Probing Dark Energy models with neutrons

There is a deep connection between cosmology -- the science of the infinitely large --and particle physics -- the science of the infinitely small. This connection is particularly manifest in neutron particle physics. Basic properties of the neutron -- its Electric Dipole Moment and its lifetime -- are intertwined with baryogenesis and nucleosynthesis in the early Universe. I will cover this topic in the first part, that will also serve as an introduction (or rather a quick recap) of neutron physics and Big Bang cosmology. Then, the rest of the manuscript will be devoted to a new idea: using neutrons to probe models of Dark Energy. In the second part, I will present the chameleon theory: a light scalar field accounting for the late accelerated expansion of the Universe, which interacts with matter in such a way that it does not mediate a fifth force between macroscopic bodies. However, neutrons can alleviate the chameleon mechanism and reveal the presence of the scalar field with properly designed experiments. In the third part, I will describe a recent experiment performed with a neutron interferometer at the Institut Laue Langevin that sets already interesting constraints on the chameleon theory. Last, the chameleon field can be probed by measuring the quantum states of neutrons bouncing over a mirror. In the fourth part I will present the status and prospects of the GRANIT experiment at the ILL

Limits on the Axial Coupling Constant of New Light Bosons

We report on a neutron particle physics experiment, which provides for the first time an upper limit on the strength of an axial coupling constant for a new light spin 1 boson in the millimeter range. Such a new boson would mediate a new force between ordinary fermions, like neutrons and protons. The experiment was set up at the cold neutron reflectometer Narziss at the Paul Scherrer Institute and uses Ramsey's technique of separated oscillating fields to search for a pseudomagnetic neutron spin precession induced by this new interaction. For the axial coupling constant $g_A^2$, an upper limit of $6\times10^{-13}$ (95% C.L.) was determined for an interaction range of 1 mm

Comments on "Limits on possible new nucleon monopole-dipole interactions from the spin relaxation rate of polarized 3^3He gas"

In the article "Limits on possible new nucleon monopole-dipole interactions from the spin relaxation rate of polarized $^3$He gas", new limits on short-range, Axion-like interactions are presented. In this comment it is shown that the theoretical treatement of the data overestimates the sensitivity of the proposed method. We provide the corrected limits

A proposed search for new light bosons using a table-top neutron Ramsey apparatus

If a new light boson existed, it would mediate a new force between ordinary fermions, like neutrons. In general such a new force is described by the Compton wavelength $\lambda_c$ of the associated boson and a set of dimensionless coupling constants. For light boson masses of about $10^-4$ eV, $\lambda_c$ is of the order millimeters. Here, we propose a table-top particle physics experiment which provides the possibility to set limits on the strength of the coupling constants of light bosons with spin-velocity coupling. It utilises Ramsey's technique of separated oscillating fields to measure the pseudo-magnetic effect on neutron spins passing by a massive sample.Comment: proceedings of the ECNS 2011 conference, published in Jour of Phys. Conf. Serie

Experimental constraints for additional short-range forces from neutron experiments

We present preliminary results on sensitivity of experiments with slow neutrons to constrain additional forces in a wide distance range: from picometers to micrometers. In the sub-nanometer range, available data on lengths of neutron scattering at nuclei provide the most competitive constraint. We show that it can be improved significantly in a dedicated measurement of asymmetry of neutron scattering at noble gases. In the micrometer range, we present sensitivity of the future GRANIT experiment. Further analysis will be presented in following publications.Comment: presented in "les rencontres de Moriond" 2007 conferenc

Frequency shifts and relaxation rates for spin 1/2 particles moving in electromagnetic fields

We discuss the behaviour of the Larmor frequency shift and the longitudinal relaxation rate due to non-uniform electromagnetic fields on an assembly of spin 1/2 particles, in adiabatic and nonadiabatic regimes. We also show some general relations between the various frequency shifts and between the frequency shifts and relaxation rates. The remarkable feature of all our results is that they were obtained without any specific assumptions on the explicit form of the correlation functions of the fields. Hence, we expect that our results are valid both for diffusive and ballistic regime of motion and arbitrary cell shapes and surface scattering. These results can then be applied to a wide variety of realistic systems

Constraining short-range spin-dependent forces with polarized helium 3 at the Laue-Langevin Institute

We have searched for a short-range spin-dependent interaction mediated by a hypothetical light scalar boson with CP-violating couplings to the neutron using the spin relaxation of hyperpolarized $^3$He. The walls of the $^3$He cell would generate a depolarizing pseudomagnetic field.Comment: Twelfth Conference on the Intersections of Particle and Nuclear Physics (CIPANP2015), Vail Marriott Mountain Resort, Vail, Colorado, US

Spontaneous emission of graviton by a quantum bouncer

Spontaneous emission of graviton rates for the quantum bouncer states are evaluated

Gravitational resonance spectroscopy with an oscillating magnetic field gradient in the GRANIT flow through arrangement

Gravitational resonance spectroscopy consists in measuring the energy spectrum of bouncing ultracold neutrons above a mirror by inducing resonant transitions between different discrete quantum levels. We discuss how to induce the resonances with a flow through arrangement in the GRANIT spectrometer, excited by an oscillating magnetic field gradient. The spectroscopy could be realized in two distinct modes (so called DC and AC) using the same device to produce the magnetic excitation. We present calculations demonstrating the feasibility of the newly proposed AC mode