India-based Neutrino Observatory (INO) has proposed to build a 51kton magnetised
Iron Calorimeter (ICAL) in an underground laboratory to be constructed near Madurai,
South India. ICAL is aimed to precisely study the atmospheric neutrino oscillation
parameters and determine the ordering of neutrino masses. ICAL will be built by
stacking 151 layers of 56mm soft iron plates, spanning essentially a lateral area
of 48m$\times$16m. The detector will deploy about 28,800 glass Resistive Plate
Chambers (RPCs) of approximately 2m$\times$2m in area, inserted between the iron
layers. About 3.6million detector channels are required to be instrumented to read
data.

During the detector R\&D phase, many RPC detector stacks were constructed and operated
by the collaboration for prolonged periods of time - several years, mainly studying
long term performance of the RPC detectors. But a magnetised 'miniICAL' was proposed
to be built, essentially exactly of the same design as that of ICAL and also using
same detector components. This was expected to serve the purpose of understanding
the engineering issues in constructing the ICAL, and at the same time provide
important inputs on the ICAL's operating parameters and physics measurement
capabilities. A veto wall is also being planned around the miniICAL, to explore
possibility of building ICAL like detectors on surface or at shallow depths. The
veto wall will be made of extruded scintillator tiles and coupled to SiPMs through
WLS fibres.

The experiment was built using 11 layers of 56mm soft iron plates, spanning a lateral area
of 4m $\times$ 4m. A nominal magnetic field of 1.5Tesla is produced inside the
iron plates, by passing about 900A current through two, 18-turn OFHC copper coils
which are water-cooled. A total of 10 RPCs of about 1.9m $\times$ 1.9m in area
is inserted between the iron layers and readout using the electronics of the same
design as that of ICAL.