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Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a polarization of $\sim$80%) and protons (with a polarization of $\sim$70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2-3) $\times$ 10$^{33}$ cm$^{-2}$ s$^{-1}$. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC. The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies. This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China., EicC white paper, written by the whole EicC working group

The stellarator plasma device has been widely studied as one of the candidate solutions paralleling the ITER project, and its coupling with a fission blanket can bring benefits promoting the develo...

ITER is an experimental tokamak device that has many collaborators from different countries and aims to produce energy from nuclear fusion inside a reactor with magnetic confinement. Corresponding ...

The International Thermonuclear Experimental Reactor (ITER) is one of the largest international cooperative projects with many participants from different research groups in institutes and universi...

To study the burnup features of accelerator-driven subcritical systems (ADSs), simplified transmutation trajectories are imperative to make the simulation process more effective with acceptable pre...

Accurate mass data of transuranium nuclei is particularly important for the study of superheavy nuclei and the investigation of “island of stability”. A low energy mass spectrometer to provide high-precision mass measurement and isobaric separation of short-lived fusion-evaporation reaction products is planned at the Spectrometer for Heavy Atom and Nuclear Structure (SHANS). A multi-reflection time-of-flight mass analyzer for SHANS has been designed and constructed and is being tested now. In the in-trap-lift mode, the latest simulation results by using SIMION give a maximal mass resolving power of 1.6 × 105 for a TOF of 6.4 ms, and the preliminary test results by applying the simulated voltages show that its mass resolving power has reached ≈ 7000 for a TOF of 1.6 ms.

The multinucleon transfer (MNT) reaction is one promising way to produce neutron-rich heavy nuclei and even super heavy nuclei and attracts more and more attentions theoretically and experimentally. A low energy nuclear structure spectrometer called LENSHIAF specific to the MNT reactions will be designed and constructed in the ongoing big project HIAF in China. In the LENSHIAF spectrometer, the most challenge part is how to collect and stop efficiently the high-energy MNT products into the gas cell. By using Monte-Carlo method, the geometry of the gas cell, the thickness of the titanium window/degrader, and the optimal gas pressure filled in the gas cell have been calculated and estimated. For neutron-rich nuclei around N = 126 from 136Xe + 198Pt reaction, with a titanium window/degrader with a thickness of 2.5–3.5 μ m, a cylindrical helium gas cell with a length of 0.6 m and a diameter of 1.2 m can satisfy the requirements to stop the target-like fragments. For heavier and super heavy nuclei from 238U + 238U reaction, with a 5–8 μ m thick titanium window/degrader, the cylindrical gas cell has to be as big as a length of at least 1.6 m and a diameter of 1.6 m.

To study the β -delayed neutron decay of nuclei far from β stability line, a new β -delayed neutron detection system working with the continuous beam mode has been built at Peking University and tested with radioactive ion beams . To get fast timing signal for neutron Time-of-Flight (ToF) measurement and good spatial correlation between the implanted particles and the subsequent β particles, a double-sided silicon detector is sandwiched between two thin plastic scintillators , which constitute the implantation and β detection array. According to the test measurements with radioactive ion beams, this detection system has a high β coincident detection efficiency of 30 . 7 ( 5 ) % with much less disturbance from other unstable nuclei and the random background. After the time-walk correction and the flight path calibration, good energy resolution based on neutron ToF measurement can be obtained. The properties of this detection system make the study of β -delayed neutron decay of nuclei with very low beam intensity feasible.

SuperWASPJ222302.02+195031.8 is an eclipsing binary with an orbital period about 0.22517657 days that is close to the short-period limit of contact binaries. Multi-color photometric light curves of the short-period binary in B, V, Rc and Ic bands are presented and analyzed by using the Wilson–Devinney (W–D) method. It is discovered that the system is a semi-detached binary where the secondary component is already filling the critical Roche lobe, while the primary is filling just 77.1% of its Roche lobe. The temperature of the primary is about 4300 K, and the temperature difference between the two components is about 500 K. The asymmetries in the light curves are explained by the coverage of stellar dark spots on the less massive component via magnetic activity. An analysis of all available eclipse times suggests that there are no any changes in the O-C diagram. This may indicate that there are no mass transfers between the two components. The semi-detached configuration with the dark spot on the surface of the lobe-filling secondary and no variations in the orbital period make the binary an interesting target for further investigations.

