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Observation of the Superheavy Nuclide 271Ds
ZHANG Zhi-Yuan, GAN Zai-Guo**, MA Long, HUANG Ming-Hui, HUANG Tian-Heng, WU Xiao-Lei, JIA Guo-Bin, LI Guang-Shun, YU Lin, REN Zhong-Zhou, ZHOU Shan-Gui, ZHANG Yu-Hu, ZHOU Xiao-Hong, XU Hu-Shan, ZHANG Huan-Qiao, XIAO Guo-Qing, ZHAN Wen-Long
Chin. Phys. Lett. 2012, 29 (1):
012502
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DOI: 10.1088/0256-307X/29/1/012502
With the recent commissioning of a gas-filled recoil separator at Institute of Modern Physics (IMP) in Lanzhou, the decay properties of 271Ds (Z=110) were studied via the 208Pb(64Ni, n) reaction at a beam energy of 313.3 MeV. Based on the separator coupled with a position sensitive silicon strip detector, we carried out the energy−position-time correlation measurements for the implanted nucleus and its subsequent decay α's. One α−decay chain for 271Ds was established. The α energy and decay time of the 271Ds nucleus were measured to be 10.644 MeV and 96.8 ms, which are consistent with the values reported in the literature.
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A Cosmic-Ray Muon Hodoscope Based on Up-down THGEM Detectors
PANG Hong-Chao, LIU Hong-Bang, **, CHEN Shi, MIN Jian, ZHENG Yang-Heng, XIE Yi-Gang, TANG Ai-Song, YANG Ya-Dan, DONG Yang, LI Min
Chin. Phys. Lett. 2012, 29 (1):
012901
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DOI: 10.1088/0256-307X/29/1/012901
Thick gas electron multipliers (THGEMs) are new types of gas detectors with merits such as a high counting rate, anti-radiation, high gain, robustness and relatively low cost. We establish an up-down THGEM detector hodoscope system for detecting and displaying muon tracks. Muon tracks can be well observed with the detectors and the present study lays an important technological foundation for the domestic and mass production of THGEMs.
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First-Principles Study of Hydrogen Impact on the Formation and Migration of Helium Interstitial Defects in hcp Titanium
LU Yong-Fang, SHI Li-Qun**, DING Wei, LONG Xing-Gui
Chin. Phys. Lett. 2012, 29 (1):
013102
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DOI: 10.1088/0256-307X/29/1/013102
We present a first-principles study of the effects of hydrogen on helium behavior in hcp titanium. The calculation indicates that the dissolved H atoms in hcp Ti change the formation energy of the interstitial He atom, but they do not change the energetically favorable occupying site of the He atom, i.e., the tetrahedral site is more favorable than the octahedral site. The impacts of H on the formation of interstitial He defects are directly related to the atomic environment around H atoms and their positions relative to interstitial He atoms as well. For He diffusion, a tetrahedral interstitial He atom can more easily migrate along the indirect tetrahedron-octahedron-tetrahedron path than the direct path of tetrahedron-tetrahedron. When a H atom exists in the first neighbor octahedral site from the He, the activation energy for He atom diffusion is 0.46 eV, which is higher than that of the He atom diffusion in perfect crystal, 0.41 eV. Increasing the number of H atoms to two, He diffusion needs much higher activation energy. This suggests that the H atoms around interstitial He may impede the migration of interstitial He atom in hcp Ti.
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Measurement of the Absolute Photoionization Cross Section for the 5P3/2 State of 87Rb in a Vapor Cell Magneto-optic Trap
HUANG Wei, RUAN Ya-Ping, JIA Feng-Dong, ZHONG Yin-Peng, LIU Long-Wei, DAI Xing-Can, XUE Ping, XU Xiang-Yuan, ZHONG Zhi-Ping**
Chin. Phys. Lett. 2012, 29 (1):
013201
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DOI: 10.1088/0256-307X/29/1/013201
We report the measurement of the absolute photoionization cross section for the 5P3/2 state of 87Rb at wavelength of 473 nm, which results in the photoelectron energies of 33 meV above the ionization threshold, using cold atoms confined in a vapor−loaded magneto-optical trap. The 87Rb 5P3/2 photoionization cross section at 473 nm is determined to be σPI=10.5±2.2 Mb. Considering the spatial distribution of the trapped atoms, the average intensity IPI of the ionization laser seen by an atom in the MOT instead of ionizing laser intensity IPI is used in our calculations for the photoionization cross sections. The excited state fraction is also accurately estimated using the latest experimental result.
