2006 Vol. 30, No. 11
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Abstract:
We study the decay widths of the narrow resonances Dsj*(2317) and Dsj(2460) in the chiral quark model, together with the well-known D* and Ds* mesons. All the parameters in our calculation are taken from Godfrey and Isgur's quark model except the π0－η mixing angle which is fixed by the Ds* decay widths. The calculated electromagnetic decay widths agree with those from other groups and the experimental data available quite well. However, the pionic decay widths of Dsj(2317) and Dsj(2460) are too small to fit the experimental data. We suspect that the simple chiral quark pion axial-vector interaction Hamiltonian is not suitable for hadron strong decays of Dsj(2317) and Dsj(2460).
We study the decay widths of the narrow resonances Dsj*(2317) and Dsj(2460) in the chiral quark model, together with the well-known D* and Ds* mesons. All the parameters in our calculation are taken from Godfrey and Isgur's quark model except the π0－η mixing angle which is fixed by the Ds* decay widths. The calculated electromagnetic decay widths agree with those from other groups and the experimental data available quite well. However, the pionic decay widths of Dsj(2317) and Dsj(2460) are too small to fit the experimental data. We suspect that the simple chiral quark pion axial-vector interaction Hamiltonian is not suitable for hadron strong decays of Dsj(2317) and Dsj(2460).
Abstract:
In this paper, the D0→π－l+νl decay process is studied by applying light-cone QCD sum rules. The form factor of D→π transition is calculated by choosing a correlation function with a chiral current to eliminate the effect caused by the uncertainty of the twist-3 function of the pion. Therefore the calculated result of the form factor is improved, and the branching ratio of the D0→π－l+νl decay process is consistent with the new experimental data.
In this paper, the D0→π－l+νl decay process is studied by applying light-cone QCD sum rules. The form factor of D→π transition is calculated by choosing a correlation function with a chiral current to eliminate the effect caused by the uncertainty of the twist-3 function of the pion. Therefore the calculated result of the form factor is improved, and the branching ratio of the D0→π－l+νl decay process is consistent with the new experimental data.
Abstract:
In the very tiny string scale, the effect of noncommutativity of space may appear. In this paper, the expression of angular momentum in Schwinger representation is briefly reviewed first, then the quantum mechanics algebra in noncommutative phase space is discussed, moreover, the angular momentum in noncommutative phase space is represented in terms of creation and annihilation operations of commutative space. At last, the angular momentum splitting effect is discussed in detail.
In the very tiny string scale, the effect of noncommutativity of space may appear. In this paper, the expression of angular momentum in Schwinger representation is briefly reviewed first, then the quantum mechanics algebra in noncommutative phase space is discussed, moreover, the angular momentum in noncommutative phase space is represented in terms of creation and annihilation operations of commutative space. At last, the angular momentum splitting effect is discussed in detail.
Abstract:
The differential cross-sections for elastic scattering of 17F and 17O on 208Pb have been measured at Radioactive Ion Beam Line at Lanzhou (RIBLL). The variation of the logarithms of differential cross-sections with the square of scattering angles shows clearly that there exists a turning point in the range of small scattering angles (6°—20°) for 17F having exotic structure, while no turning point was observed in the 17O elastic scattering. The experimental results have been compared with previous data. Systematical analysis on the available data seems to conclude that there is an exotic behavior of elastic scattering differential cross-sections of weakly bound nuclei with halo or skin structure as compared with that of the ordinary nuclei near stable line. Therefore the fact that the turning point of the logarithms of differential cross-sections appears at small angle for weakly bound nuclei could be used as a new probe to investigate the halo and skin phenomenon.
The differential cross-sections for elastic scattering of 17F and 17O on 208Pb have been measured at Radioactive Ion Beam Line at Lanzhou (RIBLL). The variation of the logarithms of differential cross-sections with the square of scattering angles shows clearly that there exists a turning point in the range of small scattering angles (6°—20°) for 17F having exotic structure, while no turning point was observed in the 17O elastic scattering. The experimental results have been compared with previous data. Systematical analysis on the available data seems to conclude that there is an exotic behavior of elastic scattering differential cross-sections of weakly bound nuclei with halo or skin structure as compared with that of the ordinary nuclei near stable line. Therefore the fact that the turning point of the logarithms of differential cross-sections appears at small angle for weakly bound nuclei could be used as a new probe to investigate the halo and skin phenomenon.
