2-7 Voltage Calibration and Energy Spread Measurement of 320 kV Platform at the Institute of Modern Physics

Four key reactions, 12C(, )13O, 13C(, n)16O, 25Mg(p, )26Al and 19F(p, )16O, will be studied for the first time within or near the astrophysical relevant energy regions (Gamow window) at Jinping Underground laboratory for Nuclear Astrophysics (JUNA)[1], which will take the advantage of the ultra-low background of China JinPing underground Laboratory (CJPL), high current accelerator based on ECR source and a highly sensitive detection system.

Application of FLUKA and OpenMC in coupled physics calculation of target and subcritical reactor for ADS

The study of accelerator-driven subcritical reactor systems(ADSs) has been an important research topic in the field of nuclear energy for years. The main code applied in ADS research is MCNPX, which was developed by Los Alamos National Laboratory. We studied the application of the open-source Monte Carlo codes FLUKA and OpenMC to a coupled ADS calculation. The FLUKA code was used to simulate the reaction of highenergy protons with the nucleus of the target material in the ADS, which produces spallation neutrons. Information on the spallation neutrons, such as their energy, position,direction, and weight, can be recorded by a user-defined routine called FLUSCW provided by FLUKA. Then, the information was stored in an external neutron source file in HDF5 format by using a conversion code, as required by the OpenMC calculation. Finally, the fixed-source calculation function of OpenMC was applied to simulate the transport of spallation neutrons and obtain the distribution of the neutron flux in the core region. In the coupled calculation, the high-energy cross-section library JENDL4.0/HE in ACE format produced by NJOY2016 was applied in the OpenMC transport simulation. The OECD–ADS benchmark problem was calculated, and the results were compared with those obtained using MCNPX. It was found that the flux calculations performed by FLUKA–OpenMC and MCNPX were in agreement, so the coupling calculation method for ADS is reasonable and feasible.

Preliminary physics study of the Lead–Bismuth Eutectic spallation target for China Initiative Accelerator-Driven System

The Lead-Bismuth Eutectic(LBE) spallation target has been considered as one of the two alternatives for the spallation target for China Initiative Accelerator-Driven System.This paper reports the preliminary study on physical feasibility of a U-type LBE target with window.The simulation results based on Monte Carlo transport code MCNPX indicate that the spallation neutron yield is about 2.5 per proton.The maximum spallation neutron flux is observed at about 3 cm below the lowest part of the window.When the LBE target is coupled with the reactor,the reactor neutrons from the fission reaction increased the neutron field significantly.The energy deposition of highenergy protons is the main heat source;the spallation neutrons and reactor neutrons contribute only a small fraction.The maximum energy deposition in the LBE is about 590 W/cm^3 and that in the target window is about319 W/cm^3.To estimate the lifetime of the target window,we have calculated the radiation damages.The maximum displacement production rate in the target window is about10 dpa/FPY.The hydrogen and helium production rates generated during normal operation were also evaluated.By analyzing the residual nucleus in the target during the steady operation,we estimated the accumulated quantities of the extreme radioactivity toxicant ^(210)Po in the LBE target loop.The results would be helpful for the evaluation of the target behavior and will be beneficial to the optimization of the target design work of the experimental facilities.

Transient multi-physics behavior of an insert high temperature superconducting no-insulation coil in hybrid superconducting magnets with inductive coupling

A transient multi-physics model incorporated with an electromagneto-thermomechanical coupling is developed to capture the multi-field behavior of a single-pancake(SP)insert no-insulation(NI)coil in a hybrid magnet during the charging and discharging processes.The coupled problem is resolved by means of the finite element method(FEM)for the magneto-thermo-elastic behaviors and the Runge-Kutta method for the transient responses of the electrical circuits of the hybrid superconducting magnet system.The results reveal that the transient multi-physics responses of the insert NI coil primarily depend on the charging/discharging procedure of the hybrid magnet.Moreover,a reverse azimuthal current and a compressive hoop stress are induced in the insert NI coil during the charging process,while a forward azimuthal current and a tensile hoop stress are observed during the discharging process.The induced voltages in the insert NI coil can drive the currents flowing across the radial turns where the contact resistance exists.Therefore,it brings forth significant Joule heat,causing a temperature rise and a uniform distribution of this heat in the coil turns.Accordingly,a thermally/mechanically unstable or quenching event may be encountered when a high operating current is flowing in the insert NI coil.It is numerically predicted that a quick charging will induce a compressive hoop stress which may bring a risk of buckling instability in the coil,while a discharging will not.The simulations provide an insight of hybrid superconducting magnets under transient start-up or shutdown phases which are inevitably encountered in practical applications.

