Second Target Station instruments shine
11 Nov 2009




This year has seen first science being done on Second Target Station instruments. And the instruments are more than living up to expectations!

View of the Polref spin analysing system

Inter science: the first Second Target Station experiment

On 26 May 2009 Inter opened its doors to the first TS-2 users: Jeff Penfold (ISIS), Robert Thomas (Oxford). 

Surfactant and polymer-surfactant mixtures can spontaneously form multilayer structures at interfaces. Such systems are relevant to areas such as soft lubrication, encapsulation, surface delivery and retention, and in understanding bio-lubrication (for example, lung surfactants). This experiment used the power of Inter to explore the kinetics of formation and dissolution of such multilayer structures. A specially designed trough allowed the disassembly of the surface structure to be followed as it progressed in real time.

Inter enabled measurements to be made at time intervals as short as two minutes (with sub-minute measurements predicted for the future). These results demonstrate the ability to follow the kinetics of such processes and open up an exciting new area of science that has been hitherto inaccessible. 


Offspec has successfully demonstrated several of its modes of operation including spin-echo small angle neutron scattering and spin-echo resolved grazing incidence scattering. The complex series of spin manipulation (precession) devices which have been developed at TU Delft are working well and have allowed Offspec to access length scales that were previously unobtainable in traditional reflectometry. Commissioning of the remaining modes is making strong progress alongside the start of the user programme. 

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Nick Webb, Rob Dalgliesh and Richard Coleman (ISIS) with Offspec.
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Polref is now into its commissioning programme.The reflectometer incorporates a polariser guide field and spin analyser for magnetic studies. This will be complemented by the imminent arrival of a three dimensional 2T vector cryomagnet. 

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View of the Polref spin analysing system
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First neutrons were delivered to the Sans2d sample position at the end of March and then on 30 May, to the main detectors in the 13m long, 3.25m diameter vacuum tank. Results are very encouraging and suggest that the increase in flux over the existing Loq instrument is as expected. As a first user experiment, Prof Rob Richardson (Bristol) has studied the temperature dependence of liquid crystalline polymer Bragg peaks. The data demonstrate the extremely wide simultaneous Q range available on Sans2d with the two 1m square detectors.

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View of the two detectors in the Sans2d vacuum tank.
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The Wish instrument opened its shutter for the first time at the end of March, and has run with a liquid methane moderator in the following cycles. Wish has been producing high-quality data from the start, with the doubly-focusing elliptical guide generating the expected high count rate. The detector array on one side of the instrument is fully operational, with the 100,000 pixels, each with 5,000 time bins, generating 1.6 Gb of data per run. Calibration of the detector linear positions is currently underway and is the final milestone before the user program starts. A 14T magnet has been delivered and is soon to be tested on the instrument


a) First diffraction pattern obtained on Wish, from a Si sample with the liquid methane moderator. b) Debye-Scherrer cones on the cylindrical detector array. c) First experiment with a single crystal of BaMnF4 (sample courtesy of Dr . Bombardi, Diamond Light Source).
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LET is a chopper spectrometer with π steradians of detector coverage that is almost gap-free by virtue of using the world’s first 4m long position-sensitive detectors. A complex chopper system involving 7 disks ensures the maximum flux with a clean beam and full control of the energy resolution. LET opened its shutter for neutrons for the first time on the 5 August. Initial measurements show a neutron flux which is close to that predicted by simulations. Results from the detectors are excellent with a 20 mm position resolution. Over the coming months the remaining chopper housings will be put in place and more detectors added.


John Hogg (ALSTEC) working inside the LET vacuum tank. The frames that can be seen on the back will support a wall of 4 m long detectors.
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The Nimrod diffractometer has begun commissioning. Eighteen ZnS scintillator neutron detectors are currently installed at scattering angles 5°-40°, and a low angle bank of 756 detectors cover the angle range 0.5°-2°. Initial results are extremely encouraging, with data being observed which arguably gives Nimrod the widest Q range accessible in a single experiment of any diffractometer in the world.


View of the installed wide angle detectors
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