A 325 MHz aluminum prototype of a spatially periodic rf quadrupole focusing linac was developed at the Institute of Modern Physics, Chinese Academy of Sciences, as a promising candidate for the front end of a high-current linac. It consists of an alternating series of crossbar H-type drift tubes and rf quadrupole sections. Owing to its special geometry, cavity fabrication is a major hurdle for its engineering development and application. In this paper, we report the detailed mechanical design of this structure and describe its fabrication process, including machining, assembly, and inspection. The field distribution was measured by the bead-pull technique. The results show that the field errors of both the accelerating and focusing fields are within an acceptable range. A tuning scheme for this new structure is proposed and verified. The cold test process and results are presented in detail. The development of this prototype provides valuable guidance for the application of the spatially periodic rf quadrupole structure., 16 pages, 7 figures, 1 table

Feasibility of subcriticality monitoring with a digital reactivity meter based on inverse kinetics method has been investigated at the lead-based zero power reactor VENUS-II. A series of control rod drop experiments have been carried out in this work. The subcriticality before and after the rod drop were estimated considering the effect of external neutron source. The control rod worth was also extracted from the rod drop experiments. The measurement results exhibited obvious spatial dependence induced by the control rod insertion, and they could be corrected by correction factors calculated with MCNP code. The corrected values of control rod worth were found to be consistent with the reference ones predetermined at critical condition. Moreover, this method could also provide real time subcriticality without any correction when the detectors were placed at appropriate positions at slightly subcritical state. Based on these measurements, it has been proved that the digital reactivity meter could be a useful tool for continuous reactivity monitoring in the operation of ADS in future.

In this article, we report a benchmark experiment of the tungsten reactivity worth under a super-critical state which has been conducted at the VENUS-II facility of CIAE in Beijing. The cylindrical tungsten target reactivity worth was measured and extracted as −1.234 ± 0.114 × 10−3 Δk/k using a period method. The resultant tungsten reactivity worth was compared with those from the MCNP Monte Carlo simulations with five evaluated libraries, i.e., ENDF/B-VII.0, ENDF/B-VII.1, CENDL-3.1, JENDL-4.0 and JEFF-3.2. It is found that the results from the MCNP simulations with ENDF/B-VII.0, ENDF/B-VII.1, JENDL-4.0 and JEFF-3.2 are overestimated, whereas that of CENDL-3.1 is underestimated, and those from the MCNP simulations with the ENDF/B-VII.1 and ENDF/B-VII.0 libraries show slight better agreement with the experiment data within errors. A correlation analysis was used to address these issues. We conclude that it is the discrepancy of the (n, γ) channel at the epithermal neutron region that mainly results in the difference between the measured and MCNP simulated tungsten reactivity worth values.

MCNPX is a general purpose Monte Carlo radiation transport code designed to track many particle types over broad ranges of energies and it has the potential to deal with Accelerator Driven System (ADS) problems. The neutronics design and analysis of ADS using MCNPX code is significantly complex mainly on constructing the three dimensional geometry model, especially when there is an additional spallation target coupled with the subcritical reactor constructed by abundant nested repeated structures in several levels. This modeling process has long been recognized as a time consuming, tedious and error-prone task, which is hard to master for novice users. Therefore, it is imperative to build a code system that can translate CAD models of ADS to the native language of MCNPX code. In this context of demand, a code system named CAD-PSMC (FreeCAD based parsing script for MCNPX code) has been developed to solve the ADS modeling conversion problems. In the framework of this code, hierarchical tree-based basic geometry classes and Boolean&Affine operations have been established with a mapping relationship to MCNPX code. Additionally, ray-casting technology and Markov chain based iteration method have been proposed to solve the problem of spline surfaces in complex geometries. Finally, the applicability and accuracy of CAD-PSMC code have been demonstrated by comparing with various reference models and numerical calculation results.

