ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
WEOPMA02
DLS, Oxfordshire, United Kingdom
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
Measurement of the temperature of cryogenically cooled samples in a vacuum environment is a challenging task that requires specialist technical solutions. A new technique enabling non-contact monitoring of temperature has been developed for the I23 beamline. The temperature is determined by measuring the luminescence decay constant of a Bi4Ge3O12 scintillation sensor. One of the main advantages of the non-contact thermometry system is elimination of any connections between the sensor and the readout system that makes it fully compatible with the vacuum environment and necessity of swift replacement and manipulation of the samples. The technique was applied to quantify the thermal performance of different sample mounts that has been used for MX experiment at I23 beamline. It has been shown that the magnitude of the temperature rise across the sample mounts varies in wide range from 60 to 110 K while the temperature of goniometer was 40 K. The obtained results not only explain previous empirical finding but also demonstrated how this technique can aid studies of the complex relationships between various parameters influencing the heat conductance and temperature of the samples.
PSI, Villigen PSI, Switzerland
In spring 2016 a project was started to renew the high-resolution ARPES endstation of the Surface/Interface Spectroscopy (SIS) beamline at PSI. The focus lay on achieving sample temperatures below 4 K while maintaining 6 degrees of freedom. This made it necessary to redesign all thermally active parts, such as the connection to the cryostat, the flexible braid that enables the tilt and azimuthal movement, the sample clamping as well as the thermal isolators that hold the clamping device in place. A newly introduced shield in the main analyser chamber, cooled by separate cryopumps, is used to remove nearly all radiation heat load. A major milestone has recently been taken, by running cryogenic tests on a test stand. The simplified setup reached sample temperatures of 3.35 K. The temperature loss from the cryostat to the sample was as low as 0.6 K. Encouraged by these results, it is believed that the final endstation will be able to reach temperatures even below 3 K. With the new cryo concept, the thermal performance seems to be mainly limited by the radiative heat load emitted by the analyser lens. The new endstation is planned to be in operation by spring 2019.