Precisely characterizing a radiation environment is essential for space exploration---manned and unmanned missions to, for example, the Moon or Mars---and astroparticle-physics experiments---for example, solar observations and cosmic-ray measurements. Particle detectors used for such endeavors must be compact, use as little power as possible, and withstand the harsh space environment. We are...
As particle physics strives for increased precision and sensitivity in its measurements, the beam energy, power, and per-bunch luminosity of colliders increase and produce significantly more complex events primarily by way of overlapping collisions (pileup) that test the performance and robustness of our algorithms and analysis.
One avenue towards mitigating the effects of pileup in tracking...
Timepix3 detectors are the latest generetion of hybrid active pixel detectors of the Medipix family. Such detectors consist of an active sensor layer wich is flip-chip bump-bonded the readout ASIC, segmenting the detector into a square matrix of 256 x 256 pixels (pixel pitch 55 µm). Ionizing radiation interacting in the active sensor material creates charge carriers, which drift towards the...
Tipsy is an assembly of a pixel chip and a stack of transmission dynodes "tynodes", placed in the vacuum under a classical window+photocathode. A tynode is an array of thin membranes: an electron impinging the upper surface causes the emission of (now) 5.5 secondary electrons at the bottom side. A stack of 5 tynodes causes a cloud of 5.5**5 = 5 k electrons to enter the pixel input pad,...
Over the last years, wireless data transmission technologies have seen tremendous progress to cope with the ever increasing demand on bandwidth, for instance in the mobile sector. Developments on short distance communication are pushing towards frequencies in the mm-band which allow the use of an even higher bandwidth and smaller form factors.
In high energy physics the demand on bandwidth...
Monolithic pixel sensors based on commercial CMOS processes offer many features which are important for track trigger applications. Most relevant are the smaller pixel sizes at reduced material and the lower production costs. Industrially produced monolithic pixel sensors are significantly cheaper than standard semiconductor trackers, thus allowing to instrument large areas of tracking...
There is an increasing demand for precision time measurement in particle physics experiments, to reject pile-up as efficiently as possible. This translates into projects of precision timing tracker/preshower detectors at LHC experiments, in the frame of high luminosity upgrades (Phase 2 HL-LHC). There is little doubt that these techniques, if they can be used successfully at HL-LHC, will enter...
The readout rates required for the next generation pixel detectors to be used in the ATLAS and CMS experiments at the High-Luminosity LHC (HL-LHC) will be about 3 Gb/s/cm2. The very high radiation levels and small space available makes it impossible to envisage optical conversion on chip, which should be done using electrical links, implying that a significant material contribution will be...
This paper describes the reconstruction of trajectories form charged particles (tracks) inside a generic tracker considering tracks as functional data and including particle properties. First the clusters are broadly grouped in regions of phase space to break down the pattern recognition problem into groups of tracks which point into similar directions. Curves are then interpolated from...
The ATLAS experiment at the high-luminosity LHC will face a five-fold increase in the number of interactions per collision relative to the ongoing Run 2. This will require a proportional improvement in rejection power at the earliest levels of the detector trigger system, while preserving good signal efficiency. One critical aspect of this improvement will be the implementation of precise...
"A new tracking detector is under development for the Compact Muon Solenoid (CMS) experiment at the High-Luminosity LHC (HL-LHC). It includes an outer tracker that will construct stubs, built from clusters reconstructed in two closely-spaced layers, for the rejection of hits from low transverse momentum tracks and transmit them off-detector at 40MHz. If tracker data is to contribute to keeping...
The increase of luminosity at HL-LHC will require the introduction of tracker information at Level-1 trigger system in CMS to maintain an acceptable trigger rate to select interesting events despite the one order of magnitude increase in the minimum bias interactions. To extract in the required latency the track information a dedicated hardware has to be used. We present the tests of a...
The High Luminosity LHC (HL-LHC) is expected to deliver luminosities of $5\times10ˆ{34} ~\mathrm{cm}ˆ2/\mathrm{s}$, with an average of about 140 overlapping proton-proton collisions per bunch crossing. These extreme pileup conditions place stringent requirements on the trigger system to be able to cope with the resulting event rates. A key component of the CMS upgrade for HL-LHC is a track...
For the ATLAS Fast TracKer (FTK) hardware-based track reconstruction
system, the AM chip is used in the pattern recognition step. The
version of the AM chip used in the FTK is based on eight associative
memory cells per pattern, corresponding to eight detector planes. Patterns
are identified for addresses where seven out of the eight memory cells
indicate a matching hit. The associative...
The Belle II detector is currently being built in Tsukuba, Japan and
will record $e^+e^-$ collision events at a record-breaking instantaneous
luminosity of $8\cdot 10^{35} \ \mathrm{cm^{-2}s^{-1}}$ which is delivered
by the SuperKEKB collider. Such a large luminosity is required to significantly
improve the precision on measurements of $B$, $D$ and $\tau$ decays to probe
for signs of physics...
