and the SNR emissions, which is crucial to accurately determine the spectral properties of G326.3$-$1.8 and understand its nature.]{} [The centroid of the $\gamma$-ray emission evolves with energy and is spatially coincident with the radio PWN at high energies (E $>$ 3 GeV). The morphological analysis reveals that a model considering two contributions from the SNR and the PWN reproduces the $\gamma$-ray data better than a single-component model. The associated spectral analysis using power laws shows two distinct spectral features, a softer spectrum for the remnant ($\Gamma$ = 2.17 $\pm$ 0.06) and a harder spectrum for the PWN ($\Gamma$ = 1.79 $\pm$ 0.12), consistent with hadronic and leptonic origin for the SNR and the PWN respectively. Focusing on the SNR spectrum, we use one-zone models to derive some physical properties and, in particular, we find that the emission is best explained with a hadronic scenario in which the large target density is provided by radiative shocks in H[i]{} clouds struck by the SNR.]{}

Introduction
============

Supernova remnants (SNRs) and pulsar wind nebulae (PWNe) have long been considered potential sources of Galactic cosmic rays and have therefore been investigated over a wide range of energies. In SNRs, the fast shock wave 