Ion Research Facility In Lanzhou Research Articles

Influence of different fields of mesons on the pseudospin symmetry in single-neutron resonant states * *Supported by the National Natural Science Foundation of China (11935001, 11805004), the Key Research Foundation of Education Ministry of Anhui Province (KJ2018A0028), the Natural Science Foundation of Anhui Province (2008085MA26) and Heavy Ion Research Facility in Lanzhou (HIRFL)

In the framework of the relativistic mean field theory combined with the complex momentum representation method, we elucidate the pseudospin symmetry in the single-neutron resonant states and its dependence on the , , and meson fields. Compared with the effect of the field, the and fields provide the main contributions to the pseudospin energy and width splitting of the resonant pseudospin doublets. Especially, we compare quantitatively the pseudospin wave functions' splittings in resonant doublets, and investigate their dependencies on different fields of mesons, which is consistent with that of energy and width splittings. Current research is helpful to understand the mechanism and properties of pseudospin symmetry for resonant states.

Readout Electronics Prototype of TOF Detectors in CEE of HIRFL

In the Cooling storage ring External-target Experiment (CEE) in heavy ion research facility in Lanzhou (HIRFL), multigap resistive plate chambers (MRPCs) detectors are used for high-precision time-of-flight (TOF) measurement to identify the scattered particles after the ion beam hits the target. Regarding the external TOF (eTOF) and 2/3 internal TOF (iTOF) detectors, a ~25-ps rms time precision is required for the readout electronics, whereas for the other 1/3 iTOF detectors, a ~10-ps rms precision is required. A readout electronics prototype was designed, including the front-end electronics (FEE) based on analog signal amplification, discrimination, and the time-to-digital module (TDM), based on field-programmable gate array (FPGA) time-to-digital converter (TDC), to achieve high-precision time measurement. PreAmplifier-DIscriminator (PADI) is used in the design of the FEE, while an FPGA TDC, based on tapped delay line (TDL) structure, with a time precision performance better than 5-ps rms, is implemented in the TDM, as well as the trigger matching circuit and other control logic. The performance of the whole system was tested under different input signal charges and the results indicated that the time precision is better than 10-ps rms, which satisfies the application requirements.

β-decay and isospin symmetry breaking

<p indent=0mm>The elegant concept of isospin symmetry is of fundamental importance in nuclear and elementary particle physics. As a β-decay process changes an up quark to a down quark or <italic>vice versa</italic>, studies of nuclei with exchanged numbers of neutrons and protons, known as mirror nuclei, can be a powerful means to probe isospin symmetry breaking. A series of β-decay experiments of sd-shell nuclei near the proton drip line produced by projectile fragmentation were performed at the Radioactive Ion Beam Line of the Heavy Ion Research Facility in Lanzhou (HIRFL-RIBLL1) using a silicon array with a high detection efficiency and a low detection threshold. The secondary ions were identified by the combination of Δ<italic>E</italic>-TOF and magnetic rigidity (<italic>Bρ</italic>) in which the time of flight (TOF) was measured by two plastic scintillators at the second and fourth focal planes of the RIBLL1 and the energy loss (Δ<italic>E</italic>) was measured by two silicon detectors in the front of the silicon array. Double-sided silicon strip detectors (DSSDs) in the center of the array served to measure the residual energies of secondary ions on an event-by-event basis and study their decay properties with an implantation-decay correlation. Several quadrant silicon detectors (QSDs) placed behind DSSDs were used for anticoincidences of the penetrating fragments and light particles coming along with the beam, and measurements of β particles and high-energy protons. The β-delayed proton peaks with known energies and their corresponding absolute intensities were used for the energy and detection efficiency calibrations of the DSSDs. The system allows us to measure protons with energies down to about <sc>200 keV</sc> without obvious β background in the proton spectrum and was successful to measure the energies, time, and positions of implanted ions and decay protons efficiently, supporting researchers to study the decay properties of nuclei towards the proton drip line. The β-decay data, together with the large-scale shell-model calculations, allows detailed investigations on the mirror-nuclei systems resulting in the systematic study of isospin symmetry breaking in the sd-shell nuclear region. It was found that the mirror asymmetry parameters become larger due to the smaller separation energies while approaching the proton drip line for the extremely proton-rich sulfur nuclei ^27,28,29S and the Coulomb forces and other isospin-symmetry nonconserving forces acting between protons would lead to extended proton wave functions and cause mirror asymmetries. The properties of ²²Si β-decay for the transitions to the low-lying states of ²²Al were measured, and the reduced transition probabilities were determined. Comparing with the data on the β-decay of the mirror nucleus ²²O, we found a mirror asymmetry of <italic>δ</italic>=209(96)% in the transition to the first 1⁺ excited state of the respective daughters. This is by far the largest value of <italic>δ</italic> observed in the low-lying states. Shell-model calculations with isospin-nonconserving forces, including the <italic>T</italic>=1,<italic> J</italic>=2, 3 interactions related to the s_1/2 orbit that introduces explicitly the isospin-symmetry breaking force and describes the loosely bound nature of the wave functions of the s_1/2 orbit, can reproduce the observed data well and demonstrate that this dramatically large mirror asymmetry is attributed to the significant proton occupation and loosely bound nature of the wave functions of the s_1/2 orbit, which suggests that ²²Al is a proton-halo nucleus.

