  Proposals for Bell inequality tests on systems restricted by superselection
rules often require operations that are difficult to implement in practice. In
this paper, we derive a new Bell inequality, where pairs of states are used to
by-pass the superselection rule. In particular, we focus on mode entanglement
of an arbitrary number of massive particles and show that our Bell inequality
detects the entanglement in the pair when other inequalities fail. However, as
the number of particles in the system increases, the violation of our Bell
inequality decreases due to the restriction in the measurement space caused by
the superselection rule. This Bell test can be implemented using techniques
that are routinely used in current experiments.
