  We propose a large-area, cost-effective Muon Telescope Detector (MTD) for the
Solenoidal Tracker at RHIC (STAR) at mid-rapidity and for the next generation
of detectors at a possible electron-ion collider. We utilize Multi-gap
Resistive Plate Chambers with large modules and long readout strips (Long-MRPC)
in the detector design. The results from cosmic ray and beam tests show the
intrinsic timing and spatial resolution for a Long-MRPC are 60-70 ps and
$\sim1$ cm, respectively. The prototype performance of such a novel muon
telescope detector at STAR indicates that muon identification at the transverse
momentum of a few GeV/$c$ can be achieved through the combined information of
track matching with the MTD, ionization energy loss in the Time Projection
Chamber, and time-of-flight measurements. A primary muon over secondary muon
ratio of better than 1/3 can be achieved. This provides a promising device for
future quarkonium programs and primordial dilepton measurements at RHIC.
Simulations of the muon efficiency, the signal-to-background ratio of $J/\psi$,
the separation of $\Upsilon$ 1S from 2S+3S states, and the electron-muon
correlation from charm pair production in the RHIC environment are presented.
