Calibrating GEM detector
Amplifier effect on the signal
Ortec 474 timing filter amplifier amplifies the signal from the trigger output.The amplification will make a shift in the channel number compared to the same signal without application. To determine exactly the shift in channel number after the amplification, a choice for an input signal amplitude to charge the ADC just above noise, then amplifying the same input then recording the channel number (if possible). For example, generating a pulse of 0.1 V amplitude with an offset of 0.06 V using stanford research system pulse generator DG535 will hit channel 291 +_0.34 (run#4829), after the amplification it hits channel number 3767 +_0.78. Input pulse for the attenuator is 1.80V +_ 0.045, and the attenuator output pulse is 222 +_ 2.5 mV (factor of 8.1) when is set on 17.5 dB.
Amp + att. 04/26/13
| Run Number | attenuation (dB) | Amplification | Average channel Number | Average channel Number - Noise (79) | calculated gain | Notes |
| 4853 | 0 | 0 | 880 | 801 | 0 | reference for the next two |
| 4854 | 2 | 0 | 553 | 474 | 4.6 | |
| 4855 | 4 | 0 | 304 | 225 | 11.0 | |
| 4860 | 0 | 0 | 3399 | 3320 | 0 | |
| 4861 | 14 | 0 | 98.46 | 19.46 | 44.6 | |
| 4862 | 0 | 0 | 3514 | 3435 | 0 | |
| 4863 | 14 | 0 | 133 | 54 | 36.1 | |
| 4868 | 0 | 0 | 3903 | 3824 | 0 | |
| 4869 | 14 | 0 | 114 | 35 | 40.8 | |
| 4872 | 0 | 0 | 2974 | 2895 | 0 | |
| 4846 | 24.5 | yes | 436 | 357 | 18.2 | |
| 4848 | 18 | yes | 1720 | 1641 | 4.9 | |
| 4849 | 20 | yes | 1213 | 1134 | 8.1 | |
| 4850 | 14 | yes | 3210 | 3131 | -0.7 | |
| 4851 | 16 | yes | 2365 | 2286 | 2.1 |
Att. 04/27/13
unamplified input pulse passed through an attenuator, the attenuation is changed (without changing the input pulse offset of the input), the results are in the following table:
| Run Number | attenuation (dB) | Average channel Number | Average channel Number - Noise (79) | calculated gain |
| 4894 | 0 | 3653 | 3574 | 0 |
| 4897 | 8 | 1104 | 1025 | 10.8 |
| 4898 | 9 | 916 | 837 | 12.6 |
| 4899 | 6 | 1531 | 1452 | 7.8 |
| 4898 | 3 | 2380 | 2301 | 3.8 |
Amp 04/28/13
- Amplified x4 level 4 fine gain
| Run Number | attenuation (dB) | Average channel Number | Average channel Number - Noise (79) | calculated gain |
| 4905 | 0 | 3779 | 3700 | 0 |
| 4906 | 3 | 2580 | 2501 | 3.4 |
| 4907 | 6 | 1776 | 1679 | 6.8 |
| 4908 | 9 | 1124 | 1045 | 10.9 |
| 4909 | 12 | 626 | 547 | 16.6 |
| 4910 | 15 | 287 | 208 | 25 |
| 4911 | 18 | 99 | 20 | 42.6 |
Amp and att. 05/04/13
- Amplified x6 level 6 fine gain
- With attenuator
According to the calibration curve above the charge collected by the ADC is determined in the table above.[https://wiki.iac.isu.edu/index.php/Neutron_TGEM_Detector_Abdel#Run_List3 ]
Att. 05/10/13 & 06/03/13
The table below shows the measurements of the charge of a square pulse that has an amplitude of -0.49 V (osc. 0.504+_ 0 V )with a zero offset and a width of 25.2us. The gate width is 70ns.
