MLZ is a cooperation between:

> Technische Universität München> Helmholtz-Zentrum Geesthacht> Forschungszentrum Jülich
> MLZ App

MLZ (eng)

Lichtenbergstr.1
85748 Garching

# Projects funded by the German Research Foundation (DFG)

UCN: Ultra cold neutrons - Fundamental physics with neutrons

Proposer: Excellence Cluster Universe, Garching
Grant period: 2006 – 2017

Description/Objective:
Within the Cluster of Excellence “Origin and Structure of the Universe”, the group around Prof. Dr. Paul and Prof. Dr. Fierlinger deals with experiments that should help scientists understand the fundamental physics at work in the early Universe. The focus is directed towards topics such as the nature of the excess of matter versus antimatter, the investigation of the neutron electric dipole moment, and the standard model of physics. The funded projects within this grant period include preliminary or additional experiments within the project „SPP 1491: Precision experiments in particle and astrophysics with cold and ultracold neutrons“ funded by the DFG for the period 2010-2013.

Detailed information about ongoing research and projects within the Excellence Cluster Universe can be found here:

http://www.universe-cluster.de/fierlinger/

Microscopic understanding of the structure and dynamics of self-healing macromolecules

Proposer: Forschungszentrum Jülich
Project-no.: Subproject within SPP 1568: Design and Generic Principles of Self-Healing Materials
Grant period: 2011 -

Description/Objective:
The contribution of FZJ aims at a microscopic understanding of new polymeric systems which are predicated on reversible crosslinking through hydrogen bonding. These are prominent key actors for the design of novel self-healing properties which counteract damage processes directly and autonomously on the molecular level. A microscopic understanding of the self-healing process is feasible only by a combination of neutron scattering and complementary laboratory macroscopic techniques. Due to the exquisite sensitivity of neutron scattering to both, relevant length scales and time scales, local and global structure and dynamics relating to the character of reversible hydrogen-bonding itself and its implication for emerging new elastic macroscopic properties respectively will be addressed. In the systems to be investigated the reactive end groups and basic monomer chemistry will be varied along a polarity scheme which affects the bonding energy. Given the similarity of the H-bonding entities, the expected results apply also to the basic chemistry of parallel proposals to this DFG call and allow generalization and finally controlled design of new adaptive high-performance composites.

The Influence of Surfaces and Confinement on the Dynamics of Polymer Melts

Proposer: Forschungszentrum Jülich
Project-no.: Subproject within SPP 1369: Polymer-Festkörper-Kontakte: Grenzflächen und Interphasen
Grant period: 2011 -

Description/Objective:
The aim of the work is to study the influence of the surfaces and their interaction with polymers at the interface and the confinement resulting from the interfaces in nanoporous systems on the dynamics of polymer melt by neutron scattering methods. The confining systems are presented by well-ordered cylindrical nanopores (2D confinement) of anodic aluminum oxide (AAO) and porous silicon (PSi). We will focus on the segmental dynamics on the local time scale measured by quasielastic neutron scattering (QENS) up to a few nanoseconds and on the large scale dynamics measured by high resolved neutron spin-echo (NSE) spectroscopy extending the time scale to a few hundred of nanoseconds. The main goal of the project is investigation of the influence of the confining surfaces and geometrical confinement on the structure and dynamics of polymer chains at the interface and their extent into a possible interphase for different types of interaction between solid walls and the melt. In particular, we will study the influence of the surface on the local segmental dynamics, unentangled Rouse dynamics and the polymer entanglement network changing the properties of the surfaces by means of chemical treatment. The neutron scattering results will be supplemented by NMR, broadband dielectric spectroscopy (BDS), bulk rheological studies and computer simulations.

