This paper describes an interactive tool for analysis of data from the ATLAS experiment taking place at the world's highest energy particle collider at CERN. The tool, called HYPATIA/applet, enables ...students of various levels to become acquainted with particle physics and look for discoveries in a similar way to that of real research.
Recent activities, towards the goal of introducing High Energy Physics in the school class, are reviewed. The most efficient method is a half or a full day workshop where the students are introduced ...to one of the large LHC experiments, follow a “virtual visit” to the experiment’s Control Room and perform an interactive analysis of real data. Science cafes and visits to the CERN expositions are also very helpful, provided that the tours/discussions are led by an active scientist and/or a trained teacher. Several EU outreach projects provide databases rich with education scenaria and data analysis tools ready to be used by the teachers in order to bridge the gap between modern research and technology and school education.
With the luminosity upgrade of the LHC machine (SLHC, Super-LHC), the Muon system of the ATLAS experiment at CERN will also need a detector upgrade in the highest rapidity region. MAMMA, Muon ATLAS ...Micromegas Activity, is an ongoing R&D activity with the aim to develop large detectors based on the bulk-Micromegas technology for use in the ATLAS Muon Spectrometer. Micromegas is a good potential candidate for the construction of large muon chambers that combine trigger and tracking capability and can sustain high particle rates expected at the SLHC. A medium size Micromegas prototype, in scale 1:10 of the final chambers, has been built and evaluated in the laboratory and in beam tests at CERN. Results from the analysis of test-beam data are presented. The results indicate that large size Micromegas is a viable candidate for ATLAS Muon upgrade
Relative gain monitoring of the GlueX calorimeters Anassontzis, E.G.; Ioannou, P.; Kourkoumelis, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2014, Letnik:
738
Journal Article
Recenzirano
The relative gain of the photodetectors for the GlueX Barrel and Forward calorimeters will be monitored using modular LED driver systems. The BCAL system consists of a global controller that feeds ...power, bias voltage and trigger signals to 96 local controllers situated at the ends of the 48 BCAL modules, which drive 40 LEDs associated with the 40 light guides at the end of each module. The FCAL system consists also of a global controller, a local controller for each acrylic quadrant covering the face of the FCAL, and ten 4-LED pulser boards per local controller connected in a star configuration along the edges of the acrylic panes. The respective systems are currently being installed on the detectors and their tested performance is presented herein.
•Electromagnetic calorimeter relative gain monitoring.•LED-based pulser system using common triggering.•Robust, cost effective, redundant operation.•System will measure radiation damage in lead glass.
This article documents the muon reconstruction and identification efficiency obtained by the ATLAS experiment for 139
fb
-
1
of
pp
collision data at
s
=
13
TeV collected between 2015 and 2018 during ...Run 2 of the LHC. The increased instantaneous luminosity delivered by the LHC over this period required a reoptimisation of the criteria for the identification of prompt muons. Improved and newly developed algorithms were deployed to preserve high muon identification efficiency with a low misidentification rate and good momentum resolution. The availability of large samples of
Z
→
μ
μ
and
J
/
ψ
→
μ
μ
decays, and the minimisation of systematic uncertainties, allows the efficiencies of criteria for muon identification, primary vertex association, and isolation to be measured with an accuracy at the per-mille level in the bulk of the phase space, and up to the percent level in complex kinematic configurations. Excellent performance is achieved over a range of transverse momenta from 3 GeV to several hundred GeV, and across the full muon detector acceptance of
|
η
|
<
2.7
.
A search for the electroweak production of charginos and sleptons decaying into final states with two electrons or muons is presented. The analysis is based on 139 fb−1 of proton–proton collisions ...recorded by the ATLAS detector at the Large Hadron Collider at s√=13 TeV. Three R-parity-conserving scenarios where the lightest neutralino is the lightest supersymmetric particle are considered: the production of chargino pairs with decays via either W bosons or sleptons, and the direct production of slepton pairs. The analysis is optimised for the first of these scenarios, but the results are also interpreted in the others. No significant deviations from the Standard Model expectations are observed and limits at 95% confidence level are set on the masses of relevant supersymmetric particles in each of the scenarios. For a massless lightest neutralino, masses up to 420 GeV are excluded for the production of the lightest-chargino pairs assuming W-boson-mediated decays and up to 1 TeV for slepton-mediated decays, whereas for slepton-pair production masses up to 700 GeV are excluded assuming three generations of mass-degenerate sleptons.
