Recherche
Le groupe Physique nucléaire et des particules (NPP) exploite plusieurs instruments et installations proposés dans le cadre du programme utilisateurs : deux instruments (PN1, spectromètre de fission « LOHENGRIN », et « FIPPS », spectromètre gamma) relèvent principalement de la physique nucléaire et de ses aspects appliqués. Trois autres (PF1, installation de faisceau intense de neutrons froids, PF2 et SuperSUN, installation de neutrons ultrafroids) couvrent principalement la physique des particules avec des neutrons.
Le groupe a en outre la responsabilité de l’interféromètre à neutrons thermiques (S18), exploité comme instrument CRG, et de l’instrument de la collaboration RICOCHET, installé à l’ILL.
Le film a été présenté à la conférence de l’American Physical Society en mars 2017.
FIPPS is ILL's gamma-ray spectrometer for thermal-neutron-induced reactions. It is composed of a highly collimated halo-free pencil neutron beam impinging on a stable or radioactive target surrounded by a high resolution high-purity germanium detectors array.
PF1B provides the strongest polarised and unpolarised cold neutron beam in the world currently available for particle and nuclear physics (2x10^10 neutrons/(cm^2.s); the guide cross section is 6x20 cm^2).
Some of the experiments just use PF1B neutron beam, other profit from its many devices needed to polarise, form, characterise, shield or remove the neutron beam.
The ultracold neutron facility PF2 was built by TU Munich in collaboration with ILL. It provides a density of 50 cm^-3 of ultracold neutrons (UCN) with speeds less than 6 m/s. UCN are produced at the top end of a vertical guide where neutrons with speeds of 50 m/s are converted by the so-called Steyerl turbine into UCN. The UCN are then led by horizontal guides to several experiments in parallel. There is also an output for very cold neutrons (VCN) with a wavelength of 100Å. The fact that neutron are electrically neutral makes it possible to store UCN in traps. The majority of the measurements carried out at PF2 use this feature.
LOHENGRIN is a recoil mass spectrometer for studying the properties of the exotic isotopes produced during the fission process. It allows us to study the mass, kinetic energy and charge distribution of the products of thermal-neutron-induced nuclear fission at very high resolution.
RICOCHET is an international collaboration aiming to explore the Coherent Elastic Neutrino-Nucleus Scattering (CeνNS), a long-predicted interaction that was observed experimentally only in 2017. A precise measurement of the nuclear recoil spectrum for reactor neutrinos, where the process is fully coherent, could reveal deviations from the Standard Model of particle physics, potentially unlocking the door to new physics.
The CRG instrument S18 is a perfect crystal neutron interferometer which can also be configured as a high resolution Bonse Hart camera. This instrument can be used for precise measurement of neutron scattering lengths and for basic neutron quantum optics studies and related phenomena.
The ultracold neutron source SuperSUN is a density type, superthermal source using isotopically pure 4He at 0.6K as a convertor. The incoming cold neutron beam has a capture flux of about 1010 neutron/cm2^2/ s which is transformed into 3.8 × 106 UCN measured at a reactor power of 48.6 MW at saturation.