TRR 80: From Electronic Correlations to Functionality

Proposer: University of Augsburg, Technische Universität München, Ludwig-Maximilians-Universität München, Walther-Meißner-Institute of the Bavarian Academy of Sciences
Partner: Max Planck Institute for Solid State Research, Stuttgart
Grant period: 2010 – 2013

Description/Objective:
The Transregional Collaborative Research Centre (TRR) has been established by the German Research Foundation (DFG). The Transregio TRR 80 “From Electronic Correlations to Functionality“ funded by the DFG for four years, started in 2010. An extension of the funding for up to 12 years is expected. The TRR 80 comprises four scientific project areas, covering advanced techniques, novel electronic states, interfaces and functionality. It brings together experimentalists and theoreticians all working on complex materials in the Munich-Augsburg region. Besides the research programme, the Transregio includes high priority tasks such as an integrated graduate school, programs for gender equality, public outreach and industrial collaborations.

The Transregio TRR 80 will examine new materials, which could revolutionize electronic parts or magnetic storage materials. Seven out of 17 projects of the Transregio will use neutrons and positrons at the FRM II to characterize new phenomena.

The following projects of the TRR80 will make use of neutrons and positrons at the FRM II:

A1: Single Crystal Growth of Metals with Complex Order
A3: Determination of Electronic Structure Using Positrons
A5: Neutron Reflectometry on Magnetic Layers
A6: Stabilizing magnetic order under extreme conditions
C1: Magnetic Order and Reconstruction at Oxide Interfaces
D3: Manipulation of Electronic Interactions in Heterostructures through Stress Tuning

http://www.trr80.de/trr80/index.php?ID=2000

Electric Fatigue in Functional Materials: "in operando" investigation of fatigue in commercial batteries

Proposer: Technische Universität Darmstadt, Karlsruhe Institute of Technology (KIT)
Partner: Technische Universität München/FRM II
Grant period: 01/2011 – 12/2013
Project-no.: SFB595/T1

Description/Objective:
Li-ion battery technology is today the most common storage media for portable electronics, offering the most promising concept for the storage of renewable energy in terms of, for example, electric drivelines for hybrid and electric vehicles. Despite its simple principle of operation, nowadays a typical lithium ion battery is a complex device. An understanding of the underlying processes and relevant fatigue mechanism is key for optimized or new Li-ion batteries with enhanced performance. The transfer project focuses on “in operando” (under real operation conditions) studies of commercial Li-ion batteries using non-destructive methods such as neutron diffraction and tomography. Based on an understanding of the fatigue in real commercial devices, concepts for improved materials can then be proposed.

Physics of colloidal dispersions in external fields

Proposer: Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Johannes Gutenberg University Mainz, Max Planck Institute for Polymer Research Mainz, University of Konstanz
Partner: Utrecht University
Grant period: 07/2009 – 06/2013
Project-no.: SFB/TR 06

Description/Objective:
Within the Transregio Collaborative Research Centre TR6 the joint collaboration partners focus on the rich physics of colloidal dispersions. The latter are solutions of mesoscopic solid particles with a stable (i.e. non-fluctuating) core embedded in a molecular fluid solvent. Among the various soft matter systems, colloidal dispersions play a prominent role as they can be both prepared and characterized in a controlled way. The effective interaction between the colloidal particles can be tailored by making specific alterations, for example, changing the salt concentration in the solvent.
Fascinating questions arise concerning the collective many-body effects induced by the cooperation and self-organization of many particles. A striking advantage of colloidal dispersions lies in the fact that these questions can be studied simultaneously by using three different complementary methods, namely experiment, computer simulation, and theory.

BOB - The bound beta decay of the free neutron

Proposer: Technische Universität München, E18
Grant period: 03/2010 – 05/2013
Project-no.: SPP 1491

Description/Objective:
The classical neutron three-body ß-decay was studied to determine decay rates and decay asymmetries with great precision. However, this project, shortly termed BOB, aims at the detection of a new decay branch of the neutron, namely the two-body decay into a hydrogen atom and an electron antineutrino: $n\to H+\overline{{\nu }_{e}}$ expected with a branching ratio of about 4·10-6 of the standard decay. This decay has the potential to offer new access to the measurement of the coupling scheme of weak interaction and constitutes a direct measurement of the ve in beta decays. Hydrogen atoms emerging from a neutron source (FRMII in Munich) shall be spectroscopically analysed and detected, and from these experiments the branching ratio of the bound beta-decay shall be determined.

