Hypernuclear Physics at PANDA

Hypernuclear research will be one of the main topics addressed by the PANDA experiment at the planned Facility for Anti-proton and Ion Research FAIR at Darmstadt, Germany. A copious production of Xi-hyperons at a dedicated internal target in the stored anti-proton beam is expected, which will enable the high-precision gamma-spectroscopy of double strange systems for the first time. In addition to the general purpose PANDA setup, the hypernuclear experiments require an active secondary target of silicon layers and absorber material as well as high purity germanium (HPGe) crystals as gamma-detectors. The design of the setup and the development of these detectors is progressing: a first HPGe crystal with a new electromechanical cooling system was prepared and the properties of a silicon strip detector as a prototype to be used in the secondary target were studied. Simultaneously to the hardware projects, detailed Monte Carlo simulations were performed to predict the yield of particle stable hypernuclei. With the help of the Monte Carlo a procedure for Lambda-Lambda-hypernuclei identification by the detection and correlation of the weak decay pions was developed.Comment: prepared for the International Conference on Exotic Atoms and Related Topics (EXA2011), Vienna, Sept. 5-9, 201

Analytical model for the ohmic-side interstrip resistance of double-sided silicon microstrip detectors

A compact, analytical model is derived for the n-side interstrip resistance of double-sided silicon microstrip detectors, allowing for fast and accurate prediction of the minimum p-stop (or p-spray) implant dose ensuring adequate interstrip isolation. The basic idea on which the proposed model relies is that the portion of the detector between two adjacent n-strips can effectively be reduced to an equivalent n-channel MOSFET. The interstrip resistance can be evaluated as the output resistance of this equivalent MOSFET using standard SPICE-like models. The influence of radiation-induced oxide charge and p-stop (or p-spray) voltage can be accounted for by simply including, in the threshold voltage expression, the induced flat-band voltage shift and body-effect term, respectively

RD on 3D Sensors and Micro‐Fabricated Detector Systems

The aim of this proposed R&D Collaboration is the design, fabrication and industrialization of a new generation of low mass detector systems based on silicon micro‐fabrication techniques. The main objective is the verification and validation of such systems for LHC detector upgrades. In particular, the collaboration would like to focus on the following research topics: • Novel 3D sensors layouts, with enhanced signal properties, high speed and active edges. • Integrated micro‐channel cooling for effective low mass module thermal management. • System integration and fully sensitive large area coverage

Enhancement of RF-MEMS switch reliability through an active anti-stiction heat-based mechanism

MicroElectroMechanical Systems for Radio Frequency applications (i.e. RF-MEMS) show very good performance and characteristics. However, their employment within large-scale commercial applications is still limited by issues related to the reliability of such components. In this work we present the Finite Element Method (FEM) modelling and preliminary experimental results concerning an active restoring mechanism, embedded within conventional MEMS/RF-MEMS ohmic (and capacitive) relays, capable of retrieving the normal operation of the switch if stiction occurs (i.e. the missed release of an actuated switch when the controlling bias is removed). The mechanism exploits the heat generated by an electric current flowing through an high-resistivity poly-silicon serpentine (Joule effect), to induce deformations in the suspended MEMS structures. Such changes in the mechanical structure result in shear and vertical restoring forces, helping the membrane release. The FEM-based thermo-electromechanical simulations discussed in this work include the coupling between different physical domains, starting from the imposed current, to the MEMS deformation. The preliminary experimental data reported in this paper show a speed-up of the dielectric discharge time due to the generated heat, as well as a change in the S-parameters, due to the membrane expansion, compatible with an upward bending of the central contact (i.e. restoring force), useful to counteracting stiction due to micro-welding

Laser and alpha particle characterization of floating-base BJT detector

In this work, we investigate the detection properties of existing prototypes of BJT detectors operated with floating base. We report about results of two functional tests. The charge-collection properties of BJT detectors were evaluated by means of a pulsed laser setup. The response to alpha-particles emitted from radioactive (241)Am source are also presented. Experimental results show that current gains of about 450 with response times in the order of 50 mu s are preserved even in this non-standard operation mode, in spite of a non-optimized structure. (C) 2009 Elsevier B.V. All rights reserved