  In the framework of linearized non-minimal supergravity (20/20), we present
the embedding of the $R + R^2$ model and we analyze its field spectrum. As
usual, the auxiliary fields of the Einstein theory now become propagating,
giving rise to additional degrees of freedom, which organize themselves into
on-shell irreducible supermultiplets. By performing the analysis both in
component and superspace formulations we identify the new supermultiplets. On
top of the two massive chiral superfields reminiscent of the old-minimal
supergravity embedding, the spectrum contains also a consistent physical,
massive, vector supermultiplet and a tachyonic ghost, massive, vector
supermultiplet.
