Thesis

Charged Particle Astronomy and Particle physics with the Pierre Auger Observatory

• Call:

  IDPASC Portugal - PHD Programme 2014

• Academic Year:

  2014 /2015

• Domains:

  Experimental Particle Physics | Astroparticle Physics

• Supervisor:

  Lorenzo Cazon

• Co-Supervisor:

  Bernardo Tomé

• Institution:

  Instituto Superior Técnico

• Host Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Abstract:

  The Pierre Auger Observatory aims at identifying the primary composition of cosmic rays and the sources which accelerate them to energies well above the ones achieved at Earth; but also at studying particle physics. At these energies, cosmic rays are not detected directly; the atmosphere acts as a calorimeter and an extensive air shower is produced. The nature and sources of the UHECR have remained in mystery for decades. We still do not know their composition, and the acceleration astrophysical scenarios point to the most violent phenomena in nature, like Active Galactic Nuclei or Gamma Ray Bursts. Nevertheless, within the distances imposed by the interactions of UHECR with the Microwave Background, the amount of possibilities are constrained. The mass composition of the primaries, the energy spectrum and the arrival direction are key to unveil the UHECR secrets. The Observatory is using 1600 water Cerenkov detectors covering an area of 3600 km2 to sample the shower particles when they reach ground. Those detectors measure the energy deposited by charged particles when releasing Cerenkov light in water. In addition to that, an optical telescope picking up ultraviolet light -which is produced by fluorescence of the nitrogen molecules excited by the cascade particles can actually see the longitudinal development of the shower whereas it crosses the atmosphere. Cerenkov light accompanies this emission carrying also valuable information. The light profile imaged by the FD reflects the superposition of gamma showers from neutral pion decay; the time and position of muon detection in the SD gives direct indication of the profile of the decays of charged pions and thus they can open new windows to peer into the secrets of the hadronic interactions in showers, at energies above the ones tested at the LHC. The observatory is also to deploy a series of complementary detectors that include: antennas for radio detection, a second detector acompanying all Cerenkov tanks (yet to be decided the specifics, the so called B2015), a set of buried scintillators (AMIGA), and an engeneering of segmented RPCs beneath the Cerenkov tanks (MARTA engeneering array). The student is expected to identify new ways to extract information from the air showers and relate it to the high energy particle physics actual puzzles, and devise new techniques to measure these information, establishing experimental requirements, and possibly establishing their feasibility. Namely, the muonic information will be specially pursued. Great amounts of enthusiasm and innovative thinking will be very helpful to achieve this goal. The student will be fully involved in the Auger Observatory, which is becoming the main test-bead for UHECR experiments through its multiple enhancements projects.