Solar neutrino unit

Solar neutrino unit (SNU) is a new unit defined for convenience, which is more suitable for very low event rates.

In principle there are two ways of detecting solar neutrinos: radiochemical and real time experiments. The principle of radiochemical experiments is the reaction of the form

$^\{A\}\_\{N\}Z\; +\; u\_\{e\}longrightarrow^\{A\}\_\{N-1\}(Z+1)+e^\{-\}$.

The daughter nucleus's decay is used in the detection. Production rate of the daughter nucleus is given by

$R\; =\; NintPhi(E)sigma(E)dE$

where

* $Phi$ is the solar neutrino flux
* $sigma$ is the cross section for the radiochemical reaction
* $N$ is the number of target atoms.

With typical neutrino flux of $10^\{10\}\; [frac\{1\}\{cm^\{2\}s\}]$ and cross section of about $10^\{-45\}\; [\{cm^\{2]$ it is needed about $10^\{30\}$ (1 mole is equal to 6.022e|23) target atoms to produce one event per day. This number corresponds to ktons of the target substances, whereas present neutrino detectors operate at much lower quantities of those.

1 SNU is equal to $10^\{-36\}$ captures per target atom per second.

See also

*Neutrino
*Neutrino detector
*Mole (unit)