538 research outputs found
Wire Bonding on 2S Modules of the Phase-2 CMS Detector
No full textThe LHC will be upgraded to the HL-LHC in the Long Shutdown 3 starting 2024. This upgrade will increase the collision rate and the overall number of colliding particles requiring high precision particle detectors which are able to cope with much higher radiation doses and numbers of particle interactions per bunch crossing. To fulfill these technical requirements the CMS detector will be upgraded in the so-called Phase-2 Upgrade. Among others the silicon tracking system will be completely replaced by a new system providing a higher acceptance, an improved granularity and the feature to include its tracking information into the level-1 trigger. The new outer-tracker will consist of so called 2S modules consisting of two strip sensors and PS modules with a macro-pixel sensor and a strip sensor. The electrical connection between the strip sensors and the front-end electronics is realized by thin aluminum wire bonds. In this thesis the process of wire bonding is introduced and its implementation in the 2S module series production is discussed. Therefor a procedure of parameter optimization is developed and applied on a 2S dummy module. Additionally, the protection of the wire bonds via glue encapsulation is presented and feasibility tests of three different encapsulant candidates are discussed
Assembly and Test of Prototype 2S Modules for the Phase-2 Upgrade of the CMS Outer Tracker
No full textWithin the scope of the High Luminosity LHC upgrade the CMS experiment will be upgraded because due to radiation damage many components cannot be used any longer and higher particle fluxes will raise the technical requirements. In addition to other detector components, the entire silicon strip tracker will be replaced. The new sub-detector will consist of so-called PS and 2S modules with a stacked pair of sensor layers each. This module design will enable the integration of tracking information into the Level-1 trigger of the CMS detector on hardware level.The Physics Institute IB and the Physics Institute IIIB of RWTH Aachen University committed to assemble and test up to one thousand 2S modules. In the course of this PhD thesis multiple prototype detector modules have been assembled and the assembly procedure has been tested and improved with the focus being placed on the wire bonding step. The bonding quality has been evaluated by analyzing the bond machine data. As a tool for the module series production, a user interface has been developed to identify weak bonds. For the reception test of Kapton strips, which are used as high voltage isolators in the module assembly, a test setup with a dedicated user interface has been created. In addition, the series production was prepared by performing a detailed estimation of the assembly time and the required storage capabilities.Prototype modules were also used to test procedures for identifying and repairing damages. The properties of close-to-final prototype modules have been measured at the Test Beam Facility DESY with an electron beam. The particle tracks of the beam telescope have been aligned to the hits on the tested modules and the data have been analyzed. The analysis includes a study of the detector's spacial resolution, the assembly precision and a detailed evaluation of the hit and stub efficiency at different locations of the sensors and under different incidence angles. The results of the beam test analysis are furthermore discussed in the context of the detector operation at the High Luminosity LHC
Assembly and test of prototype 2S modules for the phase-2 upgrade of the CMS outer tracker
No full textWithin the scope of the High Luminosity LHC upgrade the CMS experiment will be upgraded because due to radiation damage many components cannot be used any longer and higher particle fluxes will raise the technical requirements. In addition to other detector components, the entire silicon strip tracker will be replaced. The new sub-detector will consist of so-called PS and 2S modules with a stacked pair of sensor layers each. This module design will enable the integration of tracking information into the Level-1 trigger of the CMS detector on hardware level. The Physics Institute IB and the Physics Institute IIIB of RWTH Aachen University committed to assemble and test up to one thousand 2S modules. In the course of this PhD thesis multiple prototype detector modules have been assembled and the assembly procedure has been tested and improved with the focus being placed on the wire bonding step. The bonding quality has been evaluated by analyzing the bond machine data. As a tool for the module series production, a user interface has been developed to identify weak bonds. For the