arXiv subjects

Hu-Shan Xu

Publications and source records attributed to Hu-Shan Xu.

At least 19 recordsLinked to original sources

arXiv2024

A possible explanation of W-type phenomena in V694 Peg

Three sets of complete multi-color light curves of V694 Peg observed in 2013, 2015 and 2019 were presented and analyzed. Our photometric solutions show that this system is an A-type shallow contact binary in 2013 and 2015, while it converted to a W-type one in 2019. A large cool spot on the component of this binary could explain the conversion, implying the W-type phenomena may be caused by magnetic activity of the components. We have collected available data of this binary and calculated 505 times of light minimum, which span 17 years. The orbital period investigation based on these timings shows there is a long-term period increase at a rate of $dP/dt$ = 4.3($\pm$ 0.3)$\times$ 10$^{-9}$ d yr$^{-1}$ superposed on a periodic variation with a period of 11.81($\pm$ 0.06) years. The cyclic orbital variation may be the result of magnetic activity cycles or the existence of a third body. Till now, only 8 transformed systems including V694 Peg have been reported. Compared with other converting contact systems between A-type and W-type, V694 Peg is recorded as the shortest-period one. All of these converting systems are late-type (later than F7) contact binaries with O'Connell effect and show cyclic period variation, which indicates that magnetic activity may be the reason for the conversion between the two types of contact binaries. For investigating the nature of A-type and W-type phenomena, the discovery of more converting contact binaries is essential.

astro-ph.SR↗

arXiv2021

Charge resolution in the isochronous mass spectrometry and the mass of $^{51}$Co

Isochronous mass spectrometry (IMS) of heavyion storage rings is a powerful tool for the mass measurements of short-lived nuclei. In IMS experiments, masses are determined through precision measurements of the revolution times of the ions stored in the ring. However, the revolution times cannot be resolved for particles with nearly the same mass-to-charge (m/q) ratios. To overcome this limitation and to extract the accurate revolution times for such pairs of ion species with very close m/q ratios, in our early work on particle identification, we analyzed the amplitudes of the timing signals from the detector based on the emission of secondary electrons. Here, the previous data analysis method is further improved by considering the signal amplitudes, detection efficiencies, and number of stored ions in the ring. A sensitive Z-dependent parameter is introduced in the data analysis, leading to a better resolution of $^{34}$Ar$^{18+}$ and $^{51}$Co$^{27+}$ with A/Z=17/9. The mean revolution times of $^{34}$Ar$^{18+}$ and $^{51}$Co$^{27+}$ are deduced, although their time difference is merely 1.8 ps. The uncorrected, overlapped peak of these ions has a full width at half maximum of 7.7 ps. The mass excess of $^{51}$Co was determined to be -27332(41) keV, which is in agreement with the previous value of -27342(48) keV.

nucl-ex↗

arXiv2018

Towards the full realization of the RIBLL2 beam line at the HIRFL-CSR complex

The RIBLL2 in-flight separator at IMP, the secondary beam line between two storage rings at the \blue{\uwave{Heavy Ion Research Facility in Lanzhou (HIRFL-CSR)}}, has been commissioned to study the rare-isotope beam (RIB) physics at around 300 MeV/nucleon for the first time, in combination of the external target facility (ETF). The unambiguous particle identification in mass and charge states for $^{18}$O and $^{40}$Ar fragments has been achieved in recent experiments. A full realization of RIBLL2 will open many potentials to address important RIB physics problems at around 300 MeV/nucleon.

physics.acc-ph↗

arXiv2016

Application of Origen2.1 in the decay photon spectrum calculation of spallation products

Origen2.1 is a widely used computer code for calculating the burnup, decay, and processing of radioactive materials. However, the nuclide library of Origen2.1 is used for existing reactors like pressurized water reactor, to calculate the photon spectrum released by the decay of spallation products, we have made specific libraries for the ADS tungsten spallation target, based on the results given by a Monte Carlo code: FLUKA. All the data used to make the Origen2.1 libraries is obtained from Nuclear structure & decay Data (NuDat2.6). The accumulated activity of spallation products and the contribution of nuclides to photon emission are given in this paper.

nucl-th↗

arXiv2016

A data analysis method for isochronous mass spectrometry using two time-of-flight detectors at CSRe

The concept of isochronous mass spectrometry (IMS) applying two time-of-flight (TOF) detectors originated many years ago at GSI. However, the corresponding method for data analysis has never been discussed in detail. Recently, two TOF detectors have been installed at CSRe and the new working mode of the ring is under test. In this paper, a data analysis method for this mode is introduced and tested with a series of simulations. The results show that the new IMS method can significantly improve mass resolving power via the additional velocity information of stored ions. This improvement is especially important for nuclides with Lorentz factor $γ$-value far away from the transition point $γ_t$ of the storage ring CSRe.

physics.ins-det↗

arXiv2015

Analysis of digital timing methods with DRS4 module

A new Digital Pulse Processing (DPP) module has been developed, based on a domino ring sampler version 4 chip (DRS4), with good time resolution for LaBr3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronic and acquisition system to process the output signals from XP20D0 Photomultiplier Tubes (PMTs). Two PMTs were coupled with LaBr3 scintillator and placed face to face on both sides of a radioactive positron 22Na source for 511 keV gama ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps (FWHM), obtained by the digital constant fraction discrimination (dCFD) method, which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography (PET) with time of flight (TOF), as well as for scintillation timing measurement, such as in TOF-DeltaE and TOF-E systems for particle identification, with picosecond accuracy timing measurement. Furthermore, this module is more simple and convenient than other systems.

physics.ins-det↗

arXiv2014

First estimate of producing the charmed baryon $Λ_c(2880)$ at PANDA

In the present work we explore the production potential of $Λ_c(2880)^+$ at PANDA. With the $J^P=\frac{5}{2}^+$ assignment to $Λ_c(2880)^+$, we calculate the differential and total cross sections of $p\bar{p}\to Λ_c^-Λ_c(2880)^+$. We also perform the Dalitz plot analysis and give the $pD^0$ invariant mass spectrum distribution of the process $p\bar{p}\to Λ_c^-pD^0$, where the signal and background contributions are considered. Our numerical results indicate that the production of $Λ_c(2880)^+$ may reach up to about 20 $μ$b. About $10^7$ events from the reconstruction of $pD^0$ can be accumulated per day, if taking the designed luminosity ($2\times10^{32}~\mbox{cm}^{-2}\mbox{s}^{-1}$) of PANDA.

hep-ph↗

arXiv2014

Probing charmonium-like state $X(3915)$ through meson photoproduction

Inspired by the observation of charmonium-like state $X(3915)$, we explore the discovery potential of the $X(3915)$ production via meson photoproduction process. By investigating the $γp \to J/ψωp$ process including the $X(3915)$ signal and background contributions, we obtain the corresponding information of the cross section, the Dalitz plot and the $J/ψω$ invariant mass spectrum, which is helpful to further experimental study of $X(3915)$ via meson photoproduction.

hep-ph↗

arXiv2013

Charged charmoniumlike state $Z_c(3900)^\pm$ via meson photoproduction

In this work, we explore the production of the newly observed charged charmoniumlike state $Z_c(3900)^\pm$ by the photoproduction process $γp\to Z_c(3900)^+n$. Our numerical result indicates that the maximum of the calculated total cross section of $γp\to Z_c(3900)^+n$ can reach up to the order of $0.1 μb$. Furthermore, the Dalitz plot analysis is performed by considering the Pomeron exchange as the background contribution. This analysis shows that the $Z_c(3900)^+$ signal can be distinguished from the background easily and the best energy window of searching for $Z_c(3900)^+$ is $\sqrt{s}\simeq7$ GeV, which is important information for further experimental study of $Z_c(3900)^+$ by meson photoproduction.

hep-ph↗

arXiv2013

A normal-pressure MWPC for beam diagnostics at RIBLL2

A normal pressure MWPC for beam diagnostics at RIBLL2 has been developed, which has a sensitive area of 80 mm$\times$80 mm and consists of three-layer wire planes. The anode plane is designed with a wider frame to reduce the discharge and without using protection wires. The detector has been tested with a $^{55}$Fe X-ray source and a 200 MeV/u $^{12}$C beam from CSRm. A position resolution better than 250 $\upmu$m along the anode wires and a detection efficiency higher than 90% have been achieved.

