- #1
lalbatros
- 1,256
- 2
Hello,
I just spent some time reading the recent OPERA-CNGS paper on apparently FTL neutrinos (http://arxiv.org/abs/1109.4897) .
In this reading, I have some difficulty to clearly see how the arrivals events are processed.
I am not even sure I understood properly basic information like:
- what the "chronometer" start event is
- how many pulses of 10µs where included in the analysis
- how many neutrinos where detected (is that the 16111 event mentioned?)
- how the 200 MHz source intensity oscillations are used/needed in the data processing
- if the rise time of the 10µs proton waveform plays any role in the analysis
- what is meant by "extraction"
- ...
I would like to understand more clearly how the data analysis proceeds without keeping the useless technical details. I would like to select the usefull information from this paper, as far as data processing is involved.
My current understanding is that when a 10µs proton pulse is produced, most often no neutrino is detected in Gran Sasso. During this 10µs proton pulse, the proton intensity oscillates about 2000 times between high and low intensity (5ns period). Therefore, a neutrino occasionally detected in Gran Sasso has more probability to have been produced during one of the 2000 high-intensity phases that during any of the 2000 low-intensity phases.
However, I do not see why any of the 2000 high intensity period would have a higher probability, and therefore I also do not understand why the time of flight could be determined with a precision better that 10µs, while the effect being discussed deals with a precision of about 10ns!
I really must have missunderstood something.
How was it possible to measure the time of flight with a 10ns precision, based on theis 10 µs proton pulse?
Thanks for your help.
Michel
I just spent some time reading the recent OPERA-CNGS paper on apparently FTL neutrinos (http://arxiv.org/abs/1109.4897) .
In this reading, I have some difficulty to clearly see how the arrivals events are processed.
I am not even sure I understood properly basic information like:
- what the "chronometer" start event is
- how many pulses of 10µs where included in the analysis
- how many neutrinos where detected (is that the 16111 event mentioned?)
- how the 200 MHz source intensity oscillations are used/needed in the data processing
- if the rise time of the 10µs proton waveform plays any role in the analysis
- what is meant by "extraction"
- ...
I would like to understand more clearly how the data analysis proceeds without keeping the useless technical details. I would like to select the usefull information from this paper, as far as data processing is involved.
My current understanding is that when a 10µs proton pulse is produced, most often no neutrino is detected in Gran Sasso. During this 10µs proton pulse, the proton intensity oscillates about 2000 times between high and low intensity (5ns period). Therefore, a neutrino occasionally detected in Gran Sasso has more probability to have been produced during one of the 2000 high-intensity phases that during any of the 2000 low-intensity phases.
However, I do not see why any of the 2000 high intensity period would have a higher probability, and therefore I also do not understand why the time of flight could be determined with a precision better that 10µs, while the effect being discussed deals with a precision of about 10ns!
I really must have missunderstood something.
How was it possible to measure the time of flight with a 10ns precision, based on theis 10 µs proton pulse?
Thanks for your help.
Michel