The Timepix Telescope for high performance particle tracking Akiba, K.; Ronning, P.; van Beuzekom, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2013, Letnik:
723
Journal Article
Recenzirano
Odprti dostop
The Timepix particle tracking telescope has been developed as part of the LHCb VELO Upgrade project, supported by the Medipix Collaboration and the AIDA framework. It is a primary piece of ...infrastructure for the VELO Upgrade project and is being used for the development of new sensors and front end technologies for several upcoming LHC trackers and vertexing systems. The telescope is designed around the dual capability of the Timepix ASICs to provide information about either the deposited charge or the timing information from tracks traversing the 14×14mm matrix of 55×55μm pixels. The rate of reconstructed tracks available is optimised by taking advantage of the shutter driver readout architecture of the Timepix chip, operated with existing readout systems. Results of tests conducted in the SPS North Area beam facility at CERN show that the telescope typically provides reconstructed track rates during the beam spills of between 3.5 and 7.5kHz, depending on beam conditions. The tracks are time stamped with 1ns resolution with an efficiency of above 98% and provide a pointing resolution at the centre of the telescope of ∼1.6μm. By dropping the time stamping requirement the rate can be increased to ∼15kHz, at the expense of a small increase in background. The telescope infrastructure provides CO2 cooling and a flexible mechanical interface to the device under test, and has been used for a wide range of measurements during the 2011–2012 data taking campaigns.
•We provide a technical description of the Timepix Telescope for particle tracking applications.•We demonstrate the spatial and timing resolution to be 2μm and 1ns respectively.•The maximum particle rate is 7.5kHz with highly resolved timing and spacing.•The maximum particle rate is 15kHz with only highly resolved spacing.•We briefly describe the software and tracking algorithms used to achieve this.
The popularity of Machine Learning (ML) has been increasing in recent decades in almost every area, with the commercial and scientific fields being the most notorious ones. In particle physics, ML ...has been proven a useful resource to make the most of projects such as the Large Hadron Collider (LHC). The main advantage provided by ML is a reduction in the time and effort required for the measurements carried out by experiments, and improvements in the performance. With this work we aim to encourage scientists working with particle colliders to use ML and to try the different alternatives that are available, focusing on the separation of signal and background. We assess some of the most-used libraries in the field, such as Toolkit for Multivariate Data Analysis with ROOT, and also newer and more sophisticated options such as PyTorch and Keras. We also assess the suitability of some of the most common algorithms for signal-background discrimination, such as Boosted Decision Trees, and propose the use of others, namely Neural Networks. We compare the overall performance of different algorithms and libraries in simulated LHC data and produce some guidelines to help analysts deal with different situations. Examples include the use of low or high-level features from particle detectors or the amount of statistics that are available for training the algorithms. Our main conclusion is that the algorithms and libraries used more frequently at LHC collaborations might not always be those that provide the best results for the classification of signal candidates, and fully connected Neural Networks trained with Keras can improve the performance scores in most of the cases we formulate.
The LHCb VELO upgrade Dosil Suárez, Álvaro
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824
Journal Article
Recenzirano
The upgrade of the LHCb experiment, planned for 2019, will transform the experiment to a trigger-less system reading out the full detector at 40MHz event rate. All data reduction algorithms will be ...executed in a high-level software farm. The upgraded detector will run at luminosities of 2×1033cm−2s−1 and probe physics beyond the Standard Model in the heavy flavour sector with unprecedented precision. The Vertex Locator (VELO) is the silicon vertex detector surrounding the interaction region. The current detector will be replaced with a hybrid pixel system equipped with electronics capable of reading out at 40MHz. The detector comprises silicon pixel sensors with 55×55μm2 pitch, read out by the VeloPix ASIC, based on the TimePix/MediPix family. The hottest region will have pixel hit rates of 900Mhits/s yielding a total data rate more than 3Tbit/s for the upgraded VELO. The detector modules are located in a separate vacuum, separated from the beam vacuum by a thin custom made foil. The detector halves are retracted when the beams are injected and closed at stable beams, positioning the first sensitive pixel at 5.1mm from the beams. The material budget will be minimised by the use of evaporative CO2 coolant circulating in microchannels within 400μm thick silicon substrates.
While designed primarily for X-ray imaging applications, the Medipix3 ASIC can also be used for charged-particle tracking. In this work, results from a beam test at the CERN SPS with irradiated and ...non-irradiated sensors are presented and shown to be in agreement with simulation, demonstrating the suitability of the Medipix3 ASIC as a tool for characterising pixel sensors.
This paper presents the techniques used to monitor radiation damage in the LHCb Tracker Turicensis during the LHC Runs 1 and 2. Bulk leakage currents in the silicon sensors were monitored ...continuously, while the full depletion voltages of the sensors were estimated at regular intervals by performing dedicated scans of the charge collection efficiency as a function of the applied bias voltage. Predictions of the expected leakage currents and full depletion voltages are extracted from the simulated radiation profile, the luminosity delivered by the LHC, and the thermal history of the silicon sensors. Good agreement between measurements and predictions is found.
ABSTRACT Introduction Turpentine is an oleoresin obtained from various species of pine. It contains a volatile oil (oil of turpentine) which is responsible for its properties and this is the form ...generally used. Opportunity for contact with turpentine is widespread. It is universally used as a solvent to dissolve and thin lacquers, varnishes and paints. It is also an ingredient in many liniments and cold remedies. Turpentine is regarded as both a local irritant and a sensitizer. Cases of allergic contact dermatitis in painters, mechanics, shoe repairers and home decorators have been reported. Case report We report a case of a non-professional painter who developed a contact allergic dermatitis due to his exposure to turpentine while doing oil-painting as a hobby. Discussion Dermatitis is one of the biggest dangers of working with art materials and occupational contact dermatitis is often detected on the hands of the painters. Solvents are indispensable and turpentine is the most important and the traditional one used in oil-painting. Contact allergy to oil of turpentine was reported to have become rare in Europe but over the last few years, increased rates of turpentine sensitization have been reported.
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