Download Acronyme - LPSC

APPEL À PROJETS 2014
Project ANGELIC
DEFI DE TOUS LES SAVOIRS
ANGELIC
Auger New Generation ELectronics for Identification of Cosmic rays
1. SCIENTIFIC AND TECHNOLOGICAL OBJECTIVES
The Pierre Auger Observatory, the world largest cosmic ray experiment, is designed to
address Ultra High Energy Cosmic Rays physics, by observing the cascade of secondary
particles they produce (the Extensive Air Shower or EAS). The Observatory consists in a
large array of 1660 surface water-Cherenkov Detectors combined with 27 air fluorescence
telescopes. Measurements of the Auger Observatory have dramatically advanced our
understanding of Ultra High Energy Cosmic Rays. The suppression of the flux at the highest
energies is now confirmed without any doubt, and strong limits have been placed on the
photon and neutrino components. There are indications for a small, large-scale anisotropy
both below and above the energy of the ankle, and for a correlation on smaller angular scales
at E > 5.5 1019 eV. Particularly exciting, is the observed behavior of the depth of shower
maximum (Xmax) with energy, which changes in an unexpected, non-trivial way. Around
3.1018 eV it shows a distinct change of slope with energy, and the shower-to-shower variance
decreases. Interpreted with the leading LHC-tuned shower models, this implies a gradual
shift to heavier composition, and a number of fundamentally different astrophysical model
scenarios have been developed to describe this evolution. Precision measurements of shower
properties, strongly constrained by the hybrid data (events detected by the surface array and
the fluorescence detector), have revealed inconsistencies within present shower models,
opening also the possibility that the unexpected behavior is due to new hadronic interaction
physics at energy scales beyond the reach of LHC.
The data of the Pierre Auger Observatory are often considered as providing strong support
for classic models of UHECR sources. In these models it is typically assumed that particle
acceleration takes place at sites distributed similarly to the matter distribution in the universe
and the effect of energy loss processes (either pion-photoproduction or photo-disintegration)
causes the observed flux suppression at energies above 5 1019 eV, and some anisotropy of the
arrival direction distribution. Furthermore it is common to these models that mainly protons
are injected at extra-galactic sources with an energy spectrum following a power-law E- and
a maximum energy exceeding 1020 eV. The main differences of the models are related to the
assumptions on the index of the power-law and the mass composition at the sources. While
all models attribute the suppression of the energy spectrum to propagation effects, different
interpretations of the origin of the ankle are considered.
However, the measurements of the Pierre Auger Observatory have lead to a number of
puzzling observations that indicate a much more complex astrophysical scenario, which we
are far from understanding.
It is evident that this puzzle must be resolved in order to identify sources or source regions.
This has been the central goal of the Auger Observatory and indeed of all cosmic ray
research. The key lies in better identification of the primary composition, especially
extending to the highest energies.
1
APPEL À PROJETS 2014
Project ANGELIC
DEFI DE TOUS LES SAVOIRS
It is planned to operate the Pierre Auger Observatory until 2023. Relative to the data set
recorded until end of 2012, two times more statistics will be collected. But increasing the
statistics of the measured showers will not be sufficient to answer the key questions outlined
above. Therefore the Pierre Auger collaboration aims at an upgrade of the Observatory to
ensure that the data collected after 2016 will provide additional information to allow us to
address the following questions.
1. The primary objective of the upgrade of the Auger Observatory is to elucidate the
origin of the flux suppression and the mass composition at the highest energies, i.e.
the differentiation between the energy loss effect due to propagation and the
maximum energy of particles injected by astrophysical sources. This is a natural
evolution and major step forward from the original objective of the Pierre Auger
Observatory, which was motivated primarily by the question of the existence of a
GZK-like flux suppression. Understanding the origin of the flux suppression will
provide fundamental constraints on the astrophysical sources, including whether
these are predominantly of galactic or extragalactic nature, and will allow much more
reliable estimates of neutrino and gamma-ray fluxes at ultra-high energy for which we
will continue to search.
2. The search for a flux contribution of protons up to the highest energies will be the
second key science objective. We aim to reach sensitivity to a contribution as small as
10%. The measurement of the fraction of protons is the decisive ingredient for
estimating the physics potential of existing and future cosmic ray, neutrino, and
gamma-ray detectors. Prospects for proton astronomy with future detectors will be
determined. Moreover, the flux of secondary gamma rays and neutrinos due to proton
energy loss processes will be predicted.