reception test of Kapton strips, which are used as high voltage isolators in the module assembly, a test setup with a dedicated user interface has been created. In addition, the series production was prepared by performing a detailed estimation of the assembly time and the required storage capabilities. Prototype modules were also used to test procedures for identifying and repairing damages. The properties of close-to-final prototype modules have been measured at the Test Beam Facility DESY with an electron beam. The particle tracks of the beam telescope have been aligned to the hits on the tested modules and the data have been analyzed. The analysis includes a study of the detector’s spacial resolution, the assembly precision and a detailed evaluation of the hit and stub efficiency at different locations of the sensors and under different incidence angles. The results of the beam test analysis are furthermore discussed in the context of the detector operation at the High Luminosity LHC
Zwischen Draufsicht und Aufsicht – Internet gestützte Ausbildungssupervision
No full textAusbildungssupervision ist heute in vielen sozialen und pädagogischen Studiengängen Bestandteil der Begleitung und Beratung in Praxisphasen des Studiums. Liegen die Praxisstellen in größerer Entfernung vom Studienort, ist der Kontakt über das Internet oft die einzige Möglichkeit, die Ausbildungssupervision zu verwirklichen. An der Kath. Hochschule NRW wurde eine solche Internet gestützte Ausbildungssupervision konzipiert, erprobt und evaluiert. Mit Hilfe des Internet konnten Beratungsanlässe von den Studierenden sichtbarer und transparenter kommuniziert werden und waren somit in ganz anderer Weise nachvollzieh- und bearbeitbar.(Orig.)Educational supervision is a part of the curricula of several bachelor and master programs in social sciences in Germany. It is used for counseling and monitoring while student’s internships. If these internships are located too far away from the university, the internet is most of the time the only way to realize educational supervision. The Catholic university of applied sciences in Cologne, Germany, invented and evaluated an internet based approach of educational supervision, which helps to visualize counseling causes and the work with it during the supervision process. (author
Investigation of New Technologies to Improve Light Collection from Scintillating Crystals for Fast Timing
No full textInorganic scintillating crystals have been very successful in a variety of applications, such as high energy physics, medical physics, home land security and others. Next to the energy information these detectors deliver, also their potential to achieve precise timing information has become of increasing importance. Already today, recent developments in time-of-flight detectors based on scintillating crystals have reached coincidence time resolutions as high as ∼100 ps FWHM for 20 mm long crystals. The goal of this thesis is to pave the road towards the 10 ps regime, to make high energy physics cope with the future extreme luminosity and ultrashort bunch crossing intervals (as low as 500 ps) at the next generation of colliding beam accelerators. It may also serve to make medical physics benefit from simpler reconstruction algorithms, leading to higher image resolution and shorter imaging time in, e.g., PET. To reach this ambitious goal, an interdisciplinary approach in the domain of photodetection in general is needed. Therefore, this work must go hand in hand with advancements in the fields of scintillators, photodetectors and ultrafast electronics. Among these, this thesis focuses on the fields of scintillators and light transport. One aspect investigated in this thesis, is light transport inside- and light extraction from the crystal, based on the knowledge of the photon propagation modes in the crystal. Owing to the fact that scintillation light is emitted isotropically, the high refractive index of the crystal makes light rays undergo multiple reflections at the crystal surfaces, preventing an efficient and fast light extraction. To overcome the time spread generated by this effect, which ultimately limits the time resolution, photonic crystals slabs applied at the scintillator readout face might be a promising method to improve light extraction at the crystal-photodetector interface. The work in this thesis starts with with a study on improving imaging quality of an existing, breast-dedicated, scanner by introducing photonic crystals on the readout surfaces of the existing large monolithic LYSO crystals, of order 50x50 mm2 , already in use in the device. For that purpose, the author, in collaboration with partners of the TurboPET project, developed production methods for photonic crystals that were then applied and