Experiments with Gravitationally-bound Ultracold Neutrons at the European Spallation Source ESS

AbstractExperiments with gravitationally-bound ultracold neutrons have made substantial progress in the last decade. They have been contributing to answer scientific questions ranging from gravity tests at micron distances, the direct search for dark matter particles as axions, and dark energy realizations. Comparing the present accuracy of around 10-14 eV - achieved with a gravity resonance spectroscopy technique - with the by many orders of magnitude expected smaller size of inevitable systematic errors, one may conclude that the present experiments are heavily restricted by the limited strength of today's ultracold neutron (UCN) sources.We propose to build a dedicated UCN source at the European Spallation Source in order to perform experiments with gravitationally-bound UCN

Gravity Resonance Spectroscopy and Einstein-Cartan Gravity

The qBounce experiment offers a new way of looking at gravitation based on quantum interference. An ultracold neutron is reflected in well-defined quantum states in the gravity potential of the Earth by a mirror, which allows to apply the concept of gravity resonance spectroscopy (GRS). This experiment with neutrons gives access to all gravity parameters as the dependences on distance, mass, curvature, energy-momentum as well as on torsion. Here, we concentrate on torsion.Comment: Contributed to the 11th Patras Workshop on Axions, WIMPs and WISPs, Zaragoza, June 22 to 26, 2015, 6 pages, 4 figure

Spectroscopy with cold and ultra-cold neutrons

We present two new types of spectroscopy methods for cold and ultra-cold neutrons. The first method, which uses the \RB drift effect to disperse charged particles in a uniformly curved magnetic field, allows to study neutron $\beta$-decay. We aim for a precision on the 10$^{-4}$ level. The second method that we refer to as gravity resonance spectroscopy (GRS) allows to test Newton's gravity law at short distances. At the level of precision we are able to provide constraints on any possible gravity-like interaction. In particular, limits on dark energy chameleon fields are improved by several orders of magnitude.Comment: 3 pages, 2 figures, Proceedings of the Fifteenth International Symposium on Capture Gamma-Ray Spectroscopy and Related Topics (CGS15), TU Dresden, August 25 to August 29, 201

Rapid Internalization of the Oncogenic K+ Channel KV10.1

KV10.1 is a mammalian brain voltage-gated potassium channel whose ectopic expression outside of the brain has been proven relevant for tumor biology. Promotion of cancer cell proliferation by KV10.1 depends largely on ion flow, but some oncogenic properties remain in the absence of ion permeation. Additionally, KV10.1 surface populations are small compared to large intracellular pools. Control of protein turnover within cells is key to both cellular plasticity and homeostasis, and therefore we set out to analyze how endocytic trafficking participates in controlling KV10.1 intracellular distribution and life cycle. To follow plasma membrane KV10.1 selectively, we generated a modified channel of displaying an extracellular affinity tag for surface labeling by α-bungarotoxin. This modification only minimally affected KV10.1 electrophysiological properties. Using a combination of microscopy and biochemistry techniques, we show that KV10.1 is constitutively internalized involving at least two distinct pathways of endocytosis and mainly sorted to lysosomes. This occurs at a relatively fast rate. Simultaneously, recycling seems to contribute to maintain basal KV10.1 surface levels. Brief KV10.1 surface half-life and rapid lysosomal targeting is a relevant factor to be taken into account for potential drug delivery and targeting strategies directed against KV10.1 on tumor cells