3. Determining the mass composition of ultra-high energy cosmic rays is closely related
to, and crucially depends on, understanding extensive air showers and hadronic
interactions. Estimating the number of muons in air showers from Auger data, a
discrepancy between the observed and expected muon numbers is found. Therefore
the third key science objective will be the study of extensive air showers and hadronic
multiparticle production. This will include the exploration of fundamental particle
physics at energies beyond those accessible at man-made accelerators and the
derivation of constraints on new physics phenomena, such as Lorentz invariance
violation or extra dimensions.
To accomplish these science objectives it will be of central importance to improve the
composition sensitivity of the Auger Observatory and to extend it into the energy region of
the flux suppression.
Measurements of Xmax, the depth of the shower maximum, can presently be performed using
fluorescence detectors, only with a duty cycle of about 13%. Therefore the largest boost in
performance towards the aforementioned science goals is expected from an improved
composition sensitivity of the surface detector array. Such an improvement can be reached
by measuring, in addition to the total particle signal, the decomposition between
electromagnetic and muonic components at ground.
2
APPEL À PROJETS 2014
Project ANGELIC
DEFI DE TOUS LES SAVOIRS
Currently, information on the muonic component of the bulk of air showers is obtained
employing indirect methods, which lack desired precision and moreover require validation
through direct observation. Muons lead to characteristic peaks in the time trace of the surface
detectors, and their number can be estimated by subtracting the signal of the electromagnetic
shower component obtained from shower universality considerations or other means. Only
for sufficiently inclined showers or at large lateral distance from the shower core, can the
muon component be measured directly.
Composition-sensitive information can be obtained in the energy range of the flux
suppression by discriminating between the electromagnetic and muonic shower components
with upgraded detectors of the ground array. The determination of the number of muons of
a shower allows the separation of different mass groups of primaries at ultra-high energy.
Absolute calibration of the interpretation of the muonic signal will either come from
improved interaction models or a cross-calibration with Xmax data at lower energy. The eventby-event correlation between the depth of shower maximum and the muon number can be
used to disentangle different hadronic interaction scenarios. The determination of the
muonic shower component on an event-by-event basis will allow us to derive composition
discriminated fluxes in the range from about 1018 eV up to the highest energies, to carry out
composition-enhanced anisotropy searches based on event-by-event estimates of the primary
mass, to search for GZK secondaries and ultra-high energy photons produced in the
astrophysical environment of sources, and to test our understanding of hadronic interactions
at c.m.s. energies around and above 60 TeV.
To improve the composition measurement at the highest energies, the Auger Collaboration
proposes enhancing the electron/muon separation capabilities of the existing surface detector
stations. This will be accomplished either by adding dedicated scintillators or resistive plate
chambers, or by introducing a horizontal segmentation in the water Cherenkov tanks. Data
readout of the enhanced surface detector stations will be facilitated by replacing the current
readout electronics by modern state-of-the-art electronics providing three times faster
sampling, a significantly enhanced dynamic range (aided also by adding a small PMT in the
water-Cherenkov detectors), and enabling enhanced trigger and monitoring capabilities. We
consider this combination the fastest and most cost-effective way to obtain the required
composition information on shower-by-shower basis into the energy range of the fluxsuppression.
The proposed electronics upgrade provides a flexible interface to allow the muon upgrades
and other enhancements co-located with the surface detector stations to make use of the data
processing and communications infrastructure of the stations. In order to provide this
capability, a new processor with greater computing power is required. By using a processor
integrated in a field programmable gate array (FPGA), the details of the interface and its
protocols can easily be customized for the needs of both currently envisioned and future
enhancements.
The present proposal concerns this electronics upgrade, with the design of the new
generation of the main electronic board (UUB - Upgraded Unified Board), and the fabrication
3
APPEL À PROJETS 2014
Project ANGELIC
DEFI DE TOUS LES SAVOIRS
and test of several prototypes. This UUB is the key of this upgrade, with enhanced
capabilities but keeping the existing system interfaces. Its design should fulfill all the
specifications requested by the Auger collaboration, including science objectives
requirements. 15 UUB prototypes will be produced and tested before being deployed and
validated on site (engineering detector array).
2. RELEVANCE AND STRATEGIC CHARACTER OF THE PROJECT WITH
REGARD TO THE ORIENTATIONS OF THE CALL.
2.1. CONSISTENT WITH THE “DÉFI DE TOUS LES SAVOIRS”
The present funding request is submitted in the framework of the “Aux frontières de la
recherche” call for application, and is perfectly matching to the objectives of the component
“Défi de tous les savoirs”. Astroparticle Physics is a rapidly growing field of research at the
intersection of astrophysics, particle and nuclear physics and cosmology. Inside this field of
research, the scientific objectives of the Auger Observatory address in particular the
questions raised by the origin of cosmic rays and the view of the sky at extreme energies.
