G. Prévôt

POEMMA: Probe Of Extreme Multi-Messenger Astrophysics

The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) mission is being designed to establish charged-particle astronomy with ultra-high energy cosmic rays (UHECRs) and to observe cosmogenic tau neutrinos (CTNs). The study of UHECRs and CTNs from space will yield orders-of-magnitude increase in statistics of observed UHECRs at the highest energies, and the observation of the cosmogenic flux of neutrinos for a range of UHECR models. These observations should solve the long-standing puzzle of the origin of the highest energy particles ever observed, providing a new window onto the most energetic environments and events in the Universe, while studying particle interactions well beyond accelerator energies. The discovery of CTNs will help solve the puzzle of the origin of UHECRs and begin a new field of Astroparticle Physics with the study of neutrino properties at ultra-high energies.

EUSO-Balloon: Observation and Measurement of Tracks from a Laser in a Helicopter

EUSO-Balloon is a prototype detector of the Extreme Universe Space Observatory on the Japanese Experiment Module (JEM-EUSO). EUSO-Balloon was flown successfully as a balloon payload from the Timmins Stratospheric Balloon Launch Facility in Ontario, Canada on 2014 August 24-25 at an altitude of 38 km. To simulate the optical signatures of UV fluorescence photons emitted from cosmic ray air showers generated in the atmosphere, a pulsed UV laser and two UV flashers (LED and Xe) were used. These sources were fired in the instrument field of view for about 2 hours from a helicopter that circled at an altitude of 3 km under the balloon. UV signals were effectively detected, including 270 laser track events. We describe the helicopter laser system and the geometric reconstruction of the laser events that were generated by this system. We report here on the reconstruction of the laser events starting from the information contained in the observed tracks. We note that this work represents the first observation and measurement of aircraft based laser tracks by an optical fluorescence detector flown at near space altitudes.

Performance of the EUSO-Balloon electronics

The 24th of August 2014, the EUSO-BALLOON instrument went for a night flight for several hours, 40 km above Timmins (Canada) balloon launching site, concretizing the hard work of an important part of the JEM-EUSO collaboration started 3 years before. This instrument consists of a telescope made of two lenses and a complex electronic chain divided in two mains sub-systems: the PDM (photo detector module) and the DP (data processing). Each of them is made of several innovative elements developed and tested in a short time. This paper presents their performances before, during and after the flight.

The EUSO@Turlab Project: Results from Phase II

The TurLab facility is a laboratory, equipped with a 5 m diameter and 1 m deep rotating tank,located in the Physics Department of the University of Turin. Originally built mainly to study problems where system rotation plays a key role in the fluid behaviour such as in atmospheric and oceanic flows at different scales, in the past few years the TurLab facility has been used to perform experiments related to observation of Extreme Energy Cosmic Rays from space using the fluo-rescence technique, as in the case of the JEM-EUSO mission, where the diffuse night brightness and artificial light sources can vary significantly in time and space inside the Field of View of the telescope. The description of the EUSO@TurLab project and its first results have been presented in the past. During the last two years many upgrades have been performed on the instrumenta-tion mainly related to the read-out electronics: SPACIROC-1 (employed in EUSO-Balloon and EUSO-TA prototypes) and SPACIROC-3 (EUSO-SPB and Mini-EUSO) which allowed to test a fully equipped Elementary Cell of JEM-EUSO. This phase has been named Phase II. Moreover, the Focal Surface of EUSO-Balloon with the level 1 trigger logic implemented in the Photo-Detector Module has been tested at TurLab after the Canada flight. Finally, tests related to the possibility to employ a EUSO-like detector for other type of applications such as wave monitor- ning and imaging detector have been pursued. The tests and results obtained in EUSO@TurLab Project - Phase II are described.

HVPS system for ∗ – EUSO detectors

In the JEM-EUSO focal instrument four multianode photomultipliers (Elementary Cell unit) are powered by one high voltage generator. The HV control system for Photo Detection Module consists of 9 high voltage generators. HV generators are Cockcroft-Walton voltage multipliers with protection system and with 3 level very fast switches for HV at cathodes. Protection systems were made to protect HVPS itself against possible excess of power consumption, but might be as well used as a protection of PMTs in case of unexpected enlighting. Externally controlled switches can reduce 100 times or 10000 times the PMT collection efficiency to enlarge the PMT dynamics up to factor 10 6 . The HV control unit provides galvanic insulation of HV system, and nallows for input voltage in a range 15-35 V. Control unit provides interface for external voltage setting, control of switches, and emits information about the statuses of 9 HV generators.