PHENIICS Fest 2017

30 mai 2017, 08:35 → 31 mai 2017, 23:00 Europe/Paris

Amphithéâtre Pierre Lehman (Laboratoire de l'Accélérateur Linéaire (LAL))

 

Welcome to the PHENIICS Fest 2017 Indico page!

 

The PHENIICS Fest is a two-day event organized by PHENIICS students and for PHENIICS students, to get together, talk a little science, and share good times. It will be held at LAL (building 200, Orsay campus), in the Pierre Lehmann auditorium on Tuesday May 30^th and Wednesday May 31^st.

Registration is now open, and you can already submit the abstract of your contribution - roughly 5 to 15 lines - whether you want to make a talk or a poster. You must create an indico account to do so and please, be sure to use your institute email address. Note that posters and talks must be in English.

Feel free to contact us if you have any questions!

GroupPicture IMG_4961.JPG IMG_4962.JPG

Poster Poster_PF2017.pdf

mardi 30 mai

Registration and coffee

Introduction and welcome

Hadronic physics

Chairperson: Mr. Luca Cadamuro

1 Deeply Virtual Compton Scattering at Jefferson Laboratory

The internal structure of the nucleon - that is, what ordinary matter is made of and what the laws describing it are at their most fundamental level - is still not fully understood by modern nuclear physics. Form factors provide insight about parton positions while parton distribution functions give information about their momentum distribution inside the nucleon, but no correlations can be established between parton positions and momenta at this level. Introduced in the mid 90’s, Generalized Parton Distributions (GPDs) provide a higher level of information since they correlate longitudinal momentum and transverse position of partons inside the nucleon. GPDs give a three-dimensional description of the internal structure of the nucleon, as well as insights on the nucleon spin structure. It has been established that GPDs are experimentally accessible through Deeply Virtual Compton Scattering (DVCS) and its interference with the Bethe-Heitler process. A worldwide experimental program was started in the early 2000’s, and more specifically, a DVCS experiment studying the process ep -> epγ was performed at Jefferson Laboratory, Hall A (Virginia, USA) between 2014 and 2016. The analysis of the data taken during this latest DVCS experiment will allow us to extract the DVCS helicity-dependent cross sections as a function of the momentum transfer: Q². These cross sections will then allow us to access the GPDs of interest and get insights on their dependence in Q², and thus, improve our understanding of the internal structure of the nucleon. This talk is going to focus on the ongoing analysis of these data.

Orateur: M. Frederic Georges (IPN)

Transparents presentation_FredericGeorges.pdf

2 Generalized Parton Distributions and their covariant extension

The internal structure of hadrons (which are bound-states of quarks and gluons, such as the proton or pion) is difficult to map due to the non-perturbative QCD regime in which the constituents interact. Decades of experiments in the field have allowed us to learn a lot about the distribution of momentum (through what is called parton distribution functions, PDFs) or transverse plane position (through Form Factors). We can generalize these two concepts into Generalized Parton Distributions (GPDs), which encode the correlations between longitudinal momentum and transverse position of partons. The goal of this work is to model nucleon GPDs ab initio. We can mention for example the Dyson-Schwinger framework, one of such possibilities for calculations as close as possible to QCD. The path to GPDs can then go through Light-cone wave-functions, which allow to fulfil one important property of GPDs, called positivity. The issue is that the information is often limited in terms of physical region. But, taking advantage of another property of GPDs, called polynomiality, related to Lorentz invariance of the theory, we can extend the GPD to the complete domain. This is done through the inversion of a Radon transform (which is a mathematical tool often used in computerized tomography). This is the first systematic procedure yielding consistent GPD models fulfilling a priori all theoretical constrains.

Orateur: M. Nabil Chouika (Irfu/SPhN - CEA Saclay)

Transparents presentation_Pheniics.pdf

3 Charmonium production in PbPb collisions at 5.02 TeV with CMS

Charmonium states, such as the J/$\psi$ and $\psi$(2S) mesons, are excellent probes of the deconfined state of matter, the Quark-Gluon Plasma (QGP). The understanding of charmonia production in PbPb collisions requires the inclusion of many phenomena, such as dissociation in the QGP and statistical recombination, on top of cold nuclear matter effects. In this talk, final results on the relative J/$\psi$ and $\psi$(2S) modification, based on the pp and PbPb data collected at $\sqrt{s_{\mathrm{NN}}}$ $= 5.02$ TeV by CMS in 2015, will be reported. The results are compared to those obtained at $\sqrt{s_{\mathrm{NN}}}$ $= 2.76$ TeV over a similar kinematic range.

