Evaluation of detector Mini-EUSO to study Ultra High-Energy Cosmic Rays and Ultra Violet light emissions observing from the International Space ...
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Evaluation of detector Mini-EUSO to study
Ultra High-Energy Cosmic Rays and Ultra
Violet light emissions observing from the
International Space Station
Hampus König
Space Engineering, master's level
2019
Luleå University of Technology
Department of Computer Science, Electrical and Space Engineering
Luleå University of Technology
Master Thesis
Evaluation of detector Mini-EUSO to
study Ultra High-Energy Cosmic Rays
and Ultra Violet light emissions
observing from the International Space
Station
Author Supervisor
Hampus König Dr. Marco Casolino
Examiner
Dr. Johnny Ejemalm
2019
Abstract Under the name EUSO, or Extreme Universe Space Observatory, are multiple instruments where some are currently under design or construction and others have concluded their mission. The main goal they have in common is to detect and analyse cosmic rays with very high energies by using the Earth's atmosphere as a detector. One instrument is called Mini-EUSO, will be placed on the international space station during 2019, and its engineering model is currently being used to collect data and test the function of dierent components. The engineering model dier from the full scale instrument, and it is also possible to use it for other purposes as well. In this thesis, some of the collected data is used to analyse and compare the engineering models speci cation to the full Mini-EUSO instrument, with focus on eld of view, inert areas on the sensor and its general function. Objects, such as stars, meteors and satellites were also detected, and used in the tests. In addition a short test regarding the possibility to use the instrument to detect plastic residing in the ocean is made, by utilizing uorescent properties of the plastics. The thesis came to the conclusion that some adjustments needed to be made on the engineering model, but also that the speci cations of it was within expected ranges. Several of the objects found can also be used to improve detection algorithms. In addition, the preliminary tests regarding plastic detection in the ocean, have positive results.
Acknowledgement
During my thesis I've had help from a lot of dierent people and organizations, and I would
like to thank each and every one of them.
First of all, I would like to thank Mini-EUSO's and EUSO-TA's P.I. (Principal Inves-
tigator), and my supervisor Marco Casolino, who made this thesis possible. I would also
like to thank the Chief scientist of the Computational Astrophysics Laboratory, Toshikazu
Ebisuzaki, who accepted me to RIKEN in Wako-shi, Japan.
I also met a lot of people during my stay that deserve a lot of appreciation, in particular
Lech Piotrowski, Carl Blaksley, Georgio Cambie and Sara Turriziani who with great patience
withstood many questions. I also want to thank Tomoko Ohata and Keiko Tokuda for
helping me with everything and anything regarding visa, living accommodations and daily
life at RIKEN.
In addition I would like to thank the Sweden Japan Foundation and Seth M. Kempes
scholarship foundation for the very generous scholarships that helped my stay in Japan
immensely.
I also want to thank my family and friends for the support, especially during the more
intense periods where the banter and discussions lifted the mood.
Contents
Glossary vii
1 The EUSO Program 1
1.1 History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Common design in EUSO-projects . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.1 Focal Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.2 Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.3 Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 EUSO-TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 EUSO-Balloon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.5 EUSO-SPB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.6 EUSO-SPB2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.7 Mini-EUSO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.8 K-EUSO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.9 JEM-EUSO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.10 POEMMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2 Science objectives 20
2.1 Cosmic Rays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.1.1 History and Background . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.1.2 Cosmic-Ray energies and ux . . . . . . . . . . . . . . . . . . . . . . . 21
2.1.3 GreisenZatsepinKuz'min limit . . . . . . . . . . . . . . . . . . . . . 21
2.1.4 Extensive Air Showers . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.2 Meteors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2.1 History and Background . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.3 Plastic pollution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.3.1 History and Background . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.4 Nuclearites and Strange Quark Matter . . . . . . . . . . . . . . . . . . . . . . 26
2.4.1 History and Background . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.4.2 Types of nuclearites . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.5 Atmospheric phenomena . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.5.1 History and Background . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.5.2 Sprite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.5.3 Elves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.6 Orbital debris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.6.1 History and Background . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.6.2 Current status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.7 Bioluminescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.7.1 History and Background . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.7.2 Detection of bioluminescence . . . . . . . . . . . . . . . . . . . . . . . 29
3 Mini-EUSO engineering model 30
4 SNR analysis 32
4.1 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.2 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
i
5 Object detection 37
5.1 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.2 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.2.1 First data-set, Run 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.2.2 Second data-set, Run 5 . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.3.1 First data-set, Run 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.3.2 Second data-set, Run 5 . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
6 Veri cation of engineering model 53
6.1 Alignment of sub-parts of instrument . . . . . . . . . . . . . . . . . . . . . . . 53
6.1.1 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6.1.2 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6.1.3 Result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.1.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.2 Determining Field of View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.2.1 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.2.2 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
6.2.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
6.2.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
6.3 Dead-band between pixels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
6.3.1 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
6.3.2 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
6.3.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
6.3.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
7 Plastic analysis 60
7.1 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
7.2 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
7.2.1 Preparations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
7.2.2 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
7.2.3 Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
7.2.4 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
7.3 Result . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
7.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
8 Further work 63
References 64
ii
List of Tables
1.1 EUSO-TA parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 EUSO-Balloon parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3 EUSO-SPB parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.4 EUSO-SPB2 parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.5 Mini-EUSO parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.6 K-EUSO parameters, previous design proposals . . . . . . . . . . . . . . . . . 16
1.7 K-EUSO parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.8 JEM-EUSO parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.9 POEMMA parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.1 Satellite path information, used for estimation of angular velocity in equation
