- #1
Lambda96
- 189
- 65
- Homework Statement
- Evaluation of an experiment
- Relevant Equations
- none
Hi,
I did a PET scan and positioned a sample almost in the center of a moving carriage, taking measurements along the x-axis and measuring the counts. Each measurement took 60 seconds, and I took a total of 27 measurements. Here are my results
As the display was in mm, I always assumed an error of 1 mm. For the error calculation of the counts, I used Poisson, i.e. ##\Delta count= \sqrt{n}## and for the errors of the counts per seconds I calculated as follows: ##\Delta## counts per second = ##\frac{\Delta count}{t}##
Now I have to do the following
Plot the position of the trolley (error discussion!) against the measured coincidence count rate graphically (with x-y errors). Fit the peak with a Gaussian curve (with x-y errors) and determine the FWHM. How does this result serve as an error for further measurements?
For the plots I used Origin and for the plot of the counts per second plus the error in x and y I had no problem and got the following:
Unfortunately, I'm not sure if I did the plot regarding the peak with the Gauss curve correctly and that I calculated the FWHM correctly, for FWHM I have used the formula ##FWHM=2 \sqrt{2 \ln{2}} \sigma##, where ##\sigma=1.4215## which means that ##FWHM=3.35##. But how do I calculate the error of the FWHM?
Here is the plot
I did a PET scan and positioned a sample almost in the center of a moving carriage, taking measurements along the x-axis and measuring the counts. Each measurement took 60 seconds, and I took a total of 27 measurements. Here are my results
As the display was in mm, I always assumed an error of 1 mm. For the error calculation of the counts, I used Poisson, i.e. ##\Delta count= \sqrt{n}## and for the errors of the counts per seconds I calculated as follows: ##\Delta## counts per second = ##\frac{\Delta count}{t}##
Now I have to do the following
Plot the position of the trolley (error discussion!) against the measured coincidence count rate graphically (with x-y errors). Fit the peak with a Gaussian curve (with x-y errors) and determine the FWHM. How does this result serve as an error for further measurements?
For the plots I used Origin and for the plot of the counts per second plus the error in x and y I had no problem and got the following:
Unfortunately, I'm not sure if I did the plot regarding the peak with the Gauss curve correctly and that I calculated the FWHM correctly, for FWHM I have used the formula ##FWHM=2 \sqrt{2 \ln{2}} \sigma##, where ##\sigma=1.4215## which means that ##FWHM=3.35##. But how do I calculate the error of the FWHM?
Here is the plot