Measurement of the ${}^2\mathrm{H}(d,p){}^3\mathrm{H}$ reaction at astrophysical energies via the Trojan-horse method

The study of the ${}^2\mathrm{H}(d,p){}^3\mathrm{H}$ reaction is very important for the nucleosynthesis in both the standard Big Bang and stellar evolution, as well as for the future fusion reactor's planning of energy production. The ${}^2\mathrm{H}(d,p){}^3\mathrm{H}$ bare nucleus astrophysical $S\left(E\right)$ factor has been measured indirectly at energies from about 400 keV down to several keV by means of the Trojan-horse method applied to the quasifree process ${}^2\mathrm{H}({}^6\mathrm{Li},pt){}^4\mathrm{He}$ induced at a lithium beam energy of 9.5 MeV, which is closer to the zero-quasifree-energy point. An accurate analysis leads to the determination of the $S_{\text{bare}}\left(0\right)=56.7\pm 2.0$ keV b and of the corresponding electron screening potential $U_e=13.2\pm 4.3$ eV. In addition, this work gives an updated test for the Trojan-horse nucleus invariance by comparing with previous indirect investigations using the ${}^3\mathrm{He}=(d+p)$ breakup.

Figure 1

Schematic representation of the Trojan-horse method.

Figure 2

Experiment setup for the ${}^2\mathrm{H}({}^6\mathrm{Li},pt){}^4\mathrm{He}$ reaction.

Figure 3

Selection of the three-body-reaction events of ${}^2\mathrm{H}({}^6\mathrm{Li},pt){}^4\mathrm{He}$ from the $E_1-E_2$ kinematic locus.

Figure 4

Experimental $Q_3$-value spectrum from the selection of Fig. 3 for the kinematic locus of ${}^2\mathrm{H}({}^6\mathrm{Li},pt){}^4\mathrm{He}$. The relevant peak is the one at about 2.5 MeV.

Figure 5

Experimental spectrum of momentum distribution for intercluster motion of $\alpha$ inside ${}^6\mathrm{Li}$ (the blue points and the dotted green line for the fitting curve) compared with the theoretical calculation (the red line).

Figure 6

The $S\left(E\right)$ factor obtained from THM measurement compared with direct data.

Figure 7

Fitting of $S\left(E\right)$ to obtain $U_e$.