The EUSO-SPB mission Valentina Scotti INFN Sezione di Napoli

The Extreme Universe Space Observatory project Observing from space transient luminous phenomena occurring in the Earth's atmosphere Main Objective: Astronomy and Astrophysics through the particle channel Extreme Energy Cosmic Rays: E > 5×1019 eV Identification of EECR sources by high-statistics arrival direction analysis Measurement of the energy spectra of individual sources (spectral shape, flux, power) Understand and constrain acceleration and emission mechanisms

EUSO: the working principle EUSO telescope will observe fluorescence and Cherenkov UV photons generated by Extensive Air Showers created by EECR Main advantages: The target volume is far greater than possible from the ground Full sky coverage First idea: J. Linsley, late ’70s EAS development time ~ 50 – 150 µs

The EUSO program: cosmic rays from space EUSO-TA: ground detector installed in 2014 at Telescope Array site (USA), currently operational EUSO-Balloon: 1st flight from Timmins, (Canada) by the French Space Agency, 2014, technology demonstrator EUSO-SPB: NASA Ultra long duration flight from Wanaka (New Zealand); launched in April 2017 MINI-EUSO: precursor on International Space Station (ISS) approved by Italian and Russian Space agencies; launch in 2017, UV background measurements K-EUSO: bigger telescope on ISS in 2021, equipped with Schmitd optics. It could reach 4 times the exposure of the PAO

Scientific objectives EUSO-Super Pressure Balloon Scientific objectives First fluorescence observations of cosmic ray from above Measure UV background light at night from space Search for faint and ultrafast UV signatures in the atmosphere from other phenomena Establish methods and techniques for a future high energy astroparticle space observatory

EUSO-SPB specifications SPB: when the balloon reaches float altitude, "excess" helium pressurizes the balloon, ballast not required Looks down Operates at night when the moon is down

EUSO-SPB instrument Optics: 2 Φ1m Fresnel type lenses + UV filter (330-400 nm) FoV = ±5.5° Photo Detector Module: array of 36 Multi-Anode PhotoMultiplier Tubes (MAPMTs) of 64 pixels: 2304 channels in total Data Processor: readout performed by one ASIC per MAPMT + multiple trigger levels to filter out noise and identify events of interest + an infrared camera to provide complementary information on the observation conditions + a SiPM Photo Detector in a dedicated box

EUSO-SPB integration and test DP/PDM Integration in Europe Assembly with lenses from Japan in Colorado Field tests in Utah Desert Hang Tests in Texas (NASA) Flight campaign in New Zealand (4 boats)

EUSO-SPB launch 9 Launched from Columbia Scientific Balloon Facility base in Wanaka (NZ) on 24/4/17 at 22:50 South Pacific Ocean about 200 miles south of Easter Island

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The first EUSO-SPB flight 11 South Pacific Ocean about 200 miles south of Easter Island South Pacific Ocean about 200 miles south of Easter Island

The first EUSO-SPB flight 12 ¾ of data downloaded before splash (30 of 40 hours collected) : 60 Gb ~30 hours data w/moon down, dark Data Analysis in progress: searches for UHECR UV Background searches for optical transients in progress searches for man-made flashes (planes, strobe lights) South Pacific Ocean about 200 miles south of Easter Island Clouds moving in the SPB FoV (averages of 1280 GTUs)

Summary 13 an improved telescope prototype was built by the EUSO Collaboration and it met the NASA milestones EUSO-SPB flew on a NASA super pressure balloon mission the upgraded instrument worked properly during all the flight a good amount of data was downloaded to ground data analysis and searches for UHECR are in progress