Nuclear radii of ^17,19B and ¹⁴Be

The interaction cross sections (σ_I) of light radioactive nuclei close to the neutron drip line (^17,19B, ¹⁴Be) have been measured at around 800 A MeV. The effective root-mean-square (r.m.s.) matter radii of these nuclei have been deduced from σ_I by two different methods, a Glauber-type calculation based on the optical limit approximation and a few-body reaction model. The deduced radii from both approaches agree with each other within experimental uncertainty. The r.m.s. radii of ¹⁷B (2.99 ± 0.09 fm) and of ¹⁴Be (3.10 ± 0.15 fm) in this work are consistent with the previously determined values, and have a higher accuracy. The r.m.s. radius of ¹⁹B (3.11 ± 0.13 fm) was newly determined. Assuming a "core plus 2n" structure in ¹⁷B and ¹⁴Be, the mixing of ν(2s_1/2) and ν(1d_5/2) was studied and the s-wave spectroscopic factor is found to be 36 ± 19%. and 47 ± 25%, respectively. A valence radius analysis suggests a "core plus 4n" structure in 19B.