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