Low temperature devices

LTD-2 Low Temperature Detectors for Neutrinos and Dark Matter II Proceedings of the Second European Workshop on Low Temperature Devices for the Detection of Low Energy Neutrinos and Dark Matter, Annecy-le-Vieux, France, May 2-6, 1988, ed. by L. Gonzales-Mestres and D. Perret-Gallix, Gif-sur-Yvette, France, Editions Frontieres (1988)... 

For routine work at around 0°C on any form of data collection device, a simple low-temperature attachment may be constructed from a copper coil, a refrigerated ethanol bath, a headess air drier, a compressor, and a flexible hose (Marsh and Petsko, 1973). Such an apparatus costs less than 2000 to build and has essentially no operating costs. It fulfllls the most important criterion for a successful low-temperature device that it be so easy to operate as to encourage its use. Its disadvantage is that very low temperatures are not attainable without more sophisticated—and expensive—hardware. 

Stability of protein crystals is often enhanced by maintenance of a constant temperature, regardless of its magnitude. Employment of a low-temperature device eliminates fluctuations in temperature at the crystal due to changes in the room environment. 

Single-crystal x-ray or neutron diffractometers equipped with a low-temperature device were sparse in the 1970s. At present, several tens exist in the world, but very few are capable of handling temperatures below 10 K. As stated in Section III, until now crystal structure studies have been performed only by means of the angle-dispersive method. We discuss below the three main kinds of cryostats that can be used on the instrument geometries described in Section III.B. More details can be found, for example, in Ref. 79, which compares LT setups suitable for accurate electron density map studies. 

Several low-temperature devices have been described for protein crystallography. In the device of Marsh and Petsko [216] a jet of cold dry Nj gas is directed at the crystal. This simple and inexpensive device is good for temperatures around — 4°C. For diffractometers there are a number of devices manufactured commercially [217], which are suitable for very low temperatures. For the oscillation camera, the device of Bartunik and Schubert [233] is recommended. The flow cell is surrounded by a double-walled cylindrical chamber composed of mylar (8 pm thick). A diffuse stream of N2 gas passes through the inner chamber and cools the sample. Icing is prevented... 

Figure 13, A schematic drawing of the low temperature device of Bartunik and Schubert, with the flow cell arrangement. The flow cell is mounted on a standard goniometer head. Cold Nj gas passes through the inner chamber, its temperature is controlled by a sensor and heating coil. Dry circulates through the outer chamber in order to prevent the windows from icing. The walls of the inner and outer parts consist of mylar foils of 8 pm thickness. From Bartunik and Schubert [233].

Increase the operating temperature of the low temperature devices from room temperature to approximately 80°C. 

Albeit these are preliminary, illustrative results, and system optimization is still ongoing, PEGnMg(CI04)2lPN are likely to become an alternative to Li-polymer electrolytes for low-temperature devices, not only in terms of specific cell features,... 

Basically, the results found could also be applied to the design of high-voltage bushings in low temperature devices, especially where limited space is available. 

Molecular Structure Corporation Europe, Unit D2. Chaucer Business Park. Watery Lane. Kem-sing. Sevenoaks, Kent TNI5 6YU, United Kingdom. Imaging plate detectors CCD detectors par-tial-Chi circle low-temperature devices rotating anode generators peripheral devices. 

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