Microstructure evolution of T91 steel after heavy ion irradiation at 550 °C* *Project supported by Guangdong Major Project of Basic and Applied Basic Research (Grant No. 2019B030302011), the National Natural Science Foundation of China (Grant Nos. U2032143, 11902370, and 52005523), the International Science and Technology Cooperation Program of Guangdong Province, China (Grant No. 2019A050510022), the China Postdoctoral Science Foundation (Grant

Fe-Cr ferritic/martensitic (F/M) steels have been proposed as one of the candidate materials for the Generation IV nuclear technologies. In this study, a widely-used ferritic/martensitic steel, T91 steel, was irradiated by 196-MeV Kr+ ions at 550 °C. To reveal the irradiation mechanism, the microstructure evolution of irradiated T91 steel was studied in details by transmission electron microscope (TEM). With increasing dose, the defects gradually changed from black dots to dislocation loops, and further to form dislocation walls near grain boundaries due to the production of a large number of dislocations. When many dislocation loops of primary a 0/2〈 111 〉 type with high migration interacted with other defects or carbon atoms, it led to the production of dislocation segments and other dislocation loops of a 0 〈 100 〉 type. Lots of defects accumulated near grain boundaries in the irradiated area, especially in the high-dose area. The grain boundaries of martensite laths acted as important sinks of irradiation defects in T91. Elevated temperature facilitated the migration of defects, leading to the accumulation of defects near the grain boundaries of martensite laths.