| Run Number | attenuation (dB) | Average channel Number | Pedestal subtracted Average channel Number | calculated gain |
| 5120 | 0 | 3876.27 | 3797 | 0 |
| 5120 | 3 | 3057 | 2977 | |
| 5123 | 6 | 1906 | 1827 | |
| 5124 | 9 | 1339 | 1260 | |
| 5125 | 12 | 940 | 861 | |
| 5126 | 14 | 742 | 663 | |
| data2 06/03/13 | ||||
| 5172 | 0 | 3818.94 +/- 0.06 | ||
| 5173 | 3 | 2685.03 +/- 0.05 | ||
| 5174 | 6 | 1889.48 +/- 0.05 | ||
| 5176 | 9 | 1322.00 +/- 0.03 | ||
| 5177 | 12 | 926.62 +/- 0.03 | ||
| 5178 | 15 | 647.03 +/- 0.02 |
Amp 06/03/13
- Amplifier
An amplifier (x6 level 6) was added to amplify the signal before attenuation, a square pulse of an amplitude of (1st time-0.18V) and for (the second time 0.47V) (osc. 235 +_ 4 mV) with a zero offset and a width of 25.8us was used, the gate width was 70ns. After the amplification the signal amplitude is (first time 3.42+_ 0.29 V) (2nd time: gate integrate 4.21 +/-0 V).
| Run Number | attenuation (dB) | Average channel Number | Average channel Number - Noise (79) | charge collected (nC) | calculated attenuation | expected attenuation | V(mV) |
| 5134 | 14 | 3952 | 3873 | 1.6552 | 0 | 647+_32 | |
| 5135 | 15 | 3503 | 3424 | 1.4756 | 0.997 | 576+_27 | |
| 5136 | 18 | 2474 | 2395 | 1.064 | 20*log(3952/2472) = 4.2 | 4 | 416+_16 |
| 5137 | 21 | 1752 | 1673 | 0.7752 | 6.589 | 235+_ 32 | |
| 5138 | 24 | 1206 | 1127 | 0.5568 | 20*log(3873/1127) = 10.7 | 10 | 222 +_7 |
| Data2 | 06/03/13 Pedestal 63 | ||||||
| 5180 | 14 | 2872.76 +/- 0.09 | 872 | ||||
| 5181 | 15 | 2477.22 +/- 0.08 | 782 | ||||
| 5182 | 18 | 1823.29 +/- 0.08 | 546 | ||||
| 5183 | 21 | 1306.90 +/- 0.04 | 392 | ||||
| 5184 | 24 | 933.94 +/- 0.03 | 271 |
Bat. 05/24/13
- ADC calibration using a battery
Using a 1.5V battery connected to to 5 kohm resistor, then 25 ohm terminated ADC. The oscilloscope measures 15 mV DC voltage for the battery as it is 50 ohm terminated.
| Run Number | channel Number | Channel Number - padestal | Gate width (ns) | Charge (nC) |
| 62 | 851 | 771 | 500 | 0.015*(Gate width)/25 = 0.3 |
| 63 | 1263 | 1184 | 750 | 0.45 |
| 64 | 1702 | 1623 | 1000 | 0.6 |
| 65 | 1250 | 2072 | 2151 | 0.75 |
| 66 | 2500 | 3897 | 3976 | 1.5 |
Bat 05/30/13
- ADC calibration using a battery
Using a 1.5V battery with a grounded positive terminal connected to to 5 kohm resistor, then 50 ohm terminated ADC. The oscilloscope measured 14.4 mV DC voltage of the battery when it is 50 ohm terminated.
| Run Number | channel Number +_ error | Gate width (ns) | charge (nC) |
| 97 | 865 +_ 0.04 | 500 | =0.0144*(Gate width=500)/50=0.144 |
| 98 | 493+_0.03 | 250 | 0.072 |
| 101 | 1283 +_0.03 | 750 | 0.216 |
| 102 | 1000 | ||
| 104 | 2105 +_ 0.04 | 1250 | 0.36 |
| 106 | 3317 +_ 0.02 | 2000 | 0.576 |
| 107 | overcharge | 2500 |
- Measurements Notes
1- The slope of the calibration curve as the ADC is connected to the battery with the positive terminal grounded is 178 pC.
