Status of the KTeV experiment at Fermilab

The origin of CP violation is one of the fundamental questions of particle physics. Since the first observation of CP violation in 1964, kaon physics has provided the only real window through which to observe this phenomenon. One of the best established methods for studying the origin of CP violation rests in the observation of both KL and KS decays into π+π- and 2π0. If the CKM matrix is indeed the source of CP violation, the parameter je'/je, derived from the double ratio of these decays, is expected to be non-zero. Alternative approaches to the study of direct CP violation have received serious attention over the past decade. According to the Standard Model, rare decay modes such as KL → π0e+e- and KL → π0μ+μ- have direct CP violating amplitudes which are comparable to or larger than their CP conserving and indirect CP violating amplitudes. In addition, the rare decay mode of KL → π0νν-bar is a virtually pure direct CP violating decay with very small theoretical uncertainties. Observation of this mode would allow the cleanest determination of the height of the unitarity triangle, the parameter in the Standard Model which determines the size of all CP violating observables. The KTeV collaboration was formed with the goal of probing the most relevant questions relating to CP violation which are accessible via the neutral kaon system to levels which have not previously been attainable. A new physics program to measure the value of je'/je with unprecedented precision (σ = 1 x 10-4) was approved as E832 in 1992 as the primary goal of the KTeV project. A program to investigate rare CP violating kaon decays, originally approved as E799 in 1988, evolved into another physics program in KTeV: E799-II. The experiment was successfully commissioned in the summer of 1996. (author)