University of Bucharest [604357]

University of Bucharest
PhD Thesis
Advanced detection systems for
cosmic rays investigation
Author:
Alexandru BalaceanuSupervisors:
Acad. Prof. Dr. Nicolae
Victor ZAMFIR
This thesis fulls the requirements for the degree of PhD of Physics
Faculty, Bucharest University
It was carried out in
Nuclear Physics Department
of the National Institute for Physics and Nuclear
Engineering-Horia Hulubei, Bucharest, Romania

Declarat ie
Subsemnatul Alexandru B al aceanu, declar pe propria r aspundere c a lucrarea de
fat  a este rezultatul muncii mele, pe baza cercet arilor mele  si pe baza informat iilor
obt inute din surse care au fost citate  si indicate, conform normelor etice, ^ n note
 si ^ n bibliograe. Declar c a nu am folosit ^ n mod tacit sau ilegal munca altora
si c a nici o parte din tez a nu ^ ncalc a drepturile de proprietate intelectual a ale
altcuiva, persoan a zic a sau juridic a. Declar c a lucrarea nu a mai fost prezentat a
sub aceast a form a vreunei alte institut ii de ^ nv at  am^ ant ^ n vederea obt inerii unui
grad sau titlu  stiint ic ori didactic.
Semn atura candidat: [anonimizat] :
Data:
Semn aturile conducatorilor lucr arii :
ii

UNIVERSITY OF BUCHAREST
Abstract
Faculty of Physics
Nuclear Physics Department
PhD
Advanced detection systems for cosmic rays investigation
by Alexandru Balaceanu

Acknowledgements
iv

Contents
Declaration of Authorship ii
Abstract iii
Acknowledgements iv
1 Outlook: the WILLI-AUGER detector 1
2 Conclusions 5
List of Figures 7
A Abbreviations 9
Bibliography 11
v

Chapter 1
Outlook: the WILLI-AUGER
detector
Multiple techniques were developed to investigate the EAS at the ground level,
used with success in numerous experiments, like KASCADE-Grande, AGASA,
LOPES, LOFAR, the most complex of them being The Pierre Auger Observatory
[70].
Located in Mendoza, Argentina, covering an area of 3000 km2, Pierre Auger Obser-
vatory is a giant hybrid array of particle detectors, using several dierent detection
systems to reconstruct the information regarding the primary cosmic particles [71],
like energy or mass [72], in order to search for sources of ultra-high energy cosmic
rays [73], [74], and neutrinos [75], [76], [77].
The experiment layout can be seen in Figure 1.2. To detect shower particles
that reach the ground, 1660 water Cherenkov Surface Detectors are deployed
over 3000 km2area [78],[9] , 27 telescopes grouped in 4 locations(Loma Amar-
illa, Coihueco, Los Leones and Los Morados ) that represent the Fluorescence
Detectors (FD) [79] and the extension HEAT, together with 153 radio antennas
that form the Auger Engineering Radio Array (AERA)[80].
Several Romanian research institutes and universities, IFIN-HH, UB, UPB, ISS,
grouped in AUGER-RO Consortium, are part of the Pierre Auger collaboration,
being involved in the assigned tasks and activities with resources and manpower
in order for the experiment to address the studied topics and full the objectives
it was designed for.
1

Chapter 5. The WILLI-AUGER detector 2
Figure 1.1: Map view for the AUGER experiment.
Excepting the involvement in solving the assigned tasks by the collaboration, like
monitoring AERA stations functionality, participating in Fluorescence Detectors
(FD) data taking procedure (FD shifts), building spare parts for AERA experiment
or participating in AERA data acquisition (AERA shift), I am also contributing
to the current work.
The Pierre Auger Observatory continues to develop with the Auger Prime upgrade,
which include 4 km2plastic scintillator detectors, called Surface Scintillator Detec-
tor stations (SSD), installed on top of all 1660 water-Cherenkov tanks for a better
determination of the muon component of air showers and the Auger Muons and
Inll for the Ground Array (AMIGA), under construction, designed to investigate
the transition from extragalactic to galactic cosmic rays[81], [82], [83].
AMIGA [84] consists of buried scintillator detectors used for muon counting in co-
incidence with an inll array of surface water-Cherenkov detectors that measures
EAS produced by primaries in the energy range 1017eV- 1018eV. The main objec-
tives of AMIGA are to measure the composition-sensitive observables of extensive
air showers and to study features of the hadronic interactions. The observables
measured by AMIGA includes energy, atmospheric depth at shower maximum

