Development and Test of a High Performance Multi Channel Readout System on a Chip with Application in PET/MR

The availability of new, compact, magnetic field tolerant sensors suitable for PET has opened the opportunity to build highly integrated PET scanners that can be included in commercial MR scanners. This combination has long been expected to have big advantages over existing systems combining PET and CT. This thesis describes my work towards building a highly integrated readout ASIC for application in PET/MR within the framework of the HYPERImage and SUBLIMA projects. It also gives a brief introduction into both PET and MR to understand the unique challenges for the readout system caused by each system, and their combination. A number of typical solutions for different requirements of the ASIC - timing measurements, trigger generation, and energy readout - and contemporary readout systems are presented to put our system in context. Detailed measurements have been performed to evaluate the performance of the ASIC, and the setup and results are presented here

Advanced Stirling Duplex Materials Assessment for Potential Venus Mission Heater Head Application

This report will address materials selection for components in a proposed Venus lander system. The lander would use active refrigeration to allow Space Science instrumentation to survive the extreme environment that exists on the surface of Venus. The refrigeration system would be powered by a Stirling engine-based system and is termed the Advanced Stirling Duplex (ASD) concept. Stirling engine power conversion in its simplest definition converts heat from radioactive decay into electricity. Detailed design decisions will require iterations between component geometries, materials selection, system output, and tolerable risk. This study reviews potential component requirements against known materials performance. A lower risk, evolutionary advance in heater head materials could be offered by nickel-base superalloy single crystals, with expected capability of approximately 1100C. However, the high temperature requirements of the Venus mission may force the selection of ceramics or refractory metals, which are more developmental in nature and may not have a well-developed database or a mature supporting technology base such as fabrication and joining methods

Thermomechanical and bithermal fatigue behavior of cast B1900 + Hf and wrought Haynes 188

High temperature thermomechanical and bithermal fatigue behavior was investigated for two superalloys: cast nickel-base B1900+Hf and wrought cobalt-base Haynes 188. Experimental results were generated to support development of an advanced thermal fatigue life prediction method. Strain controlled thermomechanical and load-controlled, strain-limited, bithermal fatigue tests were used to determine the fatigue crack initiation and cyclic stress-strain response characteristics of superalloys. Bithermal temperatures of 483 and 871 C were used for B1900+Hf, and 316 and 760 C for Haynes 188. Thermomechanical fatigue tests were conducted by using maximum and minimum temperatures corresponding to those for the bithermal experiments. Lives cover the range from about 10 to 3000 cycles to failure. Isothermal fatigue results obtained previously are also discussed

Oscillatory Structural Forces Across Dispersions of Micelles With Variable Surface Charge

When two surfaces interact across colloidal dispersions, oscillatory structural forces often arise due to an ordering of colloidal particles. Although this type of forces was intensively studied, the effect of the surface charge of the colloidal particles is still poorly understood. In the present study, the surface charge of colloidal particles is varied by changing the ratio of nonionic (Tween20) and anionic (sodium dodecyl sulfate, SDS) surfactants of micellar dispersions. The same micellar systems were previously characterised with small-angle neutron scattering (SANS) by the authors, revealing that mixed nonionic-anionic surfactant micelles with variable surface charge form. The present paper addresses the ordering phenomena of the micellar systems under confinement. Therefore, forces across these dispersions were measured for varying surface charges and volume fractions of the micelles, using colloidal-probe atomic force microscopy (CP-AFM). The combination of SANS and CP-AFM experiments allows the dispersions structure in bulk and under geometrical confinement to be compared in terms of the characteristic interparticle distance, correlation length, and ordering strength: In bulk and under confinement, the characteristic intermicellar distance increases by introducing surface charges to micelles until the electrostatic repulsion forces the micelles into a specific ordering. There, the characteristic intermicellar distance purely relates to the micelle volume fraction ϕ as ∝ ϕ−1/3. While in dispersions of uncharged micelles the characteristic intermicellar distance is reduced from bulk to confinement, no such compressibility is observed once the micelles are charged. Furthermore, variation of the micelles surface charge has only little effect on the correlation length of the micelles ordering which is mainly governed by hard-sphere interactions, especially in concentrated dispersions. Introducing surface charges, however, enhances the ordering strength (i.e., the amplitude) of oscillatory structural forces due to stronger electrostatic repulsions of the micelles with the equally charged confining surface. This surface-induced effect is not represented in bulk scattering experiments

Probing the potential of CdZnTe for high-energy high-flux 2D X-ray detection using the XIDer incremental digital integrating readout

