arXiv subjects

Y. C. Lin

Publications and source records attributed to Y. C. Lin.

At least 19 recordsLinked to original sources

arXiv2016

Measurement of Cosmic-ray Muons and Muon-induced Neutrons in the Aberdeen Tunnel Underground Laboratory

We have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be $I_μ = (5.7 \pm 0.6) \times 10^{-6}$ cm$^{-2}$s$^{-1}$sr$^{-1}$. The yield of muon-induced neutrons in the liquid scintillator was determined to be $Y_{n} = (1.19 \pm 0.08 (stat) \pm 0.21 (syst)) \times 10^{-4}$ neutrons/($μ\cdot$g$\cdot$cm$^{-2}$). A fit to the recently measured neutron yields at different depths gave a mean muon energy dependence of $\left\langle E_μ \right\rangle^{0.76 \pm 0.03}$ for liquid-scintillator targets.

physics.ins-det↗

arXiv2016

Development of a Bonner Sphere Neutron Spectrometer from a Commercial Neutron Dosimeter

Bonner Spheres have been used widely for the measurement of neutron spectra with neutron energies ranged from thermal up to at least 20 MeV. A Bonner Sphere neutron spectrometer (BSS) was developed by extending a Berthold LB 6411 neutron-dose-rate meter. The BSS consists of a $^{3}$He thermal-neutron detector with integrated electronics, a set of eight polyethylene spherical shells and two optional lead shells of various sizes. The response matrix of the BSS was calculated with GEANT4 Monte Carlo simulation. The BSS had a calibration uncertainty of $\pm 8.6\%$ and a detector background rate of $(1.57 \pm 0.04) \times 10^{-3}$ s$^{-1}$. A spectral unfolding code NSUGA was developed. The NSUGA code utilizes genetic algorithms and has been shown to perform well in the absence of a priori information.

physics.ins-det↗

arXiv2016

The Radon Monitoring System in Daya Bay Reactor Neutrino Experiment

We developed a highly sensitive, reliable and portable automatic system (H$^{3}$) to monitor the radon concentration of the underground experimental halls of the Daya Bay Reactor Neutrino Experiment. H$^{3}$ is able to measure radon concentration with a statistical error less than 10\% in a 1-hour measurement of dehumidified air (R.H. 5\% at 25$^{\circ}$C) with radon concentration as low as 50 Bq/m$^{3}$. This is achieved by using a large radon progeny collection chamber, semiconductor $α$-particle detector with high energy resolution, improved electronics and software. The integrated radon monitoring system is highly customizable to operate in different run modes at scheduled times and can be controlled remotely to sample radon in ambient air or in water from the water pools where the antineutrino detectors are being housed. The radon monitoring system has been running in the three experimental halls of the Daya Bay Reactor Neutrino Experiment since November 2013.

physics.ins-det↗

arXiv2013

An apparatus for studying spallation neutrons in the Aberdeen Tunnel laboratory

In this paper, we describe the design, construction and performance of an apparatus installed in the Aberdeen Tunnel laboratory in Hong Kong for studying spallation neutrons induced by cosmic-ray muons under a vertical rock overburden of 611 meter water equivalent (m.w.e.). The apparatus comprises of six horizontal layers of plastic-scintillator hodoscopes for determining the direction and position of the incident cosmic-ray muons. Sandwiched between the hodoscope planes is a neutron detector filled with 650 kg of liquid scintillator doped with about 0.06% of Gadolinium by weight for improving the efficiency of detecting the spallation neutrons. Performance of the apparatus is also presented.

physics.ins-det↗

arXiv2008

Crumpling wires in two dimensions

An energy-minimal simulation is proposed to study the patterns and mechanical properties of elastically crumpled wires in two dimensions. We varied the bending rigidity and stretching modulus to measure the energy allocation, size-mass exponent, and the stiffness exponent. The mass exponent is shown to be universal at value $D_{M}=1.33$. We also found that the stiffness exponent $α=-0.25$ is universal, but varies with the plasticity parameters $s$ and $θ_{p}$. These numerical findings agree excellently with the experimental results.