tested on the large LYSO crystals for the purpose of selecting the best method for a new prototype of this PET scanner. The best results were obtained with a sol-gel lithography process, that has produced a pattern of TiO2 cones (RI=2.4) with a 1.17 times increase in light output and a 1.3 times increase in energy resolution (at the single-crystal level). In total 10 such large crystals were produced with this pattern, which then led to an average increase in light output by a factor of 1.16 and an average improvement in energy resolution by a factor of 1.3. Following their implementation in the existing PET scanner, phantom tests were run to evaluate the overall performance of the device. These tests showed that the modified PET scanner benefited from an increase in signal-to-noise ratio of only ∼6%, nonetheless a promising result taken the fact that this was a first attempt of improving an existing PET scanner. The second part of the thesis entailed a dedicated investigation of photonic crystals, applied to smaller crystals, to search for an improvement in light output and in addition an improvement in the timing behavior in terms of coincidence time resolution (CTR). The focal point was a comparison between two photonic patterns, one with TiO2 pillars (RI=2.4) and the other with polymer cones (RI=1.82), both in a square lattice and imprinted on 10 mm LYSO cubes. It turns out from this comparison that the polymer cone pattern is superior in both light output (x1.7 over unpatterned) and CTR (x1.5 over unpatterned) than the TiO2 pillar pattern (x1.5 and 1.2, respectively). Additional tests addressed the question how the classical methods of improving light output, i.e. wrapping and optical coupling of the crystals, would compare to the results obtained with the results derived from photonic patterning. The third subject investigated in this thesis is related to exploring intrinsically fast scintillation mechanisms. The reason for this is that the determining factor for the time resolution of a scintillator is the initial photon density upon gamma conversion in the crystal. To first approximation, this initial photon density is given by the light output of the crystal divided by its decay time. As such, a high light output and a short decay time are crucial ingredients for fast timing. To break the CTR bench mark of 58 ps FWHM, obtained with classical, 3 mm long, LSO:Ce:0.4%Ca crystals, BaF2 was chosen as a promising candidate owing to its sub-nanosecond scintillation process due to crossluminescence in this crystal. A true challenge coming from using cross-luminescence stems from the very short emission wavelengths, usually in the deep UV, like e.g. 210 nm and 195 nm in BaF2. This imposes significant constraints on the use of photodetectors, as well as optical coupling agents and reflective wrapping materials, to cope with this short wavelength region. This limits the choice of fast UV-sensitive SiPMs, and in the long run only two producers were found to manufacture adequate SiPMs, i.e. Fondazione Bruno Kessler (FBK) and Hamamatsu, albeit with still relatively low photon detection efficiencies of around 20%. Comparing the two different producers it was found that, while both deliver adequate results, FBK clearly outperforms the Hamamatsu devices. As to the BaF2 crystals themselves, two different producers for their manufacture were chosen: Epic and Proteus. Among the two tested candidates, Epic and Proteus, the Epic crystal delivered consistently better results owing to its higher transparency at the cross-luminescence wavelengths. In first instance, the CTR measurements were made with air-coupling only. As such, from the arguments above an Epic crystal in conjunction with a Hamamatsu device delivered a CTR of 98±5 ps FWHM. In the case of coupling the same crystal to an FBK device, a clearly superior CTR of 54±6 ps FWHM was reached. Further to this, different optical coupling agents were tested in an attempt to see if the already very promising air-coupling results could still be improved. After initial selection tests, only glycerine and Viscasil remained as promising candidates for an eventual improvement in the CTR. While the behaviour of the two coupling agents, in particular glycerine, in terms of their potential improvement in CTR, is still debatable, the best result obtained with BaF2 coupled to a FBK SiPM with glycerine sets a new record in CTR of 51±6 ps FWHM, despite the FBK’s significantly inferior photon detection efficiency in the deep UV. This thesis has shown that exploiting cross-luminescence in crystals like BaF2 is a promising road to further research in the domain of ultra-high time resolution with photons
Penicillin production in industrial strain Penicillium chrysogenum P2niaD18 is not dependent on the copy number of biosynthesis genes
