The high-level trigger of ALICE Tilsner, H.; Alt, T.; Aurbakken, K. ...
The European physical journal. C, Particles and fields,
07/2004, Letnik:
33, Številka:
S1
Journal Article
Recenzirano
Odprti dostop
AbstractOne of the main tracking detectors of the forthcoming ALICE Experiment at the LHC is a cylindrical Time Projection Chamber (TPC) with an expected data volume of about 75 MByte per event. This ...data volume, in combination with the presumed maximum bandwidth of 1.2 GByte/s to the mass storage system, would limit the maximum event rate to 20 Hz. In order to achieve higher event rates, online data processing has to be applied. This implies either the detection and read-out of only those events which contain interesting physical signatures or an efficient compression of the data by modeling techniques. In order to cope with the anticipated data rate, massive parallel computing power is required. It will be provided in form of a clustered farm of SMP-nodes, based on off-the-shelf PCs, which are connected with a high bandwidth low overhead network. This High-Level Trigger (HLT) will be able to process a data rate of 25 GByte/s online. The front-end electronics of the individual sub-detectors is connected to the HLT via an optical link and a custom PCI card which is mounted in the clustered PCs. The PCI card is equipped with an FPGA necessary for the implementation of the PCI-bus protocol. Therefore, this FPGA can also be used to assist the host processor with first-level processing. The first-level processing done on the FPGA includes conventional cluster-finding for low multiplicity events and local track finding based on the Hough Transformation of the raw data for high multiplicity events.PACS: 07.05.-t Computers in experimental physics – 07.05.Hd Data acquisition: hardware and software – 29.85.+c Computer data analysis
Online pattern recognition for the ALICE high level trigger Bramm, R.; Helstrup, H.; Lien, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2003, Letnik:
502, Številka:
2
Journal Article
Recenzirano
The ALICE High Level Trigger system needs to reconstruct events online at high data rates. Focusing on the Time Projection Chamber we present two pattern recognition methods under investigation: the ...sequential approach (cluster finding, track follower) and the iterative approach (Hough Transform, cluster assignment, re-fitting). The implementation of the former in hardware indicates that we can reach the designed inspection rate for p–p collisions of
1
kHz
with 98% efficiency.
High-level trigger system for the LHC ALICE experiment Bramm, R.; Helstrup, H.; Lien, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2003, Letnik:
502, Številka:
2
Journal Article
Recenzirano
The central detectors of the ALICE experiment at LHC will produce a data size of up to
75
MB/
event
at an event rate
⩽200
Hz
resulting in a data rate of
∼15
GB/
s
. Online processing of the data is ...necessary in order to select interesting (sub)events (“High Level Trigger”), or to compress data efficiently by modeling techniques. Processing this data requires a massive parallel computing system (High Level Trigger System). The system will consist of a farm of clustered SMP-nodes based on off-the-shelf PCs connected with a high bandwidth low latency network.
Strange and multistrange baryon production is expected to be enhanced in heavy ion interactions if a phase transition from hadronic matter to a Quark-Gluon Plasma takes place. The production yields ...of
Λs,
Λ
s,
Ξ
−s, and
Ξ
+
s relative to the production of negative particles are presented for sulphur-tungsten interactions at 200 GeV/
c per nucleon. These production yields are compared to those produced in proton-tungsten interactions and the enhancements of strange and multistrange baryons and antibaryons are presented.
The ALICE detector is a dedicated heavy-ion detector at the large hadron collider which is commissioned end of 2007 at CERN. The ALICE triggers are handled by the central trigger processor and ...distributed to all sub-detectors, amongst other the time projection chamber and the photon spectrometer. The front end electronics of the time projection chamber and the photon spectrometer share many of the same components. The photon spectrometer provides the trigger system with level 0 and level 1 triggers (e.g., high-P t photons) by the use of several trigger router units and a trigger-OR board. The trigger electronics and the front end electronics are situated close to the collision-point, and errors due to radiation effects are to be expected. This article gives an overview of the trigger system from trigger generation with the photon spectrometer to trigger reception of the front end electronics of both detectors. How to deal with the possible effects of the radiation environment on the electronics that do trigger handling was evaluated.
Strange and multistrange baryon and antibaryon production is a useful probe into the dynamics of the hot hadronic matter created in central heavy ion interactions. Relative production yields and ...transverse mass spectra are presented for Λ,
Λ
, Ξ
− and
Ξ
+ hyperons produced in central sulphur-tungsten interactions at 200 GeV/
c per nucleon.
We present the performance of a full-length prototype of the ALICE Forward Calorimeter (FoCal). The detector is composed of a silicon-tungsten electromagnetic sampling calorimeter with longitudinal ...and transverse segmentation (FoCal-E) of about 20\(X_0\) and a hadronic copper-scintillating-fiber calorimeter (FoCal-H) of about 5\(\lambda_{\rm int}\). The data were taken between 2021 and 2023 at the CERN PS and SPS beam lines with hadron (electron) beams up to energies of 350 (300) GeV. Regarding FoCal-E, we report a comprehensive analysis of its response to minimum ionizing particles across all pad layers. The longitudinal shower profile of electromagnetic showers is measured with a layer-wise segmentation of 1\(X_0\). As a projection to the performance of the final detector in electromagnetic showers, we demonstrate linearity in the full energy range, and show that the energy resolution fulfills the requirements for the physics needs. Additionally, the performance to separate two-showers events was studied by quantifying the transverse shower width. Regarding FoCal-H, we report a detailed analysis of the response to hadron beams between 60 and 350 GeV. The results are compared to simulations obtained with a Geant4 model of the test beam setup, which in particular for FoCal-E are in good agreement with the data. The energy resolution of FoCal-E was found to be lower than 3% at energies larger than 100 GeV. The response of FoCal-H to hadron beams was found to be linear, albeit with a significant intercept that is about factor 2 larger than in simulations. Its resolution, which is non-Gaussian and generally larger than in simulations, was quantified using the FWHM, and decreases from about 16% at 100 GeV to about 11% at 350 GeV. The discrepancy to simulations, which is particularly evident at low hadron energies, needs to be further investigated.
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