cond-mat.soft↗

arXiv2008

Crumpling under an ambient pressure

A pressure chamber is designed to study the crumpling process under an ambient force. The compression force and its resulting radius for the ball obey a power law with an exponent that is independent of the thickness and initial size of the sheet. However, the exponent is found to be material-dependent and less than the universal value, 0.25, claimed by the previous simulations. The power law behavior disappears at high pressure when the compressibility drops discontinuously, which is suggestive of a jammed state.

cond-mat.soft↗

arXiv2007

Circular invasion of fluid into a quenched disordered media

The Hele-Shaw experiment is performed with a circular invasion to study the scaling and dynamic behavior of the interface. We did not find any universal power law. The time exponent varies with the range of scale, as has been reported in the literature but not captured by existing models. We ascribe this distinct difference from the planar injection to the fact that our interface size grows with time. This renders the old geometries being constantly pushed apart to leave rooms for new features. As a result, the amplitude of the interface spectrum will decrease with the angular momentum, different from that of a white noise commonly assumed for the planar injection. Due to the moving boundary, the existing Kardar-Parisi-Zhang and Edwards-Wilkinson (EW) equations can no longer be applied. We propose a modified EW equation that not only conserves the fluid volume, but is also capable of predicting all the above features. Two phenomenological coefficients are introduced to represent the competing trend of instability and smoothness. Their dependence on the microscopic parameters are determined from dimensional arguments, and their estimated values conform with the experiments.

cond-mat.dis-nn↗

arXiv2004

Experimental Realization of an NMR Quantum Switch

In this paper, we report an experimental realization of quantum switch using nuclear spins and magnetic resonant pulses. The nuclear spins of H and C in carbon-13 labelled chloroform are used to carry the information, then nuclear magnetic resonance pulses are applied to perform either bypass or cross function to achieve the switching. Compared with a traditional space or time domain switch, this switching architecture is much more scalable, therefore a high throughput switching device can be built simply by increasing the number of I/O ports. In addition, it can be used not only as a device to switch classical information, but also a building block of quantum information networks.

quant-ph↗

arXiv2001

Day-Scale Variability of 3C 279 and Searches for Correlations in Gamma-Ray, X-Ray, and Optical Bands

Light curves of 3C 279 are presented in optical (R-band), X-rays (RXTE/PCA), and gamma rays (CGRO/EGRET) for 1999 Jan-Feb and 2000 Jan-Mar. During both of those epochs the gamma-ray levels were high, and all three observed bands demonstrated substantial variation, on time scales as short as one day. Correlation analyses provided no consistent pattern, although a rather significant optical/gamma-ray correlation was seen in 1999, with a gamma-ray lag of ~2.5 days, and there are other suggestions of correlations in the light curves. For comparison, correlation analysis is also presented for the gamma-ray and X-ray light curves during the large gamma ray flare in 1996 Feb and the two gamma-bright weeks leading up to it; the correlation at that time was strong, with a gamma-ray/X-ray offset of no more than 1 day.

astro-ph↗

arXiv1999

EGRET Spectral Index and the Low-Energy Peak Position in the Spectral Energy Distribution of EGRET-Detected Blazars

In current theoretical models of the blazar subclass of active galaxies, the broadband emission consists of two components: a low-frequency synchrotron component with a peak in the IR to X-ray band, and a high-frequency inverse Compton component with a peak in the gamma-ray band. In such models, the gamma-ray spectral index should be correlated with the location of the low-energy peak, with flatter gamma-ray spectra expected for blazars with synchrotron peaks at higher photon energies and vice versa. Using the EGRET-detected blazars as a sample, we examine this correlation and possible uncertainties in its construction.

astro-ph↗

arXiv1999

Beam Test of Gamma-ray Large Area Space Telescope Components

A beam test of GLAST (Gamma-ray Large Area Space Telescope) components was performed at the Stanford Linear Accelerator Center in October, 1997. These beam test components were simple versions of the planned flight hardware. Results on the performance of the tracker, calorimeter, and anti-coincidence charged particle veto are presented.

