78 research outputs found
Harnessing the Power of Multi-Task Pretraining for Ground-Truth Level Natural Language Explanations
Natural language explanations promise to offer intuitively understandable
explanations of a neural network's decision process in complex vision-language
tasks, as pursued in recent VL-NLE models. While current models offer
impressive performance on task accuracy and explanation plausibility, they
suffer from a range of issues: Some models feature a modular design where the
explanation generation module is poorly integrated with a separate module for
task-answer prediction, employ backbone models trained on limited sets of
tasks, or incorporate ad hoc solutions to increase performance on single
datasets. We propose to evade these limitations by applying recent advances in
large-scale multi-task pretraining of generative Transformer models to the
problem of VL-NLE tasks. Our approach outperforms recent models by a large
margin, with human annotators preferring the generated explanations over the
ground truth in two out of three evaluated datasets. As a novel challenge in
VL-NLE research, we propose the problem of multi-task VL-NLE and show that
jointly training on multiple tasks can increase the explanation quality. We
discuss the ethical implications of high-quality NLE generation and other
issues in recent VL-NLE research.Comment: Minor change
Pixel detector hybridisation with Anisotropic Conductive Films
Hybrid pixel detectors require a reliable and cost-effective interconnect
technology adapted to the pitch and die sizes of the respective applications.
During the ASIC and sensor R&D phase, and in general for small-scale
applications, such interconnect technologies need to be suitable for the
assembly of single-dies, typically available from Multi-Project-Wafer
submissions. Within the CERN EP R&D programme and the AIDAinnova collaboration,
innovative hybridisation concepts targeting vertex-detector applications at
future colliders are under development. This contribution presents recent
results of a newly developed in-house single-die interconnection process based
on Anisotropic Conductive Film (ACF). The ACF interconnect technology replaces
the solder bumps with conductive particles embedded in an adhesive film. The
electro-mechanical connection between the sensor and the read-out chip is
achieved via thermo-compression of the ACF using a flip-chip device bonder. A
specific pad topology is required to enable the connection via conductive
particles and create cavities into which excess epoxy can flow. This pixel-pad
topology is achieved with an in-house Electroless Nickel Immersion Gold (ENIG)
plating process that is also under development within the project. The ENIG and
ACF processes are qualified with the Timepix3 ASIC and sensors, with 55 um
pixel pitch and 14 um pad diameter. The ACF technology can also be used for
ASIC-PCB/FPC integration, replacing wire bonding or large-pitch solder bumping
techniques. This contribution introduces the ENIG plating and ACF processes and
presents recent results on Timepix3 hybrid assemblies
Test-beam Performance Results of the FASTPIX Sub-Nanosecond CMOS Pixel Sensor Demonstrator
Within the ATTRACT FASTPIX project, a monolithic pixel sensor demonstrator
chip has been developed in a modified 180 nm CMOS imaging process technology,
targeting sub-nanosecond timing precision for single ionising particles. It
features a small collection electrode design on a 25 micrometers-thick
epitaxial layer and contains 32 mini matrices of 68 hexagonal pixels each, with
pixel pitches ranging from 8.66 to 20 micrometers. Four pixels are transmitting
an analog output signal and 64 are transmitting binary hit information. Various
design variations are explored, aiming at accelerating the charge collection
and making the timing of the charge collection more uniform over the pixel
area. Signal treatment of the analog waveforms, as well as reconstruction of
digital position, time and charge information, is carried out off-chip. This
contribution introduces the design of the sensor and readout system and
presents performance results for various pixel designs achieved in recent test
beam measurements with external tracking and timing reference detectors. A time
resolution below 150 ps is obtained at full efficiency for all pixel pitches.Comment: 14 pages, 15 figures, submitted to NIMA (special issue for ULITIMA
2023 conference
Beam test results of silicon sensor module prototypes for the Phase-2 Upgrade of the CMS Outer Tracker
The start of the High-Luminosity LHC (HL-LHC) in 2027 requires upgrades to the Compact Muon Solenoid (CMS) Experiment. In the scope of the upgrade program the complete silicon tracking detector will be replaced. The new CMS Tracker will be equipped with silicon pixel detectors in the inner layers closest to the interaction point and silicon strip detectors in the outer layers. The new CMS Outer Tracker will consist of two different kinds of detector modules called PS and 2S modules. Each module will be made of two parallel silicon sensors (a macro-pixel sensor and a strip sensor for the PS modules and two strip sensors for the 2S modules). Combining the hit information of both sensor layers it is possible to estimate the transverse momentum of particles in the magnetic field of 3.8 T at the full bunch-crossing rate of 40 MHz directly on the module. This information will be used as an input for the first trigger stage of CMS.