5.18. Positions are from lower left corner of a single PDM . . . . . . . . . . . 49
6.1 Estimation of FoV for the pixels on Mini-EUSO engineering model . . . . . . 57
iii
List of Figures
1.1 General overlook on what can be detected from an EAS, example histogram
in gure (1.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Image showing uorescent light and two dierent types of Cherenkov radiation
and their distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 How the dierent "blocks" refer to each other in the EUSO-Projects. From
left to right, Multi-Anode Photon Multiplier Tube, Elementary Cell, Photo-
Detector Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 (a) shows a MAPMT with and without a glued BG3 lter and b shows the
nitrogen peaks and transmission window of the lter . . . . . . . . . . . . . . 3
1.5 (a) Image of how a Fresnel Lens is compared to a conventional lens. (b) Image
of test of the lenses being carried out . . . . . . . . . . . . . . . . . . . . . . . 3
1.6 The ASIC module used for Mini-EUSO . . . . . . . . . . . . . . . . . . . . . 4
1.7 EUSO-TA in front of BRM-FD at the Telescope Array in Utah, USA . . . . . 4
1.8 Data retrieved from EUSO-TA (a) compared to simulated data (b) and the
corresponding real data from BRM-FD (c). Data shows a particle with
1 1018 eV, that lasted 2.5 µs. The marked area in gure (c) corresponds
to (a) [3] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.9 Flightpath of the EUSO-Balloon. Launch site to the right. The balloon was
launched from Timmins Stratospheric Balloon Base Ontario, Canada . . . . . 7
1.10 a: Relative UV intensity map in logarithmic scale with relative values to
the mean of UV background intensity. Parts with high intensity represent
arti cial light, red and light blue areas are related to clouds and dark blue
areas indicate the lowest values of UV background. b: IR radiation map
where scale is relative to the mean of IR radiation. From [8] . . . . . . . . . . 7
1.11 The focal surface used in EUSO-SPB1, the small array based on Silicone is
shown to the right of the PDM in rightmost image . . . . . . . . . . . . . . . 8
1.12 One laser pulse shown with 2.5 µs between each image. The axes show the
position of the dierent PMTs in one PDM . . . . . . . . . . . . . . . . . . . 9
1.13 EUSO-SPB1 launch, and ight data [9] . . . . . . . . . . . . . . . . . . . . . 9
1.14 (a) shows one single PDM, and (b) shows a rendered overview of Mini-EUSO 12
1.15 An overview of the trigger used in Mini-EUSO . . . . . . . . . . . . . . . . . 13
1.16 One of the K-EUSO's proposed focal surface designs [16] . . . . . . . . . . . . 14
1.17 (a) shows the proposed Baseline design, and (b) shows the proposed METS
design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.18 (a), overview of the Schmidt design and (b) a simulation of light in the same
design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.19 Construction scheme of the JEM-EUSO Focal Surface . . . . . . . . . . . . . 17
1.20 POEMMA Overview and how it is intended to function . . . . . . . . . . . . 18
1.21 (a) shows a simulation of the optical design and (b) shows the layout of the
focal surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.1 Energy spectrum of cosmic rays [36] . . . . . . . . . . . . . . . . . . . . . . . 21
2.2 Figure of an electromagnetic cascade (a) and a hadronic shower (b) [43] . . . 22
2.3 Image showing one particular bright meteor during the Leonidas Shower in
2009 [50] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.4 How many people view the Great Paci c Garbage Patch. In reality it is just
a slightly increased abundance of plastics . . . . . . . . . . . . . . . . . . . . 26
2.5 Dierent atmospheric phenomena. Image Credit: NOAA . . . . . . . . . . . . 27
2.6 The number of tracked/known object in orbit as of rst quarter of 2018. [67] 28
iv
2.7 Bioluminescence as seen from over the Arabian Sea [68] . . . . . . . . . . . . 29
3.1 (a) and (b) shows the engineering model from the front and side respectively 30
3.2 The engineering model assembled with the lens with reduced size due to
smaller focal surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.3 The engineering model placed at Pina Torinese taking measurements . . . . . 31
4.1 The projected path of the star Spica on the detector. The values shown are
the average of the photons each PMT detect during 40.96 ms . . . . . . . . . 32
4.2 (a) shows the photon count for a single pixel over time and (b) shows the
average photon count for a single pixel over time . . . . . . . . . . . . . . . . 33
4.3 Pixel [21][26], both signal and background together in (a), and their isolated
parts with background in b) and signal in (c) . . . . . . . . . . . . . . . . . . 33
4.4 Pixel [21][26], both isolated background in (a) and isolated signal in (b) with
curves tted (the red line) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.5 9 adjacent pixels. Instrument is rst facing empty space, with the star Spica
entering the view later. Time on x-axis. . . . . . . . . . . . . . . . . . . . . . 34
4.6 (a) shows the photon count of the 9 pixels in gure 4.5 spatially integrated
over time and (b) shows the average photon count of the 9 pixels in gure 4.5
spatially integrated over time . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.7 Spatially integrated pixels [20-22][25-27], both signal and background together
in (a), and their isolated parts with background in b) and signal in (c) . . . . 35
4.8 Spatially integrated pixels [20-22][25-27], both isolated background in (a) and
isolated signal in (b) with curves tted (the red line) . . . . . . . . . . . . . . 36
5.1 Run4: Overview of the full Elementary Cell. Original data in (a), oset
adjusted data in (b), and zoomed data in (b) for better visibility . . . . . . . 37
5.2 Dierent view of the data, where one axis shows time, the other shows which
pixel and one the average photon count data . . . . . . . . . . . . . . . . . . 38
5.3 Signal of each of the dierent MAPMTs . . . . . . . . . . . . . . . . . . . . . 38
5.4 Run5: Overview of the full Elementary Cell. Original data in (a), oset
adjusted data in (b), and zoomed data in (c) for better visibility . . . . . . . 39
5.5 Dierent view of the data, where one axis shows time, the other shows which
pixel and one the average photon count data . . . . . . . . . . . . . . . . . . 39
5.6 Signal of each of the dierent MAPMTs . . . . . . . . . . . . . . . . . . . . . 40
5.7 Star 1: Shows time and space projection of the star. Top shows the informa-
tion as collected, and bottom shows the adjusted movement of the star due
to error in lower right MAPMT . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.8 Star 2: Shows time and space projection (movement due to earth's rotation) . 41
5.9 Star 3: Shows time and space projection of the star . . . . . . . . . . . . . . . 41
5.10 Star 4: Shows time and space projection of the star . . . . . . . . . . . . . . . 42
5.11 Star 5: Shows time and space projection of the star. Top shows the informa-
tion as collected, and bottom shows the adjusted movement of the star due
to error in lower right MAPMT . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.12 Star 6: Shows time and space projection of the star . . . . . . . . . . . . . . . 42
5.13 Meteor 1: Shows time and space projection, or trajectory of the meteorite . . 43
5.14 Meteor 2: Shows time and space projection, or trajectory of the meteorite.
Top shows the information as collected, and bottom shows the adjusted tra-
jectory of the meteor due to error in lower right MAPMT . . . . . . . . . . . 43
5.15 Meteor 3: Shows time and space projection, or trajectory of the meteorite.
Top shows the information as collected, and bottom shows the adjusted tra-
jectory of the meteor due to error in lower right MAPMT . . . . . . . . . . . 44
v
5.16 Star 1: Shows time and space projection of the star. The timing and direction
of the star seems to be accurate, but an empty space is seen in the left image.
This might be due to small discrepancies in if the surfaces of the MAPMTs
are fully parallel or not, along with a slightly bigger distance between two
MAPMTs compared to two PMT within the same MAPMT. Slightly longer
analysis with some of the twilight present to capture more of the star . . . . 45
5.17 Star 2: Shows time and space projection of the star. Top shows the informa-
tion as collected, and bottom shows the adjusted movement of the star due
to error in lower right MAPMT . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.18 Star 3: Shows time and space projection of the star. Slightly longer analysis
with some of the twilight present to capture more of the star . . . . . . . . . 46
5.19 Star 4: Shows time and space projection . . . . . . . . . . . . . . . . . . . . . 46
5.20 Star 5: Shows time and space projection of the star. The timing and direction
of the star seems to be accurate, but an empty space is seen in the left image.
