In type I X-ray bursts (XRBs), nuclide⁴²Ti is considered as the end-point of the (α,p) process. Therefore, the determination of the thermonuclear⁴²Ti(p,γ)⁴³Vreaction rate becomes very important in the understanding of the heavy nuclides synthesis. In the previous work, this reaction rate was calculated entirely based on the theoretical models. The predicted level structure and proton separation energy (S_p) can cause a significant uncertainty in the rate estimated. 

Researchers at Institute of Modern Physics, Chinese Academy of Sciences (IMP) have re-evaluated the thermonuclear⁴²Ti(p,γ)⁴³Vreaction rate (including resonant and non-resonant rates) mainly based on the recently measured⁴³V mass at CSR/Lanzhou, together with the model calculations. The uncertainty of the calculated new rates has been explicitly given. The new rates have been utilized in the one-zone postprocessing XRB model, and the astrophysical impact was revealed. The present work has been accomplished under a close international collaboration. 

Figure 1 shows the presently calculated thermonuclear⁴²Ti(p,γ)⁴³Vreaction rates, with the recent precise proton separation energy of⁴³V (S_p= 83±43 keV) measured at CSR, and with the old AME predicted value (S_p= 90±200 keV). It shows that the uncertainty of the new rate is much smaller than the old one. The astrophysical impact of the new rates has been investigated through one-zone postprocessing XRB calculations. It shows that the new experimental value of S_psignificantly affects the yields of species between mass A»40-45. As well, the precision of the recent experimental S_pvalue constrains these yields to better than a factor of three. This work clearly demonstrates the importance of precise mass measurements to the nuclear astrophysics studies. 

The result has been published inPhys. Rev. C89 (2014) 035802. 

Fig. 1 Total reaction rate calculated for the⁴²Ti(p,γ)⁴³V reaction (in units of cm³mole^-1s^-1). The upper and lower limits of the present rate (with S_p= 83±43 keV) are shown by the red thicker lines, and the previous rates (with S_p= 90±200 keV) are shown by the black thin lines.(Image by IMP)  

Fig. 2 Abundances following one-zone XRB calculations. Abundance variations determined using the present⁴²Ti(p,γ)⁴³V forward rate with reverse rates calculated using∆S_p= 43 keV (IMP new value, solid black line), and∆S_p= 233 keV (AME03 old value, dotted grey line) are indicated. As well, abundances determined using the rates are alsoshown for comparison.(Image by IMP)