Abstract:
Based on a chiral unitary approach (ChUA), S wave Kπ scattering is studied. We consider Kπ and Kη coupled channels on isospin bases. With only one parameter, the S wave Kπ scattering phase shift data below 1.2GeV can be described,and the resultant S wave scattering lengths also coincide with the experimental values well. In this approach, a scalar resonance corresponding to the κ can be generated dynamically. Its mass and width are about 725MeV and 594MeV, respectively. A resonance corresponding to the scalar K0*(1430) can also be generated qualitatively.
Based on a chiral unitary approach (ChUA), S wave Kπ scattering is studied. We consider Kπ and Kη coupled channels on isospin bases. With only one parameter, the S wave Kπ scattering phase shift data below 1.2GeV can be described,and the resultant S wave scattering lengths also coincide with the experimental values well. In this approach, a scalar resonance corresponding to the κ can be generated dynamically. Its mass and width are about 725MeV and 594MeV, respectively. A resonance corresponding to the scalar K0*(1430) can also be generated qualitatively.
Abstract:
133Sm was produced via fusion evaporation in the reaction 40Ca+96Ru. Its β-delayed proton decay was studied by means of “p-γ” coincidence in combination with a He-jet tape transport system, including half-lives, proton energy spectra, γ-transitions following the proton emissions, and the branching ratios to the low-lying states in the grand-daughter nuclei. The possible spins and parities of 133Sm were extracted by fitting the experimental data with a statistical model calculation. The configuration-constrained nuclear potential energy surfaces of 133Sm were calculated by using the Woods-Saxon Strutinsky method. Comparing the experimental and calculated results, the spins and parities of 133Sm were assigned to be 5/2+ and 1/2－, which is reconciled with our published simple (EC+β+) decay scheme of 133Sm in 2001. In addition, our experimental data on the beta-delayed proton decay of 149Yb reported in Eur. Phys. J., 2001, A12: 1—4 was also analyzed by using the same method. The spin and parity of 149Yb was assigned to be 1/2－.
133Sm was produced via fusion evaporation in the reaction 40Ca+96Ru. Its β-delayed proton decay was studied by means of “p-γ” coincidence in combination with a He-jet tape transport system, including half-lives, proton energy spectra, γ-transitions following the proton emissions, and the branching ratios to the low-lying states in the grand-daughter nuclei. The possible spins and parities of 133Sm were extracted by fitting the experimental data with a statistical model calculation. The configuration-constrained nuclear potential energy surfaces of 133Sm were calculated by using the Woods-Saxon Strutinsky method. Comparing the experimental and calculated results, the spins and parities of 133Sm were assigned to be 5/2+ and 1/2－, which is reconciled with our published simple (EC+β+) decay scheme of 133Sm in 2001. In addition, our experimental data on the beta-delayed proton decay of 149Yb reported in Eur. Phys. J., 2001, A12: 1—4 was also analyzed by using the same method. The spin and parity of 149Yb was assigned to be 1/2－.
Abstract:
A two-dimensional Total Routhian Surface(TRS) calculation is carried out in order to ascertain if there is triaxial superdeformation in 175Hf. A five quasi-particle configuration is chosen in the calculation. Unfortunately, the TRS minimum does not show up in the total potential energy surface.
A two-dimensional Total Routhian Surface(TRS) calculation is carried out in order to ascertain if there is triaxial superdeformation in 175Hf. A five quasi-particle configuration is chosen in the calculation. Unfortunately, the TRS minimum does not show up in the total potential energy surface.
