Internship in hierarchical backprojection for tomography of large volumes

Context & Job description

With regard to the scientific challenges of the ESRF and the volume of data created during experiments, our IT teams implement the forefront of information technology solutions and ensure technological surveys.

More recently, the upgrade of our synchrotron has accelerated the IT needs of the different user. Indeed, in 2020, the ESRF started up its EBS (Extremely Brillant Source) making it the first 4th generation synchrotron. The new scientific possibilities offered by this innovation, combined with our new instruments, open up exciting scientific perspectives while increasing the complexity of the data produced by the experiments.

To ensure the optimisation of these data, the ESRF IT teams are engaged in implementing the most innovative solutions covering the entire scope of data management (from data visualisation, processing to algorithms and scientific data analysis to technical IT infrastructure).

The team you will join

We propose you to join the Algorithms and Scientific Data Analysis (ADA) team. The ADA team is responsible for developing algorithms and data-analysis software packages to provide the ESRF users with high-performance computing applications and faster data analysis.

Your mission :

Algorithms for the new helical tomography setups at BM18, and large reconstructed volumes.

Tomography is a non-destructive imaging technique where a sample is scanned with X-rays, and numerical methods are used to obtain a three-dimensional reconstruction of the sample interior.

Tomography has numerous applications in various fields like material science and medical physics.

The developments of helical scan setups for tomography at the new experimental facility BM18 opens new opportunities for improved quality reconstructions of large samples.

The first part of the internship will be devoted to the validation of the reconstruction algorithms by checking the quality of the reconstructions performed from experimental and simulated data, in the presence of different levels of noise and defects in the detector. Defects in the detector/scintillator and/or in the beam profile can be corrected thanks to the redundancy of information, created by the helical trajectory, for any given region of the sample, due to multiple turns. This redundancy can be exploited by creating a tailored "confidence" map. The student will create the "confidence" map using machine learning techniques to identify the faults.

In the second part of the stage the student will test, characterize, and possibly improve, the quality of new reconstruction algorithms which are alternative to the filtered backprojection (FBP) currently implemented. In particular the hierarchical back projection which has a computational complexity (O(n^2*log(n)) vs O(n^3) where "n" is the detector width) and is therefore more suited for handling big data volumes.

The developments can be done at the prototypical level providing feedbacks to, and comparison with the already existing high performance reconstruction pipeline, and tested on the first helical datasets which will be available starting mid-February.

Expected profile

  • You are a student in engineering school or university (4th of 5th year) with a curriculum emphasizing algorithms and their numerical implementations
  • You master the python language and its libraries for numerical calculation.
  • Good oral and written communication skills in English.

You want to join us? Let's apply directly on our website sending your CV and Motivation Letter.

If you need further information on the internship, please contact Alessandro Mirone (mirone@esrf.fr)

Working conditions

The duration of the internship is a minimum of 3 months, the dates and content will be adapted according to the trainee's level of study.

As a trainee, you will receive indemnities which depend on your educational level (5.61€/hour in 2021 which in average resulted in 820€/month).

We offer a trainees indemnities package designed to support your quality of life and your installation in the Grenoble area.

If your school is far from Grenoble, the ESRF can facilitate your housing with a dedicated accommodation allowance (around 300€/month). The ESRF will also provide you with the main housing contacts to find an accommodation.

The ESRF participates in the common restaurant costs.

Company description

The European Synchrotron, the ESRF, is an international research centre based in Grenoble, France.

Through its innovative engineering, pioneering scientific vision and a strong commitment from its 700 staff members, the ESRF is recognised as one of the top research facilities worldwide. Its particle accelerator produces intense X-ray beams that are used by thousands of scientists each year for experiments in diverse fields such as biology, medicine, environmental sciences, cultural heritage, materials science, and physics.

Supported by 22 countries, the ESRF is an equal opportunity employer and encourages diversity.

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