Design study of charge-stripping scheme of heavy ion beams for HIAF-BRing

Charge strippers play an essential role in heavy-ion accelerators by stripping the projectile ions to higher charge states to enhance the acceleration efficiency downstream of the stripper.In the high-energy mode of the booster ring(BRing)of the high-intensity heavy-ion accelerator facility,the pre-accelerated ions from the iLinac will be stripped by a carbon foil to higher charge states and then injected into the BRing.The key parameters of the stripper and stripped ions were calculated,and the influence of stripping on the beam quality was discussed.To get high stripping efficiencies,the foil thicknesses and resultant charge state distributions for the typical ions were determined by the code ETACHA.The equilibrium thickness was obtained for the U beam,while the stripper thicknesses for the Xe and Kr beams were determined based on a compromise between the stripped charge states and the stripping efficiency.The energy loss,energy straggling,and emittance growth due to stripping have a non-negligible impact on the transport of the stripped beams and the injection of the ring.Therefore,these parameters were simulated by GEANT4.In addition,the foil’s temperature evolution,which greatly affects the foil lifetime,was simulated by ANSYS.The maximum temperature of the foil bombarded by the U and Xe beams with the nominal parameters will exceed the safe value in terms of the impact of evaporation on the foil’s lifetime.Given the foil temperature constraint,the highest tolerable beam intensity and the injected ion number into the ring were derived for different beam sizes.The results of this paper will present important reference data for the optimization design and commissioning of the beamline and injection to the BRing for the stripped ions.

Design and prototyping of the readout electronics for the transition radiation detector in the high energy cosmic radiation detection facility

The high energy cosmic-radiation detection(HERD)facility is planned to launch in 2027 and scheduled to be installed on the China Space Station.It serves as a dark matter particle detector,a cosmic ray instrument,and an observatory for high-energy gamma rays.A transition radiation detector placed on one of its lateral sides serves dual purpose,(ⅰ)calibrating HERD's electromagnetic calorimeter in the TeV energy range,and(ⅱ)serving as an independent detector for high-energy gamma rays.In this paper,the prototype readout electronics design of the transition radiation detector is demonstrated,which aims to accurately measure the charge of the anodes using the SAMPA application specific integrated circuit chip.The electronic performance of the prototype system is evaluated in terms of noise,linearity,and resolution.Through the presented design,each electronic channel can achieve a dynamic range of 0–100 fC,the RMS noise level not exceeding 0.15 fC,and the integral nonlinearity was<0.2%.To further verify the readout electronic performance,a joint test with the detector was carried out,and the results show that the prototype system can satisfy the requirements of the detector's scientific goals.

Design and high-power testing of offline conditioning cavity for CiADS RFQ high-power coupler

To validate the design rationality of the power coupler for the RFQ cavity and minimize cavity contamination,we designed a low-loss offline conditioning cavity and conducted high-power testing.This offline cavity features two coupling ports and two tuners,operating at a frequency of 162.5 MHz with a tuning range of 3.2 MHz.Adjusting the installation angle of the coupling ring and the insertion depth of the tuner helps minimize cavity losses.We performed electromagnetic structural and multiphysics simulations,revealing a minimal theoretical power loss of 4.3%.However,when the cavity frequency varied by110 kHz,theoretical power losses increased to10%,necessitating constant tuner adjustments during conditioning.Multiphysics simulations indicated that increased cavity temperature did not affect frequency variation.Upon completion of the offline high-power conditioning platform,we measured the transmission performance,revealing a power loss of 6.3%,exceeding the theoretical calculation.Conditioning utilized efficient automatic range scanning and standing wave resonant methods.To fully condition the power coupler,a 15°phase difference between two standing wave points in the condition-ing system was necessary.Notably,the maximum continuous wave power surpassed 20 kW,exceeding the expected target.

