Science

INTERNSHIP Ref. : LSS_01

Neutron imaging provides unique opportunity for studying technologically and biologically relevant materials as a complementary modality to other techniques. The increased interest in neutron imaging relies on their strong penetration into metallic materials, their sensitivity to light elements, and the possibility of manipulating contrast via isotope substitution. Among the imaging approaches, propagation-based phase-contrast imaging recently showed a promising extension to conventional absorption-transmission imaging. This method, well established with synchrotron X-ray radiation, relies on a (partially) coherent beam and carefully controlled experimental conditions to convert phase variations of the incoming wavefront into quantitative measurements.

In this project, the focus will be on advancing the development and application of neutron propagation-based phase contrast imaging. A particular emphasis will be placed on exploiting intense broad-spectrum cold neutron source, which provides a higher integral flux compared to monochromatic radiation and thus opens the door to potential in-situ investigations of material processes. Phase effects, arising from spatial variations in the refractive index of the sample, enhance edge definition when in near field regime and improve the visibility of weakly attenuating structures. These capabilities are especially valuable for the non-destructive investigation of complex materials, where absorption contrast alone is insufficient, as well as for advancing the resolution and detectability of fine structural features. This work will also lay the foundation for the practical implementation of high-resolution phase-contrast tomography, enabling 3D characterization based on cold neutron imaging.

Activities of the trainee

This work will focus on:

1. Experimental design and implementation of neutron imaging under varying collimation ratios, in order to investigate how it affect image contrast.
2. Quantitative analysis of the trade-off between optimized phase contrast and integration time, with a focus on weakly absorbing materials.
3. Development and implementation of phase retrieval approaches, enabling the reconstruction of projected phase maps from propagation-based measurements.
4. Preparation for tomographic applications, extending 2D phase-contrast imaging towards full 3D characterization.

Level required

4, 5 year university studies in Physics; Material Science; Materials Engineering

Language skill

As an international research centre, we are particularly keen to ensure that we also attract applicants from outside France. You must be able to communicate in English or in French.

Notes

This post is an internship with a maximum duration of 5months

Please send your application directly to the supervisor:

Bratislav Lukic,

email : lukicb@ill.fr

INTERNSHIP Ref. : LSS_03

The Laue Langevin Institute, located in Grenoble, is Europe's neutron source. It provides its user community, consisting of European scientists from all disciplines, with neutron beams and appropriate instruments to solve questions about the structure and dynamics of materials at scales ranging from tenths of nanometers to several hundred nanometers. Among the techniques it offers, BioSANS allows for the analysis of the structure of biological molecules.

To facilitate the planning and analysis of BioSANS data, a scientific software called Pepsi is currently available via command-line and through an older web interface, accessible at pepsi.app.ill.fr.

Activities of the trainee

We are looking for a motivated student to:

1. Develop a modern web interface to control the command-line application.
2. Provide an interactive 3D and 2D interface.
3. Ensure security aspects.
4. Provide continuous integration using GitHub/GitLab.
5. Design a desktop client offering a comparable interface, compatible with Linux.

The goal is to make the application more accessible and user-friendly, both via a browser and within our analysis infrastructure.

The candidate should have the necessary skills in:

• Programming and
• Web interface development.

Additionally, they should demonstrate:

• Scientific openness to understand the purpose of their work.
• Strong autonomy.
• Good organizational and communication skills to interact with the multiple stakeholders involved in this project.

During the 6-month internship, the candidate will gain enriching experience in a culturally and scientifically diverse environment, along with a stipend ranging from 750 to 900 euros per month (depending on education level).

The internship will take place at ILL, with possible visits to the LJK UGA laboratory. The project will be supervised by:

• Anne Martel, ILL Instrument Scientist.
• Erwan Le Gall, ILL, IT Team Leader.
• Sergei Grudinin, LJK UGA, Developer of the Pepsi model, https://grulab.imag.fr

Level required

5 year university studies in Computing

Language skill

As an international research centre, we are particularly keen to ensure that we also attract applicants from outside France. You must be able to communicate in English or in French.

Notes

This post is an internship with a maximum duration of 5months

Please send your application directly to the supervisor:

Anne Martel,

email : martel@ill.fr

INTERNSHIP Ref. : THEORY_01

Fluid lipid bilayers are the building blocks of biological membranes. The local dynamics of lipid molecules in membrane bilayers have recently been described using the dynamical Matryoshka model (dMm), which employs a nested hierarchical convolution of motional processes derived from quasi-elastic neutron scattering (QENS) experiments. However, the current dMm framework is no longer applicable to more complex lipid arrangements forming non-bilayer phases. Such lipid phases are observed in functional thylakoid membranes and the inner mitochondrial membranes that display highly dynamic lipid polymorphisms: the lamellar (bilayer) phase, the non-bilayer lipid phases such as inverted hexagonal (HII) or isotropic phases (I) [1, 2].

The main objectives of the internship are to extend the current Matryoshka model to describe local dynamics of lipid molecules in non-bilayer lipid phases, namely, in inverted hexagonal (HII) or isotropic phases (I).

Activities of the trainee

1. Inventory review of local motions of lipid molecules in non-bilayer lipid phases;
2. Theoretical calculations of the incoherent neutron structure function (ISF) for non-bilayer lipid phases;
3. Use the derived ISF to experimental QENS data on DOPC:DOPE mixtures, mimicking membrane polymorphism.

Level required

4 year university studies in Physics & Biophysics

Language skill

As an international research centre, we are particularly keen to ensure that we also attract applicants from outside France. You must be able to communicate in English or in French.

Notes

This post is an internship with a maximum duration of 3 à 5months

Please send your application directly to the supervisor:

Dominique Bicout,

email : bicout@ill.fr