The neutron as a tool and the neutron

The neutron as a tool, and the neutron as an object Dirk Dubbers U. Heidelberg 22. 05. 2019 The neutron as a tool, and the neutron as an object 1

Weightwatcher: A. The neutron as a tool: 40 kg of protons 32 kg of neutrons 22 g of electrons Neutron scattering (from a frog's perspective) B. The neutron as an object: ~ as a wave ~ as a particle 22. 05. 2019 The neutron as a tool, and the neutron as an object 2

A. The neutron as a tool Some trivia on neutron scattering A look into the interior of matter: 22. 05. 2019 The neutron as a tool, and the neutron as an object 3

Let us dream: We place a camera onto some site r 0 and take a snapshot of its surrounding: ρ(r − r 0) = ρ(x) r x r 0 x = r − r 0 22. 05. 2019 The neutron as a tool, and the neutron as an object 4

Advanced dream: Take a video of the molecules: ρ(x, t) Nowadays one stores movies in the Frequency Domain. Examples: 1. The storage of a piece of music f(t) in an mp 3 player: FFT f(t) ─────> g(ω) = ∫ f(t) e−iωt dω (Bandwidth and time resolution: Δω·Δt ~ 1) 22. 05. 2019 The neutron as a tool, and the neutron as an object 5

2. The storage of a snapshot ρ(x) in the cloud: FFT ρ(x) ─────> S(q) = ∫ ρ(x) e−iq·x dq y qy x qx (Range of wavevectors Δq, spatial resolution Δx : Δq·Δx ~ 1) 22. 05. 2019 The neutron as a tool, and the neutron as an object 6

3. The storage of a video ρ(x, t) as S(q, ω): Replay: FFT − 1 S(q, ω) ─────> ρ(x, t) = ∫∫ S(q, ω) ei(q·x−ωt) dx dt 22. 05. 2019 The neutron as a tool, and the neutron as an object 7

Neutrons fulfill this dream! They provide the atomic scattering function S(q, ω) of matter: They see "where the atoms are and what the atoms do" (λn~Å and En~me. V!) Main difference to the mp 3 method: Neutrons deliver a genuine 3 D-quantum movie ρ(x, t) ↔ S(q, ω), but take ensemble averages. Transition from classical to quantum physics via: Energy E = ħω, momentum p = ħq Uncertainty relations: ħΔω·Δt = ΔE·Δt ~ ħ ħΔq·Δx = Δp·Δx ~ ħ 22. 05. 2019 The neutron as a tool, and the neutron as an object 8

Different neutron instruments for: - Elastic and inelastic scattering (for diffraction S(q) and spectroscopy, S(q, ω)) - Large angle and small angle scattering (for small and large objects), - For coherent and incoherent scattering (see below) - For nonmagnetic and magnetic scattering, - Using thermal and cold neutrons, in all combinations, this gives ~ 25 ≈ 30… 40 instruments. Different q and ω ranges in S(q, ω): 22. 05. 2019 The neutron as a tool, and the neutron as an object 9

An ensemble of particles can be excited coherently … … or incoherently La Ola λ Neutrons can distinguish between Scoh(q, ω) and Sinc(q, ω)! 22. 05. 2019 The neutron as a tool, and the neutron as an object 10

The ~ 25 instruments of Institute Laue Langevin, Grenoble: For all types of matter: Metals, superconductors, soft matter, biomolecules, minerals, nanomaterials, … used by: physicists, chemists, biologists, geologists, … Mixed teams from all universities and countries 22. 05. 2019 The neutron as a tool, and the neutron as an object 11

Grenoble: ILL ↓ (neutrons) ESRF ↓ (X-rays) 22. 05. 2019 The neutron as a tool, and the neutron as an object 12

How do neutrons give us S(q, ω)? Due to momentum and energy conservation: A change in the system's wavevector q and oscillation ω reappears as a change in the neutron's momentum (as derived from its scattering angle θ and wavelength λ) and kinetic energy (as derived, e. g. , from neutron To. F). In this way, neutron scattering supplies the scattering function S(q, ω). IN 5 at ILL: 22. 05. 2019 The neutron as a tool, and the neutron as an object Scattering angle θ To. F 13

