The Naked Scientists

The Naked Scientists Forum

Author Topic: How were neutrinos discovered?  (Read 11110 times)

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
How were neutrinos discovered?
« Reply #25 on: 06/10/2011 10:36:31 »
Hi Imatfaal,
Thanks for the link. Also to Damocles.
 Which neutrino "flavours" are in action at CERN.
Johann

Didn't notice this bit.  CERN/OPERA Gran Sasso was set up to look at the oscillations of neutrinos that we were talking about above.  CERN was able to use a proton beam striking a graphite wall to produce a beam of mesons that with a little filtering and magnetic channelling would end up decaying and producing a beam of almost solely mu-neutrinos.  This beam of νμ was directed at Gran Sasso ~730km away.  Gran Sasso was set up to detect ντ however - and it was hoped that accurate measurements of the change and probabilities of oscillation could be made.  I haven't read up on the Gran Sasso detectors (lotsa lead and photo-multipliers) so I cannot say if they were only detecting ντ - but I presume they must have been able to either measure only ντ or differentiate ντ from νμ and νe for their experiment to work
 

Johann Mahne

  • Guest
How were neutrinos discovered?
« Reply #26 on: 26/10/2011 22:28:21 »
Quote
I hate to agree with everybody above but SSurfers comments on spin are spot on.  This is a cut-off point where you can no longer think classically - the electron cannot be seen as a little globe spinning on its axis; if it was the surface would be travelling at a velocity above c.  Spin is an intrinsic property - which is testable,predictable, and closely connect to angular momentum ; but it is not a little particle spinning like a top
Stephen Hawkins says that if a particle has for example a spin of 0 then it always "looks the same" from all directions
If it has a spin of 2, it "looks the same" for every 180 degrees of rotation.
  Is he talking about the electrostatic or magnetic fields that "look the same", or something else?
How is this spin related to angular momentum?
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
How were neutrinos discovered?
« Reply #27 on: 27/10/2011 12:13:05 »
Quote
I hate to agree with everybody above but SSurfers comments on spin are spot on.  This is a cut-off point where you can no longer think classically - the electron cannot be seen as a little globe spinning on its axis; if it was the surface would be travelling at a velocity above c.  Spin is an intrinsic property - which is testable,predictable, and closely connect to angular momentum ; but it is not a little particle spinning like a top
Stephen Hawkins says that if a particle has for example a spin of 0 then it always "looks the same" from all directions
If it has a spin of 2, it "looks the same" for every 180 degrees of rotation.
  Is he talking about the electrostatic or magnetic fields that "look the same", or something else?
How is this spin related to angular momentum?

Stephen Hawking is a great scientist and mathematician - and I wouldn't and couldn't criticise his work; but his popularizations can be a bit odd.  He will quite happily give a great and accessible explanation for a incredibly difficult concept (which I will lap up and feel I understand) and then a few paragraphs later say that the explanation was of""heuristic value only" ie not really true. 

I do not know if this is one of those occasions but I suspect it is.  Spin is an intrinsic and basic property of fundamental particles - and like the other ones it is very hard to get to the nitty-gritty of what it actually is!

A good start is Wikipedia's page Spin(physics)
« Last Edit: 28/10/2011 11:01:28 by imatfaal »
 

Offline acsinuk

  • Sr. Member
  • ****
  • Posts: 236
  • Thanked: 1 times
    • View Profile
    • electricmagnofluxuniverse.blogspot.com
How were neutrinos discovered?
« Reply #28 on: 27/10/2011 17:27:46 »
Spin and current loops are interlinked magnetically.  But how can 3D current loop spin or frequency be linked into the standard model? CliveS
 

Offline GlentoranMark

  • Full Member
  • ***
  • Posts: 98
    • View Profile
How were neutrinos discovered?
« Reply #29 on: 27/10/2011 23:19:07 »
I listened to this Podcast yesterday, perhaps it may be of use to the OP and others.

http://www.bbc.co.uk/programmes/b0106tjc

Melvyn Bragg and his guests discuss the neutrino.

In 1930 the physicist Wolfgang Pauli proposed the existence of an as-yet undiscovered subatomic particle. He also bet his colleagues a case of champagne that it would never be detected. He lost his bet when in 1956 the particle, now known as the neutrino, was first observed in an American nuclear reactor.

Neutrinos are some of the most mysterious particles in the Universe. The Sun produces trillions of them every second, and they constantly bombard the Earth and everything on it. Neutrinos can pass through solid rock, and even stars, at almost the speed of light without being impeded, and are almost impossible to detect. Today, experiments involving neutrinos are providing insights into the nature of matter, the contents of the Universe and the processes deep inside stars.

With:

Frank Close
Professor of Physics at Exeter College at the University of Oxford

Susan Cartwright
Senior Lecturer in Particle Physics and Astrophysics at the University of Sheffield

David Wark
Professor of Particle Physics at Imperial College, London, and the Rutherford Appleton Laboratory.

Producer: Thomas Morris.
 

Johann Mahne

  • Guest
How were neutrinos discovered?
« Reply #30 on: 28/10/2011 04:12:39 »
Thanks for all the excellent links.
This is the re formatted link of Imatfaal
http://en.wikipedia.org/wiki/Spin_%28physics%29
« Last Edit: 28/10/2011 05:57:56 by Johann Mahne »
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
How were neutrinos discovered?
« Reply #31 on: 28/10/2011 11:01:10 »
Thanks Johann - I had a curly instead of a square bracket

Have modified the original
 

The Naked Scientists Forum

How were neutrinos discovered?
« Reply #31 on: 28/10/2011 11:01:10 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums