Sub-micron defects represent a well-known fundamental problem in manufacturing since they can significantly affect performance and lifetime of virtually any high-value component. Positron annihilation spectroscopy is arguably the only established method capable detecting down to sub-nanometer scale but, date, it works for surface studies, with limited resolution. Here, we experimentally numeric...

Abstract We present a hybrid imaging/timing detector for force sensitive inertial measurements designed on positronium, the metastable bound state of an electron and positron, but also suitable applications involving other low intensity, energy beams neutral (antimatter)-atoms, such as antihydrogen. The performance prototype was evaluated with tunable positron beam, resulting in spatial resolut...

We show that our recent SU(4) generalized “rishon” composite model for quarks and leptons, augmented either by the hypothesis of breaking of color SU(3) to “glow” SO(3), or by the hypothesis of incomplete color neutralization in very hard processes, leads to an interpretation of the HERA positron-jet events as the production by color gluon exchange, followed by the decay by color gluon emission...

High-temperature positron two-dimensional angular correlation of annihilation radiation ~2D-ACAR! measurements have recently been succesfully applied to map parts of the Fermi surface of YBa2Cu3O72d . Using the same principle, we have been able to observe with a bulk sensitive method, the Fermi surface of Nd22xCe xCuO42d . Although positron trapping by defects and correlation effects are strong...

Positron binding to molecules is compared to the analogous electron-molecule bound states. For both, the bound lepton density is diffuse and remains outside the valence shell. Positron binding energies are found to be one to two orders of magnitude larger than those of the negative ions due to two effects: the orientation of the molecular dipole moment allows the positron to approach it more cl...

A method is proposed for detecting positron-atom bound states by observing enhanced positron annihilation due to electronic Feshbach resonances at electron-volt energies. The method is applicable to a range of open-shell transition-metal atoms which are likely to bind the positron: Fe, Co, Ni, Tc, Ru, Rh, Sn, Sb, Ta, W, Os, Ir, and Pt. Estimates of their binding energies are provided.

We describe some of the measurements that will be performed to study the physics of the self-modulation instability of electron and positron bunches. These measurements will be performed at SLAC-FACET in the E209 experiment. The effect of the SMI on the drive bunch itself (electron or positron) will be studied. Differences between electron and positron bunches are expected since the wakefields ...

Standard pre-treatment clinical staging (TNM) of head and neck squamous cell carcinoma includes clinical and instrumental objective examination of primary tumour and of the cervical lymph nodes (inspection, palpation of neck, panendoscopy, biopsy of tumour, fine needle aspiration of nodes) and computed tomography or magnetic resonance imaging. Albeit, this procedure presents diagnostic limitati...