OILL - Investigations of magnetic field related systematic effects on the measurements of the electric dipole moment of the neutron in the OILL-Experiment

Proposer: Technische Universität München, E18
Grant period: 03/2010 – 05/2013
Project-no.: SPP 1491

Description/Objective:
A new generation experiment to measure a limit for the electric dipole moment of the neutron (nEDM) on the 10-28e•cm level requires magnetic shielding on an unprecedented level. Due to its magnetic moment, the neutron is affected by the earth magnetic field as well as by other ambient magnetic field fluctuations and gradients.

The nEDM collaboration was given access to the old RAL/Sussex/ILL group apparatus (OILL) located at ILL, the one which was used to measure the current best value of the neutron EDM. The collaboration plans to further advance the techniques of nEDM measurements, using the old spectrometer in the initial phase of the project. The sensitivity improvement will be achieved mainly due to the high UCN flux of planned sources such as the PSI or FRM II UCN sources (an improvement of two orders of magnitude over the present ILL source). Main developments leading to better control over systematic effects contain additional magnetometry systems and better magnetic shielding and stabilization.

PENeLOPE - Lifetime of the free neutron

Proposer: Technische Universität München, E18
Grant period: 03/2010 – 05/2013
Project-no.: SPP 1491

Description/Objective:
Whereas within a nucleus, bound neutrons are stable, free neutrons are unstable. They undergo so called beta decay, thereby decaying into a proton with the emission of an electron and electron antineutrino. The lifetime of the free neutron is one of the fundamental physical constants and plays an important role in many areas of physics. In the experiment PENeLOPE (Precision Experiment on the Neutron Lifetime Operating with Proton Extraction), ultra-cold neutrons shall be stored magnetically in a trap and neutron lifetime shall be determined. The magnetic fields are created by superconducting magnets, thereby avoiding losses not fully understood at material walls. The experiment PENeLOPE will be filled with ultra-cold neutrons from the new UCN source at the FRM II, which can generate UCN densities in the experiment two orders of magnitude higher than the strongest UCN source currently available at ILL.
The project dealing with the lifetime of the free neutron consists of the following two subprojects funded by the DFG:

EDM - Realization of a magnetically shielded environment for a new measurement of the electric dipole moment of the neutron

Proposer: Technische Universität München, E18
Grant period: 03/2010 – 05/2013
Project-no.: SPP 1491

Description/Objective:
Contemporary neutron research often requires highly stable conditions in experimental environments. In particular, the neutron’s magnetic moment is affected by the earth’s magnetic field as well as by other ambient magnetic field fluctuations and gradients. Manifestations of this problem are evident in fundamental experiments such as the measurement of the electric dipole moment (EDM) of the neutron, where knowledge of the magnetic field is a crucial parameter of the experiment.
To measure the electric dipole moment of the neutron (nEDM), magnetically highly shielded environments, to be developed within this project, are crucial to decrease systematic false effects. A non-zero electric dipole moment is an unambiguous manifestation of time-reversal symmetry violation and contributes to the explanation of the baryon-asymmetry in the universe. Currently, several approaches towards an improvement of the limit on the nEDM are on the way, where the TUM participates in an approach based on stored ultra-cold neutrons at room temperature.
The project dealing with EDM consists of the following three subprojects funded by the DFG:

SQUID - Development of a miniaturized SQUID measuring system for an experiment to measure the electric dipole moment of the neutron

Proposer: Technische Universität München, E18
Grant period: 03/2010 – 05/2013
Project-no.: SPP 1491

Description/Objective:
In a next generation experiment to measure the electric dipole moment of the neutron (nEDM) accurate control of magnetic fields is crucial. In particular, the vertical gradient through the neutron storage chamber needs to be determined precisely to avoid so-called geometric phases, which appear in combination with systematic trajectories of stored ultra-cold neutrons (UCN) in the chamber. These are interpreted as false EDM Signals and have been observed on the level of 10-26 e cm in the previous generation of experiments. Based on recently developed large volume 3He spin precession chambers, such a gradient can be determined with great accuracy. However, these 3He chambers must also be read out using magnetometers. Within the framework of this proposal, it is planned to develop a miniaturized SQUID System to read out 3He precession signals.

