2.20 The strength of radioactive source is to be measured with a detector that has a background of 120 ± 8 counts/min. The approximate gross counting rate is 360 counts/min. How long should one count if the net counting rate is to be measured with an error of 2%?
Added by James A.
Close
Step 1
The net counting rate is the gross counting rate minus the background rate. In this case, it would be 360 counts/min - 120 counts/min = 240 counts/min. Show more…
Show all steps
Your feedback will help us improve your experience
Sri K and 100 other Intro Stats / AP Statistics educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
The activity of a radioactive sample was measured over $12 \mathrm{h}$ with the net count rates shown in the accompanying table. (a) Plot the logarithm of the counting rate as a function of time. (b) Determine the decay constant and half-life of the radioactive nuclei in the sample. (c) What counting rate would you expect for the sample at $t=0 ?$ (d) Assuming the efficiency of the counting instrument is $10.0 \%$, calculate the number of radioactive atoms in the sample at $t=0.$ $$\begin{array}{cc}\text { Time (h) } & \text { Counting Rate (counts/min) } \\\hline 1.00 & 3100 \\2.00 & 2450 \\4.00 & 1480 \\6.00 & 910 \\8.00 & 545 \\10.0 & 330 \\12.0 & 200 \\ \hline\end{array}$$
The following count rate data from a radioactive isotope were measured t (min) cnts/min t (min) cnts/min t (min) cnts/min 3.0 9302 24.0 3200 54.0 693 6.0 7932 30.0 2268 60.0 477 9.0 6901 36.0 1679 66.0 366 12.0 5853 42.0 1277 72.0 277 18.0 4397 48.0 962 78.0 165 From a plot of these data please estimate (a) the decay constant for the radioisotope, (b) the half-life, and (c) the count rate at t = 0.
Sri K.
The activity of a sample of radioactive material was measured over $12 \mathrm{h},$ and the following net count rates were obtained at the times indicated: $$\begin{array}{cc}\hline \text { Time (h) } & \text { Counting Rate (counts/min) } \\\hline 1 & 3100 \\2 & 2450 \\4 & 1480 \\6 & 910 \\8 & 545 \\10 & 330 \\12 & 200 \\\hline\end{array}$$ (a) Plot the activity curve on semilog paper. (b) Determine the disintegration constant and the half-life of the radioactive nuclei in the sample. (c) What counting rate would you expect for the sample at $t=0 ?$ (d) Assuming the efficiency of the counting instrument to be $10 \%,$ calculate the number of radioactive atoms in the sample at $t=0$
Recommended Textbooks
Elementary Statistics a Step by Step Approach
The Practice of Statistics for AP
Introductory Statistics
Transcript
Watch the video solution with this free unlock.
EMAIL
PASSWORD