Towards the study of²H(p, γ)³He reaction in the Big Bang Nucleosynthesis energy range in LUNA

Abstract

Abstract. The Big Bang Nucleosynthesis began a few minutes after the Big Bang, when the Universe was sufficiently cold to allow deuterium nuclei to survive photo-disintegration. The total amount of deuterium produced in the Universe during the first minutes depends on the cosmological parameters (like the energy density in baryons, Ω b h 2 , and the effective neutrino number, N ef f ) and on the nuclear cross sections of the relevant reactions. The main source of uncertainty in the deuterium estimation comes from the 2 H(p, γ) 3 He cross section. Measurements of Cosmic Microwave Background (CMB) anisotropies obtained by the Planck satellite are in very good agreement with the theoretical predictions of the minimal ΛCDM cosmological model, significantly reducing the uncertainty on its parameters. The Planck data allows to indirectly deduce with very high precision the abundances of primodial nuclides, such as the primodial deuterium fraction 2 H/H = (2.65 ± 0.07) · 10 −5 (68% C.L.). The astrophysical observations in damped Lyman-α systems at high redshifts provide a second high accuracy measurement of the primodial abundance of deuterium 2 H/H = (2.53 ± 0.04) · 10 −5 (68% C.L.). The present experimental status on the astrophysical S-factor of the 2 H(p, γ) 3 He reaction in the BBN energy range, gives a systematic uncertainties of 9%. Also the difference between ab-initio calculations and experimental values of S12 is at the level of 10%. In order to clarify the actual scenario, a measurement of 2 H(p, γ) 3 He cross section with a precision of a few percent in the 70-400 keV energy range is planned at LUNA in 2016. A feasibility test of the measurement has been performed in October 2014, giving the preliminary results on the cross section. The experimental setup for the test and final measurement campaign will be presented.

Baryon Acoustic Oscillations and the Hubble constant: past, present and future

“…This means that solving the BBN Ω b h 2 discrepancy will play an important role in next generation measurements of H 0 using BAO + BBN. There is hope of better laboratory measurements of the d(p, γ) 3 He reaction rate from the Laboratory for Underground Nuclear Astrophysics (LUNA [58,59]). results, we find probabilities of 1.2% and 1.3% for the tension being statistical in nature.…”