3,403 research outputs found
Cerium (IV) Oxide Reinforced Lithium-Borotellurite Glasses: A Characterization Study Through Physical, Optical, Structural and Radiation Shielding Properties
The purpose of this study was to characterize the structural, optical, and physical properties of various kinds of glasses based on the 50TeO2–30B2O3-(20-x)Li2O-xCeO2 system (x = 0, 0.5, 1, 2, 3, 4, 5, 10, 15, 20). Consequently, ten glass samples were produced by melting-annealing. Calculations of the densities of the synthesized glasses were performed using the Archimedes technique. The sample's structural, optical, physical, and radiation interaction properties were determined using XRD analysis, Raman spectroscopy, and advanced modelling techniques with FLUKA code, yielding optical band gap, refractive index, and Urbach energy values. By increasing the CeO2 reinforcement from 0 to 20 mol %, the glass densities rose from 4.0614 to 4.7519 g cm−3. The transmittance spectra of TBLC glasses were found in the range of 200–1100 nm. Our findings showed that the lowest Urbach energy belonged to the TBLC1 sample, and the highest Urbach energy belonged to the TBLC20 sample. When the CeO2 ratio was raised, the optical transmittance and absorption characteristics changed nearly monotonically, suggesting that these qualities may be calculated and controlled using the CeO2 additive, as shown in this experiment. By substituting CeO2 for Li2O inside the structure, it was possible to substantially enhance the optical band gap. Additionally, at simulated energies greater than 0.02 MeV, the gamma-ray linear attenuation coefficient rises monotonically with CeO2 reinforcement. Consequently, linear attenuation coefficients were reported as 125.843 cm−1, 127.601 cm−1, 129.211 cm−1, 132.312 cm−1, 135.166 cm−1, 138.705 cm−1, 141.288 cm−1, 156.690 cm−1, 172.393 cm−1, 186.811 cm−1 for TBLC0, TBLC0.5, TBLC1, TBLC2, TBLC3, TBLC4, TBLC5, TBL10, TBLC15 and TBLC20 at 0.015 MeV, respectively. It can be concluded that combination of high-concentration CeO2 and TeO2–B2O3 glass is an excellent synergetic tool for combining structural, optical, and radiation properties when combined with other materials. © 2021 Elsevier Ltd and Techna Group S.r.l.The research activity is supported by Eskisehir Osmangazi University, Scientific Research Council with grant number 202019D20
Operational experience, improvements, and performance of the CDF Run II silicon vertex detector
The Collider Detector at Fermilab (CDF) pursues a broad physics program at
Fermilab's Tevatron collider. Between Run II commissioning in early 2001 and
the end of operations in September 2011, the Tevatron delivered 12 fb-1 of
integrated luminosity of p-pbar collisions at sqrt(s)=1.96 TeV. Many physics
analyses undertaken by CDF require heavy flavor tagging with large charged
particle tracking acceptance. To realize these goals, in 2001 CDF installed
eight layers of silicon microstrip detectors around its interaction region.
These detectors were designed for 2--5 years of operation, radiation doses up
to 2 Mrad (0.02 Gy), and were expected to be replaced in 2004. The sensors were
not replaced, and the Tevatron run was extended for several years beyond its
design, exposing the sensors and electronics to much higher radiation doses
than anticipated. In this paper we describe the operational challenges
encountered over the past 10 years of running the CDF silicon detectors, the
preventive measures undertaken, and the improvements made along the way to
ensure their optimal performance for collecting high quality physics data. In
addition, we describe the quantities and methods used to monitor radiation
damage in the sensors for optimal performance and summarize the detector
performance quantities important to CDF's physics program, including vertex
resolution, heavy flavor tagging, and silicon vertex trigger performance.Comment: Preprint accepted for publication in Nuclear Instruments and Methods
A (07/31/2013
Percutaneous Coronary Interventions Using a Ridaforolimus-Eluting Stent in Patients at High Bleeding Risk.
