flexibility in resolution is not available at pulsed sources.
D17 has a wide variety of sample environments, however if you cannot find what you require, please contact the instrument team who will be happy to help develop new apparatus in collaboration.
The instrument is suitable for the analysis of surface structures, buried interfaces and in-plane correlations in solids and solid/liquid interfaces. Horizontal surface experiments, such as free liquids, will suffer from a severe restriction in Q-range and flux and are thus not recommended for this instrument. These experiments must be done on the FIGARO reflectometer.
More details in: D17: the new reflectometer at the ILL, R. Cubitt and G. Fragneto, Appl. Phys. A 74 [Suppl.], S329-S331 (2002)
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