This might be due to small discrepancies in if the surfaces of the MAPMTs
are fully parallel or not, along with a slightly bigger distance between two
MAPMTs compared to two PMT within the same MAPMT. Slightly longer
analysis with some of the twilight present to capture more of the star . . . . 47
5.21 Satellite: Shows time and space projection of the satellite. Top shows the
information as collected, and bottom shows the adjusted movement of the
satellite due to error in lower right MAPMT . . . . . . . . . . . . . . . . . . . 47
5.22 The satellite was identi ed to be Meteor-1-31-Rocket. Orbit is shown for that
speci c satellite at a nearby time interval. Image from www.calsky.com . . . 48
5.23 Angles for estimating the angular velocity as seen from the centre of the earth 49
5.24 Meteor 1: Shows time and space projection, or trajectory of the meteorite . . 50
5.25 Meteor 2: Shows time and space projection, or trajectory of the meteorite.
Top shows the information as collected, and bottom shows the adjusted tra-
jectory of the meteor due to error in lower right MAPMT. . . . . . . . . . . . 51
5.26 Meteor 3: Shows time and space projection, or trajectory of the meteorite . . 51
5.27 Meteor 4: Shows time and space projection, or trajectory of the meteorite . . 51
6.1 Spicas movement between two MAPMTs when the entire instrument is being
moved. The images shown are from when the instrument is being adjusted . . 53
6.2 Satellite Meteor 1-31 Rocket before the adjusted MAPMT, chronological or-
der. Using ETOS, analysis program for the EUSO collaboration . . . . . . . . 54
6.3 The adjustment scheme used for analysing data that is visible in the MAPMTs
with the error. Axes show the x- and y-position . . . . . . . . . . . . . . . . . 54
6.4 Satellite Meteor 1-31 Rocket after the adjusted MAPMT, chronological order.
Same data is used, but another way of displaying it after the corrected MAPMT 55
6.5 Dierent focus on the focal surface . . . . . . . . . . . . . . . . . . . . . . . . 56
6.6 The idea behind the dead-band can be summed up in this gure, the marked
area is the same dead-band shown twice . . . . . . . . . . . . . . . . . . . . . 58
6.7 Star 3. Shows the path of the star, and the dips between pixels, which can
be used to estimate the dead-bands . . . . . . . . . . . . . . . . . . . . . . . . 58
6.8 View of dead-bands between pixels for star 3 . . . . . . . . . . . . . . . . . . 58
6.9 Star 3. Marked for where the dead-band is visible, two visible limits for
dierent parts of the observed star, as explained in gure (6.6) . . . . . . . . 59
7.1 Set-up for measuring plastics UV-emission compared to its re ection. The
black tube in front of the spectrometer is used to reduce surrounding light,
and/or re ections from other sources. The set-up was placed in a black box . 61
7.2 The resulting graphs of the two measurements (re ection and emittance) as
well as the dierence between them after they are normalized. . . . . . . . . . 62
viGlossary
ASIC Application-Speci c Integrated Circuit
BRM-FD Black Rock Mesa Fluorescence Detectors
CCB Cluster Control Boards
CHAMP CHarged Massive Particle
CLF Central Laser Facility
CMB Cosmological Microwave Background
CNES Centre national d'études spatiales
CR Cosmic Ray
DM Dark Matter
EAS Extensive Air Shower
EC Elementary Cell
EHECR Extremly High Energy Cosmic Rays, sometimes mentioned as EECR
ELIPS European Life and Physical Sciences in Space Programme
ELS Electron Light Source
ELVES Emission of Light and Very low frequency perturbations due to Electromagnetic
pulse Sources
EM Electromagnetic
ESA European Space Agency
EUSO Extreme Universe Space Observatory
EUSO-SPB EUSO Super Pressure Balloon
EUSO-SPB2 EUSO Super Pressure Balloon 2
EUSO-TA Extreme Universe Space Observatory - Telescope Array
FoV Field of View
FPGA Field-Programmable Gate Array
FS Focal Surface
GPGP Great Paci c Garbage Patch
GSFC Goddard Space Flight Center
GTU Gate Time Unit
GZK limit GreisenZatsepinKuzmin limit
HV High Voltage
ICRC International Cosmic Ray Conference
viiISS International Space Station
JAXA Japan Aerospace Exploration Agency
JEM Japanese Experiment Module
JEM-EUSO Japanese Experiment Module - Extreme Universe Space Observatory
K-EUSO KLYPVE-EUSO
LHC Large Hadron Collider
lidar Light Radar
MACHO MAssive Compact Halo Object
MAPMT Multi-Anode Photomultiplier Tube
MASS Maximum-energy Auger (Air)-Shower Satellite
METS Multi-Eye Telescope System
Mini-EUSO Multiwavelength Imaging New Instrument - Extreme Universe Space Obser-
vatory
NASA National Aeronautics and Space Administration
OWL Orbiting Wide angle Light concentrator
P.I. Principal Investigator
PDM Photo-Detector Module
PMMA PolyMethyl-MethAcrylate
PMT Photomultiplier Tube
POEMMA Probe of Extreme MultiMesenger Astrophysics
radar RAdio Detection And Ranging or RAdio Direction And Ranging
SINP MSU Skobeltsyn Institute of Nuclear Physics Lomonosov Moscow State University
SiPM Silicon Photo Multiplier
SNR Signal to Noise Ratio
SOCRAS Satellite Observatory of Cosmic Ray Showers
SPRITE Stratospheric/mesospheric Perturbations Resulting from Intense Thunderstorm
Electri cation
SSN Space Surveillance Network
TA Telescope Array
TLE Transient Luminous Event
TUS Tracking Ultraviolet Set-up
UHECR Ultra Hight-Energy Cosmic Rays
USSTRATCOM United States Strategic Command
UV Ultra Violett
WIMP Weakly Interacting Massive Particle
viiiCHAPTER 1
The EUSO Program
The EUSO program consists of several participating countries, institutes and researchers.
The countries involved are among others, Italy, Japan, Poland, Russia, South Korea, Sweden
and USA. In total 16 countries, 84 institutes and over 300 researchers [1].
Within the EUSO-collaboraton, there are several phenomena that is of interest to in-
vestigate, with the main being comic rays. Other objects and phenomena of interest are,
meteors, nuclearites, strange quark matter and atmospheric phenomena such as Sprites and
Elves. Under consideration and evaluation are also the possibilities to detect orbital debris
for removal, and the detection of plastics in the ocean as well as bioluminescence.