Orateur: M. Andre Govinda Stahl (LLR)

Diapositivas pheniics_talk.pdf

Break and poster session

Nuclear physics - theory

Chairperson: Mr. Florent Scarpa

4 The atomic nucleus : A natural laboratory of complexity

The understanding of the structural properties of nuclei is a long-standing issue. Indeed, the underlying complexity of a many-body fermionic system in strong interaction, led to the arising of wide panel of phenomena and behavior. Thus an universal treatment of such properties is particularly challenging. We'll give a short overview of the usual techniques used to describe nuclear properties, illustrating each method with several example. Moreover we will discuss the impact of state-of-the-arts nuclear models, on observables of use in apparently unrelated fields, in particular Cosmology. To conclude I'll try to emphasize the link between theoretical description and experimental observables.

Orateur: M. Raphaël-David Lasseri (Institut de Physique Nucléaire d'Orsay)

Transparents lasseri.pdf

5 Nuclear structure calculations: mean-field and beyond

Atomic nucleus is a quantum many-body system whose properties are determined by a number of nucleons and the interaction between them. The comprehensive theoretical framework for the description of nuclear systems should therefore be able to account for more than 3000 observed and thousands still unobserved nuclei, including their ground-state, excited-state and reaction properties. It turns out to be as complicated as it sounds. However, not everything is hopeless and significant progress has been made over the last decades. In this talk I will introduce you to basic features of one of the most successful frameworks on the market, the nuclear energy density functional theory. It is essentially a two-step process: starting from the mean-field calculation (step one), we employ the generator coordinate method (step two) in order to calculate collective properties of atomic nuclei that can then be compared to the experiment. The performance of our model will be tested in a study of neon isotopic chain structure, whose clustering properties have recently attracted both experimental and theoretical interest.

Orateur: M. Petar Marevic (IPNO/CEA)

Slides PF_Marevic.pdf

6 Interfacing Many-Body methods and EFT interactions

Through the study of neutron matter, we emphasis the importance of adapting the many-body techniques to the way the nuclear interaction derived from an Effective Field Theory have been renormalized.

Orateur: M. Mehdi DRISSI (CEA/SPhN)

7 Recent developments in Bogoliubov Many-Body Perturbation Theory

In the recent years, so-called *ab initio* methods have know a resurgence of interest among the nuclear theory community. Recent investigations [Tichai et al., 2016] have shown that Many-Body Perturbation Theory (MBPT), when using Hamiltonians evolved through the Similarity Renormalization Group method, could provide results competing with more demanding techniques like Self-Consistent Green's Functions or Coupled-Cluster. Recent efforts have been made to extend this formalism to Bogoliubov reference state that break the symmetry associated with the number of particle [Duguet and Signoracci, 2017]. We will here present extension of the BMBPT formalism to higher orders as well as first numerical results.

Orateur: M. Pierre Arthuis (CEA/DRF/IRFU/SPhN)

Transparents TalkArthuisPHENIICS.pdf

Medical imaging

Chairperson: Ms. Marharyta Alokhina

8 Development of the Fast and Efficient Gamma Detector Using Cherenkov Light for Positron Emission Tomography

Positron emission tomography (PET) is a nuclear imaging technique widely used in oncology. Decay of the tracer emits positrons, which annihilate in the nearby tissue. Two gamma quanta with the energy 511 keV are produced by positron annihilation and allow one to reconstruct the annihilation vertex and distribution of the tracer activity in the body of the patient. I developped an innovative detector using the Cherenkov photons produced by electrons from the photo-ionization conversions of 511 keV gamma, with a high efficiency and time resolution, in parallel with some simulations. I will present in my talk some basics about PET, then the detector which I built and my first results.

Orateur: Mlle Clotilde Canot (CEA IRFU)

Transparents 2017_05_30_vf.pdf

9 MAPSSIC: a novel CMOS intra-cerebral beta+ probe for deep brain imaging in awake and freely moving rat

Preclinical behavior neuroimaging gathers simultaneous assessment of behavior and functional brain imaging. This complementarity is seen as a critical step for comparing animal to human behavior and consequently assess the validity of preclinical studies in drug development. Achieving such a combination is difficult, anaesthesia or restraints inherent to micro-PET imaging precludes its use for behavior studies. In that context, we have presented an original strategy using submillimetric pixelated probes to directly measures positrons inside the rat brain. The small positrons detection volume around the sensor is comparable with rat brain loci sizes ; integrated electronics and wireless communication system allows fully freely-moving rats experiments. Former intracerebral probes have shown promising results but have suffered from various detection limitations. This talk will present MAPSSIC, a novel β$^+$ probe benefiting from innovative CMOS MAPS sensors to overcome these limitations.

