  We present the full description of a measurement of the branching ratios for
the beta-decay of 38Ca. This decay includes five allowed 0+ --> 1+ branches and
a superallowed 0+ --> 0+ one. With our new result for the latter, we determine
its ft value to be 3062.3(68) s, a result whose precision (0.2%) is comparable
to the precision of the thirteen well known 0+ --> 0+ transitions used up till
now for the determination of Vud, the up-down quark-mixing element of the CKM
matrix. The 38Ca superallowed transition thus becomes the first addition to
this set of transitions in nearly a decade and the first for which a precise
mirror comparison is possible, thus enabling an improved test of the
isospin-symmetry-breaking corrections required for the extraction of Vud.