Abstract:
In the framework of the resonating group method, the binding energies of double lambda hypernuclei ^6_ΛΛHe,^5_ΛΛHe,^5_ΛΛH,^4_ΛΛHe,and ^4_ΛΛH are calculated in the chiral SU(3) quark model. In the two-cluster approximation in which a two-lambda cluster and a core nuclei are considered, one finds that the resultant binding energy of double-lambda hypernuclei ^6_ΛΛHe is in good agreement with the experimental data. It means that the chiral SU(3) quark model can well-describe the spectrum of baryon, the interactions of N-N, Y-N, and the binding energies of light lambda hpernuclei, as well as the interaction of Y-Y and the binding energy of double-lambda hypernucleus. With the same set of parameters, we calculate the binding energies of light double-lambda hypernuclei ^6_ΛΛHe,^5_ΛΛHe,^5_ΛΛH,^4_ΛΛHe,and ^4_ΛΛH and discuss the possibilities of these states.
In the framework of the resonating group method, the binding energies of double lambda hypernuclei ^6_ΛΛHe,^5_ΛΛHe,^5_ΛΛH,^4_ΛΛHe,and ^4_ΛΛH are calculated in the chiral SU(3) quark model. In the two-cluster approximation in which a two-lambda cluster and a core nuclei are considered, one finds that the resultant binding energy of double-lambda hypernuclei ^6_ΛΛHe is in good agreement with the experimental data. It means that the chiral SU(3) quark model can well-describe the spectrum of baryon, the interactions of N-N, Y-N, and the binding energies of light lambda hpernuclei, as well as the interaction of Y-Y and the binding energy of double-lambda hypernucleus. With the same set of parameters, we calculate the binding energies of light double-lambda hypernuclei ^6_ΛΛHe,^5_ΛΛHe,^5_ΛΛH,^4_ΛΛHe,and ^4_ΛΛH and discuss the possibilities of these states.
Abstract:
In the previous publications, the assignments of spin values of the superdeformed bands in A≈150 region are not consistent by different methods. In the present work, through systematical comparison and analysis of the experimental energy spectra of the superdeformed bands in this region, we obtained two formula to describe the energy spectra and moments of inertial.Using the formulas, we assigned the spins of the superdeformed bands for several nuclei in A≈150 region.
In the previous publications, the assignments of spin values of the superdeformed bands in A≈150 region are not consistent by different methods. In the present work, through systematical comparison and analysis of the experimental energy spectra of the superdeformed bands in this region, we obtained two formula to describe the energy spectra and moments of inertial.Using the formulas, we assigned the spins of the superdeformed bands for several nuclei in A≈150 region.
Abstract:
With the construction of the neutron detection wall at the external target position on Heavy Ion Research Facility in Lanzhou-Cooling Storage Ring (HIRFL-CSR), it will be possible to detect high energy neutron. A BUU model is applied to simulate the flow in both symmetric (Ni+Ni, Pb+Pb) and asymmetric(Pb+Ni) systems. It is shown that at above several hundreds MeV/u, the flow signals are very obvious and depend clearly on the centrality of the collisions. Based on the products in the forward angle less than 20°, the simulation also reveals that the determination of the reaction plane and the selection of the impact parameter, both of which are essential in the flow measurement, are well implemented. The double event and its influence on the determination of the neutron flow are also simulated.
With the construction of the neutron detection wall at the external target position on Heavy Ion Research Facility in Lanzhou-Cooling Storage Ring (HIRFL-CSR), it will be possible to detect high energy neutron. A BUU model is applied to simulate the flow in both symmetric (Ni+Ni, Pb+Pb) and asymmetric(Pb+Ni) systems. It is shown that at above several hundreds MeV/u, the flow signals are very obvious and depend clearly on the centrality of the collisions. Based on the products in the forward angle less than 20°, the simulation also reveals that the determination of the reaction plane and the selection of the impact parameter, both of which are essential in the flow measurement, are well implemented. The double event and its influence on the determination of the neutron flow are also simulated.
