The Monitoring System of the Belle II Vertex Detector

The Belle II VerteX Detector (VXD) is a 6 layers silicon tracker device that will cope with an unprecedented luminosity of 8 7 10 35 cm 12 2 s 12 1 achievable by the new SuperKEKB e + e 12 collider, at the KEK laboratory (Tsukuba, Japan). All environment parameters such as temperature, humidity and radiation levels, must be constantly monitored and under certain conditions action must be promptly taken, such as interlocking the power supply or delivering an abort signal to the SuperKEKB collider. In this contribution we describe the Belle II VXD monitoring system. We also present the first results of the temperature and humidity system commissioned in a Beam Test at DESY in April 2016 and the preliminary results of the radiation monitoring achieved with a prototype system during the first SuperKEKB commissioning phase at KEK in February-June 2016

The Software Framework of the Belle II Silicon Vertex Detector and its Development for the 2016 Test-Beam at DESY

The Silicon Vertex Detector of Belle II will be fundamental not only for the reconstruction of B meson vertices, but also for the reconstruction of neutral particles like K S , and the tracking of low- p t particles like slow pions associated with the decays of the abundant D 17 mesons. As a consequence great importance is given to the performance of the software that deals with the simulation and reconstruction of the SVD events. The Belle II experiment is the successor to Belle, one of the two experiments that first observed CP violation in the decay of B mesons. The SuperKEKB collider will deliver 40 times more luminosity than its predecessor KEKB, which requires major upgrades to the detector hardware. This also poses new challenges not only for the data collection and storage, but also for the software framework which is used to process and analyse the experimental data. In this article we present in detail the SVD software framework together with its development for the test of the Vertex Detector system, which took place at DESY in April 2016 using an electron beam

Performance studies of the Belle II Silicon Vertex Detector with data taken at the DESY test beam in April 2016

Belle II is a multipurpose detector currently under construction and it will be operated at the next generation B-factory SuberKEKB in Japan. The main Belle II devices, devoted to the vertex reconstruction, are the Silicon Vertex Detector (SVD) and the Pixel Detector (PXD). In April 2016 a sector of the Belle II SVD and PXD has been tested in a beam of high energetic electrons at the test beam facility at DESY Hamburg (Germany). We report here the results for the hit efficiency estimation and the measurement of the resolution for the Belle II silicon vertex detector. Hit efficiencies are measured to be on average above 99.5% and the measured resolution is within the expectations

The Belle II SVD detector

The Belle II VerteX Detector (VXD) is a 6 layers silicon tracker device that will cope with an unprecedented luminosity of 8 7 10 35 cm 12 2 s 12 1 achievable by the new SuperKEKB e + e 12 collider, at the KEK laboratory The Silicon Vertex Detector (SVD) is one of the main detectors in the Belle II experiment at KEK, Japan. In combination with a pixel detector, the SVD determines precise decay vertices and performs low-momentum track reconstruction. The SVD ladders are being developed at several institutes. For the development of the tracking algorithm as well as the performance estimation of the ladders, beam tests for the ladders were performed. We report an overview of the SVD development, its performance measured in the beam tests, and the prospect of its assembly and commissioning until installation

Characterization of the transient response of diamond sensors to collimated, sub-ps, 1 GeV electron bunches

Diamond sensors (DS) are widely used as solid-state particle detectors, beam loss monitors, and dosimeters in high-radiation environments, e.g., particle colliders. We have calibrated our DS with steady β - and X-radiation, spanning a dose rate in the range 0.1-100 mGy/s. Here, we report the first systematic characterization of transient responses of DS to collimated, sub-picosecond, 1 GeV electron bunches. These bunches, possessing a charge ranging from tens to hundreds of pC and a size from tens of microns to millimeters, are suitably provided by the FERMI electron linac in Trieste, Italy. The high density of charge carriers generated by ionization in the diamond bulk causes a transient modification of electrical properties of DS (e.g., resistance), which in turn affects the signal shape. We have modeled a two-step numerical approach, simulating the effects on the signal of both the evolution of charge carrier density in the diamond bulk and the changes in the circuit parameters. This approach interprets features observed in our experimental results to a great extent

Development of 3D detectors at FBK-irst

We report on the development of 3D detectors at Fondazione Bruno Kessler - irst in the framework of the CERN RD-50 Collaboration. Technological and design aspects dealing with the 3D Single Type Column detectors are reviewed, and selected results from the electrical and functional characterization of prototypes are reported and discussed. A new detector concept, namely 3D Double-side Double Type Column detectors, allowing for significant performance enhancement while maintaining a reasonable process complexity, is final ly addressed

Measurement of Johnson Noise Induced by p-Stops in Silicon Microstrip Detectors

none3We report on noise measurements performed on the n-side of double-sided, AC-coupled, punch-through biased silicon strip detectors. The noise has been measured over a wide range of peaking times and bias voltages, allowing the disentanglement of two excess noise terms, one related to the p-stops surrounding the strips and the other related to the electron accumulation layer at the Si/SiO2 interface.G. Giacomini; L. Bosisio; I. RashevskayaGiacomini, Gabriele; L., Bosisio; Rachevskaia, Irin

Noise Characterization of Double-Sided Silicon Microstrip Detectors With Punch-Through Biasing

none4We report on extensive noise measurements performed on double-sided, AC-coupled, punch-through biased silicon strip detectors. We used a single-channel acquisition chain, reading one strip per side, all other strips being kept grounded. The noise has been measured over a wide range of peaking times and leakage currents, allowing a careful determination of the various noise contributions. We determined the noise contribution of the punch-through mechanism and we observed, on different sensors, two unexpected noise terms, one related to the punch-through current and the other to the presence of resistive layers at the Si/SiO2 interface.G. Giacomini; L. Bosisio; I. Rashevskaya; O. StarodubtsevGiacomini, Gabriele; L., Bosisio; I., Rashevskaya; O., Starodubtse

A Comparative Evaluation of Integrated Capacitors for AC-Coupled Microstrip Detectors

The electrical reliability of integrated capacitors to be used for AC-coupled microstrip detectors has been investigated by characterizing a specially designed test chip. Capacitors employing different stacked dielectrics, including double-layer oxide, oxide-nitride, and oxide-nitride-oxide insulators, have been compared in terms of intrinsic breakdown field and extrinsic failures distribution. Results obtained from two fabrication runs are presented and discussed. The impact of the different technological options adopted on diode leakage current and bulk- and surface-generation parameters is also reporte

Study of frequency-dependent strip admittance in silicon microstrip detectors

We report on detailed interstrip admittance measurements performed on double-sided, AC-coupled and punch-through biased silicon microstrip detectors. The sensors chosen have been fabricated on very high resistivity substrates, which translates in very low depletion voltages, in the range 10–20 V. This, together with the absence of bias resistors, allows a careful study of the strip admittance components over a wide range of bias voltages and frequencies. In some instances, beyond total depletion the measured interstrip capacitance and dissipation factor exhibit a marked voltage and frequency dependence, linked to the presence of some resistive component. A simple lumped electrical model has been developed to explain the observed features and 3-D numerical simulations have been performed, supporting the interpretation of the phenomena. These features of the admittance have been found to be closely correlated with a non-standard noise term, exhibiting a peculiar frequency/time dependence, which adds in quadrature to the well known parallel and series noise sources