Chapter 5. The WILLI-AUGER detector 3
Xmax ;EM, the number of muons at an optimal lateral distance from the shower
axisNopt, muon production depth Xmax ;. The upgrade was strongly motivated by
the need for measurements that will allow us to address questions like the mass
composition and the origin of the
ux suppression at the highest energies, or the
test of most up-to-date particle-physics models because The Pierre Auger Obser-
vatory has already detected more muons from cosmic-ray showers than predicted
from models using LHC data as input [85].
Because of the large number of detectors that had to be deployed, the design was
restricted to a single layer of plastic scintillator, making it very sensible to elec-
tronic noise and background radiation (i.e. from the volcanic soil in the Pampa).
A reliable calibration tool is needed to determine the proper functionality param-
eters and also correctly estimate and to minimize the systematic muon-number
counting uncertainties stemming from mechanical design.
Due to the experience in building muon detectors using advanced technology, IFIN-
HH received the task from the Pierre Auger Collaboration to build a muon detector
able to measure the angular muon
ux, meant to measure in coincidence with the
AMIGA and SSD detectors.
In order to perform the task, taking into account the scientic, mobility and cost
requirements, several congurations for a directional muon
ux tracking detector
were designed, based on previous experience with WILLI calorimeter, SiRO detec-
tor [86] or NEMO [brevet + articol] I am also involved in this detector construction
for the AUGER experiment.
It was decided that the best conguration is to be composed of 6 active layers 
1m2each and read-out just on one end, or to have 4 active layers read-out at both
ends. The last scenario bring the improvement in signal to noise ratio(using the
condition of having signals at each end of the strip) and a great improvement in
position resolution. By making the time dierence between the ends of the plastic
strip the position of the hit can be calculated. The better position is helpful for
the trajectories reconstruction.
Each layer being divided in 40 plastic scintillator bars. The scintillation signals
being transported through optical bres to optical sensors. The layers are grouped
two by two, with the length of the scintillator bars perpendicularly placed, in
order for the trajectory of the incident muons to be reconstructed. The CAD
drawing for the detector arrangement and mechanical support can be seen in

Chapter 5. The WILLI-AUGER detector 4
Figure 1.2: CAD view for the mechanical support of the 4 layers WILLI
calorimeter proposal for the AUGER collaboration.
Figure 1.2. Dierent aspects of the selected optical mounting, optical sensors,
Front End Electronics (FEE) and DAQ are currently being tested. For the optical
sensors two dierent technologies are tested to be utilised for the detection system,
such as clasical PMT and Silicon Photomultiplier(SiPM). The main issue can
be represented by the weather, on the classical PMT side the main problem is
represented by the power consumption, on winter time the solar pannel can have
diculties sustaining the power. On the SIPM side the temperature variation
form 40Cfor the summer to -20Cfor the winter can represent a diculty. Both
techniques are tested in our laborratory and the best solution will be utilised for
the presented detector.
This detector represents a key element for the mass reconstruction and interaction
models testing that will be performed after the AugerPrime upgrade. Its integra-
tion in the Oine framework and its correlation with AMIGA buried detectors
and SSD stations being extremely important for its good use in the Pierre Auger
framework.

