List of PhD offers of laboratory.

Atlas
IC Design for High Energy Physics experiments
PhD supervisor:
Marlon Barbero - barbero@cppm.in2p3.fr
Description:

The Aix-Marseille University and the ATLAS CPPM group in Marseille have an opening for a PhD (already funded) in the domain of IC design and characterization of depleted CMOS sensors and hybrid pixel electronics for future applications at particle colliders.

The Centre de Physique des Particules de Marseille (CPPM) is a joint research unit of the Centre National de la Recherche Scientifique (CNRS) and the Aix-Marseille University. The CPPM is a leading player in research in Particle Physics, Astroparticle Physics and Observational Cosmology. It is present in the largest physics experiments currently underway or being developed throughout the world.

The CPPM ATLAS group has a long-standing experience on hybrid pixel technologies. It is currently involved in the ATLAS Inner Tracker (ITk) upgrade project, targeting the High Luminosity phase of the Large Hadron Collider (HL-LHC project), and also in developments of technologies for future applications at collider experiments.

We are seeking candidates to join the group and develop CMOS sensors and hybrid pixel electronics in small feature size for particle physics pixel detectors at high intensity and high radiation dose, in the context of several international collaborations and projects.

We are seeking motived candidates that should have skills or strong will to acquire experience in:

- Microelectronics and circuit design.

- Silicon semiconductor process technologies.

- Deep submicron CMOS technologies.

- Design tools, simulation, design and verification.

- Experimental verification, designing test systems, acquisition software.

- Testing complex devices, data processing and data analysis.

Further inquiries can be addressed to: barbero@cppm.in2p3.fr

https://emploi.cnrs.fr/Offres/Doctorant/UMR7346-ANNPOR-077/Default.aspx

Keywords:
Physique des particules
Code:
Doctorat-2225-AT-01
Belle II
Search for lepton flavour violaitng decays $B \to \tau\ell X$
PhD supervisor:
Justine Serrano - 0491827280 - serrano@cppm.in2p3.fr
Description:

Being forbidden in the Standard Model (SM) of particle physics, lepton flavor violating decays are among the most powerful probes to search for physics beyond the SM. In view of the recent anomalies seen by LHCb on tests of lepton flavor universality in $$b\to s \ell \ell$$ and $$b \to c \ell \nu$$ processes, the interest of lepton flavor violating decays involving tau leptons in the initial or final state has been greatly reinforced. In particular, several new physics models predict branching fractions of $$\tau \to \phi\mu$$ and $$B \to K\tau\mu$$ decays just below the current experimental limits.

The Belle II experiment located at KEK, Japan, started to take data in 2019, aiming at collecting 50 times more data than its predecessor, Belle, by 2031. Thanks to its clean environment and high ?+?- cross section, it provides an ideal environment to study decays with tau leptons. The goal of this phD is to exploit the Belle II data in order to obtain the best experimental limits on lepton flavor violating decays such as $$B \to \tau\ell X$$, where X is a hadronic system and $$\ell$$ an electron or a muon.

Activities:

Data analysis, participation to data taking, participation to Belle II service tasks, activities of outreach and dissemination.

Work context:

This phD will take place at CPPM, Marseille (https://www.cppm.in2p3.fr/web/en/index.html). Travels to KEK for collaboration meetings, and longer stay for participation to the data taking, are foreseen.

The funding of this phD is provided by an ERC grant obtained by Justine serrano.

Applicants must hold a Master degree (or equivalent) in Physics, or expect to hold such a degree by the start of employment.

Application must include a CV, grade records, a motivation statement and contacts of three possible persons to supply letter of recommendation.

References:

https://arxiv.org/pdf/1806.05689.pdf

Keywords:
Physique des particules
Code:
Doctorat-2225-BE-01
HESS-CTA
Observation of the PeVatron candidate SNR G106.3-2 with the LST1+MAGIC Cherenkov telescopes
PhD supervisor:
Franca Cassol & Heide Costantini - 0491827248 & 0491827257 - cassol@cppm.in2p3.fr & costant@cppm.in2p3.fr
Description:

The CTA (Cherenkov Telescope Array) is a worldwide project to construct the next generation ground based very high energy gamma ray instrument [1]-[2]. CTA will use tens of Imaging Air Cherenkov Telescopes (IACT) of three different sizes (mirror diameter of 4 m, 12 m and 23 m) deployed on two sites, one on each hemisphere (La Palma on the Canary Islands and Paranal in Chile). The observatory will detect gamma-rays with energy ranging from 20 GeV up to 300 TeV by imaging the Cherenkov light emitted from the charged particle shower produced by the interaction of the primary gamma ray in the upper atmosphere.

