In: Statistics and Probability
Remind yourself about linear least squares fitting in section 3.2 of the lab manual, and then work through the following. In a particle physics experiment, there are six detectors at positions x = 10; 14; 18; 22; 26; and 30cm. These detectors measure the y positions of the trajectory of a charged particle to be 2.02; 2.26; 3.24; 3.33; 3.92; and 4.03 cm, respectively (i.e., the first position is (10,2.02), the second position is (14,2.26), and so on). The errors on the x positions are negligible; the first and last detectors have a y measurement error of ±0.10 cm, and the rest have a y measurement error of ±0.30 cm.
(a) Plot the points with their error bars.
(b) Perform a least squares straight-line fit to the data using the form y = a+bx. Find the values of a and b, and plot the resulting line along with the data points and their error
(c) Based on the χ 2 test, evaluate the quality of the fit.
SL NO | X | Y | XY | X2 |
1 | 10 | 2.02 | 20.2 | 100 |
2 | 14 | 2.26 | 31.64 | 196 |
3 | 18 | 3.24 | 58.32 | 324 |
4 | 22 | 3.33 | 73.26 | 484 |
5 | 26 | 3.92 | 101.92 | 676 |
6 | 30 | 4.03 | 120.9 | 900 |
Total | 120 | 18.8 | 406.24 | 2680 |