Chapter 2
Conclusions
The WILLI-AIR (Weal Ionization Lead Lepton Interaction for Air-shower Inves-
tigations in Romania) experiment is developed to investigate charged particle re-
sulted in the interaction in the external layers of the atmosphere of cosmic particles
with nuclei. The experiment is focused on the charged particles that arriving at
the ground level and produced by primary particles with their energy around the
value of 1015eV.
A measurement system WILLI-AIR was developed and measure the muon charge
ratio in individual showers. The detection basis is to measure in correspondence
the shower parameters with the array and muon charge ratio with WILLI calorime-
ter. Based on simulations and taking into account the local infrastructure con-
guration around WILLI, the optimum arrangement of the array was achieved.
The system is now functional and currently recording data from the extended air
showers.
A short description for the new integrated and ultra fast electronics is brie
y
presented.The upgrade of the front-end electronics was mandatory because of the
old one was fairly obsolete and also some of the components were showing aging
eects. The projects are designed in our group, of course with the help from the
experts from KIT but more important also from our institute. The CAD drawings
for the raw designs are brie
y presented.
Detailed tests were performed using the new PCB's. These test were mainly
focused to determinate the boards capabilities and functionalities.
5

Chapter 6. Conclusions 6
There are two main aspects regarding this work. The main purpose is to deliver
some measured data in the low energy range for cosmic muons. In a certain region
of the cosmic rays spectrum, were it is still more to be solved. Any kind of data are
important for the scientic community and in our case it is a measurement waited
for a long time. The muon charge ratio is a data measured in the last decades
by many people, but the correlation between the number of muons(positive and
negative ones) inside an air shower cascade, at the low energy region for cosmic
ray spectrum is a value that still has to be determinate.
Second aspect of this work is focused on the hardware development. The process
of testing many dierent scenarios and dierent schematics is time consuming but
is delivering real solutions and real understanding of the detectors, front-end and
DAQ systems. Further these hardware can be extended to dierent experiments
and also to dierent detections techniques. By developing the technique all the
time and also keeping the laboratory tools up to date is a huge step forward in
order to be in line with the best scientic people in the world. As presented in
Chapter 5 our group experience is utilised to build a complete muon detection
system, to be sent at the Pierre Auger experiment.
By understanding the process involved in R&D activities on front-end electron-
ics, these technique can be extended to dierent detectors applications. Further,
these activities can represent a focus to a research direction for our team, wich is
represented by a condensed group of young people.

List of Figures
1.1 Map view for the AUGER experiment. . . . . . . . . . . . . . . . . 2
1.2 CAD view for the mechanical support of the 4 layers WILLI calorime-
ter proposal for the AUGER collaboration. . . . . . . . . . . . . . . 4
7

Appendix A
Abbreviations
EAS Extended Air Shower
ADC Amplitude-to-digital converter. Measures the maximum amplitude
of detector signals during a gate.
CFD Constant fraction discriminator.
DAQ Digital acquisition system.
NIM Nuclear Instrument Module.
Scaler Counts the number of pulses.
TDC Time-to-digital converter.
TOF Time-of-
ight.
VME VERSA module eurocard, a databus, commonly used in industry
for computing and control applications.
9

Bibliography
[1]V.F. Hess (1936). "Unsolved Problems in Physics: Tasks for the Immedi-
ate Future in Cosmic Ray Studies". Nobel Lectures. The Nobel Foundation.
Retrieved 2010-02-11.
[2] A. Haungs, H. Rebel and M. Roth. Energy spectrum and mass composition
of high-energy cosmic rays. Rep. Prog. Phys. , 66:1145{1206, 2003.
[3] A. D. Panov et al. The energy spectra of heavy nuclei measured by the atic
experiment. Advances in Space Research , 37:1944{1949, 2006.
[4] A. D. Panov et al. The energy spectra of heavy nuclei measured by the atic
experiment. Advances in Space Research , 37:1944{1949, 2006.
[5] I. V. Galkin et al. For the RUNJOB Collaboration. High-energy gamma
rays in the runjob experiment. Bulletin of the Russian Academy of Sci-
ences: Physics , 71(4):491{493, Apr 2007. ISSN 1934-9432. doi: 10.3103/
S1062873807040156.
[6] J. Blumer, Ralph Engel and Jorg Horandel. Cosmic rays from the knee to the
highest energies. Progress in particle and Nuclear Physics , 63:293{338, 2009.
[7] J.R. Hrandel. Models of the knee in the energy spectrum of cosmic rays.
Astroparticule Physics , 21:241265, 2004.
[8] K.-H. Kampert. Ultra high-energy cosmic ray observations. Journal of
Physics , Conference Series, 2008.
11

