Ion Beam Line In Lanzhou Research Articles

Elastic scattering of 13C and 14C isotopes on a 208Pb target at energies of approximately five times the Coulomb barriers* *Supported by the National Natural Science Foundation of China (12122511, 12105330), the Youth Innovation Promotion Association CAS (2020411), and funding from the State Key Laboratory of Nuclear Physics and Technology, Peking University (NPT2023KFY04). V. G. would like to thank CNPq

The elastic scattering angular distributions of C at 340 MeV and C at 294 MeV and 342 MeV on a Pb target, which correspond to approximately five times the Coulomb barriers, were measured at the Radioactive Ion Beam Line in Lanzhou. The data were analyzed within the optical model and continuum-discretized coupled-channels (CDCC) framework, and the results of both calculations could effectively account for the experimental data. The differential cross sections of elastic scattering revealed no particular suppression at the Coulomb nuclear interference peak angles, suggesting that the breakup coupling effects on the elastic scattering angular distributions were negligibly small in this incident energy region. The contributions from the couplings with inelastic states to the elastic cross sections were of minor importance within the angular range covered by these experiments.

Charge-changing cross section measurements of 300 MeV/nucleon 28Si on carbon and data analysis* *Supported by the National Natural Science Foundation of China (U1832211, 11961141004, 11922501, 11475014, 11905260), the Western Light Project of Chinese Academy of Sciences, and the Natural Science Foundation of Anhui Province, China (2008085MA17)

Charge-changing cross section () measurements via the transmission method have recently seen significant progress with the aim of determining the charge radii of exotic nuclei. In this work, we report a new measurement of 304(9) MeV/nucleon Si on carbon at the second Radioactive Ion Beam Line in Lanzhou (RIBLL2) and describe the data analysis procedure in detail. This procedure is essential for evaluating the systematic uncertainty in the transmission method. The determined of 1125(11) mb is found to be consistent with the existing data at similar energies. The present work will serve as a reference for determinations at RIBLL2.

A prototype of beam profile measurement system for HIAF-HFRS beam line

ABSTRACT A prototype of beam profile measurement system developed by the Institute of Modern Physics, which can work in the proportional region and ionization region, respectively, by adjusting the pressure and voltage, has been tested several times and achieved the design expectation. When the working pressure of the detector is low enough, the system can work in the secondary electron mode to measure the fast extraction beam profile too. The measurement system has been used to measure the profile of carbon ion beam in the Second Radioactive Ion Beam Line in Lanzhou in slow extraction mode and fast extraction mode, respectively. It is confirmed that the measurement system can measure the profile of carbon ion beam with a dynamic range of beam intensity up to six orders of magnitude. We used the X-ray beam to simulate the Gaussian-like distribution for laboratory testing, and the results show that the measurement system has a better resolution than 0.1 mm for the beam position with a Sigma of about 1.6 mm. This measurement system, together with the harps measurement system, will be able to meet needs of most beam profile measurements in High energy Fragment Separator (HFRS) at High Intensity heavy-ion Accelerator Facility (HIAF).

Elastic scattering investigation of radioactive B13 and O13 projectiles on a Pb208 target at intermediate energies

Elastic scattering measurements were performed for the proton drip-line nucleus $^{13}\mathrm{O}$ (with ${S}_{p}=1.512$ MeV) and its partner mirror nucleus $^{13}\mathrm{B}$ (with ${S}_{n}=4.878$ MeV) projectiles on a $^{208}\mathrm{Pb}$ target at intermediate energies, namely ${E}_{\mathrm{lab}}=413$ and 254 MeV, respectively. These secondary radioactive ion beams were produced at the Radioactive Ion Beam Line in Lanzhou (RIBLL), Heavy-Ion Research Facility in Lanzhou (HIRFL). The elastic scattering angular distributions for these projectiles show a typical Fresnel diffraction peak at forward angles. Optical model analyses of the angular distributions, using double-folding and global potentials, were performed and different densities for these projectiles were probed.

