Speaker
Dr
Viviana Mossa
(INFN sez. di Bari - Università degli studi di Bari)
Description
The Big Bang Nucleosynthesis (BBN) describes the production of light nuclides in the first minutes of cosmic time. It started with deuterium accumulation when the Universe was cold enough to allow 2H nuclei to be survived to photo-disintegration.
A primordial deuterium abundance evaluation D/H=(2.65±0.07)×10^(-5) [1] is obtained by merging BBN calculations and CMB analysis obtained by the Planck collaboration. This value is in tension with the astronomical observations on metal-poor damped Lyman alpha systems, according to which D/H=(2.53±0.04)×10^(-5) [2]. The main source of uncertainty on standard BBN prediction of deuterium abundance is actually due to the radiative capture process 2H(p,γ)3He converting deuterium into helium, because of the poor knowledge of its S-factor at BBN energies. A measurement of this reaction cross section is thus desirable with a 3% accuracy in the energy range 10keV<Ecm<300keV [1]. Furthermore a precise measurement of the p+d reaction cross section is crucial for testing ab-initio calculations in theoretical nuclear physics.
Thanks to the low background of the underground Gran Sasso Laboratories (LNGS) and to the experience accumulated in more than twenty years of scientific activity, LUNA (Laboratory for Underground Nuclear Astrophysics) [3][4] has planned to measure the 2H(p,γ)3He fusion cross section in the energy range of interest in 2016.
The experimental procedure for studying this reaction consists of two main phases characterized by two different set up. The former provides for a windowless gas target filled with deuterium at 0.3mbar pressure together with a 4π BGO detector. This high efficiency detector will be used for investigating the energy range between 30keV and 260keV, trying to find a continuation of the previous results obtained by the LUNA collaboration in [5], where the 2H(p,γ)3He cross section was studied in the Solar Gamow peak (2.5keV<Ecm<22keV).
The latter phase, instead, will cover the medium-high energies (70keV<Ecm<260keV) using a High Purity Germanium detector (HPGe). The HPGe high resolution allows the differential cross section of the reaction to be evaluated by using the peak shape analysis.
The aim of the present work is to describe the two experimental set up that will be used in the measurement campaign. Possible cosmological and theoretical nuclear physics outcomes from the future LUNA data will be also discussed.
REFERENCES:
[1] E. Di Valentino et al., Phys. Rev. D 90 (2014) 023543
[2] R. Cooke at al., Astrophys. J. 781 (2014) 31
[3] H. Costatini et al., Rep. Prog. Phys. 72 (2009) 086301
[4] C. Broggini et al., Ann. Rev. Nucl. Part. Sci. 60 (2010) 53
[5] C. Casella et al., Nucl. Phys.,A 706 (2002) 203
Primary author
Dr
Viviana Mossa
(INFN sez. di Bari - Università degli studi di Bari)
