Tidsperiod: 2017-01-01 till 2022-12-31

Projektledare: Corey Reed

Finansiär: Vetenskapsrådet

Bidragstyp: Bidrag för anställning eller stipendier

Budget: 12 000 000 SEK

During the 1960's, the first observations were made of ultra high energy (UHE) charged particles arriving from space. These particles, known as cosmic rays, began a pursuit to discover which astronomical objects could accelerate particles to such energies and how they are able to do so. Despite over half a century of investigation, these questions remain open. Neutrino astronomy is poised to provide new discoveries that will yield insight into the origin of cosmic rays and the properties of the objects that accelerate them. Unlike cosmic rays, neutrinos carry no electric charge and interact only via the weak force, and so are not attenuated by matter or magnetic fields.This proposal describes the ARIANNA experiment which will achieve a sensitivity to UHE neutrinos that is an order of magnitude better thanany currently operating neutrino telescope. ARIANNA will consist of a low density array of a large number of radio detection stations located on the Ross Ice Shelf of Antarctica. Each detector station will operate independently in order to measure the strong radio pulse generated when an UHE neutrino collides with the nucleus of an atom in the ice, through the so-called Askaryan effect. The radio clear ice allows ARIANNA to measure neutrinos from up to 1 km away. The ice / water interface below the ice shelf reflects radio pulses, allowing detector stations to be placed at the ice surface while still observing neutrinos arriving from the sky above the telescope.Under this grant, the group at Uppsala University will improve the sensitivity of ARIANNA through the development of new hardware and software technologies as the ARIANNA project expands over the next six years. Experts at Uppsala University will lead the production of a new wind power generation solution that produces little to no radio noise and can survive the extreme Antarctic climate. This work will begin immediately and can improve the sensitivity of the telescope by around 40%.TheÅngström Laboratory, with its large anechoic chamber and radio expertise, will allow the Uppsala group to lead the development of new simulation and analysis software for the ARIANNA project. A focus of the group will be on making an accurate, measurement-based model of the ARIANNA radio antenna. This model will in turn be used by the group, over the next two to three years, to both simulate the detector as well as to reconstruct the properties of a neutrino that generates signals measured by an ARIANNA station. Long term priorities of the group will include the construction and deployment of detector stations and an improved understanding of the ice at the ARIANNA site. Analysis of radio waveform data for signs of neutrino signals will remain a priority each year as the telescope continues to collect data.A pilot array of seven stations has already been constructed at the ARIANNA site. This Hexagonal Radio Array (HRA) has been used to refine the detector design, improve installation methods, study regional ice properties and quantify the radio frequency backgrounds. The HRA has achieved near continuous operation for about 58% of the year, running on solar and battery power. Data from the HRA was used to publish the first search for neutrino signals by the ARIANNA collaboration. The HRA has also observed UHE cosmic rays, which allows the pointing accuracy of the telescope to be assessed.Under this grant, Uppsala University will be one of the mos