Orateur: M. Luis Ammour (Université Paris-Sud - IMNC)

Transparents pheniics_fest_talk.pdf

13:20 LUNCH

Guest speaker: Valérie Masson-Delmotte - Intergovernmental Panel on Climate Change: lastest updates!

slides pheniics-2017-vmd.pptx

Break and poster session

Nuclear physics - experimental

Chairperson: Mr. Loïc Thulliez

10 Gamma-ray cascade study in Kr and Ba fission fragments with the EXILL experiment

The poor accuracy of microscopic models in the prediction of fission observables constrains nuclear industry to rely on semi-empirical models, which in turns need systematic and accurate experimental data on a significant number of observables. In the last decade, large efforts were made in the fission community to improve models of the fission process and of the de-excitation of fission fragments. This is performed through reliable Monte Carlo simulations that take into account prompt neutrons and gamma-ray emission. An ultimate aim of such a simulation is to predict e.g. gamma-heating effect in nuclear reactor. The FIFRELIN code developed by CEA Cadarache is able to estimate the intensities of gamma-ray transitions in all the fission fragments. In the EXILL experiment conducted in 2012 and 2013 at ILL, a target made of 235U (and also 241Pu, which was not investigated in this work) was surrounded by an array of high-resolution, germanium gamma-ray detectors and irradiated by an intense cold neutrons beam. We have extracted the intensities of the main discrete gamma-ray transitions in a set of fission fragments, using the triple gamma-ray coincidence technique, and we have compared our results to FIFRELIN outputs. The result of our study on the gamma-ray cascades in Kr and Ba fragment pairs will be presented.

Orateur: M. Michal Rapala (CEA Saclay/IRFU/DPhN/LERN)

Slides Michal_RAPALA-Pheniics_Fest_2017.pptx

11 Simultaneous measurement of the neutron-induced 233U capture and fission cross sections

233U plays the essential role of the fissile nucleus in the Th-U fuel cycle, which has been proposed as a safer and cleaner alternative to the U-Pu fuel cycle. A particularity of 233U is its small neutron capture cross-section which is about one order of magnitude lower than the fission cross-section on average. Therefore, the accuracy in the measurement of the 233U capture cross-section essentially relies on efficient capture-fission discrimination thus a combined setup of fission and γ-detectors is needed. A new measurement campaign of the 233U capture cross-section and alpha ratio has been proposed at the CERN n_TOF facility using the facility's Total Absorption Calorimeter (TAC) coupled with a compact fission detector. For this measurement, a novel cylindrical multi ionization cell chamber was developed in order to provide a compact solution for 14 active targets. Due to the high specific activity of 233U fast timing properties are required and achieved with the use of customized electronics and the very fast ionizing gas CF4. The measurement was recently successfully performed and is expected to provide the neutron-induced capture and fission cross sections for this important isotope, as well as very valuable information on the distribution of energies and multiplicities of the prompt γ-rays emitted after capture and fission reactions. The experimental setup, the n_TOF facility as well as preliminary results will be presented and discussed.

Orateur: M. Michael Bacak (CEA Saclay, Irfu; CERN)

Slides U233_PHENIICS_3005_Bacak_FIN.pdf U233_PHENIICS_3005_Bacak_FIN.pptx

12 The study of gamma emission in the fission process

Prompt fission gamma spectra (PFGS) have been recently measured for the 238U(n,f) and 239Pu (n,f) reactions using fast neutrons produced by the LICORNE directional neutron source. The setup consisted of ionization chambers containing the actinides samples and LaBr3 scintillators to measure the coincident prompt fission gamma rays. Prompt fission gamma rays were discriminated from prompt fission neutrons using the time-of-flight (TOF) technique. The total energies, multiplicities and average energies of gamma-rays per fission were extracted from the PFGS. In addition, information on the dependence of PFGS characteristics as a function of excitation energy was obtained. These experiments provide important nuclear data for reactor physics, as an input for gamma heating calculations, since the gamma heating effect can be under-estimated by up to ~30% with present nuclear data. Furthermore the new PFGS information will be useful from a fundamental physics point of view, where results can be compared with many competing theoretical predictions to refine models of fission process. Observables like multiplicities, mean energies and total energy can shed light on the energy sharing between fragments and the angular generation mechanism in fission process. It will also lead to a better understanding of the competition between neutron and gamma emission.

Orateur: M. Liqiang QI (IPN NESTER)

