1. Christine Bradley Mentor: Dr. Denton NASA Space Grant Symposium April 19, 2008 Christine Bradley Mentor: Dr. Denton NASA Space Grant Symposium April 19, 2008 Noise Reduction Techniques

2. Objective With use of a capacitive trans- impedance amplifier (CTIA), an ion detector read out technology, the sensitivity and resolution of a detection instrument can increase as the noise from the environment can be eliminated. Intensity (ADU)

3. Secondary Ion Mass Spectrometer (SIMS) Ion Source Mass Analyzer Detector System Ion Source Mass Analyzer Detector System 3 Components of SIMS

4. Ion Detectors Faraday Cups Useful for I ion 10 -15 amp (1 ion/sec 1.6 10 -19 amps) Implies that one needs about 6250 ions/sec for detection by Faraday cup Electron Multiplier Tube Consist of a series of biased that eject secondary ions when hit by an ion Faraday Cups Useful for I ion 10 -15 amp (1 ion/sec 1.6 10 -19 amps) Implies that one needs about 6250 ions/sec for detection by Faraday cup Electron Multiplier Tube Consist of a series of biased that eject secondary ions when hit by an ion

5. Capacitive Trans-Impedance Amplifier CTIA 4.4 V/e-- 20 E-- read noise @ 77 K Subtracting Environmental Noise Internal noise is still present Internal noise is still present Amplifier Noise from the preamps adds Amplifier Noise from the preamps adds True Differential Amplifier noise is canceled in input stage noise is canceled in input stage True Correlated Subtraction True Correlated Subtraction CTIA 4.4 V/e-- 20 E-- read noise @ 77 K Subtracting Environmental Noise Internal noise is still present Internal noise is still present Amplifier Noise from the preamps adds Amplifier Noise from the preamps adds True Differential Amplifier noise is canceled in input stage noise is canceled in input stage True Correlated Subtraction True Correlated Subtraction

6. Before CTIA Application Blank, Lid ON Base noise level 0.002-0.0025 Blank, Lid OFF Base noise level 0.040-0.050 After CTIA Application Blank, Lid ON Base noise level 0.003-0.004 Blank, Lid OFF Base noise level 0.0035-0.004 After CTIA Application Blank, Lid ON Base noise level 0.003-0.004 Blank, Lid OFF Base noise level 0.0035-0.004 Results

7. Thank You Questions?