Domain, Specialties : Physique nucléaire
Keywords:
Particle transport, variance reduction technics, AMS
Research Unit : DPhN / LEARN
Summary
The objective of this internship is to extend the variance reduction method called AMS (such as a particle that is pushed towards a detector) to the case of the study of correlated rare events, i.e. to the multi-particle/multi-detector case. These developments will be carried out in the Monte Carlo Geant4 code developed by CERN and will be used by several scientific communities such as medical, space, nuclear and particle physics.
Full description
Tutors :
Loic Thulliez, 01 69 08 56 02
Eric Dumonteil, 01 69 08 56 02
The Monte Carlo simulation of particle transport has become central in many fields such as fundamental physics, medical physics or space applications just to name a few. In order to overcome the computation time inherent to this method, so-called “variance reduction” techniques are developed, whose objective is to “push” the particles towards the detector(s) without inducing bias on the computation results. Recently, a variance reduction method called Adaptive Multilevel Splitting (AMS) [1,2], which focuses on rare events, has been designed and implemented in different calculation codes, such as the Monte Carlo code TRIPOLI4 developed at CEA or the Monte Carlo code Geant4 developed at CERN by an international collaboration. This method offers very interesting perspectives because it allows to preserve the correlations between the particles contributing to the measurement, which is not possible with standard variance reduction technics such as Importance Sampling.
This internship topic proposes to evaluate the interest of this approach in the context of fundamental physics, where simulations seek to detect rare events, as for example in experiments aiming to reveal dark matter or double beta decay without neutrino emission. Indeed, these experiments regularly use coincidence detection methods to increase the signal-to-noise ratio (as an example, one can imagine the detection of a neutron in detector A and a photon in detector B). They represent a challenge in terms of numerical calculation because their simulation requires the sampling of an often-prohibitive number of events (so that a very small fraction of them contribute to the measurement).
The subject of this internship is therefore to use the AMS implemented in the Geant4 code and to optimize its parameters in so-called “multi-particle/multi-detector” configurations, in order to be able to simulate rare correlated events. The trainee will have to finalize the developments already undertaken and to verify their efficiency on different simple representative physical cases. Experimental benchmarks could also be considered using simple detection devices available in the laboratory. This work could eventually lead to a PhD thesis. It will be based at the CEA Saclay center (Orme des Merisiers).
Location
Saclay
Internship conditions
- Internship duration: 6 months
- Level of study: Bac+5
- Training: Master 2
- Continuation in PhD thesis: Yes
- Application deadline: 1 février 2023
Experimental skills
Language : English
Useful methods and technics:
• Physics master student (eg fundamental physics, particle physics, nuclear physics, neutronics)
• Knowledge in nuclear and particle physics, quantum mechanics, neutronics
Computer languages and software:
C++, Python,
ROOT (est un plus), Geant4 (est un plus)
Links
Site web du laboratoire : https://irfu.cea.fr/Phocea/Vie_des_labos/Ast/ast_groupe.php?id_groupe=498