arXiv subjects

Lijie Sun

Publications and source records attributed to Lijie Sun.

4 recordsLinked to original sources

arXiv2025

The Least Action-Augmented Lanchester Model

The principle of least action, a fundamental principle in variational mechanics with broad applicability to classical physical systems, is employed to formulate a novel attrition model for combat dynamics. This formulation extends the Lanchester's square law through second-order temporal derivatives by requiring the resultant Euler-Lagrange equation to coincide with the classical Lanchester's equation. Initial conditions at a specified temporal point enable determination of subsequent system evolution through action minimization, while terminal boundary conditions permit backward reconstruction of combat trajectories. The model's validity is examined through historical analysis of WWII engagements: the Battle of Kursk and the Battle of Iwo Jima. Comparative studies with conventional Lanchester's square models demonstrate marked improvements in predictive accuracy regarding force strength progression, particularly in capturing non-linear attrition patterns characteristic of prolonged engagements.

physics.soc-ph↗

arXiv2025

$\beta$-delayed proton pandemonium: A first detailed $^{31}$Cl($\beta p \gamma$)$^{30}$P decay scheme

Positron decays of proton-rich nuclides exhibit large $Q$ values, producing complex cascades which frequently involve various radiations, including protons and $\gamma$ rays. Often, only one of the two is measured in a single experiment, limiting the accuracy and completeness of the decay scheme. An example is $^{31}$Cl, for which protons and $\gamma$ rays have been measured separately in detail but never with substantial sensitivity to proton-$\gamma$ coincidences. We provide detailed measurements of $^{31}$Cl $\beta$-delayed proton decay including $\beta$-$p$-$\gamma$ sequences, extract spectroscopic information on $^{31}$S excited states as well as their $\beta^+$ feedings, and compare to shell-model calculations. A fast fragmented beam of $^{31}$Cl provided by the National Superconducting Cyclotron Laboratory (NSCL) was deposited in the Gaseous Detector with Germanium Tagging (GADGET) system. GADGET's gas-filled Proton Detector was used to detect $\beta$-delayed protons, and the Segmented Germanium Array (SeGA) was used to detect $\beta$-delayed $\gamma$ rays. As many as 20 previously unobserved $\beta$-delayed proton transitions are reported, most of which populate excited states of $^{30}$P. The first detailed $^{31}$Cl($\beta p \gamma$)$^{30}$P decay scheme is presented, including updated $\beta$-delayed proton energies and intensities, as well as several new $^{31}$S levels. Improved agreement is found with theoretical calculations of the Gamow-Teller strengths $B(\text{GT})$ for $^{31}$S excitation energies $7.5 < E_x < 9.5$ MeV. The present work demonstrates that the ability to detect $\beta$-delayed protons and $\gamma$ rays in coincidence is essential for accurate positron decay schemes to compare with nuclear structure theory. This phenomenon for $\beta$-delayed protons resembles the pandemonium effect originally introduced for $\beta$-delayed $\gamma$ rays.

nucl-ex↗

arXiv2025

On the origin of the E1 electron trap level in GaN and dilute AlxGa1-xN films

The results of high-resolution Laplace deep-level transient spectroscopy (L-DLTS) measurements applied to the E1 and FeGa electron traps in dilute AlxGa1-xN films (x = 0.063), grown by metal-organic vapor phase epitaxy (MOVPE) on Ammono-GaN substrates, are presented. It is shown that the electron emission signals associated with the E1 donor and the FeGa acceptor levels split into individual components due to the aluminium fluctuations in the nearest neighbour shells around the E1 and FeGa defects. The splitting patterns observed in the L-DLTS spectra are nearly identical for both signals. Furthermore, the ratios of peak magnitudes determined from the L-DLTS analysis for both the E1 and E3 traps are consistent with calculated probabilities of finding a given number of aluminium atoms in the second nearest neighbour shell around a Ga lattice site in AlxGa1-xN with x = 0.063. These findings provide strong evidence that both the E1 and the FeGa trap states in dilute AlxGa1-xN are related to defects located in the Ga sublattice. To elucidate the origin of the E1 trap in AlxGa1-xN, we have performed a comprehensive scan of possible impurities and defects in GaN and AlxGa1-xN using hybrid density functional calculations of transition levels and their associated shifts upon substitution of Ga neighbour atoms by Al. From analysis of the results, we find that the E1 electron trap in GaN and AlxGa1-xN is most likely related to a donor transition from a carbon or molybdenum impurity atom at the gallium site, respectively.

cond-mat.mtrl-sci↗

arXiv2014

Development of large-area quadrant silicon detector for charged particles

The quadrant silicon detector, a kind of passivated implanted planar silicon detector with quadrant structure on the junction side, gained its wide application in charged particle detection. In this paper, the manufacturing procedure, performance test and results of the quadrant silicon detector developed recently at the China Institute of Atomic Energy are presented. The detector is about 300 $μ$m thick with a 48$\times$48 mm$^{2}$ active area. The leakage current under full depletion bias voltage of -16 V is about 2.5 nA, and the raising time is better than 160 ns. The energy resolution for 5.157 MeV $α$-particle is around the level of $1\%$. Charge sharing effects between the neighboring quads, leading to complicated correlations between two quads, were observed when $α$ particles illuminated on the junction side. It is explained as a result of distortion of electric field of inter-quad region. Such events is only about $0.6\%$ of all events and can be neglected in an actual application.

physics.ins-det↗