Precision calculation of ⁴,⁶,⁸He isotope shifts

Standard perturbation theory is employed to calculate the mass shifts of the 2 1 S 0 -2 3 S 1 and 2 3 S 1 -2 3 P J transitions for 4,6,8 He. High-precision results are obtained for the mass shifts in the isotope pairs 6 He- 4 He and 8 He- 4 He, with uncertainties below 1 part per million (ppm). Our analysis provides a complete set of isotope shift results and systematically examines their sensitivity to nuclear charge radius differences. Once experimental measurements reach a precision comparable to that of the calculated mass shifts, the squared differences of nuclear charge radii can be determined with an accuracy of approximately 0.4%~0.6%, representing an order-of-magnitude improvement over current values.