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All-Optical Temporal Differentiator Using a High Resolution Optical Arbitrary Waveform Shaper
DONG Jian-Ji**, LUO Bo-Wen, ZHANG Yin, LEI Lei, HUANG De-Xiu, ZHANG Xin-Liang
Chin. Phys. Lett. 2012, 29 (1):
014203
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DOI: 10.1088/0256-307X/29/1/014203
We experimentally demonstrate an all-optical temporal differentiator using a high resolution optical arbitrary waveform shaper, which is based on liquid crystal on silicon switching elements, and both amplitude and phase of the spectrum are programmable. By designing specific transfer functions with the optical waveform shaper, we obtain first-, second-, and third-order differentiators for periodic pulses with small average errors. We also theoretically analyze the bandwidth limitation of optical waveform shaper on the differentiator.
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THz-Wave Difference Frequency Generation by Phase-Matching in GaAs/AlxGa1−xAs Asymmetric Quantum Well
CAO Xiao-Long, WANG Yu-Ye, XU De-Gang, **, ZHONG Kai, LI Jing-Hui, LI Zhong-Yang, ZHU Neng-Nian, YAO Jian-Quan,
Chin. Phys. Lett. 2012, 29 (1):
014207
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DOI: 10.1088/0256-307X/29/1/014207
An asymmetric quantum well (AQW) is designed to emit a terahertz (THz) wave by using difference frequency generation (DFG) with the structure of GaAs/Al0.2Ga0.8As/Al0.5Ga0.5As under a doubly resonant condition. It is found that the second−order nonlinear susceptibility χ(2) varies with the two pump wavelengths, and it can reach the peak value of 1.61 µm/V when the wavelengths are given as λp1=9.756 µm and λp2=10.96 µm, respectively. The numerical results show that the refractive index of one pump wave in the AQW is concerned with not only its own wavelength but also the other wavelength. Phase-matching inside the AQW can be obtained through the tuning of the two pump wavelengths.
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A 100-TW Ti:Sapphire Laser System at a Repetition Rate of 0.1 Hz
TENG Hao, MA Jing-Long, WANG Zhao-Hua, ZHENG Yi, GE Xu-Lei, ZHANG Wei, WEI Zhi-Yi**, LI Yu-Tong, ZHANG Jie,
Chin. Phys. Lett. 2012, 29 (1):
014209
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DOI: 10.1088/0256-307X/29/1/014209
We demonstrate a 100-TW-class femtosecond Ti:sapphire laser running at a repetition rate of 0.1 Hz based on a 20 TW/10 Hz laser facility (XL-II). Pumping the new stage amplifier with a 25J green Nd:glass laser, we successfully improve the laser energy to 3.4 J with duration of 29 fs, corresponding to a peak power of 117 TW.
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Polarization Beam Splitter Based on a Self-Collimation Michelson Interferometer in a Silicon Photonic Crystal
CHEN Xi-Yao**, LIN Gui-Min, LI Jun-Jun, XU Xiao-Fu, JIANG Jun-Zhen, QIANG Ze-Xuan, QIU Yi-Shen, LI Hui
Chin. Phys. Lett. 2012, 29 (1):
014210
.
DOI: 10.1088/0256-307X/29/1/014210
A polarization beam splitter based on a self-collimation Michelson interferometer (SMI) in a hole-type silicon photonic crystal is proposed and numerically demonstrated. Utilizing the polarization dependence of the transmission spectra of the SMI and polarization peak matching method, the SMI can work as a polarization beam splitter (PBS) by selecting an appropriate path length difference in the structure. Based on its novel polarization beam splitting mechanics, the polarization extinction ratios (PERs) for TM and TE modes are as high as 18.4 dB and 24.3 dB, respectively. Since its dimensions are only several operating wavelengths, the PBS may have practical applications in photonic integrated circuits.
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Shedding Phenomenon of Ventilated Partial Cavitation around an Underwater Projectile
WANG Yi-Wei, HUANG Chen-Guang, DU Te-Zhuan, WU Xian-Qian, FANG Xin, LIANG Nai-Gang, WEI Yan-Peng**
Chin. Phys. Lett. 2012, 29 (1):
014601
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DOI: 10.1088/0256-307X/29/1/014601
A new shedding phenomenon of ventilated partial cavitations is observed around an axisymmetric projectile in a horizontal launching experiment. The experiment system is established based on SHPB launching and high speed photography. A numerical simulation is carried out based on the homogeneous mixture approach, and its predicted evolutions of cavities are compared with the experimental results. The cavity breaks off by the interaction between the gas injection and the re-entry jet at the middle location of the projectile, which is obviously different from natural cavitation. The mechanism of cavity breaking and shedding is investigated, and the influences of important factors are also discussed.
