Preliminary analysis of EUSO - TA data

The EUSO{TA detector is a pathfinder for the JEM-EUSO project and is currently installed in Black Rock Mesa (Utah) on the site of the Telescope Array fuorescence detectors. Aim of this experiment is to validate the observation principle of JEM-EUSO on air showers measured from ground. The experiment gets data in coincidence with the TA triggers to increase the likelihood of cosmic ray detection. In this framework the collaboration is also testing the detector response with respect to several test events from lasers and LED flashers. Moreover, another aim of the project is the validation of the stability of the data acquisition chain in real sky condition and the optimization of the trigger scheme for the rejection of background. Data analysis is ongoing to identify cosmic ray events in coincidence with the TA detector. In this contribution we will show the response of the EUSO-TA detector to all the different typologies of events and we willshow some preliminary results on the trigger optimization performed on such data

EUSO-SPB1 mission and science

The Extreme Universe Space Observatory on a Super Pressure Balloon 1 (EUSO-SPB1) was launched in 2017 April from Wanaka, New Zealand. The plan of this mission of opportunity on a NASA super pressure balloon test flight was to circle the southern hemisphere. The primary scientific goal was to make the first observations of ultra-high-energy cosmic-ray extensive air showers (EASs) by looking down on the atmosphere with an ultraviolet (UV) fluorescence telescope from suborbital altitude (33 km). After 12 days and 4 h aloft, the flight was terminated prematurely in the Pacific Ocean. Before the flight, the instrument was tested extensively in the West Desert of Utah, USA, with UV point sources and lasers. The test results indicated that the instrument had sensitivity to EASs of ⪆ 3 EeV. Simulations of the telescope system, telescope on time, and realized flight trajectory predicted an observation of about 1 event assuming clear sky conditions. The effects of high clouds were estimated to reduce this value by approximately a factor of 2. A manual search and a machine-learning-based search did not find any EAS signals in these data. Here we review the EUSO-SPB1 instrument and flight and the EAS search

Cosmic ray oriented performance studies for the JEM-EUSO first level trigger

JEM-EUSO is a space mission designed to investigate Ultra-High Energy Cosmic Rays and Neutrinos (E > 5 ⋅ 1019 eV) from the International Space Station (ISS). Looking down from above its wide angle telescope is able to observe their air showers and collect such data from a very wide area. Highly specific trigger algorithms are needed to drastically reduce the data load in the presence of both atmospheric and human activity related background light, yet retain the rare cosmic ray events recorded in the telescope. We report the performance in offline testing of the first level trigger algorithm on data from JEM-EUSO prototypes and laboratory measurements observing different light sources: data taken during a high altitude balloon flight over Canada, laser pulses observed from the ground traversing the real atmosphere, and model landscapes reproducing realistic aspect ratios and light conditions as would be seen from the ISS itself. The first level trigger logic successfully kept the trigger rate within the permissible bounds when challenged with artificially produced as well as naturally encountered night sky background fluctuations and while retaining events with general air-shower characteristics

The Mini-EUSO telescope on board the International Space Station: Launch and first observations

Mini-EUSO is a telescope that observes the Earth from the International Space Station by recording ultraviolet emissions (290–430 nm) of cosmic, atmospheric and terrestrial origin with a field of view of 44◦ and on different time scales, from a few microseconds upwards. The scientific objectives are manifold and span several fields of research: Ultra-High Energy Cosmic Rays, atmospheric phenomena such as ELVEs, meteors and meteoroids, maps of the Earth night-time ultraviolet emissions and others. In this paper we will describe the instrument, the launching phase and we will discuss some of its first observations

Determination of the sensitivity and the detection performances of the UV camera pixels of the EUSO-BALLOON instrument

International audienceRecently, the EUSO-BALLOON instrument, the pathfinder for future space telescopes of the JEM-EUSO family, has been flown during one night in the stratosphere by CNES. The recording of light intensity emitted from earth or its atmosphere by its fast and high-resolution pixel UV camera was one of the main goals of this mission. We present an analysis on the in-flight UV camera calibration data. These data allow the extraction of the signal and background components in the recorded photoelectron count spectrum for each pixel, under the assumption of a parameterised multi-component statistical model describing the experimental setup. We assess the detection performances such as the detection sensitivity, the signal to noise ratio. We discuss as well the implication of this calibration in the estimation of the statistical and systematic errors on the photoelectron rates measurement