Uniformity Control of Scanned Beam in 300 MeV Proton and Heavy Ion Accelerator Complex at SESRI

In recent years,heavy ion accelerator technology has been rapidly developing worldwide and widely applied in the fields of space radiation simulation and particle therapy.Usually,a very high uniformity in the irradiation area is required for the extracted ion beams,which is crucial because it directly affects the experimental precision and therapeutic effect.Specifically,ultra-large-area and high-uniformity scanning are crucial requirements for spacecraft radiation effects assessment and serve as core specification for beamline terminal design.In the 300 MeV proton and heavy ion accelerator complex at the Space Environment Simulation and Research Infrastructure(SESRI),proton and heavy ion beams will be accelerated and ultimately delivered to three irradiation terminals.In order to achieve the required large irradiation area of 320 mm×320 mm,horizontal and vertical scanning magnets are used in the extraction beam line.However,considering the various requirements for beam species and energies,the tracking accuracy of power supplies(PSs),the eddy current effect of scanning magnets,and the fluctuation of ion bunch structure will reduce the irradiation uniformity.To mitigate these effects,a beam uniformity optimization method based on the measured beam distribution was proposed and applied in the accelerator complex at SESRI.In the experiment,the uniformity is successfully optimized from 75%to over 90%after five iterations of adjustment to the PS waveforms.In this paper,the method and experimental results were introduced.

Fully relativistic energies,transition properties,and lifetimes of lithium-like germanium

Employing two fully relativistic methods,the multi-reference configuration Dirac-Hartree-Fock(MCDHF)methodand the relativistic many-body perturbation theory(RMBPT)method,we report energies and lifetime values for the lowest35 energy levels of the(1s^(2))nl configurations(where the principal quantum number n=2-6 and the angular quantum numberl=0,...,n-1)of lithium-like germanium(Ge XXX),as well as complete data on the transition wavelengths,radiativerates,absorption oscillator strengths,and line strengths between the levels.Both the allowed(E1)and forbidden(magneticdipole M1,magnetic quadrupole M2,and electric quadrupole E2)ones are reported.The results from the two methodsare consistent with each other and align well with previous accurate experimental and theoretical findings.We assess theoverall accuracies of present RMBPT results to be likely the most precise ones to date.The present fully relativistic resultsshould be helpful for soft x-ray laser research,spectral line identification,plasma modeling and diagnosing.The datasetspresented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00113.00135.

Studies of an event-building algorithm of the readout system for the twin TPCs in HFRS

The High-energy Fragment Separator(HFRS),which is currently under construction,is a leading international radioactive beam device.Multiple sets of position-sensitive twin time projection chamber(TPC)detectors are distributed on HFRS for particle identification and beam monitoring.The twin TPCs'readout electronics system operates in a trigger-less mode due to its high counting rate,leading to a challenge of handling large amounts of data.To address this problem,we introduced an event-building algorithm.This algorithm employs a hierarchical processing strategy to compress data during transmission and aggregation.In addition,it reconstructs twin TPCs'events online and stores only the reconstructed particle information,which significantly reduces the burden on data transmission and storage resources.Simulation studies demonstrated that the algorithm accurately matches twin TPCs'events and reduces more than 98%of the data volume at a counting rate of 500 kHz/channel.

Opportunities for production and property research of neutron-rich nuclei around N=126 at HIAF

The study of nuclide production and its properties in the N=126 neutron-rich region is prevalent in nuclear physics and astrophysics research.The upcoming High-energy FRagment Separator(HFRS)at the High-Intensity heavy-ion Accelerator Facility(HIAF),an in-flight separator at relativistic energies,is characterized by high beam intensity,large ion-optical acceptance,high magnetic rigidity,and high momentum resolution power.This provides an opportunity to study the production and properties of neutron-rich nuclei around N=126.In this paper,an experimental scheme is proposed to produce neutron-rich nuclei around N=126 and simultaneously measure their mass and lifetime based on the HFRS separator;the feasibility of this scheme is evaluated through simulations.The results show that under the high-resolution optical mode,many new neutron-rich nuclei approaching the r-process abundance peak around A=195 can be produced for the first time,and many nuclei with unknown masses and lifetimes can be produced with high statistics.Using the time-of-flight corrected by the measured dispersive position and energy loss information,the cocktails produced from 208 Pb fragmentation can be unambiguously identified.Moreover,the masses of some neutron-rich nuclei near N=126 can be measured with high precision using the time-of-flight magnetic rigidity technique.This indicates that the HIAF-HFRS facility has the potential for the production and property research of neutron-rich nuclei around N=126,which is of great significance for expanding the chart of nuclides,developing nuclear theories,and understanding the origin of heavy elements in the universe.