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Single-Shot Measurement of Broad Bandwidth Terahertz Pulses
ZHOU Mu-Lin, LIU Feng, LI Chun, DU Fei, LI Yu-Tong**, WANG Wei-Min, SHENG Zheng-Ming, , CHEN Li-Ming, MA Jing-Long, LU Xin, DONG Quan-Li, ZHANG Jie, **
Chin. Phys. Lett. 2012, 29 (1):
015202
.
DOI: 10.1088/0256-307X/29/1/015202
We propose a new single-shot method for measuring terahertz pulses using a linearly chirped optical pulse interferogram. Modulated frequency domain phase information can be extracted by the interferogram recorded on imaging spectrographs. The terahertz pulse waveform is obtained from the phase information. We overcome the energy fluctuation problem by using the phase information, making a reference shot unnecessary and the terahertz detection more flexible and convincing.
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Hysteresis Loops and Phase Diagrams of the Spin-1 Ising Model in a Transverse Crystal Field
S. Bouhou, I. Essaoudi, A. Ainane, M. Saber, J. J. de Miguel, M. Kerouad
Chin. Phys. Lett. 2012, 29 (1):
016101
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DOI: 10.1088/0256-307X/29/1/016101
Within the framework of the effective-field theory with a probability distribution technique, which accounts for the self-spin correlation functions, the ferromagnetic spin-1 Ising model with a transverse crystal field on honeycomb, square and simple cubic lattices is studied. We have investigated the effect of the transverse crystal field on the phase diagrams, magnetization, hysteresis loops and χz,h of the system. A number of interesting phenomena of the system are discussed.
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Formation of Low-Resistant and Thermally Stable Nonalloyed Ohmic Contact to N-Face n-GaN
ZENG Chang, ZHANG Shu-Ming**, WANG Hui, LIU Jian-Ping, WANG Huai-Bing, LI Zeng-Cheng, FENG Mei-Xin, ZHAO De-Gang, LIU Zong-Shun, JIANG De-Sheng, YANG Hui
Chin. Phys. Lett. 2012, 29 (1):
017301
.
DOI: 10.1088/0256-307X/29/1/017301
We report on the formation of Ohmic contacts with low resistance and high thermal stability to N-face n-GaN for vertical structure light emitters using a Ti(50nm)/Pt(50nm)/Au(50nm) metal scheme, where the Pt layer is introduced as a blocking layer to suppress the diffusion of Au onto the N-face n-GaN surface. It is shown that unlike the conventional Ti/Al/Ti/Au contacts, the Ti/Pt/Au contacts exhibit an Ohmic behavior with a relatively low specific contact resistivity of 1.1×10−4 Ω⋅cm2 even after annealing at 350 °C. X-ray diffraction (XRD) measurements by synchrotron radiation and Auger electron spectroscopy (AES) examination are performed to understand the effects of heat treatment.
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Effect of Substrate Temperature on the Structural and Raman Properties of Ag-Doped ZnO Films
WANG Li-Na, HU Li-Zhong, ZHANG He-Qiu, **, QIU Yu, LANG Ye, LIU Guo-Qiang, QU Guang-Wei, JI Jiu-Yu, MA Jin-Xue,
Chin. Phys. Lett. 2012, 29 (1):
017302
.
DOI: 10.1088/0256-307X/29/1/017302
Ag-doped ZnO (ZnO:Ag) films are prepared on c-plane sapphire substrates by pulsed laser deposition at different substrate temperatures. The effect of substrate temperature on the ZnO:Ag film is studied in detail by EDX, XRD and Raman spectroscopy. The results reveal that raising the substrate temperature is beneficial for incorporating Ag into ZnO:Ag films in the range of our experimental temperatures and a number of Ag atoms incorporation into ZnO:Ag films may cause the (002) peak positions of the XRD spectra shift to a lower angle direction, but hardly affect the c−axis orientation of the films. The (002) peak shift ought to be due to the increase of lattice constant in the c−axis direction caused by the partial substitution of Zn2+ ions by Ag+ ions. In addition, a local vibrational mode (LVM) at 492 cm−1 induced by doping Ag occurred in the Raman spectra of all the ZnO:Ag films and its peak position hardly shifted with increasing substrate temperature. It means that the LVM can act as an indication of Ag incorporation into ZnO:Ag film.
