Speaker
Description
Nuclear fusion reactions have very important significance in the area of nuclear astrophysics because they determine the nucleosynthesis of the elements in early stages of the universe and control the energy generation and evolution of stars. The precise knowledge of cross-sections and reaction rates of these nuclear fusion reactions are very important to describe the evolution of universe. There are various reactions which have strong significance in astrophysical aspects but our plan is to perform to experimentally study the 12C+12C fusion reaction at very low energies. This reaction is referred as carbon burning in stellar evolution process. Carbon burning plays a very important role in star which has mass greater than the eight solar mass (M > 8Mʘ). If mass is nearly 8Mʘ, then may end up as white dwarf and if mass is sufficiently larger than the 8Mʘ then it may show core-collapse supernovae.
Direct measurements of 12C+12C fusion cross sections have been performed over a wide range of energies by several researchers, but still the energy of interest for astrophysical purposes (Ecm <2MeV) has so far not been reached by direct measurement. Since the Gamow window for 12C+12C reaction (1-2 MeV) is much lower than its coulomb barrier (Ecm = 6.1 MeV), the direct measurement for this reaction is very challenging because of extremely small cross-sections. This becomes even more complicated owing to the high beam-induced background originating from impurities in target, especially, 1H and 2H. Lots of effort have been devoted to direct measurement of fusion cross section for this reaction, but so far could only go down to Ecm=2.1 MeV. Besides, the resonance which was found at Ecm=2.1 MeV [1] remains questionable.
The indirect Trojan Horse Method was applied [2] to measure the astrophysical S-factor for 12C+12C fusion. A strong rise in astrophysical S-factor was reported at low energies, and also the S-factor at 2.1 MeV does not match with that of Ref. [1]. Subsequently, in Ref. [3], it has been claimed that for 12C+12C, astrophysical S-factor decreases at low energies, in contrast to Ref. [2].
In the light of the above scenario, it has become very important to measure the fusion cross sections of 12C+12C directly at low energies and also reduce the uncertainties of the existing measurements, as much as possible. With the upcoming unique FRENA facility at SINP, we plan to study the 12C+12C reaction at low energies. The off-line works that are needed before going for the actual measurement have been done. The present status of this reaction and the off-line works that we have done so far will be presented.
[1] T. Spillane et al., Phys. Rev. Letts, 98, 122501 (2007)
[2] A. Tumino et al., Nature 557, 687 (2018)
[3] A.M. Mukhamedzhanov et al, 99, 064618 (2019)
| Experimental nuclear physics | 1 |
|---|
