Muonium Emission into Vacuum from Mesoporous Thin Films at Cryogenic Temperatures

A. Antognini, P. Crivelli, T. Prokscha, K. S. Khaw, B. Barbiellini, L. Liszkay, K. Kirch, K. Kwuida, E. Morenzoni, F. M. Piegsa, Z. Salman, and A. Suter
Phys. Rev. Lett. 108, 143401 – Published 3 April 2012

Abstract

We report on muonium (Mu) emission into vacuum following μ+ implantation in mesoporous thin SiO2 films. We obtain a yield of Mu into vacuum of (38±4)% at 250 K and (20±4)% at 100 K for 5 keV μ+ implantation energy. From the implantation energy dependence of the Mu vacuum yield we determine the Mu diffusion constants in these films: DMu250K=(1.6±0.1)×104cm2/s and DMu100K=(4.2±0.5)×105cm2/s. Describing the diffusion process as quantum mechanical tunneling from pore to pore, we reproduce the measured temperature dependence T3/2 of the diffusion constant. We extract a potential barrier of (0.3±0.1)eV which is consistent with our computed Mu work function in SiO2 of [0.3,0.9]eV. The high Mu vacuum yield, even at low temperatures, represents an important step toward next generation Mu spectroscopy experiments.

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  • Received 23 December 2011

DOI:https://doi.org/10.1103/PhysRevLett.108.143401

© 2012 American Physical Society

Authors & Affiliations

A. Antognini1,*, P. Crivelli1,†, T. Prokscha2,‡, K. S. Khaw1, B. Barbiellini3, L. Liszkay4, K. Kirch1,2, K. Kwuida1, E. Morenzoni2, F. M. Piegsa1, Z. Salman2, and A. Suter2

  • 1Institute for Particle Physics, ETH Zurich, Switzerland
  • 2Paul Scherrer Institute, Villigen, Switzerland
  • 3Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
  • 4CEA, Irfu, Sédi, Centre de Saclay, F-91191 Gif-sur-Yvette, France

  • *aldo@phys.ethz.ch
  • crivelli@phys.ethz.ch
  • thomas.prokscha@psi.ch

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Issue

Vol. 108, Iss. 14 — 6 April 2012

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