It is necessary to validate the Outer Tracker module functionality before installing the modules in the CMS experiment. Besides laboratory-based tests several 2S module prototypes have been studied at test beam facilities at CERN, DESY and FNAL. This article concentrates on the beam tests at DESY during which the functionality of the module concept was investigated using the full final readout chain for the first time. Additionally the performance of a 2S module assembled with irradiated sensors was studied. By choosing an irradiation fluence expected for 2S modules at the end of HL-LHC operation, it was possible to investigate the particle detection efficiency and study the trigger capabilities of the module at the beginning and end of runtime of the CMS experiment.The start of the High-Luminosity LHC (HL-LHC) in 2027 requires upgrades to the Compact Muon Solenoid (CMS) experiment. In the scope of the upgrade program the complete silicon tracking detector will be replaced. The new CMS Tracker will be equipped with silicon pixel detectors in the inner layers closest to the interaction point and silicon strip detectors in the outer layers. The new CMS Outer Tracker will consist of two different kinds of detector modules called PS and 2S modules. Each module will be made of two parallel silicon sensors (a macro-pixel sensor and a strip sensor for the PS modules and two strip sensors for the 2S modules). Combining the hit information of both sensor layers, it is possible to estimate the transverse momentum of particles in the magnetic field of 3.8 T at the full bunch-crossing rate of 40 MHz directly on the module. This information will be used as an input for the first trigger stage of CMS. It is necessary to validate the Outer Tracker module functionality before installing the modules in the CMS experiment. Besides laboratory-based tests several 2S module prototypes have been studied at test beam facilities at CERN, DESY and FNAL. This article concentrates on the beam tests at DESY during which the functionality of the module concept was investigated using the full final readout chain for the first time. Additionally the performance of a 2S module assembled with irradiated sensors was studied. By choosing an irradiation fluence expected for 2S modules at the end of HL-LHC operation, it was possible to investigate the particle detection efficiency and study the trigger capabilities of the module at the beginning and end of the runtime of the CMS experiment
Synthesising knowledge for lean product development process of a low noise jet engine
The product development process is one of the most challenging stages of a product life cycle due to several reasons. Having the right knowledge environment during the design process may eliminate the waste of cost and time. The aim of this paper is to demonstrate a case study where designers can investigate the conflicting parameters about a product and make their decisions based on an accurate knowledge environment that is created by trade-off curves. The product in consideration is a turbofan jet engine with a requirement of noise reduction during takeoff while keeping up with high quality standards
Transient Monte Carlo Simulations for the Optimisation and Characterisation of Monolithic Silicon Sensors
An ever-increasing demand for high-performance silicon sensors requires
complex sensor designs that are challenging to simulate and model. The
combination of electrostatic finite element simulations with a transient Monte
Carlo approach provides simultaneous access to precise sensor modelling and
high statistics. The high simulation statistics enable the inclusion of Landau
fluctuations and production of secondary particles, which offers a realistic
simulation scenario. The transient simulation approach is an important tool to
achieve an accurate time-resolved description of the sensor, which is crucial
in the face of novel detector prototypes with increasingly precise timing
capabilities. The simulated time resolution as a function of operating
parameters as well as the full transient pulse can be monitored and assessed,
which offers a new perspective on the optimisation and characterisation of
silicon sensors.
In this paper, a combination of electrostatic finite-element simulations
using 3D TCAD and transient Monte Carlo simulations with the Allpix Squared
framework are presented for a monolithic CMOS pixel sensor with a small
collection diode, that is characterised by a highly inhomogeneous, complex
electric field. The results are compared to transient 3D TCAD simulations that
offer a precise simulation of the transient behaviour but long computation
times. Additionally, the simulations are benchmarked against test-beam data and
good agreement is found for the performance parameters over a wide range of
different operation conditions
Developing a Monolithic Silicon Sensor in a 65 nm CMOS Imaging Technology for Future Lepton Collider Vertex Detectors
Monolithic CMOS sensors in a 65 nm imaging technology are being investigated
by the CERN EP Strategic R&D Programme on Technologies for Future Experiments
for an application in particle physics. The appeal of monolithic detectors lies
in the fact that both sensor volume and readout electronics are integrated in
the same silicon wafer, providing a reduction in production effort, costs and
scattering material. The Tangerine Project WP1 at DESY participates in the
Strategic R&D Programme and is focused on the development of a monolithic
active pixel sensor with a time and spatial resolution compatible with the
requirements for a future lepton collider vertex detector. By fulfilling these
requirements, the Tangerine detector is suitable as well to be used as
telescope planes for the DESY-II Test Beam facility. The project comprises all
aspects of sensor development, from the electronics engineering and the sensor
design using simulations, to laboratory and test beam investigations of
prototypes. Generic TCAD Device and Monte-Carlo simulations are used to
establish an understanding of the technology and provide important insight into
performance parameters of the sensor. Testing prototypes in laboratory and test
beam facilities allows for the characterization of their response to different
conditions. By combining results from all these studies it is possible to
optimize the sensor layout. This contribution presents results from generic
TCAD and Monte-Carlo simulations, and measurements performed with test chips of
the first sensor submission.Comment: 7 pages, 8 figures, submitted to IEEE Xplore as conference record for
2022 IEEE NSS/MIC/RTS
Digital Pixel Test Structures implemented in a 65 nm CMOS process
The ALICE ITS3 (Inner Tracking System 3) upgrade project and the CERN EP R&D
on monolithic pixel sensors are investigating the feasibility of the Tower
Partners Semiconductor Co. 65 nm process for use in the next generation of
vertex detectors. The ITS3 aims to employ wafer-scale Monolithic Active Pixel
Sensors thinned down to 20 to 40 um and bent to form truly cylindrical half
barrels. Among the first critical steps towards the realisation of this
detector is to validate the sensor technology through extensive
characterisation both in the laboratory and with in-beam measurements. The
Digital Pixel Test Structure (DPTS) is one of the prototypes produced in the
first sensor submission in this technology and has undergone a systematic
measurement campaign whose details are presented in this article.
The results confirm the goals of detection efficiency and non-ionising and
ionising radiation hardness up to the expected levels for ALICE ITS3 and also
demonstrate operation at +20 C and a detection efficiency of 99% for a DPTS
irradiated with a dose of 1 MeV ncm.
Furthermore, spatial, timing and energy resolutions were measured at various
settings and irradiation levels.Comment: Updated threshold calibration method. Implemented colorblind friendly
color palette in all figures. Updated reference
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