Strangeness production in two-particle azimuthal correlations on the near and away side measured with ALICE in pp collisions at 7 TeV

Two-particle azimuthal correlations allow one to study high-$p_{\rm T}$ parton fragmentation without full jet reconstruction. Enhancements of the azimuthal correlations are seen at $\Delta \varphi \approx 0$ and $\Delta \varphi \approx \pi$, resulting from back-to-back jet fragmentation in the parton center-of-mass system. We present the current status of the study of correlations between charged trigger particles and associated strange baryons ($\Lambda$) and mesons (K$_{S}^{0}$) in pp collisions at $\sqrt{s}$ = 7 TeV. A data-driven feeddown correction for $\Lambda$ is also presented, which could allow a more accurate calculation of the primary $\Lambda/$K$_{S}^{0}$ ratio in jets and the underlying event.Comment: 5 pages, 4 figures, Proceedings of the Second Annual Conference on Large Hadron Collider Physics (LHCP 2014), June 2-7, 2014, New Yor

Sensitivity Enhancement of an Experimental Benchtop X-Ray Fluorescence Imaging System by Deploying a Single Crystal Cadmium Telluride Detector System Optimized for High Flux X-Ray Operations

In this work, an energy-resolving thermoelectrically cooled single crystal cadmium telluride (CdTe) detector system upgraded with the latest firmware was optimized for high x-ray flux operations using high bias voltage and fast peaking time. This detector system was deployed into an experimental benchtop x-ray fluorescence (XRF) imaging/computed tomography (XFCT) system developed for quantitative imaging of metal nanoprobes such as gold nanoparticles (GNPs). Using the firmware-upgraded and existing/old CdTe detector systems, the Compton/XRF spectra from small (8 mm diameter) GNP-containing phantoms were acquired. The phantoms were irradiated with 1.8 mm Sn-filtered 125 kVp cone beam x-rays at 24 mA. The firmware-upgraded detector system produced relatively lower dead time under high x-ray flux, compared with the old detector system, and performed well with the spectral resolution of ~0.7 keV (in full width at half maximum) at 69 keV photon energy. Given the same 2 mm aperture detector collimator and irradiation time of 10 s, this detector system managed to score nearly 50% more gold XRF signals than the existing one at all GNP concentrations tested. This improvement resulted in the GNP detection limit of 0.02 wt. % which was lower than that (0.03 wt. %) achievable with the existing detector system. When combined with the detector collimator containing a larger (3 mm) aperture, the firmware-upgraded detector system produced drastically more gold XRF signal at a given GNP concentration (e.g., 9 times more for 1 wt. % GNP solution and irradiation time of 10 s), leading to further reduction in the GNP detection limit (i.e., 0.01 wt. %). The present investigation showed that the firmware upgraded CdTe detector system optimized for high x-ray flux operations allowed for better photon counting efficiency, thus leading to sensitivity enhancement of an experimental benchtop XRF/XFCT imaging system

Use of the Fully Spectroscopic Pixelated Cadmium Telluride Detector for Benchtop X-Ray Fluorescence Computed Tomography

In this work, we integrated a commercially-available fully-spectroscopic pixelated cadmium telluride (CdTe) detector system as a two-dimensional (2D) array detector into our existing benchtop cone-beam x-ray fluorescence computed tomography (XFCT) system. After integrating this detector, known as High-Energy X-ray Imaging Technology (HEXITEC), we performed quantitative imaging of gold nanoparticle (GNP) distribution in a small animal-sized phantom using our benchtop XFCT system. Owing to the upgraded detector component within our benchtop XFCT system, we were able to conduct this phantom imaging in an unprecedented manner by volumetric XFCT scans followed by XFCT image reconstruction in 3D. The current results showed that adoption of HEXITEC, in conjunction with a custom-made parallel-hole collimator, drastically reduced the XFCT scan time/dose. Compared with the previous work performed with our original benchtop XFCT system adopting a single crystal CdTe detector, the currently observed reduction was up to a factor of 5, while achieving comparable GNP detection limit under similar experimental conditions. Overall, we demonstrated, for the first time to the best our knowledge, the feasibility of benchtop XFCT imaging of small animal-sized objects containing biologically relevant GNP concentrations (on the order of 0.1 mg Au/c

Deep Learning-Based TEM Image Analysis for Fully Automated Detection of Gold Nanoparticles Internalized Within Tumor Cell

Transmission electron microscopy (TEM) imaging can be used for detection/localization of gold nanoparticles (GNPs) within tumor cells. However, quantitative analysis of GNP-containing cellular TEM images typically relies on conventional/thresholding-based methods, which are manual, time-consuming, and prone to human errors. In this study, therefore, deep learning (DL)-based methods were developed for fully automated detection of GNPs from cellular TEM images. Several models of you only look once (YOLO) v5 were implemented, with a few adjustments to enhance the model\u27s performance by applying the transfer learning approach, adjusting the size of the input image, and choosing the best optimization algorithm. Seventy-eight original (12,040 augmented) TEM images of GNP-laden tumor cells were used for model implementation and validation. A maximum F1 score (harmonic mean of the precision and recall) of 0.982 was achieved by the best-trained models, while mean average precision was 0.989 and 0.843 at 0.50 and 0.50-0.95 intersection over union threshold, respectively. These results suggested the developed DL-based approach was capable of precisely estimating the number/position of internalized GNPs from cellular TEM images. A novel DL-based TEM image analysis tool from this study will benefit research/development efforts on GNP-based cancer therapeutics, for example, by enabling the modeling of GNP-laden tumor cells using nanometer-resolution TEM images

