Khuram Tariq

Over 5000 photomultiplier tubes (PMTs) are being deployed for electromagnetic particle detectors (EDs) for the Large High Altitude Air Shower Observatory (LHAASO) project. The linearity of the PMT signal is optimized using a high dynamic range base. However, the PMT gain and linearity tend to change under various lighting conditions. In this paper, the variations in the gain and linearity of the XP3960 PMT are studied by changing the signal counting rate. The PMT gain increases appreciably at high counting rates due to the voltage redistribution between the dynode stages, resulting in an apparent increase in the linearity of the dynode. The details of the characteristics of PMTs at high counting rates and the corresponding simulations are described. These results show the impact of various counting rates on PMT performances can be ignored in the ED experimental conditions.

In the Large High Altitude Air Shower Observatory (LHAASO), the main physics objective of the water Cherenkov detector array (WCDA) is to survey the sky for gamma-ray sources in the energy range of 100 GeV to 30 TeV. In order to extend the dynamic range of the WCDA, a 1.5-inch photomultiplier tube (PMT) is placed aside the 8-inch PMT in each cell of the WCDA. All of these 1.5-inch PMTs (900 in total) consist of the WCDA dynamic extended system (WCDA++). These PMTs are required to maintain linearity within four orders of magnitude. The performance of the 1.5-inch PMTs with a specially designed bi-readout voltage divider is tested with a PMT test system. Accordingly, the effects of the working high voltage and signal width on the dynamic range of the PMTs are studied. The test results show that the dynamic range with a 5% non-linearity for a driven signal width of 5.5 ns is more than 200 kPEs (photoelectrons). The dark noise count rate is less than 200 Hz for a 1 mV threshold at a PMT gain of 2×105. These results confirm that the PMT performance meets the WCDA++ requirements.

Testing the Yukawa couplings of the Higgs boson to quarks and leptons is important to understand the origin of fermion masses. These proceedings will review several measurements of Higgs boson decays to two bottom quarks or two tau leptons, searches for Higgs boson decays to two charm quarks or two muons, as well as direct constraints on the charm-Yukawa coupling. The production of Higgs boson in association with top quarks will also be discussed. These analyses are based on 139 fb$^{-1}$ of Run-2 data from proton-proton collisions collected by the ATLAS experiment at the Large Hadron Collider (LHC) with a center-of-mass energy of 13 TeV.

Multimodal Data for Adverse Detection using Semi Generative Algorithm

We report on the excitation function of anti-baryon to baryon ratios ($\overline{p}/p$, {\alam /\lam} and {\axi / \xim}) in $pp$ collisions at {\sqrts} = 0.9, 2.76, 7 TeV from DPMJET-III, Pythia~8, EPOS~1.99, and EPOS-LHC model simulations. To study the predictions of these models at {\sqrts} = 13.6 TeV. The anti-baryon to baryon ratios are extremely important for the study of baryon number transport mechanisms. These ratios help determine the carriers of the baryon number and in the extraction of baryon structure information. Even though all models show a good agreement between model simulations and data, the ratios extracted from DPMJET-III model closely describes data at all energies. It is observed that these ratios converge to unity for various model predictions. This convergence also indicates that the anti-baryon to baryon ratios follow the mass hierarchy, such that the hyperon specie containing more strange quarks ({\alam /\lam} and {\axi / \xim}) approaches unity faster than specie containing fewer strange quarks ($\overline{p}/p$). It is also observed that the $\overline{B}/B$ ratio approaches unity more rapidly with the increase in {\sqrts} energy. At lower energies we observe an excess production of baryons over anti-baryons. However, this effect vanishes at higher energies due to the baryon-anti-baryon pair production and the baryon-anti-baryon yield becomes equal. Using model simulations, we additionally compute the asymmetry, ($A\equiv\frac{N_{p}-N_{\bar{p}}}N_{p}+N_{\bar{p}}}$) for protons. The asymmetry shows a decreasing trend with increase in energy from 0.9 to 7 TeV for all energies. This asymmetry trend is confirmed by model predictions at {\sqrts} = 13.6 TeV which will help to put possible constraints on model calculations at {\sqrts} = 13.6 TeV once the Run-III data for LHC becomes available.