The CMS Phase-1 pixel detector upgrade Lowette, S.; Moortgat, S.; Deng, W. ...
Journal of instrumentation,
02/2021, Letnik:
16, Številka:
2
Journal Article
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The CMS detector at the CERN LHC features a silicon pixel detector as its innermost subdetector. The original CMS pixel detector has been replaced with an upgraded pixel system (CMS Phase-1 pixel ...detector) in the extended year-end technical stop of the LHC in 2016/2017. The upgraded CMS pixel detector is designed to cope with the higher instantaneous luminosities that have been achieved by the LHC after the upgrades to the accelerator during the first long shutdown in 2013–2014. Compared to the original pixel detector, the upgraded detector has a better tracking performance and lower mass with four barrel layers and three endcap disks on each side to provide hit coverage up to an absolute value of pseudorapidity of 2.5. This paper describes the design and construction of the CMS Phase-1 pixel detector as well as its performance from commissioning to early operation in collision data-taking.
Chronic granulomatous disease (CGD) is an inherited primary immunodeficiency characterized by phagocytes devoid of a functioning nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. The ...failure of CGD phagocytes to produce reactive oxygen species (ROS) results in a marked increase in the susceptibility of affected patients to life-threatening bacterial and fungal infections. This study investigated whether loading of CGD phagocytes with glucose oxidase (GO)–containing liposomes (GOLs) could restore cellular production of bactericidal ROS (eg, H2O2 and HOCl) in vitro. Results indicate that GO encapsulated in liposomes enabled NADPH oxidase-deficient phagocytes to use H2O2 for the production of highly bactericidal HOCl. The intracellular colocalization of bacteria and liposomes (or liposome-derived ferritin) was demonstrated by confocal laser microscopy and electron microscopy. After uptake of GOLs (approximately 0.2 U/mL at 1 mM total lipid concentration, size approximately 180 nm), CGD granulocytes produced HOCl levels comparable to those of normal phagocytes. Remarkably, after treatment with GOLs, CGD phagocytes killed Staphylococcus aureus as efficiently as normal granulocytes. Moreover, treated cells retained sufficient motility toward chemotactic stimuli as measured by chemotaxis assay. Side effects were evaluated by measuring the H2O2 concentrations and the production of methemoglobin in whole blood. These studies revealed that H2O2 produced by GOLs was degraded immediately by the antioxidative capacity of whole blood. Elevated methemoglobin levels were observed only after application of extremely high amounts of GOLs (2 U/mL). In summary, the application of negatively charged GOLs might provide a novel effective approach in the treatment of patients with CGD at high risk for life-threatening infections.
Muon Collider Forum report Black, K.M.; Li, D.; Stratakis, D. ...
Journal of instrumentation,
02/2024, Letnik:
19, Številka:
2
Journal Article
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Abstract A multi-TeV muon collider offers a spectacular opportunity in the direct exploration of the energy frontier. Offering a combination of unprecedented energy collisions in a comparatively ...clean leptonic environment, a high energy muon collider has the unique potential to provide both precision measurements and the highest energy reach in one machine that cannot be paralleled by any currently available technology. The topic generated a lot of excitement in Snowmass meetings and continues to attract a large number of supporters, including many from the early career community. In light of this very strong interest within the US particle physics community, Snowmass Energy, Theory and Accelerator Frontiers created a cross-frontier Muon Collider Forum in November of 2020. The Forum has been meeting on a monthly basis and organized several topical workshops dedicated to physics, accelerator technology, and detector R&D. Findings of the Forum are summarized in this report.
We report the observation of the X(3872) in the J/psipi(+)pi(-) channel, with J/psi decaying to mu(+)mu(-), in p (p) over bar collisions at roots=1.96 TeV. Using approximately 230 pb(-1) of data ...collected with the Run II D0 detector, we observe 522+/-100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9+/-3.1(stat)+/-3.0(syst) MeV/c(2). We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the psi(2S) state.
We present a search for flavor changing neutral currents in decays of top quarks. The analysis is based on a search for tt¯→ℓ′νℓℓ¯+jets (ℓ,ℓ′=e,μ) final states using 4.1 fb−1 of integrated luminosity ...of pp¯ collisions at s=1.96 TeV. We extract limits on the branching ratio B(t→Zq) (q=u,c quarks), assuming anomalous tuZ or tcZ couplings. We do not observe any sign of such anomalous coupling and set a limit of B<3.2% at 95% C.L.
