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Upgrading an extraction and purification line for measuring terrestrial cosmogenic noble gases

English title Upgrading an extraction and purification line for measuring terrestrial cosmogenic noble gases
Applicant Schlunegger Fritz
Number 163994
Funding scheme R'EQUIP
Research institution Institut für Geologie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Geology
Start/End 01.01.2016 - 31.12.2016
Approved amount 60'000.00
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Keywords (4)

Geomorphology; cosmogenic noble gas; Earth's surface erosion; extraction line facility

Lay Summary (German)

Lead
Massensprektrometer zur Bestimmung kosmogen gebildeter Edelgase
Lay summary

Wir planen, das am Institut bereits vorhandene Massenspektrometer so umzubauen, dass kosmogen gebildete Edelgase an terrestrischen Proben gemessen werden können. Damit wird es möglich sein, Abtragungsraten über grössere zeitliche Skalen zu messen. Des weiteren planen wir, mit Hilfe des ausgebauten Messinstrumentes paläoaltimetrische Untersuchungen durchführen zu können.

Direct link to Lay Summary Last update: 03.12.2015

Responsible applicant and co-applicants

Collaboration

Group / person Country
Types of collaboration
Prof. Ingo Leya, Institute of Physics, UniBe Switzerland (Europe)
- Research Infrastructure
- Exchange of personnel
Prof. Igor Villa, Institute of Geological Sciences, UniB Switzerland (Europe)
- Research Infrastructure
Prof. Klaus Mezger, Institute of Geological Sciences, UniBe Switzerland (Europe)
- Research Infrastructure
- Exchange of personnel

Associated projects

Number Title Start Funding scheme
148191 Tropical volcanic islands erosion and landscape evolution - Earth surface geochronology, morphometry and numerical modeling 01.10.2013 Ambizione
170559 GlaciEr-Alps: Glacier dynamics, erosion patterns and Alpine paleoclimate over the last glacial cycle 01.04.2017 SNSF Professorships
155892 Erosional history of the Western Andean Escarpment between Northern Peru and Northern Chile 01.01.2015 Project funding (Div. I-III)
153053 Climate history of the Indo-Pacific region and subsurface biosphere of Lake Towuti: The Swiss contribution to the ICDP Towuti Drilling Project (research part) 01.01.2015 Project funding (Div. I-III)

Abstract

We plan to upgrade a noble gas extraction and purification system to be coupled to the MAP 215-50 mass spectrometer hosted by the Institute of Geological Sciences at the University of Bern. This instrument will be used for measuring cosmic-ray-produced helium-3 (3He) and neon-21 (21Ne) to quantify processes on Earth’s surface. The high sensitivity, low background and high mass resolution that are required for terrestrial samples indeed require an instrument that is explicitly dedicated for the measurements of terrestrial cosmogenic 3He and 21Ne.In the past years, terrestrial cosmogenic nuclides have been successfully used for measuring erosional processes on Earth’s surface. In this context, quantifications of landscape change have mainly been accomplished through the use of radioactive cosmogenic nuclides such as 10Be and 26Al, but their application has been restricted to Quaternary time scales because of their relatively short half lives. The results are 10Be and 26Al concentrations that are below the detection limit of available accelerator mass spectrometers if the samples have a Late Miocene or even a Pliocene age. Contrariwise, cosmogenic noble gases such as 3He and 21Ne do not experience any radioactive decay through time, which places these isotopes in an unbeatable position for measuring paleo-erosion rates preserved in detrital material even if the ages of these deposits are up to 10 Ma and even older. This is the major motivation why we decided to build a noble gas extraction and purification system, to couple this equipment to the MAP 215-50 mass spectrometer hosted by the Institute of Geological Sciences at the University of Bern, and finally to measure these isotopes with the upgraded system. Once in operation, the equipment will be used to (i) measure paleo-erosion rates in several places around the globe (e.g., in the framework of SNF projects with a focus on the Andes, Indonesia and in environments where the bedrock is made up of volcanic rocks), (ii) reconstruct the history of surface erosion rate in response to global cooling during the past c. 10-5 My, (iii) determine paleo-temperatures for low-T conditions, and (iv) quantify elevations of paleo-topographies through time. The financial budget includes components to build a new all-metal extraction and purification line, which comprises: (i) a sample loading-chamber equipped with a carrousel that will be placed on top of the existing double vacuum resistance furnace, (ii) an ultra high vacuum pumping system (<10-8 mbar) that will be composed of a turbo-molecular pump (Pfeiffer) and an ion pump (Agilent Technologies), (iii) the line itself made up of a series of valves, connectors, getter fingers filled with titanium foam and activated charcoal cold-traps, (iv) a dry-cryogen free cryostat system (ICEoxford Ltd) operating at temperatures ranging between 8K and 375K for trapping gas such as He, Ne, Ar, Kr and Xe, and (v) a vacuum crusher. This upgraded facility will allow gaining in measurement sensitivity and also in detection level. The line will be built with technical and scientific support by colleagues from the noble gas geochemistry group at the Physics Department.
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