Accelerator driven system (ADS) is an advanced nuclear system with high inherent safety feature, which can transmute the nuclear waste including minor actinides (MA) and long-lived fission products (LLFPs) into short-lived fission products. In order to accomplish the neutronic simulation in ADS, a conventional way can be divided into two steps, namely the physical process of proton beam bombarding spallation target (FLUKA) and the neutron transport process in subcritical reactor coupling with a spallation neutron source (OpenMC). However, there are some difficulties in the modeling process for ADS, such as the inconsistent modeling process between FLUKA and OpenMC codes, and the error-prone process of constructing complex geometries. Therefore, it is imperative to build a code system that can convert the CAD modeling files into the input cards of Monte Carlo codes. In this context, a code system named CAD-PSFO (FreeCAD based parsing script for FLUKA and OpenMC) has been developed to solve the modeling conversion problem in ADS, in which basic geometry and boolean logic classes have been established with a mapping relationship to FLUKA and OpenMC codes, and ray-casting technology based iteration method has been proposed to solve the problem of higher-order surfaces in complex geometries. Finally, CAD-PSFO has been verified and validated by comparing with a reference model, two benchmarks, and two simulation tests.

The power optimization control strategy for China initiative Accelerator Driven subcritical System (CiADS), which focuses on the study of dynamic features and the stable operation of coupling nuclear system, is one of the most important research topics for the current engineering stage that is expected to be completed in the year 2025. However, the traditional way in handling the power control problem was carried out by specialists with transcendental knowledge and experiences, which has been believed as the high labor intensity and the brute force trial-and-error process. In this context, the Quantum Evolutionary Algorithm (QEA) has been employed to deal with the CiADS power optimization control strategy in order to fulfill the adaptive searching procedure continuously and automatically. The manipulation of proton beam intensity has been used as the main control approach, and the physical model in describing the dynamic characteristics of power control system has been constructed in coupling the lumped parameter method and the point reactor kinetics method. In addition, the logical structure of Proportional Integral Derivative (PID) controller has been established for the power control process, and the QEA has been adopted to obtain the suitable set of parameters in the PID controller. Finally, the performance of the optimization method has been verified in the predefined control scenarios, and all the numerical results show that the control method has the applicability and feasibility in solving the CiADS power control problems.

Kinetic behaviors of niobium and titanium carbide precipitates in iron are simulated with cluster dynamics. The simulations, carried out in austenite and ferrite for niobium carbides, and in austenite for titanium carbide, are analyzed for dependences on temperature, solute concentration, and initial cluster distribution. The results are presented for different temperatures and solute concentrations, compared to experimental data available. They show little impact of initial cluster distribution beyond a certain relaxation time and that highly dilute alloys with monomers only present a significantly different behavior from denser alloys or ones with different initial cluster distributions.

Accelerator driven subcritical system (ADS) is a kind of clean nuclear facility with inherent safety features. ADS facilities mainly put emphasis on studying the two following categories of isotopes, namely, the minor actinide (MA) and long-lived fission products (LLFP). However, some general burnup codes lack depletion chains for specific heavy isotopes with MA included, or treat a series of isotopes, including LLFP, as pseudo nuclides. Taking into account the above characteristics, a burnup-transport code system OMCB (OpenMC based Burnup code) has been developed based on transmutation trajectory analysis (TTA) method and Bateman equations, coupling with OpenMC code for ADS facilities. In order to make the depletion calculation process more effective and accurate, three kinds of iterations and one terminate criteria have been proposed for searching the depletion chains. Moreover, a scan mode method based high order differential expression has been proposed to remove the infinite terms in Bateman equations. Finally, a concept of sub-step predictor calculation has been introduced by combining both linear and quadratic interpolation methods, which makes cross section time-dependent in each depletion step. Four benchmarks have been used to validate OMCB code. The numerical tests demonstrate that OMCB code has a good agreement in comparison with the reference results and can be used in ADS facilities.

A new project, High Intensity heavy ion Accelerator Facility (HIAF), is currently being under design and construction in China. HIAF will provide beams of stable and unstable heavy ions with high energies, high intensities and high quality. An overview of new opportunities for atomic physics using highly charged ions and radioactive heavy ions at HIAF is given.

The DGT (Dense Granular spallation Target) is the crucial component in CiADS (China initiative Accelerator Driven subcritical System), which is the important device in connecting the high power accelerator and the subcritical reactor. In order to keep the stable and reliable running of the coupling system, the temperature control of the DGT should be carefully studied and optimized, where the gravity driven tungsten alloy granules are considered as the spallation target material and the corresponding coolant, and the working temperature in normal operation condition should be controlled around the pre-setting value without bringing the large perturbation. Two kinds of control approaches have been adopted in this research in adjusting the temperature inside the DGT, which are the intensity of proton beam and the flow speed of tungsten alloy granules. Therefore, the simulation method and the PID (Proportional Integral Derivative) controller have been established based on the cooperation of two approaches in order to better adapt to the temperature control of the DGT. Moreover, the genetic algorithm has been employed to select and optimize the key parameters in PID controller for the purpose of substituting the experiential selection in traditional manually iterative process. Finally, the temperature control system has been evaluated based on the reference control scenarios, and all the simulation results demonstrate that the optimized method has applicability and feasibility in the temperature control of the spallation target system.