The algorithms used by the ATLAS Collaboration during Run 2 of the Large Hadron Collider to identify jets containing
b
-hadrons are presented. The performance of the algorithms is evaluated in the ...simulation and the efficiency with which these algorithms identify jets containing
b
-hadrons is measured in collision data. The measurement uses a likelihood-based method in a sample highly enriched in
t
t
¯
events. The topology of the
t
→
W
b
decays is exploited to simultaneously measure both the jet flavour composition of the sample and the efficiency in a transverse momentum range from 20 to 600 GeV. The efficiency measurement is subsequently compared with that predicted by the simulation. The data used in this measurement, corresponding to a total integrated luminosity of 80.5
fb
-
1
, were collected in proton–proton collisions during the years 2015–2017 at a centre-of-mass energy
s
=
13 TeV. By simultaneously extracting both the efficiency and jet flavour composition, this measurement significantly improves the precision compared to previous results, with uncertainties ranging from 1 to 8% depending on the jet transverse momentum.
Jet energy scale and resolution measurements with their associated uncertainties are reported for jets using 36–81 fb
-
1
of proton–proton collision data with a centre-of-mass energy of
s
=
13
TeV
...collected by the ATLAS detector at the LHC. Jets are reconstructed using two different input types: topo-clusters formed from energy deposits in calorimeter cells, as well as an algorithmic combination of charged-particle tracks with those topo-clusters, referred to as the ATLAS particle-flow reconstruction method. The anti-
k
t
jet algorithm with radius parameter
R
=
0.4
is the primary jet definition used for both jet types. This result presents new jet energy scale and resolution measurements in the high pile-up conditions of late LHC Run 2 as well as a full calibration of particle-flow jets in ATLAS. Jets are initially calibrated using a sequence of simulation-based corrections. Next, several in situ techniques are employed to correct for differences between data and simulation and to measure the resolution of jets. The systematic uncertainties in the jet energy scale for central jets (
|
η
|
<
1.2
) vary from 1% for a wide range of high-
p
T
jets (
250
<
p
T
<
2000
GeV
), to 5% at very low
p
T
(
20
GeV
) and 3.5% at very high
p
T
(
>
2.5
TeV
). The relative jet energy resolution is measured and ranges from (
24
±
1.5
)% at 20
GeV
to (
6
±
0.5
)% at 300
GeV
.
This article documents the performance of the ATLAS muon identification and reconstruction using the LHC dataset recorded at
s
=
13
TeV in 2015. Using a large sample of
J
/
ψ
→
μ
μ
and
Z
→
μ
μ
...decays from 3.2 fb
-
1
of
pp
collision data, measurements of the reconstruction efficiency, as well as of the momentum scale and resolution, are presented and compared to Monte Carlo simulations. The reconstruction efficiency is measured to be close to
99
%
over most of the covered phase space (
|
η
|
<
2.5
and
5
<
p
T
<
100
GeV). The isolation efficiency varies between 93 and
100
%
depending on the selection applied and on the momentum of the muon. Both efficiencies are well reproduced in simulation. In the central region of the detector, the momentum resolution is measured to be
1.7
%
(
2.3
%
) for muons from
J
/
ψ
→
μ
μ
(
Z
→
μ
μ
) decays, and the momentum scale is known with an uncertainty of
0.05
%
. In the region
|
η
|
>
2.2
, the
p
T
resolution for muons from
Z
→
μ
μ
decays is
2.9
%
while the precision of the momentum scale for low-
p
T
muons from
J
/
ψ
→
μ
μ
decays is about
0.2
%
.
The performance of identification algorithms (“taggers”) for hadronically decaying top quarks and
W
bosons in
pp
collisions at
s
= 13 TeV recorded by the ATLAS experiment at the Large Hadron Collider ...is presented. A set of techniques based on jet shape observables are studied to determine a set of optimal cut-based taggers for use in physics analyses. The studies are extended to assess the utility of combinations of substructure observables as a multivariate tagger using boosted decision trees or deep neural networks in comparison with taggers based on two-variable combinations. In addition, for highly boosted top-quark tagging, a deep neural network based on jet constituent inputs as well as a re-optimisation of the shower deconstruction technique is presented. The performance of these taggers is studied in data collected during 2015 and 2016 corresponding to 36.1 fb
-
1
for the
t
t
¯
and
γ
+
jet
and 36.7 fb
-
1
for the dijet event topologies.
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