The neutron and its role in cosmology and particle physics

Experiments with cold and ultracold neutrons have reached a level of precision such that problems far beyond the scale of the present Standard Model of particle physics become accessible to experimental investigation. Due to the close links between particle physics and cosmology, these studies also permit a deep look into the very first instances of our universe. First addressed in this article, both in theory and experiment, is the problem of baryogenesis ... The question how baryogenesis could have happened is open to experimental tests, and it turns out that this problem can be curbed by the very stringent limits on an electric dipole moment of the neutron, a quantity that also has deep implications for particle physics. Then we discuss the recent spectacular observation of neutron quantization in the earth's gravitational field and of resonance transitions between such gravitational energy states. These measurements, together with new evaluations of neutron scattering data, set new constraints on deviations from Newton's gravitational law at the picometer scale. Such deviations are predicted in modern theories with extra-dimensions that propose unification of the Planck scale with the scale of the Standard Model ... Another main topic is the weak-interaction parameters in various fields of physics and astrophysics that must all be derived from measured neutron decay data. Up to now, about 10 different neutron decay observables have been measured, much more than needed in the electroweak Standard Model. This allows various precise tests for new physics beyond the Standard Model, competing with or surpassing similar tests at high-energy. The review ends with a discussion of neutron and nuclear data required in the synthesis of the elements during the "first three minutes" and later on in stellar nucleosynthesis.Comment: 91 pages, 30 figures, accepted by Reviews of Modern Physic

qBounce - from the quantum bouncer to gravity resonance spectroscopy

Abweichender Titel laut Übersetzung der Verfasserin/des VerfassersZsfassung in engl. SpracheIm Rahmen dieser Arbeit wurde das Spektrometer qBounce entwickelt, mit dessen Hilfe die Dynamik quantenmechanischer Wellenpakete im Gravitationsfeld der Erde studiert und erstmalig eine Resonanzmethode zur Untersuchung der Gravitation realisiert wurde. Die dazu verwendeten ultrakalten Neutronen bilden im Gravitationspotential der Erde quantenmechanische Zustände mit diskreten, nicht-äquidistanten Eigenenergien im Picoelektronenvolt-Bereich. Die Experimente erlauben die Überprüfung des Newton'schen Gravitationsgesetzes bei kleinen Abständen mit den hochpräzisen Messmethoden der Quantenmechanik. Die Messungen wurden in mehreren Experimentierzeiten am Institut Laue-Langevin in Grenoble, Frankreich durchgeführt.Der erste Teil der Dissertation beschreibt die erste experimentelle Untersuchung des Quantum Bouncers mit Neutronen. Als Quantum Bouncer wird ein quantenmechanisches Teilchen im Gravitationspotential bezeichnet, welches sich zeitlich entwickelt. Nach einer Darstellung des Messprinzips und der mathematischen Beschreibung wird auf die technische Realisierung der Experimente eingegangen. Einen großen Stellenwert nimmt hierbei die Weiterentwicklung hochauflösender Spurdetektoren sowie die Entwicklung eines automatisierten Ausleseverfahrens ein. Der Beschreibung der Messungen folgt eine ausführliche Analyse und Diskussion der gewonnenen Daten.Im zweiten Teil der Dissertation wird die experimentelle Umsetzung einer resonanzspektroskopischen Methode in Verbindung mit dem Quantum Bouncer beschrieben. Diese stellt die erstmalige Realisierung einer Resonanzmethode zur Untersuchung der Gravitation dar. Nach einer Vorstellung verschiedener experimenteller Konzepte folgt eine mathematische Beschreibung der Anregung der Übergänge. Bei der sich anschließenden Erläuterung der technischen Umsetzung ist die Erzeugung kontrollierbarer und reproduzierbarer Vibrationen der verwendeten Neutronenspiegel besonders hervorzuheben. In mehreren durchgeführten Experimenten wurden alle möglichen Übergänge zwischen den ersten drei Eigenzuständen der gravitativ gebundenen Neutronen nachgewiesen. Diese Messungen werden ausführlich analysiert und diskutiert. Im letzten Abschnitt werden aus den Messungen neue experimentelle Grenzen auf hypothetische spinabhängige kurzreichweitige Wechselwirkungen abgeleitet. Diese verbessern die einzigen im Mikrometerbereich gemessenen Grenzen im Reichweitenbereich von 5 µm bis 50 µm um einen Faktor zwischen 14 und 149.In the scope of this thesis, the spectrometer qBounce was developed to study the time evolution of a quantum particle in the gravitational field of the Earth and to realise a resonance method to explore gravity. As test particles, ultra-cold neutrons were used. They form bound states in the gravity potential with discrete, non-equidistant eigenenergies in the range of peV. Therefore, the experiments allow for testing of Newton's Inverse Square Law at short distances with the precise measuring techniques of quantum mechanics.The measurements were performed at the Institut Laue-Langevin in Grenoble, France.The first part of this thesis describes the first experimental investigation of the Quantum Bouncer with neutrons. A Quantum Bouncer is a quantum particle in the gravity field, which evolves in time. After describing the principles of both measurement and the underlying mathematics, technical details on the realisation of the experiment are elaborated. At this point, the further development of track detectors with a spatial resolution of about two microns and the development of an automated readout process play a significant role. The description of the measurement is followed by a detailed data analysis and discussion.The second part of the thesis deals with the experimental realisation of a resonance spectroscopy method linked with the Quantum Bouncer, which can also be regarded as the first realisation of such a method in order to explore gravity. Furthermore, the realised excitation of the gravitationally bound quantum states by means of mechanical vibrations results in the first resonance method that may not be described by electromagnetism. The presentation of different possible experimental designs is followed by a mathematical description of vibrationally induced transitions of quantum states of neutrons in the Earth's gravitational field. Technical details of the set-up are provided, with the main focus being on the generation of controllable and reproducible vibrations of the used neutron mirrors. In various experiments, all possible transitions between the first three eigenstates of the gravitationally bound neutrons were substantiated. These measurements are analysed and discussed in full detail. In the last part, these measurements are used to set new experimental limits for the existence of hypothetical short-ranged spin-dependant interactions. The only existing limits measured in the micron range are constrained in a range from 5 µm to 50 µm by a factor of 14 to 149.9

