On Earth, the number flux of solar neutrinos from the p-p chain is:

f_neutrino = 2fo/2.62MeV

Other nuclear reactions in the Sun supplement this neutrino flux with a small additional flux of higher-energy neutrinos. A neutrino detector in Japan, named SuperKamiokande, consists of a tank of 50 kton of water, surrounded by photomultiplier tubes. The tubes detect the flash of Cerenkov radiation emitted by a recoiling electron when a high-energy neutrino scatters on it.

Required:
a. How many electrons are there in the water of the detector?
b. Calculate the detection rate for neutrino scattering, in events per day.

Respuesta :

Answer:

Explanation:

The volume of the tank = 50 kton

50 kton = 5 × 10⁷ kg

Since 18 grams of water will contain: 10 electrons × 6.023 × 10²³

Then;

5× 10⁷ kg will contain [tex]( \dfrac{5 \times 10^7 \times 10^3}{18}) \times 10 \times 6.023 \times 10^{23}[/tex]

= 1.67 × 10³⁴ electrons

(b)

Suppose:

[tex]f_{neutrino} = \dfrac{2f_o}{26.2 MeV} = 6.7\times 10^{10} \ s^{-1} cm^{-2}[/tex]

Then;

10⁻⁶ of [tex]f_{neutrino} = 6.7 \times 10^{10} \times 10^{-6} \ s^{-1} cm^{-2}[/tex]

[tex]=6.7 \times 10^{4}\ s^{-1} cm^{-2}[/tex]

Thus, the number of high energy neutrinos which will interact with water is:

= [tex]6.7 \times 10^4 \times \sigma[/tex]

= [tex]6.7 \times 10^4 \times 10^{-43}[/tex]

= [tex]6.7 \times 10^{-39} s^{-1}[/tex]

For  1.67 × 10³⁴ electrons, the detection rate is:

[tex]6.7 \times 10^{-39} \times 1.67 \times 10^{34}[/tex]

[tex]= 11.19 \times 10^{-5} \ s^{-1}[/tex]

= 9.668 per day