% File: http://web.mit.edu/8.13/matlab/Examples/alphas.m
% Author: Scott Sewell
% Date: 2008-June-11

% Example linear fit to Geiger-Nuttall Data from French and Taylor ``An
% Introduction to Quantum Mechanics'', 1978,  Table 9-1, Page 407.
% Requires 'fitlin.m'

figure;
ftx=[0.497 0.452 0.425 0.423 0.404 0.381 0.358 0.335]; % 1/sqrt(E)
fty=[-17.8 -10.9 -7.9 -5.7 -2.4 0.6 3.6 6.4];  % log10(gamma) [per sec]
ftsig=.1*fty;
errorbar(ftx,fty,ftsig,'.');
axis([.3 .55 -20 10]);
ylabel('log_{10} \gamma','fontsize',14);
xlabel('E^{-1/2}','fontsize',14);
title({'Test of the theoretical relationship between','decay constant and emitted \alpha particle energies'},'fontsize',16');
legend('French and Taylor (1978)');
[fta,ftaerr,ftchisq,ftyfit] = fitlin(ftx,fty,ftsig);
hold on;
plot(ftx,ftyfit,'R-');
Parameters = [fta', ftaerr']
rchisq=ftchisq/(length(ftx)-1);
text(.33,-12.5,'Barrier Penetrability \sim Ae^{-C/E^{1/2}}');
text(.33,-15,'log10\gamma = const - 155/E_{MeV}^{1/2}');
text(.33,-10,'Fit Slope = -145 \pm 5');
text(.34,8,'Th^{232}');
text(.5,-16,'Po^{212}');