The unconventional capabilities of CTA will address, among others, the intriguing question of the origin of the very high energy galactic cosmic rays by the search for galactic sources capable of accelerating cosmic rays up to the PeV energies, called PeVatrons. Recently, the Supernova Remnant (SNR) G106.3-2.7 has been indicated as a highly promising PeVatron candidate [4]. In fact, G106.3-2.7 emits gamma-rays up to 500 TeV from an extended region (~0.2o) well separated from the SNR pulsar (J2229+6114) and in spatial correlation with a local molecular cloud.

The CTA observatory completion is foreseen in 2025 but the first Large-Sized Telescope (LST1) is already installed and taking data in La Palma. LST1 is placed very close to the two MAGIC telescopes [3], which are one of the presently active IACT experiments. This configuration permits to perform joint observations of the same source with the three telescopes LST1+MAGIC increasing the effective detection area and improving the energy and angular resolution, thanks to the enhanced quality reconstruction of stereoscopic data. While the LST1+MAGIC telescopes cannot reach enough sensitivity to access energies above 100 TeV, they can provide exclusive and unprecedented data for establishing the spectral morphology of this exciting PeVatron candidate in the 100 GeV-100 TeV energy region. A campaign of joint observations of G106.3-2.7 will start in 2022 and will continue in the following years.

The PhD project will be on the analysis of the data of the coming campaign, its ambitious target will be to contribute in disclosing the hadronic or leptonic nature of this promising PeVatron. In order to maximize the effective area at very high energy, G106.3-2.7 will be observed at large zenith angle (LZA), 62o-70o, which represents a challenging detection condition. The project will start with the development and verification of the joint LST1+MAGIC stereo reconstruction chain [5] at LZA, using Monte Carlo (MC) data. This MC study will aim to optimize the data reconstruction and selection in order to reach a high quality Instrument Response Function and sensitivity for this specific source. Real data will be then reconstructed so as to achieve both a morphological and a spectral reconstruction of the source in the 100 GeV-100 TeV energy range. Finally, the high-quality LST1-MAGIC data will be used for a multiwavelength analysis that will compare different emission models and try to disentangle the nature of the source.

The project will include the participation to the LST1+MAGIC observation campaign with stays of four weeks in the Roque de los Muchachos Observatory in La Palma.

The CPPM CTA group works since several years in the building and commissioning of the LST1 telescope and on the preparatory studies for the research of galactic PeVatrons with CTA [6][7].

Candidates should send their CV and motivation letter as well as grades (Licence, M1, M2) to cassol@cppm.in2p3.fr and costant@cppm.in2p3.fr before 10/4/2022. Applications will be selected on the base of qualifications and an oral interview.

References:

[1] Science with the Cherenkov Telescope Array: https://arxiv.org/abs/1709.07997

[3] MAGIC Collaboration, Aleksi?, J. et al. Astropart. Phys. 72 (2016) 7694.

[4] Z. Cao et al. Nature, 594, 3336 (2021); M. Amenomori et al. Nature Astronomy, 5, 460464 (2021)

[6] O. Angüner et al. Cherenkov Telescope Array potential in the search for Galactic PeVatrons, ICRC 2019

[7] G. Verna et al. HAWC J2227+610: a potential PeVatron candidate for the CTA in the northern hemisphere, ICRC 2021

Keywords:
Astroparticules
Code:
Doctorat-2225-CT-01
KM3NeT
Study of Neutrino Oscillations with KM3NeT/ORCA
PhD supervisor:
Description:

The Neutrino Team at CPPM is strongly involved in the KM3NeT/ORCA neutrino telescope, under construction in the abyss (-2500m) of the Mediterranean sea, 40km offshore Toulon. The first detection units that have been deployed are successfully collecting data. The detector is now large enough to access yet unexplored physics territories.

The student will contribute to the analysis of the data for the measurement of the atmospheric parameters and attempt the first determination of the neutrino mass ordering.

Activities: Data analysis, development of machine learning techniques, data taking, detector construction, outreach.

