Physics at the Large Hadron Collider (LHC) at CERN (European Organization for Nuclear Research) is the high priority research field of the Particle Physics community worldwide. ATLAS is one of the two general purpose experiments installed at the LHC that discovered a Higgs boson in July 2012, key piece for the understanding of the fundamental interactions and the origin of elementary particle mass. Its physics program extends beyond Higgs property measurements to the search for signs of physics beyond the Standard Model of particle physics.
The ATLAS group of the Centre de Physique des Particules de Marseille (CPPM) is deeply involved in this scientific program, in particular linked to its expertise of the electromagnetic calorimeter. The latter is a key component for the identification and energy measurement of electrons and photons, which were at the core of the Higgs boson discovery. It is also at the forefront of this boson studies and of the supersymmetry searches in the ongoing data taking campaign, so called Run 2, with major consequences in several analyses with leptons in their final states. Moreover, for the upgrade of the accelerator performances foreseen in 2021, this calorimeter has a major ongoing development program to dramatically upgrade its trigger and readout to which the CPPM group actively contributes.
In the Standard Model, the Higgs boson is highly coupled to the top quark, the known particle with the largest mass. The only way to directly measure this Higgs-top coupling (called top Yukawa coupling) is to observe the associated production of a Higgs boson with top quarks. This will be accessible for the first time with the Run 2 data taken between 2015 and 2018 from LHC proton-proton collision at a 13 TeV center of mass energy. This key measurement, and more generally the Higgs properties studies are of high importance since they would allow to confirm that the observed boson is the Standard Model Higgs boson, or could reveal New Physics.
The subject of this M2 internship is to participate in the measurement of the properties of the Higgs boson in the final states with several leptons (electrons or muons) in particular by relying on multivariate analysis tools. These studies will be done on the Run 2 data set. This should lead, by summer 2019, to get the best sensitivity on some of the Higgs properties in particular its Yukawa coupling. Furthermore, depending on the interests of the student, participation in the study of a prototype installed on the detector in early 2018 as part of the electromagnetic calorimeter upgrade program is also possible.
In this framework, the student may have to go to CERN and the research work will combine physics analysis on real and simulated data as well as studies and operation of experimental systems. This internship can naturally then evolve to a thesis
Le cadre de ce stage est l'expérience H.E.S.S. (https://www.mpi-hd.mpg.de/hfm/HESS) et la recherche d'émission de gammas d'énergie > 30 GeV par des systèmes binaires galactiques comprenant un trou noir ou une étoile à neutrons, et possédant des jets résolus en radio (dénommés microquasars). A l'heure actuelle seul Cygnus-X1 a montré une émission de ce type, à 4.1 sigmas seulement, mesurée par l'expérience MAGIC. Durant le stage une approche multi-longueur d'onde de trois objets sera à mener : GRS 1716-249, MAXI J1535-571, et MAXI J1820+070. Ces trois systèmes binaires, tous des Low Mass X-ray Binaries (LMXB, c'est à dire étoile compagnon de basse masse) ont été observés par H.E.S.S. en avril 2017, septembre 2017, et plusieurs fois durant l'année 2018, respectivement. En plus de l'analyse des données H.E.S.S., l'étudiant devra réunir et analyser les données d'observation publiques sur chacun de ces objets en X (MAXI, Swift, NICER, Integral), radio, gamma HE (Fermi). En particulier, en rayons X, pour lesquels l'observation est positive, des diagrammes observationnels spécifiques (Hardness-Intensity Diagrams) seront à construire, tel que dans http://www.astronomerstelegram.org/?read=12068, caractérisant les différents régimes d'émission X. Leur interprétation en termes de phénomènes physiques sous-jacents sera à mener sur des bases bibliographiques, pour y déterminer le contexte de l'observation menée par H.E.S.S. De même, une mesure du flux de gamma HE (données publiques Fermi/LAT) sera à mener : une première étape étant une mesure de type photométrie d'ouverture, l'étape suivante étant une mesure basée sur un maximum de vraisemblance signal/fond. Le stage dure 4 mois, en 2019, et peut éventuellement déboucher sur une thèse. Un exemple de publication réalisée sur le sujet (pour 3 autres objets) est disponible ici : https://arxiv.org/abs/1607.04613
The KM3NeT Collaboration will instrument two deep-sea neutrino detectors in the Mediterranean Sea, a low energy site ORCA in France (5 GeV-10 TeV) and a high energy site ARCA in Italy (1 TeV-10 PeV). Both detectors will have a sensitivity largely improved compared to ANTARES at low and high energies. CPPM is the host lab of KM3NeT/ORCA and has therefore a privileged position in the Collaboration. Beginning of 2019, 6 ORCA and 2 ARCA lines should be in operation.
