Experimental investigation of the effect of ionization on the 51V(p,n)51Cr reaction

The investigation of the effects of average atomic ionization on nuclear reactions is of prime importance for nuclear astrophysics. No direct experimental measurement using a plasma target has been done yet. In this regard, we measured for the first time the neutron production of a (p,n) reaction in different states of ionization. The studied nuclear reaction was 51V(p,n)51Cr. We measured a significantly lower neutron production than expected when the target was ionized, even when taking into account existing electron screening theory or the effect of the stopping power in the target on the injected proton beam. This experiment is a first step in the process to characterize the influence of ionization at astrophysically relevant energies.Comment: 20 pages, 10 figures, submitted to EP

A new high-precision upper limit of direct α-decays from the Hoyle state in 12C

International audience; The Hoyle state in 12C(Ex = 7.654MeV) is characterized by a pronounced 3α cluster configuration. It is involved in the so-called 3α process in stars, that is responsible of 12C nucleosynthesis. We studied the decay path of the Hoyle state by using the 14N(d, α2)12C(7.654) reaction at 10.5MeV incident energy. We found, with a precision higher of a factor 5 than any other previous experiment, an almost total absence of direct decays by-passing the ground state of 8Be. A new upper limit of such a decay width is placed at 0.043% (95% C.L.). Astrophysical 3α process reaction rate calculations have to be consequently revised

Cardiopoietic cell therapy for advanced ischemic heart failure: results at 39 weeks of the prospective, randomized, double blind, sham-controlled CHART-1 clinical trial

Cardiopoietic cells, produced through cardiogenic conditioning of patients' mesenchymal stem cells, have shown preliminary efficacy. The Congestive Heart Failure Cardiopoietic Regenerative Therapy (CHART-1) trial aimed to validate cardiopoiesis-based biotherapy in a larger heart failure cohort

Influence of electronic environment on nuclear reaction rates

Electron screening has been studied in the 1H(7Li,$\alpha$)4He fusion reaction at lithium beam energies from 0.34 to 2.07 MeV for hydrogen-implanted Pd, Pt, Zn and Ni targets. A large electron screening has been observed in all the targets. However, no large electron screening has been observed in the following proton-induced reactions: 55Mn(p,$\gamma$)56Fe, 55Mn(p, n)55Fe, 113Cd(p, n)113In, 115In(p, n)115Sn, 50V(p, n)50Cr and 51V(p,$\gamma$)52Cr. Moreover, no shift in the resonance energy for the metallic compared to the insulator environment has been observed within our uncertainties for the studied (p,n) and (p,$\gamma$) reactions. These results raise the question about the validity of the measurements that showed large electron screening potentials in nuclear reactions involving high-Z targets, and point to a dependence of the electron screening potential on the position of the target nuclei in the metallic lattice

Study of the neutron-induced reaction 17O(n, α)14C at astrophysical energies via the Trojan Horse Method

Stellar nucleosynthesis processes are of vital importance for nuclear physics: all the heavy elements are created by neutron capture reactions that take place in stars. To correctly study such reactions the neutron abundance available in the environment must be known, which means that also the so-called “neutron poisons” must be considered. The present work will focus on the reaction 17O(n, α) 14C which removes neutrons from the stellar environment during the s-process. Even though the study of such reactions is of high interest, it still presents several technological problems regarding both the creation and characterization of the neutron beam and the radioprotection of the facility. Therefore, the Trojan Horse Method,an indirect method, has been chosen to study the 17O(n, α) 14C reaction in the energy region of astrophysical interest, from 300 keV in the center-of-mass frame down to zero. In the present work, after briefly recalling the main features of the method and reporting on the state of the art for the reaction cross-section measurements, the latest THM experiment will be presented