Slides LIQIANG.pdf

13 Transfer reactions induced with 56Ni: pairing and N=28 shell closure

The experimental study of the neutron-proton pairing is a challenging task that relies on the strength of the physical observables. Binding energies of N = Z nuclei and rotational properties of finite nuclei are some of the tools used up to now. Despite, their robustness to prove other physical phenomena, they are shown to be insufficient to prove the existence of T =0 pairing collectivity. On the other hand, two-neutron transfer reactions have been a powerful tool to understand neutron pairing correlations in nuclei, because the transfer is proportional to the number of pairs. In addition, since the number of neutron-proton pairs decreases very quickly as the neutron-proton imbalance grows, the transfer of a deuteron-like pair from even-even to odd-odd nuclei stands out the best tool to investigate neutron-proton correlations. During spring 2014 the experiment aiming to this study took place at GANIL-Caen with the beam produced by fragmentation with the LISE spectrometer. We performed systematic measurements in inverse kinematics, with a beam of 56Ni. The experiment included a complicated set-up, by using a variety of detectors in a wide range of angles and for different reaction analysis. Part of our data provides information for the study of neutron-proton pairing as well as the study of the N=28 shell closure. The analysis of the (d,t) implements the differential cross-section for transfer reaction to ground state and first excited state of 55Ni. The transfer reaction (d,4He) is of high interest in this work, being particularly suitable for this study since only the ∆T = 0 transitions (transfer of a deuteron) is allowed and will shed light on neutron-proton pairing.

Orateur: Mlle Anastasia Georgiadou (IPN)

Slides Pheniics_Fest2017_fv.pdf

14 First life time measurements in the $^{78}$Ni region with AGATA and VAMOS at GANIL

Yrast (\textit{i.e.} the state with the lower energy for a given spin-partiy) and near-Yrast states were populated in the $^{78}$Ni region by fusion-fission reaction $^{238}$U($^9$Be,X$\gamma$) at GANIL. The prompt $\gamma$-rays were detected by the AGATA array\footnote{S. Akkoyun \textit{et al.}, \textit{AGATA - Advanced GAmma Tracking Array}, NIM A668 (2012) 26-58} and particle identification was achieved using the VAMOS++ spectrometer\footnote{M. Rejmund \textit{et al.}, \textit{Performance of the improved larger acceptance spectrometer : VAMOS++}, NIM A646 (2011) 184-191}. Life time measurements were performed using the Recoil Distance Doppler Shift technique developed at Cologne\footnote{J. Litzinger \textit{et al.}, \textit{Transition probabilities in neutron-rich $^{84,86}$Se}, Phys. Rev. C 92, 064322 (2015)} with the Orsay plunger device OUPS\footnote{J. Ljungvall \textit{et al.}, \textit{The Orsay Universal Plunger System}, NIM A679 (2012) 61-66}. The goal of the experiment was to populate Yrast states in N=51 neutron-rich odd-isotones from $^{89}$Sr ($Z=38$) down to $^{83}$Ge ($Z=32$) in order to study the high-$\ell$ single-particle states effective energy evolution above the $N=50$ shell gap and complement the scarce direct nucleon exchange data presently available\footnote{J.S. Thomas \textit{et al.}, \textit{Single-neutron excitations in neutron-rich $^{83}$Ge and $^{85}$Se}, Phys. Rev. c 76, 044302 (2007)}. These reactions are indeed difficult to exploit with presently available post-accelerated radioactive ion beams (especially for high-$\ell$ orbitals) in this exotic region. More specifically, we have focused our attention on the $\nu 1g_{7/2}$ monopole drift which is key to understanding the possible evolution of the spin-orbit splitting due to the action of the proton-neutron interaction terms in the $^{78}$Ni region. Our strategy was to measure low lying $7/2^+$ states life times as their relative change along the $N=51$ line towards $Z=28$ should reflect their possible $\nu 1g_{7/2}$ composition. The tensor mechanism\footnote{T. Otsuka \textit{et al.}, \textit{Evolution of nuclear shells due to the tensor force}, Phys. Rev. Lett. 95, 232502 (2005)} indeed predicts increasing low-lying $\nu 1g_{7/2}$ single particle components in the wavefunctions approaching $^{79}$Ni. In this talk, the particle identification and the life time measurement method will be presented with some examples.

Orateur: M. Clément DELAFOSSE (IPNO)

Transparents EDDay2017_DELAFOSSE.pdf

Sciences ACO Museum visit

mercredi 31 mai

Registration and coffee

Particle physics

Chairperson: Mr. Thomas Strebler

15 Searches for dark matter particles produced in VBF processes in pp collisions at sqrt(s)=13 TeV with the ATLAS detector

Dark Matter constitutes 80% of the matter in the universe, as confirmed by astrophysical and cosmological observations, but it has never been detected directly. An important role in the search for the dark matter particles is played by the LHC. In particular, scenarios where the dark matter has a coupling to the Higgs boson can be tested at the LHC by searching for the invisible decay of the 125 GeV Higgs Boson. I will present the ATLAS search for the invisible decay of the Higgs boson produced via the vector boson fusion (VBF) mechanism. I will explain the strategy of the analysis, its main features and challenges. I will show that the same topology of events selected within this analysis can be used to test other dark matter models, such as minimal dark matter models.

