  We study the minimizers of the Ginzburg-Landau energy functional with a
constant magnetic field in a three dimensional bounded domain. The functional
depends on two positive parameters, the Ginzburg-Landau parameter and the
intensity of the applied magnetic field, and acts on complex valued functions
and vector fields. We establish a formula for the distribution of the
$L^2$-norm of the minimizing complex valued function (order parameter). The
formula is valid in the regime where the Ginzburg-Landau parameter is large and
the applied magnetic field is close to the second critical field---the
threshold value corresponding to the transition from the superconducting to the
normal phase in the bulk of the sample. Earlier results are valid in $2D$
domains and for the $L^4$-norm in $3D$ domains.
