PHYSICS · Multi-part · Fermi University Physics · Scientific Practice & Experimental Methods · Records, communication and the epistemology of evidence · Records, communication and the epistemology of evidence
Measurement and Method, Ch Writing the result, and the integrity of the data behind it
Problem
Three researchers, X, Y and Z, together with their supervisor, measure the half-life of a radioactive source with a Geiger-Müller counter over ten successive 30 s counting intervals, correcting each count for a measured background rate. Researcher X set up the apparatus and took all ten counts. Researcher Y wrote the background-subtraction and least-squares decay-fitting code and ran the fit. X and Y have both read the final draft and are willing to take responsibility for all of it. Researcher Z, before leaving the group, ran an independent Monte Carlo check that the fitting method itself was unbiased, using simulated counts rather than this dataset, and did not see the final draft of the report. The supervisor obtained the funding for the source and the counter and provided laboratory space, but did not look at the counts or the fit. Fitting all ten intervals gives t1/2=(138±9)s with χν2=6.7. The logbook records, timed during the run: "11:42, interval 7: counter output near zero for about 40 s; BNC cable to the tube found loose, reseated at 11:44." Excluding interval 7, the fit gives t1/2=(151±4)s with χν2=1.3. The submitted draft states only: "One anomalous interval was removed to improve the fit: t1/2=(151±4)s." It lists X and Y as authors, Z and the supervisor in the acknowledgements.
((a)) Apply the two conditions for authorship to X, Y, Z and the supervisor, and decide who should be listed as an author and who should be acknowledged; give acknowledgement wording for anyone not an author.
((b)) Judge whether the draft's sentence about interval 7 meets the disclosure standard, and rewrite it so that it does, using the numbers above.
((c)) A colleague who was not in the room asks, a year later, why interval 7 is missing from the decay curve. Name the records that answer this and state what each must show.