The Auger Surface Detector upgrades under investigation are focused on the need for better
identification and measurement of muons in the extended air showers. Combining this
information with other observables (such as the total signal in the water-Cherenkov detector,
or the electromagnetic component of the EAS, or the estimation of the depth of shower
maximum derived from accurate surface detector information), the nature of the ultra highenergy cosmic rays could be obtained on an event-by-event basis. The Pierre Auger
Observatory will be in a position to address high-energy astrophysics questions, and also to
understand the characteristics of the hadronic interactions at energy above those available to
current man-made accelerators.
The upgraded surface detector, with its embedded new electronics, could prefigure the
development of future cosmic ray detection arrays under discussion within the worldwide
community. One should also stress that the foreseen design of the new board and associated
electronics will be flexible enough to be used as a basis in any experiment where low
consumption, fast sampling frequency and local intelligence is needed for autonomous
detectors.
2.2. COLLABORATIVE PROJECT
The aim of the project is to design and realize prototypes of the new electronic board. To
perform such a development, it is necessary to joint effort between laboratories to benefit of
the skill from different teams. The development plan of the SDEU can be achieve only with a
strong collaborative effort of all the partners involved. The work packages include designs,
which are distributed through the French partners and the foreign institutes involved in the
Pierre Auger Collaboration. The collaborative effort of the partners is also driving the
activities of science simulation, on site deployment and final validation.
4
APPEL À PROJETS 2014
Project ANGELIC
DEFI DE TOUS LES SAVOIRS
3.
CONSORTIUM
• Partner’s description
The partner laboratories are all joint research units (UMR) of IN2P3/CNRS jointly with the
corresponding academic institutions. They are involved in multiple national and
international projects in the fields of particle physics, nuclear physics, observational
cosmology and astroparticle physics. Furthermore, the partner teams are already working
closely together within the Pierre Auger Collaboration. All the three laboratories have a very
high level technical expertise in developing detectors mechanics and electronics as well as in
computing science.
Partner 1: IPNO
The “Institut de Physique Nucléaire d’Orsay” entered the Auger Collaboration in 2000,
taking the head of the Electronics of the Surface Detector task. The IPNO group was in
charge of the construction and deployment of the PMT electronics for the 1670 tanks already
deployed successfully installed in Argentina. In addition, members of the IPNO have been in
charge of the commissioning of the Auger Surface detector, and they have been also working
for the development of the central data acquisition system. They also developed the tools for
the evaluation of the acceptance of the surface array.
IPNO Scientists involved in the project: T. Suomijarvi (Scientific coordinator)…
Partner2 : LPSC
The partner team from the “Laboratoire de Physique Subatomique et de Cosmologie” of
Grenoble has acquired during the last decade a solid know-how on detection techniques of
ultra high energy cosmic rays (UHECR). In the framework of the EUSO (Extreme Universe
Space Observatory) project, between 2001 and 2005, the group activities concerned in
particular the front-end electronics design. In 2006, the group joined the Pierre Auger
Collaboration, and worked on photo-detectors maintenance, surface detector monitoring,
software simulation and analysis, in particular to search for high energy cosmic neutrinos.
The team is also involved in R&D for UHECR radio detection.
The corresponding team will benefit from a very strong support from the LPSC technical
departments with a very high level of technical expertise in developing detectors mechanics
and electronics as well as in computing science.
LPSC Scientists involved in the project: C. Berat, D. Lebrun, F. Montanet, A. Stutz
Partner3 : LPNHE
The “Laboratoire de Physique Nucléaire et des Hautes Énergies” is one of the founding
members of the Auger Collaboration. Between 1992 and 1998 before the approval of the
Auger project in France, members of this laboratory contributed to the observatory site
evaluation and selection, to the design report editing (including the innovative hybrid design
adopted by Auger and which has proven its excellent performances), and to the construction
of a solid French cosmic ray community that finally led to the French funding of the Auger
project in 1998. Since then, LPNHE has developed the central data acquisition system
including the central triggering and monitoring of the observatory.
LPNHE Scientists involved in the project:
5
APPEL À PROJETS 2014
Project ANGELIC
DEFI DE TOUS LES SAVOIRS
Partner4 : Subatech (? To be confirmed)
• Qualification of the Project Coordinator
To be done
• References
Contributions to the 33rd International Cosmic Ray Conference, the Pierre Auger
Collaboration, ICRC 2013, Rio de Janeiro, Brazil, http://arxiv.org/abs/1307.5059 (2013)
6