Distance Dependence of Radiation

1.1 Prelab 1: (+5)

To get

,

where

,

and for Poisson statistics,

.

Combining the above equations, we get,

,

thus

.

1.2 Prelab 2: (+5)

For a measurement of 10 minutes for both the observation and background data,

.

Then the rate is,

.

CAUTION: Using count/s will lose the precision of the data.

1.3 Prelab 3: (+5)

Plot ln x on the horizontal axis, and ln y on the vertical axis, then the intercept is ln a and the slope is b.

2. Data: (+5)

a. For the background data, the average and standard deviation should not have decimal places. No quantity is physical without uncertainty.

b. Please state clearly that the measurement is taken within an interval of 30 seconds.

c. Don't forget to report the error of ruler.

d. For corrected data, due to (a) in this step, there should not be decimal places as well.

3. Uncertainty: (+5)

The distance from the disk and the receiver cannot be measured, since we don't know the exact position of the receiver.

4. Plots: (+5)

Don't forget to plot the uncertainties, in a correct way --- choose the uncertainty, not using the default value set by Excel.

5. Results: (+5)

The sig figs & decimal places should be determined correctly. Simply speaking, for plus or minus operations, the number of decimal places goes with the least one; for other mathematical operations, the sig figs goes with the least.

6. Discussion: (+10)

Improve the precision:

Since the distance from the source to the receiver cannot be well determined (We were measuring the distance from the disk to the equipment, but the exact distance, L, from the surface of the equipment to the receiver is unknown), we can measure the radiation in further places, decreasing the fractional contribution of L in the total distance d therefore.

7. Style: (+5)

Positions of table/figure legends;

Correct submission titles.