Design and performance of micro-channel plate based particle tracking detector for astrophysical ([formula omitted], p) reactions

The micro-channel plate based particle tracking detector described here is part of the detector system used in a series of measurements of astrophysical (α, p) reactions, which will be studied at the Radioactive Ion Beam Line in Lanzhou, China. This detector will provide on a particle-by-particle basis tracking information and arrival time of radioactive beams with intensities up to 105 particles per second. The key requirements of the experiments to the detector are that the spatial resolution is below 1 mm, the time resolution is better than 1 ns and the energy loss is less than for a parallel plate avalanche counter. The current prototype is composed of two micro-channel plate detectors with a compact electrostatic field construction and a delay-line readout. Based on the results of α-particle tests, one micro-channel detector can achieve a position resolution of 552μm full width at half maximum on the x axis and 735μm on the y axis. The tracking system can achieve 705 ps time resolution and can cope with a beam intensity of up to 5 ×106 particles per second.

Experimental study of the elastic scattering of 10Be on 208Pb at the energy of around three times the Coulomb barrier * * Supported by the National Natural Science Foundation of China (U1632138, 11575256, 11605253, 11705242, 11875297)

Elastic scattering of 10Be on a 208Pb target was measured at = 127 MeV, which corresponds to three times the Coulomb barrier. The secondary 10Be beam was produced at the Radioactive Ion Beam Line in Lanzhou of the Heavy-Ion Research Facility in Lanzhou. The angular distribution of elastic scattering in the 10Be + 208Pb system shows a typical Fresnel diffraction peak. Optical model analysis of the angular distribution was performed using the Woods-Saxon, double-folding and global potentials. With the global potential, different density distributions were used. The results indicate that different density distributions for the projectile induce distinct effects in the angular distribution.

Silicon detector array for radioactive beam experiments at HIRFL-RIBLL

A new and innovative detector system based on a silicon strip detector dedicated to the study of the reaction induced by lighter radioactive beams is described herein. The detector system consists of five sets of three types of telescopes, which are successfully used to measure the angular distributions of both elastic scattering and breakup simultaneously, on the Radioactive Ion Beam Line in Lanzhou at Heavy Ion Research Facility in Lanzhou. This silicon detector array is used to measure the elastic scattering angular distributions of $$^{11}$$ Be on a $$^{208}$$ Pb target at $${E}_\mathrm{lab}=140$$ and 209 MeV. A comparison of the Monte Carlo simulations with the experimental results shows a reasonable consistency.

STUDY OF NEUTRON RADIATION FIELD AT THE FIRST RADIOACTIVE ION BEAM LINE IN LANZHOU.

The first Radioactive Ion Beam Line in Lanzhou was a projectile fragment separator located in the HIRFL. The process of production and separation of radioactive ion beams can induce a strong and complex radiation field. The neutron dose equivalent rates were measured in four positions with a 70 MeV/u 40Ar18+ beam. The results were compared with that simulated by the FLUKA code. New shielding walls were installed to reduce the neutron background for spectroscopy measurement in the experimental terminal. In addition, the induced radioactivity of accelerator components and corresponding residual dose rates were analyzed for the radiation safety of accelerator workers. The airborne radioactivity as well as occupational exposure due to immersion in and inhalation of activated air were also estimated. This work aims to provide a valuable experience for the radiation study in the future fragment separator HFRS at HIAF.

$\beta$ β -delayed particle emission from 21Mg

The -delayed particle emission from 21 Mg was studied at the Radioactive Ion Beam Line in Lanzhou (RIBLL1). Silicon array and high-purity germanium (HPGe) detectors were used to detect the charged particles and -rays emitted from the decay. Half-life time of 21 Mg was determined to be 121.9(6) ms. New levels (5.639(26) MeV and 6.644(34) MeV) in the nucleus 21 Na were observed. An improved proton spectrum coincident with -rays at 1.633 MeV was obtained. A new partial decay scheme was constructed based on the present measurement.

Experimental study of the $$^{9}\hbox {Li}$$ 9 Li breakup reaction on Pb target

The breakup reaction of $$^{9}\hbox {Li}$$ on a Pb target has been measured at 32.7 MeV/nucleon for the first time. Two peaks of $$^{6}\hbox {He}+\hbox {t}$$ coincident fragments at 9.8 and 12.5 MeV were observed and agreed with the results of the generator coordinate method calculation. The experiment was carried out thanks to a specially arranged detection system around zero degrees at the Heavy Ion Research Facility in Lanzhou, Radioactive Ion Beam Line in Lanzhou (HIRFL–RIBLL).