Bibliography 12
[9] A. Aab et al. for the Pierre Auger Collaboration. Inferences on mass compo-
sition and tests of hadronic interactions from 0.3 to 100 eev using the water-
cherenkov detectors of the pierre auger observatory. PHYSICAL REVIEW
D, 96(12), DEC 8 2017. ISSN 2470-0010. doi: 10.1103/PhysRevD.96.122003.
[10] A. Aab et al. Muons in air showers at the pierre auger observatory: Mean
number in highly inclined events. Phys. Rev. D , 91:032003, 2015. doi: 10.
1103/PhysRevD.91.032003.
[11] H. Rebel and O. Sima. Information about high-energy hadronic interaction
processes from extensive air showers observations. Rom. Journ. Phys , 57:
472{492, 2012.
[12] A. Aab et al. for the Pierre Auger Collaboration. Azimuthal asymmetry in
the risetime of the surface detector signals of the pierre auger observatory.
Phys. Rev. D , 93(122005), 2016. doi: 10.1103/PhysRevD.93.072006.
[13] et al. B. Mitrica. A mobile detector for measurements of the atmospheric
muon
ux in underground sites. Nucl. Inst and Meth. A , 654:176{183, 2011.
[14] Wentz, J and Bercuci, A and Heck, D and Mathes, H and Oehlschlaeger, J
and Rebel, Heinigerd and Vulpescu, B. Simulation of atmospheric neutrino

uxes with corsika. 3:1167, 07 2001.
[15] Paolo Lipari. The
uxes of subcuto particles detected by ams, the cosmic
ray albedo and atmospheric neutrinos. 1:1599, 01 2001.
[16] M. Honda and T. Kajaita. New calculation of the atmospheric neutrino
ux
in a 3-dimensional scheme. astro-ph , 4:404{457, 2004.
[17] Halil Arslan and Mehmet Bektasoglu. Altitude prole of atmospheric muons
in a location with relatively high cut-o rigidity. Advances in Space Research ,
56, Issue 11:2662{2668, 2015.
[18] B. Mitrica et al. A mobile detector for muon measurements based on two
dierent techniques. Hindawi Publishing Corporation , page 256230, 2013.

Bibliography 13
[19] et al. D. Stanca. Measurements of the atmospheric muon
ux using a mobile
detector based on plastic scintillators read-out by optical bers and pmts.
JPCS , 409:012136, 2013.
[20] et al. B. Mitrica. A mobile detector for muon measurements based on two
dierent techniques. ADV HIGH ENERGY PHYS , page 256230, 2013.
[21] L. W. Alvarez et al. Testing hadronic interactions at ultrahigh energies with
air showers measured by the pierre auger observatory. Science 167 , 1970.
[22] K Morishima et al. Discovery of a big void in khufu's pyramid by observation
of cosmic-ray muons. Nature , (552), 2017.
[23] K Morishima et al. A muon detector to be installed at the pyramid of the
sun. Rev. Mex. Fis , 49, 2003.
[24] K Nagamine et al. Method of probing inner-structure of geophysical substance
with the horizontal cosmic-ray muons and possible application to volcanic
eruption prediction. Nucl Instrum Methods Phys Res A , 356, 1995.
[25] G. G. Barnafoldi et al. Portable cosmic muon telescope for environmental
applications. Nucl Instrum Methods Phys Res A , 689, 2012.
[26] B. Mitrica et al. Muography aplications developed by in-hh. Philosophical
Transcations of the Royal Society A , 2018.
[27] W.d.apel et al. kascade-grande collaboration, nucl. instr. meth. a 620 (2010)
202-216.
[28] J.abraham et al. auger collaboration, nucl. instr. meth. a 523 (2004) 50-95.
[29] B. Vulpescu et al. A compact detector for the measurement of the cosmic-ray
muon charge ratio. Nuclear Instruments and Methods in Physics Research A ,
414:205{217, 1998.
[30] TR. K. Adair, H. Kasha, R. G. Kellogg, L. B. Leipuner, and R. C. Larsen.
Determination of the neutron-proton ratio in primary cosmic rays. Physical
Review Letter , 39:112, 1977.

