4 sujets /DPhN/LEARN

Dernière mise à jour : 08-08-2020


 

Antimatter, hypernuclei: need to know the antiproton-nucleus interaction

SL-DRF-20-0229

Research field : Nuclear physics
Location :

Service de Physique Nucléaire (DPhN)

Laboratoire etudes et applications des reactions nucleaires (LEARN) (LEARN)

Saclay

Contact :

Jean-Christophe DAVID

Starting date : 01-10-2020

Contact :

Jean-Christophe DAVID
CEA - DRF/IRFU/DPhN/LEARN

0169087277

Thesis supervisor :

Jean-Christophe DAVID
CEA - DRF/IRFU/DPhN/LEARN

0169087277

Laboratory link : http://irfu.cea.fr/dphn/Phocea/Vie_des_labos/Ast/ast_visu.php?id_ast=2105

Antiproton-nucleus reactions can occur at rest or in flight. The reactions at rest, or almost (~100 eV - 1 keV), are notably used at the Antiproton Decelerator (AD) at Cern by different experiments (GBAR, ASACUSA, AEgIS, ALPHA, ATRAP,). At FAIR, the PANDA project (antiProton ANnihilation at DArmstadt) aims to study hypernuclei with in-flight reactions (~GeV). In both cases, reliable simulations are necessary for a good analysis of the results. This is where we propose to make our contribution.



The INCL calculation code (IntraNuclear Cascade Liège) developed at the CEA (Irfu/DPhN) processes hadron-nucleus reactions for energies up to 20 GeV. Recognized for its reliability, it has recently been extended to the production of strange particles and hypernuclei (with the help of the ABLA de-excitation code), and can also be used within the Geant4 transport code. The extension to antiproton-nucleus reactions will therefore make it possible to participate in PANDA’s studies on hypernuclei, with a first step of tests on data already available (obtained at LEAR), as well as in the experiments of the Antiproton Decelerator where the behaviour of anti-hydrogen atoms is studied.



In addition, INCL is able to treat nucleus-nucleus reactions when one of the nuclei is light (A <= 18). This could also be used to treat by extension reactions with anti-deuteron and anti-helium. The GAPS experiment (General Anti-Particle Spectrometer) aims precisely to measure the fluxes of these particles in cosmic radiation. Simulations are obviously necessary in this case and INCL could thus contribute to this.

The nuclear fission process in the light of prompt gamma-rays

SL-DRF-20-0339

Research field : Nuclear physics
Location :

Service de Physique Nucléaire (DPhN)

Laboratoire etudes et applications des reactions nucleaires (LEARN) (LEARN)

Saclay

Contact :

Thomas MATERNA

Starting date : 01-10-2020

Contact :

Thomas MATERNA
CEA - DRF/IRFU/DPhN/LEARN

0169084091

Thesis supervisor :

Thomas MATERNA
CEA - DRF/IRFU/DPhN/LEARN

0169084091

Personal web page : https://www.researchgate.net/profile/Thomas_Materna

Laboratory link : http://irfu.cea.fr/dphn/Phocea/Vie_des_labos/Ast/ast_groupe.php?id_groupe=498

Although known and studied for more than 80 years, nuclear fission remains a very active research topic both for its fundamental aspect of the study of nuclear matter and for its applications, including nuclear energy.

Prompt gamma rays allow probing the structure and properties of fragments emitted during the fission process. Their use therefore offers a new perspective for its study. In particular, it makes it possible to explore effects that have not yet been studied experimentally, such as the influence of the shape of the fragments on the fission process or the sharing of excitation energy between the fragments. On the other hand, the measurement of fission-prompt gamma rays also provides valuable data for the simulation of gamma heating in nuclear reactors.

The thesis work will consist in the analysis of the data from the new gamma spectrometer, FIPPS, installed at the Grenoble research reactor. This spectrometer is composed of an array of Germanium detectors arranged around a fissile target placed in an intense flux of thermal neutrons. Experimental results will allow the student to test recent models on the fission and fragment de-excitation processes.

Development of a Micromegas TPC detector for neutron-induced reactions

SL-DRF-20-1118

Research field : Nuclear physics
Location :

Service de Physique Nucléaire (DPhN)

Laboratoire etudes et applications des reactions nucleaires (LEARN) (LEARN)

Saclay

Contact :

Eric BERTHOUMIEUX

Frank GUNSING

Starting date : 01-10-2020

Contact :

Eric BERTHOUMIEUX
CEA - DRF/IRFU/DPhN

01 69 08 75 84

Thesis supervisor :

Frank GUNSING
CEA - DRF/IRFU/DPhN

01 69 08 75 23

Micromegas-based gas detectors are used in several nuclear physics projects. One of these applications is in connection with pulsed neutron beams, making it possible to use the time-of-flight technique to determine the energy of the neutron. Using an electrode with a thin layer containing an isotope to be studied, charged particles from a neutron-induced reaction are detected. In this way it is possible to measure probabilities of reaction. The low probability of interaction of the beam with the deposits can make it possible to put several detectors in series to make relative measurements. By using orthogonal tracks for the Micromegas detector, it is possible to extract the coincidences and thus reconstruct the image of the incident beam, which is also done as a function of the energy of the neutrons. A more in-depth analysis will make it possible to reconstruct the tracks from the point of impact of the neutron and to determine in this way the angular distribution of the reaction studied. The thesis project will be to develop a Micromegas time projection chamber (TPC) for measurements in combination with time-of-flight of neutrons, having excellent resolution in position and in time, and by integrating the associated electronics.



Toward high-precision measurements of neutrino oscillations in the futur long baseline experiments

SL-DRF-20-0424

Research field : Particle physics
Location :

Service de Physique Nucléaire (DPhN)

Laboratoire etudes et applications des reactions nucleaires (LEARN) (LEARN)

Saclay

Contact :

Alain LETOURNEAU

Starting date : 01-10-2020

Contact :

Alain LETOURNEAU
CEA - DRF/IRFU/DPhN/LEARN

33 (0)1 69 08 76 01

Thesis supervisor :

Alain LETOURNEAU
CEA - DRF/IRFU/DPhN/LEARN

33 (0)1 69 08 76 01

The neutrino is currently the only particle in the standard model whose description is not entirely contained in it. His study therefore opens the way to the exploration of a new physics and to addressing very fundamental questions such as the preponderance of matter over antimatter in the universe. Future experiments with accelerator neutrinos (DUNE and T2HK) will measure its oscillation properties with unprecedented accuracy, which will require a high degree of control of uncertainties at the percent level.

One of the dominant uncertainties today is the one associated with the modelling of the neutrino interaction inside the detector. A decrease of this uncertainty would immediately imply an increase in the sensitivity of those experiments.

In this thesis work, we propose to improve the description of the neutrino-nuclei interaction, mainly the modelling of the final state of the interaction, and to evaluate its impact on the sensitivity of current and future experiments. The work will be based on the use and development of a nuclear cascade code coupled with measurement results. The results, coupled with an improvement of the near detector, would be used in the ongoing T2K experiment to improve the measurement of neutrino oscillations.

This work will also benefit to define the characteristics of the near detector in the DUNE experiment, whose components will be tested and validated at IRFU.

• Nuclear physics

• Particle physics

 

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