Keywords:
Astroparticules
Code:
Doctorat-2225-KM-01
Renoir
Modeling of the NISP instrument response
PhD supervisor:
William Gillard & Escoffier Stephanie - gillard@cppm.in2p3.fr
Description:

Euclid is a class M space mission of the ESA cosmic vision program that have been selected in 2011 by the ESA and to be launch in 2022. The Euclid mission is designed to map the geometry of the Universe in order to understand the origins and nature of the acceleration of the expansion of the Universe that have been discovered in 1998. To do so, the Euclid mission is optimised to investigate the nature of dark energy, dark matter and gravity from the measurement of two independent probes: cosmic shear through the weak gravitational lensing and the matter power spectrum through galaxy clustering. Those measurements are carried by two independent instruments on-board the Euclid spacecraft: a visible imager (VIS) that is optimised for the measurements of the weak gravitational lensing and a near-infrared slit-less spectro-photometer (NISP) dedicated to the redshift measurements needed for the galaxy clustering. One advantage of the NISP slit-less spectroscopy is that the NISP will permits to measure redshift of hundreds of galaxy on a single fields of an angular size comparable to the apparent angular size of the moon. The drawback of the slit-less spectroscopy is that it induces spectra contamination (contamination between neighbourhood sources as well self contamination of extended source) and a high knowledge of the instrument is required to achieve optimal extraction of the observed spectra.

To attain this optimal extraction and reach scientific goal, the NISP slit-less spectroscopic calibration is an important step of the NISP data reduction pipeline as it permits to derive the instrument response used to convert collected data to physical quantity needed for the science. Also, one should not neglect that the accuracy of instrument response knowledge strongly affect accuracy and precision of the scientific outcome. NISP spectroscopic calibration could be achieved through a set of purely parametric functions, as polynomial function, that are disconnected off physical properties of the instrument. One main consequence of using parametric function, is that their parameters are often strongly correlated between each other and, in most of the case, they show degeneracies between several instrumental properties. Additionally any variation of instrument physical properties (as for exemple mechanical stress induced by thermal variation) require to fully re-calibrate the parametric function. This cant not be so easily done with the NISP because the NISP instrument does not carry a calibration source on its board.

In our team, composed of the NISP instrument scientist, former responsible for the NISP spectroscopic calibration, we aims at modelling the instrument response of the NISP based on the physical parameters of the instrument itself, having for objectives to provide a more accurate calibration tool. Additionally, the development of instrument model opens room for predicting instrument behaviour and for deeper study of the instrument systematic, allowing to respond to one of the Euclid/NISP key project that aims at predicting and monitoring scientific performance of the instrument along its lifetime. It also opens the possibility to use the instrument model itself in data processing by mean of forward modelling approach. The objectives of this thesis will be to participate to the development of the instrument model, focusing on the optical properties of the NISP instrument to construct a physical model for the NISP slit-less spectral dispersion based on optical and mechanical properties of the NISP. At this point we stress that our objectives isnt to build a complex raytracing model of the NISP instrument which is CPU and time consuming. Rather, we aim at an analytical approach, relying on physical behaviour of the instrument, to produce fast computing instrument response.

The thesis work will therefore consist analysing the set of data collected by the NISP instrument during the various ground testing campaign to identify NISP physical properties important for the spectroscopy and to model the spectral instrument response. Once model will be achieved and validated with ground measurement and simulation, it will be used by the candidates to infer NISP spectral calibration for the flight data. All along the PhD, the candidate will explore the possibility to used the instrument model response he developed to perform optimal spectral extraction by mean of forward modelling approach and in view of increasing redshift precision measurements.

This thesis obtained a CNES's financial support under reference 2022-106. Hence, any application should pass by CNES's recruitment procedure which will start from 10th of January en which will last until the 31 of marsh 2022 (https://recrutement.cnes.fr/fr/annonces). However, it is highly recommended for the candidats to contact your future PhD supervisor by sending your CV with a cover letter as well as your last transcript (from the previous year and the transcript of the current semester if available).

Keywords:
Instrumentation
Code:
Doctorat-2225-RE-02
Testing general relativity by measuring the growth rate of structure with the Rubin/LSST supernova dataset
PhD supervisor:
Dominique Fouchez - 0491827649 - fouchez@cppm.in2p3.fr
Description:

Twenty years after the discovery of the current acceleration of the expansion of the universe by supernova measurements, the supernova probe remains the most accurate way to measure the parameters of this recent period in the history of our universe dominated by the so-called dark energy.

The precision measurements that can be performed by the supernova probe will be a crucial element that, in combination with other probes (LSS, weak lenses, CMB, etc.), will put strong constraints on the nature of dark energy and explore possible deviations to general relativity. This will be made possible by the exceptional Supernova data set to be provided by LSST, with a combination of huge statistics and extreme calibration accuracy.

The Vera Rubin Observatory is finishing it's construction in 2022 and will be commissioned in 2023. The Large survey of space and time (LSST) will start at full speed at the beginning of 2024, thanks to it's 8.4-metre telescope with a 3.2 billion pixel camera, the most powerful ever built.

