The ATLAS experiment at the Large Hadron Collider employs a two-level trigger system to record data at an average rate of 1 kHz from physics collisions, starting from an initial bunch crossing rate ...of 40 MHz. During the LHC Run 2 (2015–2018), the ATLAS trigger system operated successfully with excellent performance and flexibility by adapting to the various run conditions encountered and has been vital for the ATLAS Run-2 physics programme. For proton-proton running, approximately 1500 individual event selections were included in a trigger menu which specified the physics signatures and selection algorithms used for the data-taking, and the allocated event rate and bandwidth. The trigger menu must reflect the physics goals for a given data collection period, taking into account the instantaneous luminosity of the LHC and limitations from the ATLAS detector readout, online processing farm, and offline storage. This document discusses the operation of the ATLAS trigger system during the nominal proton-proton data collection in Run 2 with examples of special data-taking runs. Aspects of software validation, evolution of the trigger selection algorithms during Run 2, monitoring of the trigger system and data quality as well as trigger configuration are presented.
This paper describes a study of techniques for identifying Higgs bosons at high transverse momenta decaying into bottom-quark pairs,
H
→
b
b
¯
, for proton–proton collision data collected by the ...ATLAS detector at the Large Hadron Collider at a centre-of-mass energy
s
=
13
TeV
. These decays are reconstructed from calorimeter jets found with the anti-
k
t
R
=
1.0
jet algorithm. To tag Higgs bosons, a combination of requirements is used:
b
-tagging of
R
=
0.2
track-jets matched to the large-
R
calorimeter jet, and requirements on the jet mass and other jet substructure variables. The Higgs boson tagging efficiency and corresponding multijet and hadronic top-quark background rejections are evaluated using Monte Carlo simulation. Several benchmark tagging selections are defined for different signal efficiency targets. The modelling of the relevant input distributions used to tag Higgs bosons is studied in 36 fb
-
1
of data collected in 2015 and 2016 using
g
→
b
b
¯
and
Z
(
→
b
b
¯
)
γ
event selections in data. Both processes are found to be well modelled within the statistical and systematic uncertainties.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
OBJECTIVE
To assess the involvement of the multidrug resistance‐associated protein 1 (MRP1) and the glutathione pathway in the multidrug resistant (MDR) phenotype of prostate cancer in vitro.
...MATERIALS AND METHODS
Chemoselection of human prostate cancer cell lines PC3 and DU145 with etoposide resulted in the resistant cell lines PC3‐R and DU‐R. Resistance against etoposide, doxorubicin and vincristine, and its reversal with leukotriene D4 antagonists MK‐571 and zafirlukast, and buthionine sulfoximine (BSO), was assessed using tetrazolium‐dye viability assays. Western blot analysis of MRP1 expression and glutathione content were measured, and MRP1 function assessed in fluorescence assays.
RESULTS
MRP1 was increased in the MDR models; the glutathione content was significantly higher in PC3‐R but there was no increase in glutathione in DU‐R. Adding non‐toxic doses of MK‐571, zafirlukast or BSO significantly increased the sensitivity of the MDR models to cytotoxic drugs. MRP1 function was inhibited with MK‐571 in the MDR models.
CONCLUSION
MRP1 and glutathione mediate MDR in newly developed prostate cancer models.
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The momentum measurement capability of the ATLAS muon spectrometer relies fundamentally on the intrinsic single-hit spatial resolution of the monitored drift tube precision tracking chambers. Optimal ...resolution is achieved with a dedicated calibration program that addresses the specific operating conditions of the 354 000 high-pressure drift tubes in the spectrometer. The calibrations consist of a set of timing offsets and drift time to drift distance transfer relations, and result in chamber resolution functions. This paper describes novel algorithms to obtain precision calibrations from data collected by ATLAS in LHC Run 2 and from a gas monitoring chamber, deployed in a dedicated gas facility. The algorithm output consists of a pair of correction constants per chamber which are applied to baseline calibrations, and determined to be valid for the entire ATLAS Run 2. The final single-hit spatial resolution, averaged over 1172 monitored drift tube chambers, is 81.7±2.2μm.
Technical design of the phase I Mu3e experiment Arndt, K.; Augustin, H.; Baesso, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2021, Letnik:
1014
Journal Article
Recenzirano
Odprti dostop
The Mu3e experiment aims to find or exclude the lepton flavour violating decay μ→eee at branching fractions above 10−16. A first phase of the experiment using an existing beamline at the Paul ...Scherrer Institute (PSI) is designed to reach a single event sensitivity of 2⋅10−15. We present an overview of all aspects of the technical design and expected performance of the phase I Mu3e detector. The high rate of up to 108 muon decays per second and the low momenta of the decay electrons and positrons pose a unique set of challenges, which we tackle using an ultra thin tracking detector based on high-voltage monolithic active pixel sensors combined with scintillating fibres and tiles for precise timing measurements.
