MiniGRAIL

GravitationalRadiation Antenna In Leiden

Kamerlingh Onnes Laboratory, Leiden University, The Netherlands

Projects for students

2005

BACHELOR PROJECT (4 months)

Noise characterization of two-stage SQUID amplifiers for gravitational wave detectors.

Introduction The bandwidth and the sensitivity of the detector both depend on the noise level of the SQUID amplifier, which reads out the transducer. In conventional resonant detectors operating below 4K, the noise level was limited by the SQUID room temperature electronics. To avoid this problem, the SQUID output signal can be amplified at low temperature by another SQUID. This is called a 2-stage SQUID configuration (see picture). The following articles can be useful to understand the aim of the project: M.Podt  et al., Two-stage amplifier based on a double relaxation oscillation superconducting quantum interference device, Applied Phys. Lett. 75 (1999) 2316. R. Mezzena et al., Sensitivity enhancement of Quantum Design dc superconducting quantum interference devices in two-stage configuration, Rev. Sci. Instrum. 72 (2001) 3694.
Student project In order to reduce the SQUID noise, improved SQUID designs were made and the new SQUIDs were fabricated. In this project, the student will participate in the noise characterization at 4.2 K of newly designed dc SQUID amplifiers in a two-stage configuration.
	The picture shows a schematic view and a microphoto of one of the new SQUIDs. This one has large cooling fins to reduce the hot-electron effect. Other designs have a more symmetric configuration to reduce the effect of external noise.