Principal characteristics of the facility and of the support offered to users: The Low Temperature Laboratory LTL at the Helsinki University of Technology, 7 km west of the center of Helsinki, offers expertise, facilities, and equipment for outside Users to undertake measurements at temperatures from 4 K down to the lowest attainable to date. The Large-Scale Facility ULTI II, a continuation of the present HCM ULTI, expects to contribute to scientific progress and technical development of ultra low temperature physics in Europe, to serve as a first-rate educational center for young physicists and, because of its long-standing connections with low temperature research in the east, to act as a node for scientific collaboration between Russia and the EU countries. The in-house research includes experimental programs on i refrigeration and cryogenics in the liquid helium range and below, and ii studies of quantum fluids and solids, iii nuclear magnetism, and iv electrical transport in normal and superconducting structures of nanometer size. The low temperature section of the LTL consists of 28 researchers of whom 3 are professors, 4 docents, and 2 more junior PhD level scientists; the rest are graduate or undergraduate students. Technical and clerical employees amount to 6 persons. The ULT refrigeration equipment includes three cryostats with a 3He-4He dilution refrigerator for precooling a copper nuclear demagnetization stage. The third is a cascade refrigerator with two nuclear cooling stages in series; many world-records of low temperature have been made with this machine. Smaller cryostats are available for test experiments down to 20 mK.
Helium solubility in olivine and implications for high 3He/4He in ocean island basalts
Projects helium-tritium dating of groundwater: various cooperations distribution of radiogenic 4He in groundwater helium isotopes distributions in the Weddell Sea helium isotopes from hydrothermal vent sites. De la Torre, M. Mudarra, J. Andreo , Complementary use of dating and hydrochemical tools to assess mixing processes involving centenarian groundwater in a geologically complex alpine karst aquifer, Hydroligical Processes, june , doi Calvache, M.
Automated He Extraction Line for (U-Th)/He Dating Blazers Prisma QMS quadrupole mass spectrometer for measuring 3He/4He ratios.
This summary serves as the basis for the extraction of the alpha particle charge radius from the muonic helium Lamb shift measurements at the Paul Scherrer Institute, Switzerland. Individual theory contributions needed for a charge radius extraction are compared and compiled into a consistent summary. The influence of the alpha particle charge distribution on the elastic two-photon exchange is studied to take into account possible model-dependencies of the energy levels on the electric form factor of the nucleus.
We also discuss the theory uncertainty which enters the extraction of the 3 He— 4 He isotope shift from the muonic measurements. The theory uncertainty of the extraction is much smaller than a present discrepancy between previous isotope shift measurements. We also discuss the theory uncertainty which enters the extraction of the 3He—4He isotope shift from the muonic measurements. Overview Fingerprint. Access to Document Annals of Physics , , In: Annals of Physics.
4He/3He laser microprobe analysis: a disruptive new technology for in-situ U-Th-He thermochronology
This site is using cookies to collect anonymous visitor statistics and enhance the user experience. Science Classification details. Abstract: Ernest Rutherford received the Nobel Prize for the discovery that radioactivity is a product of the spontaneous disintegration of a radioactive element the parent into another element the daughter. He soon realised that if the decay rate is known, this system can be used to determine the age of geological materials.
Publication Date: January Quartz Oscillator Study of Monolayer 4He and 3He – 4He Mixture Films Adsorbed on Solid H2 Kosterlitz-Thouless (KT) transitions were observed in submonolayer4He films with density greater than
Measured He ages ranged from 8 to 61 Ma, and were reproducible to better than a few percent despite very large variations in [U] and [Th]. In all samples with internal stratigraphy or independent age constraints, the He ages honored the expected relationships. These data demonstrate that internally consistent He ages can be obtained on goethite, but do not prove quantitative 4He retention. To assess possible diffusive He loss, stepped-heating experiments were performed on two goethite samples that were subjected to proton irradiation to produce a homogeneous distribution of spallogenic 3He.
The 3He release pattern indicates the presence of at least two diffusion domains, one with high helium retentivity and the other with very low retentivity at Earth surface conditions. Diffusive loss of 3He from the high retentivity domain is independent of the macroscopic dimensions of the analyzed polycrystalline aggregate, so probably represents diffusion from individual micrometer-size goethite crystals. This degree of retentivity is in excellent agreement with that independently predicted from the helium diffusion coefficients extrapolated to Earth surface temperature and held for the appropriate duration.
Weathering Geochronology by (U-Th)/He Dating of Geothite
The method is now in common use to study problems ranging from dating of Quaternary volcanic rocks, to establishing the timing and magnitude of fault motions, to documenting paleotopography. These applications have relied on measurement of the bulk age of the dated grain. The age spectrum carries unique quantitative information on the sample’s cooling path that complements the bulk age.
