Neutron interferometry instrumentation at MURR

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Abstract

During the last two decades more than 35 fundamental quantum interference experiments have been performed using the perfect-silicon-crystal neutron interferometer. About one-half of these experiments have been carried out at the University of Missouri Research Reactor Center (MURR). In this paper we describe in some detail the instrumentation and the neutron optics of the two neutron interferometry setups currently situated at this 10 MW reactor.

Section snippets

Introduction and historical background

Louis deBroglie's 1924 postulate, that associated with moving matter of momentum p there is a wave of wavelength [1]λ=h/p,has remained one of the great insights of modern physics. Although the deBroglie–Schrödinger waves are fundamentally different from electro–magnetic light waves, they share unique analogies. The reason that they both display an equivalent wide variety of diffraction and interference phenomena can be gleaned from the parallel mathematical development of the wave equations

Basic principles of neutron interferometry

An interferometer crystal is a monolithic device consisting of two, three or more perfect crystal blades cut from a large perfect Si-crystal ingot perpendicular to a set of strongly reflecting Bragg planes (typically 2 2 0). The schematic diagram in Fig. 1 shows the symmetric three-crystal LLL interferometer, where the LLL refers to the three Laue-transmission geometry Bragg reflecting crystals. Cutting the interferometer from a perfect single crystal ensures that the respective crystal lattice

The University of Missouri Research Reactor Center

At 10 MW of thermal power, the University of Missouri Research Reactor Center [43] (MURR) shown schematically in Fig. 7 is the largest research reactor based at a university in the world. It is a light water moderated and cooled reactor with a neutron flux trap at the center of the core. The reactor core is surrounded by a 100 mm annular beryllium reflector necessary to maintain criticality in the core. The reactor design provides for irradiation positions within the flux trap, as well as,

Beam port B interferometer station

The beam port B interferometer station was originally designed and installed in 1976–1977, and was the site of many of the significant original neutron interferometry experiments investigating concepts in fundamental physics, including, among others, the first measurement of the neutron Sagnac phase shift [23], the null Fizeau effect for neutrons [28] and the Aharonov–Casher effect [31]. It was also the site of all the measurements of the gravitational phase shift of the neutron 15, 16, 17, 18,

Beam port C interferometer station

The interferometry setup at beam port C shown in Fig. 17Fig. 18 was originally designed and assembled in the time period 1985–1986. Although the beam port C interferometer setup operates at a fixed wavelength λ=2.35 Å, which is set by the 2θB take-off angle (41 deg.) from the monochromator, it has proved extremely versatile. It is here that the Spectral Filtering [32], Scalar Aharonov–Bohm effect 36, 37, Separation of Geometric and Dynamical phases [40] and the time of flight and polarized

Conclusion

The neutron interferometer is a unique tool for the study of the quantum mechanical wave nature of neutrons on a macroscopic level. The neutron interferometer remains one of the most sensitive instruments used in scientific research, able to probe each of the four fundamental forces of nature at a quantum level. However, in essence, it remains an optical instrument, and so has developed along similar lines to its optical interference counterparts. This paper has described in detail the two

Acknowledgements

The success of the work described in this paper depended greatly upon the skilled workmanship of Clifford Holmes and his staff at the Missouri Physics Machine Shop. The contributions of Dr. Helmut Kaiser to this program over many years have been extremely significant. This work supported by the US NSF Physics Division, research grant # 9603559. KCL received additional support through the United States Department of Education. BEA would like to acknowledge support from an Australian Research

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