Neutron interferometry as a dark matter detector

Abstract

We analyze the possibility of detecting the existence of mirror matter, a possible component of dark matter, through neutron interferometry. We develop an interferometer using bandpass multilayers in reflection and transmission geometry and discuss its advantages and limitations. We demonstrate that our setup can probe a considerable range of neutron-mirror neutron mixing parameters allowing us to show the existence of mirror matter using present day neutron sources based on fission or spallation processes.

Figures (9)

• Figure 1: Scheme of the neutron interferometer, with path I (red arrows) and path II (violet arrows). The regions in green are magnetically shielded against disturbing external fields by mu-metal. The incident polarized beam is split by the beam splitter BS in two beams and after their respective reflection from mirrors C$_{\rm I}$ and C$_{\rm II}$ recombined in the recombination mirror REC. The transmitted and reflected beam thereof are measured with detectors O and H. By rotating the phase shifter PS about the vertical axis and adjusting the amplitude of the magnetic field $\vec{\bf B}_{II}$, the phase of the neutrons along path II can be varied. For more details see the text.
• Figure 2: Plots of the intensity $I_O$ as a function of $\epsilon_{nn'}\in [10^{-10}, 10^{-9}]\;\mathrm{eV}$ for fixed values of $\delta m$. Red line: case without mixing, blue dotted line: $\delta m=0.5\cdot 10^{-8} \;\mathrm{eV}$ , and black line: $\delta m= 10^{-8} \;\mathrm{eV}$. The insets show $I_O$ as a function of $\delta m\in [6\cdot10^{-9}, 10^{-8}]\;\mathrm{eV}$, for constant values of $\epsilon_{n n'}$; red line: $\epsilon_{n n'}= 0 \;\mathrm{eV}$ (case without mixing), blue dotted line: $\epsilon_{n n'}= 0.5\cdot 10^{-9} \;\mathrm{eV}$, and black line: $\epsilon_{n n'}= 10^{-9} \;\mathrm{eV}$.
• Figure 3: Contour plots of the interference intensity $I_O^{INT}$ as a function of $\epsilon_{n n'}\in [10^{-10}, 10^{-9}]\;\mathrm{eV}$ and $\delta m\in [3.5\cdot10^{-9}, 10^{-8}]\;\mathrm{eV}$.
• Figure 4: Difference intensity $I_H - I_O$ as a function of $\epsilon_{n n'}\in [10^{-10}, 10^{-9}]\;\mathrm{eV}$ for fixed values of $\delta m$. Red line: case without mixing, blue dotted line: $\delta m= 0.5\cdot10^{-8} \;\mathrm{eV}$ and black line: $\delta m= 10^{-8} \;\mathrm{eV}$. The inset shows $I_H - I_O$ as a function of $\delta m\in [10^{-9}, 10^{-8}]\;\mathrm{eV}$ for constant $\epsilon_{n n'}$. The red, blue dotted, and the black lines indicate the results for $\epsilon_{n n'}= 0 \;\mathrm{eV}$, $\epsilon_{n n'}=0.5 \cdot 10^{-9} \;\mathrm{eV}$, and $\epsilon_{n n'}= 10^{-9} \;\mathrm{eV}$, respectively.
• Figure 5: Main graph: plot of the intensity $I_O$ as a function of $\epsilon_{nn'}\in [10^{-10}, 10^{-9}]\;\mathrm{eV}$ for fixed values of $\delta m=10^{-8} \;\mathrm{eV}$ and different values of $D_{eff}$. Inset: plot of $I_O$ as a function of $\delta m\in [10^{-9}, 10^{-8}]\;\mathrm{eV}$, for constant values of $\epsilon_{n n'}=10^{-9} \;\mathrm{eV}$ and the same $D_{eff}$ values used in the main plot.