We propose a class of Rate-compatible (RC) Low-density parity-check (LDPC) codes with a very wide range of code rates. To widen the range of rates, we have developed an optimal transmission scheme to push the upper bound of code rates to 0.96. Characterized by a parity check matrix in a dual-diagonal form, the proposed RC LDPC code can be encoded in linear time. Constructed from shifted identity sub-matrices, the proposed codes are particularly well-suited for the high-speed implementation of parallel encoders. Furthermore, the encoder can be implemented efficiently with several left circular shifters and XOR gates. To maximize the encoding speed, we have proposed a q-parallel encoder architecture, where q is the size of each sub-matrix. The implementation results into Field programmable gate array (FPGA) devices indicate that a 72-parallel encoder for the proposed RC LDPC code with a code rate from 0.5 to 0.96 is capable of reaching a speed of 42 Gigabits per second (Gbps) using a clock frequency of 300MHz.

The temperature control of the spallation target in accelerator driven subcritical system is the important issue that has the direct impact on stable and reliable operation of the coupling system. The China initiative accelerator driven subcritical system (CiADS) is composed by three facilities, including the high power accelerator, dense granular spallation target (DGT) and the subcritical reactor, where the DGT is the key component in connecting the accelerator and subcritical reactor, and the gravity driven tungsten alloy granules are considered as the material and coolant for the spallation target. In order to keep the working temperature in normal operation condition around the presetting value without bringing the large perturbation, the intensity of proton beam and the flow speed of tungsten alloy granules are considered as the main control approaches in adjusting the temperature inside the DGT, and the proportional integral derivative (PID) controller has been established based on the two approaches for the better adaptability to the temperature control in spallation target system. Moreover, the simulation method and quantum evolutionary algorithm have been employed for the selection and optimization of main parameters in PID controller in order to substitute the time consuming and error prone tasks in traditional experiential selection process. Finally, the reference control scenarios have been used to demonstrate the feasibility and applicability of optimized method for the temperature control of the DGT system in CiADS.

The stellarator-type Fusion-Fission Hybrid Reactor (FFHR) is an alternative conceptual design for the tokamak-based devices in order to realize the stable power output. It can bring the viable energy source for the fusion technology in a foreseeable future, and has been widely studied with a lot of advanced concepts being proposed. However, there are some challenges in the neutronics design of the FFHR blanket for the purpose of obtaining the appropriate Tritium Breeding Ratio (TBR) and blanket energy multiplication factor, since the blanket system has a complicated three-dimensional structure in helical shape, which can not be easily translated into native geometry representation syntax of most Monte Carlo neutron transport codes. In this paper, a liquid fuel, F-Li-Be molten salt, with uranium and thorium dissolved has been proposed for the preliminary design of stellarator-type FFHR blanket. Besides, the CAD-PSFO code [ 19 ] has been employed for the simulation of complex geometry structure in the helical blanket, and the OMCB package [ 22 ] has been used in the burnup analysis of the neutronics features in the molten salt blanket. Moreover, detailed geometry design of the blanket arrangement and thickness have been studied in order to meet the requirement of energy multiplication factor in the stellarator-type FFHR. Also, the composition and concentration of the fuel material and 6Li in molten salt have been discussed for the purpose of tritium self-sufficiency with steady energy supply in the whole lifetime.