Progress on internal gas-jet target nuclear reaction at the HIRFL-CSR

Direct nuclear reactions induced by light ions, e.g., proton and alpha particles, have been investigated for about a century since the Geiger-Marsden experiment in 1908. It provides important information on nuclear structure and nuclear astrophysics. For instance, neutron skin thicknesses of nuclei determined by using proton and α elastic scattering play an important role in constraining the equation of state (EOS) of isospin asymmetric nuclear matter. These reactions were mostly conducted in direct kinematics, that is to say, the light-ion beam from accelerator interacts with a target made of the nuclei of interest. Obviously, such kinds of experimental investigations are limited to stable solid isotopes without active chemical property and radioactivity, due to the difficulty to make unstable targets. To test theoretical models developed from stable nuclei and explore new physical phenomenon on exotic nuclei, it is essential to investigate direct reactions on nuclei far from stability. As a result, experimental method based on inverse kinematics, namely active gas target technique, has been developed, where the unstable nuclei of interest produced by radioactive ion beam facilities collide with hydrogen and helium gases in a bubble chamber. The direct reactions are performed in inverse kinematics. One advantage is that low energy recoils at small center of mass angles can be measured easily at relatively large laboratory angles. However, this experimental method is insensitive to detect scattering recoils with energies of a few hundred keV, due to measurement based on gas detector. In recent years, a novel experimental method, namely study with stored beam in storage ring interacting with internal gas-jet target, has attracted much interest. It was proposed firstly for the exotic nuclei studied with light-ion induced reactions in storage rings (EXL) project. The technique is based on the internal gas-jet target instead of active gas target. It is an important supplementary experiential method for studying direct nuclear reactions induced by light ions, which is characterized by low-momentum sensitivity, high detection efficiency and low background. It is an ideal tool to study the isotopes with active chemical property and radioactivity. The cooler storage ring at the heavy ion research facility in Lanzhou (HIRFL-CSR) consists of a main cooler storage ring (CSRm) and an experimental cooler storage ring (CSRe). The two rings are connected by a radioactive ion beam line 2 (RIBLL2). The CSRe is equipped with an internal gas-jet target. As one of the existing facilities, the HIRFL-CSR provides an opportunity for performing in-ring direct nuclear reactions induced by light ions with the internal gas-jet target. Since 2016, a silicon strip detector compatibility with ultra-high vacuum in heavy-ion storage ring has been developed to build the in-ring direct nuclear reaction spectrometry at the HIRFL-CSR. A feasibility experiment on proton elastic scattering on 58Ni nuclei has been operated successfully by using the in-ring nuclear reaction spectrometry at the HIRFL-CSR. The nuclear matter distribution radius of 58Ni was extracted from measured differential cross sections at low momentum transfer. Proton elastic scattering experiment on 78Kr nuclei was also carried out to extract the nuclear matter radius at the beginning of 2021. In this paper, we report the development of in-ring direct nuclear reaction spectrometry at the HIRFL-CSR and corresponding experiments. Research plans in the (near) future, especially for measuring nuclear matter distribution radius of 133Cs, are also introduced.

X-rays produced by interaction of Xe&lt;sup&gt;20+&lt;/sup&gt; with different targets in Bragg peak energy region

&lt;sec&gt;The inner shell process produced by the collision of highly charged ion with medium atoms near the Bragg peak is an important frontier area of atomic physics under extreme conditions such as celestial plasmas and controlled nuclear fusion plasmas. Because of the special complexity of the inner shell process produced by the collision of ions with atoms in the Bragg peak energy region and the relevant experimental research is less, limited by the experimental conditions, there remain some interesting and unanswered questions.&lt;/sec&gt;&lt;sec&gt;We report the experimental data of X-ray spectra produced by the impact of Xe&lt;sup&gt;20+&lt;/sup&gt; with 6.0 MeV kinetic energy on V, Fe, Ni, Cu, and Zn surface in the National Laboratory of Heavy Ion Research Facility in Lanzhou, China. The generation mechanism of X-ray with energy of 1.60 keV is analyzed. The results show that when Xe&lt;sup&gt;20+&lt;/sup&gt; without initial holes interacts with different targets, the Mα X-ray of Xe is not observed, but X-ray with energy twice as great as that of Xe Mα X-ray is observed in the experiment, which is called Xe Mαα X-ray and considered to be generated by the two-electron-one-photon process of Xe on the upper surface of the target. The existence time of the first-generation hollow atoms on the upper surface is calculated by using the classical over-barrier model when Xe&lt;sup&gt;20+&lt;/sup&gt; interacts with different targets, which is consistent with the variation of Mαα X-ray yield with the atomic number of target, therefore it is further proved that Mαα X-ray is formed by the two-electron one-photon process of Xe on the upper surface of the target. Of course, this conclusion needs further analyzing and verifying with more experimental data.&lt;/sec&gt;

Introduction of the Heavy Ion Research Facility in Lanzhou (HIRFL)

The Heavy Ion Research Facility in Lanzhou (HIRFL) is a multi-disciplinary research facility that provides heavy ion beams for physical, biomedical and material sciences. It is a major academic facility of China and one of the world's important centers in nuclear physics and accelerators. The facility was built step by step at Institute of Modern Physics (IMP) over a half century. The first cyclotron was built with great assistance from the former Soviet Union in 1960s, and the newest linear accelerator was tested successfully in 2019. The HIRFL accelerator can provide beams from proton to Uranium with energies of hundreds MeV/u, and hence diverse fundamental sciences and applied researches were carried out at IMP. In this paper, an introduction of the HIRFL accelerator complex was presented. Details of the HIRFL components including ion sources, cyclotrons, synchrotrons, linac and experimental terminals were described. The current operation status and upgrade plans were reported.

