Showing papers in "Chinese Physics C in 2012"
TL;DR: Ame2012 as discussed by the authors is the second part of the new evaluation of atomic masses, Ame2012. From the results of a least-squares calculation, described in Part I, for all accepted experimental data, derive here tables and graphs to replace those of Ame2003.
Abstract: This paper is the second part of the new evaluation of atomic masses, Ame2012. From the results of a least-squares calculation, described in Part I, for all accepted experimental data, we derive here tables and graphs to replace those of Ame2003. The first table lists atomic masses. It is followed by a table of the influences of data on primary nuclides, a table of separation energies and reaction energies, and finally, a series of graphs of separation and decay energies. The last section in this paper lists all references to the input data used in Part I of this Ame2012 and also to the data included in the Nubase2012 evaluation (first paper in this issue).
1,432 citations
TL;DR: The Nubase2012 evaluation as mentioned in this paper contains the recommended values for nuclear and decay properties of nuclides in their ground and excited isomeric (T1/2≥100 ns) states.
Abstract: This paper presents the Nubase2012 evaluation that contains the recommended values for nuclear and decay properties of nuclides in their ground and excited isomeric (T1/2≥100 ns) states. All nuclides for which some experimental information is known are considered. Nubase2012 covers all up to date experimental data published in primary (journal articles) and secondary (mainly laboratory reports and conference proceedings) references, together with the corresponding bibliographical information. During the development of Nubase2012, the data available in the "Evaluated Nuclear Structure Data File" (Ensdf) database were consulted, and critically assessed of their validity and completeness. Furthermore, a large amount of new and somewhat older experimental results that were missing in Ensdf were compiled, evaluated and included in Nubase2012. The atomic mass values were taken from the "Atomic Mass Evaluation" (Ame2012, second and third parts of the present issue). In cases where no experimental data were available for a particular nuclide, trends in the behavior of specific properties in neighboring nuclei (TNN) were examined. This approach allowed to estimate, whenever possible, values for a range of properties, and are labeled in Nubase2012 as "non-experimental" (flagged "#"). Evaluation procedures and policies that were used during the development of this database are presented, together with a detailed table of recommended values and their uncertainties.
330 citations
TL;DR: In this article, the authors studied the possible existence of very loosely bound hidden-charm molecular baryons composed of an anti-charmed meson and a charmed baryon.
Abstract: Using the one-boson-exchange model, we studied the possible existence of very loosely bound hidden-charm molecular baryons composed of an anti-charmed meson and a charmed baryon. Our numerical results indicate that the Σc* and Σc states exist, but that the Λc and Λc* molecular states do not.
206 citations
TL;DR: In this article, the lepton flavor mixing matrix U consists of a constant leading term U-0 and a small perturbation term Delta U, and the mixing angles of U are associated with lepton mass ratios.
Abstract: The Daya Bay collaboration has recently reported its first (nu) over bar (e) -> (nu) over bar (e) oscillation result which points to theta(13) similar or equal to 8.8 degrees +/- 0.8 degrees (best-fit +/-1 sigma range) or theta(13) not equal 0 degrees at the 5.2 sigma level. The fact that this smallest neutrino mixing angle is not strongly suppressed motivates us to look into the underlying structure of lepton flavor mixing and CP violation. Two phenomenological strategies are outlined: (1) the lepton flavor mixing matrix U consists of a constant leading term U-0 and a small perturbation term Delta U; and (2) the mixing angles of U are associated with the lepton mass ratios. Some typical patterns of U-0 are reexamined by constraining their respective perturbations with current experimental data. We illustrate a few possible ways to minimally correct U-0 in order to fit the observed values of three mixing angles. We point out that the structure of U may exhibit an approximate mu-tau permutation symmetry in modulus, and reiterate the geometrical description of CP violation in terms of the leptonic unitarity triangles. The salient features of nine distinct parametizations of U are summarized, and its Wolfenstein-like expansion is presented by taking U-0 to be the democratic maxing pattern.