The stellarator plasmas devices have some advantages in steady state operation with less magneto hydrodynamic activities, and the development of stellarator-type FFHR (Fusion-Fission Hybird Reactor) can provide viable energy in the foreseeable future with less requirements to the plasmas technology compared with the pure fusion system. However, the neutronics design of the stellarator-type FFHR has some challenges and difficulties, since the construction of helical structures with large number of high order spline surfaces are the extremely complicated process, and the physical parameters of the complex model have to be changed frequently in the primary design stage, which make the corresponding manual input simulation work into the time consuming and error prone tasks. In this context, the CAD optimization method has been used in converting the dense mesh oriented CAD structure to the low poly style, and the CAD-PSFO code has been employed for the modeling transformation process in Monte Carlo calculation. The thorium resource has been selected as the breeding material for the stellarator-type FFHR, and the polonium and natural abundance of uranium have been used as the seed fuel for the initial loading in order to get the high energy multiplication factor. The OMCB (OpenMC based Burnup code) has been introduced to study the burnup features, and stellarator-type FFHR has been designed as the multi-purposes facility that can keep tritium self-sufficiency and get the high breeding ratio with steady energy output.

The China initiative Accelerator Driven subcritical System (CiADS) has already embarked on a plan to be built in south China’s Guangdong province for the research purpose of lead–bismuth cooled fast reactor and minor-actinide transmutation technology. In comparison with the other critical reactors, it is difficult to arrange the fuel handling equipment and to make the whole core refueling plan, since there is a proton beam tube in the central of the core and the operating environment is completely opaque. In this context, an innovation design of the spallation target and fuel handling system is proposed in Institute of Modern Physics, Chinese Academy of Sciences (IMPCAS) based on an immersive Virtual Reality (VR) platform, which can fulfill the loading and refueling procedure without mutual collisions, and provide the real-time roaming experience as in the real world. Detailed information of the handling system have been introduced including the optimized logical structure in consideration of the movement of spallation target for the fuel handling process, the principle of collision detection based on the fast ray-casting technology, the real-time roaming experience with feedback control in refueling procedure, and the reliability assessment and sequential optimization for the above process. The spallation target and fuel handling system can cover all the assemblies in subcritical reactor and provide a powerful tool for the frequently updated engineering design of the CiADS project.

MCNPX is a general purpose multi-particle Monte Carlo transport code with board ranges of energies, which has already been widely employed in the fields of radiotherapy, nuclear engineering, and nuclear fusion research. The neutronics design and analysis of fusion reactor facilities using MCNPX have been considered as the time consuming and error prone tasks. For example, the ITER-type models include a lot of nested structures and complicated high-order curve surfaces, which can not be easily described in the mathematics expressions, and the spline surfaces are also not supported by the native syntax of MCNPX. In this context, a code system called CAD-PSMC (FreeCAD based parsing script for MCNPX) has been developed in IMPCAS (Institute of Modern Physics, Chinese academy of Sciences) for the study of modeling conversion problem in ITER-type neutron calculations. Two kinds of methods have been provided and discussed in the framework of this code, including the establishing of the mapping relationship between the specification tree and the build-in boolean operations in consideration of the complicated hierarchical structures, and the demonstration of fast ray-casting technology based iteration method coupling with the mesh-oriented optimized CAD geometries in solving the high-order curve surfaces related problems. Finally, the stability and feasibility of the CAD-PSMC have been verified and validated through the comparison with the selected reference models and the neutronic simulation results of the ITER-type benchmark model.

Lifetime measurements of $\ensuremath{\beta}$-decaying highly charged ions have been performed in the experimental storage ring (CSRe) by applying the isochronous Schottky mass spectrometry. The fully ionized $^{49}\mathrm{Cr}$ and $^{53}\mathrm{Fe}$ ions were produced in projectile fragmentation of $^{58}\mathrm{Ni}$ primary beam and were stored in the CSRe tuned into the isochronous ion-optical mode. The new resonant Schottky detector was applied to monitor the intensities of stored uncooled $^{49}\mathrm{Cr}^{24+}$ and $^{53}\mathrm{Fe}^{26+}$ ions. The extracted half-lives ${T}_{1/2}(^{49}\mathrm{Cr}^{24+})=44.0(27)$ min and ${T}_{1/2}(^{53}\mathrm{Fe}^{26+})=8.47(19)$ min are in excellent agreement with the literature half-life values corrected for the disabled electron capture branchings. This is an important proof-of-principle step towards realizing the simultaneous mass and lifetime measurements on exotic nuclei at the future storage ring facilities.