BACKGROUND: Patients treated with percutaneous coronary intervention are often considered to be at a high bleeding risk (HBR). Drug-eluting stents have been shown to be superior to bare-metal stents in patients with HBR, even when patients were given abbreviated periods of dual antiplatelet therapy (DAPT). Short DAPT has not been evaluated with the EluNIR ridaforolimus-eluting stent. The aim of this study was to evaluate the safety and efficacy of a shortened period of DAPT following implantation of the ridaforolimus-eluting stent in patients with HBR. METHODS AND RESULTS: This was a prospective, multicenter, binational, single-arm, open-label trial. Patients were defined as HBR according to the LEADERS-FREE (Prospective Randomized Comparison of the BioFreedom Biolimus A9 Drug-Coated Stent versus the Gazelle Bare-Metal Stent in Patients at High Bleeding Risk) trial criteria. After percutaneous coronary intervention, DAPT was given for 1 month to patients presenting with stable angina. In patients presenting with an acute coronary syndrome, DAPT was given for 1 to 3 months, at the investigator's discretion. The primary end point was a composite of cardiac death, myocardial infarction, or stent thrombosis up to 1 year (Academic Research Consortium definite and probable). Three hundred fifteen patients undergoing percutaneous coronary intervention were enrolled, and 56.4% presented with acute coronary syndrome; 33.7% were receiving oral anticoagulation. At 1 year, the primary end point occurred in 15 patients (4.9%), meeting the prespecified performance goal of 14.1% (P<0.0001). Stent thrombosis (Academic Research Consortium definite and probable) occurred in 2 patients (0.6%). Bleeding Academic Research Consortium type 3 and 5 bleeding occurred in 6 patients (1.9%). CONCLUSIONS: We observed favorable results in patients with HBR who underwent percutaneous coronary intervention with a ridaforolimus-eluting stent and received shortened DAPT, including a low rate of ischemic events and low rate of stent thrombosis. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03877848
Structural Characterization and Gamma-Ray Attenuation Properties of Rice-Like α-TeO2 Crystalline Microstructures (CMS) Grown Rapidly on Free Surface of Tellurite-Based Glasses
In this study, we extensively analyzed the structural, physical and gamma-ray attenuation properties of α-TeO2 CMS, which has unexpectedly been observed as a part of Sm2O3 doped TeO2–B2O3–V2O5 glasses synthesis process. The shape of α-TeO2 CMS was obtained from SEM analyses. Moreover, EDX, XRD and Raman examinations were utilized for systematic characterization of α-TeO2 CMS. In addition to experimental physical and structural studies on α-TeO2 CMSs, gamma-ray attenuation properties were also determined and compared with Quartz and some novel glasses such as PNCKM5, C25, SCNZ7 along with some commercial glasses such as RS253, RS253G18, RS323G19, RS360, RS520 using FLUKA general-purpose Monte Carlo code. EDX results indicated that only Te and O elements were available in the α-TeO2 CMS. The finding showed that gamma-ray attenuation competencies of α-TeO2 CMS is higher than many novel and commercial glasses in addition to traditional concrete shields. It can be concluded that further comparison studies can be done between normal glass structure and α-TeO2 CMS (or similar) occurred glass structures in terms of better understanding the total gamma-ray attenuation and the effect of α-TeO2 CMS. © 2021 The Author(s).The authors thank Taif University Researchers Supporting Project number (TURSP-2020/12), Taif University, Taif, Saudi Arabia. The APC was covered by "Dunarea de Jos" University of Galati, Romania
Multi-Jet Event Rates in Deep Inelastic Scattering and Determination of the Strong Coupling Constant
Jet event rates in deep inelastic ep scattering at HERA are investigated
applying the modified JADE jet algorithm. The analysis uses data taken with the
H1 detector in 1994 and 1995. The data are corrected for detector and
hadronization effects and then compared with perturbative QCD predictions using
next-to-leading order calculations. The strong coupling constant alpha_S(M_Z^2)
is determined evaluating the jet event rates. Values of alpha_S(Q^2) are
extracted in four different bins of the negative squared momentum
transfer~\qq in the range from 40 GeV2 to 4000 GeV2. A combined fit of the
renormalization group equation to these several alpha_S(Q^2) values results in
alpha_S(M_Z^2) = 0.117+-0.003(stat)+0.009-0.013(syst)+0.006(jet algorithm).Comment: 17 pages, 4 figures, 3 tables, this version to appear in Eur. Phys.
