Speaker
Description
The $\mathrm{^{21}Ne}$(p,$\gamma$)$\mathrm{^{22}Na}$ reaction is expected to be the main producer of the radioactive isotope $\mathrm{^{22}Na}$ ($t_{1/2}$ = 2.602 years) in novae. Novae explosions are the result of a thermonuclear runaway occurring on the surface of a white dwarf accreting material from a less evolved companion star in a close binary system that ejects a significant amount of nuclear-processed material into the interstellar medium. Amongst the isotopes synthesized during such explosions, radioactive nucleus $\mathrm{^{22}Na}$ is specifically produced in white dwarfs made of O and Ne, the progeny of stars with initial mass in the range of 8-10 solar mass. Once produced, $\mathrm{^{22}Na}$ beta decays to an excited state of $\mathrm{^{22}Ne}$, which de-excites by emitting a 1275 keV gamma ray [1]. If detected by satellite telescopes, this signal can provide information on the amount of $\mathrm{^{22}Na}$ produced in novae, and thus place direct constraints on the nucleosynthesis in these explosions.
Predictions of the $\mathrm{^{22}Na}$ abundance in novae strongly depend on the $\mathrm{^{21}Ne}$(p,$\gamma$)$\mathrm{^{22}Na}$ reaction rate. In the novae temperature range (0.2 $<$ $T_{9}$ $<$ 0.5), $\mathrm{^{21}Ne}$(p,$\gamma$)$\mathrm{^{22}Na}$ reaction is dominated by resonances at proton beam energies $\mathrm{E_p}$ = 126 and 272 keV [2]. In this contribution, we will report on the direct and precise measurement of the $\mathrm{E_p}$ = 272 keV resonance strength performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) [3] located at Gran Sasso National Laboratory in Italy, benefiting from the low background conditions. The experimental setup, techniques, and results will also be described in detail in the talk.
References:
[1] M. Hernanz et al., ESA Special Publication 588, 351 (2005).
[2] J. Görres et al., Nuclear Physics A 385, 57-75 (1982).
[3] M. Aliotta et al., Annual Review of Nuclear and Particle Science 72, 177-204 (2022).
