Characterization of the JUDIDT Readout Electronics for Neutron Detection

The Group for the development of neutron and gamma detectors in the Central Institute of Engineering, Electronics and Analytics (ZEA-2) at Forschungszentrum Juelich (FZJ) has developed, in collaboration with European institutes, an Anger Camera prototype for improving the impact point reconstruction of neutron tracks. The detector is a chamber filled with $^3He+CF_4$ gas for neutron capture and subsequent production of a tritium and a proton. The energy deposition by the ions gives rise to drifting electrons with an avalanche amplification as they approach a micro-strip anode structure. The scintillating light, generated during the electron drift and avalanche stage, is collected by four vacuum photomultipliers. The position reconstruction is performed via software algorithms. The JUDIDT readout electronics was modified at ZEA-2 to cope with the data acquisition requirements of the prototype. The results of the commissioning of the electronics are here presented and commented.Comment: Corresponding Author: R. Fabbri; 22 pa

Calculation of the Activity Inventory of Transportable Radionuclides in Soil and Groundwater for Large Neutron Sources

EURISOL DS/Task5/TN-07-0

Morphology, input–output relations and synaptic connectivity of Cajal–Retzius cells in layer 1 of the developing neocortex of CXCR4-EGFP mice

Layer 1 (L1) neurons, in particular Cajal–Retzius (CR) cells are among the earliest generated neurons in the neocortex. However, their role and that of L1 GABAergic interneurons in the establishment of an early cortical microcircuit are still poorly understood. Thus, the morphology of whole-cell recorded and biocytin-filled CR cells was investigated in postnatal day (P) 7–11 old CXCR4-EGFP mice where CR cells can be easily identified by their fluorescent appearance. Confocal-, light- and subsequent electron microscopy was performed to investigate their developmental regulation, morphology, synaptic input–output relationships and electrophysiological properties. CR cells reached their peak in occurrence between P4 to P7 and from thereon declined to almost complete disappearance at P14 by undergoing selective cell death through apoptosis. CR cells formed a dense and long-range horizontal network in layer 1 with a remarkable high density of synaptic boutons along their axons. They received dense GABAergic and non-GABAergic synaptic input and in turn provided synaptic output preferentially with spines or shafts of terminal tuft dendrites of pyramidal neurons. Interestingly, no dye-coupling between CR cells with other cortical neurons was observed as reported for other species, however, biocytin-labeling of individual CR cells leads to co-staining of L1 end foot astrocytes. Electrophysiologically, CR cells are characterized by a high input resistance and a characteristic firing pattern. Increasing depolarizing currents lead to action potential of decreasing amplitude and increasing half width, often terminated by a depolarization block. The presence of membrane excitability, the high density of CR cells in layer 1, their long-range horizontal axonal projection together with a high density of synaptic boutons and their synaptic input–output relationship suggest that they are an integral part of an early cortical network important not only in layer 1 but also for the establishment and formation of the cortical column

Current-induced magnetization switching in a model epitaxial Fe/Au bilayer

In electronics, the application of novel spintronic three-terminal memory devices is proposed to facilitate further improvements of the performance of electronic components. A promising write-mechanism in a spintronic memory is based on the purely electricalswitching of the magnetization by $\textit{spin-orbit torque}$ (SOT) that can occur, for example, at the interface of heavy metal (HM)/ferromagnetic metal (FM) bilayers. This thesis presents a study of the epitaxial model HM/FM system Au(4 nm)/Fe(1- 1.5 nm)/MgO(001) using magneto-transport measurements and Kerr microscopy. The Au/Fe bilayers were photolithographically patterned into Hall bars in order to study their magnetic and magneto-transport properties. The Au/Fe bilayer Hall bars on MgO(001) substrate exhibit a strong in-plane easy magnetization axis and a cubic magnetic anisotropy in the film plane dominated by the magneto-crystalline term of the Fe(001) layer. In the chosen geometry of the samples the easy magnetization directions coincide with the extrema of the transversal voltage induced by the planar Hall effect (PHE). Therefore, a switching of the magnetization from one easy direction to another can be detected by measuring the PHE-voltage. Furthermore, Kerr microscopy revealed the formation of stripe-shaped magnetic domains separated by 90$^\circ$ domain walls aligned perpendicular to the Hall bar. A combined measurement of PHE-voltage and acquisition of Kerr images has shown that the measured PHE-voltage is most considerably affected by the domain configuration within the central area of the Hall cross. Based on this findings, the influence of electrical currents on the magnetization in the Fe(001) layer was investigated via measurements of the PHE combined with Kerr microscopy. At room temperature, a current density beyond 10$^{7}$ A/cm$^{2}$ induces an Oersted field, which in the Fe(001) layer points in-plane in the direction perpendicular to the long axis of the Hall bar and can exceed the coercive field B$_{c}$=0.65$\pm$0.05 mT for the 90$^\circ$ switch of the magnetization. Moreover, a current density beyond 1.4$\cdot$10$^{7}$ A/cm$^{2}$ with an alternating polarity can be employed for reproducible electrical switching of the magnetization in the Au/Fe/MgO(001) Hall bars between multiple stable states. Kerr microscopy confirmed that a variation of the applied current density changes the domain structure at the Hall bar cross. The change of the domain structure scales with the applied current density and can be read-out as a change in the PHE-voltage. The PHE measurements at T<50 K indicate a presence of an additional current-induced field up to 2.5 mT in the direction normal to the film surface

EMI Registry Requirements Specification and Architecture V.0.2

This document describes the requirements and specification for a service discovery mechanism and the EMI Registry as proposed solution to this problem