We present the design and experimental demonstration of a 16-channel frequency domain multiplexing (FDM) readout for transition-edge sensor (TES) bolometers. This readout system is going to be implemented on the LSPE/SWIPE balloon-borne experiment, whose goal is to detect the polarization of cosmic microwave background (CMB) at large angular scales and whose launch is scheduled for December 2019.
We describe the fabrication process of the Niobium superconducting inductors and the qualification tests performed in our 300 mK cryogenic facility in INFN Pisa of the boomerang shaped PCBs hosting the LC chains and the gradiometric SQUIDs, which are going to be mounted on the back of the SWIPE focal planes. The development of the warm readout electronics is presented, together with the firmware for the generation and readout of the biasing frequency comb.
We present the design and first tests of a prototype readout for the SWIPE instrument onboard the LSPE balloon-borne experiment. LSPE aims at measuring the linear polarization of the Cosmic Microwave Background (CMB) at large angular scales, to find the imprint of inflation on the B-mode CMB polarization. The SWIPE instrument hosts two focal planes hosting 163 TES Au/Mo spiderweb bolometers each, cooled at 0.3 K for the detection of microwave frequencies of 140, 220 and 240 GHz.
To read all the detectors, a 16 channel frequency domain multiplexing readout system has been devised, consisting of LC resonators composed of custom Nb superconducting inductors and commercial SMD capacitors.
A set-up consisting of 14 LC resonators shows that we can accommodate 16 channels in the frequency range between 200 kHz and 1.6 MHz, since the necessary line-widths can be achieved. A preliminary firmware for the generation and read-out of the biasing frequency comb is also discussed.
In this contribution experimental studies on the laser-assisted welding of transparent polymers with diode laser (wavelength 940 nm) are presented to discuss their potential for the fabrication of micro-devices for micro-chemical engineering and life science. Micro-channel devices such as capillary electrophoresis chips, heat exchangers or static mixers for liquids and gases consist of different micro-patterned sheets with structural details in the range of a few μm. In micro-chemical engineering, in general the sheets of micro-devices are made of metals. In our approaches the use of transparent and micro-patterned polymers such as polyvinylidene fluoride (PVDF) is investigated. For the development of micro-devices in life science the use of sheets made of transparent polymers such as polymethylmethacrylate (PMMA) is presented, e.g., in capillary electrophoresis chips. Devices are built up by stacks of micro-patterned sheets which have to be joined. These sheets are patterned by micro-milling, CO2-laser cutting or hot embossing. Laser-assisted polymer welding of transparent and opaque materials is well established. But the welding of only transparent components is still a challenge in micro-system technology, especially if micro-structures are included. For this purpose very thin absorbing layers with a thickness of about 5nm to 20nm are used in order to establish a welding process between transparent and micro-patterned polymers. The strength of the bonding is characterized by tensile tests as function of absorbing layer thickness, temperature, laser scan velocity and laser scan overlap. The topography is investigated with atomic force microscopy and low voltage scanning electron microscopy.