Bibliography 14
[31] G. BARDIN, J. DUCLOS, A. MAGNON, J. MARTINO. A new measurement
of the positive muon lifetime. PHYSICS LETTERS , 137B:6, 1984.
[32] H. Rebel et. Al. The muon charge ratio in cosmic ray air showers.
arXiv:0806.4739v1 , 2008.
[33] T. Suzuki and D.F. Measday. Total nuclear capture rates for negative muons.
Physical Review C , 35, 1987.
[34] B. Vulpescu et al. The charge ratio of atmospheric muons below 1.0 gev/c
by measuring the lifetime of muonic atoms in aluminium. J Phys. G: Nucl.
Part. Phys.
[35] B. Vulpescu. PhD thesis . PhD thesis, 1999.
[36] Iliana M. Brancus et al. The east-west eect of the muon charge ratio at en-
ergies relevant to the atmospheric neutrino anomaly. Nuclear Physics , A721:
1044c{1047c, 2003.
[37] I.M. Brancus. Proc. isvhecri, weihei, china, 2006.
[38] Mitrica, B. and Brancus, I. M. and Toma, G. and Wentz, J. and Rebel, H. and
Bercuci, A. and Aiftimiei, C. Experimentally guided monte carlo calculations
of the atmospheric muon
ux for interdisciplinary applications. Rom. Rep.
Phys. , 56:733{740, 2004.
[39] B. Mitrica et al. Experimentally guided monte carlo calculations of the at-
mospheric muon. Nuclear Physics B , 151:295{298, 2006.
[40] et al. S. Tsuji. Nucl. Instr. and Methods in Phys. Res. , A 413:43{49, 1998.
[41] Bogdan Mitrica. Studies of the directional dependence of the muon
ux and
possibilities to test the hadronic interaction models . PhD thesis, Department
of Nuclear Physics, Faculty of Physics University of Bucharest, Romania,
2010.
[42] R.J.R.Judge and W.F.Nash. Il Nuovo Cimento , XXXV-4:999, 1965.

Bibliography 15
[43] B. Mitrica, et al. Internal report kaskade-grande, forschungszentrum karl-
sruhe. pages 2004{01, 2004.
[44] H. Rebel, et al. Scientic report on the nato project nr. pdd(cp)-(pst.clg
979737). 2004.
[45] et al. H. Bozdog. Nucl. Instr. and Meth. , A 465:244, 2001.
[46] O. Sima, I.M. Brancus, H. Rebel, A. Haungs. Showrec- a program for recon-
struction of eas observables from kaskade-grande observations. FZKA 6985 ,
2004.
[47] Denis Iulian STanca. Studies of cosmic ray muons using compact scintillator
detectors . PhD thesis, Department of Nuclear Physics, Faculty of Physics
University of Bucharest, Romania, 2012.
[48] B. Mitrica et al. A mobile detector for muon measurements based on two
dierent techniques. Hindawi Publishing Corporation , page 256230, 2013.
[49] H. Rebel et. Al. The muon charge ratio in cosmic ray air showers. FZKA
7294, 2007.
[50] http://www.caen.it/csite/caenprod, .
[51] R. Barth. GSI Multi-Branch System User Manual . GSI, Gesellschaft fur Schw-
erionenforschung mbH Planckstrae 1, D-64291 Darmstadt Germany, Jan-
uary14,2000.
[52] Creative electronics systems-http://www.ces-swap.com/single-board-
computers/.
[53] S. Agostinelli et al. Geant4 – a simulation toolkit. Nucl. Instr. Meth. A , 506:
250{303, 2003.
[54] A. Balaceanu, et al. Hardware development for the weak ionization lead lepton
interaction for air-shower investigations in romania- willi-air experiment. AIP
Conference Proceedings , 1852(1), 30 June 2017.

