Advances in secondary ion mass spectroscopy

TL;DR

This paper discusses improving the accuracy of secondary ion mass spectrometry (SIMS) measurements of nitrogen in niobium, crucial for superconducting RF cavities, by investigating factors affecting relative sensitivity factors (RSF).

Contribution

It identifies key factors influencing RSF measurements and demonstrates methods to achieve better than 10% accuracy in nitrogen quantification in niobium.

Findings

Achieved >10% accuracy in nitrogen measurement in niobium.

Identified critical factors affecting RSF measurement reliability.

Provided guidelines for precise SIMS analysis in SRF materials.

Abstract

Accurate SIMS measurement of nitrogen in niobium relies on the use of closely equivalent standards, made by ion implantation, to convert nitrogen signal intensity to nitrogen content by determination of relative sensitivity factors (RSF). Accurate RSF values for ppm-range nitrogen contents are increasingly critical, as more precision is sought in processes for next-generation superconducting radio-frequency (SRF) accelerator cavities. Factors influencing RSF value measurements were investigated with the aim of reliably attaining better than 10% accuracy in N concentrations at various depths into the bulk. This has been accomplished for materials typical of SRF cavities at the cost of great attention to all aspects.