Research

Two roads diverged in a wood, and I -

I took the one less traveled by

The road not taken, Robert Frost

1. Development of the cryogenic polarization modulator for the balloon-borne experiment PILOT, for the measurement of interstellar dust polarization at sub-mm wavelengths. Project, construction and tests (mechanics, optical and cryogenic at 4K) of the cryogenic rotator and of its control system. The system enables, autonomously, the rotation of a half wave plate (HWP) at 4K with a reliable control system of the crystal position, with a relative accuracy of about 0°.02.

2. Study of the systematic effects in a typical polarimeter for millimetric wavelengths, for measurements of interstellar dust polarization and of Cosmic Microwave Background polarization (CMB). Modeling of the multiple reflections inside a birefringent crystal, and of the polarized instrumental emissions, modulated at the same frequency of the signal of interest. Cryogenic/optical optimization of a polarimeter for millimetric wavelengths.

3. Development of the mechanical, electric, cryogenic and software setup for electrical and optical tests of bolometers at 300mK in the submillimeter. Use of a cryocompressor and of a bistadium 3He-4He refrigerator for cooling the bolometers down to 300mK. Electrical and optical tests of Cold Electron Bolometers (CEB): load curves, responsivity, noise power spectrum, Noise Equivalent Power (NEP) and study of the sensitivity of the detector to Cosmic Rays (using gamma rays from a ¹³⁷Cs radioactive source and an artificial X-ray source).

4. Study of the Spectral Energy Distribution (SED) of the Carina Nebula from far-infrared to radio wavelengths; data analysis of the satellite and balloon-borne experiments: BOOMERanG 98, WMAP, IRAS, COBE and SPITZER. Modelization of the dust properties (mass, temperature, luminosity, spectral index of emissivity).

5. Simulation of the polarization of the CMB observed through rotating metal mesh HWPs for the balloon-borne experiment LSPE. Study of systematic effects and optimization of the transmission/reflection of the metal mesh HWPs in the millimetric wavelengths (90-200) GHz.

6. Experimental characterization of the thermal gradients of filters (diameter 15 cm) at cryogenic temperatures. Study of the impact of the large radii HWP thermal properties on the observations of the polarization of the Cosmic Microwave Background.

8. Thermo-mechanical design of a polarization modulator for 1.5m HWP and of a focal plane array for future satellite missions. Thermal analysis (static and transient), structural analysis (static and modal).

9. Development, assembly and characterization of the large focal plane TESes array of Advanced ACTPol (AdvACT). Monte Carlo Markov Chain algorithms. New method for setting the optimal bias voltage to be applied to the TESes fed by the same bias line (rebiasing process). Study of the impact, in the estimated TES parameters, from heating of the focal plane. Processing 6-inch diameter Silicon wafers.