A detector setup for the measurement of angular distribution of heavy-ion elastic scattering with low energy on RIBLL

A detector setup for the measurement of angular distribution of heavy-ion elastic scattering at energies around Coulomb barrier on the radioactive ion beam line in Lanzhou at the heavy-ion research facility in Lanzhou is designed. The beam profile and the scattering angles on the target are deduced by two parallel plate avalanche counters, and four sets of detector telescopes (including double-sided silicon strip detectors) are placed systematically with the beam line, incorporating with Monte Carlo simulations. The data of $$^{16}\hbox {O}$$ on $$^{89}\hbox {Y}$$ target were analyzed to compare with the simulation results. It is found that the simulated distribution is agreeable with the experimental data. By assuming the pure Rutherford scattering at small scattering angles, the angular distribution of elastic scattering of $${}^{16}\hbox {O} + {}^{89}\hbox {Y}$$ at low energies can be reasonably obtained. It indicates that this set of detector setup can be used for the measurement of angular distributions of heavy-ion elastic scattering at energies around Coulomb barrier.

The calibration of elastic scattering angular distribution at low energies on HIRFL-RIBLL

The precise calibration of angular distribution of heavy-ion elastic scattering induced by Radioactive Ion Beams (RIBs) at energies around Coulomb barrier on the Radioactive Ion Beam Line in Lanzhou (RIBLL) at the Heavy-Ion Research Facility in Lanzhou (HIRFL) is presented. The beam profile and the scattering angles on the target are deduced by a measurement with two Multi Wire Proportional Chambers (MWPC), and four sets of detector telescopes (including Double-sided Silicon Strip Detectors (DSSD) placed systematically along the beam line, incorporating with Monte Carlo simulation. The MWPCs were used to determine the beam trajectory before the target, and the energies and the positions of scattered particles on the detectors were measured by the DSSDs. Minor corrections on the beam spot and the detector position are performed by assuming the pure Rutherford scattering at angles which are smaller than the related grazing angle. This method is applied for the elastic scattering of 17F on 89Y target at Elab=59MeV and 50MeV.

Detector system for the angular distribution measurement of 12C + 12C elastic scattering at 200–400A MeV

To obtain the angular distributions of 12C + 12C elastic scatterings with the incident energies of 200–400AMeV for the study of three-body forces, a detector system was constructed at second Radioactive Ion Beam Line in Lanzhou (RIBLL2) of Institute of Modern Physics (IMP). This system was composed of five plastic scintillation detectors with two read-outs for each detector, a Multi Wire Proportional Chamber (MWPC) and a 4×4 CsI(Tl) array. The 12C beam with the incident energy of 200AMeV on a natural carbon target was used to test this detector system. It is found that the plastic scintillation detector can give the good energy loss (ΔE) and time of flight (TOF) signals, it can also reflect the position information of scattered 12C events. MWPC can precisely provide the trajectories of scattered particles. This system has a very good particle identification ability and can clearly distinguish the scattered 12C particles from the fragments. It can be used for the study of the three-body forces effect for high energy heavy-ion scattering.

A detection system for charged-particle decay studies with a continuous-implantation method

A new detection system with high detection efficiency and low detection threshold has been developed for charged-particle decay studies, including β-delayed proton, α decay or direct proton emission from proton-rich nuclei. The performance was evaluated by using the β-delayed proton emitter 24Si produced by projectile fragmentation at the First Radioactive Ion Beam Line in Lanzhou. Under a continuous-beam mode, the isotopes of interest were implanted into two double-sided silicon strip detectors, where the subsequent decays were measured and correlated to the preceding implantations by using position and time information. The system allows us to measure protons with energies down to about 200keV without obvious β background in the proton spectrum. Further application of the detection system can be extended to the measurements of β-delayed proton decay and the direct proton emission of more exotic proton-rich nuclei.

Particle tracking simulation in the CSRe stochastic cooling system**Supported by Innovation Community of National Fund Committee (11221064) and National Key Basic Research and Development Project (2014CB845500)

A stochastic cooling system is under design and construction at HIRFL-CSRe (Heavy Ion Research Facility in Lanzhou - experimental Cooling Storage Ring), with the aim of cooling secondary particles produced at HIRFL-RIBLL2 (2nd Radioactive Ion Beam Line in Lanzhou). The optical layout of CSRe has been optimized to meet the requirements of a stochastic cooling system. In this paper, a particle tracking method is used to investigate both transverse and longitudinal cooling on the basis of the modified optical layout, demonstrating how it can be used to optimize stochastic cooling parameters. Simulation results indicate that the particle tracking method is an innovative and reasonable method to study stochastic cooling. It also has the advantage of discovering the influence of Twiss parameters at the pickups and kickers, which will be explored in further studies.

