Difference between revisions of "Sign of the beam polarization"

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Asymmetry at 90 degrees in the Center of Mass:
 
Asymmetry at 90 degrees in the Center of Mass:
 
<pre>
 
<pre>
−
[N(parallel) - N(anti-parallel)]/[N(parallel) + N(anti-parallel)]
+
[N(parallel) - N(anti-parallel)]/[N(parallel) + N(anti-parallel)] = -7/9
 
</pre>
 
</pre>
 +
 +
Moller solenoid field points DOWNSTREAM, so magnetic moments of electron in iron foil also point DOWNSTREAM.
 +
 +
Magnetic moment of electron given by:
 +
<pre>
 +
\vec{mu} = (g*e)/(2*m*c) \vec{s}
 +
</pre>
 +
 +
Electron has negative charge, so spin is in opposite direction of magnetic moment. Spin of polarized electrons in Moller target point UPSTREAM.
 +
 +
Experimental Moller asymmetry:
 +
<pre>
 +
A_DAQ = [h+ - h-]/[h+ - h-]
 +
</pre>
 +
 +
A_Moller<0, h+ denotes beam electrons polarized in the SAME direction as target spin: UPSTREAM
 +
 +
A_Moller>0, h+ denotes beam electrons polarized in the OPPOSITE direction as target spin: DOWNSTREAM
  
 
* Beni Zihlman's note on the sign of the helicity from the Moller: ([https://hallcweb.jlab.org/polwiki/images/0/0d/Helicity.ps ps], [https://hallcweb.jlab.org/polwiki/images/8/8f/Helicity.pdf pdf])
 
* Beni Zihlman's note on the sign of the helicity from the Moller: ([https://hallcweb.jlab.org/polwiki/images/0/0d/Helicity.ps ps], [https://hallcweb.jlab.org/polwiki/images/8/8f/Helicity.pdf pdf])

Latest revision as of 09:58, 1 December 2011

  • Notes on the sign of the beam polarization as determined by the Moller.

Asymmetry at 90 degrees in the Center of Mass: 

[N(parallel) - N(anti-parallel)]/[N(parallel) + N(anti-parallel)] = -7/9

Moller solenoid field points DOWNSTREAM, so magnetic moments of electron in iron foil also point DOWNSTREAM.

Magnetic moment of electron given by: 

\vec{mu} = (g*e)/(2*m*c) \vec{s}

Electron has negative charge, so spin is in opposite direction of magnetic moment. Spin of polarized electrons in Moller target point UPSTREAM.

Experimental Moller asymmetry: 

A_DAQ = [h+ - h-]/[h+ - h-]

A_Moller<0, h+ denotes beam electrons polarized in the SAME direction as target spin: UPSTREAM

A_Moller>0, h+ denotes beam electrons polarized in the OPPOSITE direction as target spin: DOWNSTREAM

  • Beni Zihlman's note on the sign of the helicity from the Moller: (ps, pdf)
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