There is a good science case at medium energies (100 GeV - 10 TeV) where we may expect neutrino signals coming from colliding winds of galactic binary systems, obscured extra-galactic sources (AGN, GRB). The main goal of this intern-ship is to compute the high-energy performances of ORCA (above 100 GeV) using dedicated Monte Carlo simulations. Using this study, the student will be able to compute the minimal flux for specific astrophysical sources to be detect by KM3NeT/ORCA and compare the expectation with the first few months KM3NeT data.
The analyses will be performed using C++, python and Root on Linux platforms. Some knowledge in C/C++/python language is welcomed.
This subject is linked to the PhD subject Doctorat-1922-KM-01.
The MEUST (Mediterranean Eurocentre for Underwater Sciences and Technologies) platform offers a unique infrastructure at the bottom of the Mediterranean sea (2500m deep 40km offshore Toulon) to carry scientific research.
Among other projects, a high energy resolution Germanium spectrometer will be installed to monitor the environment radioactivity. The unprecedented gamma measurements, will allow to perform groundbreaking measurements of radioactivity at this depth. The ability to identify, with high precision, the presence natural or man-made radioactive isotopes, offer the possibility to better understand, with a totally novel tool, the dynamics and discharge of submarine groundwater.
Furthermore, comparison of Ge data with classical salinity, current, and other water parameters, offer the possibility to study the correlation of seabed radon emanation and seismic and earthquake activity.
Finally, the existence of a deep Ge spectrometer opens very important opportunities for a new underwater neutron activation technique.
In this context, we offer the chance to a master 2 student to work with us on characterizing the radioactivity detector before it is deployed in the sea most likely during the summer. If successful, the student could then carry on a PhD to exploit the data recorded by the detector.
KM3NeT/ORCA (Oscillation Research with Cosmics in the Abyss) is a deep sea neutrino telescope currently under construction at a depth of 2500m in the Mediterranean Sea off the coast of Toulon. ORCA is optimised for the detection of low energy (3-100 GeV) atmospheric neutrinos and will allow precision studies of neutrino properties. The first ORCA detection strings will be deployed late 2018 and early 2019.
During this intern-ship, at the Centre de Physique des Particules de Marseille, the student will actively participate in the data taking of the ORCA detector and analyse those data. The goal of the intern-ship is to extract a clean signal of upgoing atmospheric neutrinos, based on the data sample of the first few months.
Links: http://antares.in2p3.fr http://www.km3net.org http://www.cppm.in2p3.fr/rubrique.php3?id_rubrique=259
The LHCb experiment at the LHC collider at CERN is designed to study decays of heavy-flavour particles. The goal of LHCb is to perform precision measurements of the parameters of the Standard Model of particle physics and to search for the processes beyond it.
Particle identification, the ability to reliably determine the various species of long-lived charged and neutral particles, is the crucial feature for most of LHCb studies. The student will participate in the development of novel approaches to particle identification and precise measurement of its performance using state-of-the-art machine learning techniques.