The Compact Linear Collider (CLIC) is an option for a future
e
+
e
-
collider operating at centre-of-mass energies up to
3
TeV
, providing sensitivity to a wide range of new physics phenomena and ...precision physics measurements at the energy frontier. This paper is the first comprehensive presentation of the Higgs physics reach of CLIC operating at three energy stages:
s
=
350
GeV
, 1.4 and
3
TeV
. The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung (
e
+
e
-
→
Z
H
) and
W
W
-fusion (
e
+
e
-
→
H
ν
e
ν
¯
e
), resulting in precise measurements of the production cross sections, the Higgs total decay width
Γ
H
, and model-independent determinations of the Higgs couplings. Operation at
s
>
1
TeV
provides high-statistics samples of Higgs bosons produced through
W
W
-fusion, enabling tight constraints on the Higgs boson couplings. Studies of the rarer processes
e
+
e
-
→
t
t
¯
H
and
e
+
e
-
→
H
H
ν
e
ν
¯
e
allow measurements of the top Yukawa coupling and the Higgs boson self-coupling. This paper presents detailed studies of the precision achievable with Higgs measurements at CLIC and describes the interpretation of these measurements in a global fit.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
The Compact Linear Collider (CLIC) is a proposed future high-luminosity linear electron-positron collider operating at three energy stages, with nominal centre-of-mass energies
s
= 380 GeV, ...1
.
5 TeV, and 3 TeV. Its aim is to explore the energy frontier, providing sensitivity to physics beyond the Standard Model (BSM) and precision measurements of Standard Model processes with an emphasis on Higgs boson and top-quark physics. The opportunities for top-quark physics at CLIC are discussed in this paper. The initial stage of operation focuses on top-quark pair production measurements, as well as the search for rare flavour-changing neutral current (FCNC) top-quark decays. It also includes a top-quark pair production threshold scan around 350 GeV which provides a precise measurement of the top-quark mass in a well-defined theoretical framework. At the higher-energy stages, studies are made of top-quark pairs produced in association with other particles. A study of t
̄
tH production including the extraction of the top Yukawa coupling is presented as well as a study of vector boson fusion (VBF) production, which gives direct access to high-energy electroweak interactions. Operation above 1 TeV leads to more highly collimated jet environments where dedicated methods are used to analyse the jet constituents. These techniques enable studies of the top-quark pair production, and hence the sensitivity to BSM physics, to be extended to higher energies. This paper also includes phenomenological interpretations that may be performed using the results from the extensive top-quark physics programme at CLIC.
Optical links are used for the readout of the 4088 silicon microstrip modules that make up the SemiConductor Tracker of the ATLAS experiment at the CERN Large Hadron Collider (LHC). The optical link ...requirements are reviewed, with particular emphasis on the very demanding environment at the LHC. The on-detector components have to operate in high radiation levels for 10 years, with no maintenance, and there are very strict requirements on power consumption, material and space. A novel concept for the packaging of the on-detector optoelectronics has been developed to meet these requirements. The system architecture, including its redundancy features, is explained and the critical on-detector components are described. The results of the extensive Quality Assurance performed during all steps of the assembly are discussed.
Objectives
The classical multidrug resistance (MDR) gene MDR1 (ABCB1) encodes for the drug efflux pump P‐glycoprotein (P‐gp). P‐gp expression is an adverse prognostic factor for treatment outcome in ...acute myeloid leukemia (AML) and is more frequently observed in older patients. Single‐nucleotide polymorphisms of the ABCB1 gene, C1236T, G2677T, and C3435T, have been associated with altered drug metabolism and treatment outcome. We prospectively determined these single‐nucleotide polymorphisms in AML blasts in a cohort of patients aged 60 years or older with AML and evaluated their relevance with regard to P‐gp function and expression, ABCB1 messenger ribonucleic acid (mRNA) expression, and clinical outcome.
Methods
We have analyzed purified bone marrow‐derived leukemic blasts, obtained at diagnosis, in 150 patients who were treated within a multicenter, randomized, phase 3 trial of elderly patients with AML. The significance of the allelic ABCB1 variants of C1236T, G2677T, and C3435T was evaluated with respect to P‐gp expression and function in leukemic blasts and ABCB1 mRNA expression levels, and these values were correlated with treatment outcome.
Results
P‐gp function and expression in leukemic blasts and ABCB1 mRNA levels in patients with AML did not vary significantly among any of the allelic variants of ABCB1. None of these allelic variations predicted a difference in complete response rate and survival endpoints.
Conclusions
In AML patients aged 60 years or older, allelic ABCB1 variations of C1236T, G2677T, or C3435T are not associated with altered P‐gp function or with MDR1 expression at the transcriptional or translational level in leukemic blasts, and they do not significantly affect clinical prognosis.
Clinical Pharmacology & Therapeutics (2006) 80, 427–439; doi: 10.1016/j.clpt.2006.07.005
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