Expressions of Intent for International Polar Year 2007-2008 Activities

Expression of Interest Details

PROPOSAL INFORMATION

Observations of the Microwave Polarized component of the sky with the BaR-SPOrt experiment  (CMB Polarization with BaR-SPOrt)

Outline
The Cosmic Microwave Background (CMB) radiation, a relic of the Big Bang, is a powerful tool for cosmology investigations. From its anisotropies the precise measurement of global Universe parameters like matter content, matter/energy composition (baryonic, dark matter, and dark energy), and expansion rate, has been allowed. Pioneered by COBE and deepened by WMAP and ground experiments (BOOMERanG, MAXIMA, and DASI, among the others), the study of these anisotropies is expected to be completed with the final WMAP data set and the PLANCK mission. The new frontier is by now the polarized component, which, although detected with the DASI and CBI experiments, is almost unexplored. The related science is of great interest allowing the first feasible way to glance the Inflation era. In fact, the two components of the CMB Polarization (CMBP) – the so-called E- and B-modes – allow the check of important Inflation predictions and the determination of its parameters, thus opening a window to explore the very early stages of the Universe (when the Universe was about 10^(-32) s old). For instance, Inflation predicts that the angular power spectrum of the E-mode is well related to that of the anisotropies: maxima of the E-mode spectrum correspond to minima of the anisotropy one, and reverse. The B-mode even leads to a direct measurement of the amount of gravitational wave background generated by Inflation, providing, in turn, the measurement of the energy density of the Universe when this event occurred. CMBP is thus a tool to study the high energy physics at energy densities far beyond the particle accelerator capabilities. In spite of its importance, its signal is tiny: the E-mode is a few percent of the already faint anisotropy emission, while the B-mode is at least 1 order of magnitude weaker. This requires high sensitivity and stable environmental conditions for its detection. BaR-SPOrt is an experiment aimed at measuring with high precision the power spectrum of the CMBP E-mode: an accurate determination of peak positions and amplitudes will be a fundamental test of the Inflation paradigm. The experiment consists of two instruments operating at 32 and 90 GHz to both measure the CMBP signal and check (and study) the contamination from foreground astrophysical sources (synchrotron and spinning dust emission of the Galaxy). Featured by a 1.8 m telescope, its resolution of 0.4° (0.13°) at 32 (90) GHz matches the angular scales needed for CMBP purposes. High sensitivity and high stability of the observing environment are a must. Polar sites at high altitude provide ideal conditions, especially in the Winter: thermal stability, very low atmospheric emission, and no Sun illumination, make the long integration time required by CMBP possible. The 32 GHz experiment, almost completed, is proposed for ground-based operations from Dome C, where observations c! arried on for 1-2 Antarctica Winters ensure the sensitivity needed for a precise measurement of the E-mode spectrum. Besides observations from Dome-C, the 90 GHz instrument, equipped with a larger number of receivers, can match the needed sensitivity in the shorter time of a Long Duration Balloon (LDB) flight (2-4 weeks). Such long flights are possible only from polar regions, where stable circumpolar wind circulations establish in Summer. In particular, BaR-SPOrt is proposed for an Artic flight with launch from Svalbard islands. The project appears as ID 212 in the ‘List of Ideas Submitted by National Committees or Points of Contact’ of the IPY Framework document.

What significant advance(s) in relation to the IPY themes and targets can be anticipated from this project?
Theme 4: Cosmic microwave background polarization represents the first feasible way to study the Inflation, i.e. the Universe in its very early whiles (about 10^(-32) s after the Big Bang event), and the High Energy Physics at energy densities far beyond the particle accelerators capabilities. Theme 5: The faint signal to be detected requires high stability of environmental conditions and high atmospheric transparency. Winter observations in polar regions at high altitude (e.g. Dome C) allow ideal conditions with high thermal stability, no Sun illumination variations, and low atmosphere emission, for the long time of the Winter night. This makes Dome C the present on-ground site closest to the optimal conditions of space missions. Long duration balloon flights are possible only in polar regions, where the stable circumpolar wind circulation allows flights 2-4 weeks long.

