[en] A new strong source for the production of ultra-cold neutrons (UCN) is currently built up at the Forschungsneutronenquelle Heinz Maier-Leibnitz (FRMII). It will be installed at the horizontal beam tube SR-6, with a solid hydrogen pre-moderator and a solid deuterium UCN-converter located approx. 60 cm away from the fuel element. UCN are produced inside the solid deuterium via the superthermal principle of conversion of the pre-cooled neutrons coming from the solid hydrogen. The UCN will be extracted out of the converter and guided through the biological shield to several experiments located inside the experiment halls of the FRMII. These experiments are investigating fundamental properties of the free neutron, such as its lifetime, a possible electric dipole moment or the quantum mechanical interaction of neutrons with the earth's gravitational field field. The expected UCN densities in the experiments will be 2-3 orders of magnitude higher than the densities reached at the currently strongest UCN-source located at the ILL. This talk will give an overview of the setup of the UCN source at the FRM-II, technologies used, and of the connected experiments. The current status of the project and future developments will be presented. (author)

[en] Neutron-induced fission of uranium allows for the production of high-intensity neutron-rich radioactive ion beams. However, also large quantities of unwanted volatile radioactive species are produced that have to be hindered from contaminating the beamline and vacuum system of the facility. In the framework of radioprotection studies within the MAFF project at the FRM II in Garching with 10¹⁴ fiss/sec., the performance of a cryotrap system has been studied, designed to localize gaseous radioactivity close to its origin. These studies provide important radioprotection information for the planned EURISOL facility with 10¹⁵ fission events/sec. Design considerations, activity distribution calculations and a comparison to experimental prototype test results will be presented. (orig.)

[en] PENeLOPE is a new high-precision experiment on the neutron lifetime τ_n planned at the Physik Department of Technische Universitaet Muenchen. Contrary to most lifetime experiments with stored neutrons so far, ultra-cold neutrons (UCN) are contained in a magnetic multipole field created by superconducting coils. The UCN are gravitationally bound in vertical direction, which allows extraction of the decay protons onto a detector. Using these techniques a precision of Δτ_n<0.1s is aimed for. An updated experimental setup of PENeLOPE is presented, simulations and expected systematic effects are discussed.

No abstract available

[en] Marginally trapped neutrons are a major source of systematic errors in storage experiments with ultra-cold neutrons (UCN): their energies slightly exceed the trapping potential and their storage lifetimes are of the same order of magnitude as the neutron β-decay lifetime to be measured. Hence, they have to be removed before the actual neutron storage period starts. For the magneto-gravitational neutron-lifetime experiment PENeLOPE, a novel absorber scheme was proposed; its efficiency to reduce the systematic influence of marginally trapped UCN on the extracted β-decay lifetime value had to be investigated. To this end, the cryogenic material-storage experiment AbEx (Absorber Experiment) was conducted at ILL, Grenoble; neutron-optical properties of storage and absorption materials were investigated. Storage lifetimes shorter than 10 s could be reached for high-energy UCN with the proposed scheme. This translates to a systematic effect on the neutron-lifetime measurement with PENeLOPE of Δτ_n<0.03s. Polyethylene (PE) and titanium were tested as absorber materials. The temperature dependence of their UCN absorbing efficiency was determined to be rather small and connected not with the upscattering cross-section, but probably with surface contaminations.

[en] A versatile and portable magnetically shielded room with a field of (700 ± 200) pT within a central volume of 1 m × 1 m × 1 m and a field gradient less than 300 pT/m, achieved without any external field stabilization or compensation, is described. This performance represents more than a hundredfold improvement of the state of the art for a two-layer magnetic shield and provides an environment suitable for a next generation of precision experiments in fundamental physics at low energies; in particular, searches for electric dipole moments of fundamental systems and tests of Lorentz-invariance based on spin-precession experiments. Studies of the residual fields and their sources enable improved design of future ultra-low gradient environments and experimental apparatus. This has implications for developments of magnetometry beyond the femto-Tesla scale in, for example, biomagnetism, geosciences, and security applications and in general low-field nuclear magnetic resonance (NMR) measurements

[en] We performed ultracold neutron storage measurements to search for additional losses due to neutron (n) to mirror-neutron (n^') oscillations as a function of an applied magnetic field B. In the presence of a mirror magnetic field B^', ultracold neutron losses would be maximal for B≅B^'. We did not observe any indication for nn^' oscillations and placed a lower limit on the oscillation time of τ_nn^'>12.0 s at 95% C.L. for any B^' between 0 and 12.5 μT.

[en] Neutron-induced fission of uranium allows for the production of high-intensity neutron-rich radioactive ion beams. However, also large quantities of unwanted volatile radioactive species are produced that have to be hindered from contaminating the beamline and vacuum system of the facility. In the framework of radioprotection studies within the MAFF project at the FRM II in Garching with 10¹⁴ fission events/s [D. Habs et al., The Munich accelerator for fission fragments MAFF, Nucl. Instr. and Meth. B 204 (2003) 739], the performance of a cryotrap system has been studied, designed to localize gaseous radioactivity close to its origin. These studies provide important radioprotection information for the planned EURISOL facility with 10¹⁵ fission events/s. Design considerations of a compact cryotrap operated with cold helium gas at a saturation temperature around 18 K will be presented. Activity distribution calculations of the fission source, the cryotrap and the subsequent vacuum system result in a prediction of the retention capability of the cryotrap system of 99.98%. These design calculations have been experimentally verified with three cryotrap prototypes differing in cold surface area as well as in their internal helium gas flow characteristics. Retention capabilities have been measured with and without passive shielding of the external thermal load (300 K) using different tracer gases and an inclusive pressure-related diagnostics as well as mass-spectroscopic measurements.

[en] The layout and status of MAFF at the Munich high flux reactor FRM-II is described. At MAFF 1014 fissions/s will be induced by thermal neutrons in a target with approx. 1 g of 235U. The situation is compared to the SPIRAL2 facility where 1014 fissions/s are expected by fast neutron fission in a target containing 5100 g of 238U. A comparison of the yields of SPIRAL2 and MAFF is performed to show the complementarity of the two ISOL-facilities for fission fragments. MAFF has approximately five times the beam intensities of SPIRAL2 for short-lived fission isotopes with lifetimes shorter than 5 s and thus will focus on the most neutron-rich nuclei, while SPIRAL2 has better perspectives for the more intense, less neutron-rich post-accelerated beams.A problem that also deserves attention is the production of α emitters, in particular plutonium. Here MAFF has the advantage to contain the Pu-producing 238U only as impurity not as the main fissile system. If SPIRAL2 would use 235U instead of 238U this problematic issue could be avoided at the cost of a further reduction in intensity of very neutron-rich fission fragments by a factor of 10. Finally new physics close to the classically doubly-magic nuclei 78Ni and 132Sn is described

[en] We present a magnetically shielded environment with a damping factor larger than 1 × 10⁶ at the mHz frequency regime and an extremely low field and gradient over an extended volume. This extraordinary shielding performance represents an improvement of the state-of-the-art in the difficult regime of damping very low-frequency distortions by more than an order of magnitude. This technology enables a new generation of high-precision measurements in fundamental physics and metrology, including searches for new physics far beyond the reach of accelerator-based experiments. We discuss the technical realization of the shield with its improvements in design