physics.ins-det↗

arXiv2012

Revisiting the production of charmonium plus a light meson at PANDA

In this work, we calculate the total cross sections and the center-of-mass frame angular distributions of the charmonium production plus a light meson by the low energy $p\bar{p}$ interaction. The results of $p\bar{p}\to π^0 Ψ$ with and without form factor (FF) indicate that the FF contribution in the calculation cannot be ignored. The obtained cross section of $p\bar{p}\to π^0 J/ψ$ with FF can fit the E760 data well. We also predict the total cross sections and the center-of-mass frame angular distributions of $p\bar{p}\to ωΨ$, which show that these physical quantities are dependent on Pauli ($g_ω$) and Dirac ($κ_ω$) coupling constants of the $ppω$ interaction. Thus, $p\bar{p}\to ωΨ$ can be as the ideal channel to test the different theoretical values of $g_ω$ and $κ_ω$. Applying the formulae of $p\bar{p}\to π^0 Ψ$ and $p\bar{p}\to ωΨ$, we predict the total cross sections of the $p\bar{p}\to ηΨ$ and $p\bar{p}\to ρΨ$ reactions. Our results show a common behavior of the charmonium production with a light meson by the $p\bar{p}$ interaction, where the total cross section of the $η_c$ production is the largest one among all discussed processes. The above observations can be directly tested at the forthcoming $\bar{P}$ANDA experiment.

hep-ph↗

arXiv2011

Pion productions by proton and Helium-3 on Au197 target at beam energies of 2.8, 5, 10 and 16.587 GeV/nucleon

Based on a Relativistic Boltzmann-Uehling- Uhlenbeck transport model, proton and $^{3}$He induced reactions on $^{197}$Au target at beam energies of 2.8, 5, 10 and 16.587 GeV/nucleon are studied. It is found that compared with proton induced reactions, $^{3}$He induced reactions give larger cross sections of pion production, about 5 times those of the proton induced reactions. And more importantly, pion production from $^{3}$He induced reaction is more inclined to low-angle emission. Neutrino production via positively charged pion is also discussed accordingly.

nucl-th↗

arXiv2011

Phenomenological study on the $\bar p N\to \bar NNππ$ reactions

We extend our recent phenomenological study of $pN \to NNππ$ reactions to the $\bar{p}N \to \bar{N}Nππ$ reactions for anti-proton beam momenta up to 3.0 GeV within an effective Lagrangian approach. The contribution of $N^*(1440)$ with its $Nσ$ decay mode is found to be dominant at the energies close to threshold for $\bar NNπ^+π^-$ and $\bar NNπ^0π^0$ channels. At higher energies or for $p\bar nπ^-π^-$ and $\bar NNπ^\pmπ^0$ channels where $N^*(1440)\to Nσ$ mode cannot contribute, large contributions from double-$Δ$, $Δ(1600) \to N^*(1440)π$, $Δ(1600) \to Δπ$ and $Δ(1620) \to Δπ$ are found. In the near-threshold region, sizeable contributions from $Δ\to Δπ$, $Δ\to Nπ$, $N \to Δπ$ and nucleon pole are also indicated. Although these results are similar to those for $pN\to NNππ$ reactions, the antinucleon-nucleon collisions are shown to be complementary to the nucleon-nucleon collisions and may even have advantages in some aspects. The PANDA/FAIR experiment is suggested to be an excellent place for studying the properties of relevant $N^*$ and $Δ^*$ resonances.

