Presentation of the group

The fields of activity of the group Nuclear Structure and Energy (SEN) are experimental nuclear physics and nuclear energy. These two fields of study are addressed following two closely related approaches. The first one is essentially computational and related to β decay and reactor physics, while the second one is purely experimental and related to the physics of β decay which has many fields of application. They can be summarised as follows.

Reactor simulations and summation calculations: fundamental and applied neutrino physics, future reactors and decay heat.

 

Historically, the SEN group (formerly ERDRE) of the Subatech laboratory, with its in-depth knowledge of nuclear and reactor physics, first placed its expertise at the service of reactor antineutrino experiments Double Chooz, Nucifer and Solid more recently. Not only is the simulation of a reactor core essential for these experiments, but also the understanding of the nuclear structure and in particular of the beta decay of the fission products responsible for the emission of antineutrinos from reactors is an asset for this type of experiment. From a purely fundamental point of view, it was first of all in the Double Chooz experiments (until the end of 2016) then Solid (still today) that the group was/is co-leader of the reactor working groups and thus provided the fission rates of the two Chooz PWRs and the BR2 reactor of Solid, the predictions of the energy spectra of the antineutrinos produced by the summation method as well as the systematic errors associated with the fission rates of these reactors. These predictions were essential, for example, in the Double Chooz experiment for the determination of the first indication of the mixing angle θ13 published by a reactor neutrino experiment. From a more practical point of view, studies of proliferation scenarios are also carried out in the group. These studies attempt to answer the question posed by the International Atomic Energy Agency: what is the maximum sensitivity that an antineutrino detector can achieve to the composition of the nuclear fuel used in a power plant? The reactor simulations developed by the group have thus been essential in the context of the Nucifer project of interest for non-proliferation. We have also been involved in this experiment through the design and building of the muon veto of Nucifer.

Finally, we also carry out simulation calculations for future reactors and, more recently, we have been carrying out decay heat calculations.

 
 
Fundamental physics of the nucleus: calorimetric measurements associated with the β decay of nuclei of interest for nuclear structure and astrophysics, reactor antineutrinos and decay heat.

The β- decay of a nucleus accompanied by the emission of a pair of leptons (e-/ν) as well as photons resulting from the de-excitation of the daughter nucleus offers several experimental channels to measure its properties. In addition, it offers a wide range of physics domains to be studied, all closely related, around the fundamental physics of the nucleus. In 2009 the group started a project to study the β- decay properties of fission products via the measurement of the gammas emitted. The physics motivations were multiple but originally motivated by the need to perfect our important summation calculations for the prediction of antineutrino spectra emitted by reactors and for the calculation of the decay heat (nuclear reactor safety) based on the nuclear data known to date on fission products. The nuclear structure knowledge present in the group has also made it possible to target the study of very specific nuclei of major interest for nuclear structure and astrophysics. The group is part of the international TAS (Total Absorption Spectroscopy) collaboration which carries out measurements of the β decay properties of fission products with a technique complementary to the Germanium detectors. This technique based on calorimetry is capable of correcting the biases induced by HPGe on the beta decay data.

Moreover, in addition to the nuclear structure experimental program, the SEN team is also involved in nuclear dynamics measurements.

 

 

Currently the group has 6 permanent members, 1 PhD student and 1 post-doc.

The group is part of the international collaboration TAGS et collaborates closely with IFIC in Valencia, with the university of Surrey and with CIEMAT in Madrid for its instrumental projects as well as with international experimental sites as the University of Jyväskylä and the CERN (ISOLDE).

We collaborates nationaly with the maboratories IJCLab in Orsay, LPSC in Grenoble, GANIL in Caen, LPC in Caen, CENBG in Bordeaux, IPHC in Strasbourg and IP2I in Lyon. We also collaborates with the CEA (Cadarache), the LNHB and the CEA DAM (Bruyères-Le-Châtel).

The SEN group is co-funded by CNRS/IN2P3, SUBATECH, the Pays de La Loire region, the research program NEEDS, the University of Nantes, the IMT Atlantique and the european projects SANDA and SAMOSAFER.