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Rate amplification of the two photon emission from para-hydrogen toward the neutrino mass measurement

Takahiko Masuda, Hideaki Hara, Yuki Miyamoto, Susumu Kuma, I. Nakano, Chiaki Ohae, N. Sasao, Minoru Tanaka, Satoshi Uetake, A. Yoshimi, K. Yoshimura, M. Yoshimura

Published Apr 23, 2015• 0 citations
Publisher
DOI
10.1007/978-3-319-61588-2_9

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We discuss a possibility of detecting a coherent photon pair emission and related radiative neutrino pair emission from excited atoms. It is shown that atoms of lambda- and ladder-type three level system placed in a pencil-like cylinder give a back to back emission of two photons of equal energy Δ/2Δ/2Δ/2, sharply peaked with a width $\propto $ 1/(target size) and well collimated along the cylinder axis. This process has a measurable rate ∝\propto∝ (target number density) 2×^2 \times2× target volume, while a broader spectral feature of one-photon distribution separated by (mass sum of a neutrino pair)2/(2Δ)^2/(2Δ)2/(2Δ) from the two photon peak may arise from radiative neutrino pair emission, with a much smaller rate.
In this paper, we describe an experiment which was conducted to explore the macro-coherent amplification mechanism using a two-photon emission process from the first vibrationally-excited state of para-hydrogen molecule. Large coherence in the initial state was prepared by the adiabatic Raman population transfer method, and the lowest Stokes sideband was used as a trigger field. We observed the coherent two-photon emission consistent with the expectation of the paired super-radiance master equation.