Abstract:
The displacement damage effects due to Non-ionizing Energy Loss (NIEL) is one reason of device-malfunction in Space. The NIEL induced by proton with energies from 10MeV to 400MeV in Si and GaAs have been calculated using updated Monte-Carlo code SHIELD.
The displacement damage effects due to Non-ionizing Energy Loss (NIEL) is one reason of device-malfunction in Space. The NIEL induced by proton with energies from 10MeV to 400MeV in Si and GaAs have been calculated using updated Monte-Carlo code SHIELD.
Abstract:
The read out system of BESⅢ-CsI(Tl) calorimeter is based on FADC. The energy corresponds to the peak of signal waveform obtained by the scanning. In order to reduce the incoherent noise counts and improve the energy resolution a rough time information can also be fetched by counting the timing step number in FADC with a precision of 50ns besides the read out of energy information. The time information and the usage of this information in beam test are presented and discussed.
The read out system of BESⅢ-CsI(Tl) calorimeter is based on FADC. The energy corresponds to the peak of signal waveform obtained by the scanning. In order to reduce the incoherent noise counts and improve the energy resolution a rough time information can also be fetched by counting the timing step number in FADC with a precision of 50ns besides the read out of energy information. The time information and the usage of this information in beam test are presented and discussed.
Abstract:
A novel backward wave oscillator based on the superradiance mechanism is designed in this paper. The superradiance mechanism in the relativistic backward oscillator was studied by the 2.5 dimensional particle simulation code KARAT. The simulation indicated that with the driving electron beam of voltage 430kV, current 4kA and pulse width 3.1ns, the device could generate sub-nanosecond microwave with peak power 1.5GW,operating frequency 10GHz, and pulse width 500ps. The peak power conversion ratio reached 87.2%. Under the superradiance mechanism, the peak power is proportional to the square of beam pulse width when the latter is less than 3.5 ns.
A novel backward wave oscillator based on the superradiance mechanism is designed in this paper. The superradiance mechanism in the relativistic backward oscillator was studied by the 2.5 dimensional particle simulation code KARAT. The simulation indicated that with the driving electron beam of voltage 430kV, current 4kA and pulse width 3.1ns, the device could generate sub-nanosecond microwave with peak power 1.5GW,operating frequency 10GHz, and pulse width 500ps. The peak power conversion ratio reached 87.2%. Under the superradiance mechanism, the peak power is proportional to the square of beam pulse width when the latter is less than 3.5 ns.
Abstract:
The BEPCⅡ project is for upgrading the Beijing Electron Positron Collider to reach a higher luminosity.BEPCⅡ is designed as micro-β plus multi-bunches with double rings and has adopted cryogenic superconducting technology. The BEPCⅡ control system is a distributed system based on EPICS. In the past few years, we went through the design stage, R&D stage, development stage and the system will be installated. The BEPCⅡ machine commissioning with beam will start in October 2006. This paper describes the BEPCⅡ~control system and the progress of its development.
The BEPCⅡ project is for upgrading the Beijing Electron Positron Collider to reach a higher luminosity.BEPCⅡ is designed as micro-β plus multi-bunches with double rings and has adopted cryogenic superconducting technology. The BEPCⅡ control system is a distributed system based on EPICS. In the past few years, we went through the design stage, R&D stage, development stage and the system will be installated. The BEPCⅡ machine commissioning with beam will start in October 2006. This paper describes the BEPCⅡ~control system and the progress of its development.
Abstract:
Firstly, this paper introduces the characteristic of accelerator survey and alignment control network and the BEPCⅡ control network in storage ring. Then presents the application and research situation of 3D control network based on Total Station and Laser Tracker in the storage ring, which is the first time application that the unified utilization of the two types instruments in such a big dimension. The emphasis is the merit and deficiency of 3D control network and the contribution of observation from Total Station. Finally, the nice application foreground of 3D control network technology is predicted.
Firstly, this paper introduces the characteristic of accelerator survey and alignment control network and the BEPCⅡ control network in storage ring. Then presents the application and research situation of 3D control network based on Total Station and Laser Tracker in the storage ring, which is the first time application that the unified utilization of the two types instruments in such a big dimension. The emphasis is the merit and deficiency of 3D control network and the contribution of observation from Total Station. Finally, the nice application foreground of 3D control network technology is predicted.
