(1) According to the conservation of mass number and proton number,

Then the attenuation equation is:? 137N→? 136C+？ 0 1e

(2) According to the left-handed rule and the relationship between force and motion, the trajectory diagram is shown in the figure.

(3) According to the law of conservation of momentum, mcvc=meve is obtained.

Is the orbital radius of recoil nucleus or carbon nucleus R2?

R2=mcvc6eB

Positron r = meveeb

So what? r=3R

As can be seen from the figure, the coordinates x and y of the position p where positrons are emitted from the magnetic field satisfy:

According to the geometric relationship, r2=x2+(r-y)2?

R2=x2+y2

The result of the solution is x = 356 r.

y=R6

A: (1) The decay equation is:? 137N→? 136C+？ 0 1e；

(2) Draw the trajectory diagram of positron and recoil nucleus as shown on the right;

(3) The coordinates (356R, R6) of the positron leaving the magnetic field.