  Resistive Plate Chambers are used in the ATLAS experiment for the muon
trigger and two coordinate measurements in the central region. In preparation
for the coming years of LHC running at higher luminosity, besides the New Small
Wheel project which is expected to complement the ATLAS muon spectrometer in
the endcap regions, a smaller size project, known as BIS78, is being developed
with a foreseen installation during the LHC Long Shutdown 2. The BIS78 project
will reinforce the fake muon rejection and the selectivity of the muon trigger
in the transition region between the ATLAS barrel and end-caps by adding 32 RPC
triplets on the edges of the Inner Barrel even sectors (BIS7 and BIS8) as this
region is characterized by high rate due to secondary charged tracks generated
by beam halo protons and a lack of detector instrumentation. Due to the narrow
available space, the project foresees to replace the existing Monitored Drift
Tubes, used for the precise position measurement in this area, with muon
stations formed by integrated smaller diameter tubes and a new generation of
RPCs, capable of withstanding the higher rates and provide a robust standalone
muon confirmation. These new RPCs are based on novel design of the gas volume
with a thinner gas gap and resistive electrodes, a lower operating voltage and
new high gain front-end electronics with respect to the legacy RPCs. Besides
the use in Run-3 and onwards, this project is also of particular relevance as a
pilot test for the HL-LHC upgrade when an additional full layer of new RPC
triplets is expected to complement the full barrel region in the innermost
plane. The core of the project is presented, together with a description of the
production and the test results. Details on the detector infrastructure and
services along with a roadmap towards the final installation and commissioning
during the Long Shutdown 2 are also discussed.
