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Analytical characteristics of new Faraday amplifier boards equipped with 1e11 and 1T resistors for use in high precision TIMS isotope ratio measurements
Zenon Palacz, Isotopx Ltd, Middlewich, Cheshire, UK Introduction Thermal Ionization Mass Spectrometers (TIMS) are capable of generating the highest precision and accuracy in isotope ratio determinations. Low mass bias, accurate mass fractionation corrections, high sensitivity and the absence of isobaric interferences are key contributions to a TIMS performance. However, the ability to quantitatively measure ion…
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Total evaporation analysis (TE) of 500ng loads of U500 using Phoenix TIMS – Precision and Efficiency.
Zenon Palacz, Isotopx Ltd, Middlewich, Cheshire, UK Introduction Uranium does not have a stable isotope pair that can be used to correct for mass fractionation in a TIMS. Measurements have to be made using external mass fractionation control or by total evaporation of the sample and simultaneous (static) collection of all isotopes. Addition of a…
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Measurement of NBS U010, NBL U030a and NBL U050 uranium standards by total evaporation using the Phoenix TIMS.
Zenon Palacz, Isotopx Ltd, Middlewich, Cheshire, UK Introduction Although Uranium lacks a stable isotope pair, a number of external techniques are available to correct for the mass fractionation that occurs during TIMS analysis. The ‘gold standard’ methodology is to add a 233U-236U double spike to the sample and use this to calculate the mass fractionation….
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Determination of 234U and 236U in IRMM184 Uranium Standard on the Phoenix Thermal Ionization Mass Spectrometer
Introduction IRMM 184 has an extremely low level of 236U (0.12ppm relative to 238U) and a high quality analysis of this minor isotope requires the use of an ion counting detector equipped with a retarding filter. Application Brief G20111 describes a multi-step analysis routine combining Faraday and Daly ioncounting to measure 234U/238U and in this…
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Determination of 234U in IRMM184 Uranium Standard on the Phoenix Thermal Ionization Mass Spectrometer
Introduction High precision measurements of 234U/238U are necessary for U-series applications in geological research. Typically, 234U is a low abundance isotope and must be determined with an ion counting detector whilst 238U is the most abundant isotope and must be determined on a Faraday collector. This note describes the performance of the Phoenix TIMS for…
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Multidynamic measurement of small Neodymium (Nd+) ion signals on Faradays using Xact amplifiers with 1e11 Ω and 1e12 Ω (1T) resistors
Introduction Thermal Ionization Mass Spectrometry is an extremely sensitive detection technique. For Neodymium, measured as Nd+ , ion yields of 1 ion per 50 atoms loaded are typical for triple filament geometries on a Phoenix TIMS. This efficiency is of huge importance for applications where there is very little sample material e.g. garnet growth rims…
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An assessment of the linearity of the ion-counting Daly detector and Hamamatsu photomultiplier using NBS U500
Zenon Palacz, IsotopX Ltd, Middlewich, Cheshire, UK The Daly detector was designed by N.R Daly in the 1960s. The design uses a conversion dynode to convert incident ions into electrons. It also separates the multiplication electronics away from the ion beam preventing secondary ion production on the multiplication dynodes. The conversion surface is a highly…
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Noise Characteristics of Phoenix TIMS Xact Faraday Detectors with 1 x 10e11 ohm resistors
Introduction High precision isotope ratios require an optimal signal to noise ratio. Here we assess the electronic noise of the new Xact Faraday detectors on Phoenix TIMS using a range of different integration times and compare the results to the theoretical noise calculated from the Johnson law. Experimental Phoenix has nine Faraday collectors each directly…
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Multidynamic measurement of small Neodymium (Nd+) ion signals on Faradays using Xact amplifiers with 1e11 Ω and 1e12 Ω (1T) resistors
Zenon Palacz, Davydd Wanless, Ian Turner & Tony Jones. Isotopx Ltd. UK Introduction Thermal Ionization Mass Spectrometry is an extremely sensitive detection technique. For Neodymium, measured as Nd+ , ion yields of 1 ion per 50 atoms loaded are typical for triple filament geometries on a Phoenix TIMS. This efficiency is of huge importance for…