Test of a small Geiger counter and the gamma FTLAB module.

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             The gamma FTLAB is a low sensitivity detector. The table below summarizes some of the results got with that detector during one hour time so the comparison with the scintillators can be immediately done.  To reach the same statistics, the measurement time should be greatly increased.

 
Sample Weight g Detector Discriminator Voltage Counting Time (secondes) Background Total counts Net counts Critical limit Lc Minimum detectable activity Minimum detectable activity Bq Detected activity Bq Ratio Net_counts / Min Detect activity
Burangaite 117 FTLAB  internal 3600 22 49 27 10.91 24.5 0.0068 0.0075 1.10
Burangaite 117 FTLAB 0.1 3600 47 100 53 15.95 34.6 0.0096 0.0147 1.53
Burangaite 117 FTLAB 0.3 3600 31 56 25 12.95 28.6 0.0079 0.0069 0.87
Lutetium 5 FTLAB  internal 3600 25 46 21 11.63 26.0 0.0072 0.0058 0.81
Lutetium 5 FTLAB 0.1 3600 99 169 70 23.15 49.0 0.0136 0.0194 1.43
Lutetium 5 FTLAB 0.3 3600 33 59 26 13.36 29.4 0.0082 0.0072 0.88
Monazite 14 FTLAB  internal 3600 25 11274 11249 11.63 26.0 0.0072 3.1247 433.16
Monazite 14 FTLAB 0.1 3600 99 24228 24129 23.15 49.0 0.0136 6.7025 492.42
Monazite 14 FTLAB 0.3 3600 33 13765 13732 13.36 29.4 0.0082 3.8144 466.53
Pechblende 58.5 FTLAB 0.1 3600 99 355805 355706 23.15 49.0 0.0136 98.8072 7259.24
Pechblende 58.5 FTLAB 0.3 3600 33 237067 237034 13.36 29.4 0.0082 65.8428 8053.04
Thorium Nitrate 14.7 FTLAB  internal 3600 25 27876 27851 11.63 26.0 0.0072 7.7364 1072.44
Thorium Nitrate 14.7 FTLAB 0.15 3600 99 49759 49660 23.15 49.0 0.0136 13.7944 1013.46
Thorium Nitrate 14.7 FTLAB 0.3 3600 33 35875 35842 13.36 29.4 0.0082 9.9561 1217.70
U3O8 15.5 FTLAB  internal 3600 25 61783 61758 11.63 26.0 0.0072 17.1550 2378.07
U3O8 15.5 FTLAB 0.1 3600 99 124543 124444 23.15 49.0 0.0136 34.5678 2539.65
U3O8 15.5 FTLAB 0.3 3600 33 85377 85344 13.36 29.4 0.0082 23.7067 2899.49

 
   

          Table below summarizes the results with the gamma FTLAB with an integration time of 12 hours. It is possible with this increased counting time to detect the radioactivity of some samples but the very low activity is barely detected with the FTLAB module. The detection power of the NaI scintillator in one hour counting time is better then the FTLAB with 12 hours measurement time. The integration time of the FTLAB could be further increased to improve the detection power but this is impractical.