State-selective charge exchange cross sections in collisions of highly-charged sulfur ions with helium and molecular hydrogen

The state-selective cross section data are useful for understanding and modeling the x-ray emission in celestial observations.In the present work,using the cold target recoil ion momentum spectroscopy,for the first time we investigated the state-selective single electron capture processes for S^(q+)–He and H_(2)(q=11–15)collision systems at an impact energy of q×20 keV and obtained the relative state-selective cross sections.The results indicate that only a few principal quantum states of the projectile energy level are populated in a single electron capture process.In particular,the increase of the projectile charge state leads to the population of the states with higher principal quantum numbers.It is also shown that the experimental averaged n-shell populations are reproduced well by the over-barrier model.The database is openly available in Science Data Bank at 10.57760/sciencedb.j00113.00091.

Reliability of DC-link capacitor in pulsed power supply for accelerator magnet

Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage,store energy,and decrease power variation.In this study,DC-link capacitors in pulsed power supplies were investigated.By deriving an analytical method for the capacitor current on the H-bridge topology side,the root-mean-square value of the capacitor current was calculated,which helps in selecting the DC-link capacitors.The proposed method solves this problem quickly and with high accuracy.The current reconstruction of the DC-link capacitor is proposed to avoid structural damage in the capacitor’s current measurement,and the capacitor’s hotspot temperature and temperature rise are calculated using the FFT transform.The test results showed that the error between the calculated and measured temperature increases was within 1.5℃.Finally,the lifetime of DC-link capacitors was predicted based on Monte Carlo analysis.The proposed method can evaluate the reliability of DC-link capacitors in a non-isolated switching pulsed power supply for accelerators and is also applicable to film capacitors.

Exploration of the coupled lattice Boltzmann model based on a multiphase field model:A study of the solid-liquid-gas interaction mechanism in the solidification process

A multiphase field model coupled with a lattice Boltzmann(PF-LBM)model is proposed to simulate the distribution mechanism of bubbles and solutes at the solid-liquid interface,the interaction between dendrites and bubbles,and the effects of different temperatures,anisotropic strengths and tilting angles on the solidified organization of the SCN-0.24wt.%butanedinitrile alloy during the solidification process.The model adopts a multiphase field model to simulate the growth of dendrites,calculates the growth motions of dendrites based on the interfacial solute equilibrium;and adopts a lattice Boltzmann model(LBM)based on the Shan-Chen multiphase flow to simulate the growth and motions of bubbles in the liquid phase,which includes the interaction between solid-liquid-gas phases.The simulation results show that during the directional growth of columnar dendrites,bubbles first precipitate out slowly at the very bottom of the dendrites,and then rise up due to the different solid-liquid densities and pressure differences.The bubbles will interact with the dendrite in the process of flow migration,such as extrusion,overflow,fusion and disappearance.In the case of wide gaps in the dendrite channels,bubbles will fuse to form larger irregular bubbles,and in the case of dense channels,bubbles will deform due to the extrusion of dendrites.In the simulated region,as the dendrites converge and diverge,the bubbles precipitate out of the dendrites by compression and diffusion,which also causes physical phenomena such as fusion and spillage of the bubbles.These results reveal the physical mechanisms of bubble nucleation,growth and kinematic evolution during solidification and interaction with dendrite growth.

Experimental study on the gas-stripping chamber of an E//B neutral particle analyzer

Stripping units take a key role in the neutral particle analyzer(NPA).A renovated gas-stripping unit was constructed for the newly designed E//B NPA.Using H_(2)as the working gas,we measured the gas inlet pressure(P_(0))and vacuum chamber pressure(P_(3)).The pressure distribution inside the gas-stripping room was calculated with Ansys Fluent,using the measured P_(0)and P_(3)as boundary conditions.The stripping efficiency of the stripping unit was then simulated utilizing the Geant4 Monte Carlo code for the H and D particles.The pressure P_(0)=40 Pa,which is one-sixth of what found in the previous design and corresponds to a thickness of 1.27×10^(17)atoms∕cm^(2),was obtained as the optimum working pressure for the upgraded stripping unit.An 50 kV electron cyclotron resonance(ECR)ion source platform was designed and constructed for E//B NPA calibration,and its performance has been measured.Using the ECR ion source platform,we measured the efficiency of the stripping unit through an inverse experiment with proton beams.We compared the current ratios of measurements with and without H_(2)gas to Geant4 simulation results.We found adequate agreement between the overall trends of the experiment and the simulation.The significant deviation for incident energies below 20 keV may result from the scattering effects of low-energy protons,leading to reduced accuracy in single-scattering physics in Geant4 simulations.Applying the scattering corrections observed in the reverse experiments obtains more accurate stripping efficiencies for H and D atoms in the energy range of 20–200 keV and the global efficiency with the maximum values of 95.0%for H atoms and 78.9%for D atoms at 200 keV.

