Salient_Characteristics_9_17_26_RJM_(1)_0001.docx

PR # xxxxxxx Title: Noble gas mass spectrometer for 40Ar/39Ar geochronology and cosmogenic neon geochronology

Laboratory: Bascom Argon Dating Laboratory

Specifications/Salient Characteristics:

We require a noble gas mass spectrometer capable of simultaneous multi-collection of the 5 mass positions required for 40Ar/39Ar analysis (mass 36-40) and capable of simultaneous multi-collection of the 3 mass positions required for cosmogenic neon geochronology (mass 20-22). The instrument must also be capable of measuring the mass positions required for all isobaric interferences required for cosmogenic neon geochronology (e.g 18, 19, 40, 44). Further specifications are given below and in the performance work statement.

The instrument needs to include the following:

Detectors:

Argon: We require detectors for simultaneous acquisition of 5 argon peaks (40, 39, 38, 37, 36). The collectors for M/e of 40, 39, 38, and 37 should include faraday detectors with amplifiers capable of electronic intercalibration. For faraday collectors we require noise @ 10 second integration time of < 1E-17 amps, and a decay time (tau) to 10 ppm of < 0.3 seconds. The collector(s) for M/e 36 must include a multiplier of the discrete dynode type, and the specifications of the multiplier must be included in the proposal. There must be design capabilities to intercalibrate the detectors. See performance work statement for additional details.

Neon: We require detectors for simultaneous acquisition of 3 neon peaks (22, 21, 20). The collectors for M/e of 22 and 20 can be faraday detectors with amplifiers capable of electronic intercalibration and/or multipliers of the discrete dynote type. For faraday collectors we require noise @ 10 second integration time of < 1E-17 amps, and a decay time (tau) to 10 ppm of < 0.3 seconds. The collector(s) for M/e 21 must include a multiplier of the discrete dynode type, and the specifications of the multiplier must be included in the proposal. There must be designed capabilities to intercalibrate the detectors. There must be designed capabilities to precondition the electron multiplier to reduce potential CO2 release from this component (e.g. Gyore et al. 2021). Capability for multi-collection of mass 40 and 44 (species required for isobaric interference corrections, 40Ar+ and 44CO2) is desired but not required. See performance work statement for additional details.

Emission Regulator/Source Control Total emission current must be stable to 100ppm. Additionally, the hardware must permit switching ionization off during gas inlet and equilibration to avoid fractionation prior to measurement. Ionization shutoff is a critical component we require to allow for extended gettering without gas consumption. This could help mitigate CO2 interferences on Neon, among other issues.

Transition Between Argon and Neon Analytical Setups We seek an instrument that can routinely be used for multicollection of isotopes of both Argon and Neon. Ideally, as in the beam separation, the transition between the two analytical setups will require only changes to the electromagnet and source settings; which can be controlled by software and are reproducible. If additional changes to the instrument setup (e.g. physical movement of the magnet) are required those must be fully described—and the method of reproducing any manual movements described, proven, and documented in detail—such that routine transitions between Argon and Neon are achievable. Routine here is defined as transitioning the mass spectrometer from the Argon to the Neon setup such that a multi-collection measurement of Neon isotopes in air can be made the following day.

Pumping System Roughing system must be oil-free to prevent hydrocarbon contamination. An ion pump designed to pump noble gas is required as the ultra-high vacuum pump. All pumps must be pneumatically isolatable from the analyzer to allow automated, static measurement. An ultimate pressure of less than 1x10-9 torr must be attained. If pumping is required on the collector housing, the pump must be vibrationally isolated.

Software/Data Acquisition:

The instrument must be delivered with computer-controlled source, magnet and collector electronics as well as data acquisition software. The program must use industry-standard communication protocols with electronic components. The program must provide an accurate time-base for all data acquisition operations, control all necessary peak-switching, perform peak centering, acquire background diagnostics, linearly regress peak intensities to inlet time with appropriate background and intercept statistics. The program must provide the capability to switch ionization off during gas inlet and equilibration to avoid fractionation prior to measurement. The relevant commands must also be provided such that custom in-house software can employ this functionality. The program must allow for integration with LabView and Python softwares that may operate the argon extraction line valves and laser