AirWatch-RD

Collaboration

The EUSO Collaboration, as of today, is made of the following institutions:

- Italy: INFN, IASF/CNR, INAF, INOA, Universities of Firenze, Genova, Roma1, Palermo, Torino and Trieste
- France: 11 institutions including APC (Paris), CdF (Paris), ISN (Grenoble), LAPP (Annecy)
- Japan: 14 institutions, including RIKEN and ICRR-Tokyo.
- Portugal: LIP-Lisboa.
- USA: 6 institutions including Universities of Alabama (Huntsville), California (Berkley), California (UCLA, Los Angeles), Texas (Austin), Vanderbilt and the NASA Marshall.
- Other participations: Researchers from Germany, United Kingdom and Switzerland cooperate with the Collaboration under many aspects. However their participation has not been formalized yet.

National Responsible: Alessandro Petrolini (Ge)

Location of the experiment: International Space Station or satellite

1. Goal of the experiment

The present R&D project is connected to the EUSO (Extreme Universe Space Observatory) experiment, currently under phase A study by ESA for a possible installation on the International Space Station. The experiment goal is the study of the High Energy part (E ô 3·1019 eV) of the Cosmic Radiation, the Ultra High Energy Cosmic Rays (UHECR), by observing from space the Extensive Air Showers (EAS) produced by the interaction of UHECR with the atmosphere. A large mass of atmosphere can be observed from space and an EAS can be detected by observing the atmospheric nitrogen fluorescence light, isotropically produced during the EAS development, as well as the Cherenkov light, diffusely reflected at the Earth.

More on the experiment…

2.

Activities during 2002

In March 2001 ESA approved the phase A for the EUSO experiment, which started in March 2002 and will end in June 2003. During the phase A the consolidation of the experimental apparatus preliminary design, its optimization and the design of the most critical parts, including the space-related issues, is going on. The following activities were carried on in 2002 within the INFN AirWatch-R&D program.

In general:

- The definition of the observational capabilities of the experiment has been refined.
- The feasibility study of the photo-detector has been refined. The most critical items have been studied and preliminary solutions and designs were proposed.
- Theory: study of the propagation of UHECR over cosmological distances: composition studies and changes during the propagation

Simulation and data analysis:

- Development of the hybrid EAS simulator UNISIM: inclusion of the Cherenkov light production and atmospheric transmission.
- Sensitivity analysis to neutrinos showering in the atmosphere.
- Sensitivity analysis to EAS induced by up-going tau neutrinos and related phenomenology.
- Development of the algorithms for the EAS reconstruction.
- Study of the dependence of the angular resolution on the pixel size.
- Realization of the frame-work and structure of the full EUSO simulation program (ESAF).
- Simulation of more than 30.000 EAS including: hybrid EAS simulation technique, LOWTRAN7 atmospheric transport and simulation of the detector response.

Optics:

- S tudy of the optical adapters for the MAPMT.
- Study of the filters for the primary optics.

Characterization and test:

- Measurements of the properties of the MAPMT (in particular dark current and cross talk).
- Measurement of the dependence of the MAPMT response from the photon incidence angle.
- Development of a multi-channel chip for readout of MAPMT in laboratory test setup.

Photo-detector development:

- Preliminary study of the architecture and layout of the Photo-Detector.
- Conceptual study and development of the elementary-cell and modules of the Photo-Detector.
- Realization of a functional prototype of the elementary-cell base-board
- Realization of the preliminary test version of the front-end chip.
- Study of the Power System for the MAPMT: voltage divider optimization.
- Study of the Photo-Detector Power System: preliminary study of the architecture.

Support measurements:

- Backgroung measurements (night-glow) from ballon (BABY 2001) in three bands; effect of the Moon.
- Measurements of the background from Balloon (BABY 2002) trans-Mediterranean flight for measurements on the sea.
- Setup for the diffusely reflected Cherenkov light measurements (ULTRA).

The following activities were carried on in 2002 in the framework of the INFN AirWatch-R&D program:

- Realization of a full functional prototype of the photodetector elementary cell and test. (50%(*))
- Definition of the architecture of the front-end, trigger and data-handling electronics.(80%)
- Preliminary functional design of the front-end chip.(100%)
- Further background measurements and measurements of the diffusely reflected Cherenkov light.(70% (**))
- Realization of a fast simulation of the experimental apparatus.(80%)

(*) The design of the new baseboard, backbone of the elementary cell, was finished. From the functional point of view it should be a version very close to the final one except for the installation of the front-end chip. The baseboards have been produced, components installed and they are ready to be integrated into the elementary-cell. This implies mounting of the MAPMT and potting. This has not been done yet due to some delay in the overall process caused by the necessity to better understand some technological issues, very critical ones for a space application.

