AUGER

Collaboration

- INFN: Catania, L'Aquila, Milano, Napoli, Pavia, Roma 2 and Torino
- The AUGER project is a large international effort: at present the following countries participate to the project: Argentina, Australia, Bolivia, Brazil, China, Czech Republic, France, Germany, Greece, Italy, Mexico, Poland, Slovenia, United Kingdom and United States.

Laboratory: Malargue (Argentina)

National Responsible: G. Matthiae (Roma2)

1. Goal of the experiment.

The Pierre Auger Observatory is an international scientific project with the objective of studying cosmic rays in the very high energy region, above 1019 eV. The origin and accelerating mechanism of these particles are still unknown.

The two main experiments on high energy cosmic rays which are operational at present, Agasa and HiRes, have produced conflicting data in the region around 1020 eV. It is not clear whether the GZK cut-off due to the interaction of the primaries with the photon cosmic background is at work. The disagreement between the two experiments may be due to a problem of calibration in the energy scale.

Auger is an hybrid system based on the combination of a surface detector (SD) and telescopes of fluorescence detectors (FD). This feature should remove systematic errors on the energy scale.

The rate of cosmic rays with energy around 1020 eV being extremely low, of the order of one per km2 per century, in order to collect a significant statistics, the Auger Observatory is designed to cover a very large area of about 3000 km2.

More on the experiment...

2.

Activities during 2002

The Engineering Array was operated in stable conditions from December 2001 until April 2002 when the fluorescence telescopes were dismantled to allow installation of the new mirror systems.

During these few months of operation we collected about 100 hybrid events, seen simultaneously by the surface and by the fluorescence detectors. The data were analyzed and presented at Conferences.

The Engineering Array is only a small fraction in size (few per cent) of the full Observatory but it includes all elements, surface and fluorescence detectors, calibration systems, communication array and data acquisition.

The success of the operation of the Engineering Array has given confidence on the validity of the choices made on the construction of the detectors. Several minor but relevant modifications have been done with respect to the original design.

The installation of the mirror systems in the two fluorescence detectors buildings of Los Leones and Coihueco has started but with some delay due to the late delivery of some components of the buildings.

The UV filters, camera body and supports were shipped to Malargue and are ready for installation. The other minor components of the cameras are either already made or in advanced state of preparation.

The production of the basis of the PMTs of the FD has started, followed by the production of the PMTs themselves. Full production rate is expected to be reached in March 2003.

A large fraction of the FD analog electronic boards was produced.

The design of the HV and PMT basis of the SD was finalized and the construction is going on according to schedule.

In the field of the analysis the Italian groups are now active on various items. New algorithms have been developed for the reconstruction of the direction and the longitudinal profile of the shower from the FD data.

A considerable amount of work has been devoted to the simulation of events induced by neutrinos. A systematic study has been done on the SD events starting from the experimental threshold in energy.

The following achievements have been obtained:

- Installation and start of the data taking of the final 4 fluorescence telescopes at Los Leones (50 %) (*)
- Installation, commissioning and start of the data taking of the 6 telescopes at Coihueco (postponed to 2003 - delay in buildings delivery)
- Construction of the High Voltage system for 1/4 of the SD (100 %)
- Database of simulated high energy cosmic ray showers (100 %)

(*) installation is in progress despite onsite difficulties

Milestones 2003

Installation of the telescopes in the Los Leones building. | 31-07-2003
Test of the Lidar/Raman system. | 31-07-2003
Installation of the Lidar mirror at the Coihueco building | 31-08-2003
Commissioning of the telescopes at Los Leones | 31-09-2003
Installation of the telescopes in the Coihueco building. | 30-10-2003
Installation and commissioning HV and bases SD detector. | 31-12-2003
Commissioning of the telescopes at Coihueco | 31-12-2003

3. INFN contribution in terms of manpower and financial support.

Manpower: 45 physicists (29.5 FTE), 12 technicians (3.3 FTE).

Budget for the Year 2003: 5.7 % of the CNS2 budget for 2003.

4. Publications on refereed journals (year 2002): 2

5. Conference Talks (year 2002): 4

6. Number of undergraduate and doctoral thesis.

n. 1 PhD

n. 10 Laurea degree

7. Leadership role in the experiment.

- S.Argiro`: task leader of the Data and Processing Analysis
- D.Camin: co-task leader of the Fluorescence Detector Electronics
- R.Cester: member of the Committee referees of the MOUs
- G.Matthiae: member of the AUGER Advisory Board
- P.Privitera: co-task leader of the Fluorescence Detector

8. Innovative instruments.

Current monitor with optoelectronic device to measure the anode current of the PMTs which are run with grounded photocathode (D.Camin, Milano)

Camera Tracer — an event simulator made of a 440 LED matrix controlled by computer to test the camera of the FD (G.Salina, Roma II).

9. Competing experiments.

It is fair to say that there are at present no competing experiments. Present surface arrays and fluorescence telescope systems have acceptance one or two orders of magnitude less than the Auger Observatory.

Competition may arise in the future from experiments with fluorescence telescopes on satellites (Airwatch).

10. International Committe which has reviewd the experiment

The Auger project is a wide international effort. It has been reviewed by several national Committees in all participating Countries (for example by Sagenap in USA).

In addition every few months the Auger management organizes a "Critical Design Review" with participation of distinguished physicists to critically review the progress of the project on its different aspects.