All of these phenomena and objects are to be analysed in a part of the light spectrum,
which correspond to UV (Ultra Violett)-light, the 290 nm to 430 nm spectrum. Speci c for
the main objective, the UHECR (Ultra Hight-Energy Cosmic Rays), it will detect a product
of the particles when they enter the atmosphere, namely the Extensive Air Shower. By
measuring that, the energy and direction of the UHECR can be estimated.
1.1 History
Back in the early 1980's, one experiment was proposed to analyse cosmic radiation. The
SOCRAS (Satellite Observatory of Cosmic Ray Showers). It was presented at the 17th ICRC
(International Cosmic Ray Conference) in Paris and was proposed to launch a satellite to
500 km to 600 km above the earth that would observe an area of about 10 000 km2 . An
example is seen in gure 1.1 with the distribution of what kind of light detected in gure
1.2.
In the 1980's the project was forgotten, mainly due to lack of needed technologies, but in
1995, the idea once again was discovered by Yoshiyuki Takahashi and presented in the 24th
ICRC in Rome, but this time under the name MASS (Maximum-energy Auger (Air)-Shower
Satellite).
Figure 1.1: General overlook on what can be detected from an EAS, ex-
ample histogram in gure (1.2)
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Figure 1.2: Image showing uorescent light and two dierent types of
Cherenkov radiation and their distribution
During 1995, the project also received a second name, which was "Airwatch" which
evolved into EUSO (Extreme Universe Space Observatory), and a feasibility study started
in 2001, and was completed in 2004.
Airwatch evolved into EUSO, and a study regarding the feasibility started in 2001, which
was completed in 2004 with a positive result. However, due to some incidents, with accident
of the space shuttle Columbia, being one, the project was put on hold. In 2006 the project
was rede ned and instead of a satellite, an observatory was proposed to be placed on the
JEM (Japanese Experiment Module) on the ISS (International Space Station), and the
project was also renamed to JEM-EUSO (Japanese Experiment Module - Extreme Universe
Space Observatory). A kick-o was held in 2006 at RIKEN, and in 2010 the EUSO mission
was included in the ELIPS (European Life and Physical Sciences in Space Programme) of
the ESA (European Space Agency) [2].
1.2 Common design in EUSO-projects
Many of the dierent projects in the EUSO project has a similar foundation when built.
Among the bigger components, the focal surface, the optics and the electronics are the same,
or very similar. A lot of the software are also used on several experiments.
1.2.1 Focal Surface
The PMT (Photomultiplier Tube) is made by the company Hamamatsu, and comes in a
prearranged set of 64 in a 8 8 square pattern. The components name is Hamamtsu-
R11265U and the component is called MAPMT (Multi-Anode Photomultiplier Tube). Four
of these MAPMT in a 22 pattern make up one EC (Elementary Cell), and in turn 9 EC
in a 33 pattern made a PDM (Photo-Detector Module). That is a total of 36MAPMT
or 2304 pixels, and can be seen in gure 1.3.
Figure 1.3: How the dierent "blocks" refer to each other in the EUSO-Projects. From left to
right, Multi-Anode Photon Multiplier Tube, Elementary Cell, Photo-Detector Module
2 of 68 THE EUSO PROGRAMLuleå University of Technology Hampus König
The PDMs can then be combined in dierent shapes, varied from one as in Mini-EUSO
and EUSO-Balloon up to over one hundred as was planned on JEM-EUSO.
1.2.2 Optics
On top of each MAPMT, there is a thin lter glued to the surface as seen in gure 1.4a.
This is to limit the light that reaches the PMT. When searching for CR (Cosmic Ray), one
of the ways to detect them are by looking for the uorescent light, that is strong in the
UV-range. The lter makes sure only light within the wavelengths between 290 nm-430 nm.
The lter is called BG3, and is of the brand Schott. The transmission window of the lter
and the nitrogen peaks due to the uorescent light can be seen in gure 1.4b.
(a) (b)
Figure 1.4: (a) shows a MAPMT with and without a glued BG3 lter and b shows the nitrogen
peaks and transmission window of the lter
On top of the ltering, many of the projects in the EUSO-collaboration uses the lens
called Fresnel lens. It is a smaller and lighter lens compared to a conventional lens, but still
retains most of the needed properties. The amount material used, and thus the weight of
the lens, are less than a conventional lens. See gure 1.5a for how the dierence look in a
cross-section of the lenses.
(a) (b)
Figure 1.5: (a) Image of how a Fresnel Lens is compared to a conventional lens.
(b) Image of test of the lenses being carried out
Depending on which project the lens belongs to, the size varies, from about 25 cm in
diameter for Mini-EUSO as seen in gure 1.5b, up to over 2m for K-EUSO (KLYPVE-
EUSO).
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1.2.3 Electronics
The electronics behind the FS (Focal Surface) are for several projects almost the same.
One PDM is connected to a total six ASIC (Application-Speci c Integrated Circuit)-boards,
where one can be seen in gure 1.6 and each ASIC-board have six ASIC-chips, in total one
for each MAPMT. The six ASIC-boards are then connected to a single PDM-board, and
a Zynq FPGA (Field-Programmable Gate Array)-board, which handles rst level triggers,
and that entire package make a full PDM including much of the needed electronics. This
module will be connected to a CCB (Cluster Control Boards) which handles second level
triggers, and depending on which project it is, it can handle 1-8 PDM-boards. From there
the connection goes to a CPU-board that controls storage of the data collected.
Figure 1.6: The ASIC module used for Mini-EUSO
1.3 EUSO-TA
Figure 1.7: EUSO-TA in front of BRM-FD at the Telescope Array in Utah, USA
4 of 68 THE EUSO PROGRAMLuleå University of Technology Hampus König
The EUSO-TA (Extreme Universe Space Observatory - Telescope Array), which can
be seen in front of the BRM-FD (Black Rock Mesa Fluorescence Detectors), which is an
instrument in the TA (Telescope Array) project, in gure 1.7, is a prototype and path nder.
Its main goal is to demonstrate and make initial measurements with the technology used
by the EUSO-collaboration. This experiment was installed during 2015, and has since then
had several campaigns where it has been operational to take measurements and test the
equipment.
Due to being placed near the existing instruments from TA project, some auxiliary
equipment are already in place, which can be used by the EUSO-collaboration, for example
light sources such as CLF (Central Laser Facility) and ELS (Electron Light Source), used for
calibration, and an infrastructure already built for the TA project, such as power, grounding
and Ethernet, that can be utilized as long as it is not interrupting the measurements of
instruments in the TA project.
(a) (b)
(c)
Figure 1.8: Data retrieved from EUSO-TA (a) compared to simulated data (b)
and the corresponding real data from BRM-FD (c). Data shows a particle with
1 1018 eV, that lasted 2.5 µs. The marked area in gure (c) corresponds to (a) [3]
One of the main components used for the EUSO-TA is an optical system, which only
THE EUSO PROGRAM 5 of 68Hampus König Luleå University of Technology
allows about 11.6° FoV (Field of View) [4, 3, 5].
