Research Projects

The baryonic mater which is the product of Big Bang nucleosynthesis in the form of hydrogen, helium and very small amount of lithium, beryllium and boron, are the seed material that has fueled the chemical evolution of our Universe. It has been already established in nuclear astrophysics community that ¹²C is mostly formed by 3α process in our universe but a small amount of ¹²C is also produced through the reaction ¹¹B(p,γ)¹²C. Though, tens of thousands of nuclear reactions can participate in a specific nucleosynthesis scenario, depending on the various environmental conditions, still only a small fraction of these reactions have a strong impact on the overall chemical evolution of the elements. Keeping this in mind, we have chosen the capture reaction ¹¹B(p,γ)¹²C for a thorough experimental investigation and to determine the more accurate reaction rate. This constitutes the first part of this present research proposal. According to the standard stellar models, the globular clusters (GC) are the oldest objects and considered to be the first structures of our galaxy. They can provide the information about the lower age limit of our universe. It was speculated that the coeval stars of the globular clusters, which were formed from a homogeneous reservoir of primordial gas, would have the same metallicity. But these models are facing a big question after some recent observations of globular clusters with high resolution spectrometers which show a large scattering of C, N,O, Na, Mg elements in those coeval stars,which were formed from a homogeneous reservoir of primordial gas. Observations also indicate about the existence of anticorrelations between Na-Al and O-Na and Mg-Al nuclei for each subset of stars, based on their iron content, in the GC. The Na+p reaction which is a bridge between NeNa and MgAl cycles of hydrogen burning phase plays a central role in the O-Na anticorrelationbecause it destroys ²³Na through the reactions ²³Na(p,γ)²⁴Mg and ²³Na(p,α)²⁰Ne.Thus, a proper estimation of reaction rates of ²³Na(p,gamma)²⁴Mg and the competing ²³Na(p,alpha)20Ne reaction are required for profiling the chemical structures of the stars in the GCs. Since the first attempt by Fowler et al., in 1975, efforts are on to reduce the uncertainty in the reaction rate of ²³Na(p,gamma)²⁴Mg capture reaction at relevantastrophysical temperatures. Aiming to investigate the uncertainty sources and to finally reduce the uncertainty in the reaction rate further, the reaction has been chosen as the second system for an experimental investigation in our project. The proposed experiments will be performed using the low energy facilities at TIFR in Mumbai and at the upcoming Facility for Research in Experimental Nuclear Astrophysics (FRENA) at Saha Institute of Nuclear Physics, Kolkata. The measured cross sections in the relevant energy window will be used as input to the R-matrix modeling for the estimation of reaction rate.