  The NA61 Experiment at CERN SPS is a large acceptance hadron spectrometer,
aimed to studying of hadron-hadron, hadron-nucleus, and nucleus-nucleus
interactions in a fixed target environment. The present paper discusses the
construction and performance of the Low Momentum Particle Detector (LMPD), a
small time projection chamber unit which has been added to the NA61 setup in
2012. The LMPD considerably extends the detector acceptance towards the
backward region, surrounding the target in hadron-nucleus interactions. The
LMPD features simultaneous range and ionization measurements, which allows for
particle identification and momentum measurement in the 0.1-0.25 GeV/c momentum
range for protons. The possibility of Z=1 particle identification in this range
is directly demonstrated.
