Results of the EUSO-SPB1 flight

TL;DR

The EUSO-SPB1 mission, a balloon-borne UV detector for cosmic rays, collected 27 hours of data in 2017, but no cosmic ray tracks were identified, informing future space-based cosmic ray detection efforts.

Contribution

This paper reports the first flight results of the EUSO-SPB1 detector, including data analysis methods and insights for future missions like EUSO-SPB2.

Findings

No cosmic ray candidate tracks were observed.

Data analysis methods successfully identified different event types.

Flight data aligned with simulation predictions.

Abstract

The latest and most advanced effort towards a space-based optical cosmic ray detector developed within the Joint Experiment Mission for the Extreme Universe Space Observatory (JEM-EUSO) collaboration was the Extreme Universe Space Observatory on a Super Pressure Balloon (EUSO-SPB1) mission. The EUSO-SPB1 instrument looks for UV light emitted by extensive air showers above the detectors energy threshold of \unit[3]{EeV}.\\ This detector was launched in 2017 out of Wanaka, New Zealand as a mission of opportunity on a NASA SPB. Over 27 hours of data was taken in air shower detection mode during the 12-day flight over the Pacific Ocean.\\ Besides an overview of the instrument and the mission details, we will show the results of the data analysis of the flight. Methods to search for tracks and other interesting signals were developed and applied to the flight data set revealing different types of events. But no obvious track of a cosmic ray candidate was found. This result is in agreement with a detailed simulation study performed after the flight to include the different conditions. Data of the flown IR camera and weather forecast model were used to determine the cloud conditions within the telescopes FoV. The presented results are also discussed in various separate contributions at this conference. The experience gained during this flight is essential for the preparation of the follow-up mission EUSO-SPB2 which is planned to launch in 2022.