Two-dimensional particle-in-cell modeling of blow-off impulse by X-ray irradiation

Space objects such as spacecraft or missiles may be exposed to intense X-rays in outer space,leading to severe damage.The reinforcement of these objects to reduce the damage caused by X-ray irradiation is a significant concern.The blow-off impulse(BOI)is a crucial physical quantity for investigating material damage induced by X-ray irradiation.However,the accurate calculation of BOI is challenging,particularly for large deformations of materials with complex configurations.In this study,we develop a novel two-dimensional particle-in-cell code,Xablation2D,to calculate BOIs under far-field X-ray irradiation.This significantly reduces the dependence of the numerical simulation on the grid shape.The reliability of this code is verified by simulation results from open-source codes,and the calculated BOIs are consistent with the experimental and analytical results.

Simulation of nuclear isomer production in laser-induced plasma

Nuclear isomers play essential roles in various fields,including stellar nucleosynthesis,nuclear clocks,nuclear batteries,clean nuclear energy,and-ray lasers.Recent technological advances in high-intensity lasers have made it possible to excite or de-excite nuclear isomers using table-top laser equipment.Utilizing a particle-in-cell code,we investigate the interaction of a laser with a nanowire array and calculate the production rates of the^(73m)Ge(E_(1)=13.3 keV)and^(107m)Ag(E_(1)=93.1 keV)isomers.For^(73m1)Ge,production by Coulomb excitation is found to contribute a peak efficiency of 1.0×10^(19) particles s^(−1)J^(−1),while nuclear excitation by electron capture(NEEC)contributes a peak of 1.65×10^(11)particles s^(−1)J^(−1).These results indicate a high isomeric production ratio,as well as demonstrating the potential for confirming the existence of NEEC,a long-expected but so far experimentally unobserved fundamental process.

Estimating the yield stress of soft materials via laser-induced breakdown spectroscopy

Taking three typical soft samples prepared respectively by loose packings of 77-,95-,and 109-μm copper grains as examples,we perform an experiment to investigate the energy-dependent laser-induced breakdown spectroscopy(LIBS)of soft materials.We discovered a reversal phenomenon in the trend of energy dependence of plasma emission intensity:increasing initially and then decreasing separated by a well-defined critical energy.The trend reversal is attributed to the laser-induced recoil pressure at the critical energy just matching the sample's yield strength.As a result,a one-to-one correspondence can be well established between the samples'yield stress and the critical energy that is easily obtainable from LIBS measurements.This allows us to propose an innovative method for estimating the yield stress of soft materials via LIBS with attractive advantages including in-situ remote detection,real-time data collection,and minimal destructive to sample.

Discontinuities of Banana Integrals in Dispersion Relation Representation

We derive the discontinuities of banana integrals using the dispersion relation iteratively,and find a series of identities between the parameterized discontinuities of banana integrals(p-DOBIs).Similar to elliptic integrals,these identities enable the reduction of various p-DOBIs to be a linear combination of some fundamental ones.We present a practical application of p-DOBIs for deriving the Picard–Fuchs operator.Then we establish the expression of generalized dispersion relation,which enables us to obtain the dispersion relation representation of arbitrary banana integrals.Moreover,we propose a hypothesis for generalized dispersion relation and p-DOBIs,which provides a simple way to calculate the discontinuities and transform dispersion relation representation to p-DOBIs.

Construction and performance test of charged particle detector array for MATE

A charged particle array named MATE-PA,which serves as an auxiliary detector system for a Multi-purpose Active-target Time projection chamber used in nuclear astrophysical and exotic beam Experiments(MATE),was constructed.The array comprised of 20 single-sided strip-silicon detectors covering approximately 10%of the solid angle.The detectors facilitated the detection of reaction-induced charged particles that penetrate the active volume of the MATE.The performance of MATE-PA has been experimentally studied using an alpha source and a 36-MeV 14 N beam injected into the MATE chamber on the radioactive ion beam line in Lanzhou(RIBLL).The chamber was filled with a gas mixture of 95%4 He and 5%CO_(2) at a pressure of 500 mbar.The results indicated good separation of light-charged particles using the forward double-layer silicon detectors of MATE-PA.The energy resolution of the Si detectors was deduced to be approximately 1%(σ)for an energy loss of approximately 10 MeV caused by theαparticles.The inclusion of MATE-PA improves particle identification and increases the dynamic range of the kinetic energy of charged particles,particularly that of theαparticles,up to approximately 15 MeV.