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75As Nuclear Magnetic Resonance Studies on Ba(Fe1−xNix)2As2 Single Crystals under High Pressure
ZHANG Xiao-Dong, FAN Guo-Zhi, ZHANG Cheng-Lin, JING Xiu-Nian, LUO Jian-Lin**
Chin. Phys. Lett. 2012, 29 (1):
017401
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DOI: 10.1088/0256-307X/29/1/017401
75As nuclear magnetic resonance (NMR) was measured for Ba(Fe1−xNix)2As2 single crystals with x=0.05 and x=0.1 under 0 and 1.5 GPa, respectively. For the optimal doped sample with x=0.05, the superconducting transition temperature, Tc, is strongly suppressed from 18 to 5 K, while for the over−doped sample with x=0.1, it is turned from a superconducting ground state to a disordered paramagnetic state under 1.5 GPa. Our experimental results show that the antiferromagnetic spin fluctuations, as well as Tc, are suppressed. The experimental results can be explained with the two-band model. As a result, the electronic band is shifted downwards with an increase in pressure, and the electrons become the dominant carriers in the system.
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The Comprehensive Retrieval Method of Electromagnetic Parameters Using the Scattering Parameters of Metamaterials for Two Choices of Time-Dependent Factors
HOU Zhi-Ling**, KONG Ling-Bao, JIN Hai-Bo, CAO Mao-Sheng, LI Xiao, QI Xin
Chin. Phys. Lett. 2012, 29 (1):
017701
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DOI: 10.1088/0256-307X/29/1/017701
The electromagnetic parameters (permittivity and permeability) method, retrieved from the reflection and transmission coefficients of a slab, is presented. Improvements over existing methods, including the determination of the permittivity, permeability and impedance of the slab, are expressed as explicit functions of the S parameters for both the time−dependent factors, eiωt and e−iωt (ω is the angular frequency of the incident electromagnetic wave), and the proper selection of the sign of impedance and the real part of the refractive index. Moreover, based on the retrieving method, the calculations of the electromagnetic parameters of the conventional−material teflon slab standard sample through the experimental data of the S parameters are performed, which confirm the validity of the technique for the retrieval of electromagnetic parameters.
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The Preparation and Photoluminescence Properties of Fluorosilicate Glass Ceramics Containing CeF3:Dy3+ Nanocrystals
WU Li-Ang, FU Heng-Yi, QIAN Jiang-Yun, ZHAO Da-Liang, LUO Qun, QIAO Xu-Sheng**, FAN Xian-Ping, ZHANG Xiang-Hua
Chin. Phys. Lett. 2012, 29 (1):
017802
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DOI: 10.1088/0256-307X/29/1/017802
Ce3+ and Dy3+ co−doped oxyfluoride glasses and glass ceramics containing CeF3 nanocrystals are prepared in a reducing atmosphere. XRD measurements and the calculated lattice parameters suggest that Dy3+ ions are incorporated with precipitated CeF3 nanocrystals along with a rise in the Dy3+ concentration or an increase in the annealing temperature.
The glass ceramics emit white light close to the CIE coordinates of (0.3,0.3), derived from a combination of Ce3+ and Dy3+ emission.
The CIE chromaticity coordinates of the Ce3+ and Dy3+ co−doped glass ceramics can be tuned by varying the ratio of Ce3+/Dy3+, while the luminescence intensity can be enhanced by heat treatment above 620°C.
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Comparative Study of the Characteristics of the Basal Plane Stacking Faults of Nonpolar a−Plane and Semipolar (11
XU Sheng-Rui**, LIN Zhi-Yu, XUE Xiao-Yong, LIU Zi-Yang, MA Jun-Cai, JIANG Teng, MAO Wei, WANG Dang-Hui, ZHANG Jin-Cheng, HAO Yue
Chin. Phys. Lett. 2012, 29 (1):
017803
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DOI: 10.1088/0256-307X/29/1/017803
Nonpolar (1120) and semipolar (1122) GaN are grown on r−plane and m−plane sapphire by MOCVD to investigate the characteristics of basal plane stacking faults (BSFs). Transmission electron microscopy reveals that the density of BSFs for the semipolar (1122) and nonpolar a−plane GaN template is 3×105 cm−1 and 8×105 cm−1, respectively. The semipolar (1122) GaN shows an arrowhead−like structure, and the nonpolar a−plane GaN has a much smoother morphology with a streak along the c−axis. Both nonpolar (1120) and semipolar (1122) GaN have very strong BSF luminescence due to the optically active character of the BSFs.