No full textPenicillin production in industrial strain Penicillium chrysogenum P2niaD18 is not dependent on the copy number of biosynthesis genes
No full textAdditional file 1: of Penicillin production in industrial strain Penicillium chrysogenum P2niaD18 is not dependent on the copy number of biosynthesis genes
No full textFigure S1. Construction of pcbC null mutant. (TIF 953Â kb
Clinical utility of an endorectal MRI-guided prostate probe: preliminary examinations
No full textProstate cancer (PCa) is one of the most common cancer diseases in men in the western countries [1]. Besides the palpation, and the amount of prostate-specific-antigen’s (PSA) inside the blood, the current diagnostic imaging technologies are not appropriate. Early diagnosis defining the exact tumor location, spread and margins could make efficient targeted biopsies and image-guided surgery. A multimodal imaging technique containing a transmit-receive surface coil for anatomical MR imaging, a (S)PET detector module, consisting of silicon photomultipliers (SiPM), for functional imaging and an ultrasound (US) probe are placed as close as possible to the prostate designed as an endorectal tube to increase sensitivity and spatial resolution. All materials that are used are non-magnetic. Advantages of the SiPM are diversified, like non-sensitive to magnetic fields, higher gain (105–106) than standard avalanche photodiodes (APD), good timing properties and compactness. The PET detector should reach approximately 1mm3 spatial resolution together with 60ps FWHM Time-of-Flight resolution and a high efficiency to reduce scanning time and injected dose. A home-made transmit-receive coil surrounding the PET module improves signal-to-noise-ratio (SNR) with respect to standard coils will be present. The system will be used as a MRI-insert and be able to visualize anatomic and metabolic information together. The US-probe is guiding examination for correct overlapping of the multimodal images. This procedure will save time, costs and the need of co-registration. By combining all advantages of each system, it will necessarily update the non-invasive treatment of PCa. The system is adapted and tested to a 3 Tesla MR scanner called Trio A Tim system and Allegra system from the company Siemens healthcare with a larmor frequency of 123.2 MHz and an input of 50 Ω free from artifacts. First results on homogeneity of the transmit-receive coil will be presented. Preliminary measurements showing the proposed device is challenging but feasible
Clinical utility of an endorectal MRI-guided prostate probe: preliminary examinations
No full textAbstract
Prostate cancer (PCa) is one of the most common cancer diseases in men in the western countries [1]. Besides the palpation, and the amount of prostate-specific-antigen’s (PSA) inside the blood, the current diagnostic imaging technologies are not appropriate. Early diagnosis defining the exact tumor location, spread and margins could make efficient targeted biopsies and image-guided surgery. A multimodal imaging technique containing a transmit-receive surface coil for anatomical MR imaging, a (S)PET detector module, consisting of silicon photomultipliers (SiPM), for functional imaging and an ultrasound (US) probe are placed as close as possible to the prostate designed as an endorectal tube to increase sensitivity and spatial resolution. All materials that are used are non-magnetic. Advantages of the SiPM are diversified, like non-sensitive to magnetic fields, higher gain (105–106) than standard avalanche photodiodes (APD), good timing properties and compactness. The PET detector should reach approximately 1mm3 spatial resolution together with 60ps FWHM Time-of-Flight resolution and a high efficiency to reduce scanning time and injected dose. A home-made transmit-receive coil surrounding the PET module improves signal-to-noise-ratio (SNR) with respect to standard coils will be present. The system will be used as a MRI-insert and be able to visualize anatomic and metabolic information together. The US-probe is guiding examination for correct overlapping of the multimodal images. This procedure will save time, costs and the need of co-registration. By combining all advantages of each system, it will necessarily update the non-invasive treatment of PCa. The system is adapted and tested to a 3 Tesla MR scanner called Trio A Tim system and Allegra system from the company Siemens healthcare with a larmor frequency of 123.2 MHz and an input of 50 Ω free from artifacts. First results on homogeneity of the transmit-receive coil will be presented. Preliminary measurements showing the proposed device is challenging but feasible.</jats:p
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