Bibliography 16
[55] Eagle software. URL http://www.autodesk.com/products/eagle/
free-download .
[56] Ethernet cat 6a cable. URL http://www.en.m.wikipedia.org/wiki/
Category_6_cable .
[57] A. Balaceanu, Master thesis. "towards a real size rpc prototype for the time
of
ight inner zone of cbm experiment at fair. 30 June 2014.
[58] F. Anghionol, P. Jarron, A.N. Martemiyanov, E. Usenko, H. Wenninger,
M.C.S. Williams, A. Zichichi . Nino: an ultra-fast and low-power front-end
amplier/discriminator asic designed for the multigap resistive plate chamber.
Nuclear Instruments and Methods in Physics Research . , A 533:183{187, 2004.
[59] F Anghinol, P Jarron, F Krummenacher, Evgeny Usenko, and Crispin
Williams. Nino, an ultra-fast, low-power, front-end amplier discriminator
for the time-of-
ight detector in alice experiment. 1:375 { 379 Vol.1, 11 2003.
[60] Lvds standard. URL http://www.en.m.wikipedia.org/wiki/
Low-voltage-differential-signal .
[61] altium designer, http://www.altium.com/altium-designer/overview.
[62] URL https://www.gsi.de/work/forschung/experimentelektronik/
digitalelektronik/digitalelektronik/module/trigger_
synchronisation/triva/triva7.htm .
[63] URL https://www.gsi.de/en/work/research/experiment_electronics/
digital_electronic/digital_electronics/modules/vme/vulom/
vulom4b.htm .
[64] CAEN ADC V785 32ch user manual, . URL http://www.caen.it/csite/
CaenProd.jsp?idmod=37&parent=11 .
[65] CAEN TDC V1290N 32ch user manual, . URL http://www.caen.it/csite/
CaenProd.jsp?idmod=789&parent=11 .

Bibliography 17
[66] I. Brancus et al. Willi-eas, a detector for observing atmospheric and eas
muons. 32nd International Cosmic Ray Conference, Beijing , 4:22{25, 2011.
[67] R. Brun and F. Rademakers. An object-oriented data analysys framework,
nucl. instr. and meth., 81, 398, 1997.
[68] J. Adamczewski et al. Distributed object monitoring for root analyses with
go4 v3. IEEE TNS , 565:51, 2004.
[69] A. Balaceanu, et al. Cosmic ray measurements using willi-air setup. ROMA-
NIAN REPORTS IN PHYSICS , 2018.
[70] A. Aab et al for the Pierre Auger Collaboration. Search for ultrarelativistic
magnetic monopoles with the pierre auger observatory. PHYSICAL REVIEW
D, 94(8), OCT 3 2016. ISSN 2470-0010. doi: 10.1103/PhysRevD.94.082002.
[71] A. Aab et al. for the Pierre Auger Collaboration. Observation of a large-
scale anisotropy in the arrival directions of cosmic rays above 8 x 1018ev.
SCIENCE , 357(6357):1266{1270, 2017. ISSN 0036-8075. doi: 10.1126/science.
aan4338.
[72] A. Aab et al. for the Pierre Auger Collaboration. Evidence for a mixed mass
composition at the `ankle' in the cosmic-ray spectrum. PHYSICS LETTERS
B, 762:288{295, 2016. ISSN 0370-2693. doi: 10.1016/j.physletb.2016.09.039.
[73] A. Aab et al. for the Pierre Auger Collaboration. An indication of anisotropy
in arrival directions of ultra-high-energy cosmic rays through comparison
to the
ux pattern of extragalactic gamma-ray sources. ASTROPHYSI-
CAL JOURNAL LETTERS , 853(2), 2018. ISSN 2041-8205. doi: 10.3847/
2041-8213/aaa66d.
[74] A. Aab et al. for the Pierre Auger Collaboration. Multi-resolution anisotropy
studies of ultrahigh-energy cosmic rays detected at the pierre auger observa-
tory. JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS ,
(6), JUN 2017. ISSN 1475-7516. doi: 10.1088/1475-7516/2017/06/026.

