Speaker
Description
Compact binary mergers as Binary Neutron Star Mergers (BNSM) have attracted a lot of attention in recent years as the most likely site for r-process (rapid neutron capture) nucleosynthesis [1] and for the emission of gravitational waves [2]. Recently there has been reported experimental evidence of r-process nucleosynthesis in a BNSM identified as the origin of the gravitational-wave source GW170817 [3]. The nuclear reactions that describe the evolution of such systems involve thousands of nuclides following a complex network of capture and decay processes. Here, the main parameter determining the feasibility of the astrophysical environment to produce heavy elements by the r-process is the neutron-to-seed ratio (existing nuclei in the onset of the r-process, like $^{12}$C). In this context, the three-body capture reaction $^4$He($2n,\gamma$)$^6$He are expected to be important in producing $^{12}$C, thus playing a relevant role [4].
As part of a possible path to synthesize $^{12}$C, a low mass seed nucleus of the r process, the collaboration has proposed the measurement of the $^4$He($2n,\gamma$)$^6$He reaction rate at the TriSol facility of the NSL laboratory at the University of Notre Dame [6,7]. The experimental approach adopted consists of measuring the Coulomb breakup channel in collisions of the system $^6$He$+^{208}$Pb, that is, the $^6$He($\gamma,2n$)$^4$He reverse reaction, applying the theoretical framework described in [7], which was developed by members of the collaboration.
The experiment was performed in June 2013. The energy of the $^6$He beam was 19.3 MeV. The detection system was composed of six silicon telescopes available at NSL placed at forward angles (11 $^\circ$ < $\theta_{lab}$< 25 $^\circ$). A 1.7 mg/cm$^2$ thick self supported enriched target of $^{208}$Pb, made by the collaboration at the target laboratory in the University of Lisbon-LIP, was used. More details about the experimental setup and preliminary results of the undergoing data analysis of the experiment will be presented in this talk.
Acknowledgement: This research has been partially supported by Dgapa-Papiit IG101423 project
[1] Astrophys. J. 807, 115 (2015)
[2] Phys. Rev. Lett. 116, 061102 (2016)
[3] Nature 551, 67–70 (2017)
[4] Phys. Rev. C 74, 015802 (2006)
[5] NIM A 1047 (2023) 167784
[6] NIM B 541 (2023) 216-220
[7] Phys. Rev. C 93 (2016) 041602(R).