45 citations
TL;DR: The number of J/psi events collected with the BESIII detector at the BEPC II from June 12 to July 28, 2009 is determined to be (225.3 +/- 2.8) x 10(6) using J/PSI -> inclusive events, where the uncertainty is the systematic error and the statistical one is negligible as discussed by the authors.
Abstract: The number of J/psi events collected with the BESIII detector at the BEPC II from June 12 to July 28, 2009 is determined to be (225.3 +/- 2.8) x 10(6) using J/psi -> inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.
45 citations
TL;DR: The T2K Collaboration has recently reported a remarkable indication of the nu(mu) -> nu(e) oscillation which is consistent with a relatively large value of theta(13) in the three-flavor neutrino mixing scheme as discussed by the authors.
Abstract: The T2K Collaboration has recently reported a remarkable indication of the nu(mu) -> nu(e) oscillation which is consistent with a relatively large value of theta(13) in the three-flavor neutrino mixing scheme. We show that it is possible to account for such a result of theta(13) by introducing a natural perturbation to the democratic neutrino mixing pattern, without or with CP violation. A testable correlation between theta(13) and theta(23) is predicted in this ansatz. We also discuss the Wolfenstein-like parametrization of neutrino mixing, and comment on other possibilities of generating sufficiently large theta(13) at the electroweak scale.
43 citations
TL;DR: In this article, the authors performed an extensive study of the possible B*, B**, D*, D** molecular states with various quantum numbers after considering the S-wave and D-wave mixing.
Abstract: In the framework of the one-boson-exchange model, we have performed an extensive study of the possible B*, B**, D*, D** molecular states with various quantum numbers after considering the S-wave and D-wave mixing. We also discuss the possible experimental research of these interesting states.
42 citations
TL;DR: In this paper, a high dynamic range readout system, consisting of a multi-dynode readout PMT and a VA32 chip, is presented, and an LED system is set up to calibrate the relative gains between the dynodes, and the ADC counts per MIPs from dynode 7 are determined under cosmic-ray calibration.
Abstract: A high dynamic range readout system, consisting of a multi-dynode readout PMT and a VA32 chip, is presented. An LED system is set up to calibrate the relative gains between the dynodes, and the ADC counts per MIPs from dynode 7 are determined under cosmic-ray calibration. A dynamic range from 0.5 MIPs to 1 x 10(5) MIPs is achieved.
36 citations
TL;DR: In this article, the single photoelectron charge response, waveform shape, nonlinearity, saturation, overshoot, oscillation, prepulsing, and afterpulsing were used to build a detailed model of the PMT signal characteristics.
Abstract: Detailed measurements of Hamamatsu R5912 photomultiplier signals are presented, including the single photoelectron charge response, waveform shape, nonlinearity, saturation, overshoot, oscillation, prepulsing, and afterpulsing. The results were used to build a detailed model of the PMT signal characteristics over a wide range of light intensities. Including the PMT model in simulated Daya Bay particle interactions shows no significant systematic effects that are detrimental to the experimental sensitivity.
34 citations
TL;DR: In this paper, a non-equilibrium generation of long half-life isotopes during the running time of the Daya Bay Reactor antineutrino experiment was analyzed.
Abstract: The Daya Bay Reactor Antineutrino Experiment is designed to determine the as yet unknown neutrino mixing angle, θ13, by measuring the disappearance of electron antineutrinos from several nuclear reactor cores. The projected sensitivity in sin2 (2θ13) of better than 0.01 at a 90% CL should be achieved after three years of data-taking. Antineutrinos emitted from spent nuclear fuel (SNF) distort the soft part of the energy spectrum. In this article, a calculation of the antineutrino spectra from the long-life isotopes in SNF is performed. A non-equilibrium generation of long half-life isotopes during the running time of the reactor is also analyzed. Finally, we show that the antineutrino event rate contribution from SNF, which has been stored in the SNF pool for several years, may be non-negligible.
23 citations
TL;DR: In this paper, a multi-gap resistive plate chamber (MRPC) with a 2×6 gap structure is developed for the upgrading of the endcap time-of-flight (ETOF) detector in the Beijing Spectrometer (BESIII).