EUSO-TA uses one PDM, which consists of 2304 pixels. The signals generated by each
pixel is received by the front-end ASIC, passes through a FPGA, where the rst trigger
algorithms is implemented [5].
A big advantage of having the EUSO-TA near the BRM-FD, is the use of external triggers
which can start the data collection by EUSO-TA. In gure 1.8a one event is recorded which
used BRM-FD as an external trigger. Figure 1.8b shows the simulations of cosmic rays with
the same speci cations as the one recorded and both of these seems to correspond well to
the results in gure 1.8c taken by BRM-FD. In addition, EUSO-TA can use BRM-FD for
an absolute calibration of the instruments.
EUSO-TA is capable of detecting UHECR, which also can be concluded when when using
CLF and ELS as the results are what is being expected.
A short description of EUSO-TA can be seen in table 1.1.
Table 1.1: EUSO-TA parameters
General Data
Status In operation
Built 2015
Shape/Size of lenses Square, 1 m1 m
Detector Hamamatsu R11265-M64
Number of detectors 36
Number of Pixels 2304
Field of View 10.5°11°
Spatial Resolution 0.19°
Temporal Resolution 2.5 µs
1.4 EUSO-Balloon
The EUSO-balloon is a path nder experiment that ew in August 2014, with the help from
CNES (Centre national d'études spatiales). The balloon rose to an altitude of about 40 km.
That in combination with the somewhat small FoV of 12°, the ground area and volume of
air observed is smaller than of what Mini-EUSO (Multiwavelength Imaging New Instrument
- Extreme Universe Space Observatory) is planned to have. The ight was however mainly
used for other purposes than to detect UHECR where one was to be used as a technical
demonstrator. The instrument contained all major technologies that will be used for Mini-
EUSO, including the HV (High Voltage) power supply and switches and the same size FS
of 2304 pixels. In addition it had the front end electronics, infra-red camera and other parts
of the same design as most of the EUSO-projects. Some information is found in table 1.2.
Since the balloon had a limited FoV and altitude, the chance of detecting UHECR is
rather small compared to space based instruments. To assure that some measurements were
taken, a helicopter ew beneath the balloon, and used two kinds of UV-light sources to test
the capturing algorithm among other things [6, 7].
The balloon started its journey in August, 2014 from Timmins Statospheric Balloon Base
in Ontario, Canada. After the launch was towards the west, and it had a successful ight
of about 8h with a maximum altitude close to 38 300 m [6]. The ightpath can be seen in
gure 1.9, where the launch site is shown to the right in the image.
During the ight, the instrument continuously took both UV-imagery and IR-imagery
of the ightpath with results shown in gure 1.10. The ight also did show that the key
technologies used can ful l at least one of the mission parameters for the EUSO-projects yet
to come, namely the UV-background recording of the earth.
6 of 68 THE EUSO PROGRAMLuleå University of Technology Hampus König
Figure 1.9: Flightpath of the EUSO-Balloon. Launch site to the right. The balloon was
launched from Timmins Stratospheric Balloon Base Ontario, Canada
(a) UV-background
(b) IR-background
Figure 1.10: a: Relative UV intensity map in logarithmic scale with relative values to the
mean of UV background intensity. Parts with high intensity represent arti cial light, red
and light blue areas are related to clouds and dark blue areas indicate the lowest values of
UV background. b: IR radiation map where scale is relative to the mean of IR radiation.
From [8]
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Table 1.2: EUSO-Balloon parameters
General Data
Status Launched
Launched 2014-08-24
Mass 250 kg
Dimensions (L W H) 1.24 m 1.24 m 2.96 m
Shape/Size of lenses Fresnel lens, Square, 1 m 1 m
Detector Hamamatsu R11265-103-M64
Number of detectors 36
Number of Pixels 2304
Field of View 12° 12°
Spatial Resolution 0.25° 0.25°
Temporal Resolution 2.5 µs
1.5 EUSO-SPB
EUSO-SPB (EUSO Super Pressure Balloon) was own in 2017, and was, broadly speaking,
an upgraded version on the previous EUSO-Balloon. It has one PDM, fresnel lenses with
the size 1m 1 m, and about the same FoV. A collection of data can be seen in table 1.3.
The main dierence was the triggering algorithm and the altitude, which in this ight
was about 33.5 km. Some additional parts were added to evaluate new technology, such as
a smaller 256 pixel array which is seen in gure 1.11. It was made by Hamamatsu as the
main detector, but it was based on silicon rather than being based on the bialkali design,
which is two kinds of alkali metals used for the photocathodes.
Figure 1.11: The focal surface used in EUSO-SPB1, the small array based on
Silicone is shown to the right of the PDM in rightmost image
The design was tested before the ight, and it was done so by placing it next to EUSO-
TA in Utah, USA. A signal from a laser was measured and compared to the data from
EUSO-TA and with that information calibration was accomplished and function con rmed.
In gure 1.12 one of those laser pulses are shown.
It was launched in 2017 from New Zealand which can be seen in gure 1.13a, and ew east
towards South America. However, bad luck struck, and the balloon slowly leaked Helium.
At rst it could be compensated by reducing the ballast in succession as seen on the ight
data shown in gure 1.13b, but at some point the ballast was depleted. It crashed into the
paci c ocean approximately 12 days and 4 hours after the launch, but even with that limited
ight-time, many hours of data was successfully downloaded.
8 of 68 THE EUSO PROGRAMLuleå University of Technology Hampus König
Figure 1.12: One laser pulse shown with 2.5 µs between each image. The axes
show the position of the dierent PMTs in one PDM
(a) Launch of EUSO-SPB1
(b) Flightcurve of EUSO-SPB1
Figure 1.13: EUSO-SPB1 launch, and ight data [9]
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Table 1.3: EUSO-SPB parameters
General Data
Status Launched
Launched 2017-04-24
Mass 1227 kg
Shape/Size of lenses Fresnel lens, Square, 1m 1m
Detector 1
Bialkali
Detector Hamamatsu R11265-113-M64-MOD2
Number of detectors 36
Number of Pixels 2304
Field of View 11.1° 11.1°
Spatial Resolution 0.25° 0.25°
Temporal Resolution 2.5 µs
Detector 2
SiPM
Detector Hamamatsu S13361-3050AS-08
Number of detectors 4
Number of Pixels 256
1.6 EUSO-SPB2
A second high altitude ight is under planning and is expected to be launched during 2022
from New Zealand. It will dier from the rst balloon experiment and the EUSO-SPB
with a new design and some additional goals. Instead of one downward facing telescope,
it will consist of three independent telescopes, that also will look into Cherenkov radiation
originating from UHECR travelling through the earth's atmosphere.