Orateur: Marta Maria Perego (CEA Saclay)

Transparents perego_pheniics31may.pdf

16 The High Granularity Timing Detector

In 2026 the high luminosity upgrade of the LHC (HL-LHC) will begin, bringing an improvement of a factor up to five for the luminosity (rate of interaction) in comparison to the original design value. One of the implication of the increase of the luminosity is an increase of the pile-up (number of interactions per collision) from around 25 events during the Run1 up to 200 during the HL-LHC for the ATLAS experiment. To mitigate this effect the different detectors of ATLAS need to be upgraded and new ones need to be installed, one of the new detector is the High Granularity Timing Detector (HGTD) a detector able to mesure the time of passage of particle with a very high precision. This detector would be situated in the end-caps of ATLAS at a distance of 3.5 meters of the interaction point. In this presentation I will present the technology behind the HGTD and explain how timing information can be use to mitigate the effect of the pile up in the condition of the HL-LHC. I will then give you a more concrete exemple of this detector capability with a 5D electron reconstruction tested using a full simulation event with a pile-up of 200 in the ATLAS detector.

Orateur: M. Corentin Allaire (LAL)

17 Development of new n-on-p active edge pixel detectors for ATLAS Inner Detector Upgrade

Silicon detectors are playing a key role in High Energy Physics (HEP) experiments due to their superior tracking capabilities. In view of the upgrade plans of ATLAS experiment toward the high luminosity, the silicon tracking detector (ITK) will be operated in a very intense radiation environment. This work addresses the study of active edge n-in-p planar sensors. Active edge planar pixel sensors are promising candidates to instrument the inner layers of the new ATLAS pixel detector for HL-LHC, thanks to its radiation tolerant properties and the increased fraction of active area due to a distance as low as 50μm between the last pixel implants and the activate edge. This presentation will show the recent results of different and new characterization technique of silicon pixel detectors.

Orateur: Mme Tasneem Rashid (LAL)

Transparents Tasneem-PheniicsFest2017.pdf

Astrophysics and cosmology

Chairperson: Mr. Hélion Du Mas Des Bourboux

18 Allsky search for long duration gravitational waves detection

From September 2015 to January 2016, Advanced LIGO conducted its first observation run (O1) with a sensitivity more than three times better than the initial detectors'. We describe a search for long duration gravitational wave transients in the O1 data. This complements the all-sky un-modelled transient search by looking for gravitational waves of durations of many hundreds of seconds. The search pipeline coherently combines data from all detectors and reconstructs the signal energy using seed based clustering methods without assumption on the signal waveform. We present the status of the search and its performance.

Orateur: M. Valentin FREY (LAL)

Transparents

• EarthEffectExag.mp4
• EarthEffectExag.ogg
• Gravitational_Waves_from_GW150914.mp4
• Gravitational_Waves_from_GW150914.ogv
• LongGWsearch.pdf
• LongGWsearch-v2.odp
• MichelsonInterferometer.mp4
• MichelsonInterferometer.ogg

19 The Cosmic Microwave Background

Physical Cosmology, as it is today understood, began with the development in 1915 of Albert Einstein's general theory of relativity, followed by major observational discoveries in the 1920s. One of the major theories that emerged was that of the Big-Bang. With it follows many predictions of behaviour and properties of our Univers. What is it size? its content? its age? Those are few of the many questions Cosmology tries to answer. Many of them can be solved when observing the so-called Cosmic Microwave Background (CMB), one of the oldest relic of the early univers era. For a few decades now, the Cosmic Microwave Background is one of the most sought probes of the Big-Bang. Since its first evidence in 1964, measurements have drastically being improved. Today, many conclusions were drawn, and many more still need to be.

Orateur: M. Sylvain Vanneste (Laboratoire de l'accélérateur Linéaire, groupe Cosmologie)

Transparents CMB_SylvainVanneste.pdf

20 First measurement of the growth rate of structures with the SDSS-IV eBOSS DR14 quasar sample at z~1.5

One of the biggest questions of contemporary cosmology is the origin of cosmic acceleration : does it arise from a constant vacuum energy as assumed in ΛCDM or from another form of dark energy that varies in time and space, or from a breakdown of general relativy on cosmological scales? To distinguish between these possibilities, one promising technique is to measure the growth rate of structures in data and to compare it with the prediction from general relativity. The eBOSS multi-object spectrograph has undertaken a survey of quasars in the almost unexplored redshift range 0.8 < z < 2.2. In this talk, I will present the first measurement of the growth rate of structures from the 2-point correlation function of the spectroscopically confirmed eBOSS DR14 quasars which correspond to 2 years of data taking. I will present the applicability of the model we are using to fit the correlation function of quasars at this redshift and the systematics tests we performed using simulated populations of quasars as benchmark for the analysis.