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The Morphological Change of Silver Nanoparticles in Water
WANG Peng, WANG Rong-Yao**, JIN Jing-Yang, XU Le, SHI Qing-Fan**
Chin. Phys. Lett. 2012, 29 (1):
017805
.
DOI: 10.1088/0256-307X/29/1/017805
The solvent-induced morphological change of silver nanoparticles is studied with a combination of optical spectroscopy and atomic force microscopy (AFM). By using the local surface plasmon resonance (LSPR) spectroscopy arising from Ag nanoparticles, an in-situ investigation of the spectral changes is carried out before, during and after exposure of Ag island films to water. Combining with the morphological observations by AFM, we sort out the morphological and dielectric contributions to the water-induced LSPR changes. Our results demonstrate that a slight morphological change induced by water contact can result in an apparent blue shift of the LSPR spectral maximum. Furthermore, it is found that this structural change leads to a higher sensitivity of the Ag island films in response to the change in the external dielectric environment. This solvent-induced morphological change, and consequently the modification of the LSPR of the metal nanoparticles, may have significant impact in the applications of solvent-involved plasmon sensors, such as chemical/biological sensing and single-molecule spectroscopy.
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The Growth of Semi-Polar ZnO (10
SANG Ling**, WANG Jun**, SHI Kai, WEI Hong-Yuan, JIAO Chun-Mei, LIU Xiang-Lin, YANG Shao-Yan, ZHU Qin-Sheng, WANG Zhan-Guo
Chin. Phys. Lett. 2012, 29 (1):
018101
.
DOI: 10.1088/0256-307X/29/1/018101
Semi-polar ZnO (1011) epitaxial films are demonstrated using a methanol oxidant by metalorganic chemical vapor deposition on Si (111) substrates at 500°C. X−ray φ scanning indicates that there are six kinds of in−plane domain growths, with the ZnO [1012] parallel to the Si 〈112〉 direction families. The crystallographic orientation of ZnO is supposed to be caused by surface passivation. The methanol, as a polar molecule, may be adsorbed on the Si (111) surface to form a passivation layer, which inhibits the (0001) ZnO plane deposition on the substrate surface, and as a result the ZnO (1011) plane becomes preferred. The optical properties, examined by a room−temperature photoluminescence spectrum, exhibit a strong near-band-edge emission peak at 379 nm, indicating that the (1011) ZnO film has good crystal quality. These results are significant for research into and for the applications of semi-polar ZnO films.
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A Study of GaN Grown on SiH4 Pre-Treated 6H-SiC Substrates
SONG Shi-Wei, LIANG Hong-Wei**, LIU Yang, XIA Xiao-Chuan, SHEN Ren-Sheng, LUO Ying-Min, DU Guo-Tong,
Chin. Phys. Lett. 2012, 29 (1):
018102
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DOI: 10.1088/0256-307X/29/1/018102
GaN thin films are grown on Si-terminated (0001) 6H-SiC substrates pre-treated with SiH4 in a metal organic chemical vapor deposition system. The influence of the SiH4 pre−treatment conditions on the SiC surface is carefully investigated. It is found that SiH4 could react with the SiC surface oxide, which will change the surface termination. Moreover, our experiments demonstrate that SiH4 pre-treatment can distinctly influence the AlGaN nucleation layer and the basic characteristics of GaN.
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The Field Emission Characteristics of Titanium-Doped Nano-Diamonds
YANG Yan-Ning, ZHANG Zhi-Yong**, ZHANG Fu-Chun, DONG Jun-Tang, ZHAO Wu, ZHAI Chun-Xue, ZHANG Wei-Hu
Chin. Phys. Lett. 2012, 29 (1):
018103
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DOI: 10.1088/0256-307X/29/1/018103
An electrophoresis solution, prepared in a specific ratio of titanium (Ti)-doped nano-diamond, is dispersed by ultrasound and the nano-diamond coating is then deposited on a polished Ti substrate by electrophoresis. After high-temperature vacuum annealing, the appearance of the surface and the microstructures of the coating are observed by a metallomicroscope, scanning electron microscopy and Raman spectroscopy. The field emission characteristics and luminescence features are also tested, and the mechanism of the field emission characteristics of the Ti-doped nano-diamond is analyzed. The experimental results show that under the same conditions, the diamond-coated surface (by deposition) is more uniform after doping with 5 mg of Ti powder. Compared with the undoped nano-diamond cathode, the turn-on fields decline from 6.95 to 5.95 V/µm. When the electric field strength is 13.80 V/µm, the field emission current density increases to 130.00 µA/cm2. Under the applied fields, the emission current is stable and the luminescence is at its best, while the field emission characteristics of the 10 mg Ti-doped coating become worse, as does the luminescence. The reason for this could be that an excessive amount of TiC is generated on the surface of the coating.
