Reflections in KLOE's 50,000 wires
28 April 1999
A wide-angle lens captures the huge cylindrical volume of the tracking chamber built for KLOE - a detector to study the subtle difference between matter and antimatter that appears in the decays of uncharged particles known as kaons. In particular, KLOE must be able to identify charged particles that are produced when the neutral kaons (which leave no tracks) decay. The tracking chamber reveals the paths of charged particles when they ionise the helium gas that the chamber contains. Wires - seen glinting here - are strung the length of the chamber to pick up electrical signals due to the ionisation.
The lifetime of the neutral kaon varies (as in all particle decays) and so too does the length of its invisible path. To be sure of capturing the longer decays, the tracking chamber (a "drift chamber") is 4 m in diameter and 3.5 m long, and is threaded by some 50,000 wires. This image shows the chamber during construction. Now, with other parts of the detector, it surrounds the beam pipe at Dafne, Italy's new electron-positron collider at the Laboratori Nazionali di Frascati. The electron and positron (antielectron) beams collide head on at the centre of the chamber where they form a particle called the "phi", which itself decays very quickly, often making neutral kaons.
Credit: KLOE experiment
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