Isochronous mass spectrometry was applied to measure isomeric yield ratios of fragmentation reaction products. This approach is complementary to conventional gamma-ray spectroscopy in particular for measuring yield ratios for long-lived isomeric states. Isomeric yield ratios for the high-spin I = 19/2 states in the mirror nuclei 53Fe and 53Co are measured to study angular momentum population following the projectile fragmentation of 78Kr at energies of 480A MeV on a beryllium target. The 19/2 state isomeric ratios of 53Fe produced from different projectiles in the literature have also been extracted as a function of mass number difference between projectile and fragment (mass loss). The results are compared to ABRABLA07 model calculations. The isomeric ratios of 53Fe produced using different projectiles suggest that the theory underestimates not only the previously reported dependence on the spin but also the dependence on the mass loss., Comment: 6 pages, 5 figures

Accuracy of nuclear mass measurements in storage rings depends critically on the accuracy with which the revolution times of stored ions can be obtained. In such experiments, micro-channel plates (MCP) are used as timing detectors. Due to large phase space of injected secondary beams, a large number of ions cannot be stored in the ring and is lost within the first few revolutions. However, these ions interact with the detector and can saturate the MCP and thus deteriorate its performance. In order to eliminate such effects, a fast, pulsed high-voltage power supply (PHVPS) has been employed which keeps the detector switched-off during the first few revolutions. The new detector setup was taken into operation at the Experimental Cooler-Storage-Ring CSRe in Lanzhou and resulted in a significant improvement of the detector amplitude and efficiency characteristics.

In isochronous mass spectrometry (IMS) established in heavy-ion storage rings the revolution times of the stored secondary ions should be independent of their velocity spread. However, this isochronous condition is fulfilled only in first order and in a small range of revolution times. To correct for the non-isochronicity an additional measure of the velocity or magnetic rigidity of each stored ion is required. For this purpose two new time-of-flight (TOF) detectors were installed in a straight section of the experimental Cooler Storage Ring CSRe in Lanzhou. The performance of the new time-of-flight (TOF) detectors, which is crucial for the achievable efficiencies and mass resolving power, was significantly improved. The time resolution of the TOF detector in offline tests was σ = 18.5 ± 2 ps . The detector setup was put into operation with a stable beam of 78Kr.

To study the β decays of nuclei far from the β-stability line, an implantation and β detection system has been implemented at the Peking University. This detection system covers a wide energy range from keV to GeV while maintaining a good energy resolution and a low detection threshold. By correlating the implantation nuclei with their subsequent β-decays within the same pixel or adjacent pixels of a double-sided silicon detector (DSSD), the β decay properties of implanted nuclei can be measured with much less disturbance from other unstable nuclei and the random background.

Representative Elementary Volume (REV) is not only a necessary measure for studying heterogeneous pore structure of reservoir rocks but also an important parameter for core-scale numerical modeling. In this paper, we accordingly analyze the REV for different porous media with different grain sizes based on computed tomography (CT) measurement. Our results show that that CT measurement is a relible method for REV analysis and that there is an appropriate linear relationship between grain size and REV.

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., Comment: 3 pages, 2 figures

Short-lived 46 Cr, 50 Fe and 54 Ni were studied by isochronous mass spectrometry at the HIRFL-CSR facility in Lanzhou. The measured precision mass excesses ( M E ) of 46 Cr, 50 Fe and 54 Ni are − 29471 ( 11 ) keV , − 34477 ( 6 ) keV and − 39278 ( 4 ) keV , respectively. The superallowed 0 + → 0 + β -decay Q values were derived to be Q EC ( Cr 46 ) = 7604 ( 11 ) keV , Q EC ( Fe 50 ) = 8150 ( 6 ) keV and Q EC ( Ni 54 ) = 8731 ( 4 ) keV . The values for 50 Fe and 54 Ni are by one order of magnitude more precise than the adopted literature values. By combining the existing half-lives and branching ratios, we obtained the corrected F t values to be F t ( Fe 50 ) = 3103 ( 70 ) s and F t ( Ni 54 ) = 3076 ( 50 ) s . The main contribution to the F t uncertainties is now due to β -decay branching ratios, still, more high-precision measurements of the half-lives, the masses, and especially the branching ratios are needed in order to satisfy the requirements for a stringent CVC test.

