Enter the DRAGON: Investigating the 13C(ρ,γ)14N reaction & Using GEANT to test the DRAGON's acceptance



The 13N(p,γ)14O reaction is important as it determines the breakout from the CNO cycle to the HCNO cycle. Studying the 13C(ρ,γ)14N reaction was important for the DRAGON facility at TRIUMF for their future analysis of the 13N(p,γ)14O reaction, not only because pure radioactive ion beams of 13N are impossible to create without contamination from 13C due to the very small mass difference between these two elements, but also it was a good test for the DRAGON due to the fact that the 13C(p,γ)14N reaction has been measured before.

Early analysis of the 13C(p,γ)14N reaction data collected by DRAGON, showed that not all the 14N recoils made it through the DRAGON separator to the end detector (an ionization chamber), because they were being clipped due to the large cone angle for this reaction. A GEANT simulation of DRAGON was used to simulate the 13C(p,γ)14N reaction so that it could be compared to see what fraction of the recoils were being lost within the DRAGON due to this clipping, and also to see where the clipping occurred.

The creation of an ionization chamber in the GEANT simulation for the first time, meant that simulations of the 13C(p,γ)14N reaction could test the DRAGON’s acceptance also, by simulating different mistunes of the DRAGON’s reference tune, in x and y position, x and y angle, and percentage of energy. These mistunes showed that the maximum acceptance for DRAGON is achieved when the beam is not mistuned in x and y position, but mistuned to -0.5% of the energy, and -1.5 mrad and -0.5 mrad in the x and y angular position respectively. They also showed that there is a large acceptance loss, with the maximum acceptance being roughly 78-79%.

Author: Bebington, A. M.