Using two-photon statistical contribution in the detection of telescopes EUSO

International audienceThe JEM-EUSO (Extreme Universe Space Observatory on Japanese Experiment Module) experiment is about a space telescope that will be installed on the ISS in 2020. The UHECR study aims to improve by a factor of 100 the current measures of Pierre-Auger observatory. The telescope EUSO-Balloon, which was technologically validated in 2014 was the first prototype with the whole chain of detection of telescope JEM-EUSO. SPB-EUSO and MINI-EUSO are the next projects with the same PDM that JEM-EUSO. The principle of detection is based on the capture of individual UV photons which refers to the fluorescence produced by the EAS interaction with Earth's atmosphere. The flow of this fluorescence light is so weak that requires an instrument with 100% efficiency for the detection of one photon and that is the case of EUSO telescopes. This document is a final study of the performance of the telescope EUSO-Ballon. More specifically, a method for information retrieval pixels with weak sensitivity was developed. To achieve this, we use 2-photon contribution on the pulse of an event, as the short-time detection obeys the Poisson distribution. Homogenization of the sensitivity of pixels is critical to trigger algorithms. Also the deterioration of the sensitivity of detection in each channel is inevitable. Thus, this method is useful for recalibration cases, where the sensitivity of one photon’s detection decreases dramatically. As the method uses a curve generated by changing the threshold of discrimination of the measure, it is valid for all EUSO telescopes and it will be most useful in the space, where the manipulation of the instrument is limited

Photoelectron counting rate measurements in the UV camera during the EUSO-BALLOON night flight

International audienceEUSO-Balloon is a prototype for the future space telescope JEM-EUSO aiming to detect UV emissions in the Earth's atmosphere (cosmic air showers, meteorites, airglow, etc). It successfully completed its first flight operated by the CNES over Ontario, Canada, in August 2014. One of the main goals is to measure the photoelectron rate performed by its UV camera. These measurements, corrected from noise contamination, are presented including their time variation. a particular emphasis is put on the determination of the statistical and systematic errors using the relative calibration that was made for all the 2304 pixels. Possible improvements of these performances are discussed in the perspective of future flights

Performance of the EUSO-Balloon FUV camera

International audienceJEM-EUSO [1] is intended to be a space-borne fruorescence telescope onboard of JEM/EF(Japanese Experimental Modeul/Exposure Facility) on the International Space Station (ISS). Themain goal of the JEM-EUSO project is to detect the Extensive Air Showers (EAS) produced bythe Extreme Energy Cosmic Rays (EECRs) with energies above 1019eV from the extragalacticobjects. As a pathfinder, the JEM-EUSO collaboration is currently developing a balloon-bornefluorescence telescope experiment, called EUSO-Balloon, funded by CNES, the French spaceagency. It will perform end-to-end tests of the JEM-EUSO subsystems and instrumental concept,and measure the UV background for space-based EECR detectors. It involves several French institutes(LAL, APC and IRAP) as well as several key institutes of the JEM-EUSO collaboration.The EUSO-Balloon instrument consists of an UV telescope and an infrared camera. The UVtelescope will be operated at an altitude of 40 km to observe the background and possibly signalphotons in the fluorescence UV range (290-430 nm), which are emitted along shower tracks generatedby ultra high energy cosmic rays with energies above 1018eV interacting with the earth’satmosphere. The balloon experiment will be equipped with electronics and acquisition systems,as close as possible to the ones designed for the UV telescope of main JEM-EUSO instrument.The past years have been devoted to the design, the fabrication and the tests of the prototypeboards of the PDM, of the digital processor, and the flight models of optics, electronics and theIR camera for EUSO-Balloon.Here we focus on the PDM, the core element of the JEM-EUSO focal surface. We first describeall key items of the PDM, from the photodetectors to the FPGA board, the first stage of the dataprocessing (DP). We then report on the tests carried out on the integration to assess their functionalityand their suitability for a balloon mission

Absolute calibration of the photon detector module of the EUSO-Balloon experiment and immprovements for future missions

International audienceEUSO-Balloon is a balloon borne mission operated by CNES during a one-night flight in August 2014 over the Ontario forest, in Canada, at 38 km altitude. The payload is a technological demonstrator for the Extreme Universe Space Observatory (JEM-EUSO) aiming at the detection of Extensive Air Showers (EAS) induced by Ultra High Energy Cosmic Rays (UHECR) from the International Space Station (ISS). The photon detection module of EUSO-Balloon consists in a square assembly of 36 Multi-Anodes Photomultiplier Tubes for a total of 2,304 pixels. The characterization at the single photoelectron level in laboratory has been processed before flight in a dedicated black box. After-flight calibration to check possible decrease of gain and efficiency of PMTs has been also carried out. Finally we discuss the upgrade of the detector module to improve the gain and the signal to noise ratio as well as the dynamic range of the readout electronics. The significant progresses made on these aspects represent a first milestone for the R&D of future EUSO-like missions