Using a cw 465 nm Laser to Probe Metastable He2 Molecules

Tastevin, Geneviève; Głowacz, B.; Nacher, Pierre-Jean

doi:10.1007/s10909-009-0050-5

Cited by 3 publications

References 41 publications

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Optical Hyperpolarization of Noble Gases for Medical Imaging

Pałasz¹,

Tomanek²

2016

Gas Phase NMR

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Magnetic resonance imaging (MRI) of human or animal lungs became possible with the application of hyperpolarized noble gases, such as 3He or 129Xe. This method allows obtaining information on lung morphology and functionality. Introduction of hyperpolarized noble gases provided as well a new tool for non-medical applications such as neutron filters or nuclear magnetic resonance (NMR) spectroscopy studies in porous materials. The high polarization of noble gases is possible using so-called optical pumping methods. In this chapter the two most common polarization techniques of noble gases (3He and 129Xe), spin exchange optical pumping (SEOP) and metastability exchange optical pumping (MEOP) are presented. Variations of these methods delivering higher 3He and 129Xe polarization including hybrid SEOP or MEOP in standard conditions and in elevated pressure and high magnetic fields are also reported. A short description of the equipment used for gas polarization is also provided.

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Optical Hyperpolarization of Noble Gases for Medical Imaging

Pałasz¹,

Tomanek²

2016

Gas Phase NMR

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An experimental setup for creating and imaging 4He2* excimer cluster tracers in superfluid helium-4 via neutron-3He absorption reaction

Sonnenschein

Tsuji

Kokuryu

et al. 2020

Review of Scientific Instruments

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For the purpose of future visualization of the flow field in superfluid helium-4, clusters of the triplet state excimer 4He2* are generated along the micro-scale recoil tracks of the neutron-absorption reaction n + 3He → 3T + p. This reaction is induced by neutron irradiation of the 3He fraction contained in natural isotopic abundance liquid helium with neutron beams either from the Japan Proton Accelerator Research Complex, Materials and Life Science Experimental Facility (JPARC)/Materials and Life Science Experimental Facility or from the Kyoto University Institute for Integrated Radiation and Nuclear Science. These 4He2* clusters are expected to be ideal tracers of the normal-fluid component in superfluid helium with several advantageous properties. Evidence of the excimer generation is inferred by detection of laser induced fluorescence emitted from the 4He2* clusters excited by a purpose-built short pulse gain-switched titanium:sapphire (Ti:sa) laser operating at a wavelength of 905 nm. The setup and performance characteristics of the laser system including the Ti:sa and two continuous wave re-pumping lasers are described. Detection at the fluorescence wavelength of 640 nm is performed by using optical bandpass filtered photomultiplier tubes (PMT). Electrical noise in the PMT acquisition traces could successfully be suppressed by post-processing with a simple algorithm. Despite other laser-related backgrounds, the excimer was clearly identified by its fluorescence decay characteristics. Production of the excimer was found to be proportional to the neutron flux, adjusted via insertion of different collimators into the neutron beam. These observations suggest that the apparatus we constructed does function in the expected manner and, therefore, has the potential for groundbreaking turbulence research with superfluid helium.

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