Engineering topics

Chang, J. F.

Publications and source records attributed to Chang, J. F..

70 records · Page 4

DOE OSTI2024

Precision measurement of the branching fraction of J / ψ → K + K − via ψ ( 2 S ) → π + π − J / ψ

Using a sample of 448.1 × 10 6 ψ ( 2 S ) events collected with the BESIII detector, we perform a study of the decay J / ψ → K + K − via ψ ( 2 S ) → π + π − J / ψ . The branching fraction of J / ψ → K + K − is determined to be B K + K − = ( 3.072 ± 0.023 ( stat ) ± 0.050 ( syst ) ) × 10 − 4 , which is consistent with previous measurements but with significantly improved precision. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Study of e + e − → π + π − π 0 at s from 2.00 to 3.08 GeV at BESIII

With the data samples taken at center-of-mass energies from 2.00 to 3.08 GeV with the BESIII detector at the BEPCII collider, a partial wave analysis on the e + e − → π + π − π 0 process is performed. The Born cross sections for e + e − → π + π − π 0 and its intermediate processes e + e − → ρ π and ρ ( 1450 ) π are measured as functions of s . The results for e + e − → π + π − π 0 are consistent with previous results measured with the initial state radiation method within one standard deviation, and improve the uncertainty by a factor of ten. By fitting the line shapes of the Born cross sections for the e + e − → ρ π and e + e − → ρ ( 1450 ) π , a structure with mass M = 2119 ± 11 ± 15 MeV / c 2 and width Γ = 69 ± 30 ± 5 MeV is observed with a significance of 5.9 σ , where the first uncertainties are statistical and the second ones are systematic. This structure can be interpreted as an excited ω state. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for diphoton decays of an axionlike particle in radiative J / ψ decays

We search for the diphoton decay of a light pseudoscalar axionlike particle, a , in radiative J / ψ decays, using 10 10 J / ψ events collected with the BESIII detector. We find no evidence of a signal and set upper limits at the 95% confidence level on the product branching fraction B ( J / ψ → γ a ) × B ( a → γ γ ) and the axionlike particle photon coupling constant g a γ γ in the ranges of ( 3.7 – 48.5 ) × 10 − 8 and ( 2.2 – 101.8 ) × 10 − 4 GeV − 1 , respectively, for 0.18 ≤ m a ≤ 2.85 GeV / c 2 . These are the most stringent limits to date in this mass region. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for a Sub-eV Sterile Neutrino Using Daya Bay’s Full Dataset

This Letter presents results of a search for the mixing of a sub-eV sterile neutrino with three active neutrinos based on the full data sample of the Daya Bay Reactor Neutrino Experiment, collected during 3158 days of detector operation, which contains 5.55 × 106 reactor $\overline{v}$ e candidates identified as inverse beta-decay interactions followed by neutron capture on gadolinium. The analysis benefits from a doubling of the statistics of our previous result and from improvements of several important systematic uncertainties. No significant oscillation due to mixing of a sub-eV sterile neutrino with active neutrinos was found. Exclusion limits are set by both Feldman-Cousins and CLs methods. Light sterile neutrino mixing with sin 2⁡ 2⁢θ 14 ≳ 0.01 can be excluded at 95% confidence level in the region of 0.01 eV 2 ≲ |Δ⁢$m$$^{2}_{41}$| ≲ 0.1 eV 2 . This result represents the world-leading constraints in the region of 2 × 10 –4 eV 2 ≲ |Δ⁢$m$$^{2}_{41}$| ≲ 0.2 eV 2 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Search for the radiative transition χ c 1 ( 3872 ) → γ ψ 2 ( 3823 )

Using 9.0 f b − 1 of e + e − collision data collected at center-of-mass energies from 4.178 to 4.278 GeV with the BESIII detector at the BEPCII collider, we perform the first search for the radiative transition χ c 1 ( 3872 ) → γ ψ 2 ( 3823 ) . No signal is observed and the upper limit on the ratio of branching fractions B ( χ c 1 ( 3872 ) → γ ψ 2 ( 3823 ) , ψ 2 ( 3823 ) → γ χ c 1 ) / B ( χ c 1 ( 3872 ) → π + π − J / ψ ) is set at 0.075 at the 90% confidence level. Our result contradicts theoretical predictions under the assumption that the χ c 1 ( 3872 ) is the pure charmonium state χ c 1 ( 2 P ) . Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

