Reaction Cross Sections for $^{13-15}$B and One-neutron Halo in $^{14}$B

We have measured reaction cross sections (sigma(R)) for B-13,B-14,B-15 on Be, C, Al, and proton targets. In addition to the conventional method of deducing nucleon density distributions based on the Glauber-type calculation, the recently developed method for deducing point- proton and neutron density distributions separately from sigma(R) on proton targets were utilized for these nuclei. The result suggests the necessity for B-14 of a large tail in its neutron density distribution, which can be referred to as a one-neutron halo. Root-mean-square point- proton, neutron and matter radii for B-13,B-14,B-15 were also derived. From present systematic studies for B-13,B-14,B-15, a large enhancement of matter and neutron radii in B-14 was found for the first time.