A chara, – Could it be that the Gran Sasso scientists, who suspect they may have found something which travels faster than the speed of light, have been simply observing, albeit from afar, the speed at which the Irish economy has been catapulted into the abyss? – Is mise,
Sir, – Alison Hackett (September 27th), with tongue in cheek, asks if a neutrino can be tagged? So how are they doing it? Taking nothing away from the sophistication and complexity of this work, the principle is simple. The neutrinos are generated from 10 nanosecond bursts of protons accelerated to 400 GeV (gigaelectron volts), fired at a two-meter-thick graphite target. This generates charged mesons, which decay to neutrinos in flight along a one-kilometre tunnel.
Clearly there is no way to know which proton caused which event at the neutrino detector 700 kilometers away; however, the shape of the wave of the proton burst can be compared to the detector arrival burst and mathematically “normalised” to give the flight time of the neutrinos. – Yours, etc,