Neutron scattering − one example: Lipoproteins in the blood provide cholesterol and fat for peripheral tissue. D 2 O Their shapes were measured with SANS at PSI, their dynamics with quasielastic n-scattering on IN 5 and IN 6 at ILL, their flexibility ("mean square displacement") with incoherent elastic scatterung on IN 13 at ILL, to find out "where the atoms are and what they do" (in D 2 O solution, pressures up to 3000 bar!) J. Peters, N. Martinez, B. Lehofer, R. Prassl, Institute for Biophysics, U. Graz, U. Grenoble, ILL, PSI, Eur. Phys. J. E 40, 68 (2017) Results: Good lipoprotein is not affected by pressure, is well adapted to extreme external conditions. Bad lipoprotein shows strong changes (× 2) in its dynamics and flexibility, is less adapted. Hope: Could help to develop new concepts for diagnosis and therapy. 22. 05. 2019 The neutron as a tool, and the neutron as an object 14

B. The neutron as an object 1. The neutron as a wave (Main topic of this meeting) What impressed me most in recent years: - Simultaneous entanglement of neutron's position, momentum and spin to form a GHZ-state with one single particle! - A new basis for the uncertainty relation (Ozawa) - Stability of Berry's phase against perturbations, + … 22. 05. 2019 The neutron as a tool, and the neutron as an object 15

2. The neutron as a particle Some trivia on the standard model of particle physics: Nature consists of point particles: Interesting, OK 22. 05. 2019 The neutron as a tool, and the neutron as an object 16

The standard model − more interesting: Very small input: SYMMETRIES: Gauge principle: ψ'(x) = eiφ(x)ψ(x), etc. = symmetry under arbitrary phase modulations: Very rich output: INTERACTIONS: → Equations of motion (Dirac, Schrödinger, Maxwell, Newton) → Existence of photons, gluons, W±, Z 0 (= mediators of interactions) → Conservation of charges (= sources of interactions) But SM is not the full picture … many open questions 22. 05. 2019 The neutron as a tool, and the neutron as an object 17

Neutron particle physics: one example Ultracold neutrons: Free fall of the neutron: quantized version Example: 1↔ 3 and 1↔ 4: 22. 05. 2019 The neutron as a tool, and the neutron as an object 18

Gravitational Resonance Spectroscopy and Dark Energy These transitions are very sensitive to Dark Energy interactions Results: G. Cronenberg, P. Brax, H. Filter, P. Geltenbort, T. Jenke, G. Pignol, M. Pitschmann, M. Thalhammer, H. Abele, TU Vienna, U. Saclay, ILL Grenoble, Nature 14, 1022, Oct. 2018 22. 05. 2019 The neutron as a tool, and the neutron as an object 19

Addendum on neutron decay Low-energy physics n-decay: d → ue−νe High-energy physics p-anti p: dū → e− νe Both reactions are linked by Effective Field Theory. Sometimes LEP better, sometimes HEP. Recent issue: Is the n-lifetime anomaly due to dark decays of the neutron? 2018 -19: more than 20 publications, mostly PRL, Nature, Science. Based on n-decay data by Märkisch, Abele, et al. , PRL "Ed's. suggestion", in print: Result: 22. 05. 2019 The neutron as a tool, and the neutron as an object 20

Neutrons as a tool, Neutrons as an object (wave or particle): Neutrons regularly produce exciting results, in many fields, at the forefront of science. The Atominstitut and Austria are strong players in these fields. My congratulations to Helmut Rauch! Thank you for your attention 22. 05. 2019 The neutron as a tool, and the neutron as an object 21

20 sec. Werbung "Quantum Physics: The Bottom-Up Approach" From the Simple Two-Level System to Irreducible Representations D. Dubbers and H. -J. Stöckmann On Generalized spin precession equations, etc. , see also: New J. Phys. 16, 053050 (2014) "Fröhliche Wissenschaft" u. a. über meine Zeit am ILL, auf Anfrage 22. 05. 2019 The neutron as a tool, and the neutron as an object 22