Abstract
The Large Hadron Collider at CERN will undergo an upgrade in
order to increase its luminosity to
7.5 × 10
34
cm
-2
s
-1
. The increased luminosity
during this High-Luminosity running phase, ...starting around 2029,
means a higher rate of proton-proton interactions, hence a larger
ionizing dose and particle fluence for the detectors. The current
tracking system of the CMS experiment will be fully replaced in
order to cope with the new operating conditions. Prototype planar
pixel sensors for the CMS Inner Tracker with square
50 μm × 50 μm and rectangular
100 μm × 25 μm pixels read out by the
RD53A chip were characterized in the lab and at the DESY-II testbeam
facility in order to identify designs that meet the requirements of
CMS during the High-Luminosity running phase. A spatial resolution
of approximately 3.4 μm (2 μm) is obtained using the
modules with 50 μm × 50 μm
(100 μm × 25 μm) pixels at the optimal
angle of incidence before irradiation. After irradiation to a 1 MeV
neutron equivalent fluence of
Φ
eq
= 5.3 × 10
15
cm
-2
, a resolution of
9.4 μm is achieved at a bias voltage of 800 V using a module
with 50 μm × 50 μm pixel size. All modules
retain a hit efficiency in excess of 99% after irradiation to
fluences up to 2.1 × 10
16
cm
-2
. Further studies of
the electrical properties of the modules, especially crosstalk, are
also presented in this paper.
Abstract
The Large Hadron Collider (LHC) at CERN will undergo major
upgrades to increase the instantaneous luminosity up to
5–7.5×10
34
cm
-2
s
-1
. This High Luminosity
upgrade of the LHC (HL-LHC) ...will deliver a total of
3000–4000 fb
-1
of proton-proton collisions at a
center-of-mass energy of 13–14 TeV. To cope with these
challenging environmental conditions, the strip tracker of the CMS
experiment will be upgraded using modules with two closely-spaced
silicon sensors to provide information to include tracking in the
Level-1 trigger selection. This paper describes the performance, in
a test beam experiment, of the first prototype module based on the
final version of the CMS Binary Chip front-end ASIC before and after
the module was irradiated with neutrons. Results demonstrate that
the prototype module satisfies the requirements, providing efficient
tracking information, after being irradiated with a total fluence
comparable to the one expected through the lifetime of the
experiment.
b-Jet identification in the D0 experiment Adams, M.; Alton, A.; Askew, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2010, Letnik:
620, Številka:
2
Journal Article
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Algorithms distinguishing jets originating from b quarks from other jet flavors are important tools in the physics program of the D0 experiment at the Fermilab Tevatron
p
p
¯
collider. This article ...describes the methods that have been used to identify b-quark jets, exploiting in particular the long lifetimes of b-flavored hadrons, and the calibration of the performance of these algorithms based on collider data.
Abstract
The CMS Inner Tracker, made of silicon pixel modules, will
be entirely replaced prior to the start of the High Luminosity LHC
period. One of the crucial components of the new Inner Tracker
...system is the readout chip, being developed by the RD53
Collaboration, and in particular its analogue front-end, which
receives the signal from the sensor and digitizes it. Three
different analogue front-ends (Synchronous, Linear, and
Differential) were designed and implemented in the RD53A
demonstrator chip. A dedicated evaluation program was carried out to
select the most suitable design to build a radiation tolerant pixel
detector able to sustain high particle rates with high efficiency
and a small fraction of spurious pixel hits. The test results showed
that all three analogue front-ends presented strong points, but also
limitations. The Differential front-end demonstrated very low noise,
but the threshold tuning became problematic after
irradiation. Moreover, a saturation in the preamplifier feedback
loop affected the return of the signal to baseline and thus
increased the dead time. The Synchronous front-end showed very good
timing performance, but also higher noise. For the Linear front-end
all of the parameters were within specification, although this
design had the largest time walk. This limitation was addressed and
mitigated in an improved design. The analysis of the advantages and
disadvantages of the three front-ends in the context of the CMS
Inner Tracker operation requirements led to the selection of the
improved design Linear front-end for integration in the final CMS
readout chip.
The standard model of particle physics contains parameters-such as particle masses-whose origins are still unknown and which cannot be predicted, but whose values are constrained through their ...interactions. In particular, the masses of the top quark (Mt) and W boson (MW) constrain the mass of the long-hypothesized, but thus far not observed, Higgs boson. A precise measurement of Mt can therefore indicate where to look for the Higgs, and indeed whether the hypothesis of a standard model Higgs is consistent with experimental data. As top quarks are produced in pairs and decay in only about 10-24 s into various final states, reconstructing their masses from their decay products is very challenging. Here we report a technique that extracts more information from each top-quark event and yields a greatly improved precision (of ± 5.3 GeV/c2) when compared to previous measurements. When our new result is combined with our published measurement in a complementary decay mode and with the only other measurements available, the new world average for Mt becomes 178.0 ± 4.3 GeV/c2. As a result, the most likely Higgs mass increases from the experimentally excluded value of 96 to 117 GeV/c2, which is beyond current experimental sensitivity. The upper limit on the Higgs mass at the 95% confidence level is raised from 219 to 251 GeV/c2.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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