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Environmental Measurements in the Sedrun Access Shaft to the Gotthard Base Tunnel -- a Promising Site for a Long-Baseline Atom Interferometer

M. Guinchard, O. Buchmüller, S. Calatroni, J. Ellis, S. Hoell, M. Jaussi, L. Lombriser, M. Pentella, D. Thuliez, D. Valuch

Abstract

Atom interferometer (AI) experiments offer interesting prospects for searches for the interactions of ultralight bosonic dark matter with Standard Model particles as well as detection of gravitational waves in a frequency band inaccessible to experiments that are operating or under construction. Ideal locations for the next generation of such experiments are provided by long vertical shafts, such as that providing access to the Gotthard base railway tunnel from the Sedrun locality in the Canton Grisons of Switzerland. We present the results of an exploratory environmental measurement campaign at this location to evaluate the ground motion activity and the background electromagnetic field quality. We find that the backgrounds due to both ground motion and electromagnetic fields, including those due to passing trains, are low enough for successful operation of a 800-m AI experiment.

Environmental Measurements in the Sedrun Access Shaft to the Gotthard Base Tunnel -- a Promising Site for a Long-Baseline Atom Interferometer

Abstract

Atom interferometer (AI) experiments offer interesting prospects for searches for the interactions of ultralight bosonic dark matter with Standard Model particles as well as detection of gravitational waves in a frequency band inaccessible to experiments that are operating or under construction. Ideal locations for the next generation of such experiments are provided by long vertical shafts, such as that providing access to the Gotthard base railway tunnel from the Sedrun locality in the Canton Grisons of Switzerland. We present the results of an exploratory environmental measurement campaign at this location to evaluate the ground motion activity and the background electromagnetic field quality. We find that the backgrounds due to both ground motion and electromagnetic fields, including those due to passing trains, are low enough for successful operation of a 800-m AI experiment.
Paper Structure (14 sections, 57 figures, 1 table)

This paper contains 14 sections, 57 figures, 1 table.

Table of Contents

  1. Introduction
  2. The Sedrun Multi-Function Site of the Gotthard Base Tunnel
  3. Physics motivations
  4. Environmental Requirements for an Atomic Interferometer
  5. Vibration and seismic noise requirements
  6. Electromagnetic noise requirements
  7. Modus Operandi for the Environmental Measurement Campaign
  8. Vibration and seismic noise measurements
  9. Electromagnetic noise measurements
  10. Experimental Results
  11. Vibration and seismic noise results
  12. Electromagnetic noise results
  13. Conclusions
  14. Acknowledgements

Figures (57)

  • Figure 1: Sketch of a North-South section through the Swiss Alps, illustrating the twin-bore Gotthard Base Tunnel together with its access tunnels and shafts. Adapted from Cooper:2005.
  • Figure 2: Diagram of the Sedrun Multi-Function Site (MFS) of the Gotthard Base Tunnel, illustrating the horizontal access gallery and the two vertical access shafts FABBRI2019379.
  • Figure 3: Space-time diagram of a pair of cold-atom interferometers based on single-photon transitions between the ground state (blue) and the excited state (red dashed). Height is shown on the vertical axis and the time axis is horizontal. The laser pulses (wavy lines) travelling across the baseline from opposite ends divide, redirect, and recombine the atomic de Broglie waves, yielding interference patterns that are sensitive to the modulation of the atomic transition frequency caused by coupling to ULDM, or the space-time distortions caused by GWs.
  • Figure 4: Conceptual scheme of an Atom Interferometer (AI) experiment with two atom sources that project clouds vertically and are manipulated by a single laser beam (this diagram is not to scale) Buchmueller:2023nll.
  • Figure 5: The RMS spectral density of surface vertical displacement measurements at CERN Arduini:2023wce, compared with the New High and Low Noise Models (NHNM and NLNM) peterson1993observations. The shaded band corresponds to the difference between the minimum and maximum daily measurements.
  • ...and 52 more figures