Experimental Study of Beta-Delayed Proton Emission of 36,37Ca

The investigation of beta-delayed proton decay mode has become a powerful probe to study the proton-rich nuclei and their nuclear structure. To study exotic nuclei with extremely low purity produced by the Radioactive Ion Beam Line in Lanzhou, we perform an experiment of beta-delayed proton emission of 36,37Ca under a high-intensity continuous-beam mode. Ions are implanted into a double-sided silicon strip detector, where the subsequent decays are correlated to the preceding implantations in time sequence. The energy spectra of delayed protons from 36,37Caβ decay, half-lives and decay branching ratios are measured. The experimental results confirm the previous literature data and some improved results are obtained as well, demonstrating the feasibility of our detection approach and the reliability of our data analysis procedure. This allows for the development of more powerful detection arrays and further research on nuclei closer to proton-drip line on the basis of present work.

Quasi-elastic scattering ofC10,11andB10from aPbnattarget

Angular distributions of the differential cross sections for the quasi-elastic scattering from a $^{\mathrm{nat}}\mathrm{Pb}$ target by $^{10}\mathrm{C}$ at 226 and 256 MeV, by $^{11}\mathrm{C}$ at 222 MeV and 226 MeV, and by $^{10}\mathrm{B}$ at 173 MeV were measured at the Heavy Ion Research Facility in Lanzhou, Radioactive Ion Beam Line in Lanzhou (HIRFL-RIBLL). Contributions from the inelastic scattering channels to these data are found to be negligibly small with coupled-channel calculations within the angular range covered by this experiment. These data can be well reproduced by optical model calculations with systematic nucleus-nucleus potentials. The reduced total reaction cross sections were compared with other existing data.

A method for the measurement of elastic scattering angular distribution at HIRFL-RIBLL

A method is presented for the measurement of differential cross-sections of heavy ion elastic scattering induced by Radioactive Ion Beams (RIBs) on the Radioactive Ion Beam Line in Lanzhou (RIBLL) at the Heavy-Ion Research Facility in Lanzhou (HIRFL). The disadvantages of broad beam profiles and limited intensities of the RIBs were overcome using large area detectors, two Parallel-Plate Avalanche Counters (PPACs), two double-sided silicon strip detector (DSSD) telescopes, incorporated with Monte Carlo simulations. The PPACs were used to determine the direction and position of the beam particles. The DSSD telescopes were used to measure scattered particles. Small corrections for the misalignment of detectors and the data normalization were made by assuming the pure Rutherford scattering at very forward angles. The method is suitable for the measurement of the cross-sections on heavy targets at low and intermediate energies, and it has been successfully applied to measure the angular distribution of elastic scattering of 7Be on Pb target at Elab=17.9MeV/u.

A new low-energy radioactive beam line for nuclear astrophysics studies in China

A gas-target system has been newly developed and installed at a Radioactive Ion Beam Line in Lanzhou (RIBLL), which makes RIBLL capable of delivering intense, low-energy RIBs for nuclear astrophysics studies. A 1.7×104-pps intensity 22Na RI beam has been achieved in a commissioning run. With further improvements, a 105-pps intensity of some RI beams with mass A<30 (close to the line of β-stability) can be expected in the near future. Some detection equipment including Germanium and Silicon arrays (or balls) available (or to be constructed) at IMP are briefly introduced. A new low-energy radioactive beam line in China is now ready for nuclear astrophysics studies.

Projectile fragmentation reactions of40Ar at 57 MeV/nucleon

The projectile fragmentation reactions of ${}^{40}$Ar at 57 MeV/nucleon on ${}^{9}$Be and ${}^{181}$Ta targets have been studied by the Radioactive Ion Beam Line in Lanzhou (RIBLL) at the Heavy-Ion Research Facility in Lanzhou (HIRFL). The momentum distributions of fragments have been measured and the competition between different mechanisms are observed. The production cross sections have been obtained and compared with the empirical parametrization of fragmentation cross section (EPAX), abrasion-ablation (AA), and heavy-ion phase space exploration (HIPSE) models, and the target dependence of fragment cross sections has also been discussed.