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S. Hou

Publications and source records attributed to S. Hou.

30 records · Page 2Linked to original sources
arXiv2020

Design and hardware evaluation of the optical-link system for the ATLAS Liquid Argon Calorimeter Phase-II Upgrade

An optical link system is being developed for the ATLAS Liquid Argon Calorimeter Phase-II upgrade. The optical link system is responsible for transmit the data of over 182 thousand detector channels from 1524 Front-End Boards (FEBs) through 26 optical fibers per FEB over 150 meters to the counting room and brings clocks, bunch crossing reset signals and slow control/monitoring signals back to the FEBs. The optical link system is based on the Low-Power GigaBit Transceivers (lpGBTs) and the Versatile optical Transceiver (VTRx+) modules, which both are being developed for the High-Luminosity LHC upgrade. An evaluation board is designed and the major functions of the optical link system are being evaluated. The design of the optical link system and the evaluation of major functions are presented in the paper.

physics.ins-det↗
arXiv2020

Prototyping of a 25 Gbps optical transmitter for applications in high-energy physics experiments

Development of optical links with 850 nm multi-mode vertical-cavity surface-emitting lasers (VCSELs) has advanced to 25 Gbps in speed. For applications in high-energy experiments, the transceivers are required to be tolerant in radiation and particle fields. We report on prototyping of a miniature transmitter named MTx+, which is developed for high speed transmission with the dual-channel laser driver LOCld65 and 850 nm VCSELs packaged in TOSA format. The LOCld65 is fabricated in the TSMC 65 nm process and is packaged in the QFN-40 for assembly. The MTx+ modules and test kits were first made with PCB and components qualified for 10 Gbps applications, and were tested for achieving 14 Gbps. The data transfer rate of the MTx+ module is investigated further for the speed of up to 25 Gbps. The LOCld65 is examined with post-layout simulation and the module design upgraded with components including the TOSA qualified for 25 Gbps applications. The PCB material is replaced by the Panasonic MEGTRON6. The revised MTx+ is tested at 25 Gbps and the eye-diagram shows a mask margin of 22 %.

physics.ins-det↗
arXiv2018

Impact of the $^7$Be($α, γ$)$^{11}$C reaction on the primordial abundance of $^7$Li

We calculate the radiative capture cross section for $^7$Be($α, γ$)$^{11}$C and its reaction rate of relevance for the big bang nucleosynthesis. The impact of this reaction on the primordial $^7$Li abundance is revised including narrow and broad resonances in the pertinent energy region. Our calculations show that it is unlikely that very low energy resonances in $^{11}$C of relevance for the big bang nucleosynthesis would emerge within a two-body potential model. Based on our results and a comparison with previous theoretical and experimental analyses, we conclude that the impact of this reaction on the so-called "cosmological lithium puzzle" is completely irrelevant.

nucl-th↗
arXiv2016

Hydrolytic degradation of ROMP thermosetting materials catalysed by bio-derived acids and enzyme: from network to linear materials

This paper reports the first example of the degradable ROMP thermosetting materials catalysed by bio-derived acids and cutinase from Thermobifida cellulosilytica (Thc_Cut1). The ROMP thermosetting materials are based on norbornene dicarboximides containing acetal ester groups only in the crosslink moiety. The insoluble cross-linked materials were subjected to acid-catalysed hydrolysis using bio-derived acetic and citric acids as well as enzymatic degradation using Thc_Cut1, resulting in the materials becoming completely soluble in dichloromethane. 1H NMR and rheological analysis performed on materials after acid-catalysed hydrolysis showed characteristics indistinguishable to that of the linear polymer analogues. These analyses confirmed the cleavage of the crosslink moiety upon degradation with the main backbone chains remaining intact. The glass transition temperatures of the polymer materials after acid-catalysed hydrolysis were the same of those observed for the linear polymer analogue. TGA showed that the cross-linked polymers thermally stable to 150 °C, beyond which showed weight losses due to the thermal cleavage of the acetal ester linkages.

cond-mat.mtrl-sci↗
arXiv2015

Theoretical study of the elastic and thermodynamic properties of Pt$_{3}$Al with the L1$_{2}$ structure under high pressure

In this work, the elastic and thermodynamic properties of Pt$_{3}$Al under high pressure are investigated using density functional theory within the generalized gradient approximation. The results of bulk modulus and elastic constants at zero pressure are in good agreement with the available theoretical and experimental values. Under high pressure, all the elastic constants meet the corresponding mechanical stability criteria, meaning that Pt$_{3}$Al possesses mechanical stability. In addition, the elastic constants and elastic modulus increase linearly with the applied pressure. According to the Poisson's ratio $ν$ and elastic modulus ratio ($B/G$), Pt$_{3}$Al alloy is found to be ductile, and higher pressure can significantly enhance the ductility. Those indicate that the elastic properties of Pt$_{3}$Al will be improved under high pressure. Through the quasi-harmonic Debye model, we first successfully report the variations of the Debye temperature $Θ_\textrm{D}$, specific heats $C_{P}$, thermal expansion coefficient $α$, and Grüneisen parameter $γ$ under pressure range from 0 to 100 GPa and temperature range from 0 to 1000 K.

