Speaker
Description
An active-target time-projection chamber (TPC) was developed by the University of Warsaw, in collaboration with University of Connecticut and ELI-NP/IFIN-HH, to measure nuclear reactions of astrophysical interest[1,2]. The experimental program focuses on the study in the laboratory ($\gamma$,p) and ($\gamma$,$\alpha$) reactions which are the time reversal of (p,$\gamma$) and ($\alpha$,$\gamma$) that regulate nucleosynthesis in stars. In particular, the benchmark reaction is $^{12}$C($\alpha$,$\gamma$)$^{16}$O, which regulates the carbon-to-oxygen ratio.
The methodology takes advantage of high-intensity monochromatic and collimated gamma beams available today at the High Intensity Gamma-Ray Source (HI$\gamma$S) facility, TUNL, Durham, NC, USA. The employed active-target TPC technique is characterized by a 4p solid angle coverage, which allows to reconstruct in 3D the momenta and angular distributions of the charged reaction products of photo-disintegration reactions. Different reactions can be studied by tuning composition and density of the gaseous target for particular energy of the gamma beam.
In 2022 two experimental campaigns were carried out to study $^{16}$O and $^{12}$C photodisintegration reactions using low-pressure CO$_2$ gas target and monochromatic gamma-ray beams produced at the HI$\gamma$S facility with beam energies ranged from 13.9 MeV down to 8.51 MeV (i.e., nominal center-of-mass energies from 6.7 MeV down to 1.35 MeV, respectively). In the presentation I will discuss detector design, methods of track reconstruction, in-situ detector energy scale calibration and highlights from preliminary results. The prospects for future measurements at energies down to 1 MeV in the center-of-mass will be given.
[1] M. Kuich et al., “Active target TPC for study of photonuclear reactions at astrophysical energies,” Acta Phys. Pol. B, Proc. Suppl., 16, 4-A17 (2023).
[2] M. Ćwiok et al., “Studies of photo-nuclear reactions at astrophysical energies with an active-target TPC,” EPJ Web of Conferences, 279, 04002 (2023).