Numerical models will be developed to interpret profiles and to evaluate recognized potential pitfalls with the method.
Accurate determination of the absolute 3He/4He ratio of a synthesized helium standard of helium isotopes, such as tritium-3He dating, surface-exposure.
Kuerten , C. Castelijns, A. Waele, de , H. N2 – We calculated the thermodynamic quantities of dilute liquid 3He-4He mixtures, starting from experimental values of the specific heat and the osmotic pressure. Some results are especially useful for dilution refrigeration. Contrary to the calculations previously performed by Radebaugh, our results are in good agreement with the experimental date on both the osmotic pressure and the osmotic enthalpy. AB – We calculated the thermodynamic quantities of dilute liquid 3He-4He mixtures, starting from experimental values of the specific heat and the osmotic pressure.
Overview Fingerprint. Abstract We calculated the thermodynamic quantities of dilute liquid 3He-4He mixtures, starting from experimental values of the specific heat and the osmotic pressure. Access to Document Cryogenics , 25 8 , Kuerten, J. In: Cryogenics. Kuerten and C.
Weathering Geochronology by (U-Th)/He Dating of Geothite
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Keywords: groundwater, age dating, 4He, 14C, Baldwin County. Alabama. We attribute their high levels of 4He and 3He to an external flux of natural gas.
Bayanova, F. Mitrofanov, P. Serov, L. Nerovich, N. Yekimova, E. Nitkina and I. Geochronology – Methods and Case Studies. There are about 20 Palaeoproterozoic layered mafic-ultramafic bodies in Finland, most of which occur in a roughly east—west-trending, kmlong belt known as the Tornio-Na. The belt Fig. It includes more than ten isolated layered mafic-ultramafic bodies that are mostly ore-bearing Mitrofanov et al. The western and eastern arms of the triple junction are composed of large anorthosite-troctolite Main Ridge, Pyrshin, Kolvitsa intrusions Fig.
DE3011186A1 – Hoch 3 he- hoch 4 he-kuehlmaschine – Google Patents
The properties of 3He-4He solutions are discussed. Views. CrossRef citations to date. 0. Altmetric. Original Articles. 3He-4He quantum solutions.
Author s : Stephen W. Parman corresponding author [1, 3]; Mark D. Kurz ; Stanley R. Hart ; Timothy L. Grove . However, models of helium isotope evolution depend critically on the chemical behaviour of helium during mantle melting. It is generally assumed that helium is strongly enriched in mantle melts relative to uranium and thorium, yet estimates of helium partitioning in mantle minerals have produced conflicting results [4, 5, 6]. Here we present experimental measurements of helium solubility in olivine at atmospheric pressure.
Handbook of Environmental Isotope Geochemistry pp Cite as. Helium abundance and isotope variations have widespread application in groundwater-related studies. This stems from the inert nature of this noble gas and the fact that its two isotopes — helium-3 and helium-4 — have distinct origins and vary widely in different terrestrial reservoirs.
A closed cycle 3He-4He dilution refrigerator insensitive to gravity. Author(s) Publication date: /09; DOI:
A refrigerator of the described kind is known from the article “Continuous cooling in the millikelvin range”, published in Philips Technical Review 36, , No. The superleak therein forms part of a fountain pump which furthermore comprises a second superleak, a heating element and a capillary. Superfluid 4He is extracted from the vaporization chamber and is supplied to the second mixing chamber by the fountain pump.
The superfluid lie – reaches the vaporization chamber again via the first mixing chamber. Stopping can be simply effected by setting a valve in the e gas supply of the machine which is at room temperature to the closed position. Due to the interruption of the flow of concen-trated e to the mixing chamber, the transport of heat to the mixing ehamber is reduced and the temperature therein deereases. As long as eoneentrated 3He is present in the mixing ehamber, the lower eooling temperature ean be main-tained.
A dilution refrigerator comprising two mixing ehambers whieh are arranged at different levels and whieh are intereonneeted via a narrow duct offers the advantage for single-shot experiments that a machine of this kind ean temporarily produee eooling temperatures which are even lower than those produced by the macIline comprising only a single mixing chamber.
As a result, a single-shot experiment can be performed at a lower temperature and usually for a longer period of time in the machine comprising two mixing chambers than in the machine comprising one mixing chamber. The cooling of the upper mixing chamber, how-ever, is a problem in the machine comprising two mixing chambers. A single-shot experiment can be started only after such a long waiting period, if it is to be prevented that part of the cold production available for the single-shot is used for the cooling of the upper mixing chamber.
The latter means a substantial reduction of the time during which the lowest cooling temperature for the single-shot experiment in the upper mixing chamber can be maintained.