Abstract: A prototype multi-gap resistive plate chamber (MRPC) with a 2×6 gap structure is developed for the upgrading of the endcap time-of-flight (ETOF) detector in the Beijing Spectrometer (BESIII). The prototype MRPC is tested in the E3 beam line of the Beijing Electron Positron Collider (BEPC) with secondary charged particles (π and p, etc) of 600 MeV/c. The test results show that the time resolution of the MRPC can reach 50 ps and that the detection efficiency is greater than 98%.
TL;DR: In order to transmit secure messages, a quantum secure direct communication protocol based on a five-particle cluster state and classical XOR operation is presented and analysis results indicate that the protocol is more secure than the other two.
Abstract: In order to transmit secure messages, a quantum secure direct communication protocol based on a five-particle cluster state and classical XOR operation is presented. The five-particle cluster state is used to detect eavesdroppers, and the classical XOR operation serving as a one-time-pad is used to ensure the security of the protocol. In the security analysis, the entropy theory method is introduced, and three detection strategies are compared quantitatively by using the constraint between the information that the eavesdroppers can obtain and the interference introduced. If the eavesdroppers intend to obtain all the information, the detection rate of the original ping-pong protocol is 50%; the second protocol, using two particles of the Einstein-Podolsky-Rosen pair as detection particles, is also 50%; while the presented protocol is 89%. Finally, the security of the proposed protocol is discussed, and the analysis results indicate that the protocol in this paper is more secure than the other two.
TL;DR: In this paper, the authors derived constraints on the related couplings in family non-universal Z' models and showed that the forward-backward asymmetry in B → K*l+l− decay can be explained by flipping the signs of the Wilson coefficients C9eff and C10.
Abstract: In a combined investigation of B → K(*)l+l− decays, constraints on the related couplings in family non-universal Z' models are derived. We find that within the allowed parameter space, the recently observed forward-backward asymmetry in the B → K*l+l− decay can be explained by flipping the signs of the Wilson coefficients C9eff and C10. With the obtained constraints, we also calculate the branching ratio of the Bs → μ+μ− decay. The upper bound of our prediction is nearly an order of magnitude smaller than the upper bound given by the CDF Collaboration recently.
TL;DR: In this article, the design and beam simulation of the superconducting section of the injector II, the acceptance calculation and a stability analysis are presented for the accelerator-driven system (ADS) project.
Abstract: The high-current superconducting proton linac is being studied for the accelerator-driven system (ADS) project undertaken by the Chinese Academy of Sciences. The injector II will be operated at 162.5 MHz, and the proton out from the RFQ with an energy of 2.5 MeV will be accelerated to 10 MeV by two cryo-modules, which are composed of eight superconducting half wave resonance cavities and nine solenoids. In this paper, the design and beam simulation of the superconducting section of the injector II, the acceptance calculation and a stability analysis are presented.
TL;DR: In this article, the feasibility of using frequency gradient analysis (FGA) to discriminate neutrons and γ rays in the environment of an 8-bit sampling system has been investigated.
Abstract: The feasibility of using frequency gradient analysis (FGA), a digital method based on Fourier transform, to discriminate neutrons and γ rays in the environment of an 8-bit sampling system has been investigated. The performances of most pulse shape discrimination methods in a scintillation detection system using the time-domain features of the photomultiplier tube anode signal will be lower or non-effective in this low resolution sampling system. However, the FGA method using the frequency-domain features of the anode signal exhibits a strong insensitivity to noise and can be used to discriminate neutrons and γ rays in the above sampling system. A detailed study of the quality of the FGA method in BC501A liquid scintillators is presented using a 5 G samples/s 8-bit oscilloscope and a 14.1 MeV neutron generator. A comparison of the discrimination results of the time-of-flight and conventional charge comparison (CC) methods proves the applicability of this technique. Moreover, FGA has the potential to be implemented in current embedded electronics systems to provide real-time discrimination in standalone instruments.
TL;DR: In this article, a modified version of quark mass scaling via considering the important one-gluonexchange interaction between quarks in the quark density-dependent model is presented.
