Imaging Fluorescence of He_{2}^{*} Excimers Created by Neutron Capture in Liquid Helium II

X Wen; S R Bao; L McDonald; J Pierce; G L Greene; Lowell Crow; Xin Tong; A Mezzacappa; R Glasby; W Guo; M R Fitzsimmons

doi:10.1103/PhysRevLett.124.134502

Imaging Fluorescence of He_{2}^{*} Excimers Created by Neutron Capture in Liquid Helium II

Phys Rev Lett. 2020 Apr 3;124(13):134502. doi: 10.1103/PhysRevLett.124.134502.

Authors

X Wen^{1

2

3}, S R Bao^{4

5}, L McDonald^{1

6}, J Pierce², G L Greene^{1

2}, Lowell Crow², Xin Tong^{2

7

8}, A Mezzacappa^{1

2

9}, R Glasby^{6

9}, W Guo^{4

5}, M R Fitzsimmons^{1

2

3}

Affiliations

¹ Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA.
² Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
³ Shull Wollan Center-A Joint Institute for Neutron Sciences, Oak Ridge, Tennessee 37830, USA.
⁴ Mechanical Engineering Department, Florida State University, Tallahassee, Florida 32310, USA.
⁵ National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA.
⁶ Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
⁷ Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing 100049, China.
⁸ Spallation Neutron Source Science Center, Dongguan 523803, China.
⁹ Joint Institute for Computational Sciences, Oak Ridge, Tennessee 37830, USA.

PMID: 32302187
DOI: 10.1103/PhysRevLett.124.134502

Abstract

We show unequivocal evidence for formation of He_{2}^{*} excimers in liquid He II created by ionizing radiation produced through neutron capture. Laser beams induce fluorescence of the excimers. The fluorescence is recorded at a rate of 55.6 Hz by a camera. The location of the fluorescence is determined with an uncertainty of 5 μm. The technique provides an opportunity to record the flow of He_{2}^{*} excimers in a medium with very small viscosity and enables measurement of turbulence around macroscopic liter size objects or vortex matter in three dimensions.