1. The EUSO-SPB mission
Valentina Scotti
INFN Sezione di Napoli

2. 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

3. 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

4. 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

5. 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

6. 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

7. EUSO-SPB instrument
Optics: 2 Φ1m Fresnel type lenses UV filter ( 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

8. 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)

9. 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

10. 10

11. The first EUSO-SPB flight11
South Pacific Ocean about 200 miles south of Easter Island
South Pacific Ocean about 200 miles south of Easter Island

12. The first EUSO-SPB flight12
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)

13. 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