Note on Solar Neutrino Experiments

			Takeshi K. Komatsubara (KEK-IPNS)
			2003-June-12(Thu)

 There are three processes for detecting ^8B solar neutrinos (5<E<14MeV).
 The SNO experiment (with heavy water) can detect all of these,
 while Kamiokande/SuperKamiokande (with water) detects one of them. 


 1. Charged Current (CC) reaction of neutrino and deuteron [SNO]:

	    nu_el + D --> p + p + e^- 

    This is EXCLUSIVELY from the nu_e flux.
    The electron would be scattered to the backward 
    of the original nu_e direction.


 2. Elastic Scattering (ES) of neutrino and electron [both SNO and SK]: 

	    nu_x + e^- --> nu_x + e^-   x=el,mu,tau 

    The cross sections of mu and tau neutrinos (Neutral Current with Z)
    are smaller (15% for each) than 
    the cross section of el neutrino 
    (Charged Current with W and Neutrino Current with Z).
    This is MOSTLY from nu_el flux.
    The electron would be scattered to the forward 
    of the original nu_e direction.


 3. Neutral Current (NC) reaction of neutrino and deuteron [SNO]
    
	    nu_a + D --> nu_a + p + n   a=el,mu,tau

    The cross sections of el, mu and tau neutrinos are almost equal.
    This is the TOTAL neutrino flux from the sun. 
    The neutron interacts with a deuteron and a monochromatic gamma ray
    (6 MeV) would be emitted isotropically. 



 The pages 26-28 of hep-ph/0204288 should be read like this
 ( '**   **' : my corrections).

  "The Kamiokande and Super-Kamiokande experiments are water Cherenkov
  detector. Here ** the elastic scattering (RS) in fig.12 **, 
	    nu_x + e^- --> nu_x + e^-   (107)
  is used to detect solar neutrinos. ...
   An important step towards the final resolution of the solar neutrino
  problem was made by the recent results of the Sudbury Neutrino Observatory
  (SNO). Like the SuperKamiokande, high-energy ^8B neutrinos are observed, 
  this time in a 1000 t detector of heavy water D_2O. This allows the 
  observation of the charged current (CC) reaction
	    nu_el + D --> p + p + e^-   (108)
  as well as the ** neutral current (NC) reaction  
	    nu_a + D --> nu_a + p + n   (109). **
  From the CC reaction (108) ...
   Alternatively, one may assume that electron-neutrinos have partially 
  been converted into muon- and tau-neutrinos. In this case, the flux
  extractedfrom the ** NC reaction ** (109) should coincide with the flux
  of ^8B neutrinos. One finds ..."


---- End of this note.