The JEM-EUSO instrument

Abstract

n this paper we describe the main characteristics of the JEM-EUSO instrument. The Extreme Universe Space Observatory on the Japanese Experiment Module (JEM-EUSO) of the International Space Station (ISS) will observe Ultra High-Energy Cosmic Rays (UHECR) from space. It will detect UV-light of Extensive Air Showers (EAS) produced by UHECRs traversing the Earth's atmosphere. For each event, the detector will determine the energy, arrival direction and the type of the primary particle. The advantage of a space-borne detector resides in the large field of view, using a target volume of about 10(12) tons of atmosphere, far greater than what is achievable from ground. Another advantage is a nearly uniform sampling of the whole celestial sphere. The corresponding increase in statistics will help to clarify the origin and sources of UHECRs and characterize the environment traversed during their production and propagation. JEM-EUSO is a 1.1 ton refractor telescope using an optics of 2.5 m diameter Fresnel lenses to focus the UV-light from EAS on a focal surface composed of about 5,000 multi-anode photomultipliers, for a total of a parts per thousand integral 3a <...10(5) channels. A multi-layer parallel architecture handles front-end acquisition, selecting and storing valid triggers. Each processing level filters the events with increasingly complex algorithms using FPGAs and DSPs to reject spurious events and reduce the data rate to a value compatible with downlink constraints

Sensitivity of a proposed space-based Cherenkov astrophysical-neutrino telescope

“…1. These two panels show top and side views of a system consisting of six EUSO-type [66] refractor telescopes with the FoV 60…”

“…However, this would possibly require a larger number of telescope modules, because the FoVs of reflector IACTs are typically much more narrow. An advantage of the reflector system is its larger optical throughput (close to 1, compared to 0.5 of the EUSO type optical system [66]). Another advantage is technological: large optical reflectors are easier to produce, deploy, and operate than large multi-lens refractor systems.…”

“…We assume that part of the FoV affected by city lights is excluded from the exposure area as it is done for the space-based UHECR detector JEM-EUSO [66]. Pixels affected by strong city lights will be excluded based on the high background rate above a certain threshold, measured in the "slow mode" of operation of the telescopes (static photos taken at a fixed rate).…”

The First Level Trigger of JEM-EUSO: Concept and tests

“…The telescope is formed by a system of three Fresnel lenses and a focal surface filled with multi anode photomultipliers read by a frontend electronics based on the single photon counting [2]. The Focal Surface (FS) detector of JEM-EUSO is organized in 137 Photo-Detector Modules (PDM), composed by 9 Elementary Cells (EC) which assemble together 4 Multi-Anode Photomultipliers (MAPMT) of 8 × 8 pixels each.…”

Analysis of EUSO-Balloon data with Offline

“…This can lead to identify structures in the sky map that contain information about the source density and permits to test different models for the acceleration mechanisms. Further details on the JEM-EUSO mission can be found in [2,3]. EUSO-Balloon is a balloon-borne experiment to test technologies and methods that will be used in the JEM-EUSO mission.…”