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The Electric Mechanism of Surface Pretreatments for Dye-Sensitized Solar Cells Based on Internal Equivalent Resistance Analysis
XU Wei-Wei, HU Lin-Hua, LUO Xiang-Dong, LIU Pei-Sheng, DAI Song-Yuan**
Chin. Phys. Lett. 2012, 29 (1):
018401
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DOI: 10.1088/0256-307X/29/1/018401
Based on the optimization of dye-sensitized solar cell (DSC) photoelectrodes pretreated with different methods such as electrodeposition, spin-coating and TiCl4 pretreatment, theoretical calculations are carried out to interpret the internal electric mechanism. The numerical values, including the series resistance Rs and the shunt resistance Rsh corresponding to the equivalent circuit model, are well evaluated and confirm that the DSC has good performance with a high Rsh and a low Rs due to good electrical contact and a low charge recombination after the different modifications. The I–V curves are fitted in the case without series resistance, and account for the role of Rs in the output characteristics. It is found that when Rs tends to the infinitesimal, the short−circuit current Isc, the open−circuit voltage Voc and the fill factor can be improved by almost 0.8–1.4, 2.9 and 2.1–6.8%, respectively.
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Reactive Radiofrequency Sputtering-Deposited Nanocrystalline ZnO Thin-Film Transistors
LI Shao-Juan, HE Xin, HAN De-Dong, SUN Lei, WANG Yi, HAN Ru-Qi, CHAN Man-Sun, ZHANG Sheng-Dong, **
Chin. Phys. Lett. 2012, 29 (1):
018501
.
DOI: 10.1088/0256-307X/29/1/018501
The structural and electrical properties of ZnO films deposited by reactive radiofrequency sputtering with a metallic zinc target are systematically investigated. While the as-deposited ZnO film is in a poly-crystalline structure when the partial pressure of oxygen (pO2) is low, the grain size abruptly decreases to a few nanometers as pO2 increases to a critical value, and then becomes almost unchanged with a further increase in pO2. In addition, the resistivity of the ZnO films shows a non−monotonic dependence on pO2, including an abrupt transition of about seven orders of magnitude at the critical pO2. Thin−film transistors (TFTs) with the nanocrystalline ZnO films as channel layers have an on/off current ratio of more than 107, an off−current in the order of pA, a threshold voltage of about 4.5 V, and a carrier mobility of about 2 cm2/(V⋅s). The results show that radiofrequency sputtered ZnO with a zinc target is a promising candidate for high-performance ZnO TFTs.
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Reanalysis of the Isotopic Mixture of Neutron-Capture Elements in the Metal-Poor Star HD 175305
ZHANG Jiang, **, WANG Bo, ZHANG Bo, HAN Zhan-Wen,
Chin. Phys. Lett. 2012, 29 (1):
019701
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DOI: 10.1088/0256-307X/29/1/019701
The neutron-capture process is traditionally postulated to be responsible for the nucleosynthesis of heavy elements beyond Fe. Based on the least squares method and solar isotopic abundances from the classical model, we estimate the relative contributions of the s- and r-processes to the abundance of neutron-capture elements in the metal-poor star HD 175305 from the component coefficients. Applying the calculated component coefficients Cr and Cs, the model predicts the isotopic fractions of elements Nd, Sm and Eu to be f142+144=0.482, f152+154=0.525 and f151=0.450, respectively. As well as the observed abundances, the isotropic fractions are also consistent with the calculations. Finally, for the first time, we estimated the contribution percentage of the two neutron processes (the r− and s-processes) from the observed isotopic fractions of different elements in HD 175305, e.g. an r-process contribution of 67%-32%+21% from the 4604 Å line of Sm.
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84 articles
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