In an experiment involving radioactive decay the number of decays detected (counted) during a one minute period is recorded at various times after the production of the radioactive material (x in minutes). This count, called the activity N, is displayed below as the y-variable. The measurement uncertainty in the activity, given by Poisson statistics, follows the square root rule:

δN = sqrt(N)

According to Ernest Rutherford, the activity should follow and exponential relationship:

N = N0 exp(-λt)

where N0 is the initial activity and λ is called the decay constant. The decay constant is inversely related to the half-life of the material:

T1/2 = .693/λ

  1. Fit this data to an exponential relationship.
  2. Consider Rutherford's scientific claim of an exponential law. Does this evidence (data) confirm or contradict this claim? Support your answer quantitatively.
  3. Properly report (sigfigs, error, units) the A and B parameters of the best-fit function.
  4. Use a spreadsheet to calculate the half-life from B, and properly report (sigfigs, error, units) the value.
  5. Self-document the spreadsheet and turn in a hardcopy of the page.
  6. Make a hardcopy plot of the data with best-fit curve. Make an additional hardcopy plot with scales chosen so as to linearize the curve.

X
(min)
Y
(counts)
91.566 × 103
121.380 × 103
171.053 × 103
31 462
43 284
55 135
59 115
62 72
76 51
80 43