cond-mat.mtrl-sci↗
arXiv2015

JUNO Conceptual Design Report

The Jiangmen Underground Neutrino Observatory (JUNO) is proposed to determine the neutrino mass hierarchy using an underground liquid scintillator detector. It is located 53 km away from both Yangjiang and Taishan Nuclear Power Plants in Guangdong, China. The experimental hall, spanning more than 50 meters, is under a granite mountain of over 700 m overburden. Within six years of running, the detection of reactor antineutrinos can resolve the neutrino mass hierarchy at a confidence level of 3-4$σ$, and determine neutrino oscillation parameters $\sin^2θ_{12}$, $Δm^2_{21}$, and $|Δm^2_{ee}|$ to an accuracy of better than 1%. The JUNO detector can be also used to study terrestrial and extra-terrestrial neutrinos and new physics beyond the Standard Model. The central detector contains 20,000 tons liquid scintillator with an acrylic sphere of 35 m in diameter. $\sim$17,000 508-mm diameter PMTs with high quantum efficiency provide $\sim$75% optical coverage. The current choice of the liquid scintillator is: linear alkyl benzene (LAB) as the solvent, plus PPO as the scintillation fluor and a wavelength-shifter (Bis-MSB). The number of detected photoelectrons per MeV is larger than 1,100 and the energy resolution is expected to be 3% at 1 MeV. The calibration system is designed to deploy multiple sources to cover the entire energy range of reactor antineutrinos, and to achieve a full-volume position coverage inside the detector. The veto system is used for muon detection, muon induced background study and reduction. It consists of a Water Cherenkov detector and a Top Tracker system. The readout system, the detector control system and the offline system insure efficient and stable data acquisition and processing.

physics.ins-det↗
arXiv2012

Studies on fast triggering and high precision tracking with Resistive Plate Chambers

We report on studies of fast triggering and high-precision tracking using Resistive Plate Chambers (RPCs). Two beam tests were carried out with the 180 GeV muon beam at CERN using RPCs with gas gaps of 1.00 or 1.15 mm and equipped with readout strips with 1.27 mm pitch. This is the first beam test of RPCs with fine-pitch readout strips that explores simultaneously precision tracking and triggering capabilities. RPC signals were acquired with precision timing and charge integrating readout electronics at both ends of the strips. The time resolution was measured to be better than 600 ps and the average spatial resolution was found to be 220 um using charge information and 287 um using timing information. The dual-ended readout allows the determination of the average and the difference of the signal arrival times. The average time was found to be independent of the incident particle position along the strip and is useful for triggering purposes. The time difference yielded a determination of the hit position with a precision of 7.5 mm along the strip. These results demonstrate the feasibility using RPCs for fast and high-resolution triggering and tracking.

physics.ins-det↗
arXiv2006

Data processing model for the CDF experiment

The data processing model for the CDF experiment is described. Data processing reconstructs events from parallel data streams taken with different combinations of physics event triggers and further splits the events into datasets of specialized physics datasets. The design of the processing control system faces strict requirements on bookkeeping records, which trace the status of data files and event contents during processing and storage. The computing architecture was updated to meet the mass data flow of the Run II data collection, recently upgraded to a maximum rate of 40 MByte/sec. The data processing facility consists of a large cluster of Linux computers with data movement managed by the CDF data handling system to a multi-petaByte Enstore tape library. The latest processing cycle has achieved a stable speed of 35 MByte/sec (3 TByte/day). It can be readily scaled by increasing CPU and data-handling capacity as required.

physics.ins-det↗
arXiv2006

Data production models for the CDF experiment

The data production for the CDF experiment is conducted on a large Linux PC farm designed to meet the needs of data collection at a maximum rate of 40 MByte/sec. We present two data production models that exploits advances in computing and communication technology. The first production farm is a centralized system that has achieved a stable data processing rate of approximately 2 TByte per day. The recently upgraded farm is migrated to the SAM (Sequential Access to data via Metadata) data handling system. The software and hardware of the CDF production farms has been successful in providing large computing and data throughput capacity to the experiment.

physics.data-an↗
arXiv2006

Data production of a large Linux PC Farm for the CDF experiment

The data production farm for the CDF experiment is designed and constructed to meet the needs of the Run II data collection at a maximum rate of 20 MByte/sec during the run. The system is composed of a large cluster of personal computers (PCs) with a high-speed network interconnect and a custom design control system for the flow of data and the scheduling of tasks on this PC farm. The farm explores and exploits advances in computing and communication technology. The data processing has achieved a stable production rate of approximately 2 TByte per day. The software and hardware of the CDF production farms has been successful in providing large computing and data throughput capacity to the experiment.

hep-ex↗
arXiv1994

A Lattice Boltzmann Subgrid Model for High Reynolds Number Flows

A subgrid turbulence model for the lattice Boltzmann method is proposed for high Reynolds number fluid flow applications. The method, based on the standard Smagorinsky subgrid model and a single-time relaxation lattice Boltzmann method, incorporates the advantages of the lattice Boltzmann method for handling arbitrary boundaries and is easily implemented on parallel machines. The method is applied to a two-dimensional driven cavity flow for studying dynamics and the Reynolds number dependence of the flow structures. The substitution of other subgrid models, such as the dynamic subgrid model, in the framework of the LB method is discussed.

comp-gas↗