We report on the activities preparing long duration stratospheric flights, suitable for CMB (Cosmic Microwave Background) measurements, in the Arctic region. We focus on pathfinder flights, and on two forthcoming experiments to be flown from Longyearbyen (Svalbard islands): the OLIMPO Sunyaev-Zeldovich spectrometer, and the Large-Scale Polarization Explorer (LSPE).

We summarize the results of the Cosmic Microwave Background (CMB) working group of the ARENA project. The focus has been on precision measurements of CMB polarization (looking for the echoes of cosmological inflation) and high angular resolution CMB measurements (looking for Sunyaev Zeldovich effect in distant clusters of Galaxies, to probe the evolution of the Universe, Dark Matter and Dark Energy). For both projects the Dome C site represents the best choice worldwide.

Large millimetric and submillimetric telescopes can play a crucial role in our understanding of the Universe, allowing the direct measurement of early galaxies or the investigation of the earliest stages of star formation. The B modes of CMB polarization are a direct probe of the Inflationary epoch and their measurement promises to provide information on the scale of energies at which the process took place. For these investigations (and many others), large detectors arrays with thousands of pixels are needed, to achieve high mapping speeds. This is especially true in the case of mm and sub/mm observations from extremely cold and dry locations like Dome-C, where ultra-low temperature detectors, reaching photon noise limited performance, are needed to fully exploit the excellent quality of the site. In this paper we present the working principle of the Microwave Kinetic Inductance Detectors and their status of development in Italy, focusing on the key aspects that make them ideal for large arrays of sensors.

Cosmic Microwave Background observations became the tool to probe the the first events of cosmic history. After WMAP data releases, galactic and extragalactic foregrounds are perceived as the main limiting uncertainity for the near-future search for the B-mode polarization inprints from the inflationary era, either through satellites or ground-based experiments like Brain at Dome-C. A combination of technology, scanning strategy and above all, accurate knowledge of polarized foregrounds will be necessary for an optimal mapping of B-mode CMB Polarization. In addition, the search for a better understanding of the galactic foregrounds will provide unprecedented knowledge on the Milky Way structure and star formation.


Future cosmology space missions will concentrate on measuring thepolarization of the Cosmic Microwave Background (CMB), which potentiallycarries invaluable information about the earliest phases of the evolutionof our universe. Such ambitious projects will ultimately be limited bythe sensitivity of the instrument and by the accuracy at whichpolarized foreground emission from our own Galaxy can be subtractedout. We present the PILOT balloon project which will aim atcharacterizing one of these foreground sources, the polarization ofthe dust continuum emission in the diffuse interstellar medium. ThePILOT experiment will also constitute a test-bed for usingmultiplexed bolometer arrays for polarization measurements.


BOOMERanG has recently resolved structures on the last scattering surface at redshift ˜ 1100 with high signal to noise ratio. We review the technical advances which made this possible, and we focus on the current results for maps and power spectra, with special attention to the determination of the total mass-energy density in the Universe and of other cosmological parameters.

In the 1998-99 flight, BOOMERanG has produced maps of ∼4% of the sky at high Galactic latitudes, at frequencies of 90, 150, 240 and 410 GHz, with resolution ≳ 10'. The faint structure of the Cosmic Microwave Background at horizon and sub-horizon scales is evident in these maps. These maps compare well to the maps recently obtained at lower frequencies by the WMAP experiment. Here we compare the amplitude and morphology of the structures observed in the two sets of maps. We also outline the polarization sensitive version of BOOMERanG, which was flown early this year to measure the linear polarization of the microwave sky at 150, 240 and 350 GHz.

In the current cosmological scenario, part of the linearly polarizedemission of the CMB is expected to be rotational (B-modes). Thiscomponent is due to tensor perturbations of the metric produced byprimordial gravitational waves, which are generated a split-second after theBig Bang. The signal expected is of the order of ≲ 0.1 μK, well below the non-rotational component of the polarizationsignal (E-modes), and beyond the sensitivity of present generationinstruments. New, more sensitive instruments are developed inseveral labs, with the goal to measure the B-modes. Control ofsystematics and foregrounds will be the key to make the results ofthese experiments believable. In this paper we shortly outlineBRAIN, a bolometric interferometer devoted to B-modes research,and its pathfinder experiment, devoted to test the Dome-C site.


The BaR-SPOrt experiment is designed to measure theE-mode power spectrum of the Cosmic Microwave BackgroundPolarization (CMBP) in the multipole range 50 < l < 1000. In the current configuration at 32 GHz it can explore up to l = 400.Recent low frequency observations of the target region show that the synchrotron emission should not contamine the CMBP already at 32 GHz. A 6-month observation of a 6° × 6° sky area during the polar night, in idealenvironmental conditions, will allow the Italian-French collaboration to both measure the E–mode power spectrum with appropriate sensitivityand perform important tests of the anomalous dust emission.The BaR-SPOrt 32 GHz instrument, now under test and readyfor operations by Spring 2005, is proposed for 1–2 years Winter operations at Dome C.

