Results from the first missions of the JEM-EUSO program

TL;DR

The JEM-EUSO program has developed and operated multiple detectors in space, balloon, and ground-based platforms, successfully detecting ultra-high energy cosmic rays and UV emissions, paving the way for future space-based UHECR observatories.

Contribution

This paper summarizes the first results from various JEM-EUSO missions, demonstrating the feasibility and initial success of space and balloon detectors for UHECR observation.

Findings

Detection of 9 UHECRs by EUSO-TA coincident with Telescope Array.

Measurement of UV emissions from forests, lakes, and cities by EUSO-Balloon.

Operational validation of subsystems and UV observation capabilities by EUSO-SPB1.

Abstract

The origin of Ultra-High Energy Cosmic Rays (UHECRs) remains unsolved in contemporary astroparticle physics. The objective of the JEM-EUSO program is the realization of a space mission devoted to UHECR physics. Several detectors have been developed in this framework or are under development. EUSO-TA, installed at the Telescope Array site in Utah in 2013, is in operation. It has detected 9 UHECRs in coincidence with Telescope Array fluorescence detector at Black Rock Mesa. EUSO-Balloon flew on board a stratospheric balloon in August 2014. It measured the UV intensity on forests, lakes and cities as well as proved the observation of UHECR-like events reproduced by laser tracks. EUSO-SPB1 was launched on board a super pressure balloon on April 24th 2017 and flew for 12 days. It proved the functionality of all the subsystems of the telescope on a long term and observed the UV emission on oceans. TUS, on board the Lomonosov satellite, in orbit since April 28th 2016, is now included in he JEM-EUSO program and has detected so far in the UHECR trigger-mode a few interesting signals. Mini-EUSO is in its final phase of integration in Russia, and is scheduled for launch on August 22$^{nd}$. The main results obtained so far by these missions are summarized and put in the perspective of future space detectors such as K-EUSO and POEMMA.