Abstract: We present a modified version of quark mass scaling via considering the important one-gluonexchange interaction between quarks in the quark mass density-dependent model. The properties of strange quark matter and the structure of strange stars are then studied with the new scaling and a self-consist...
TL;DR: In this article, a compact multiplexed readout based on a discretized positioning circuit (DPC) was developed to reduce the readout channels from 16 to 4 outputs.
Abstract: This work aims at developing compact readout electronics for a compact imaging detector module with silicon photomultiplier (SPM) array. The detector module consists of a LYSO crystal array coupling with a SensL's 4×4 SPM array. A compact multiplexed readout based on a discretized positioning circuit (DPC) was developed to reduce the readout channels from 16 to 4 outputs. Different LYSO crystal arrays of 4×4, 8×8 and 12×12 with pixel sizes of 3.2, 1.6 and 1.0 mm respectively, have been tested with the compact readout board using a 137Cs source. The initial results show that the compact imaging detector module with the compact multiplexed readout could clearly resolve 1 mm×1 mm×10 mm LYSO scintillation crystal array except those at the edges. The detector's intrinsic spatial resolution up to 1 mm can be achieved with the 3 mm×3 mm size SPMArray4 through light sharing and compact multiplexed readout. Our results indicate that this detector module is feasible for the development of high-resolution compact PET.
TL;DR: In this article, the covariant density functional theory was applied to the α-cluster structures for 12C and 16O in the framework of the covariance functional theory, where the pairing correlation was treated with a particle number conserving shell-model-like approach.
Abstract: The α-cluster structures for 12C and 16O are investigated in the framework of the covariant density functional theory, where the pairing correlation is treated with a particle number conserving shell-model-like approach. The ground states of 12C and 16O have been calculated and the density distributions demonstrate an equilateral triangle 3α clustering for 12C and a regular tetrahedron 4α clustering for 16O. The existence of linear nα chain structure of both 12C and 16O is revealed at high quadrupole deformation.
TL;DR: In this article, the authors used a nested minimization procedure to optimize the data taking plan and found that by using five energy points with the total integrated luminosity of 100 pb−1, the τ mass can be determined with a statistical error of 50 keV.
Abstract: Scenarios for the τ mass measurement at the upgraded Beijing Electron-Positron Collider (BEPC-II) are studied. A nested minimization procedure is used to optimize the data taking plan. It is found that by using five energy points with the total integrated luminosity of 100 pb−1,the τ mass can be determined with a statistical error of 50 keV.
TL;DR: Recently, the LHCb experiment announced 3.5σ evidence for direct CP violation in D0 decay by looking at the difference between ACP(D0 → K+K−) and ACP (D0→ π+π−) as mentioned in this paper, which may indicate new physics beyond the Standard Model.
Abstract: Recently, the LHCb experiment announced 3.5σ evidence for direct CP violation in D0 decay by looking at the difference between ACP(D0 → K+K−) and ACP(D0 → π+π−). This is the first evidence of CP violation in a charm system, which may indicate new physics beyond the Standard Model. Motivated by this measurement, we review rare processes in charmonium decay, especially, the weak decay, C or P violated decay, and lepton flavor violated decays. In case the new physics appears in charm sector, these rare decays of charmonium states will provide an opportunity to search for significant contributions from physics beyond the Standard Model. With huge J/ψ and ψ (2S) samples in BESIII experiment, the rare decays may be feasible.
Peking University1, University of Science and Technology of China2, Zhejiang University3, Zhengzhou University4, Tsinghua University5, Guangxi University6, University of Hawaii7, Johns Hopkins University8, Shandong University9, University of the Punjab10, Nankai University11, Sichuan University12, Central China Normal University13, Wuhan University14, Chinese Academy of Sciences15, Henan Normal University16, Nanjing Normal University17, Liaoning University18, Seoul National University19, Nagoya University20, Guangxi Normal University21, Soochow University (Suzhou)22, China Center of Advanced Science and Technology23, Hunan University24
TL;DR: Based on 58 million J/psi events collected by the BES II detector at the BEPC, the first time JPsi-> Lambda(Lambda) over bar pi(+)pi(-) is observed for the first.
