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Performance aspects of the instrument. M. Bertaina Univ. Torino & INFN. EUSO Balloon Phase A Review Meeting, CNES Toulouse, February 2 nd 2012. Functional Requirements. R-4.1-1 Background imaging
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Performance aspects of the instrument M. Bertaina Univ. Torino & INFN EUSO Balloon Phase A Review Meeting, CNES Toulouse, February 2nd 2012
Functional Requirements • R-4.1-1 Background imaging The Instrument shall image the UV sky background in the bandwidth used by the JEMEUSO mission observational technique. The background includes star light, airglow, light from artificial sources. • R-4.1-2 Detection of EAS The Instrument shall trigger, detect and image EAS with energy above 1018 eV that might develop in the field of view. • R-4.1-3 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 technique. From:EUSO BALLOON INSTRUMENT Technical Specification document Document: EUSO-TS-INST-206-LAL V1.0
On the Sky Background Nightglow background: 100 - 500 photons/m2/ns/sr Sakaki, BABY, NIGHTGLOW, Tatiana increases by ~1.5 with clouds Airglow (~100 km height): 250 - 600 photons/m2/ns/sr Moon phases (<25%): <100 ph/m2/ns/sr Background measurements with coarse resolution (~200 km FoV) From Tatiana Universitetsky Satellite. a and b = large cities ph/m2/ns/sr 2000 1000 500
BABY vs Tatiana: with reduced FoV higher fluctuations are expected • EUSO-Balloon: • will have finer resolution at ground (~200m) • b) will implement a control on background variations to keep a stable trigger rate (~7 Hz) Balloon trajectory O.Catalano et al., NIMA 480 (2002) 547
SWITCHES LOGIC AND BRIGHT EVENTS (TLEs) NO SWITCHES THE SIGNAL HAS BEEN SAMPLED: THE INTERVAL BETWEEN 2 GTUs IS 1 ms!!! 250 pC 0.4 s 0 s WITH SWITCHES • The logic of switches of EUSO-Balloon will be tested to verify: • Capability of protecting the detector from bright events • Measure their light curve and intensity 250 pC
The observation principle of JEM-EUSO duration ~ 50 – 150 ms Simulation of the light profile observed at the entrance pupil (above) and throught the instrument using the ESAF code
PARAMETERS OF EUSO-BALLOON COMPARED TO JEM-EUSO Maximize performance of EUSO-Balloon keeping parameters as close as possible to JEM-EUSO
First assessments on the EAS observation by EUSO-Balloon Simulation inputs: • Shower simulator SAITAMA Code, version Sato – 2005) • Ray trace code version Takky – 07112011 • Flat PDM • M64 PMT simulation as in JEM-EUSO M64 • Trigger module as in JEM-EUSO • Average nightglow background adapted to EUSO-Balloon (1.4 - 2.8 phe/pix/GTU) • Accepted fake trigger rate ~7 Hz R=10km R=4.2km R=4.2km EAS impact point at ground simulated at distances R < 10 km around the Nadir of the telescope.
phe/GTU Typical event observable by EUSO-Balloon (1) Proton: E = 2·1018eV q = 49.0 f= 213.0 X0 = 3.0 km Y0 = 2.9 km Ypix Xpix Time(GTU) Time(GTU) phe/GTU Event landing in the FoV Ypix Time(GTU) Xpix
phe/GTU Typical event observable by EUSO-Balloon (2) Proton: E = 4·1018eV q = 57.5 f= 188.7 X0 = 9.3 km Y0 = 3.1 km Ypix Xpix Time(GTU) Time(GTU) phe/GTU Event landing outside the FoV Ypix Time(GTU) Xpix
Simulation of event (2) GTU by GTU with background GTU = 1 GTU = 2 Y(pix) Proton: E = 4·1018eV q = 57.5 f= 188.7 X0 = 9.3 km Y0 = 3.1 km X(pix) phe GTU = 3 GTU = 4 <Background>: 1.4 phe/pix/GTU
Simulation of event (2) GTU by GTU with background GTU = 5 GTU = 6 Y(pix) Proton: E = 4·1018eV q = 57.5 f= 188.7 X0 = 9.3 km Y0 = 3.1 km X(pix) phe GTU = 7 GTU = 8 <Background>: 1.4 phe/pix/GTU
Simulation of event (2) GTU by GTU with background GTU = 9 GTU = 10 Y(pix) Proton: E = 4·1018eV q = 57.5 f= 188.7 X0 = 9.3 km Y0 = 3.1 km X(pix) phe GTU = 11 GTU = 12 <Background>: 1.4 phe/pix/GTU
Simulation of event (2) GTU by GTU with background GTU = 13 GTU = 14 Y(pix) Proton: E = 4·1018eV q = 57.5 f= 188.7 X0 = 9.3 km Y0 = 3.1 km X(pix) phe GTU = 15 GTU = 16 <Background>: 1.4 phe/pix/GTU
Simulation of event (2) GTU by GTU with background GTU = 17 GTU = 18 Y(pix) Proton: E = 4·1018eV q = 57.5 f= 188.7 X0 = 9.3 km Y0 = 3.1 km X(pix) phe GTU = 19 GTU = 20 <Background>: 1.4 phe/pix/GTU
EUSO-B. & <B>=1.4 phe/pix/GTU EUSO-B. & <B> =2.8 phe/pix/GTU 7 Hz/PDM ● 80 Hz fake trig. o 7 Hz fake trig. Integrated N. Events [1018,E]eV in 10h Trigger efficiency (%) Efficiency=1 & 1.5 x Aug. flux Efficiency=1 & Auger flux EB & A.fl. & <B>=1.4 phe EB & 1.5xA.fl. & <B>=1.4 phe EB & A.fl. & <B> =2.8 phe Energy(eV) Energy(eV) 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.
CONCLUSIONS • EUSO-Balloon 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). • A first simulation study has been performed to understand the effective energy threshold of EUSO-Balloon and its possibility to detect showers in a 10h flight. • Results confirm the capability of the instrument of detecting primary cosmic rays of energy E>1018 eV. • Due to the low cosmic ray flux the detection of a couple of events will require few days exposure time (dependent on the sky background condition), therefore the detection of the first air shower from the edge of the space will most probably require more than one flight.