The acceleration of the expansion of the Universe was discovered twenty years ago, thanks to the use of type Ia supernovae (SN Ia) as standard candles. The constituent responsible for this acceleration, which accounts for 68 percent of the density of the Universe, has been called dark energy. This phenomenon, which dominates the dynamics of expansion, remains enigmatic.
The future Large Synoptic Survey Telescope (LSST) will revolutionize our knowledge of cosmology. It will observe several tens of thousands of SN Ia under optimal conditions of a precision photometry instrument on the Chile sky. These observations will allow to construct a Hubble diagram with a statistic of SN Ia 20 to 100 times higher than that of the current diagrams which contain 700 of them. To make the most of this statistic, it is necessary to obtain per-mil photometric precision, to limit the bias in determining the luminous distance of SN Ia and of their host galaxy.
Presently, hundreds of millions of stable stars are precisely measured by the GAIA satellite. At CPPM, we develop a method based on a global fit on all these stars in order to correct for instrument and atmosphere variations. It involves manipulating (1G x 100M) size matrices with modern sparse matrix techniques. The CPPM hosts a modern HPC (800 cores, 500 GB to 1500 GB of RAM) that is availlable for the internship. During the internship, we will refine the method, and test performances on simulation. The per-mil precision goal has never been achieved previously. This will allow a characterisation of the dark energy with unprecedented precision. This work is done in collaboration with SLAC/Stanford colleagues.
Following the Master 2 internship, a thesis (2019-2022) is proposed on this topic. It is subject to be funded by the local doctoral school.
Positron emission tomography (PET) is a technique that uses specially designed positron emitting radioactive tracers to image the functions of the body non-invasively. In conventional PET, the basic process employed is the annihilation of an emitted positron and an electron that results in two almost co-linear gamma-photons traveling in opposite directions, each with 511 keV energy. The measure of this gammas by opposite detectors give us line of response (LOR), and images of radioactive tracers are computing by accumulation of this LOR.
From time to times (rate < 5% in water), annihilation results in three coplanars photons. The low rate is compensated by the fact that detection of the three gammas gives directly the position of annihilation (from the measurement of energy and the use of momentum conservation ).
The objective of this internship will be 3-photon imaging by using three Compton cameras. Compton cameras have large field of view with a high sensitivity which are key advantages for this application.
The trainee will simulate with the help of GATE (Monte carlo software, ) the three-photon annihilation and detection with Compton cameras with the GATE Monte Carlo simulation software .
Main tasks will be to:
- Implement three-photon annihilation in GATE
- Simulate the imaging setup comprising three Compton cameras
- Start to establish hardware requirements needed for Compton cameras in order to compete conventional PET
 Abuelhia, E., Kacperski, K. Spyrou, N.M. J Radioanal Nucl Chem (2007) 271: 489. https://doi.org/10.1007/s10967-007-0235-9
 Jan S. et al., GATE a simulation toolkit for PET and SPECT. Phys. Med. Biol., 2004, 49, 4543
L'équipe imXgam du Centre de Physique des Particules de Marseille (CPPM) participe au développement de caméras Compton pour des applications de démantèlement nucléaire (projet TEMPORAL) et pour l'imagerie des gammas prompts lors de séances de traitement en protonthérapie (projet CLaRyS). Un prototype de caméra Compton constitué d'un absorbeur et d'un diffuseur en CeBr3 couplé à une matrice de SiPM a été assemblé . Parallèlement, un modèle Monte Carlo de la caméra a été implémenté sous GATE, qui a permis de développer une méthode de reconstruction d'image événementielle poly-énergétique basée sur l'algorithme MLEM. Cette méthode appelée PE-MLEM  permet de reconstruire la distribution d'activité et d'énergie de sources gamma à partir d'événements Compton dans la gamme d'énergie allant de 200 keV à 2 MeV. L'objectif du stage est de caractériser expérimentalement les performances de la caméra, en particulier sa résolution angulaire, et de valider l'algorithme PE-MLEM sur des données réelles. Des mesures seront effectuées à l'aide de sources radioactives dans le but de cartographier précisément la réponse de la caméra et sa sensibilité. Celles-ci seront comparées aux prédictions Monte Carlo du modèle simulé avec GATE, ce qui nécessitera entre autres de déterminer la résolution spatiale et la résolution en énergie des modules de détection au CeBr3 de la caméra Compton.
