Probing New Physics using top quark polarization in the e+e- -> t \bar{t} process at future Linear Colliders

We investigate the sensitivity to new physics of the process e+e- -> t bar{t} when the top polarization is analyzed using leptonic final states e+e- -> t \bar{t} -> l+l- b \bar{b} nu_l \bar{nu}_l. We first show that the kinematical reconstruction of the complete kinematics is experimentally tractable for this process. Then we apply the matrix element method to study the sensitivity to the Vt\bar{t} coupling (V being a vector gauge boson), at the tree level and in the narrow width approximation. Assuming the ILC baseline configuration, sqrt{S}=500 GeV, and a luminosity of 500 fb^{-1}, we conclude that this optimal analysis allows to determine simultaneously the ten form factors that parameterize the Vt\bar{t} coupling, below the percent level. We also discuss the effects of the next leading order (NLO) electroweak corrections using the GRACE program with polarized beams. It is found that the NLO corrections to different beam polarization lead to significantly different patterns of contributions.Comment: 14 pages, 4 figures, Proceedings for the TYL-FJPPL workshops on "Top Physics at ILC

Quasi-optical Measurement for Low Loss Material Characterization in Submillimeter Wave Range

An accurate knowledge of dielectric constant of materials is required in many sub-millimeter wave applications. Free-space measurement of materials has always been one of the first choices due to their non-destructive nature and relatively simple sample preparation. However, free-space measurement systems at sub-millimeter frequency range suffer from two main problems: high loss because of divergent beam pattern and diffraction when the beam waist of the radiated beam is relatively large compared to the size of the sample under tests. In order to mitigate these issues, we set up a quasi-optical system using off-axis parabolic mirrors, which enhance the dynamic range and accuracy of the system. Mirrors are preferred over lenses because of their very low absorption loss. Signals from 75 GHz to 750 GHz are generated by using a vector network analyzer and a frequency extender system in six bands. Our setup consists of a pair of horn antennas operates as feed for two off-axis parabolic mirrors. Once a collimated beam is generated, we measure its characteristics using Gaussian beam mode analysis. The sample under test is then inserted midway between the two mirrors where the beam is collimated. We have measured electric permittivity of material like high-density polyethylene and polypropylene and our results highly agree with already published papers. In the future, we would like to measure some less well-known materials to see if they are suitable for sub-millimeter electronics applications

Parameter Assessment of Beam Transport Line for Nuclear Physics Research

The IBA CP30 cyclotron was installed at the 108 Central Hospital in Hanoi, Vietnam. A proton beam with energy range from 15 to 30 MeV can be delivered by this facility. Currently, facility is mainly used for medical radioactive isotope production. There is an idea to use this accelerator for scientific research as well. For this purpose, a new beam line should be designed. A high energy resolution with minimum momentum spread is a key point for designing. A preliminary design of the beam line using matrix codes, modeling 3D optical elements, magnetic field calculations, and beam dynamics analysis is presented in this paper

Replay detection and multi-stream synchronization in CS:GO game streams using content-based Image retrieval and Image signature matching

In GameStory: The 2019 Video Game Analytics Challenge, two main tasks are nominated to solve in the challenge, which are replay detection - multi-stream synchronization, and game story summarization. In this paper, we propose a data-driven based approach to solve the first task: replay detection - multi-stream synchronization. Our solution aims to determine the replays which lie between two logo-transitional endpoints and synchronize them with their sources by extracting frames from videos, then applying image processing and retrieval remedies. In detail, we use the Bag of Visual Words approach to detect the logo-transitional endpoints, which contains multiple replays in between, then employ an Image Signature Matching algorithm for multi-stream synchronization and replay boundaries refinement. The best configuration of our proposed solution manages to achieve the second-highest scores in all evaluation metrics of the challenge

Investigation of GAS Gain of GEM-Foil Used in Low Energy Radioactive Beam Experiments

Study of nuclear reactions using radioactive beams at low energy plays an important role in nuclear astrophysics and nuclear structure. The trajectory of particle beams can be obtained by using an active gas target, multiple-sampling and tracking proportional chamber (MSTPC). Because of low intensity of radioactive beam when studying the stellar nuclear reactions such as (α, p), (p, α),… it is necessary to increase the gain of the tracking counter system. A Gas Electron Multiplier (GEM) foil and the proportional counter called as GEM-MSTPC have been used for this purpose. In this study, the dependence of the effective gas gain of GEM foils on the foil thickness and on the operating pressure was investigated. Two types of GEM foil with the thickness of 400 μm and 200 μm in Argon (70%) – Carbon dioxide (30%) mixture have been used. This investigation is important for our direct measurement of 22Mg(α, p) reaction, which is planed to perform in 2012 at RIKEN

Radiation Dose Estimation of Cement Samples Used in Lao PDR

The natural radioactivity due to presence of 226Ra, 232Th and 40K radionuclides in Lao PDR cements was measured for first time using a gamma-spectrometry with HPGe detector. Two different types of cement produced by 4 local cement companies in Lao PDR have been investigated.  The specific radioactivity of 226Ra, 232Th and 40K in the investigated samples ranged from 24.83 ± 1.18  to 54.39 ± 5.90  Bq kg-1 with a mean of 37.76 ± 10.71 Bq kg-1, 6.63 ± 1.59 to 21.17 ± 0.48 Bq kg-1 with a mean of 13.77 ± 5.85 Bq kg-1 and 43.28 ± 7.68 to 168.70 ± 3.34 Bq kg-1 with a mean of 116.07 ± 47.50 Bq kg-1, respectively. The radium equivalent activity (Raeq), the gamma-index, the external and internal hazard indices, Absorb Dose Rate in Air (D) and Annual Effective Dose Equivalent (AEDE) were estimated for the radiation hazard of the natural radioactivity in all cement samples. The obtained results were compared with the corresponding values for cement of different countries. The calculated Raeq values of Lao PDR samples are lower than the limit of 370 Bq kg-1 set fo building materials. The mean indoor absorbed dose rate is slightly lower than the population-weighted average of 84 nGy h-1 while the corresponding effective dose was 79% less than the dose ft of 1 mSv y-1. The results obtained in this study show no significant radiological hazards arising from using Lao PDR cement for construction of houses

Feasibility Study of Direct Measurement of Stellar Reaction 22Mg(α,p)25Al

The stellar reaction 22Mg(α,p)25Al plays an important role for understanding the nucleosynthesis of stars. It has never investigated yet. We are planning to study this reaction in environment of X-rays burst with temperature T9 = 1÷3 GK using invert kinematics and thick target method. This paper shows a design for direct investigation of this reaction by simulation method. This design is necessary for experimental setup and for confirmation of the feasibility of the experiment

Improving Object Detection in Medical Image Analysis through Multiple Expert Annotators: An Empirical Investigation

The work discusses the use of machine learning algorithms for anomaly detection in medical image analysis and how the performance of these algorithms depends on the number of annotators and the quality of labels. To address the issue of subjectivity in labeling with a single annotator, we introduce a simple and effective approach that aggregates annotations from multiple annotators with varying levels of expertise. We then aim to improve the efficiency of predictive models in abnormal detection tasks by estimating hidden labels from multiple annotations and using a re-weighted loss function to improve detection performance. Our method is evaluated on a real-world medical imaging dataset and outperforms relevant baselines that do not consider disagreements among annotators.Comment: This is a short version submitted to the Midwest Machine Learning Symposium (MMLS 2023), Chicago, IL, US