secondary ion mass spectrometry and r emote sensing in space exploration
DESCRIPTION
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 R emote Sensing in Space Exploration. Outline. Secondary Ion Mass Spectrometer Function Objectives - PowerPoint PPT PresentationTRANSCRIPT
Gerardo E. CornejoM. Bonner DentonScott TildenRoger SperlineDenton Research LabDepartment of Chemistry University of Arizona 07-08
Secondary Ion Mass Spectrometer Function Objectives Application to Space Exploration
Remote Sensing Function Objectives Application to Space Exploration
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
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
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 CageFaraday CageCollector ElectrodeCollector Electrode
Out to AmplifierOut to Amplifier
Load ResistorLoad Resistor
Out to AmplifierOut to Amplifier
Operates only when free mean path of the electrons is largeie. a high vacuum
Statistically unpredictable
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
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)
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
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
Produce a signal that is observable from a long distance
Vary collection optics to optimize the signal return
Minimize background noise with software controls
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
Dr. M. Bonner DentonDr. Scott Tilden Dr. Roger SperlineThe Denton Research Group