Orateur: Mme Pauline Zarrouk (CEA-Saclay)

Transparents pzarrouk-pheniics-May2017.pdf

Break and poster session

Neutrinos

Chairperson: Mr. Steven Calvez

21 Search for heavy neutrinos with the T2K experiment

In the Standard Model of particle physics, neutrinos are massless. But, from neutrino oscillations experiments, we know that they are massive. The question is: how do they acquire these non-zero masses ? One of the possible explanations introduces new heavy neutrinos states, with a mass of few keV to GUT scale, that would mix with light neutrinos. Not only would they explain neutrino masses but they could also give answers to other enigmas, such as the dark matter composition and the matter-antimatter asymmetry in the Universe. Using T2K experiment, a neutrino oscillation experiment located in Japan, it is possible to search for such particles (at 100 MeV-scale) that would be produced along the standard neutrino beam and then decay in the T2K near detector. After introducing the theoretical framework, the presentation will focus on the studies of expected signal and background in the near detector in various decay modes, used to put constraints on heavy neutrinos mixing with standard neutrinos.

Orateur: M. Mathieu Lamoureux (CEA Saclay, IRFU)

Transparents 17-05-30_PHENIICS_heavyNu_T2K.pdf

22 The STEREO experiment, a search for sterile neutrino at ILL

Neutrinos - abundant but elusive particles - appear to be good candidates to look for physics beyond the Standard Model. Although our current understanding succeeds to compile most of the data into a three neutrino mixing framework, there are still experimental anomalies that need to be explained, such as the Reactor Antineutrino Anomaly (2011). The latter can be solved by introducing a light sterile neutrino into which neutrinos would oscillate. The Stereo experiment is designed to test this hypothesis, by placing a neutrino target at a 9 meters distance from the ILL research reactor core, in Grenoble, source of electronic antineutrinos. An oscillation pattern - if any - will be measured both in energy and in distance thanks to a segmented detector. After an introduction to neutrino physics, I will expose the principle of the Stereo experiment, as well as the status of the ongoing analysis of first collected data.

Orateur: Aurélie Bonhomme (CEA)

Transparents ABonhomme_STEREO_PheniicsFest.pdf

23 An innovative Neganov-Luke-assisted light detector for the sensitivity enhancement of CUORE experiment

The neutrinoless double-beta decay ($0\nu$-DBD) is a hypothetical rare nuclear transition producing only two electrons in the final state. Its discovery would have important consequences, demonstrating the Majorana nature of neutrino, allowing the measurement of its absolute mass scale and proving the non-conservation of the lepton number. Nowadays CUORE - with its 988 TeO$_{2}$-based bolometers searching for $0\nu$-DBD of $^{130}$Te at 2527 keV - is one of the most sensitive experiment, but it is not a background free experiment because of $\alpha$ particles with degraded energy emitted by surface contamination. A promising solution to this problem is the detection of the around 100 eV of Cherenkov light produced by the $0\nu$-DBD events. We have recently proved that our Neganov-Luke-assisted light detector can measure this tiny signal thanks to the amplification of thermal signals by a superimposed electric field. We tested the performances of this device coupled to a CUORE bolometer in the Laboratoire Souterrain de Modane (FR): we obtained a signal amplification of 12.7, improving the signal to noise ratio by a factor 7.1 and reducing the baseline noise from 108 eV to 9.9 eV. The events in the $\beta$/$\gamma$ region were identified with a 95% acceptance with a rejection factor of 99.95% for $\alpha$ particles.

Orateur: Mlle Valentina NOVATI (CNRS-CSNSM)

Transparents 20170531_PhDdays.pdf

24 CUPID-Mo: A Double beta decay experiment with Li<SUB>2</SUB><SUP>100</SUP>MoO<SUB>4</SUB> scintillating bolometers

        Neutrinoless double beta decay is a hypothetical rare nuclear transition, whose observation can give us information about the neutrino absolute mass scale and hierarchy. The existence of this process will prove that lepton number conservation can be violated and consequently the Standard Model should be extended.

        The subject of my PhD thesis is focused on the search for this decay in the isotope ¹⁰⁰Mo. My main activity aims at the preparation and operation of an underground bolometric pilot experiment named CUPID-Mo, which adopts the technology developed within the project LUMINEU. This approach foresees the use of cryogenic scintillating bolometers as detectors to search for double beta decay. They are made of scintillating crystals of Li2100MoO4 coupled to NTD Ge thermistors and light detectors, and work in the range 10-20 mK.

        R&D tests of enriched Li₂¹⁰⁰MoO₄ crystals were performed at the Underground Laboratory of Modane (LSM) during several runs, showing excellent results in terms of radiopurity and performance. The outcome of the R&D allowed us to move to the next stage of the experiment, named CUPID-Mo demonstrator. This experiment will be performed in LSM before the end of 2017 with 20 enriched Li₂¹⁰⁰MoO₄ crystals, with the goal to achieve a background of 10^-3 counts/keV/kg/y in the ROI and to prove that this technology meets the CUPID (CUORE Upgrade with Particle Identification) requirements for a ton-scale experiment.