The new Belle II experiment at the asymmetric $e^+e^-$ accelerator SuperKEKB at KEK in Japan is designed to deliver a highest instantaneous luminosity of $8 \times 10^{35} \text{cm}^{-2} \text{s}^{-1}$. To perform high-precision track reconstruction, e.g. for measurements of time dependent CPV decays and secondary vertices, the Belle II detector is equipped with a DEPFET pixel detector (PXD)...
The significant instantaneous luminosity planned at the High-Luminosity LHC will present a challenging environment for online track reconstruction.
Hardware acceleration of tracking algorithms on parallel architectures is an attractive solution to meeting latency restrictions in online systems.
Here we present an FPGA implementation of the Kalman Filter for fitting and cleaning tracks.
The...
Due to an enormous collision rate, charge information from particles traversing the innermost layers of the upgraded ATLAS and CMS detectors will be discretized using the time over threshold (ToT) method. Clever data manipulation, compression, or augmentation schemes can make a significant impact on downstream pattern recognition algorithms. In the context of the high-luminosity LHC (HL-LHC)...
Scientific simulations or data acquisition processes often result in large amounts of data samples that need to be "connected" to allow people to understand the information/meaning hidden within. However, if we simply connect all related data points we may end up with an even larger dataset that is more difficult to understand. I will thus talk about illustrative forms of visualization that...
The characterization of molecule dynamics in living cells is of paramount interest in quantitative microscopy. This challenge is usually addressed in fluorescent video-microscopy from particle trajectories computed by tracking algorithms. However, classifying individual trajectories into three diffusion groups – subdiffusion, free diffusion (or Brownian motion) and superdiffusion – is a...
Tracking at the HL-LHC in ATLAS and CMS will be very challenging. In particular, the pattern recognition will be very resource hungry, as extrapolated from current conditions. There is a huge on-going effort to optimise the current software. In parallel, completely different approaches should be explored.
To reach out to Computer Science specialists, a Tracking Machine Learning challenge...
To participate to this hackathon, it is necessary to register using the "hackathon registration" button on the left hand side menu.
See the motivation for an HL-LHC tracking challenge in the previous talk abstract. A RAMP (Rapid Analysis and Model Prototyping) on the Paris-Saclay platform is a mini-challenge/hackathon. Simulated LHC like events in 2D will be proposed, simplified but not too...
Run-2 of the LHC has provided new challenges to track and vertex reconstruction with higher centre-of-mass energies and luminosity leading to increasingly high-multiplicity environments, boosted, and highly-collimated physics objects. In addition, the Insertable B-layer (IBL) is a fourth pixel layer, which has been inserted at the centre of ATLAS during the shutdown of the LHC. We will present...
The large data samples at the High-Luminosity LHC will enable precise measurements of the Higgs boson and other Standard Model particles, as well as searches for new phenomena such as supersymmetry and extra dimensions. To cope with the experimental challenges presented by the HL-LHC such as large radiation doses and high pileup, the current Inner Detector will be replaced with a new...
After 2020, CERN is planning an upgrade program of the LHC collider (HL-LHC) which will bring the luminosity up to 5x10^{34} cm^{−2}s^{−1}, almost five times the one foreseen for 2017, meaning a mean of more than 140 inelastic collisions superimposed on the event of interest. In this high-occupancy environment, reconstructing the particle momentum with high precision is one of the biggest...
The Mu3e experiment is designed to search for the lepton flavour
violating decay $\mu^+ \rightarrow e^+e^-e^+$.
The aim of the experiment is to reach a branching ratio sensitivity of $10^{-16}$.
At first phase the experiment will be performed at existing beam line
providing $10^8$ muons per second at the Paul-Scherrer Institute (Switzerland)
which will allow to reach sensitivity of...
The P2 experiment in Mainz (Germany) aims to determine the weak mixing angle at low momentum transfer with an unprecedented precision. The approach of P2 is to measure the parity‑violating asymmetry of elastic electron-proton scattering, from which the weak charge of the proton, and so the weak mixing angle can be evaluated.
In P2, an electron beam (150 µA, 155 MeV/c$^2$) of alternating...
The Conceptual Design Report study on a high energy Circular Electron Positron Collider as a Higgs and/or Z factory is in progress and the tracker research is one of important parts. Based on the design from the ILD using TPC, the study group study the performances on the flavor tag varied with the parameters of the tracker to optimize the tracker design. As parallel, a preliminary design of...
The Mu3e experiment searches for the lepton flavour violating decay $\mu^+ \rightarrow e^+e^-e^+$,
aiming at a branching ratio sensitivity better than $10^{-16}$. To reach this
sensitivity, muon rates above $10^9 \mu/s$ are required. A high precision silicon tracking detector combined with excellent timing resolution from
scintillating fibers and tiles will measure the momenta, vertices and...
SHiP is a new general purpose fixed target facility proposed at the CERN SPS accelerator to search for particles predicted by Hidden Portals. The SHiP detector consists of a spectrometer located downstream of a large decay volume. It contains a tracker whose purpose is to reconstruct charged particles from the decay of neutral New Physics objects with high efficiency, while rejecting...
