E. Aquilini

MITO: the 2.6 m millimetre telescope at Testa Grigia

Abstract We describe a new ground based telescope dedicated to millimetre cosmological research: MITO, Millimetre and Infrared Testagrigia Observatory. The site and all the instrumental subsystems of the telescope have been chosen to perform high sensitivity measurements for wavelengths ranging from 300 micron to 2 millimetre. The possibility of detecting fluctuations of the Cosmic Microwave Background has been explored for some observational strategies. F. Melchiorri

The BOOMERANG experiment

The BOOMERANG (Balloon Observations Of Millimetric Extragalactic RAdiation aNd Geophysics) experiment is an international effort to measure the Cosmic Microwave Background (CMB) anisotropy on angular scales of 20′ to 4°, with unprecedented sensitivity, sky and spectral coverage. The telescope will be flown from Antarctica by NASA-NSBF with a long duration stratospheric balloon (7–14 days), and is presently scheduled for flight in 1995–1996. The experiment is designed to produce an image of the Cosmic Microwave Background with high sensitivity and large sky coverage. These data will tightly constrain the baryon density, the reionization history, and the formation of large-scale structure in the universe. BOOMERANG will test technologies and return science data that are essential to the design of a future space-borne mission to map CMB anisotropy.

A two-stage 3He-4He fridge for bolometric photometry

Abstract We describe the design, construction and performance of a double stage 3 He– 4 He refrigerator, built to cool down a multiband bolometric photometer at the MITO telescope. The fridge was optimized to work without external pumps, with the main cryostat providing a 4.2 K thermostat at sea level and a 4.0 K one at high mountain pressure conditions. The measured ultimate temperature of the fridge is 290 mK, with a hold time of 81 h. The external heat input on the cold flange is ∼35 μW, with the main bath at 4.0 K. The recycle time is 8 h with a heat input on the thermostat during recycling of ∼6800 J. The cryostat can operate without any relevant changes to performance tilted down to 50° from the vertical position, as needed at the telescope focal plane.

Far infrared multi-frequency observation of interstellar dust clouds

Abstract Diffuse interstellar dust emission at wavelengths between 0.5 and 2 mm has been detected by the ARGO 1993 balloon borne telescope. The instrument scanned the Galactic plane in Aquila and several cirrus clouds in Aries, Taurus and Hercules. The data are spatially consistent with the IRAS 100 μm sky maps, and the spectral behaviour is consistent with a single temperature thennal spectrum with Td ∼ 21 K and a spectral index of emissivity α ∼ 1.5.

Search for Cosmic-Microwave-Background anisotropies at degree angular scales: The ARGO 1993 experiment

SummaryWe describe a balloon-borne telescope, optimized for observations of the Cosmic Microwave Background (CMB) anisotropies in the mm wavelength region, at angular scales around 10. We stress the scientific motivations for these measurements and the problematics driving the experiment design. Using large throughput bolometers cooled at 0.3K we have a sensitivity high enough to detect CMB anisotropies at level ΔT/T∼10−5 in few seconds of integration time.