Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Geoff McGuire on 01/12/2011 23:30:03

Title: How are neutrinos detected?
Post by: Geoff McGuire on 01/12/2011 23:30:03

Geoff McGuire  asked the Naked Scientists:
   
Hi Chris,

What is the latest technique used for detecting neutrinos in real time?

Regards

Geoff McGuire - MicroSpy Limited.

What do you think?

Title: How are neutrinos detected?
Post by: yor_on on 03/12/2011 00:36:12

"The OPERA experiment has been designed to perform the most straightforward test of the phenomenon of neutrino oscillations. This experiment exploits the CNGS high-intensity and high-energy beam of muon neutrinos produced at the CERN SPS in Geneva pointing towards the LNGS underground laboratory at Gran Sasso, 730 km away in central Italy. OPERA is located in the Hall C of LNGS and it is aimed at detecting for the first time the appearance of tau-neutrinos from the transmutation (oscillation) of muon-neutrinos during their 3 millisecond travel from Geneva to Gran Sasso.

In OPERA, tau-leptons resulting from the interaction of tau-neutrinos will be observed in "bricks" of photographic emulsion films interleaved with lead plates. The apparatus contains about 150000 of such bricks for a total mass of 1300 tons and is complemented by electronic detectors (trackers and spectrometers) and ancillary infrastructure. Its construction has been completed in spring 2008 and the experiment is currently in data taking."

Title: How are neutrinos detected?
Post by: yor_on on 03/12/2011 03:23:04

"What they claim to have found, though, is neutrinos arriving 60 nano-seconds (0.00000006 seconds) early. If accurate, this would be a six standard-deviation result – enough to convince physicists that something is genuinely awry.

There’s the issue of knowing the exact positions of the source and detector to within the quoted uncertainty – keeping in mind that in the extra 60 nano-seconds the neutrinos are supposedly travelling they will cover a total of 18 metres. This means knowing those two positions – and the geodesic distance between them – to within three metres out of 730,000 metres."

Title: How are neutrinos detected?
Post by: imatfaal on 03/12/2011 08:46:38

Yoron - could you post where those quotes are from so that forum members could read in more details and/or evaluate sources ?

Title: How are neutrinos detected?
Post by: Soul Surfer on 03/12/2011 10:03:56

Here is a link to the original paper it contains quite readable descriptions of the kit

http://static.arxiv.org/pdf/1109.4897.pdf

Title: How are neutrinos detected?
Post by: CliffordK on 03/12/2011 13:05:36

Quote from: yor_on on 03/12/2011 03:23:04

keeping in mind that in the extra 60 nano-seconds the neutrinos are supposedly travelling they will cover a total of 18 metres. This means knowing those two positions – and the geodesic distance between them – to within three metres out of 730,000 metres."

3 Meters?

I thought GPS accuracy was less than a foot, at least for X & Y measurements.  Z may still be a bit problematic.  Precision of GPS readings should be improved if two locations take simultaneous readings using several of the same satellites.

Anyway, one would certainly want to re-survey things with the latest space equipment.  NATO?  But, it should be possible to get a survey with XYZ accuracy to less than a meter, perhaps even a few cm.  Or... I should say precision, as the absolute location is much less important than the relative locations of the emitter and detector.

Is all the equipment aimed in the right direction?

Title: How are neutrinos detected?
Post by: yor_on on 03/12/2011 15:23:12

They are as good as what you are prepared to pay for nowadays, at least the American system as far as I understand. But there is also this to consider: User Equivalent Range Errors (https://www.e-education.psu.edu/natureofgeoinfo/c5_p20.html) And the more accurate you want to be, the more difficult it will be. I'm guessing they are using Carrier Phase Tracking (http://www.colorado.edu/geography/gcraft/notes/gps/gps.html) to define their positions relative each other.

Title: How are neutrinos detected?
Post by: yor_on on 03/12/2011 15:32:39

This one might be interesting too.

Regular GPS not accurate enough? Try RTK-GPS! (http://blog.makezine.com/archive/2009/11/diy-real-time-kinematic-gps.html) But read the comment section too, to get a better idea of the limitations.

Title: How are neutrinos detected?
Post by: imatfaal on 03/12/2011 17:41:56

If the Guys and Girls at Gran Sasso have done there sums correctly (and followed their instructions properly [B)] ) then the error in the time synchronization (discussed in other thread) is about 2 nanoseconds and the distance error is about 20cm

Title: How are neutrinos detected?
Post by: CliffordK on 03/12/2011 19:41:44

Trimble claims 10cm, or 4" accuracy in their equipment:
http://www.trimble.com/pathfinderproxh.shtml

Wikipedia also has a discussion about GPS accuracy, and augmentation of the accuracy.
http://en.wikipedia.org/wiki/GPS_augmentation

Accuracy of GPS can be enhanced by the use of a ground located base station.  However, one still needs to know the precise location of the base station. 

I would imagine readings could also be averaged over time (and, of course, time-synchronized between the two distant locations).

Anyway, the accuracy needed for these measurements is pretty extraordinary.

Title: How are neutrinos detected?
Post by: yor_on on 04/12/2011 10:58:29

It's right at the 'bleedin edge' practically seen.

I will wait before I decide if they are right.