J.; it replaces first posted hep-ex/9807019 which had incorrect figure 4
Differential (2+1) Jet Event Rates and Determination of alpha_s in Deep Inelastic Scattering at HERA
Events with a (2+1) jet topology in deep-inelastic scattering at HERA are
studied in the kinematic range 200 < Q^2< 10,000 GeV^2. The rate of (2+1) jet
events has been determined with the modified JADE jet algorithm as a function
of the jet resolution parameter and is compared with the predictions of Monte
Carlo models. In addition, the event rate is corrected for both hadronization
and detector effects and is compared with next-to-leading order QCD
calculations. A value of the strong coupling constant of alpha_s(M_Z^2)=
0.118+- 0.002 (stat.)^(+0.007)_(-0.008) (syst.)^(+0.007)_(-0.006) (theory) is
extracted. The systematic error includes uncertainties in the calorimeter
energy calibration, in the description of the data by current Monte Carlo
models, and in the knowledge of the parton densities. The theoretical error is
dominated by the renormalization scale ambiguity.Comment: 25 pages, 6 figures, 3 tables, submitted to Eur. Phys.
Measurements of Transverse Energy Flow in Deep-Inelastic Scattering at HERA
Measurements of transverse energy flow are presented for neutral current
deep-inelastic scattering events produced in positron-proton collisions at
HERA. The kinematic range covers squared momentum transfers Q^2 from 3.2 to
2,200 GeV^2, the Bjorken scaling variable x from 8.10^{-5} to 0.11 and the
hadronic mass W from 66 to 233 GeV. The transverse energy flow is measured in
the hadronic centre of mass frame and is studied as a function of Q^2, x, W and
pseudorapidity. A comparison is made with QCD based models. The behaviour of
the mean transverse energy in the central pseudorapidity region and an interval
corresponding to the photon fragmentation region are analysed as a function of
Q^2 and W.Comment: 26 pages, 8 figures, submitted to Eur. Phys.
Inclusive Production Cross Sections from 920 GeV Fixed Target Proton-Nucleus Collisions
Inclusive differential cross sections and
for the production of \kzeros, \lambdazero, and
\antilambda particles are measured at HERA in proton-induced reactions on C,
Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to
GeV in the proton-nucleon system. The ratios of differential
cross sections \rklpa and \rllpa are measured to be and , respectively, for \xf . No significant dependence upon the
target material is observed. Within errors, the slopes of the transverse
momentum distributions also show no significant
dependence upon the target material. The dependence of the extrapolated total
cross sections on the atomic mass of the target material is
discussed, and the deduced cross sections per nucleon are
compared with results obtained at other energies.Comment: 17 pages, 7 figures, 5 table
Searches at HERA for Squarks in R-Parity Violating Supersymmetry
A search for squarks in R-parity violating supersymmetry is performed in e^+p
collisions at HERA at a centre of mass energy of 300 GeV, using H1 data
corresponding to an integrated luminosity of 37 pb^(-1). The direct production
of single squarks of any generation in positron-quark fusion via a Yukawa
coupling lambda' is considered, taking into account R-parity violating and
conserving decays of the squarks. No significant deviation from the Standard
Model expectation is found. The results are interpreted in terms of constraints
within the Minimal Supersymmetric Standard Model (MSSM), the constrained MSSM
and the minimal Supergravity model, and their sensitivity to the model
parameters is studied in detail. For a Yukawa coupling of electromagnetic
strength, squark masses below 260 GeV are excluded at 95% confidence level in a
large part of the parameter space. For a 100 times smaller coupling strength
masses up to 182 GeV are excluded.Comment: 32 pages, 14 figures, 3 table
Multiplicity Structure of the Hadronic Final State in Diffractive Deep-Inelastic Scattering at HERA
The multiplicity structure of the hadronic system X produced in
deep-inelastic processes at HERA of the type ep -> eXY, where Y is a hadronic
system with mass M_Y< 1.6 GeV and where the squared momentum transfer at the pY
vertex, t, is limited to |t|<1 GeV^2, is studied as a function of the invariant
mass M_X of the system X. Results are presented on multiplicity distributions
and multiplicity moments, rapidity spectra and forward-backward correlations in
the centre-of-mass system of X. The data are compared to results in e+e-
annihilation, fixed-target lepton-nucleon collisions, hadro-produced
diffractive final states and to non-diffractive hadron-hadron collisions. The
comparison suggests a production mechanism of virtual photon dissociation which
involves a mixture of partonic states and a significant gluon content. The data
are well described by a model, based on a QCD-Regge analysis of the diffractive
structure function, which assumes a large hard gluonic component of the
colourless exchange at low Q^2. A model with soft colour interactions is also
successful.Comment: 22 pages, 4 figures, submitted to Eur. Phys. J., error in first
submission - omitted bibliograph
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