Neutron spectroscopy from 1 to 15 MeV with Mimac-FastN, a mobile and directional fast neutron spectrometer and an active phantom for BNCT and PFBT

In the frame of direct dark matter search, the fast neutrons producing elastic collisions on the nuclei of the active volume are the ultimate background. The MIMAC (MIcro-tpc MAtrix Chambers) project has developed a directional detector providing the directional signature to discriminate them from the searched events based on 3D nuclear tracks reconstruction. The MIMAC team of the LPSC has adapted one MIMAC chamber as a mobile fast neutron spectrometer, the Mimac-FastN detector, having a wide neutron energy range (10 keV – 600 MeV) working with different gas mixtures and pressures. This presentation will be focused on the MeV range with 4He + 5% CO2 gas mixture at 700 mbar. A boron coating inside the active volume used for calibration purpose opens the possibility to use the active volume as an active phantom for Boron Neutron Capture Therapy (BNCT) and Proton Fusion Boron Therapy (PFBT).

New theoretical results for radiative 3H(p,γ)4He, 3He(2H,γ)5Li, 4He(2H,γ)6Li, 4He(3H,γ)7Li and 4He(3He,γ)7Be captures at astrophysical energies

We have studied the proton capture reaction [Formula: see text]. It plays a role in the nucleosynthesis of primordial elements in the early Universe leading to the prestellar formation of [Formula: see text] nuclei. All results of our researches and more new data from works show that the contribution of the [Formula: see text] capture reaction into the processes of primordial nucleosynthesis is relatively small. However, it makes sense to consider this process for making the picture complete for the formation of prestellar [Formula: see text] and clearing of mechanisms of this reaction. Furthermore, we have considered the [Formula: see text] reaction in the low energy. This reaction also forms part of the nucleosynthesis chain of the processes occurring in the early stages of formation of stable stars. They are possible candidates for overcoming the well-known problem of the [Formula: see text] gap in the synthesis of light elements in the primordial Universe. Continuing the study, we have considered the radiative capture [Formula: see text] at superlow energies, which has a undeniable interest for nuclear astrophysics, since it takes part in the proton–proton fusion chain, and new experimental data on the astrophysical [Formula: see text]-factors of this process at energies down to 90 and 23[Formula: see text]keV and data on the radiative capture reaction [Formula: see text] down to 50[Formula: see text]keV appeared recently. Moreover, radiative capture reactions [Formula: see text] and [Formula: see text] may have played a certain role in prestellar nucleosynthesis after the Big Bang, when the temperature of the Universe decreased to the value of [Formula: see text].

Fusion in the Sun

Protons in the Sun’s core are a dense plasma allowing fusion events where two protons initially join to produce a deuteron. Eventually this leads to alpha particles, the mass-four nucleus of helium, releasing kinetic energy. Schrodinger’s equation allows particles to penetrate classically forbidden Coulomb barriers with small but important probabilities. The approximation known as Wentzel–Kramers–Brillouin (WKB) is used by Gamow to predict the rate of proton–proton fusion in the Sun, shown to be in agreement with measurements. A simplified formula is given for the power density due to fusion in the plasma constituting the Sun’s core. The properties of atomic nuclei are briefly summarized.