Recall a few years back, a physics lab in Italy reported
faster than light neutrino observations. After some ado,
they finally diagnosed a dodgy optical interconnect.
How does that result occur? An intermittent interface
would produce a broken signal, or reduced RMS power, or
perhaps data bit errors, if used for communication.
But how does a faulty connection result in a spuriously
high velocity measurement?
On Tue, 7 Jul 2020 19:35:15 -0700 (PDT), RichD...
<r_delaney2001@yahoo.com> wrote:
Recall a few years back, a physics lab in Italy reported
faster than light neutrino observations. After some ado,
they finally diagnosed a dodgy optical interconnect.
It was explained to me by an engineer from CERN a few years ago, but I
cannot find the reference right now. The delay (in the nanoseconds)
was because an impedance bump due to the bad connection acted as an
low pass filter, slowing the critical edge just enough. As I recall,
the offset was something like 60 ns.
On Wednesday, 8 July 2020 15:30:04 UTC+1, Joe Gwinn wrote:
On Tue, 7 Jul 2020 19:35:15 -0700 (PDT), RichD...
<r_delaney2001@yahoo.com> wrote:
Recall a few years back, a physics lab in Italy reported
faster than light neutrino observations. After some ado,
they finally diagnosed a dodgy optical interconnect.
It was explained to me by an engineer from CERN a few years ago, but I
cannot find the reference right now. The delay (in the nanoseconds)
was because an impedance bump due to the bad connection acted as an
low pass filter, slowing the critical edge just enough. As I recall,
the offset was something like 60 ns.
The implication being that the fibre is carrying discrete pulses to provide a time reference for the detected particles, rather than e.g. a network link.
Hence, changing the arrival time of the optical pulse alters the measured speed of the detected neutrinos.
Is that correct?
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