A note on comonotonicity and positivity of the control components of decoupled quadratic FBSDE

In this small note we are concerned with the solution of Forward-Backward Stochastic Differential Equations (FBSDE) with drivers that grow quadratically in the control component (quadratic growth FBSDE or qgFBSDE). The main theorem is a comparison result that allows comparing componentwise the signs of the control processes of two different qgFBSDE. As a byproduct one obtains conditions that allow establishing the positivity of the control process.Comment: accepted for publicatio

Transverse sphericity of primary charged particles in minimum bias proton–proton collisions at √s = 0.9, 2.76 and 7 TeV

Measurements of the sphericity of primary charged particles in minimum bias proton–proton collisions at s√=0.9, 2.76 and 7 TeV with the ALICE detector at the LHC are presented. The observable is measured in the plane perpendicular to the beam direction using primary charged tracks with p T>0.5 GeV/c in |η|<0.8. The mean sphericity as a function of the charged particle multiplicity at mid-rapidity (N ch) is reported for events with different p T scales (“soft” and “hard”) defined by the transverse momentum of the leading particle. In addition, the mean charged particle transverse momentum versus multiplicity is presented for the different event classes, and the sphericity distributions in bins of multiplicity are presented. The data are compared with calculations of standard Monte Carlo event generators. The transverse sphericity is found to grow with multiplicity at all collision energies, with a steeper rise at low N ch, whereas the event generators show an opposite tendency. The combined study of the sphericity and the mean p T with multiplicity indicates that most of the tested event generators produce events with higher multiplicity by generating more back-to-back jets resulting in decreased sphericity (and isotropy). The PYTHIA6 generator with tune PERUGIA-2011 exhibits a noticeable improvement in describing the data, compared to the other tested generators

Transverse Momentum Evolution of Hadron-V0 Correlations in Proton-Proton Collisions at (sNN)\sqrt(s_NN) = 7 TeV

The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, is capable of accelerating beams of protons (pp) and heavy-ions (Pb+Pb) up to nearly the speed of light, which corresponds to center of mass energies of sqrt(s_NN) = 7 TeV and sqrt(s_NN) = 2.76 TeV, respectively. The goal of the pp program is to investigate physics of and beyond the standard model, while the heavy-ion program attempts to characterize the properties of a new state of matter, called the Quark Gluon Plasma. The main aim of this dissertation is to identify particle production mechanisms in pp collisions, also as a reference for possible modifications due to the plasma formation in heavy-ion collisions. Two-particle azimuthal correlation measurements were employed, which allow the study of high-pT parton fragmentation without full jet reconstruction. We present the results of correlations between charged trigger particles and associated strange baryons (Lambda) and mesons (K0S). Enhancements of the azimuthal correlations are seen at delta-phi = 0 and delta-phi = pi, resulting from back-to-back jet fragmentation in the parton center-of-mass system. Two model fit functions were introduced to characterize the properties of the jet peaks. Hard and soft yields were separated using the ZYAM method and extracted yields were compared with pQCD inspired models and inclusive spectra. The analysis was performed in different multiplicity bins to detect possible enhancements of Lambda or K0S yields and the Lambda/K0S ratio. The latter was observed in high multiplicity Pb+Pb collisions and interpreted as a novel production mechanism in the deconfined medium produced at the LHC. A novel data-driven feed-down correction for Lambdas is also introduced, which could allow a more accurate calculation of the primary Lambda

TRANSVERSE MOMENTUM EVOLUTION OF HADRON-V0 CORRELATIONS IN PP COLLISIONS AT 7 TEV

The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, is capable of accelerating beams of protons (pp) and heavy-ions (Pb+Pb) up to nearly the speed of light, which corresponds to center of mass energies of 7 TeV and 2.76 TeV, respectively. The goal of the pp program is to investigate physics of and beyond the standard model, while the heavy-ion program attempts to characterize the properties of a new state of matter, called the Quark Gluon Plasma. The main aim of this dissertation is to identify particle production mechanisms in pp collisions, also as a reference for possible modifications due to the plasma formation in heavy-ion collisions. Two-particle azimuthal correlation measurements were employed, which allow the study of high-pT parton fragmentation without full jet reconstruction. We present the results of correlations between charged trigger particles and associated strange baryons and mesons. Enhancements of the azimuthal correlations are seen at dphi= 0 and dphi= pi, resulting from back-to-back jet fragmentation in the parton center-of-mass system. Two model fit functions were introduced to characterize the properties of the jet peaks. Hard and soft yields were seperated using the ZYAM method and extracted yields were compared with pQCD inspired models and inclusive spectra. The analysis was performed in different multiplicity bins to detect possible enhancements of baryons or meson yields and the baryon/meson ratio. The latter was observed in high multiplicity Pb+Pb collisions and interpreted as a novel production mechanism in the deconfined medium produced at the LHC. A novel data-driven feeddown correction for Lambda is also introduced, which could allow a more accurate calculation of the primary Xi.Physics, Department o