Background: Fragment yields exhibit a strong odd-even staggering (OES). This OES has been experimentally observed in different fragmentation reactions with different projectile-target combinations. However, the experimental data are still scarce for fragments close to drip lines and the origin of this OES is not well understood.Purpose: More experimental data are needed to explore the origin of this OES in fragment yields and to validate fragmentation reaction models, especially for nuclei close to the drip lines. To study the pronounced OES near the proton drip line, we measured the yields of ${T}_{z}=\ensuremath{-}1$ and ${T}_{z}=\ensuremath{-}3/2$ nuclei over a wide range of mass number.Methods: The combination of a fragment separator and a storage ring at the Heavy Ion Research Facility in Lanzhou has been used to measure the yields of ${T}_{z}=\ensuremath{-}1$ and ${T}_{z}=\ensuremath{-}3/2$ fragments, produced by $^{58}\mathrm{Ni}$ projectiles impinging on a beryllium target at an energy of about 463 MeV/nucleon.Results: A very strong OES is observed in the measured yields of both ${T}_{z}=\ensuremath{-}1$ and ${T}_{z}=\ensuremath{-}3/2$ fragments. Our experimental data demonstrate that the shell structure has a significant impact on the magnitude of this OES. A comparison of different fragmentation reaction data indicates that this OES is almost independent of the projectile-target combinations and the fragmentation energy between 140 and 650 MeV/nucleon.Conclusions: Our study reveals that the OES of fragment yields originates mainly from the OES of particle-emission threshold energies, which is very close to the OES of fragment yields when the Coulomb barrier is considered in particle-emission threshold energies.

Isochronous mass spectrometry (IMS) in storage rings is a powerful tool for mass measurements of exotic nuclei with very short half-lives down to several tens of microseconds, using a multicomponent secondary beam separated in-flight without cooling. However, the inevitable momentum spread of secondary ions limits the precision of nuclear masses determined by using IMS. Therefore, the momentum measurement in addition to the revolution period of stored ions is crucial to reduce the influence of the momentum spread on the standard deviation of the revolution period, which would lead to a much improved mass resolving power of IMS. One of the proposals to upgrade IMS is that the velocity of secondary ions could be directly measured by using two time-of-flight (double TOF) detectors installed in a straight section of a storage ring. In this paper, we outline the principle of IMS with double TOF detectors and the method to correct the momentum spread of stored ions., Comment: Accepted by Nuclear Inst. and Methods in Physics Research, B

CO2sequestration in deep saline aquifers is regard as the most promising option among all the CO2storage technologies. Capillary pressure can influence the CO2storage efficiency in the aquifers. The core-scale experimental and numerical simulation studies are usually used to understand the mechanism and degree of such influence. Based on both magnetic resonance imaging (MRI) technique and numerical simulation method, this study investigates the effect of capillary pressure on the CO2displacement efficiency in water-saturated porous media especially in quantitative form. Our results indicate: (1) the magnitude of capillary pressure may significantly affect the CO2-water displacement efficiency, and the displacement efficiency declines with increasing capillary pressure; (2) Sensitivity of the numerical model to capillary pressure becomes more unobvious with increasing capillary pressure. Thus, an accurate capillary pressure parameter is particularly required for improving the reliability of the model predictions in the case of the high permeability porous media.

The experiments of two-alpha emission from Ne-17,Ne-18 excited levels were performed at the HIRFL-RIBLL facility of the Institute of Modern Physics, Lanzhou. The beams of Ne-17 at the energy of 49.9 MeV/u and Ne-18 at 51.8 MeV/u bombarded a Au-197 target to populate excited states of Ne-17,Ne-18 via Coulomb excitation. Complete kinematics measurements were achieved by the detectors of a silicon strip and CsI+PIN array. The experimental results combined with simple MC simulations show the characteristic of sequential two-alpha emission via O-14 excited states for Ne-18. The results of two-alpha emission from Ne-17 are preliminary and need further analyses.

Due to the anti-proton annihilation at Darmstadt (PANDA) experiment has rich physics studies with different event selection criteria and very high interaction rate of 2x107 /s and data rates of 200 GB/s and more, a high performance and high bandwidth data acquisition system without hardware trigger has been proposed. The data from various sub-detector systems are tagged by a very precise timestamp in front-end electronics. Event selection based on real time feature extraction, filtering and high level correlations will be executed on Advanced Telecommunications Computing Architecture (ATCA) compliant compute nodes. As a key element, the compute node that features high bandwidth connectivity and large memory for data buffering will be detailed. A demonstrator system for the electromagnetic calorimeter has been built to set up a basic system that can be interfaced to front-end electronics.

