Time Projection Chamber (TPC) detectors for nuclear astrophysics studies with gamma beams

Abstract

Gamma-Beams at the HIγS facility in the USA and anticipated at the ELI-NP facility, now constructed in Romania, present unique new opportunities to advance research in nuclear astrophysics; not the least of which is resolving open questions in oxygen formation during stellar helium burning via a precise measurement of the 12 C(α, γ) reaction. Time projection chamber (TPC) detectors operating with low pressure gas (as an active target) are ideally suited for such studies. We review the progress of the current research program and plans for the future at the HIγS facility with the optical readout TPC (O-TPC) and the development of an electronic readout TPC for the ELI-NP facility (ELITPC).

Highlights of the day-one experimental program at the gamma-beam system of ELI-NP

“…The mirror alpha capture reactions 3 H( α , γ ) 7 Li and 3 He( α , γ ) 7 Be have been at odds in the last five years as the different theoretical models agree very well with the 3 He( α , γ ) 7 Be experimental cross section but could not reproduce the 3 H( α , γ ) 7 Li experimental results. A study of the 16 O( γ , α ) 12 C will help understanding He burning in massive stars.…”

“…The cross section of the time-reversal 12 C( α , γ ) 16 O reaction has been measured down to energies around 1 MeV but must be extrapolated to helium-burning energies around 300 keV. There are two energy ranges, which are important for the study of the 12 C( α , γ ) 16 O cross section, at energies below 1 MeV to approach the Gamow peak or at higher energies to constrain the R-matrix extrapolation.…”

“…The cross section of the time-reversal 12 C( α , γ ) 16 O reaction has been measured down to energies around 1 MeV but must be extrapolated to helium-burning energies around 300 keV. There are two energy ranges, which are important for the study of the 12 C( α , γ ) 16 O cross section, at energies below 1 MeV to approach the Gamow peak or at higher energies to constrain the R-matrix extrapolation. Modelling the evolution and explosion of massive stars requires a 10% uncertainty on the 12 C( α , γ ) 16 O reaction cross section but recent analysis of the world data estimated this uncertainty at around 20% [12].…”

“…There are two energy ranges, which are important for the study of the 12 C( α , γ ) 16 O cross section, at energies below 1 MeV to approach the Gamow peak or at higher energies to constrain the R-matrix extrapolation. Modelling the evolution and explosion of massive stars requires a 10% uncertainty on the 12 C( α , γ ) 16 O reaction cross section but recent analysis of the world data estimated this uncertainty at around 20% [12]. The approach for such studies is the measurement of the time-reversal 16 O( γ , α ) 12 C reaction.…”

A Fast Universal Kinematic Fitting Code for Low-Energy Nuclear Physics: FUNKI_FIT

“…Such experiments involve measuring this radiation (charged ions, electrons, neutrons or electromagnetic radiation) and using it to reconstruct the reaction taking place. Charged ions may be detected using silicon-strip detectors or gaseous Time Projection Chambers (TPCs) [1][2][3]. Such devices provide information about the energies and directions of the particles they detect.…”