Technical Papers and Presentations

Noble gasses such as argon and helium are utilized within In Gas Laser Ionization and Spectroscopy (IGLIS) [1] and Ion Guide Isotope Separation On-Line (IGISOL) [2] techniques to thermalize and transport the nuclear reactions products, which often have short lifetimes and small production yields. Experimental studies of nuclei properties provide essential information to validate theoretical nuclear models and to increase their predictive power. To facilitate these studies, thorough understanding and characterization of utilized gas flows are essential. Characterization was performed both experimentally at IGLIS and IGISOL facilities and numerically using the Computational Fluid Dynamics (CFD) Module of COMSOL Multiphysics^®. 

With the in-gas-jet method, an extension of the IGLIS technique, the spectral resolution is improved by more than one order of magnitude in comparison to in-gas-cell ionization spectroscopy [3], while maintaining a high efficiency. This allows determination of nuclei properties with higher precision. The flow parameters of such supersonic gas jets were characterized at the IGLIS laboratory at KU Leuven using Planar Laser Induced Fluorescence (PLIF). Moreover, the numerical calculations were performed to obtain temperature, velocity and Mach number profiles of supersonic jets formed by a de Laval nozzle. The calculations were performed using the High Mach Number Flow interface from the CFD Module which is part of COMSOL Multiphysics^®. The experimental and numerical results fairly agreed for a range of coordinates after the nozzle’s exit [4].

Additionally, extraction efficiencies and timings of subsonic helium and argon flows were recently measured at the IGISOL laboratory at University of Jyvaskyla. This characterization defines lower limits of production yields and lifetimes of the nuclear reaction products, which are still accessible for studies with the In Gas methods. The numerical calculations were performed using the Laminar Flow and Transport of Diluted Species interfaces.

[1] Yu. Kudryavtsev et al., Beams of short lived nuclei produced by selective laser ionization in a gas cell, Nucl. Instrum. Meth. Phys. Res. B, 114, 350 (1996)
[2] I. D. Moore, P. Dendooven, and J. Ärje, The IGISOL technique—three decades of developments. In: Äystö J., Eronen T., Jokinen A., Kankainen A., Moore I.D., Penttilä H., Three decades of research using IGISOL technique at the University of Jyväskylä. Springer, Dordrecht (2013)

[3] R. Ferrer et al., Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion, Nat. Commun. 8, 14520 (2017)
[4] A. Zadvornaya et al., Characterization of Supersonic Gas Jets for High Resolution Laser Ionization Spectroscopy of Heavy Elements, Phys. Rev. X, 8 (2018)