The BaR-SPOrt (Balloon-Borne Radiometers for SkyPolarizationObservations) experiment, a program of the AgenziaSpazialeItaliana (ASI) co-funded by PNRA (Progetto Nazionale di Ricerca inAntartide) was originally designed as a payload for long durationballoons flights. The changing scenario, both scientific andstrategic, has led us to propose it for the starting wintercampaign of at the Concordia Base. Here the instrument and thefeatures making it suitable to operate at Dome-C are described.After the initial setup, BaR-SPOrt should not require any kind ofroutine intervention by a dedicated base staff. The experimentwill just need electrical power (less than 2 kW) and a suitableaccommodation on the field. It can be fully monitored andcontrolled, including the data acquisition, through its owntelemetry/telecommand link using IRIDIUM modems. Both the receiverand the critical electronics are housed inside atemperature-controlled vacuum chamber, providing the properlystabilized environment. The cold part of the radiometer employs aclosed loop mechanical cryo-cooler that provides temperatures <70 ± 0.1 K with low power consumption (<200 W).

We show how estimates of parameters characterizing inflation-based theories of structure formation localized over the past year when large scale structure (LSS) information from galaxy and cluster surveys was combined with the rapidly developing cosmic microwave background (CMB) data, especially from the recent Boomerang and Maxima balloon experiments. All current CMB data plus a relatively weak prior probability on the Hubble constant, age and LSS points to little mean curvature (Ωtot = 1.08±0.06) and nearly scale invariant initial fluctuations (ns = 1.03±0.08), both predictions of (non-baroque) inflation theory. We emphasize the role that degeneracy among parameters in the Lpk = 212 ± 7 position of the (first acoustic) peak plays in defining the Ωtot range upon marginalization over other variables. Though the CDM density is in the expected range (Ωcdmh2 = 0.17 ± 0.02), the baryon density Ωbh2 = 0.030 ± 0.005 is somewhat above the independent 0.019 ± 0.002 nucleosynthesis estimates. CMB+LSS gives independent evidence for dark energy (ΩΛ = 0.66 ± 0.06) at the same level as from supernova (SN1) observations, with a phenomenological quintessence equation of state limited by SN1+CMB+LSS to wQ < −0.7 cf. the wQ=−1 cosmological constant case.

The deposition kinetics of InP in MOCVD reactors is presented. The proposed chemical mechanism involves both gas phase and surface reactions. The fundamental hypothesis adopted in deriving the mechanism was a dual site dissociative adsorption of the precursors on the growing surface. In any case, all the rate constants either were taken from the literature or estimated through thermochemical methods. In addition, the deposition reactor was simulated by means of a monodimensional model that accounts for the main reactor features through the boundary layer theory.

In this work, the epitaxial silicon deposition by SiHCl3-hydrogen mixtures in a AMT 7700 barrel reactor was analyzed through a detailed model where a three dimensional flow dynamic was solved by reduction to a two dimensional geometry under cylindrical coordinates. The model was used to investigate the role of the reactor geometry and of the process parameters on the axial deposition uniformity. A comparison with industrial experimental data was also performed.

The study of the anisotropies of the submillimeter relict radiation (RR) can provide important arguments to select among different theoretical scenarios (Panek and Rudak 1988). However, interstellar dust (ISD) emission is present in this spectral region and its patchy distribution can heavily contaminate anisotropy measurements. For example, the most sensitive measurement of CBR anisotropies has been reported so far in a broad band around 1 mm (Melchiorri et al. 1981): the detection of anisotropy is statistically very significant, but its cosmological origin is questionable.

The motion of the earth with respect to the distant matter frame produces a spectral distortion in the observed background radiation given by 1

The second-order approximation in β gives (de Bernardis et al., 1989) 2 where α≅(dlnI/dln v) = (v/I)(dI/dv). The first term in cosθ of equation (2) is the usual dipole anisotropy, the second constant term is the equivalent of the transverse Doppler effect in special relativity, and the third term is the quadrupole anisotropy. It is interesting to note that the quadrupole term is zero in the Rayleigh-Jeans region of the blackbody spectrum: Q ≈ 1/2(3–α)(2–α)β2cos2θ.

We analyze the anisotropies in the extragalactic infrared background and in the source counts in standard cosmology perturbed by large-scale, small-amplitude density fluctuations. The dipole anisotropy of the diffuse background is connected to the dipole of the cosmic background radiation and of the source counts, and a full consistency with a large (≃ 7%) anisotropy in the IRAS source counts is found to imply a low density (Ω0 ≃ 0.2) universe, contrary to a previous claim. We analyze also higher order harmonics. Using the IRAS Low-Resolution All-Sky Maps we obtain an upper limit of 0.17MJy/sr on the dipole of the 100 μm background and show that it is consistent with a source-count anisotropy of 7% only for a low intensity, I ≤ 1.2 M Jy/sr, of the background itself.

We report preliminary results relative to a balloon-borne search for the large-scale anisotropy carried out in 1980 by means of two far infrared photometers centered at 400 and 1100 microns. While these results are consistent with those obtained in an earlier flight, the second, shorter wavelength channel included in the 1980 work provides interesting insights into the influence of galactic dust on such far infrared observations.

Quantum fluctuations of the cosmic background have been measured in the 900 to 2000 micron range (H.P.B.W.) by means of a balloon-borne correlator operating between 5 and 150 Hz. Preliminary results indicate an upper limit √<dP2> ≤ 2.1 × 10−17 watt/(cm2 srad Hz)1/2, corresponding to the noise of a blackbody at a temperature T ≤ 3.1 K at 1σ.