Starting from 2019 the Large Hadron Collider will undergo upgrades in order to increase its luminosity.
Many of the algorithms executed during track reconstruction scale linearly with the pileup. Others, like seeding, due to the increasing combinatorics, will dominate the execution time, due to their factorial complexity with respect to the pileup.
We will show the results of the effort in...
Extrapolation of trajectories through a magnetic field is needed at various stages of pattern recognition or track fitting procedures, with more or less precision. The Runge-Kutta method implies many calls to a field function and it is generally time consuming. In practice the trajectories may be split in steps between a few predefined surfaces, with possible additional short segments to...
Present data taking conditions and further
upgrades of high energy particle colliders, as well as detector systems, call for new ideas. A novel combination of
established data analysis techniques for charged-particle reconstruction is
proposed. It uses all information available in a collision event while keeping
competing choices open as long as possible.
Suitable track candidates are...
A Time Projection Chamber (TPC) is foreseen as the main tracking detector for the International Large Detector (ILD) one of the two detectors for the next candidate collider named International Linear Collider (ILC).
GridPix, which is a combination of micro-pattern gaseous detector with a pixelised readout system, is one of the candidate readout systems for the TPC [1]. One of the challenges...
Belle II is a multipurpose detector which will be operated at the asymmetric B-Factory SuperKEKB (Japan). The unprecedented instantaneous luminosity of up to $8\times 10 ^{35} \text{cm}^{-2} \text{s}^{-1}$ provided by the accelerator together with the level 1 trigger rate in the range of $30 \text{kHz}$ will pose extreme requirements on the sub-detectors of Belle II and the track finding...
For over a decade now, physical and energy constraints have limited clock speed improvements in commodity microprocessors. Instead, chipmakers have been pushed into producing lower-power, multi-core processors such as GPGPU, ARM and Intel MIC. Broad-based efforts from manufacturers and developers have been devoted to making these processors user-friendly enough to perform general computations....
By 2020 the LHCb experiment will be upgraded to run at an, by a factor of 5, increased instantaneous luminosity of 2x10^33 cm^-2 s^-1. The hardware trigger will be removed and replaced by a fully software based stage. This will dramatically increase the rate of collisions the software trigger system has to process. Additionally, the increased luminosity will lead to a higher number of tracks...
In order to overcome the difficulty brought by the curling charged tracks in the BESIII drift chamber,
we introduce the Hough transform based tracking method. This method is used as the supplementary to find
low transverse momentum tracks. This tracking algorithm is realized in C++ in BOSS (BESIII offline software system) and the performance has been checked by both Monte Carlo data and real...
Machine learning techniques have been successfully utilized in data processing and analysis for decades.
Hand in hand with the "deep learning revolution", the importance of Neural Networks in this area is still growing.
One advantage of employing a Neural Network is that certain features do not have to be engineered manually but are constructed by representations of the network.
This can...
The track trigger is one of the main components of the Belle II first level trigger, taking input from the central drift chamber. It consists of several steps, first combining hits to track segments, followed by a 2D track finding in the transverse plane and finally a 3D track reconstruction. The results of the track trigger are the track multiplicity, the momentum vector of each track and the...
As machine learning algorithms become increasingly sophisticated to exploit subtle features of the data, they often become more dependent on simulations. This paper presents a new approach to classification called weak supervision in which class proportions are the only input into the machine learning algorithm. A simple and general regularization technique is used to solve this non-convex...
A Common Tracking Software (ACTS) is a project that attempts to preserve the highly performant track reconstruction code from the first LHC era and prepares the code and concept for long term maintainability and adaption to future architecture. It is based primarily on the ATLAS Common Tracking Software, but has been decoupled to be detector and framework agnostic. ACTS supports several...
Particle track reconstruction in dense environments such as the detectors of the HL-LHC is a challenging pattern recognition problem. Traditional tracking algorithms such as the combinatorial Kalman Filter have been used with great success in LHC experiments for years. However, these state-of-the-art techniques are inherently sequential and scale poorly with the expected increases in detector...
As High Energy Physics (HEP) experiments extend the range of attainable luminosities to produce more particle tracks per bunch crossing than ever before, reconstructing the tracks produced in detectors from such interactions becomes more challenging and new methods of computation and data-handling are being explored.
Additionally, understanding portability of HEP algorithms to future...
A novel b-jet identification algorithm is constructed with a Recurrent Neural Network (RNN) at the ATLAS Experiment. This talk presents the expected performance of the RNN based b-tagging in simulated $t \bar t$ and high $p_T$ $Z’ \rightarrow b \bar b$ events. The RNN based b-tagging processes properties of tracks associated to jets which are represented in sequences. In contrast to...
Neutrino experiments discussed in this talk represent a category of event reconstruction problems very distinct from the collider experiments. The two main differences are: i) the representation of data, in form of 2D, high resolution, image-like projections, and ii) the nature of neutrino interactions observed in the detectors, with their high diversity of topologies and undefined location of...
