The A4 experiment

The A4 Collaboration at the electron accelerator facility MAMI measures parity-violating asymmetries in (quasi-)elastic electron scattering off hydrogen or deuterium to determine the strangeness contribution to the vector form factors of the proton. The control of systematic effects like helicity correlated beam fluctuations and the determination of the electron beam polarization are crucial issues. Recently, backward angle measurements at Q2 = 0.23 GeV2 with a deuterium target and forward angle measurements with a hydrogen target at Q2 = 0.62 GeV2 have been analyzed. The preliminary results are presented here

Dvofotonska fizika u MAMI

The structure of the nucleon can be described by the electromagnetic form factors GE and GM. These form factors can be determined by elastic electron-proton scattering with the well-known Rosenbluth technique. Alternatively, the ratio of the electric and the magnetic form factors GE/GM can be determined by the socalled polarization-transfer technique. The measurements reveal a large discrepancy between the two methods at large momentum transfers. There is evidence that twophoton exchange contributions to the elastic scattering have been underestimated. While the two-photon exchange amplitude is difficult to compute from theory due to the excited intermediate hadronic states, its imaginary part can be accessed experimentally by measuring the asymmetry A⊥ in the cross section of elastic ep scattering where the electrons are transversely polarized parallel or antiparallel to the normal of the scattering plane, respectively. The PVA4 experiment at MAMI is currently performing such measurements covering a large range of momentum transfers.Struktura nukleona opisuje se elektromagnetskim faktorima oblika GE i GM. Ti se faktori oblika određuju elastičnim raspršenjem elektrona na protonima poznatom Rosenbluthovom metodom. Druga metoda je određivanje omjera električnog i magnetskog faktora oblika GE/GM primjenom takozvane metode prijenosa polarizacije. Mjerenja pokazuju velike razlike ove dvije metode pri velikim prijenosima impulsa. Neki podaci ukazuju da su doprinosi dvofotonske izmjene elastičnom raspršenju bili podcijenjeni. Teorijsko određivanje amplitude dvofotonske izmjene je vrlo teško zbog uzbudnih hadronskih međustanja. Međutim, imaginarni dio amplitude može se odrediti mjerenjem asimetrije A⊥ udarnog presjeka elastičnog ep raspršenja, u kojemu su elektroni poprečno polarizirani u smjeru odnosno suprotno u odnosu na okomicu na ravninu raspršenja. Eksperiment PVA4 u MAMI provodi ta mjerenja za široko područje prijenosa impulsa

Qualitative Anforderungen an Plankrankenhäuser - Gestaltungsmöglichkeiten der Bundesländer

QUALITATIVE ANFORDERUNGEN AN PLANKRANKENHÄUSER - GESTALTUNGSMÖGLICHKEITEN DER BUNDESLÄNDER Qualitative Anforderungen an Plankrankenhäuser - Gestaltungsmöglichkeiten der Bundesländer / Baunack, Sebastian (Rights reserved) ( -

Biomimetic microelectronics for regenerative neuronal cuff implants

Smart biomimetics, a unique class of devices combining the mechanical adaptivity of soft actuators with the imperceptibility of microelectronics, is introduced. Due to their inherent ability to self‐assemble, biomimetic microelectronics can firmly yet gently attach to an inorganic or biological tissue enabling enclosure of, for example, nervous fibers, or guide the growth of neuronal cells during regeneration

Direct transfer of magnetic sensor devices to elastomeric supports for stretchable electronics

A novel fabrication method for stretchable magnetoresistive sensors is introduced, which allows the transfer of a complex microsensor systems prepared on common rigid donor substrates to prestretched elastomeric membranes in a single step. This direct transfer printing method boosts the fabrication potential of stretchable magnetoelectronics in terms of miniaturization and level of complexity, and provides strain‐invariant sensors up to 30% tensile deformation

High-performance magnetic sensorics for printable and flexible electronics

High‐performance giant magnetoresistive (GMR) sensorics are realized, which are printed at predefined locations on flexible circuitry. Remarkably, the printed magnetosensors remain fully operational over the complete consumer temperature range and reveal a giant magnetoresistance up to 37% and a sensitivity of 0.93 T−1 at 130 mT. With these specifications, printed magnetoelectronics can be controlled using flexible active electronics for the realization of smart packaging and energy‐efficient switches

Measuring the weak mixing angle with the P2 experiment at MESA

The P2 experiment in Mainz aims to measure the weak mixing angle in electron- proton scattering to a precision of 0.13 %. In order to suppress uncertainties due to proton structure and contributions from box graphs, both a low average momentum transfer $Q^2$ of $4.5\cdot 10^{-3}$ GeV$^2/c^2$ and a low beam energy of 155 MeV are chosen. In order to collect the enormous statistics required for this measurement, the new Mainz Energy Recovery Superconducting Accelerator (MESA) is being constructed. These proceedings describe the motivation for the measurement, the experimental and accelerator challenges and how we plan to tackle them.Comment: Proceedings of the PhiPsi15, Sep. 23-26, 2015, Hefei, Chin