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Encyclopedia of Spectroscopy and Spectrometry || Accelerator Mass Spectrometry (AMS)
摘要： Accelerator mass spectrometry (AMS) was developed for analyzing 14C in environmental and archeological specimens in the 1970s (although it was first demonstrated in the 1930s). It is now principally used to measure only a handful of isotopes, although it is feasible to apply it to many additional analytes. AMS represents the marriage of high-energy physics with radioanalytical chemistry and finds applications in geoscience, environmental analysis, archeology, cosmochemistry, biosciences, medicine, material science, nuclear chemistry, and physics. AMS employs a high-energy tandem accelerator to raise ion energies to the mega-electron-volt (MeV) range and enable complete destruction and avoidance of isobaric interferences. Typical AMS is thus capable of measuring very small isotope ratios, typically in the range of 10^-15 (atomic ratio). Isotopes of interest include 14C, 10Be, 26Al, 36Cl, 41Ca, and 129I. Measured rare/natural ratios for these isotopes fall well below the 1–10^-9 range measured with other mass spectrometers (except for laser-based systems with resonance ionization techniques, which can match the range of the AMS).
关键词： radioanalytical chemistry,AMS,high-energy physics,isotopes,Accelerator Mass Spectrometry
更新于2025-09-04 15:30:14
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The Phase1 CMS Pixel detector upgrade
摘要： The pixel detector of the CMS experiment will be replaced in an extended end-of-year shutdown during winter 2016/2017 with an upgraded one able to cope with peak instantaneous luminosities beyond the nominal LHC instantaneous luminosity of 1 × 1034 cm?2 s?1. Under the conditions expected in the coming years, which will see an increase of a factor two in instantaneous luminosity, the present system would experience a dynamic ine?ciency caused mainly by data losses due to bu?er over?ows. The Phase I upgrade of the CMS pixel detector, described in this paper, will operate at full e?ciency at an instantaneous luminosity of 2 × 1034 cm?2 s?1 and beyond, thanks to a new readout chip. The new detector will feature one additional tracking point both in the barrel and in the forward regions, while reducing the material budget as a result of a new CO2 cooling system and optimised layout of the services. In this paper, the design and the technological choices of the Phase I detector will be reviewed and the status of the construction of the detector and the performance of its components will be discussed.
关键词： Particle tracking detectors,Radiation-hard detectors,Performance of High Energy Physics Detectors,Si microstrip and pad detectors
更新于2025-09-04 15:30:14