 A. Iltis, H.Z. Hmissi, C. Tata, G. Zeufack, L. Rodrigues, B. Mehadji, C. Morel and H. Snoussi (2018) First images from a CeBr3/LYSO:Ce Temporal imaging portable Compton camera at 1.3 MeV, in Conf. Rec. NSS/MIC 2018
 B. Mehadji, M. Dupont, Y. Boursier and C. Morel (2018) Extension of the List-Mode MLEM algorithm for poly-energetic imaging with a Compton camera, in Conf. Rec. NSS/MIC 2018
Cherenkov Telescope Array (CTA) is a worldwide project to construct the next generation ground based very-high-energy gamma-ray instrument. CTA will provide an unprecedented insight into the VHE Universe and in particular will explore the energy region above few tens of TeV for the first time. One of the main goals of CTA is the understanding of the origin of galactic cosmic rays. Astrophysical sources emitting gammas at energies above 50 TeV are very good candidates for cosmic ray accelerators at PeV energies (PeVatrons). The CPPM group has started since few years to work on the potentiality of CTA in detecting PeVatrons and is also working on the energy calibration of the telescopes.
The internship project will focus on the estimation of the effect of systematic uncertainties coming from the calibration accuracy of the instrument on the potentiality of detecting PeVatrons with CTA. The method to identify potential PeVatrons candidates during the the galactic survey relies on the accurate spectral analysis of the source. The effect of the uncertainties on the energy estimation and detection efficiency will be evaluated to improve the robustness of the PeVatrons selection criteria.
The KM3NeT Collaboration will instrument two deep-sea neutrino detectors in the Mediterranean Sea, a low energy site ORCA in France (5 GeV-10 TeV) and a high energy site ARCA in Italy (1 TeV-10 PeV). Both detectors will have a sensitivity largely improved compared to ANTARES at low and high energies. CPPM is the host lab of KM3NeT-ORCA and has therefore a privileged position in the Collaboration. April 2019, 6 ORCA lines should be in operation. Together with the operational ANTARES detector, we can start the first combined KM3NeT/ANTARES analysis.
There is a good science case at medium energies (100 GeV - 10 TeV) where we may expect neutrino signals coming from colliding winds of galactic binary systems, obscured extra-galactic sources (AGN, GRB).
The main goal of this intern-ship is to compute the high-energy performances of the first 6 strings of ORCA (above 100 GeV) using dedicated Monte Carlo simulations and perform analysis of the combined KM3Net-ORCA/ANTARES analysis on transient astrophysical sources such as gamma-ray bursts, flares of AGNs
The analyses will be performed using C++, python and Root on Linux platforms.
The discovery of the acceleration of the expansion of the Universe, rewarded by the Nobel prize 2011, was made thanks to type Ia Supernovae observations. Since that discovery, understanding the origin of the acceleration, from the so-called dark energy, is one of the major quest of cosmology . Today and in the next generation of surveys, supernova observations will be a key point to constraint the dark energy equation of state. The Cosmology group at CPPM is strongly engaged in this quest with his participation in large supernova programs (SNLS and SNFactory), large scale structure analysis (Boss/eBoss) and the preparation of the future surveys Euclid and LSST.
Hubble diagram which is used to constraint the cosmological models needs two ingredients : a precise measurement of the luminosity distance of the supernova and its redshift. In the past, the measurement of the redshift was made by observing the spectral lines of the supernovae and/or its host galaxy. With the next generation of surveys, one major point will be the impossibility to obtain a spectrum for all the astrophysical objects including the supernovae. In particular for the Large Synoptic Survey Telescope (LSST) which will measure the luminosity of around 27 billions of stars and galaxies during 10 years.