Major Accelerator Facilities for Nuclear Physics in Asia Pacific

Asian Nuclear Physics Association (ANPhA) is the central organization representing nuclear physics in Asia Pacific. ANPhA is now preparing a list of accelerators applicable for nuclear physics experiments in Asia Pacific. Among the listed facilities, world-class “major” accelerator facilities are mainly located in China (Heavy Ion Research Facility in Lanzhou (HIRFL), and its future extension in Huizhou, i.e. HIAF/CiADS, Beijing Tandem Accelerator National Laboratory (BTANL), which is now upgraded to Beijing RI beam Facility (BRIF), in India (Variable Energy Cyclotron Centre (VECC) in Kolkata), in Korea (RISP/rAoN), and in Japan (RIBF at Riken, J-PARC, RCNP, and ELPH/LEPS). World class facilities based on the tandem accelerator are locating at Mumbai and New Deli in India, at Tokai-mura in Japan, and at Canberra in Australia. Characteristics of these “majof” facilities including their facility developments will briefly be reviewed in comparing with similar facilities in Europe and North America.

A noninvasive Ionization Profile Monitor for transverse beam cooling and orbit oscillation study in HIRFL-CSR

A noninvasive Ionization profile monitor (IPM) consisting of micro-channel plates, a phosphor screen and the optical-signal acquisition has been developed at the cooling storage ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). It makes the real-time profile measurements for the transverse beam cooling and orbit oscillation possible and efficient. This paper firstly describes all the IPM design criterions including the theoretical signal yield calculation, the space charge field and initial momentum evaluation, and the electrostatic field distortion simulation as well. In order to investigate the IPM performance, the beam profile measurements are done with different high voltage settings. Subsequently, some valuable beam experiments about the transverse electron cooling and orbit oscillation study are also presented. In the end, fast turn-by-turn profile measurements for the emittance blow-up research in a synchrotron are discussed. In cooperation with the newly deployed emittance instruments at the HIRFL-CSR injector, the IPM shows great prospects for the injection mismatch study, and potential values for the tune, dispersion and chromaticity measurements as well.

Relativistic eigenchannelR-matrix studies of the strong intrashell electron correlations in highly chargedAr13+ions

Highly charged ion systems play an important role in simulation and diagnostics of astrophysical and fusion plasmas. Due to dominant strong Coulomb interactions from the nuclear charge, electron correlations are generally thought to be less prominent than relativistic effects and other effects in HCIs. In this paper, we demonstrate the importance of strong intrashell electron correlations from the quasidegeneracy of $2s, 2p$ orbitals in highly charged B-like ${\mathrm{Ar}}^{13+}$ ions. Such strong intrashell electron interactions manifest as an atomic system with many channel interactions, which will ultimately form a much more complex atomic spectrum than the neutral B atom in the isoelectronic sequence. As a typical example, the relativistic eigenchannel $R$-matrix method (R-R-eigen code) was successfully applied to investigate the complex spectrum of ${\mathrm{Ar}}^{13+}$ ions with ${J}^{\ensuremath{\pi}}=1.{5}^{+}$ symmetry in discrete and autoionization regions. Calculated results obviously show interesting behaviors of strong intrashell electron correlations in HCIs. Additionally, it is also beneficial to understand discrepancies in the low-energy electron-ion recombination spectra of Be-like ${\mathrm{Ar}}^{14+}$ ions between experimental observations at the main cooler-storage ring of the Heavy Ion Research Facility in Lanzhou and distorted wave calculation.

