Samenvatting

Research is done on the properties of a niobium superconducting magnetic shield sample (see image below this abstract), its magnetic attenuation; and behaviour around the transition temperature 9.25 K. The attenuation of the magnetic shield sample was measured in a cryogenic setup. This is required to verify that the TES bolometers will not measure any magnetic signals as noise when shielded. A new in-field cooling technique was experimentally investigated with measurements during superconductivity phase-transitions. Cooling the shield from a single point could in theory allow the expulsion of a remnant magnetic field.
Previous work on this project showed a deviation in measured and modelled attenuation. Both the measurement and model have been refined during this thesis. They are now in agreement within the significance of the measured data points until a certain depth in the shield sample.
It is known that type II superconductors have a mixed Meissner state at the start of the phase transition. This causes the trapping of a magnetic field inside the superconductor. Measurements using the progression controlled cooling technique showed a reduction of 60~100% for the remnant magnetic field (only in the bottom part of the sample) present during cooling. This was not repeatable for fields of order 10 μT generated by a solenoid.
Concluding that required attenuation of A^(-1)=〖10〗^(-5) in the z-direction has been verified for the shield sample at the supposed detector position. This was measured down to A^(-1)≅〖10〗^(-6) at the lowest measurable depth in this sample. Experimental evidence was found to support the viability of the suggested in-field cooling technique, but only for remnant magnetic fields in the order of ~100 nT.