Abstract:
S-band 45MW pulse power klystron has been developed in the Institute of High Energy Physics (IHEP) for the Beijing Electron Positron Collider (BEPC) upgrade projects (BEPC-Ⅱ). This new klystron has 5 cavities in its RF-beam interaction and single RF output window, and the RF output power is 45MW at 310kV, the gain is 50dB, the efficiency 40%. The manufacturing, training and testing of a prototype klystron has been finished in IHEP and RF power 45MW at 300kV has been reached. The testing results show that all the parameters of the 45MW klystron reach the design goal.
S-band 45MW pulse power klystron has been developed in the Institute of High Energy Physics (IHEP) for the Beijing Electron Positron Collider (BEPC) upgrade projects (BEPC-Ⅱ). This new klystron has 5 cavities in its RF-beam interaction and single RF output window, and the RF output power is 45MW at 310kV, the gain is 50dB, the efficiency 40%. The manufacturing, training and testing of a prototype klystron has been finished in IHEP and RF power 45MW at 300kV has been reached. The testing results show that all the parameters of the 45MW klystron reach the design goal.
Abstract:
Using a two-dimension fully electromagnetic Particle-in-Cell(PIC) simulation, the 1.2MeV electron acce-lerator used for desulfuration and denitrogenation is studied. The results given by the simulation are credible. In addition, the effect of electron gun structure, anode structure and voltage distribution on the work performace have been investigated. With appropriate analysis, some valuable conclusion can be obtained.
Using a two-dimension fully electromagnetic Particle-in-Cell(PIC) simulation, the 1.2MeV electron acce-lerator used for desulfuration and denitrogenation is studied. The results given by the simulation are credible. In addition, the effect of electron gun structure, anode structure and voltage distribution on the work performace have been investigated. With appropriate analysis, some valuable conclusion can be obtained.
Abstract:
In-line Phase Contrast Imaging using a micro-focus X-ray source enables weakly absorbing specimens to be imaged successfully with X-rays and enhances the visibility of fine scale structure in more strongly absorbing specimens greatly. Getting the intensity on the image plane, we can get the phase contrast of an object by phase retrieval method. We got phase contrast of a black ant in different position and obtained the phase retrieval result by Transport of Intensity Equation method. On the base of edge visibility formula and entropy method, we quantitatively compare different edge visibility results of the images in different position and the differences between original phase contrast image and phase retrieval image.
In-line Phase Contrast Imaging using a micro-focus X-ray source enables weakly absorbing specimens to be imaged successfully with X-rays and enhances the visibility of fine scale structure in more strongly absorbing specimens greatly. Getting the intensity on the image plane, we can get the phase contrast of an object by phase retrieval method. We got phase contrast of a black ant in different position and obtained the phase retrieval result by Transport of Intensity Equation method. On the base of edge visibility formula and entropy method, we quantitatively compare different edge visibility results of the images in different position and the differences between original phase contrast image and phase retrieval image.
Abstract:
SHR22000 is a whole-body PET scanner developed by Hamamatsu Photonics K.K. The scanner has a 600mm patient aperture and a 225mm axial FOV, which can cover the whole human head and large portion of the body so that a common whole-body scan can be accomplished within 5 bed position with a 3.2mm average transverse resolution at 10mm from the axis of FOV. The paper gives a system performance evaluation of this scanner using GB/T 18988.1-2003/IEC 61675-1:1998 standard, which includes the spatial resolution, tomographic sensitivity, count rate characteristic, scatter fraction and recovery coefficient. At last a human body scanning result is given as an imaging example.
