- Functional Requirements - Background - Examples of expected Signal Track - An “idea” of angular resolution EUSO-BALLOON DESIGN REVIEW, , CNES TOULOUSE Andrea Santangelo IAAT, Eberhard-Karls Univerität Tübingen Performances of the EUSO- Balloon

Functional requirements R Background imaging The Instrument shall image the UV sky background in the bandwidth used by the JEM-EUSO mission observational technique. The background includes star light, airglow, light from artificial sources. Test of the trigger algorithms, switch between observational modes R Detection of EAS (from the edge of space) The Instrument shall trigger, detect and image EAS with energy above eV that might develop in the field of view. R Technology demonstrator All key components and the relative sub-assembly items should be tested according to the configuration foreseen for the JEM- EUSO mission. This is needed to test the JEM-EUSO detection chain. UPDATE: Test capability of the IR-CAM; Test of laser induced EAS. CDR – Performances of the EUSO-Balloon2

3 Nightglow background: photons/m 2 /ns/sr Sakaki, BABY, NIGHTGLOW, Tatiana increases by ~1.5 with clouds Airglow (~100 km height): photons/m 2 /ns/sr Moon phases (<25%): <100 ph/m 2 /ns/sr From Tatiana Universitetsky Satellite.  and  = large cities ph/m 2 /ns/sr Background measurements with coarse resolution (~200 km FoV) On the night-sky background. Performances of the EUSO-BalloonCDR –

4 Baby vs. Tatiana and the EUSO-Balloon The Baby (Balloon) Experiment had a reduced field of view with respect to Tatiana  stronger contrast, fluctuations Balloon trajectory EUSO-Balloon: a)will have finer resolution at ground (~200m) b) will implement a control on background variations to keep a stable trigger rate (~7 Hz) O.Catalano et al., NIMA 480 (2002) 547 Performances of the EUSO-Balloon

Background simulation An example of background observation 250 photons / m^2 ns sr Uniform distribution Simulated at electronics level The EUSO Simulation and Anlaysis Framework has been used for the simulation Performances of the EUSO-BalloonCDR –

6 Testing switches The logic of switches of EUSO-Balloon will be tested to verify: a)Capability of protecting the detector from bright events b)Measure their light curve and intensity TLEjet Power10 4 W Duration0.4 s Radius40 km Height in atm. Troposphere WITH SWITCHES 250 pC Performances of the EUSO-Balloon

The observation principle of JEM-EUSO Simulation of the light profile observed at the entrance pupil (above) and throught the instrument using the ESAF code duration ~ 50 – 150  s Performances of the EUSO-BalloonCDR –

8 EUSO-BALLOON vs. JEM-EUSO JEM-EUSOEUSO-Balloon Height(km)42040 Diameter(m)2.51 FoV/pix(deg) FoV/PDM(deg)3.812 Signal Ratio117.6 BG Ratio S/  N E thr (eV)3x x10 18 Number of PDM1431 Maximize performance of EUSO-Balloon keeping parameters as close as possible to JEM-EUSO Performances of the EUSO-BalloonCDR –

Balloon Configuration  modified „Alcala Config“, that is modified JEM-EUSO 1. ISS altitude 400 km  40 km 2. New focal surface parametrization 3. New pixel angle map 5. New optical system 6. Changed FOV: 2*30°  12*12° 7. Background estimation ~ 50% of JEM-EUSO Simulations Performances of the EUSO-BalloonCDR –

Example Shower: 1e19 eV, Theta=20° CDR – Performances of the EUSO-Balloon 10

Example Signal Track Proton 1e19 eV Theta= 20° Phi= 135° CDR – Performances of the EUSO-Balloon 11

Example Signal Track Proton 1e18 eV Theta= 30° Phi=120° Proton 1e19 eV Theta= 30° Phi=120° CDR – Performances of the EUSO-Balloon 12

13 phe/GTU Time(GTU) Xpix Ypix Xpix Proton: E = 4·10 18 eV  = 57.5   =  X 0 = 9.3 km Y 0 = 3.1 km phe/GTU Event landing outside the FoV Typical event observable by EUSO-Balloon: other code So called: “Saitama” code CDR –

Angular Resolution Testing mode: „Debug mode“  a priori knoweldhge of the track 14CDR – Performances of the EUSO-Balloon

15 Energy(eV) Integrated N. Events [10 18,E]eV in 10h LEFT PLOT: Trigger efficiency curve for events with impact point inside FoV. RIGHT PLOT: Black, red and blue curves give preliminary results on the performance from a 10 h duration flight for different assumptions of background and cosmic ray flux. 7 Hz/PDM Trigger efficiency (%) Energy(eV) Efficiency=1 & 1.5 x Aug. flux Efficiency=1 & Auger flux EB & A.fl. & =1.4 phe EB & 1.5xA.fl. & =1.4 phe EB & A.fl. & =2.8 phe EUSO-B. & =1.4 phe/pix/GTU EUSO-B. & =2.8 phe/pix/GTU ● 80 Hz fake trig. o 7 Hz fake trig. Trigger Efficiency CDR – Performances of the EUSO-Balloon

Conclusions EUSO-Balloo will IMAGE the UV sky background (star light, airglow, TLEs, artificial lights) in the bandwidth used by the JEMEUSO mission observational technique. All key components and the relative sub-assembly items will be tested according to the configuration foreseen for the JEM-EUSO mission: in particular the trigger scheme and its capability to cope with the variable sky conditions (EXTREMELY IMPORTANT). Simulation studies have been performed: to understand the structure of the expected signal and the effective energy threshold of EUSO-Balloon and its possibility to detect showers. Results confirm the capability of the instrument of detecting primary cosmic rays of energy E>10 18 eV. Due to the low cosmic ray flux the detection of a couple of events will require few days exposure time  therefore the detection of the first air shower from the edge of the space will most probably require more than one flight. CDR – Performances of the EUSO-Balloon 16