 
Sample Detector Discriminator Voltage Counting Time (hours) Background Total counts Net counts Critical limit Lc Minimum detectable activity Minimum detectable activity Bq Detected activity Bq Ratio Net_counts / Min Detect activity
Apatite blue India FTLAB Internal 12 333 2318 1985 42.45 87.6 7.3009 165.4167 22.66
Apatite blue India FTLAB 0.25 12 672 4619 3947 60.31 123.3 10.2766 328.9167 32.01
Apatite blue India FTLAB 0.35 12 488 3286 2798 51.39 105.5 8.7907 233.1667 26.52
Bastneasite France FTLAB Internal 12 333 278 -55 42.45 87.6 7.3009 -4.5833 -0.63
Bastneasite France FTLAB 0.25 12 672 704 32 60.31 123.3 10.2766 2.6667 0.26
Bastneasite France FTLAB 0.35 12 488 466 -22 51.39 105.5 8.7907 -1.8333 -0.21
Bucraa Phosphate FTLAB Internal 12 333 694 361 42.45 87.6 7.3009 30.0833 4.12
Bucraa Phosphate FTLAB 0.25 12 672 1562 890 60.31 123.3 10.2766 74.1667 7.22
Bucraa Phosphate FTLAB 0.35 12 488 1048 560 51.39 105.5 8.7907 46.6667 5.31
Burangaite Rwanda FTLAB Internal 12 333 842 509 42.45 87.6 7.3009 42.4167 5.81
Burangaite Rwanda FTLAB 0.25 12 672 1940 1268 60.31 123.3 10.2766 105.6667 10.28
Burangaite Rwanda FTLAB 0.35 12 488 1320 832 51.39 105.5 8.7907 69.3333 7.89
Gabbro Fuerteventura FTLAB Internal 12 333 421 88 42.45 87.6 7.3009 7.3333 1.00
Gabbro Fuerteventura FTLAB 0.25 12 672 865 193 60.31 123.3 10.2766 16.0833 1.57
Gabbro Fuerteventura FTLAB 0.35 12 488 591 103 51.39 105.5 8.7907 8.5833 0.98
KH2PO4 FTLAB Internal 12 333 863 530 42.45 87.6 7.3009 44.1667 6.05
KH2PO4 FTLAB 0.25 12 672 2135 1463 60.31 123.3 10.2766 121.9167 11.86
KH2PO4 FTLAB 0.35 12 488 1577 1089 51.39 105.5 8.7907 90.7500 10.32
Lu2O3 5g FTLAB Internal 12 333 295 -38 42.45 87.6 7.3009 -3.1667 -0.43
Lu2O3 5g FTLAB 0.25 12 672 981 309 60.31 123.3 10.2766 25.7500 2.51
Lu2O3 5g FTLAB 0.35 12 488 933 445 51.39 105.5 8.7907 37.0833 4.22
Mosandrite FTLAB Internal 12 333 852 519 42.45 87.6 7.3009 43.2500 5.92
Mosandrite FTLAB 0.25 12 672 2078 1406 60.31 123.3 10.2766 117.1667 11.40
Mosandrite FTLAB 0.35 12 488 1347 859 51.39 105.5 8.7907 71.5833 8.14
Rosenbushite FTLAB Internal 12 333 805 472 42.45 87.6 7.3009 39.3333 5.39
Rosenbushite FTLAB 0.25 12 672 1527 855 60.31 123.3 10.2766 71.2500 6.93
Rosenbushite FTLAB 0.35 12 488 1138 650 51.39 105.5 8.7907 54.1667 6.16
Sedimentary rock Nonceveux FTLAB Internal 12 333 355 22 42.45 87.6 7.3009 1.8333 0.25
Sedimentary rock Nonceveux FTLAB 0.25 12 672 751 79 60.31 123.3 10.2766 6.5833 0.64
Sedimentary rock Nonceveux FTLAB 0.35 12 488 529 41 51.39 105.5 8.7907 3.4167 0.39
Sedimentary rock Nonceveux FTLAB Internal 12 252 374 122 36.93 76.6 6.3805 10.1667 1.59
Sedimentary rock Nonceveux FTLAB 0.25 12 571 844 273 55.59 113.9 9.4906 22.7500 2.40
Sedimentary rock Nonceveux FTLAB 0.35 12 400 588 188 46.53 95.8 7.9801 15.6667 1.96
Sedimentary rock Nonceveux FTLAB Internal 12 261 360 99 37.58 77.9 6.4895 8.2500 1.27
Sedimentary rock Nonceveux FTLAB 0.25 12 578 833 255 55.93 114.6 9.5472 21.2500 2.23
Sedimentary rock Nonceveux FTLAB 0.35 12 382 558 176 45.47 93.6 7.8036 14.6667 1.88
Shale La Roche FTLAB Internal 12 333 295 -38 42.45 87.6 7.3009 -3.1667 -0.43
Shale La Roche FTLAB 0.25 12 672 616 -56 60.31 123.3 10.2766 -4.6667 -0.45
Shale La Roche FTLAB 0.35 12 488 447 -41 51.39 105.5 8.7907 -3.4167 -0.39
        The small Geiger counter shown on the left has also been tested. Compared to FTLab, this counter has a much higher net counts rate but also a much higher background. It has been used here merely with a 10 hours integration time. The ability of this detector to measure minerals radioactivity is similar to the FTLAB.
10 hours measurement Background Total counts Net counts Critical limit Lc Minimum detectable activity Ratio Net_counts / Min Detect activity
Apatite blue India 52 g 8979 18886 9907 220.44 443.6 22.33
Arfvedsonite Sweden 8979 9657 678 220.44 443.6 1.53
Bucraa phosphate 8979 10225 1246 220.44 443.6 2.81
Burangaite 119.3 g 8979 11656 2677 220.44 443.6 6.03
Gabbro Fuerteventura 122 g 8979 9957 978 220.44 443.6 2.20
Granite lac Fabrège 8979 9049 70 220.44 443.6 0.16
K2HPO4 45g 8979 9697 718 220.44 443.6 1.62
Lutetium probe 8979 11971 2992 220.44 443.6 6.74
Monazite 0.39 g 8979 9857 878 220.44 443.6 1.98
Mosandrite 52.3 g 8979 12491 3512 220.44 443.6 7.92
RbCl 5 g 8979 9162 183 220.44 443.6 0.41
Rosenbuschite 90 g 8979 13205 4226 220.44 443.6 9.53
Sedimentary rock Nonceveux 12 hours 10372 11146 774 236.93 476.6 1.62
Shale La Roche 50 g 8979 9204 225 220.44 443.6 0.51
Xenotime 8979 9491 512 220.44 443.6 1.15
             
100 minutes measurement Background Total counts Net counts Critical limit Lc Minimum detectable activity Ratio Net_counts / Min Detect activity
U3O8 1387 309018 307631 86.64 176.0 1748.04
Thorium Nitrate 1387 127917 126530 86.64 176.0 718.98

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