Bibliography 18
[75] A. Albert et al. for ANTARES Collaboration, IceCube Collaboration,
Pierre Auger Collaboration, LIGO Sci Collaboration, and Virgo. Search
for high-energy neutrinos from binary neutron star merger gw170817 with
antares, icecube, and the pierre auger observatory. ASTROPHYSICAL
JOURNAL LETTERS , 850(2), DEC 1 2017. ISSN 2041-8205. doi: 10.3847/
2041-8213/aa9aed.
[76] B. Abbott et al. Multi-messenger observations of a binary neutron star
merger. ASTROPHYSICAL JOURNAL LETTERS , 848(2), OCT 20 2017.
ISSN 2041-8205. doi: 10.3847/2041-8213/aa91c9.
[77] A. Aab et al. for the Pierre Auger Collaboration. Ultrahigh-energy neutrino
follow-up of gravitational wave events gw150914 and gw151226 with the pierre
auger observatory. PHYSICAL REVIEW D , 94(12), 2016. ISSN 2470-0010.
doi: 10.1103/PhysRevD.94.122007.
[78] A. Aab et al. for the Pierre Auger Collaboration. Impact of atmospheric eects
on the energy reconstruction of air showers observed by the surface detectors
of the pierre auger observatory. JOURNAL OF INSTRUMENTATION , 12,
2017. ISSN 1748-0221. doi: 10.1088/1748-0221/12/02/P02006.
[79] A. Aab et al. for the Pierre Auger Collaboration. Spectral calibration of
the
uorescence telescopes of the pierre auger observatory. ASTROPAR-
TICLE PHYSICS , 95:44{56, OCT 2017. ISSN 0927-6505. doi: 10.1016/j.
astropartphys.2017.09.001.
[80] A. Aab at al. for the Pierre Auger Collaboration. Calibration of the
logarithmic-periodic dipole antenna (lpda) radio stations at the pierre auger
observatory using an octocopter. JOURNAL OF INSTRUMENTATION , 12,
OCT 2017. ISSN 1748-0221. doi: 10.1088/1748-0221/12/10/T10005.
[81] A. Aab et al. for the Pierre Auger Collaboration. Combined t of spectrum
and composition data as measured by the pierre auger observatory (vol 4, 038,
2017). JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS ,
(3), 2018. ISSN 1475-7516. doi: 10.1088/1475-7516/2018/03/E02.

Bibliography 19
[82] A. Aab et al. for the Pierre Auger Collaboration. Search for photons with
energies above 10(18) ev using the hybrid detector of the pierre auger obser-
vatory. JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS ,
(4), 2017. ISSN 1475-7516. doi: 10.1088/1475-7516/2017/04/009.
[83] A. Aab et al.for the Pierre Auger Collaboration. Combined t of spectrum and
composition data as measured by the pierre auger observatory. JOURNAL OF
COSMOLOGY AND ASTROPARTICLE PHYSICS , (4), APR 2017. ISSN
1475-7516. doi: 10.1088/1475-7516/2017/04/038.
[84] A. Aab et al. for the Pierre Auger collaboration. Muon counting using sil-
icon photomultipliers in the amiga detector of the pierre auger observatory.
JOURNAL OF INSTRUMENTATION , 12, MAR 2017. ISSN 1748-0221. doi:
10.1088/1748-0221/12/03/P03002.
[85] A. Aab et al. for the Pierre Auger Collaboration. Testing hadronic inter-
actions at ultrahigh energies with air showers measured by the pierre auger
observatory. Phys. Rev. Lett. , (192001), 2016.
[86] D. Stanca, et al. A feasibility study to track cosmic muons using a detector
with SIPM devices based on amplitude discrimination. ROMANIAN RE-
PORTS IN PHYSICS , 69(301), 2017.