The latest synchrotron radiation sources have the capability to produce X-ray beams with a photon flux that can be up to three orders of magnitude higher than previous-generation facilities, and that are not manageable by the currently available 2D photon-counting pixel detectors. The construction of new detectors that exceed the limitations of existing devices is a critical strategic need. Developing such detectors is a challenge in terms of readout electronics as well as sensor material, particularly in the case of devices intended to operate at X-ray energies above 30 keV. The approach adopted at the ESRF to deal with this major difficulty is twofold: the use of a novel semiconductor material with improved electrical properties, high-flux CdZnTe, and the investigation of a specific readout scheme, incremental digital integration, via the XIDer project in collaboration with the University of Heidelberg. Incremental digital integration is a method intended to be less sensitive to variations of the dark current than the conventional charge integration readout. However, this readout scheme requires that the leakage current from the sensor material stays below a certain threshold to reduce the leakage contributions. This paper introduces the ESRF strategy and few examples of the methods employed to evaluate the performance and leakage current behavior of high-flux CdZnTe pixelated sensors. These examples illustrate the first results obtained with this material under moderate to very high X-ray irradiation fluxes of up to 1012 photons/mm2/s

Status of the BELLE II Pixel Detector

The Belle II experiment at the super KEK B-factory (SuperKEKB) in Tsukuba, Japan, has been collecting $e^+e^−$ collision data since March 2019. Operating at a record-breaking luminosity of up to $4.7×10^{34} cm^{−2}s^{−1}$, data corresponding to $424 fb^{−1}$ has since been recorded. The Belle II VerteX Detector (VXD) is central to the Belle II detector and its physics program and plays a crucial role in reconstructing precise primary and decay vertices. It consists of the outer 4-layer Silicon Vertex Detector (SVD) using double sided silicon strips and the inner two-layer PiXel Detector (PXD) based on the Depleted P-channel Field Effect Transistor (DePFET) technology. The PXD DePFET structure combines signal generation and amplification within pixels with a minimum pitch of $(50×55) μm^2$. A high gain and a high signal-to-noise ratio allow thinning the pixels to $75 μm$ while retaining a high pixel hit efficiency of about $99$. As a consequence, also the material budget of the full detector is kept low at $≈0.21$$\frac{X}{X_0}$ per layer in the acceptance region. This also includes contributions from the control, Analog-to-Digital Converter (ADC), and data processing Application Specific Integrated Circuits (ASICs) as well as from cooling and support structures. This article will present the experience gained from four years of operating PXD; the first full scale detector employing the DePFET technology in High Energy Physics. Overall, the PXD has met the expectations. Operating in the intense SuperKEKB environment poses many challenges that will also be discussed. The current PXD system remains incomplete with only 20 out of 40 modules having been installed. A full replacement has been constructed and is currently in its final testing stage before it will be installed into Belle II during the ongoing long shutdown that will last throughout 2023

Search for Axionlike Particles Produced in e⁺ e⁻ Collisions at Belle II

International audienceWe present a search for the direct production of a light pseudoscalar a decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process e+e-→γa, a→γγ in the mass range 0.2

UNICOS framework and EPICS: A possible integration

UNICOS (UNified Industrial Control System) is a CERN-made framework to develop industrial control applications. It follows a methodology based on ISA-88 and provides components in two layers of a control system: control and supervision. The control logic is running in the first layer, in a PLC (Programmable Logic Controller), and, in the second layer, a SCADA (Supervisory Control and Data Acquisition) system is used to interface with the operators and numerous other features (e.g. alarms, archiving, etc.). UNICOS supports SIEMENS WinCC OA as the SCADA system. In this paper, we propose to use EPICS (Experimental Physics and Industrial Control System) as the supervision component of the UNICOS framework. The use case is the control system of a CO$_{2}$ cooling plant developed at CERN following the UNICOS methodology, which had to be integrated in a control system based on EPICS. The paper describes the methods and actions taken to make this integration feasible, including automatic EPICS database generation, PLC communications, visualization widgets, faceplates and synoptics and their integration into CSS and EPICS, as well as the integration with the BEAST alarm system

Performance of FBK SiPMs coupled to PETA3 read-out ASIC for PET application

In this paper we show the energy and timing resolution performances of FBK SiPMs coupled to the PETA3 ASIC for PET application. We developed a measurement set-up to characterize single SiPMs coupled to scintillator exploiting the detector stack developed within the HYPERImage project. In this way we are able to characterize the combined SiPM/ASIC performance with the same signal chain (from the sensor to the ASIC board) used in the PET system. We show that using two scintillator detectors, composed of a 3x3x5mm^3 LYSO crystal coupled to a 3x3mm^2 SiPM, an intra-stack CRT of about 200ps FWHM can be obtained