UCN infrastructure - Helium cryogenic plant with ancillary equipment

Proposer: Excellence Cluster Universe
Grant period: 2009 – 2013

Description/Objective:
The project is funded by the DFG and the state of Bavaria. Its aim is to build an infrastructure for a laboratory for ultra-cold neutron research at the FRM II. This infrastructure including a helium cryogenic plant with ancillary equipment is essential for the construction of an ultra-cold neutron source and related experiments (measurement of the electric dipole moment and the lifetime of the neutron). The helium refrigeration system will consist of 3 He coolers/condensers, the necessary compressors, one transformer with a control unit and a cooling system. Hereby, the appropriate cooling capacity of liquid helium quantities can be generated, necessary for the intended experiments.

Experimental analysis of tri-axial residual stress fields after laser hardening

Proposer: Institute for Applied Materials, KIT; FRM II, TUM
Grant period: 10/2011 – 09/2013
Project-no.: DFG HO 3322/2-1

Description/Objective:
Laser hardening is a modern surface process which is used to enhance the hardness profile of steel components and to introduce beneficial compressive surface stresses. Compared to conventional hardening techniques it also ensures better process control and predictability of quality.
The experimental determination of the ensuing 3D stress fields after laser hardening from the surface into the depth of the components is not possible with standard methods like X-ray diffraction.
In this project, the aim is therefore to develop a methodology for residual stress analysis using neutron diffraction which will not suffer from aberration effects, usually observed with neutron measurements close to surfaces. The use of novel neutron optics such as focusing guides and radial collimators together with optimising instrumental parameters such as monochromator focusing conditions (via simulations) on the instrument STRESS-SPEC will allow these surface effects to be minimized while also considerably improving the spatial resolution (<< 1 mm3). These settings can then be used for complete determination of residual stress fields introduced by laser hardening in steel components using neutron diffraction.

UCN source - Source for ultra-cold neutrons at the FRM II

Proposer: Excellence Cluster Universe
Grant period: 2006 – 2012

Description/Objective:
Precision experiments with ultra-cold neutrons (UCN), such as the search for a possible electric dipole moment (EDM) of the neutron or the measurement of the lifetime of the free neutron, require high UCN densities. Stronger UCN sources are presently developed worldwide, based on the principle of superthermal UCN production using cryo-converters made of solid deuterium (sD2) or superfluid helium. At the FRM II, a UCN source with a sD2 converter and sH2 pre-moderator at a temperature of 5 K, placed in a distance of 60 cm from the central fuel element inside the horizontal, tangential end-to-end beam tube SR6, is currently under construction. It can generate UCN densities of 104cm-3 in up to four connected experiments. These densities are more than two orders of magnitude higher compared to the currently strongest UCN source at the ILL. Operated in continuous mode, the UCN source can deliver a flux density of 6•105cm-2s-1 to connected experiments.

http://www.e18.ph.tum.de/research/ucn/

In-situ residual stress analysis in composite castings using neutron diffraction

Proposer: FRM II, TUM; Lehrstuhl für Umformtechnik und Gießereiwesen (utg), TUM
Grant period: 05/2011 – 10/2012
Project-no.: DFG PE 580/12-1

Description/Objective:
The composite casting process is mainly used to produce composite engine blocks with in-cast liners. Due to the differences in the thermal expansion of the casting material (usually an Al-alloy) and the material of the insert (steel), residual stresses occur during solidification. Using time-resolved in-situ neutron diffraction on model components at STRESS-SPEC it will be possible to investigate how these residual stresses evolve in composite Al castings. Here the central question will be how the residual stresses distribute and stress relaxation occurs during cooling, as this is not properly considered in current simulation models. The results of the in-situ investigations will be used to develop material models to improve the prediction of residual stresses from FEM-simulations in real life composite components.

MLZ is a cooperation between:

> Technische Universität München> Helmholtz-Zentrum Geesthacht> Forschungszentrum Jülich
> MLZ App