What international collaboration is involved in this project?
BaR-SPOrt is an Italian-French collaboration. The involved institutes are INAF-IASF (PI institute), CNRS-CESR (Toulouse), INAF-IRA (Bologna), CNR-IEIIT (Torino), University of Milano-Bicocca, University of Firenze, University of Roma La Sapienza and CNR-IFAC (Firenze). Scientific collaborations are also active with NIRFI (Nizhnij Novgorod, Russia) and Moscow State University. The experiment is expected to be operated in the frame of the activity of the Italian-French Concordia base at Dome-C.

FIELD ACTIVITY DETAILS

Geographical location(s) for the proposed field activities:
The 32 GHz experiment is expected to be located at the Italian-French Concordia base at Dome-C in Antarctica. The 90 GHz instrument is expected to fly a circumpolar Long Duration Balloon flight. Launch base will be in Svalbard Island (Arctic). The balloon will fly over the ice pack tracing a circular trajectory along a parallel by exploiting the stable circumpolar wind circulation that establishes in Summer.

Approximate timeframe(s) for proposed field activities:
Arctic: 06/2008 -- 07/2008            
Antarctic: 03/2006 -- 09/2007            

Significant facilities will be required for this project:
32 GHz: Dome to locate the 1.8m telescope along with its alt-azimuth mount. 90 GHz: balloon.

Will the project leave a legacy of infrastructure?
The optics/telescope could be available for astrophysics observations at the Dome-C site after the end of the project.

How is it envisaged that the required logistic support will be secured?
Consortium
Own national polar operator
National agency

32 GHz instrument: logistics provided by the Italian-French Dome-C base consortium and/or the two national polar agencies. 90 GHz instrument: flight support by ASI (Italian Space Agency).

Has the project been "endorsed" at a national or international level?
The project is endorsed by INAF ( (Italian) National Institute for Astrophysics), which provides full support of structures and staff to construct and operate the instruments. It has been partially funded by ASI (Italian Space Agency) and PNRA (National Plan for Antarctic Research).

PROJECT MANAGEMENT AND STRUCTURE

Is the project a short-term expansion (over the IPY 2007-2008 timeframe) of an existing plan, programme or initiative or is it a new autonomous proposal?
Expansion

The project has started before the IPY time-frame and the observations are planned to begin one year before (2006). The experiment is part of a wider programme to study the CMBP emission from Dome-C exploiting the unique environmental conditions of the site (thermal stability, no winter Sun illumination, and atmosphere transparency). This includes the proposed experiments BaR-SPOrt, BRAIN/CLOVER, and Milan Polarimeter.

How will the project be organised and managed?
The project is managed by an international collaboration led by the INAF-IASF Bologna Institute. It includes the Institutes/Universities listed in Section 1.7.

What are the initial plans of the project for addressing the education, outreach and communication issues outlined in the Framework document?
Many students have been forming in experimental (design, realization and testing), observing and data analysis (software development) activities; - Development of outreach pages in the web site of the experiment; - Communications through the INAF press office; - Publications of general public articles in magazines.

What are the initial plans of the project to address data management issues (as outlined in the Framework document?
Data are collected and managed in a data server of the collaboration. It is planned that they will be available at the ASDC (ASI Scientific Data Centre), the data centre of the Italian Space Agency. After an initial phase, they will be made available to the scientific community.

How is it proposed to fund the project?
The 32 GHz instrument is funded by ASI and PNRA and is almost completed. INAF (and formerly CNR) provides staff support. The 90 GHz instrument is proposed to ASI.

Is there additional information you wish to provide?
The faint polarization signal, much fainter than the unpolarized background, requires high purity in polarization measurements. The BaR-SPOrt instruments (like that of the ASI-funded space experiment SPOrt) have been developed considering this main aim with many custom devices developed by team members (both design and realization). The resulting performances represent a significant step ahead with respect to the best existing devices and BaR-SPOrt is a fundamental on-the-field test of instrument architectures for future CMBP space missions. BaR-SPOrt is fully remotely controlled to minimize human interventions, an important test for fully remotely controlled instruments to be operated in extreme conditions like a polar night on the Antarctic plateau.

PROPOSER DETAILS

Dr Stefano Cortiglioni
Via Gobetti 101, Bologna


I-40129
Italy

Tel: +39-051-6398703
Mobile: no
Fax: +39-051-6398741
Email:

Other project members and their affiliation