A knockout reaction induced by 6He at 61.2 MeV/u was carried out at the HIRFL-RIBLL radioactive beam line. The α core fragments at forward angles were detected in coincidence with the recoiled protons at large angles. From this coincident measurement the valence nucleon knockout mechanism and the core knockout mechanism can be separated according to the polar angle correlation between the core fragments and the recoiled protons. It is demonstrated that, when reconstructing the resonant state of a weakly bound nucleus, the contamination resulting from the core knockout mechanism should be eliminated in order to obtain the correct structure information.

Two-proton emissions from the excited states of 17,18Ne, 28P and 28,29S were investigated experimentally by the radioactive beams bombarding on the 197Au target via the Coulomb excitation. The complete-kinematics measurements were actualized by the stacks of silicon-strip detectors and CsI+PIN array detectors. The invariant mass of final systems as well as the relative momentum, opening angle, and relative energy of the two emitted protons was reconstructed under the framework of relativistic kinematics. Visible proton-proton correlations were observed in these systems. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like 2He cluster emission, three-body phase-space decay, and two-body sequential decay were taken into account. With the help of Monte-Carlo simulations, the two protons emitted from the 6.15 MeV excited state of 18Ne and the excited states in the energy region of 9.6–10.4 MeV of 29S, respectively, exhibited prominent features of 2He cluster decay while for the other cases, no obvious diproton emissions were observed.

Knockout reaction experiment was carried out by using the 6He beams at 61.2 MeV/u impinging on a CH2 target. The α core fragments at forward angles were detected in coincidence with the recoiled protons at larger angles. From this exclusive measurement the valence nucleon knockout mechanism and the core knockout mechanism can be distinguished by the relation between the polar angles of the core fragments and the recoiled protons, respectively. It is demonstrated that the core knockout mechanism may result in some strong contamination to the real invariant mass spectrum.

The proton resonant properties in 18Ne, which determine the reaction rate of the key stellar 14O(α,p)17F reaction, have been studied by using a technique of proton resonant elastic scattering of 17F+p. A 4.22 MeV/nucleon 17F radioactive ion (RI) beam was produced via a projectile-fragmentation reaction, and separated by a Radioactive Ion Beam Line in Lanzhou (RIBLL). By bombarding a thick (CH2) n target, the energy spectra of the recoiled protons were measured by two ΔE-E silicon telescopes at the center-of-mass scattering angles of θ c.m.≈175°±5°, θ c.m.≈152°±8°, respectively. Several proton resonances in 18Ne were observed clearly. A further R-matrix analysis of the experimental data is under way to determine the resonant parameters. The present work reports the preliminary results briefly.

We extend our recent phenomenological study of pN -> NN pi pi reactions to the (p) over barN -> (N) over barN pi pi reactions for anti-proton beam momenta up to 3.0 GeV within an effective Lagrangian approach. The contribution of N*(1440) with its N sigma decay mode is found to be dominant at the energies close to threshold for (N) over barN pi(+)pi(-) and (N) over barN pi(0)pi(0) channels. At higher energies or for p (n) over bar pi(-)pi(-) and (N) over barN pi(+/-)pi(0) channels where N*(1440) -> N sigma mode cannot contribute, large contributions from double-Delta, Delta(1600) -> N*(1440)pi, Delta(1600) -> Delta pi and Delta(1620) -> Delta pi are found. In the near-threshold region, sizeable contributions from Delta -> Delta pi, Delta -> N pi, N -> Delta pi and nucleon pole are also indicated. Although these results are similar to those for pN -> NN pi pi 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 Delta* resonances. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.

A prototype of time-of-flight positron emission computed tomography (TOF-PET) has been developed for acquiring the coincident detection of 511 keV γ-rays produced from positron annihilation. It consists of two 80.5 mm×80.5 mm LYSO scintillator arrays (composed of 35 ×35 pixel finger crystals) with the position sensitive photomultiplier tubes R2487 as the readout. Each array is composed of 2 mm ×2 mm×15 mm finger crystals and the average pixel pitch is 2.30 mm. The measured results indicate that the TOF information has the potential to significantly enhance the image quality by improving the noise variance in the image reconstruction. The best spatial resolution (FWHM) of the prototype for the pairs of 511 keV γ-rays is 1.98 mm and 2.16 mm in the x and y directions, respectively, which are smaller than the average pixel pitch of 2.30 mm.