First measurement of the yield of 8 He isotopes produced in liquid scintillator by cosmic-ray muons at Daya Bay

Here, Daya Bay presents the first measurement of cosmogenic 8 He isotope production in liquid scintillator, using an innovative method for identifying cascade decays of 8 He and its child isotope, 8 Li. We also measure the production yield of 9 Li isotopes using well-established methodology. The results, in units of 10 –8 μ –1 ⁢g –1 cm 2 , are 0.307 ± 0.042, 0.341 ± 0.040, and 0.546 ± 0.076 for 8 He, and 6.73 ± 0.73, 6.75 ± 0.70, and 13.74 ± 0.82 for 9 Li at average muon energies of 63.9 GeV, 64.7 GeV, and 143.0 GeV, respectively. The measured production rate of 8 He isotopes is more than an order of magnitude lower than any other measurement of cosmogenic isotope production. It replaces the results of previous attempts to determine the ratio of 8 He to 9 Li production that yielded a wide range of limits from 0% to 30%. The results provide future liquid-scintillator-based experiments with improved ability to predict cosmogenic backgrounds.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

Evidence of the h c → K S 0 K + π − + c . c . decay

Based on ( 2.712 ± 0.014 ) × 10 9 ψ ( 3686 ) events collected by the BESIII Collaboration, evidence of the hadronic decay h c → K S 0 K + π − + c . c . is found with a significance of 4.3 σ in the ψ ( 3686 ) → π 0 h c process. The branching fraction of h c → K S 0 K + π − + c . c . is measured to be ( 7.3 ± 1.8 ± 0.8 ) × 10 − 4 , where the first and second uncertainties are statistical and systematic, respectively. Combining with the exclusive decay width of η c → K K ¯ π , our result indicates inconsistencies with both pQCD and NRQCD predictions. Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Study of e + e − → ω X ( 3872 ) and γ X ( 3872 ) from 4.66 to 4.95 GeV

Using data samples with an integrated luminosity of 4.5 fb − 1 collected by the BESIII detector at center-of-mass energies ranging from 4.66 GeV to 4.95 GeV, we study the processes of e + e − → ω X ( 3872 ) and e + e − → γ X ( 3872 ) . With the e + e − → ω X ( 3872 ) process, the branching fraction ratio R ≡ B ( X ( 3872 ) → γ J / ψ ) B ( X ( 3872 ) → π + π − J / ψ ) is measured to be 0.38 ± 0.2 0 stat ± 0.0 1 syst ( R < 0.83 at 90% confidence level). In addition, we measure the ratio of the average cross section of e + e − → ω X ( 3872 ) to e + e − → ω χ c 1 ( ω χ c 2 ) to be σ ω X ( 3872 ) / σ ω χ c 1 ( σ ω X ( 3872 ) / σ ω χ c 2 ) = 5.2 ± 1.0 stat ± 1.9 syst ( 5.5 ± 1.1 stat ± 2.4 syst ) . Finally, we search for the process of e + e − → γ X ( 3872 ) , and no obvious signal is observed. The upper limit on the ratio of the average cross section of e + e − → γ X ( 3872 ) to e + e − → ω X ( 3872 ) is set as σ γ X ( 3872 ) / σ ω X ( 3872 ) < 0.23 at 90% confidence level. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for the leptonic decays D * + → e + ν e and D * + → μ + ν μ

We present the first search for the leptonic decays D * + → e + ν e and D * + → μ + ν μ by analyzing a data sample of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, corresponding to an integrated luminosity of 6.32 fb − 1 . No significant signal is observed. The upper limits on the branching fractions for D * + → e + ν e and D * + → μ + ν μ are set to be 1.1 × 10 − 5 and 4.3 × 10 − 6 at 90% confidence level, respectively. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Measurements of Normalized Differential Cross Sections of Inclusive η Production in e + e − Annihilation at Energy from 2.0000 to 3.6710 GeV