Multifold paths of neutrons in the three-beam interferometer detected by a tiny energy kick

A neutron optical experiment is presented to investigate the paths taken by neutrons in a three-beam interferometer. In various beam paths of the interferometer, the energy of the neutrons is partially shifted so that the faint traces are left along the beam path. By ascertaining an operational meaning to "the particle's path," which-path information is extracted from these faint traces with minimal perturbations. Theory is derived by simply following the time evolution of the wave function of the neutrons, which clarifies the observation in the framework of standard quantum mechanics. Which-way information is derived from the intensity, sinusoidally oscillating in time at different frequencies, which is considered to result from the interfering cross terms between stationary main component and the energy-shifted which-way signals. Final results give experimental evidence that the (partial) wave functions of the neutrons in each beam path are superimposed and present in multiple locations in the interferometer

Happy birthday, ultra-cold neutron!∗

What is driving the accelerated expansion of the universe and do we have an alternative for Einstein's cosmological constant? What is dark matter made of? Do extra dimensions of space and time exist? Is there a preferred frame in the universe? To which extent is left-handedness a preferred symmetry in nature? What's the origin of the baryon asymmetry in the universe? These fundamental and open questions are addressed by precision experiments using ultra-cold neutrons. This year, we celebrate the 50th anniversary of their first production, followed by first pioneering experiments. Actually, ultra-cold neutrons were discovered twice in the same year – once in the eastern and once in the western world [1, 2]. For five decades now research projects with ultra-cold neutrons have contributed to the determination of the force constants of nature's fundamental interactions, and several technological breakthroughs in precision allow to address the open questions by putting them to experimental test. To mark the event and tribute to this fabulous object, we present a birthday song for ultra-cold neutrons with acoustic resonant transitions [3], which are based solely on properties of ultra-cold neutrons, the inertial and gravitational mass of the neutron m, Planck's constant h, and the local gravity g. We make use of a musical intonation system that bears no relation to basic notation and basic musical theory as applied and used elsewhere [4] but addresses two fundamental problems of music theory, the problem of reference for the concert pitch and the problem of intonation