  Covariant first and second quantization of the free d=4 massless
superparticle are implemented with the introduction of purely gauge auxiliary
spinor Lorentz harmonics. It is shown that the general solution of the
condition of maslessness is a sum of two independent chiral superfields with
each of them corresponding to finite superspin. A translationally covariant, in
general bijective correspondence between harmonic and massless superfields is
constructed. By calculation of the commutation function it is shown that in the
considered approach only harmonic fields with correct connection between spin
and statistics and with integer negative homogeneity index satisfy the
microcausality condition. It is emphasized that harmonic fields that arise are
reducible at integer points. The index spinor technique is used to describe
infinite-component fields of finite spin; the equations of motion of such
fields are obtained, and for them Weinberg's theorem on the connection between
massless helicity particles and the type of nongauge field that describes them
is generalized.