Experimental study of tritium activity concentration in cooling water of heavy ion research facility in Lanzhou

Cooling water of Heavy Ion Research Facility in Lanzhou is the media of choice for absorbing heat generated by a multitude of accelerator components. During the operation, tritium is produced by the secondary neutrons in the accelerator loop of accelerator cooling water, which is uniformly distributed in the water system in the form of hydrogen tritium oxide. The purpose of this study is to establish a rigorous method to measure the low levels of tritium in the accelerator cooling water system. The cooling water samples of Sector Focusing Cyclotron and Separated Sector Cyclotron of Heavy Ion Research Facility in Lanzhou, as well as the natural levels of tritium, were measured successfully, using Quantulus1220 ultra-low-level background liquid scintillation spectrometer. The electrolytic enrichment method was employed to measure the tritium activity concentrations of the cooling water samples. Moreover, the minimum detectable activity concentration and the counting rate efficiency curve of the liquid scintillation spectrometer were obtained to ensure reliability. In this work, we provide a reference to establish the related standards and specifications for monitoring the tritium levels in heavy-ion accelerator cooling water system.

Present status of HIRFL complex in Lanzhou

Heavy Ion Research Facility in Lanzhou (HIRFL) is a cyclotron, synchrotron and storage ring accelerator complex, which accelerates ions of hydrogen to uranium from low to medium energy. Since the complete of HIRFL-CSR project in 2008, under the support from CAS, efforts have been put to improve the infrastructure for machine performance, including improvement of EMC environments, power distribution stations, PS stations, cooling water system, RF system of cyclotrons and adoption of EPICS control system, etc. New generation SC ECR source (SECRAL-II) with high performance is put into operation. Experiments of electron cooling with pulsed electron beam are performed for the first time. Stochastic cooling and laser cooling are realized in CSRe. The performance of RIBLL2 and CSRe are gradually improved. The isochronous mode of CSRe for precise atomic mass measurements is well studied and reaches state-of-art mass resolution of storage rings. The operation status and enhancement plan of HIRFL will be briefly reported in this paper.

&lt;sup&gt;129&lt;/sup&gt;Xe&lt;sup&gt;&lt;i&gt;q&lt;/i&gt;+&lt;/sup&gt; induced near-infrared light and X-ray emission at Cu surface

During the interaction of highly charged ions with solid target in the energy region near the Bohr velocity, the potential energy of the projectiles will be deposited on a nanometer-scale target surface within the time on the order of femtoseconds. That will lead the target atoms to be ionized into ions and the ions to be excited, resulting in the multiple ionization states and the complex configuration of energy levels. The de-excitation radiations of these levels cover the radiations from near-infrared spectral line to X-ray. Investigation of these spectral lines is significant for investigating the mechanism of such an interaction, diagnosing plasma and studying astrophysics. The experimental results show that the near-infrared spectral lines and X-ray spectra are produced by the &lt;sup&gt;129&lt;/sup&gt;Xe&lt;i&gt;&lt;sup&gt;q&lt;/sup&gt;&lt;/i&gt;&lt;sup&gt;+&lt;/sup&gt; (&lt;i&gt;q&lt;/i&gt; = 21, 23, 25, 27) with kinetic energy of 1360 keV and &lt;sup&gt;129&lt;/sup&gt;Xe&lt;sup&gt;20+&lt;/sup&gt; with kinetic energy of 4 MeV impacting on the Cu surface, separately. The experiment is carried out in the National Laboratory of Heavy Ion Research Facility in Lanzhou, HIRFL. The beam intensity is on the order of nA. The highly charged ions capture the electrons of the Cu target and thus being neutralized in a femtosecond time. The energy of the highly charged ions is deposited on the target surface, and the target atoms are excited or ionized, resulting in the transition between complex configurations, such as the dipole forbidden transition (magnetic dipole and quadrupole transition) and magnetic dipole transition of the Cu&lt;sup&gt;22+&lt;/sup&gt;. The infrared spectral lines of the atoms and ions from deexcitation radiation are measured. With the 4 MeV &lt;sup&gt;129&lt;/sup&gt;Xe&lt;sup&gt;20+ &lt;/sup&gt;ions impacting on solid Cu surfsce, the X-rays are measured, such as, the magnetic dipole deexcitation radiation transition of Cu&lt;sup&gt;22+&lt;/sup&gt;, the X-rays of the L&lt;sub&gt;1&lt;/sub&gt; edge transition and L&lt;sub&gt;&lt;i&gt;β&lt;/i&gt;3&lt;/sub&gt; of the Cu I, L&lt;i&gt;&lt;sub&gt;η&lt;/sub&gt;&lt;/i&gt; and L&lt;sub&gt;&lt;i&gt;β&lt;/i&gt;3&lt;/sub&gt; X-rays of the Xe ions. The results show that during the neutrilization of highly charged Xe ions with lower energy above the Cu surface, the infrared lines are mainly from the deexcitation of the incident ions and the ionized or excited target atoms. The increasing trend of the the single ion fluorescence yield of the infrared spectral line is the same as that of the potential energy of the projectile. The characteristic L X-rays of the Xe atom are emitted by the second generation of hollow atoms formed below the surface.

