垂直入射：

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E = 20; %20keV
Ek = 1000*E; 
v= Cal_V(Ek);
dx = 0.25;
lx = 140/dx+1;
dy = 0.25;
ly = 140/dy+1;
EM_record = zeros(Total,9);% 记录序号和初始位置速度、击中位置    
Total = lx*ly;
for k = 1:Total
    mx = dx*floor((k-1)/ly);
    my = dy*rem(k-1,ly);
    mz = 50;
    msita = 0; %垂直
    mphi = 0;%数值无关紧要
    P0 = [mx/1000,my/1000,mz/1000];
    V0 = [v*cos(-(msita/180+90/180)*pi)*sin((mphi/180)*pi), ...
        v*cos(-(msita/180+90/180)*pi)*cos((mphi/180)*pi), ...
        v*sin(-(msita/180+90/180)*pi)];
    EM_record(k,1:6) = [P0 V0];
end

170°入射

E = 20; %20keV
Ek = 1000*E; 
v= Cal_V(Ek);
dx = 0.25;
lx = 140/dx+1;
dy = 0.25;
ly = 140/dy+1;
EM_record = zeros(Total,9);% 记录序号和初始位置速度、击中位置    
Total = lx*ly;
for k = 1:Total
    mx = dx*floor((k-1)/ly);
    my = dy*rem(k-1,ly);
    mz = 50;
    msita = 10; %-170°
    mphi = 90; 
    P0 = [mx/1000,my/1000,mz/1000];
    V0 = [v*cos(-(msita/180+90/180)*pi)*sin((mphi/180)*pi), ...
        v*cos(-(msita/180+90/180)*pi)*cos((mphi/180)*pi), ...
        v*sin(-(msita/180+90/180)*pi)];
    EM_record(k,1:6) = [P0 V0];
end