Pacific Centre for Isotopic and Geochemical Research
Department of Earth, Ocean and Atmospheric Sciences,The University of British Columbia
Nu TIMS | Nu TIMS NT015 | VG54R and VG354S TIMS
The Nu TIMS was installed at PCIGR in November 2014 and was first TIMS commercially produced by Nu Instruments Ltd. (UK). It was designed as part of a collaborative research and development partnership between PCIGR and Nu that aims to improve analytical techniques and instrument design for the benefit of the scientific community.
The Nu TIMS is equipped with variable dispersion multi-collector technology to improve the versatility and overall performance of this long established analytical technique. Combining advances in filament assembly, ease of use and high precision, the Nu TIMS uses a patented Zoom lens system to ensure perfect peak alignment without needing to move the detectors. The Nu TIMS is equipped with an ion-counting mini Daly and an ion counter capable of precisely measuring small samples and low abundance isotopes, and so provides ultimate stability and dynamic range.
The Nu TIMS at PCIGR is used to measure Sr and Nd isotopic ratios. In 2015, in static mode, the average values for NBS 987 300ng was 0.710229 ± 26 (n=23) and for JNdi 100ng was 0.512121 ± 39 (n=12). In dynamic mode the average for NBS 987 300ng was 0.710250 ± 8 (n=19) and for JNdi 100ng was 0.512107 ± 11 (n=11). The 2017–2018 average for NBS 987 was 0.710237 ± 21 (n=71).
We are also experimenting with analyses with much smaller sample loads, down to <10ng for Sr and <20ng for Nd.
PCIGR actively monitors the performance of this high-precision instrument through the analyses of standards (e.g., SRM 981, JMC-475, La Jolla or JNdi) and reference materials (USGS and others). To review our on-going monitoring efforts and performance over the years, please visit the Isotopic Analysis page.
A second Nu TIMS was installed in 2022 for the purpose of high-precision U-Pb geochronology at PCIGR.
This Nu TIMS is equipped with an ion-counting Daly detector, with measurement stability, linearity and dynamic range that can be used for the precise measurement of small samples and low-abundance isotopes, such as 204Pb in zircon. The collector block is fitted with 16 Faraday cups that are arranged for static Faraday U analysis as well as Faraday-Daly dynamic Pb runs for large sample sizes.
The Nu TIMS is comes with electronically switchable amplifiers, including 1011-ohm resistors for large ion beams, and 1012-ohm resistors for enhanced signal-to-noise ratios on small ion beam measurements. The electronically switchable pre-amp bin allows for the greatest flexibility in analyzing a wide dynamic range of sample sizes with minimal downtime (<1 hr).
We use this Nu TIMS exclusively for single-grain CA-TIMS U-Pb analysis of zircon and a variety of U-Pb accessory phases (e.g., baddeleyite, titanite, rutile, and apatite). This instrument advances the capabilities of PCIGR’s geochronology facility and supersedes our VG54R and VG354S TIMS instruments.
With the installation of this state-of-the-art Nu TIMS, we are now equipped with a high-sensitivity mass spectrometer for U-Pb ID-TIMS geochronology, as well as one of the cleanest TIMS for analysis of radiogenic Pb/U ratios in accessory minerals such as zircon.
The total common Pb of our zircon analyses reflects blank contributions from the laboratory at <0.3 pg, as determined by quality control. The low procedural blanks allow for analysis of single zircon grains as young as the Pleistocene. We can also pluck fragments of zircon grains from grain mounts previously analyzed by in-situ methods and analyze the fragments by ID-TIMS at an instrument precision of <0.1% (2-sigma).
VG54R
The Micromass VG54R single-collector TIMS was purchased in 1982 with NSERC support and underwent major upgrades in 1987 and 1995. It is currently configured with a Faraday collector and Daly photomultiplier, the latter for low-level U-Pb analyses (<1 ng radiogenic Pb), digital voltmeter and an automated 16-sample turret.
This instrument is now primarily used to determine Pb and U blanks from in-house produced ultra-pure reagents, as well as to determine blanks for common Pb and U-Pb studies. It is also used for single-grain zircon chemical abrasion (CA-TIMS) U-Pb, U-Pb accessory phase analysis, and for common Pb analysis of sulphide minerals and feldspar.
VG354S
This single-collector TIMS instrument with Sector 54 electronics was acquired in 2008 from the University of California at Berkeley. This TIMS is currently configured with an automated 20-sample turret, an oversized Faraday collector (originally acquired to facilitate Ca isotopic analyses), an analogue Daly collector used for low level U-Pb analyses, a digital voltmeter, and digital pyrometer. It is operated with the most recent version of Sector 54 software.
Since 2009 this instrument has been used exclusively for single-grain CA-TIMS U-Pb analysis of zircon, and a variety of U-Pb accessory phases.
Both of these instruments support the PCIGR geochronology lab, which conducts ID-TIMS U-Pb analysis on zircon (CA-TIMS single-grain work) and other U-Pb accessory phases including baddeleyite, monazite, titanite, allanite, garnet, apatite and rutile, from rocks of ultramafic through felsic compositions.
The PCIGR geochronology lab has been involved with the EARTHTIME initiative since 2006. During that year we acquired the three U-Pb reference solutions made available for spike calibration and used them to recalibrate the UBC mixed 205Pb-233-235U isotopic tracer.
In 2008 we acquired and began to analyze the EARTHTIME synthetic solution reference materials (100Ma, 500Ma and 2Ga). We continue to routinely analyze these solutions to the present time. In June 2010 we received our first aliquot of ET535 spike, and in September 2015 we received a refill of this EARTHTIME isotopic tracer. This spike is used for much of the U-Pb geochronology work conducted in the lab.
Since PCIGR was established in January 2002, and through to July 2018, the UBC U-Pb group has produced >6500 U-Pb isotope dilution analyses (from more than 1200 rock samples), >2400 sulphide mineral common Pb isotopic compositions, and >2600 U-Pb standard and blank analyses.