Sinervo was a key member of the team that discovered the top quark and led the effort in the early 1990's.
Sinervo studies the heavier quarks. He started with measurements of the lifetime of the charm quark, the excited states of pairs of quarks known as K mesons and then the discovery and study of the top quark, one of the last missing particles in the Standard Model (the other being the hypothesized Higgs boson). His collaborated in the Collider Detector at Fermilab experiment and proved that the top quark existed in March 1995. It turns out to be extremely massive (the mass of a gold nucleus) and is therefore created only rarely in particle annihilations.
He then went on to perform numerous measurements of the top quark, developing new techniques at each step. Together with one of his students, Jean-Francois Arguin, Sinervo developed the most precise method of measuring the top quark mass.
Recently Sinervo has been focusing on the Large Hadron Collider (LHC) as a member of the ATLAS collaboration and the search for the Higgs boson. He was part of the team that presented evidence in 2012 for a new boson, which has all the properties of the elusive Higgs boson originally predicted about 40 years ago as an essential ingredient of the Standard Model of particle physics. Within ATLAS, he continues his studies of the top quark, and uses it to search for very heavy particles produced in the LHC that would decay into top quark pairs.