physics.ins-det↗

arXiv1997

SU(3) breaking and baryon magnetic moments

We show that the magnetic moments of the octet baryons can be fitted to an accuracy of 1.5 percent by a phenomenological Lagrangian in which SU(3) breaking corrections appear only linearly. This is in contrast to conventional chiral perturbation theory in which corrections non-analytic in SU(3) breaking dominate and tend to spoil the agreement with the data. Motivated by this observation, we propose a modified scheme for chiral perturbation theory that gives rise to a similar linear breaking of SU(3) symmetry. (Pacs 13.40.Em, 14.20.-c, 11.30.Rd)

hep-ph↗

arXiv1996

Heavy-baryon chiral perturbation theory and reparametrization invariance

We examine the constraints imposed by reparametrization invariance on heavy-baryon chiral perturbation theory (HBChPT). We study the case of 3 flavors and consider both the strong and weak ($|ΔS| =1$) interaction sector. Some of the parameters in the HBChPT Lagrangian are fixed as a consequence of reparametrization invariance. We discuss the consequences for the calculation of hyperon weak radiative decays in HBChPT.

hep-ph↗

arXiv1996

Study of Long Distance Contributions to $K\to nπν\barν$

We calculate long distance contributions to $K\toπν\barν\,,\ ππν\barν$, and $πππν\barν$ modes within the framework of chiral perturbation theory. We find that these contributions to decay rates of $K\to πν\barν$ and $K\to ππν\barν$ in the chiral logarithmic approximation are at least seven orders of magnitude suppressed relative to those from the short distance parts. The long distance effects in this class of decays are therefore negligible.

hep-ph↗

arXiv1996

Hyperon weak radiative decays in chiral perturbation theory

We investigate the leading-order amplitudes for weak radiative decays of hyperons in chiral perturbation theory. We consistently include contributions from the next-to-leading order weak-interaction Lagrangian. It is shown that due to these terms Hara's theorem is violated. The data for the decays of charged hyperons can be easily accounted for. However, at this order in the chiral expansion, the four amplitudes for the decays of neutral hyperons satisfy relations which are in disagreement with the data. The asymmetry parameters for all the decays can not be accounted for without higher-order terms. We shortly comment on the effect of the 27-plet part of the weak interaction.

hep-ph↗

arXiv1995

Renormalization of $K^+ K^- \to π^0π^+π^-$

We derive the vertices of five-meson and seven-meson anomaly processes from the four dimensional expansion form of Wess-Zumino term. Using these vertices we calculate the amplitude, both the finite part and divergent part, of {$K^+ K^- \rightarrow π^0 π^+ π^-$} to one loop and renormalize the lagrangian. The divergent part agrees with the result derived from path integral approach. Contribution from counter terms is estimated by using the vector meson dominance model. Test of the vertex in the $t$-channel of $K^- P\rightarrowΣ^0π^0π^+π^-$ near the threshold is discussed. We find that the amplitudes arising from chiral loop and counter terms are of opposite sign and the counter term amplitude is about twice the loop amplitude.

hep-ph↗

arXiv1995

Comments on long distance contribution to $K^+\toπ^+ν\barν$

We study the long distance contribution to $K^+\toπ^+ν\bar{ν$ by using chiral perturbation theory. We find that the tree level $O(P^2)$ contribution vanishes identically without assuming the large $N_c$ limit. The leading contribution arises from the one-loop amplitude, which is $O(P^4)$ in the chiral power counting. The branching ratio of the long distance contribution is found to be of order $10^{-7}$ smaller compared with that of short distance one and hence is completely negligible.

hep-ph↗

arXiv1994

Baryon Chiral Perturbation Theory up to Next-to-Leading Order

We examine the general lagrangian for baryon chiral perturbation theory with SU(3) flavor symmetry, up to the next-to-leading order. We consider both the strong and the weak interaction. The inverse of the baryon mass is treated as an additional small expansion parameter, and heavy fermion effective field theory techniques are employed to provide a consistent expansion scheme. A detailed account is given on the restrictions imposed on the lagrangian by the various symmetries. Corrections due to the finite baryon mass are also discussed.

hep-ph↗