Simulation and prototype testing of multi-wire drift chamber arrays for the CEE

The building of a large-scale external-target experiment, abbreviated as CEE, in the cooling storage ring at the Heavy Ion Research Facility in Lanzhou has been planned. The CEE is a multi-purpose spectrometer that will be used for various studies on heavy-ion collisions. A multi-wire drift chamber (MWDC) array is the forward tracking detector of the CEE. In this work, GEANT4 simulations were performed for the MWDC forward tracking array with a focus on the track reconstruction algorithm. Combined with the time of flight information, particle identification is achieved. The residue is about $$30\,\upmu \hbox {m}$$, while the tracking efficiency is higher than 90% with the current redundancy. In addition, a prototype of the forward tracking system using three MWDCs was assembled and tested using a high-energy proton beam. The firing efficiency of the detector and the reconstruction accuracy of the prototype were derived. The track residue for the protons at about 400 MeV/c is better than $$300\,\upmu \hbox {m}$$, meeting the requirements of the CEE. Suggestions for improving the performance of the forward tracking system are given.

Design of a fast-stop centroid finder for Monolithic Active Pixel Sensor

The heavy-ion experiments at the Heavy Ion Research Facility in Lanzhou (HIRFL) and the future High-Intensity Heavy-Ion Accelerator Facility (HIAF) in China drives the development of Monolithic Active Pixel Sensor (MAPS) for particle tracking detectors. To reduce the data volume from the MAPS based detectors, a centroid finder that can calculate the geometric centroid of the region of the energy deposition quickly has been designed. The centroid calculation is realized by distance screening among the coordinates of the pixels in the fired region. Performance study with the data from heavy-ion experiments in HIRFL proves that the centroid finder can accurately find the centroids and reduce the data volume from the MAPS by approximately one order of magnitude.

Measurement of Ni58(p,p)Ni58 elastic scattering at low momentum transfer by using the HIRFL-CSR heavy-ion storage ring

The very first in-ring reaction experiment at the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR), namely proton elastic scattering on stable $^{58}\mathrm{Ni}$ nuclei, is presented. The circulating $^{58}\mathrm{Ni}^{19+}$ ions with an energy of 95 MeV/u were interacting repeatedly with an internal hydrogen gas target in the experimental storage ring (CSRe). Low-energy proton recoils from the elastic collisions were measured with an ultra-high vacuum compatible silicon-strip detector. Deduced differential cross sections were normalized by measuring $k$-shell x rays from $^{58}\mathrm{Ni}^{19+}$ projectiles due to the $^{58}\mathrm{Ni}^{19+}\text{\ensuremath{-}}{\mathrm{H}}_{2}$ ionization collisions. Compared to the experimental cross sections, a good agreement has been achieved with the theoretical predictions in the measured region, which were obtained by using the global phenomenological optical model potentials. Our results enable new research opportunities for optical model potential studies on exotic nuclides by using the in-ring reaction setup at the HIRFL-CSR facility.