Using data samples collected with the BESIII detector operating at the BEPCII storage ring, the cross section of the inclusive process e + e − → η + X , normalized by the total cross section of e + e − → hadrons , is measured at eight center-of-mass energy points from 2.0000 to 3.6710 GeV. These are the first measurements with momentum dependence in this energy region. Our measurement shows a significant discrepancy compared to the existing fragmentation functions. To address this discrepancy, a new QCD analysis is performed at the next-to-next-to-leading order with hadron mass corrections and higher twist effects, which can explain both the established high-energy data and our measurements reasonably well. Published by the American Physical Society 2024

Physics↗

NASA NTRS1993

ROCSAT-1 telecommunication experiments

This paper addresses a telecommunication payload project approved by the R.O.C. NSPO's ROCSAT-1 space program. This project will enable several innovative experiments via the low-earth-orbit satellite ROCSAT-1, including multipath fading channel characterization, ionospheric scintillation measurement, real-time voice communications, and CDMA data communications. A unified L/S-band transponder payload is proposed for conducting these experiments in an efficient way. The results of these experiments would provide the evolving mobile communication communities with fruitful information.

Chang, J. F.↗

NASA NTRS1987

TRANDESNF: A computer program for transonic airfoil design and analysis in nonuniform flow

The use of a transonic airfoil code for analysis, inverse design, and direct optimization of an airfoil immersed in propfan slipstream is described. A summary of the theoretical method, program capabilities, input format, output variables, and program execution are described. Input data of sample test cases and the corresponding output are given.

Chang, J. F.↗

NASA NTRS1986

Transonic airfoil analysis and design in nonuniform flow

A nonuniform transonic airfoil code is developed for applications in analysis, inverse design and direct optimization involving an airfoil immersed in propfan slipstream. Problems concerning the numerical stability, convergence, divergence and solution oscillations are discussed. The code is validated by comparing with some known results in incompressible flow. A parametric investigation indicates that the airfoil lift-drag ratio can be increased by decreasing the thickness ratio. A better performance can be achieved if the airfoil is located below the slipstream center. Airfoil characteristics designed by the inverse method and a direct optimization are compared. The airfoil designed with the method of direct optimization exhibits better characteristics and achieves a gain of 22 percent in lift-drag ratio with a reduction of 4 percent in thickness.

Chang, J. F.↗

NASA NTRS1983

Calculating the Vortex Lift Effect of Cambered Wings

Computer program VORCAM calculates vortex-lift effect of cambered wings by suction analogy. Based on improved version of Woodward's chord plane aerodynamic panel method for subsonic and superrsonic flow. Developed specifically for cambered wings exhibitig edge-separated vortex flow, including those with leading-edge vortex flaps. Program written in FORTRAN IV.

Lan, C. E.↗

NASA NTRS1981

VORCAM: A computer program for calculating vortex lift effect of cambered wings by the suction analogy

A user's guide to an improved version of Woodward's chord plane aerodynamic panel computer code is presumed. The guide can be applied to cambered wings exhibiting edge separated flow, including those with leading edge vortex flow at subsonic and supersonic speeds. New orientations for the rotated suction force are employed based on the momentum principal. The supersonic suction analogy method is improved by using an effective angle of attack defined through a semiempirical method.

Lan, C. E.↗

NASA NTRS1981

Calculation of vortex lift effect for cambered wings by the suction analogy

An improved version of Woodward's chord plane aerodynamic panel method for subsonic and supersonic flow is developed for cambered wings exhibiting edge separated vortex flow, including those with leading edge vortex flaps. The exact relation between leading edge thrust and suction force in potential flow is derived. Instead of assuming the rotated suction force to be normal to wing surface at the leading edge, new orientation for the rotated suction force is determined through consideration of the momentum principle. The supersonic suction analogy method is improved by using an effective angle of attack defined through a semi-empirical method. Comparisons of predicted results with available data in subsonic and supersonic flow are presented.

Lan, C. E.↗