Orateur: Mlle Anastasiia Zolotarova (CEA/IRFU/SPP)

Slides PhDDays_zolotarova.pdf

13:20 LUNCH

PhD associations

25 D2I2

Orateur: Claire Portail (Institut de physique nucléaire)

Transparents d2i2_PheniicsFest.pdf

26 Synapse

Orateur: Mlle Anastasia Georgiadou (IPN)

Slides SYNAPSE_SLIDES_STUDENTS.pdf

27 SFP

Orateur: Antoine Laudrain (LAL-ATLAS)

Transparents PheniicsFest2017_SFP_AntoineLaudrain.pdf

Guest speaker: Georg Schnabel - Watch out! Laplace's demon tries to lure us into the technical singularity

slides pheniics-2017-vmd.pptx

Break and poster session

Accelerators

Chairperson: Mr. Pierre Favier

28 Development of new metrology protocols for chalcogenide materials related to process parameters

Chalcogenide materials are composed of S, Se or Te elements from group VI of the periodic table. For these elements, the sequence of S, Se and Te shows that bonding changes from molecular, covalent, to metallic. They are receiving extensive interest not only for application in advanced memories (Phase Change RAM, Current Bridge RAM) and photovoltaics (i.e. CZTS: Cooper Zinc Tin Sulfide), but also in the development of 2-D materials based in transition metals (e.g. MoS2, WS2) [1]. The properties of the chalcogenides are deeply influenced by the chemical composition, the surface/interface effects and the depth-profile compostion [1]. Hence adequate metrology needs to be developed to probe these materials. The objective of this PhD is to develop advanced metrology protocols required to support the development of the novel chalcogenide materials and their integration in complex technological stacks. The chemical composition is being investigated using Wavelength Dispersive X-Ray Fluorescence (WD-XRF). The composition profiles is under study by combination of X-Ray Reflectometry (XRR) with Grazing Incidence X-Ray Fluorescence (GI-XRF). These in-depth investigations run on state-of-the-art tools and they is being complemented by fluorescence (GiXRF) experiments at the SOLEIL/Metrology synchrotron line. X-Ray Photoemission Spectroscopy (XPS) and Angle-Resolved XPS protocols is under development for surface/interface effects and shallow elementary depth profile. The combination of Lab and synchrotron based metrology will allow detailed understanding of the chemistry of chalcogenide thin films. The metrology protocols will be applied to the characterization of innovative films elaborated by PVD and CVD (ternay alloys, 2D transition metal dichalcogenides, etc). Key-words: Chalcogenides; Thin-films; Chemical composition; X-Ray Metrology; XRF; XPS; GIXRF-XRR [1] Tanaka, Keiji, and Koichi Shimakawa. Amorphous chalcogenide semiconductors and related materials. Springer Science & Business Media, 2011.

Orateur: M. Walter BATISTA PESSOA (LETI CEA-GRENOBLE)

29 Residual Ion Dynamics in Electron Storage Rings

Ions produced by ionization of the residual gas in electron storage rings can significantly degrade the performance of a machine and produce various beam instabilities. To cure more effectively these problems it is important to understand the ion dynamics in the accelerator. The ions undergo the effect of the electron beam crossing and go through strong transverse oscillations and a longitudinal drift. In this talk a model of the ion motion will be presented, simulation results including the beam ion interaction and ion clearing means will be explained in ThomX case.

Orateur: M. Alexis Gamelin (Laboratoire de l’Accélérateur Linéaire)

Transparents Pheniics2017_Gamelin.pptx

30 Study of the electron transport for the FEL beam line COXINEL experiment using a beam produced by plasma laser acceleration.

The COXINEL experiment aims to demonstrate the free electron laser amplification with an electron beam produced by laser plasma acceleration. For this, a transport line was designed and prepared at the Synchrotron SOLEIL. It consists of three permanent magnet quadrupoles with variable gradient (QUAPEVAs), a demixing chicane, a second set of electromagnetic quadrupoles and a 2 m undulator. This line was installed at the LOA. The laser plasma acceleration regime, carried out in an injection by ionization in a gas jet, was initially chosen to commission the transport line. The electron beams produced in this regime are stable, have a wide energy spectrum (50-250 MeV) and a wide divergence (several mrad depending on their energy), the properties of the beam have been controlled and manipulated using different optics along the transport line. The beam was characterized every 1-2 m. We present here the measurements carried out on the COXINEL line with the first observation of the radiation of the undulator at 200 nm. These results are compared with numerical simulations, using a homemade tracking code.

