  Zero Field Cooling (ZFC) and Field Cooling (FC) protocols are commonly used
to investigate the properties of magnetic nanoparticle systems. For
non-interacting conditions the particle properties are fairly well correlated
with the shape of the ZFC/FC curves. However, that is not the case when
significant dipolar interparticle interactions (DII) are present, what
frequently occurs in experimental samples (e.g. aggregates in biological
systems; or the dried powder often used for the ZFC/FC measurements). The
purpose of this work is to show how the influence of the DII on the ZFC/FC
curves, computed by the volume sample concentration c, can be described in a
general way if scaled by the dimensionless parameter c_0 = 2K/M_S^2; where K
and M_S are the anisotropy and saturation magnetization constants of the
particles, respectively. This scaling parameter, which is straightforwardly
derived from the energy equation governing the system, has an analogous meaning
to the normalization of the external magnetic field H by the anisotropy field
of the particles, H_A = 2K/M_S. We use a Monte Carlo technique to show how
apparently different T_B vs. c curves of various particles types (where T_B is
the blocking temperature), follow the same trend if scaling c/c_0.
