Secondary Ion Mass Spectrometry and R emote Sensing in Space Exploration

1. Gerardo E. Cornejo M. Bonner Denton Scott Tilden Roger Sperline Denton Research Lab Department of Chemistry University of Arizona 07-08 Secondary Ion Mass Spectrometry and Remote Sensing in Space Exploration

2. Outline • Secondary Ion Mass Spectrometer • Function • Objectives • Application to Space Exploration • Remote Sensing • Function • Objectives • Application to Space Exploration

3. Secondary Ion Mass Spectrometer • Works by the principle of charge-to-mass ratio, separation of masses in magnetic sector analyzers –provides quantitative and qualitative analysis • 5 Major Components • Primary ion source • Primary ion column • High vacuum sample chamber • Mass analyzer • Ion detection unit

4. Objectives Increase the sensitivity, stability and dynamic range of Secondary Ion Mass Spectrometry • Current methods to detect ions • Faraday cups • Ion multiplier • Capacitive Trans-Impedance Amplifier Faraday Cups

5. Faraday Cups • Gain is stable and precisely known (gain=1) • Bandwidth is consistent with use in sector-based mass spectrometry • Useful for Iion 10-15 amp (1 ion/sec  1.6  10-15 amps) • Implies that one needs about 6250 ions/sec for detection by Faraday cup Faraday Cage Collector Electrode Out to Amplifier Load Resistor Out to Amplifier

6. Ion Multiplier Operates only when free mean path of the electrons is large ie. a high vacuum Statistically unpredictable

7. CTIA 4 Channel Detector • CTIA is ideal for SIMS • Fast (1 MHz or higher per pixel) • Low read noise • 10,000 x sensitivity improvement over current SIMS detectors • Expect further improvement with 3rd generation differential devices and cooling

8. Differential Capacitive Trans-Impedance Amplifier

9. Custom Ion Detection Devices Developed by the Denton Group • CTIA -1 A 32 channel device adapted from astronomy • CTIA -2 (DM01) A 4 channel single ended input device – demonstrated high sensitivity - but was also highly sensitive to environmental noise • CTIA -3 (DM03) A 128 channel wire bonded mass spec. detector • CTIA -4 A 64 channel wire bonded mass spec. detector with novel noise reduction circuitry by ADIC • CTIA -5 (DM04) A 4 channel differential device designed to reject environmental noise • CTIA -6 (DM013) A 48 channel monolithic electrode mass spec. detector • CTIA -7 (DM016) A 4 channel differential device with X1 & X100 gain levels, programmable bandwidth & advanced low noise input FETs • CTIA -8 (DM 015 ) A512 channel monolithic electrode mass spec. detector (currently under test) • CTIA -9 A 512 channel monolithic – fixes clocking problem on CTIA -8 (under fab) • CTIA -10 A 1696 channel monolithic 12.5 micron pitch mass spec array (under fab) • CTIA – 11 A 4 channel differential with 2 to 4 fold increased sensitivity (under fab)

10. Application to Space Exploration • Currently in use in many missions • “Stardust” mission employs SIMS to perform isotope ratio of oxygen analysis • Used to analyze return samples and obtain chemical composition from mass spectrum

11. Remote Sensing • Diverse forms and methods of applications depending on field of research • Fluorescent tag is placed on object that one may wish to observe • Taggant fluoresces by near IR excitation from laser diodes and/or ambient light and is detected by InGaAs focal plane arrays

12. Objectives • Produce a signal that is observable from a long distance • Vary collection optics to optimize the signal return • Minimize background noise with software controls

13. Applications • Possibility to track errant satellites/spacecraft that have lost communication and also space debris • Applications to tracking animal migration patterns if taggant is placed on animal groups

14. Thank you • Dr. M. Bonner Denton • Dr. Scott Tilden • Dr. Roger Sperline • The Denton Research Group