This telescope will take a picture of half the sky every three nights for ten years. This survey will make it possible to measure billions of galaxies with great accuracy and to track the variation over time of all transient objects. With many other astrophysical studies, it will be a very powerful machine for determining cosmological parameters using many different probes and, in particular, it will impose strong constraints on the nature of dark energy. The LSST project aims to discover up to half a million supernovae, from which many can be used to probe cosmology. with two orders of magnitude improvement in statistics over the current data set, this will allow accurate testing of dark energy parameters, new tests of general relativity and will also impose new constraints on the universe's isotropy.

In this PhD, we propose to prepare and participate in the first analysis of the data of the LSST supernova with emphasis on measuring the growth rate of structures. The preparation will be carried out by working on the precise photometric measurement and photometric selection of the type Ia supernova together will their link with their host galaxy properties. These two points and selection effects are among the most important sources of systematic errors and all work to reduce and mitigate these sources of error will have a significant impact on the final measurement.

The CPPM LSST group is already engaged in precision photometry work for LSST with direct involvement in algorithm validation within DESC/LSST [1][2][3] and has proposed a new deep learning method to improve the photometric identification of supernovae [4] and photometric redshifts [5]. The doctoral student will work within this framework by applying a complete analysis pipeline built with these tools, which he/she will contribute to improving, to the precursor data currently available like HSC to validate his/her work, and will then have access to the first LSST images and supernova detections to participate in the first analysis of the LSST supernova data set.

The CPPM cosmology group is also involved in the ZTF, DESI and Euclid surveys and collaborates with theorists to study alternative cosmological models, so that extensions of doctoral candidates' work can be found by combining the data with these other suveys and/or by testing a new cosmology through these new supernova data measurements.

Keywords:
Cosmologie observationnelle
Code:
Doctorat-2225-RE-03
Testing dark energy with the ISW effect in the Euclid mission
PhD supervisor:
Stéphanie Escoffier - 04 91 82 76 64 - escoffier@cppm.in2p3.fr
Description:

The various observations of the Universe have been indicating for twenty years now that the expansion of the Universe is accelerating. The standard model of cosmology, known as the LCDM model, describes the Universe as composed of 27% dark matter and 68% dark energy. Understanding the nature of these two energy components remains one of the greatest challenges in contemporary physics. Next-generation galaxy surveys, such as Euclid or DESI, will make it possible to measure several tens of millions of galaxy spectra in the coming decade and tighten constraints on the cosmological model, or probe its alternatives like modified gravity models.

The most promising tools to constrain dark energy and gravity properties are based on the observation of large structures in the Universe. The structure of the Universe also reveals the presence of large under-dense regions, enclosed by filaments of matter. These cosmic voids, which occupy nearly 80% of the volume of the Universe, contain very few matter, and are therefore an ideal laboratory for testing dark energy scenarios.

The subject of the thesis is to extract the integrated Sachs-Wolfe (ISW) signal by cross-correlating cosmic voids with Cosmic Microwave Background (CMB). Indeed the time evolution of gravitational potentials imprints secondary anisotropies in the CMB, in addition to the primordial CMB anisotropies generated near the last scattering surface. These additional anisotropies are caused by gravitational interactions of CMB photons with the growing cosmic large-scale structure. The ISW signal is challenging to measure since it is very weak compared to primordial CMB photons. However the signature of the ISW

effect can be observed as a non-zero signal in the cross-correlation between the distribution of foreground tracers of dark matter (such as galaxies) and the temperature of CMB, providing a direct probe of the late-time expansion of the Universe. Recent work (Kovacs 2021) has shown that the ISW signal amplitude exhibits an excess over the expectations of the standard LCDM model, at the 3 sigma level, especially when the study is applied to superstructures such as supervoids.

The thesis project focuses on the ISW effect and the cross-correlation between the CMB and cosmic voids. The work of the student will consist in building the void catalogs from galaxy catalogs, developing estimators and likelihoods associated with the ISW effect and quantifying how the ISW effect impacts onto dark energy and modified gravity parameters.

The CPPM is involved in the two projects DESI and Euclid, both dedicated to the measurement of cosmological parameters to constrain dark energy and test modified gravity models.

DESI is a galaxy survey that started in 2021 for 6 years and will observe nearly 40 million spectra of galaxies up to a redshift of 3.5. Euclid was selected by the European Space Agency (ESA) in 2011 and will be launched in 2023 to probe the Universe over a 6 year-period. These data will revolutionize our ability to map the Universe and better understand the nature of dark energy or put Einstein's General Relativity (GR) in default.

Application should be done via the CNES website:

https://recrutement.cnes.fr/fr/annonce/1498789-175-testing-dark-energy-with-the-isw-effect-in-the-euclid-mission-13009-marseille

A CNES/CNRS funding can be obtained for this thesis.

Keywords:
Cosmologie observationnelle
Code:
Doctorat-2225-RE-01