Procedure+for+Energy+Efficiency+calibration

Back to Main =Efficiency Calibration Curve=

Make an efficiency calibration curve, where the counting efficiency is given as a function of γ energy. In table 1 the measured nuclei is listed with γ energy, number of counts, uncertainty in the number of counts and the counting time. The measurements was performed 27th March 2003.
 * ~ table 1 : measurement data from standard γ -calibartion sources, measured 6. oct 2006. ||
 * Nuclide || Energy (keV) || Counts || Uncertainty || Real Time (s) ||
 * 137 Cs || 661.66 || 161681 || 432 || 210 ||
 * 133 Ba || 80.997 || 99426 || 408 || 380 ||
 * || 276.398 || 13284 || 150 || 380 ||
 * || 302.853 || 31734 || 202 || 380 ||
 * || 356.017 || 92291 || 322 || 380 ||
 * 241 Am || 59.54 || 407142 || 766 || 376 ||
 * 60 Co || 1173.237 || 14039 || 137 || 189 ||
 * || 1332.501 || 12822 || 121 || 189 ||
 * 54 Mn || 834.84 || 317 || 26 || 1268.56 ||
 * 152 Eu || 121.78 || 486526 || 1031 || 1111 ||
 * || 244.698 || 82174 || 519 || 1111 ||
 * || 344.279 || 211766 || 625 || 1111 ||
 * || 778.9 || 48601 || 396 || 1111 ||
 * || 295.939 || 4076 || 245 || 1111 ||
 * || 964.079 || 45298 || 359 || 1111 ||
 * || 1408.006 || 47191 || 237 || 1111 ||
 * || 344.279 || 211766 || 625 || 1111 ||
 * || 778.9 || 48601 || 396 || 1111 ||
 * || 295.939 || 4076 || 245 || 1111 ||
 * || 964.079 || 45298 || 359 || 1111 ||
 * || 1408.006 || 47191 || 237 || 1111 ||

A table of the γ intensities, I γ, can be found [|Gamma-Energy Standards] To calculate the efficiency you need to know the amount of activity in the sources. Table 2 lists the amount of activity at the time of purchase. You must correct these number based upon the age and half life of the sources.


 * ~ table 2: activety of standards ||
 * Nuclide: || activety: || Date ||
 * 60 Co || 10.57 μ Ci || 1. oct 1988 ||
 * 133 Ba || 6.09 μ Ci || 1. oct 1988 ||
 * 54 Mn || 367 kBq || 1. apr 1996 ||
 * 137 Cs || 11.5 μ Ci || 1. oct 1988 ||
 * 241 An || 11.56 μ Ci || 1. oct 1988 ||
 * 152 Eu || 3.71 μ Ci || 1.apr 2004 ||

=Determination of Unknown Sample=

In table 3 the analysis results of the unknown, n-irradiated sample is shown. Use the results to :
 * Determine which metal the sample consist of. Use the identified γ -ray energies to do this. if you need a database you can use [|this one]
 * Determine the absolute amount of the metal. Use the counts measured in table 3 and the efficiency curve you made in exercise 3B. Use at least two different γ lines to do this, we recommend E γ = 222.08 keV and E γ 1 MeV. The neutron flux was 10 5 n/(s cm 2 ) during the irradiation, and the irradiation time was 18 days. The sample was measured directly after the irradiation.


 * ~ Table 3: Results from spectroscopy of unknown sample ||
 * Photo Peak no. || Energy (keV || Net Count || Uncertainty || FWHM (keV ||
 * 1 || 67.63 || 166011 || 1885 || 0.44 ||
 * 2 || 100.26 || 79985 || 902 || 1.00 ||
 * 3 || 152.56 || 34987 || 401 || 1.16 ||
 * 4 || 222.08 || 29011 || 335 || 1.52 ||
 * 5 || 511 || 210890 || 2385 || 2.24 ||
 * 6 || 1121.14 || 32098 || 391 || 1.67 ||
 * 7 || 1188.7 || 14563 || 173 || 1.17 ||
 * 8 || 1221.28 || 23825 || 265 || 2.01 ||