Orateur: M. Thomas ANDRE (Synchrotron SOLEIL)

Nuclear energy

Chairperson: Ms. Alice Somaini

31 Study on X-ray diagnosis for phase distribution during corium-sodium interaction

In case of a severe accident scenario in sodium-cooled fast reactors, the fuel in the core would melt, generating a hot mixture termed as corium. This corium will then be discharged into the sodium pool through the guide tubes. When the hot molten corium comes in contact with sodium, called Molten Fuel-Coolant Interaction (MFCI), it might generate a violent explosion. Such an explosion can be visualized using an X-ray radioscopic device. The PhD thesis aims to study the X-ray diagnosis and develop an X-ray imaging algorithm in order to better realize the interaction mechanism. This study will help us to analyze the three phase repartition (i.e. corium, liquid sodium and its vapors) during such an interaction being carried out in the upcoming experimental facility PLINIUS 2 at CEA, Cadarache. A major difficulty is to detect the extreme fine fragments of corium (~100 microns) in sodium which is beyond the detection limit of existing tools. This talk will focus on the development of initial models of the representative corium fragments and the associated image processing and analysis techniques, to better realize the interaction mechanism.

Orateur: Mlle Shifali SINGH (CEA, Cadarache)

Transparents PHENIICS_Fest_SS.pdf

32 Quench Tests Analyses of the First JT-60SA Toroidal Field Coils

**JT-60SA** is a fusion experiment which is jointly constructed by Japan and Europe, and which shall contribute to the early realization of fusion energy by providing support to the operation of ITER and by addressing key physics issues for ITER and DEMO. The JT-60SA is based on the existing infrastructure of JT-60U experiment and is upgraded by using **superconducting coils**. JT-60SA tokamak consists of 18 **Toroidal Field (TF)** superconducting coils which will be provided by European industry and tested in a **Cold Test Facility (CTF)** at CEA Saclay. In order to check the performance of the JT-60SA TF coils and hence mitigate their possible fabrication risks, the coils have been cooled in the CTF with supercritical helium at **5 K** and have been supplied at the nominal current of **25.7 kA**. One major test performed is the so-called “**quench test**”, or “**temperature margin test**”, during which the inlet helium temperature of the **Winding Pack (WP)** is controlled to increase progressively up to quench followed by a fast discharge of current during about **60 s**. The measurements of voltage, pressure and temperature allow me to study the **quench propagation** in the coil and the corresponding physical phenomena. **Four quench dynamic phases** will be identified during the analyses of the coils behavior.

Orateur: M. Yawei HUANG (CEA Saclay)

Transparents PHENIICS_Fest_2017_-_YH_v3.pdf

33 Polynomial Axial Expansion for 3D method of characteristics applied to neutron transport

In the recent years a solver based on the Method of Characteristics (MOC) allowing the treatment of 3D extruded geometries has been developed inside the TDT module of APOLLO3®. The standard Step Characteristics (SC) approximation is used and results show an excellent agreement with Monte-Carlo simulations. However a fine mesh refinement is needed to converge the strong flux gradients customarily appearing in 3D reactor physics applications. An improvement of this method is proposed: the results of the previous work show that much of the flux variations are likely to be represented by a polynomial basis along the vertical direction. Since most of the geometrical and physical heterogeneities are radially located, the SC approach is preserved to represent the solution over the radial plane. As a matter of fact the strong irregularities in the geometrical meshes prevent from an efficient use of a polynomial expansion. On the contrary along the axial direction the computational meshes assume a Cartesian shape, well suited for a polynomial representation of sources and fluxes. A convenient polynomial development in this direction allows us to approximate the strong flux slopes without the help of a large number of axial meshes.

Orateur: M. Laurent Graziano (CEA)

34 Learning of the importance map in a direct Monte Carlo shielding calculation with the particle transport code TRIPOLI-4(R)

TRIPOLI-4® is a Monte Carlo code that simulates the transport of particles (Neutrons, Photons, Electrons) and provides reference solutions that are used to validate faster deterministic codes. In radiation shielding studies, engineers use Monte-Carlo codes to estimate radiation doses rate due to radioactive sources, given a description of the problem geometry. However, Monte Carlo methods may converge very slowly if the score of interest (i.e. the dose rate) is dominated by rare events. Therefore, it is necessary to use variance reduction techniques to reduce the statistical uncertainty on the expected result. Most of these techniques require a prior knowledge of the problem in the form of a so-called importance map, which represents an estimate of the likelihood that a particle will contribute to the score as a function of its phase space coordinates. The map helps the code to choose which particles are likely to contribute to the score and therefore worth simulating. The aim of this work is to improve the figure of merit of a Monte Carlo run by learning from histories of events with Machine Learning algorithms.

Orateur: Michel Nowak (CEA)

Transparents pheniics_MichelNowak.pdf

Awards ceremony and closure

19:30 Social dinner