SHR22000 is a whole-body PET scanner developed by Hamamatsu Photonics K.K. The scanner has a 600mm patient aperture and a 225mm axial FOV, which can cover the whole human head and large portion of the body so that a common whole-body scan can be accomplished within 5 bed position with a 3.2mm average transverse resolution at 10mm from the axis of FOV. The paper gives a system performance evaluation of this scanner using GB/T 18988.1-2003/IEC 61675-1:1998 standard, which includes the spatial resolution, tomographic sensitivity, count rate characteristic, scatter fraction and recovery coefficient. At last a human body scanning result is given as an imaging example.
Abstract:
LLNL bring forward an arithmetic of the plutonium age with the 330---350keV(Pu300) energy window. And another arithmetic of plutonium age with the same energy window is proposed in this paper. The ages of two plutonium samples were calculated with this arithmetic, and the comparison with the results from PC/FRAM indicates that the proposed arithmetic is rather reasonable.
LLNL bring forward an arithmetic of the plutonium age with the 330---350keV(Pu300) energy window. And another arithmetic of plutonium age with the same energy window is proposed in this paper. The ages of two plutonium samples were calculated with this arithmetic, and the comparison with the results from PC/FRAM indicates that the proposed arithmetic is rather reasonable.
Abstract:
The pairwise entanglement of the Heisenberg XX chain with next-nearest-neighbor (NNN) interactions was investigated by using the concurrence measure. The results show that for the nearest-neighbor sites, the entanglement may be improved or suppressed depending on the magnitudes of the NNN coupling constant J, while for the next-nearest-neighbor sites, it always increases with the increase of |J|. The critical temperature Tc decreases with the increase of J for the nearest-neighbor entanglement and increases with the increase of |J| for the next-nearest-neighbor entanglement, respectively. We also show that the general Heisenberg XX model still can be used to create the entangled W states of three and four qubits, and that the presence of NNN coupling has no effect on the creation of four-qubit W states, while it shifts the instant of time at which the three-qubit W states are created.
The pairwise entanglement of the Heisenberg XX chain with next-nearest-neighbor (NNN) interactions was investigated by using the concurrence measure. The results show that for the nearest-neighbor sites, the entanglement may be improved or suppressed depending on the magnitudes of the NNN coupling constant J, while for the next-nearest-neighbor sites, it always increases with the increase of |J|. The critical temperature Tc decreases with the increase of J for the nearest-neighbor entanglement and increases with the increase of |J| for the next-nearest-neighbor entanglement, respectively. We also show that the general Heisenberg XX model still can be used to create the entangled W states of three and four qubits, and that the presence of NNN coupling has no effect on the creation of four-qubit W states, while it shifts the instant of time at which the three-qubit W states are created.
Abstract:
We construct a three dimensional two-level hydrogen model in intense laser fields, and solve the time-dependent Schr\"{o}dinger equation non-perturbatively and numerically. The high-order harmonic generation spectrum is obtained.
We construct a three dimensional two-level hydrogen model in intense laser fields, and solve the time-dependent Schr\"{o}dinger equation non-perturbatively and numerically. The high-order harmonic generation spectrum is obtained.
Abstract:
We present a review of the recent work related to interpreting the exotic particle X(1835) reported by BES as a NN-baryonium in the Skyrme model. There are two evidences that support this interpretation:1) There exists a classical NN-Skyrmion solution with about ～10MeV binding energy in the model; 2) The decay of this Skymion-baryonium is caused by annihilation of p-p inside X(1835) through the quantum tunneling effect, and hence the most favorable decay channels are X→η4π or X→η' 2π. These lead to reasonable interpreting the data of BES, and especially to useful prediction on the decay mode of X(1835) for the experiment.
We present a review of the recent work related to interpreting the exotic particle X(1835) reported by BES as a NN-baryonium in the Skyrme model. There are two evidences that support this interpretation:1) There exists a classical NN-Skyrmion solution with about ～10MeV binding energy in the model; 2) The decay of this Skymion-baryonium is caused by annihilation of p-p inside X(1835) through the quantum tunneling effect, and hence the most favorable decay channels are X→η4π or X→η' 2π. These lead to reasonable interpreting the data of BES, and especially to useful prediction on the decay mode of X(1835) for the experiment.
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