The goal of this internship is to develop a machine learning method to estimate photometric redshifts of the supernova host galaxies and to estimate the impact of using his/her results on the cosmological parameter measurements using real data.
The student will develop an automatic tool using the photometric images. For that he will use Machine Learning methods. One of the different methods very promising for few years is Deep Learning since it shows extraordinary performances in several science fields and won several competitions. Deep Learning to estimate photometric redshifts of galaxies or quasars are already showing results better than the state of the art. The student will benefit of the work already done in this field. The student will then use his results to build an Hubble diagram and measure the cosmological parameters. The student will use SDSS and CFHTLS photometric data together with associated spectroscopy data for training and control.
 Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples, Betoule et al, Astronomy Astrophysics, Volume 568, id.A22
 Photometric redshifts from SDSS images using a convolutional neural , network Pasquet et al, Astronomy and Astrophysics, Volume 621, id.A26
In the era of stage IV experiments the sky will be more revealing than ever. The main pillars of modern cosmology is the Cosmological Principle and the theory General of Relativity, our best description of gravity, to date. The best phenomenological model is named ?CDM where ? stands for the unknown Dark Energy component of the Universe responsible for the primordial and late time acceleration of the Universe, while CDM stands for Cold Dark Matter, which is another unknown component that fills, up to 80% of the total matter of the universe to date, 2019. In order to test this theory, we take advantage of the primordial plasma that produced Baryon Acoustic Oscillations in the early universe. These oscillations evolved in time and they are still imprinted on the large scale structures in the late universe.
This projects has two aims. The first aim is to deepen the understanding of the student on cosmological models. The second aim is to give the student the necessary skills in observational cosmology and large scale structure surveys.
References: Cosmological implications of baryon acoustic oscillation (BAO) measurements, E. Aubourg et al 2015, arXiv:1411.1074 SLOAN DIGITAL SKY SURVEY IV: MAPPING THE MILKY WAY, NEARBY GALAXIES, AND THE DISTANT UNIVERSE, Blanton et al 2017, arXiv:1703.00052
CPPM is currently working on the simulation of crystal/SiPM pair in the monte carlo simulation tool GATE . Inside the crystal, simulation is done by Geant4 engine and is essentially optical simulation which can be speed up by using GPU programming.
The goal of the internship is to use OptiX Ray Tracing Engine to simulate optical part of the pair Crystal/SiPM. OptiX library was already used in order to simulate SPECT system .
 Jan S. et al., GATE a simulation toolkit for PET and SPECT. Phys. Med. Biol., 2004, 49, 4543  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6037296/
Les sujets de stages et une description précise sont téléchargeables ici: https://www.cppm.in2p3.fr/~hachon/stages_service_electronique
Ces stages sont encadrés par des ingénieurs experts dans la conception de systèmes d'acquisition à haut débit, la conception FPGA et d'ASIC.
Pour postuler, envoyer votre CV et votre lettre de motivation, en précisant la référence du stage, à Frédéric Hachon (firstname.lastname@example.org) qui centralise les candidatures.
Si votre profil est en adéquation avec le sujet, nous vous contacterons pour vous proposer un entretien au laboratoire.
Le service mécanique du CPPM propose 1 stages de fin d'étude de 6 mois pour des élèves de Master2 ou de dernière année d'école d'ingénieur dans les domaines de la conception mécanique.
We welcome college and high school students for internships for defined periods of time:
for college level: one week in December (before the Christmas holidays)
for high school students: one week in June (during the baccalaureate exam period)
Contact : Jocelyne Munoz
Since 1998, CPPM accomodates pupils of preparatory classes in order to help them carry out their TIPE.
Most of them obtained, at the time of their TIPE test, a higher grade than the national average and succesfully integrated an engineering school.
Contact: Heide Costantini