Recent progress in nuclear data measurement for ADS

Recent progress in nuclear data measurement for ADS at IMP is reviewed briefly. Based on the Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR), the nuclear data terminal was established, which mainly includes neutron time-of-flight spectrometer, light charged particles spectrometer and water-bath neutron activation setup. A number of experiments have been conducted in the nuclear data terminal.The experiments of 400 MeV/u $^{16}$O bombarded on tungsten target and lead target, 296 MeV deutron bombarded on lead target and thick beryllium target, 250 MeV protons incident on a thick grain-made tungsten target and a thick solid lead target using the water-bath neutron activation method were performed in the nuclear data terminal.The nuclear data of neutron yields, energy or time spectrum, double differential cross section and so on have been investigated.On the other hand, based on the neutronics integral experimental setup at China Institute of Atomic Energy, benchmarking of evaluated nuclear data libraries was performed on ADS relevant materials gallium, graphite, silicon carbine, tungsten, uranium samples and so on.ENDF/B-VII.1, CENDL-3.1, JENDL-4.0, JEFF-3.2 and TENDL-2015 libraries were validated.

The development of in-ring reaction measurements at the HIRFL-CSR

Abstract The present paper describes the development of in-ring reaction measurements at the Cooler-Storage Ring of the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). A Silicon (Si) detector has been developed with cost-efficient methods to meet the requirements of Ultra-High Vacuum (UHV) conditions in a storage ring. The UHV-Si detector and luminosity monitor Si(Li) detector were installed at the experimental cooler storage ring (CSRe). The pilot in-ring reaction experiment about proton elastic scattering on 58Ni 19 + ions has been operated successfully with the basic detector system in inverse kinematics , which opens an opportunity for in-ring reaction measurements at the HIRFL-CSR. This is an important step towards realizing in-ring reaction measurements with large Si detector arrays at the next generation High Intensity heavy ion Accelerator Facility (HIAF).

Heavy-ion induced radiation effects in 50 nm NAND floating gate flash memories

Using the 86Kr, 129Xe and 209Bi ions provided by the Heavy Ion Research Facility in Lanzhou (HIRFL), the short-term and long-term radiation effects induced by heavy ions induced in 50 nm NAND floating gate (FG) flash memories are investigated. The linear energy transfer (LET) value covers the range from 20.7 to 99.8 MeV·cm2/mg. Only upset errors in FG cells are observed due to that the flash memories are powered off and the peripheral circuitries are shielded during heavy ion irradiation. The errors in FG cells irradiated with ions of different LET values are decreasing with time under room temperature condition. After the reprogramming of flash memories, retention errors in FG cells are observed in some flash memories, which are irradiated by heavy ions with LET values greater than 37.6 MeV·cm2/mg. The dependence of single event upset, annealing of errors and retention errors in FG cells on the ion LET value is analysed and the underlying mechanisms are discussed.

Phase stabilization design for radio-frequency system of the IMP HIRFL-SSC

Abstract The Radio Frequency (RF) system at the Heavy Ion Research Facility in Lanzhou of the Institute of Modern Physics was upgraded to a digital low-level radio frequency system. The key part is the phase and amplitude negative feedback system based on Digital Signal Processing (DSP) and a Field Programmable Gate Array (FPGA). This paper mainly introduces the design of the phase stabilization loop, including the principle designs for phase stabilization, loop filter design, parameter calculation, and hardware. In order to improve the performance and stability of the system, the loop filter was designed by means of zero-pole cancellation. In this paper, the derivation of the “zero pole cancellation method” is introduced in detail. The implementation structure of the loop filter in the FPGA is an ingenious design that can be applied to RF systems with different cavity loaded quality factor ( Q L ) values. For different RF systems, the parameters of proportional integral (PI) algorithm are fixed, and only one parameter Q L needs to be set. An economical compensation method for the temperature drift in the pick-up cables was designed to improve the control accuracy of the system. The phase control system was tested in long-term stability experiments, and the results show that the system has excellent phase stability over the long term, as well as parasitic phase modulation suppression.