  A precision measurement of the top quark mass m_t is obtained using a sample
of ttbar events from ppbar collisions at the Fermilab Tevatron with the CDF II
detector. Selected events require an electron or muon, large missing transverse
energy, and exactly four high-energy jets, at least one of which is tagged as
coming from a b quark. A likelihood is calculated using a matrix element method
with quasi-Monte Carlo integration taking into account finite detector
resolution and jet mass effects. The event likelihood is a function of m_t and
a parameter DJES to calibrate the jet energy scale /in situ/. Using a total of
1087 events, a value of m_t = 173.0 +/- 1.2 GeV/c^2 is measured.