The preliminary parameters are shown in table 1.4. The path EUSO-SPB2 (EUSO Super
Pressure Balloon 2) will travel is approximately the same as its predecessor EUSO-SPB [10].
Another dierence is the lack of lenses, and instead the use of mirrors as optical systems.
On top of that, the sensors, or focal planes will not be in the same shape as in previous
ights, this time most of the sensors are places in a almost linear fashion. It will be two
rows of ECs for each telescope, 28 ECs long for the two Cherenkov telescopes, and 18 for
the uorescent one.
10 of 68 THE EUSO PROGRAMLuleå University of Technology Hampus König
Table 1.4: EUSO-SPB2 parameters
General Data
Status Design phase
Planned to Launch 2022
Telescope 1
Cherenkov, horizontal events
Shape/Size of lenses Fresnel lens, Square, 1m 1m
Detector Hamamatsu R11265-64
Number of detectors 52
Number of Pixels 3328
Field of View 3.5° 45°
Spatial Resolution 0.2°
Temporal Resolution 2.5 µs
Telescope 2
Upward Cherenkov, from EAS (Extensive Air Shower)
Shape/Size of lenses Fresnel lens, Square, 1m 1m
Detector Hamamatsu R11265-64
Number of detectors 52
Number of Pixels 3328
Field of View 3.5° 45°
Spatial Resolution 0.2°
Temporal Resolution 2.5 µs
Telescope 3
Fluorescent, from EAS
Detector Hamamatsu R11265-103-M64
Number of detectors 36
Number of Pixels 2304
Field of View 3.2° 28.8°
Spatial Resolution 0.2°
Temporal Resolution 2.5 µs
THE EUSO PROGRAM 11 of 68Hampus König Luleå University of Technology
1.7 Mini-EUSO
Mini-EUSO will be the rst space bound mission in the EUSO-program, and is intended
to launch during the second half of 2019. One of the goals Mini-EUSO have, is to map
the earth's UV-radiation, which it will do from the UV-transparent window at the Russian
Zvezda module on the ISS. On top of that, the Mini-EUSO will also analyse atmospheric
phenomena, meteors, search for strange quark matter in the form of nuclearites and both
search for bioluminescence in the oceans along with detecting plastics with the help of its
uorescent properties. Another possible use is to search for space debris and to determine
if it is possible to use additional equipment such as Laser to reduce the amount of debris in
orbit [11].
(a) (b)
Figure 1.14: (a) shows one single PDM, and (b) shows a rendered overview of Mini-EUSO
The Mini-EUSO is based on the same components as many of the previous experiments.
It will consist of one PDM which is seen in gure 1.14a, along with the needed electronics
which among other parts includes ASIC-boards, Zynq-Boards, HV equipment. The lenses
are of fresnel design, and have a round shape, where one is double-sided and the other one
is one-sided. The diameter is roughly 250 mm and have a thickness of about 11 mm. UV-
transparent PMMA (PolyMethyl-MethAcrylate) is the choice of material and due to that
choice along with the design they weigh only about 0.8 kg-0.9 kg each. A drawing of the full
instrument is seen in gure 1.14b and general parameters in table 1.5.
One PDM is equal to 2304 pixels in a square pattern of 48 48 pixels. On the surface,
the BG3 optical lter will be glued, which transmits light in the range of 290 nm-430 nm.
The HV equipment are updated with this instrument. The new design is a Cockroft-
Walton HV-power supply which distributes correct power. It also protects the equipment
from high power surges if a very bright phenomena is detected by the Mini-EUSO, then
within 3 µs it can reduce the high voltage and by doing so, the gain, to a safer value [12].
While Mini-EUSO is placed in the ISS, it will only be connected by power and ground.
The data collected will be stored on hard drives belonging to the instrument itself. The
amount of data can be estimated with calculations and the size of the drives adjusted
accordingly. For example, if it is assumed that 3 B{pixel is recorded, it will store about
507 kB{s worth of data. And assuming an uptime of about 50 %, due to the time spent in
darkness during the orbit (which is a very generous assumption), approximately 660 GB will
be stored each month. That data will be sent down in the form of physical hard drives with
the ISS supply rocket [13].
The amount data stored varies a little depending on how many events that is detected.
An overview of the triggers can be viewed in gure 1.15, but in general the raw data (signal)
from the PMT enters the electronics handling trigger functions. Each data point consists of
the number of photons detected by each PMT during one GTU (Gate Time Unit) which is
2.5 µs.
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For the rst level, the electronics average 8GTUs and compare it to an algorithm based
of a calculated average of 128GTUs. If the limit is passed, the data is placed in a buer.
The next trigger level functions on a similar way. The input in this case is a second
order GTU, which here will be called GTUL2 , which is an average of 128GTUs. A similar
algorithm calculate the limit, and a sum of P GTUL2 is compared to that limit and where
P can be changed as seen t by either adapting software or the EUSO-team. If it passes that
limit the data is also placed in the buer. The nal level is not using a trigger function, but
instead consists of an average of 128GTUL2 which will be called GTUL3 . The dierent
levels of the data streams which consists of the blocks GTU, GTUL2 or GTUL3 are titled
L1, L2 and L3 respectively. The dierences between the blocks are the temporal resolution
which means that L1 can detect CR, while L2 and L3 are more suited towards slower events
such as meteorites and UV-background.
Figure 1.15: An overview of the trigger used in Mini-EUSO
The time each levels single data point have are the following. L1 is 2.5 µs, L2 is 1282.5 µs
or 320 µs and L3 is 128L2 or 128320 µs, which is 40.96 ms. All created L3's are moved to
the buer and creates a full view of the average UV-light continuous during the instrument's
active time. When 128L3 have been stored in the buer they are moved to the storage
along with the L1 and L2 which have been triggered by the algorithms in that time span.
The storage writes to a le, and when 3200L3 have been written to a le, a new le is
created. So the normal size of a le is 3200L3 entries, which determines the time each le
overlooks. It is 131.072 s, or about 2 minute 11 seconds.
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Table 1.5: Mini-EUSO parameters
General Data
Status Under design/construction
Planned launch 2019
Mass 30 kg
Dimensions (L WH) 0.37 m 0.37 m 0.62 m
Shape/Size of lenses Circular, 0.25 m
Detector Hamamatsu R11265-M64
Number of detectors 36
Number of Pixels 2304
Field of View 44°
Spatial Resolution 0.8°
Temporal Resolution 2.5 µs
1.8 K-EUSO
K-EUSO, is one of the EUSO-programs last planned designs, and it is estimated to go to
the ISS under 2022. At the ISS it will be placed in the Russian part, and it will also utilize
a Russian design for a telescope [14], the KLYPVE (sometimes written as KLPVE, which
is a Russian acronym for Kosmicheskie Luchi Predel'no Vysokikh Energii, or cosmic rays of
the highest energies [15]). General parameters for the latest design are found in table 1.7,
and previous designs parameters are found in table 1.6.