2- The ADC manual manual mentioned 100pC gain/count, does count = channel? Also it is measures max. tolerate voltage >25 mV with +_ 2 mV as maximum voltage offset, the battery provides 14.4 mV offset, Does the ADC measure that the battery voltage or consider it more that the offset limit and measure only within the offset limit?
Today 05/31 the equipment moved to the LDS to start our measurements but I am still thinking how to improve our calibration curve measurements to get the right slope.
Bat. grounded 6/2/13
Measuring the grounded positive terminal battery output again in the LDS, V= 14.7 mV measured by the oscilloscope. (R= 5kohm, V=1.5, I= 1.5/5kohm = 0.3 mA, oscilloscope channel 2 is 46 ohm terminated, then V = 46*0.3mA = 13.8 mV). The ADC noise level in channel 5 (signal channel) is 63 (run #5162) which is 42.1 ohm terminated.
| Run Number | channel Number +_ error | channel Number - Pedestal | Gate width width (ns) | charge (pC) |
| 5161 | 356.14 +/- 0.01 | 293 | 178 | = 14.7*(Gate width)/42.1 = 62.2 |
| 5163 | 712.09 0.02 | 649 | 398 | 139.0 |
| 5164 | 1368.60 +_ 0.02 | 1305 | 798 | 278.6 |
| 5165 | 2662.70 +_ 0.02 | 2600 | 1592 | 555.9 |
| 5157 | 3670 +_ 0.01 | 3607 | 2216 | 773.8 |
Amp 06/04/13
- Amplified x6 level 6 fine gain
stanford pulse generator is used as source for a negative pulse of width of 11.8us +/- 3, and the gate width is 32.94 ns +/- 0.02 . all the voltage measurement is recorded by using oscilloscope 46 ohm terminated. So the amplifier input current is (input signal amplitude/46)
| Run Number | input signal (mV) | amplified pulse amp. (mV) +/- SD | Charge (pC) | Average channel Number | Average channel Number - Noise (63) |
| 5205 | 51 +/- 1 | 676.702 | 945 +/- 8 | 2415.57 +/- 0.13 | 2352.57 |
| 5207 | 56 +/- 1 | 744.730 | 1040 +/- 8 | 2644.05+/- 0.10 | 2581.05 |
| 5208 | 60 +/- 1 | 809.178 | 1130 +/- 10 | 2840.40+/- 0.15 | 2777.40 |
| 5209 | 65 +/- 1 | 859.304 | 1200 +/- 8 | 3066.89+/- 0.18 | 3003.89 |
| 5210 | 70 +/- 1 | 916.591 | 1280 +/- 8 | 3293.51+/- 0.21 | 3230.51 |
| 5214 | 80 +/- 1 | 1045.49 | 1460 +/- 8 | 3744.33+/- 0.15 | 3681.33 |
Two Amp's 06/06/13
- Amplified x6 level 6 fine gain and P.S. gain amplifier 777
stanford pulse generator is used as source for a negative pulse of width of 892 ns +/- 4, and the gate width is 32.7 ns +/- 0.6 . all the voltage measurement is recorded by using oscilloscope 46 ohm terminated. So the amplifier input current is (input signal amplitude/46)
| Run Number | input signal (mV) | amplified pulse amp. (V) +/- SD | Charge (pC) | Average channel Number | Average channel Number - Noise (63) |
| 5253 | 21.6 +/- 0.3 | 0.79 +/- 0.01 | 1847.32 +/- 0.13 | ||
| 5254 | 23.6 +/- 0.3 | 0.86 +/- 0.01 | 2305.25 +/- 0.14 | ||
| 5255 | 25.6 +/- 0.3 | 0.94 +/- 0.01 | 2501.55 +/- 0.12 | ||
| 5256 | 27.6 +/- 0.3 | 1.02 +/- 0.01 | 2696.81 +/- 0.18 | ||
| 5257 | 29.6 +/- 0.3 | 1.09 +/- 0.01 | 2899.58 +/- 0.16 | ||
| 5258 | 37.3 +/- 0.3 | 1.40 +/- 0.01 | 3695.65 +/- 0.14 |
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