Electron Spin Question
Bruce Harvey
Regards Bruce
--
Bruce Harvey, br...@bearsoft.powernet.co.uk
My web-site is "The Alternative Physics Site"
http://users.powernet.co.uk/bearsoft/
jhec...@my-dejanews.com
Bruce Harvey <br...@bearsoft.powernet.co.uk> wrote:
>
> What evidence is there for the magnetic momnet of free electrons?
>
> Regards Bruce
>
Um, do you mean besides the Stern-Gerlach experiment, which is described in
every introductory and intermediate book on Quantum Mechanics that's ever been
written?
Technically, I seem to recall that Stern and Gerlach did their original
experiment with Silver ions or some such, but I'd be astonished if it hasn't
since been done with free electrons.
Jim Heckman
..
"As I understand it, your actions have ensured
that you will never see Daniel again."
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
Kevin A. Scaldeferri
<jhec...@my-dejanews.com> wrote:
>In article <ant181336d07ZDq#@bearsoft.powernet.co.uk>,
> Bruce Harvey <br...@bearsoft.powernet.co.uk> wrote:
>>
>> What evidence is there for the magnetic momnet of free electrons?
>
>every introductory and intermediate book on Quantum Mechanics that's ever been
>written?
>
>Technically, I seem to recall that Stern and Gerlach did their original
>experiment with Silver ions or some such, but I'd be astonished if it hasn't
>since been done with free electrons.
Probably he does mean besides the Stern-Gerlach experiment which was
done with silver atoms, not silver ions or electrons since the charge
coupling to the E-field would swamp the magnetic moment coupling to
the inhomogeneities in the E-field.
To the original poster, the magnetic moment of free electrons is one
of the most well measured quantities in physics. I think the standard
way of doing this is to trap it using electric and magnetic fields and
tuning to a spin resonance. Some of the experimental types around
here can probably give more details.
--
======================================================================
Kevin Scaldeferri Calif. Institute of Technology
The INTJ's Prayer:
Lord keep me open to others' ideas, WRONG though they may be.
jhec...@my-dejanews.com
ke...@cco.caltech.edu (Kevin A. Scaldeferri) wrote:
>
> Probably he does mean besides the Stern-Gerlach experiment which was
> done with silver atoms, not silver ions or electrons since the charge
> coupling to the E-field would swamp the magnetic moment coupling to
> the inhomogeneities in the E-field.
>
> measured in practice.]
>
> --
> ======================================================================
> Kevin Scaldeferri Calif. Institute of Technology
>
Yeah, I thought of that later when I looked it up myself. Although charge
coupling would certainly dominate with free electrons, I wonder whether it
still wouldn't be possible to do a version of Stern-Gerlach with them. It
seems like it should -- all you really need to show a magnetic moment and its
rough magnitude is that the beam separates into 2 parts. I guess you'd have
to have a *very* tightly calibrated incoming beam in terms of momentum and
angular dispersion, though, to get a clear magnetic moment signal among the
spreading from the charge coupling. Has such an experiment been done?
Bruce Harvey
<URL:mailto:jhec...@my-dejanews.com> wrote:
I am tagging this to the last entry to keep the thread intact, but
answering the previous 3 postings.
Many thanks for answering, Jim and Kevin
>Um, do you mean besides the Stern-Gerlach experiment
Yes that is why I said free electrons. The use of silver atoms in SG
means that you are just measuring the orbital magnetic moment of the odd
unpaired electron.
>To the original poster, the magnetic moment of free electrons is one
>of the most well measured quantities in physics. I think the standard
>way of doing this is to trap it using electric and magnetic fields and
>tuning to a spin resonance. Some of the experimental types around
>here can probably give more details.
Any information about this method would be appreciated as I have no
reference to it any of my modern physics books. They just give details
of the SG experiment.
> Yeah, I thought of that later when I looked it up myself. Although charge
> coupling would certainly dominate with free electrons, I wonder whether it
> still wouldn't be possible to do a version of Stern-Gerlach with them. It
Since this is such a fundermental assertion of modern physics, I am
supprised that none of the laboratory demonstration equipment firms have
produced a commertial piece of apparatus as a teaching aid.
The trick would be to use small numbers of low velocity electrons in a
CRT with curved SG type magnets following the path of the electrons and
the amplifier bits and pieces from a photon multiplier.
In the absence of such a demonstration of the existence of the magnetic
moment in free electrons, perhaps we might question the concept.
I have two main problems with it.
The first is that I can not understand how so
large a magnetic momnet it is generated by so small a charge. Clasical
physics requires the electron charge to move around a current loop the
size atributed to the electron at 137 times the speed of light. 137 bing
1/ fine structure constant.
The second is that small objects with magnetic moment exert a torque on
each other proportional to 1/r^3 and an atractive force proportional to
1/r^4. At close range this atractive force becomes stronger that the
coulomb force. My iteration of motion under an inverse forth power force
shows no equivalent of the parabolic or eliptic paths of motion under an
inverse square law. Depending on velocity and path, either they have
little effect on each others motion, or they rapidly spiral to collide.
Any comments on these speculations would be apreciated.
AgeofSelf
I enjoin and challenge all with great spiritual and intellectual gifts an
opportunity learn even more about yourselves and others in search of
Self-Awareness and Discovery. Altho many have checked out the site, few have
joined in starting forums and open chats. Eventually I will become more
detailed in my project but I wish to get a good group of interested persons to
form a basis to work with. I know this takes time, I will struggle to keep
things together, and I am looking for researchers to start with.
OPEN CHAT SUNDAY
www.geocities.com/area51/keep/7222
Good Luck To All In Your Endeavors.