KLYPVE have had various iterations in its development, and it started 2010 as a tele-
scope solely proposed by SINP MSU (Skobeltsyn Institute of Nuclear Physics Lomonosov
Moscow State University). In 2012 a preliminary design was nished and it consisted of 10 m2
mirror telescope, positioned on the outside of the ISS. The focal distance were planned to
be about 3 m, and it would have had a FoV of about 7.5°.
The rst iteration of the design could not ful l the needed speci cations to observe
UHECR, so further development was needed. In 2013 a collaboration with the EUSO-
program started, which proposed a new corrective optical element, an additional lens. This
solution was called the Baseline system and would use a conventional focal surface as seen
in gure 1.16 as well as a a preliminary design proposal in gure 1.17a.
Figure 1.16: One of the K-EUSO's proposed focal surface designs [16]
At the same time, a dierent solution was also proposed that would use three detectors
in a certain pattern. This solution is called METS (Multi-Eye Telescope System) and an
idea of how it would look like can be seen in gure 1.17b. The design would increase the
FoV and also require simpler and smaller telescopes which would lead to less disturbances
from the optics.
Some parts still warranted further development as the METS and baseline design had
a complicated aspherical designs of the mirrors and the Fresnel lenses proposed had some
scattering which would reduce the e ciency of the system. Also the previous instrument
called TUS (Tracking Ultraviolet Set-up), that had similar design traits, showed that thun-
derstorms outside the FoV could falsely trigger measurements [17].
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(a) (b)
Figure 1.17: (a) shows the proposed Baseline design, and (b) shows the proposed METS
design
The development continued. This resulted in a Schmidt optical system which was pro-
posed and is shown in gure 1.18a and its functionality simulated in 1.18b. The design also
had a larger FoV than both previous re-designs while still being built out of the same PMT
as most of the EUSO-projects. It would be close to 120.000 pixels for this design.
The aperture of the K-EUSO would still require some corrective optics, but fortunately
there is a lot of dierences compared to the previous designs, which not only reduced the
complexity, but also the weight of said optics.
(a) (b)
Figure 1.18: (a), overview of the Schmidt design and (b) a simulation of light in the same
design
Currently the mission duration is set to two year with the launch planned at 2022 with
a possible extension if ISS will have a prolonged mission duration up to about 6 years [18].
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Table 1.6: K-EUSO parameters, previous design proposals
General Data
Status Under design/construction
Planned launch 2022
Design 1
KLYPVE Original
Shape/Size of mirror Spherical, 3.6 m
Field of View 15°
Spatial Resolution 0.29°
Design 2
KLYPVE Baseline
Shape/Size of mirror Spherical, 3.4 m
Shape/Size of lens Circular, 1.7 m
Detector Hamamatsu R11265-M64
Number of detectors 1872
Number of Pixels 119808
Field of View 28°
Spatial Resolution 0.057°
Temporal Resolution 2.5 µs
Design 3
KLYPVE METS
Shape/Size of mirror 3Spherical, 2.4 m
Shape/Size of lens 3Circular, 1.2 m
Detector Hamamatsu R11265-M64
Number of detectors 2052 (3 684)
Number of Pixels 131328
Field of View 35°
Spatial Resolution 0.075°
Temporal Resolution 2.5 µs
Table 1.7: K-EUSO parameters
General Data
Status Under design/construction
Planned launch 2022
Shape/Size of mirror Spherical, 4m
Detector Hamamatsu R11265-M64
Number of detectors 1872
Number of Pixels 119808
Field of View 40°
Spatial Resolution 0.11°
Temporal Resolution 2.5 µs
16 of 68 THE EUSO PROGRAMLuleå University of Technology Hampus König
1.9 JEM-EUSO
One of the previous major experiments in the EUSO-program is called JEM-EUSO. Un-
fortunately the JEM-EUSO mission was frozen by JAXA (Japan Aerospace Exploration
Agency) due to the restructuring of the space station program of Japan during 2015 [19],
and a new launch was planned to 2017, but that was also cancelled due to nancial reasons
[20]. The future for JEM-EUSO is currently uncertain. With that in mind, the planned
parameters are seen in table 1.8.
The telescope had a design based on the same parts as the most of the instruments in the
EUSO-collaboration. With over 3 105 pixels, the resolution is getting close to somewhere
within 500 m to 550 m on the ground in one dimension, or about 0.07°-0.08°.
One of the main reasons an experiment in this scale hasn't been done before was the lack
of compact, low weight optical systems. The JEM-EUSO intended to solve this by using
Fresnel lenses made out of PMMA. The FS for JEM-EUSO is not a fully square surface, nor
is it at. While a single PDM is at, the full FS combined with several PDMs is designed
in such a way it is slightly concave as seen in gure 1.19 [21].
Figure 1.19: Construction scheme of the JEM-EUSO Focal Surface
Some other instruments, not used for the primary purpose, was also incorporated into the
design. A lidar (Light Radar) and IR-camera used for better measurements and atmospheric
models, as well as a protective lid and a tilting mechanism, [21, 22].
THE EUSO PROGRAM 17 of 68Hampus König Luleå University of Technology
Table 1.8: JEM-EUSO parameters
General Data
Status On hold
Mass 1153 kg
Dimensions (L W H) 2.97 m 3.35 m times 3.63 m
Shape/Size of lenses Circular, 2.5 m
Detector Hamamatsu R11265-M64
Number of detectors 4932
Number of Pixels 315648
Field of View 30°
Spatial Resolution 0.074°
Temporal Resolution 2.5 µm
1.10 POEMMA
Figure 1.20: POEMMA Overview and how it is intended to function
POEMMA (Probe of Extreme MultiMesenger Astrophysics) is the latest addition to the
EUSO-collaboration. The probe is not a fully EUSO project, but was selected in early 2017
under a Astrophysics Probe Mission Concept Study, ROSES-2016. During about 18 months,
a study is to be conducted which should de ne the instrument and mission among other
things. The study is being performed at GSFC (Goddard Space Flight Center) in USA and
is expected to be complete at the end of 2018. The study and several other studies for other
projects will be turned in to a Decadal Survey conducted by NASA, and the committee will
prioritize the proposed missions or recommend a line of probes.
The idea with POEMMA is as with most projects within the EUSO collaboration. To
investigate UHECR, and to use earth's atmosphere as a detector, while observing from space.
The dierences lies in how it is done. POEMMA is planned to have two detectors to give a
3-dimensional view of the EAS. The stereoscopic view idea, which is depicted in gure 1.20,
is adapted from the project OWL (Orbiting Wide angle Light concentrator), which is one
of the earliest projects with the intention of analysing CR.
Each of the separate satellites is planned to have a primary mirror somewhere around
4 m-10 m in diameter, and with corrective lenses on about 3.3 m-4.3 m in diameter. To the
right in gure 1.21a, showing a simulation of the optical design, the mirror is seen, while
18 of 68 THE EUSO PROGRAMLuleå University of Technology Hampus König
(a)
(b)
Figure 1.21: (a) shows a simulation of the optical design and (b) shows the layout of the
focal surface
the corrective lens is to the left in the same gure.
The focal surface is build with the components used for most projects in the EUSO-
collaboration, that is the PDM. However for this instrument, depending on the nal design,
it will have about 50-60 PDMs in the FS that will have a diameter between 1.6 m and 2.6 m,
and parts of the FS will consist of other sensors that will look for Cherenkov radiation
instead of uorescent light. They will be of a dierent kind of PMT, based on Silicon, so
called SiPM (Silicon Photo Multiplier). The planned layout of the FS is seen in gure 1.21,
where red is the SiPM sensors.
The temporal resolution will be 2.5 µs, but it could possibly be reduced even more, to
about 1 µs, with the SiPM detectors even faster, down to a temporal resolution of 100 ns.
Due to the case study not being complete, information regarding POEMMAs speci ca-
tion is not fully nalized. Speci cations are most likely bound to be changed the further the
project progress, but at this point, the ones speci ed are found in table 1.9 [23] [24] [25].
Table 1.9: POEMMA parameters
General Data
Status Case Study
Planned launch 2028+
Mass 1500 kg-2400 kg each
Shape/Size of Mirror Circular, 4 m-10 m
Shape/Size of lenses Circular, 3.3 m-4.3 m
Field of View 45°
Detector 1
Bialkali
Detector Hamamatsu R11265-M64
Temporal Resolution 1 µs-2.5 µs
Detector 2
SiPM
Detector SiMP
Temporal Resolution 100 ns
THE EUSO PROGRAM 19 of 68CHAPTER 2
Science objectives
The EUSO-collaborations rst goal to investigate was UHECR, but after time it was ex-
panded to cover several other areas. In this section, some information about the dierent
science missions the EUSO-collaboration have is found. For the scope of this thesis, the
main objective, Cosmic rays with high energies, as well as meteors and plastic detection,
will be looked at with some detail, while the other objectives will be mentioned.
2.1 Cosmic Rays
Cosmic rays are radiation that does not originate from the Earth, but instead from space.
UHECR are a subset of the cosmic radiation, and the name is due to its high energies. Some
authors state that energies above a value within the range 1 1017 eV to 1 1018 eV belongs
to UHECR [26, 27, 28]. An even more narrow subset of these particles belong to EHECR
(Extremly High Energy Cosmic Rays, sometimes mentioned as EECR) which some claims
to have energies above 1 1020 eV [28]. In comparison, the LHC (Large Hadron Collider)
about 7 10
12
accelerates particles to eV.
2.1.1 History and Background
The early 20th century had great progress within the eld of CR. In 1909, the German Jesuit
Priest and scientist, Theodor Wulf, improved the electroscope what he used to measure
radiation levels at various locations, with the Eiel tower being one [29, 30, 31]. His results
were almost as expected, and showed a lower value than at sea level, due to the idea that
the radiation came from the Earth's crust, but the rate of change was to small. He thought
there might be another source instead.
The Swiss physicist, Albert Gockel, followed with several balloon ights between 1909
and 1911, up to about 4500 m, and as T. Wulf discovered, the ionization of the air was lower
at a higher altitude. As previously this was expected, but the rate of change was to small
[29].
The scientist, Domenico Pacini, also made measurements with the electroscope between
1910 and 1914. The measurements were done at land, sea and under water, and he found
that the radiation under water was lover than on land, which should not be the case with
water's ability to shield from radiation if it originated from the Earth's crust. The conclusion
was that it exists some penetrating radiation in the atmosphere not originating from the
Earth [29].
It wasn't until the Austrian scientist Victor Hess made several balloon ights up to
5300 m between 1911 and 1912, that the existence of cosmic radiation was con rmed. By
ying three instruments during a solar eclipse, to rule out the suns contribution, he still
measured up to four times the radiation compared to ground level. He concluded "The
results of my observation are best explained by the assumption that a radiation of very
great penetrating power enters our atmosphere from above" [32] for which he received a
Nobel prize in 1936 [33].
The discovery of UHECR had to wait until the 1960's when John Linsley and Livio
Scarsi detected a particle with energies above 1 1020 eV. John Linsley concluded that the
nding was of great importance, since the region these particles could originate from was
not within our galaxy [34].
Later, even more energetic particles were found with one in 1991 that was recorded
with an energy of roughly 3.2 1020 eV. This particular event's particle was named the
"Oh-My-God particle" [35].
20 of 68 SCIENCE OBJECTIVESLuleå University of Technology Hampus König
2.1.2 Cosmic-Ray energies and ux
Figure 2.1: Energy spectrum of
cosmic rays [36]
Investigation of cosmic rays with high energy are very rare since it is di cult to even
detect it. One estimation is that about one particle over a century in every square kilometre
has energies above 1 1020 eV.
It is also di cult to detect the primary particle, and instead secondary particles, or
EAS, is used to calculate the primary particle's energy. This is shown in gure 2.1. The
spectrum seen in gure 2.1 is following the power law (dN dE { E γ ) well with energies below
2 10 6
GeV and have a value of γ 2.7.
However, at a couple of places, it bends, and they have been named the rst knee, second
knee and ankle (see gure 2.1). After the rst knee, which is placed at 2 106 GeV, gamma
changes to γ 3.1. At the second knee which are at about 4 10 GeV
8
it becomes even
steeper and at the ankle which is close to 4 109 GeV it recovers slightly.
The reason for the knees and ankle are debated. Some theories states that the knee is
due to the upper limitation of the acceleration of a galactic supernovae. Another theory is
that when the speed and energy increases in a proton within the galactic magnetic eld, the
Larmor radius becomes bigger than the thickness of the galactic disc [36].
2.1.3 GreisenZatsepinKuz'min limit
In gure 2.1 there is a cut o near the rightmost end of the graph shown. The physicist
Kenneth Greisen proposed that this was due to a theoretical upper limit of the energy
a particle (assumed proton in this case) can have. The limit is calculated from that it
would not exist any sources nearby that can produce particles with that amount of energies,
and that the protons from further away interacts with the CMB (Cosmological Microwave
Background) and thus slows down to under the limit [37].
Independently two other physicists made the same assumption, Georgiy Timofeyevich
Zatsepin and Vadim Alexeevich Kuz'min [38].
This lead to the GZK limit (GreisenZatsepinKuzmin limit) which in general means that
over a limit near 5 1019 eV, the occurrence of UHECR will quickly diminish, or disappear.
It is also possible to view the limit as a sphere with radius R 100 Mpc, and for particles to
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