The main goal of the EPI-CONSOLIDER project is the observational study of the physics of the inflationary period of the universe using Cosmic Microwave Background (CMB) data from the QUIJOTE (Q, U, I Joint TEnerife) experiment and the Planck satellite of the European Space Agency (ESA). In order to achieve this goal it is crucial to develop new instrumentation for the QUIJOTE experiment which allows it to extend its present frequency range and increase its sensitivity. Special emphasis will be put in the detection of the primordial gravitational wave background (GWB) produced during that early period of the universe,  with the goal of reducing the uncertainty of the r parameter (related to the amplitude of those waves) in about an order of magnitude with respect to present upper limits. The GWB leaves an unambiguous imprint in the B-mode CMB polarization anisotropies. Its detection will represent a unique confirmation of inflation and will provide the energy scale at which it happened. The energy scales that will be probed are of the order of or larger than those corresponding to the Grand Unified Theories (GUT) of the fundamental interactions, at least 12 orders of magnitude larger than the ones reachable by present accelerators like the Large Hadron Collider (LHC) at CERN. Many models of inflation will be severely constrained/characterized by the data expected from those very sensitive experiments.
Our scientific results will be strongly based on a combination of two leading CMB experiments, the ESA Planck mission and the QUIJOTE experiment. The first one, launched in May 2009, will observe the temperature and polarization in the whole sky allowing us to determine the cosmological parameters with a precision better than 1%. Most of the members of the Consolider team are actively participating in Planck and will be directly involved in the outstanding cosmological achievements expected with this satellite. QUIJOTE is an experiment to measure the  polarization of the CMB whose Phase I, already funded by the Spanish PNAYA and the institutions forming the consortium, consists in a first telescope of 3 m (already constructed) and two instruments which can be exchanged in the focal plane. The first instrument will be multi-channel, providing the frequency coverage between 11 and 19 GHz plus a single detector at 30 GHz. It is in a well advanced state and is expected to start observations of the CMB polarization in a few months. About one year later, the construction of the second instrument carrying 16 detectors at a central frequency of 30 GHz will be finalised and will start observations. In parallel to the observational campaign to be carried out with the Phase I instruments, we propose to develop the instrumentation of the Phase II of the experiment consisting in a second telescope and a new much more sensitive instrument containing 31 polarimeters with detectors at a central frequency of 41 GHz and a bandwidth of 12 GHz. Considered as a whole, QUIJOTE is expected to be leading CMB polarization observations in Europe and one of the world references in the quest for the primordial GWB in the next years.

In addition to QUIJOTE Phase II, we also propose to explore the viability of a future interferometer having hundreds of elements by developing a pathfinder, for which the radiometers of the 30 GHz instrument of QUIJOTE will be reused. The surmounting of the difficulties related to the correlation of hundreds of detectors would allow a strong improvement in sensitivity with respect to direct imaging experiments for which the maximum number of detectors that can be accommodated is constrained by the limited area available at the focal plane. The challenging scientific objectives proposed in this project are strongly based on state of the art technological developments in the area of low noise amplifiers at millimetre wavelengths. The best performance in low noise devices is achieved when InP is used, reaching noise temperatures of about 10 K. However, this technology is exclusively produced in USA foundries and very severe restrictions are imposed by USA authorities to commercialise it abroad. Then it is imperative to develop technologies in Europe which allow us to get access to very low noise amplifiers for astronomical experiments and, as a by-product, for many other commercial and non-commercial applications. The expertise of the groups forming this Consolider project provides a solid ground to achieve this important technological development.

The groups forming this multidisciplinary project team are internationally recognized for their experience in the CMB field, covering all aspects from instrumental development, observational installation and operation, data reduction and analysis and cosmological interpretation. A large fraction of the team has been directly involved in the development of different CMB experiments during the past 20 years, for example the Tenerife experiment, the COSMOSOMAS experiment, the Very Small Array or the Planck satellite. From the technological side, our team is internationally recognized for its experience in the design and development of amplifiers for different commercial and scientific applications, in particular the design and development of the radiometers at 30 and 44 GHz and the Radiometer Electronics Box Assembly of the Planck Low Frequency Instrument. From the cosmological interpretation side, our team is composed by internationally recognized experts in data analysis and cosmological interpretation, including the proposal and characterization of new sources of primordial effects in the CMB observations. The quality of the researchers covering all aspects of the CMB field from instrument technology to cosmological interpretation, together with our involvement in the already launched Planck satellite and the development of the QUIJOTE Phase II polarization experiment provides a unique opportunity to play a leading role in the field during the next years.