Abstract: Based on 58 million J/psi events collected by the BES II detector at the BEPC, J/psi -> Lambda(Lambda) over bar pi(+)pi(-) is observed for the first time. The branching fraction is measured to be Br(J/psi -> Lambda(Lambda) over bar pi(+)pi(-)) = (4.30 +/- 0.13 +/- 0.99)x10(-3), excluding the decays to intermediate states, namely J/psi -> Xi(-)(Xi) over bar (+), J/psi -> Sigma(1385)(-)(Sigma) over bar (1385)(+), and J/psi -> Sigma(1385)(+)(Sigma) over bar (1385)(-). The branching fractions for these intermediate resonance channels are measured to be: Br(J/psi -> Xi(-)(Xi) over bar (+)) = (0.90 +/- 0.03 +/- 0.18) x 10(-3), Br(J/psi -> Sigma(1385)(-)(Sigma) over bar (1385)(+)) = (1.23 +/- 0.07 +/- 0.30) x 10(-3), and Br(J/psi -> Sigma(1385)(+)(Sigma) over bar (1385)(-)) = (1.50 +/- 0.08 +/- 0.38) x 10(-3), respectively. The angular distribution is of the form dN/d(cos theta) proportional to (1+ alpha cos(2)theta) with alpha = (0.35 +/- 0.29 +/- 0.06) for J/psi -> Xi(-)(Xi) over bar (+), alpha = (-0.54 +/- 0.22 +/- 0.10) for J/psi -> Sigma(1385)(-)(Sigma) over bar (1385)(+), and alpha = (-0.35 +/- 0.25 +/- 0.06) for J/psi -> Sigma(1385)(+)(Sigma) over bar (1385)(-).
TL;DR: In this article, the mass spectra of the ground states of the scalar and axial-vector diquarks, which are composed of two-light, one-light-one-heavy and two-heavy (H-H) quarks, respectively, have been calculated in terms of the QCD sum rules.
Abstract: Since the birth of the quark model, the diquark, which is composed of two quarks, has been considered as a substantial structure of a color anti-triplet. This is not only a mathematical simplification for dealing with baryons, but also provides a physical picture where the diquark would behave as a whole object. It is natural to ask whether such a structure is sufficiently stable against external disturbance. The mass spectra of the ground states of the scalar and axial-vector diquarks, which are composed of two-light (L-L), one-light-one-heavy (H-L) and two-heavy (H-H) quarks, respectively, have been calculated in terms of the QCD sum rules. We suggest a criterion as the quantitative standard for the stability of the diquark. It is the gap between the masses of the diquark and √s0 where s0 is the threshold of the excited states and continuity, namely the larger the gap is, the more stable the diquark would be. In this work, we calculate the masses of the H-H type to complete the series of the spectra of the ground state diquarks. However, as the criterion being taken, we find that all the gaps for the various diquarks are within a small range. In particular, the gap for the diquark with two heavy quarks, which is believed to be a stable structure, is slightly smaller than that of the other two types of diquarks. Therefore we conclude that because of the large theoretical uncertainty, we cannot use the numerical results obtained with the QCD sum rules to assess the stability of diquarks, but need to invoke other theoretical framework.
TL;DR: In this paper, a new structure of 3βλ/2 spoke cavity is first studied in detail, and its RF and mechanical properties are simulated using CST-MWS and ANSYS, and compared with the traditional βλ 2 spoke structure.
Abstract: Very low Beta superconducting spoke cavity is one of the key challenges for the China-ADS project. In this paper, a new structure of 3βλ/2 spoke cavity is first studied in detail. Its RF and mechanical properties are simulated using CST-MWS and ANSYS, and compared with the traditional βλ/2 spoke structure.
TL;DR: In this article, a best-fit to the Type Ia supernovae (SNe) observations yields that the Omega(Lambda) in the Lambda-CDM model is suppressed to almost zero.