(**) The flight BABY2002 was successfully performed (July 2002) with further background measurements separating the three main N2 fluorescence lines. The single photon counting technique was cross-checked with the charge integration measurement technique. Data analysis in progress. The UV-Scope (Catania/Palermo) and ET-Scope (Torino) set-up was completed. This instrumentation is needed for the measurements campaign called ULTRA and devoted to the measurement of the cloud and land albedo, for the Cherenkov light accompanying the EAS. Preliminary measurements for the two parts performed on October 2002.

Milestones 2003

Definition of the Architecture and Layout of the photodetector; functional design. | 31-12-2003
Realization of the front-end chip prototype | 31-12-2003
Finalization of the fast simulation program of the experiment (Physical processes and experimental apparatus). | 31-12-2003
Re-assessment of the observational capabilities of the experiment and optimisation of the project based on the fast simulation. | 31-12-2003
Reflected/diffused Cherenkov light signal measurements (water, soil and clouds). | 31-12-2003

3. INFN contribution to the experiment in terms of manpower and financial support

Manpower: Five INFN groups (CT, FI, GE, TO and TS) including 50 research associates (25.0 FTE) and 4 technicians (2.5 FTE) plus support from the workshops and engineering design departments of the Sezioni INFN involved

Budget for the year 2003: 1.3 % of CSNII total budget

4. Publications in referred journals (in 2002): 2

5. Number of conference talks (in 2002): 17

6. Number of undergraduate and doctoral thesis on the experiment

- Students: 2
- Ph. D. students: 0

7. Leadership roles and primary responsibilities in the experiment

The following researchers, either INFN employees or INFN research associates, have official responsibilities within the Collaboration for the EUSO phase A.

- Livio Scarsi, Principal Investigator (PI);
- Andrea Santangelo, Deputy PI;
- Osvaldo Catalano, Instrument Manager;
- Alessandro Petrolini, deputy Instrument Manager;
- Bruno Sacco, EUSO Steering Committee, representative for Italy;
- Marco Pallavicini, EUSO Steering Committee, deputy representative for Italy;
- Paolo Lipari, deputy chairman Science Objectives Working group;
- Giacomo D'Ali-Staiti, Simulations responsible;
- Sergio Bottai, Simulations deputy responsible;
- Alessandro Petrolini; italian responsible for the photo-detector;
- Marco Pallavicini, Digital Front-End electronics responsible;
- Paolo Musico, Digital Front-End electronics deputy responsible;
- Maria Concetta Maccarone, Scientific data-analysis responsible;
- Teresa Mineo, deputy Scientific data-analysis responsible;
- Osvaldo Catalano, on-board data handling responsible;
- Gregorio Landi, responsible for Power system;
- Piero Vallania, responsible for the measurement of the Earth diffusely reflected Cherenkov light.

8. Innovative instruments

Development of a space-based photo-detector with large dimensions (a few squared meters), a few hundreds of thousands channels, single photon sensitive in the near-UV, double hit resolution of the order of a few tens of ns, relatively small mass (about one ton), low power consumption (below one kW) and compatible with more than three-years operation on the International Space Station.

This includes the development of a binary front-end ASIC for the MAPMT readout, in a suitable radiation-hard technology, with double hit resolution of a few tens of ns and a power consumption of the order of 1 mW per channel.

9. Competing experiments

UHECR are currently studied, and will be studied, by experiments on Earth (e.g. HiRes, AGASA and AUGER). As of now EUSO is the first experiment foreseen to observe from space. The observation from space will complement the observation from the Earth. A space-based NASA experiment (OWL) is foreseen on a longer time-scale. OWL is in fact in the mid-range strategic plan released by NASA in 2000, which puts OWL after 2012. Compared to AUGER the EUSO experiment is optimized for a higher energy range, partially overlapping the AUGER one.

10. International Committee which has reviewed the experiment

The EUSO experiment is an international experiment carried on by a large Collaboration: Italy, France, Portugal, Japan and US.

It was proposed to ESA in January 2000 and it was reviewed by the following ESA Committees: AWG (Astronomy Working Group), FPAG F undamental Physics Advisory Group), SSAC (Space Science Advisory Committee), EUB (European User Board) and SPC (Space Program Committee).

The EUSO project has also been presented to CNES in September 2001. It has been recommended for the last selection phase of CNES. Support to phase A activities comes from IN2P3/CNRS through local scientific committees and through GDR/PHCE in the form of support to EUSO-AUGER mixed activities.

The EUSO US team presented an EUSO proposal within the NASA MIDEX Announcement of Opportunities. The aim of the MIDEX proposal is to support all phases of the EUSO Mission in the period from 2002 to 2009. NASA approved the phase A of EUSO/US which is already completed. The output of the phase A of EUSO/US is being reviewed by NASA. The review part will end in march, when NASA will decide about the passage to phase B of the EUSO/US project.

Japan phase A activities are supported by RIKEN internal funds.