An advanced particle detector for the study of ultrahigh-energy collisions of positrons and electrons developed originally at the Lawrence Berkeley Laboratory. The underlying physics of the scattering process can be studied through precise measurements of the momenta, directions, particle species, and correlations of the collision products. The time-projection chamber (TPC) provides a unique combination of capabilities for these studies and other problems in elementary particle physics by offering particle identification over a wide momentum range, and by offering high resolution of intrinsically three-dimensional spatial information for accurate reconstruction of events.