Abstract: Gravitational field equations in Randers-Finsler space of approximate Berwald type are investigated. A modified Friedmann equation and a new luminosity distance-redshift relation is proposed. A best-fit to the Type Ia supernovae (SNe) observations yields that the Omega(Lambda) in the Lambda-CDM model is suppressed to almost zero. This fact indicates that the astronomical observations on the Type Ia SNe can be described well without invoking any form of dark energy. The best-fit age of the universe is given. It is in agreement with the age of our galaxy.
TL;DR: In this paper, the authors describe the characteristic features of the ringing following large PMT signals in the Daya Bay reactor antineutrino experiment and conclude that the ceramic capacitors used in the circuitry of the PMT bases and the HV-signal decouplers are the primary cause for this ringing.
Abstract: We describe here the characteristic features of the ringing we observed following large PMT signals in the Daya Bay reactor antineutrino experiment. We conclude that the ceramic capacitors used in the circuitry of the PMT bases and the HV-signal decouplers are the primary cause for this ringing. We present some possible schemes to reduce the ringing when replacing these ceramic capacitors is not feasible.
TL;DR: In this article, the gas gain and energy resolution of single and double THGEM detectors (5 cm × 5 cm effective area) with mini-rims (rim less than 10 μ m) were studied.
Abstract: The gas gain and energy resolution of single and double THGEM detectors (5 cm × 5 cm effective area) with mini-rims (rim less than 10 μ m) were studied. The maximum gain was found to reach 5 × 103 and 2 × 105 for single and double THGEMs respectively, while the energy resolution for 5.9 keV X-rays varied from 18% to 28% for both single and double THGEM detectors of different hole sizes and thicknesses. Different combinations were also investigated of noble gases (argon, neon) mixed with a quantity of other gases (isobutane, methane) at atmospheric pressure.
TL;DR: In this paper, a photon conversion finder based on track information from the main drift chamber (MDC) of the Beijing Spectrometer (BESIII) at the Beijing Electron Positron Collider (BEPCII) is developed.
Abstract: A photon conversion finder (PCF) based on track information from the main drift chamber (MDC) of the Beijing Spectrometer (BESIII) at the Beijing Electron Positron Collider (BEPCII) is developed. The validation of the PCF is done by reconstructing π0 and measuring the branching fraction of J/ψ → γη'. Using the developed PCF tool, we mapped the materials from the interaction point through the BEPCII beam pipe up to the inner wall of the MDC.
TL;DR: In this paper, a readout system for X-ray CCDs based on an improved architecture is presented; by optimizing several critical circuit blocks along the analog signal chain, the conflict between the readout speed and readout noise is greatly alleviated.
Abstract: A readout system for X-ray CCDs based on an improved architecture is presented; by optimizing several critical circuit blocks along the analog signal chain, the conflict between the readout speed and readout noise is greatly alleviated. Using CCD47-10 as its target CCD, the readout system has achieved 8.6e− readout noise and 142 eV FWHM at 5.9 keV Mn Kα under a pixel rate of 80 kHz. Also its performance of imaging has been investigated.
TL;DR: In this paper, a thermal neutron detector was developed to fulfill the requirements of the high intensity power diffractometer (HIPD) at the Chinese Spallation Neutron Source (CSNS).
Abstract: The investigation of a novel thermal neutron detector is developed to fulfill the requirements of the high intensity power diffractometer(HIPD) at the Chinese Spallation Neutron Source(CSNS).It consists of two layers of 6LiF/ZnS(Ag) scintillators,two layers of crossed WLSF arrays,several multi-anode...
TL;DR: A new scanning geometry is set up for CL, and the algebraic reconstruction technique (ART) for CL imaging is studied, which proves that ART algorithm is a good choice for the CL system.
Abstract: Computed laminography (CL) is an alternative to computed tomography if large objects are to be inspected with high resolution. This is especially true for planar objects. In this paper, we set up a new scanning geometry for CL, and study the algebraic reconstruction technique (ART) for CL imaging. We compare the results of ART with variant weighted functions by computer simulation with a digital phantom. It proves that ART algorithm is a good choice for the CL system.