nucl-th↗

arXiv2010

Double pion production in $NN$ and $\bar{N}N$ collisions

With an effective Lagrangian approach, we give a full analysis on the $NN \to NNππ$ and $\bar{N}N\to \bar{N}Nππ$ reactions by exploring the roles of various resonances with mass up to 1.72 GeV. We find large contributions from $Δ$, $N^*(1440)$, $Δ(1600)$ and $Δ(1620)$ resonances. Our calculations also indicate sizeable contributions from nucleon poles for the energies close to the threshold. A good description to the existing data of different isospin channels of $NN\to NNππ$ and $\bar{N}N\to \bar{N}Nππ$ for beam energies up to 2.2 GeV is reached. Our results provide important implications to the ABC effect and guildlines to the future experimental projects at COSY, HADES and HIRFL-CSR. We point out that the PANDA at FAIR could be an essential place for studying the properties of baryon resonances and the data with baryon and anti-baryon in final states are worth analyzing.

nucl-th↗

arXiv2010

Phenomenological analysis of the double pion production in nucleon-nucleon collisions up to 2.2 GeV

With an effective Lagrangian approach, we analyze several NN \to NNππchannels by including various resonances with mass up to 1.72 GeV. For the channels with the pion pair of isospin zero, we confirm the dominance of N*(1440)\to Nσin the near threshold region. At higher energies and for channels with the final pion pair of isospin one, we find large contributions from N*(1440)\to Δπ, double-Delta, Δ(1600) \to N*(1440)π, Δ(1600) \to Δπand Δ(1620) \to Δπ. There are also sizeable contributions from Δ\to Δπ, Δ\to Nπ, N \to Δπand nucleon pole at energies close to the threshold. We well reproduce the total cross sections up to beam energies of 2.2 GeV except for the pp\to ppπ^0π^0 channel at energies around 1.1 GeV and our results agree with the existing data of differential cross sections of pp \to ppπ^+π^-, pp \to nnπ^+π^+ and pp \to ppπ^0π^0 which are measured at CELSIUS and COSY.

nucl-th↗

arXiv2009

Evidence of N*(1535) resonance contribution in the pn->dϕreaction

The N*(1535) resonance contributions to the pn->dϕreaction are evaluated in an effective Lagrangian model. The π-, η-, and ρ-meson exchange are considered. It is shown that the contributions from π- and ρ-meson exchange are dominant, while the contribution from η-meson exchange is negligibly small. Our theoretical results reproduce the experimental data of both total cross section and angular distribution well. This is another evidence that the N*(1535) resonance has large s\bar{s} component leading to a large coupling to Nϕ, which may be the real origin of the OZI rule violation in the \piN and pN reactions.

nucl-th↗

arXiv2009

Role of the N*(1440) resonance in the pp->pnpi+ reaction

New measurement by CELSIUS-WASA Collaboration on the pp->pn pi+ reaction reveals clear evidence for the presence of the Roper resonance N*(1440) which has been ignored in previous theoretical calculations. In this article, based on an effective Lagrangian approach and available knowledge on the Roper resonance, we investigate the role of the Roper resonance for the pp->pn pi+ reaction. It is found that the contribution from the Roper resonance N*(1440) becomes significant for kinetic energy above 1.1 GeV, consistent with the new experimental observation. The t-channel sigma-meson exchange is dominant for the production of the Roper resonance.

nucl-th↗

arXiv2007

Stopping effects in U+U collisions with a beam energy of 520 MeV/nucleon

A Relativistic Transport Model (ART1.0) is applied to simulate the stopping effects in tip-tip and body-body U+U collisions, at a beam kinetic energy of 520 MeV/nucleon. Our simulation results have demonstrated that both central collisions of the two extreme orientations can achieve full stopping, and also form a bulk of hot, dense nuclear matter with a sufficiently large volume and long duration, due to the largely deformed uranium nuclei. The nucleon sideward flow in the tip-tip collisions is nearly 3 times larger than that in body-body ones at normalized impact parameter $b/b_{max}<0.5$, and that the body-body central collisions have a largest negative nucleon elliptic flow $v_{2}=-12%$ in contrast to zero in tip-tip ones. Thus the extreme circumstance and the novel experimental observables in tip-tip and body-body collisions can provide a good condition and sensitive probe to study the nuclear EoS, respectively. The Cooling Storage Ring (CSR) External Target Facility (ETF) to be built at Lanzhou, China, delivering the uranium beam up to 520 MeV/nucleon is expected to make significant contribution to explore the nuclear equation of state (EoS).

nucl-ex↗