Subjects: Physics >> Nuclear Physics submitted time 2024-05-23
wang ruoxu
Yuan He
shi longbo
Li chenxing
xue zongheng
jiang tiancai
xu xianbo
sun liepeng
zhang zhouli
Abstract： To verify the rationality of the design of the power coupler for the RFQ cavity and to reduce contamination of the cavity, the low loss offline conditioning cavity was designed and high power test was conducted. The offline cavity was composed of two coupling ports and two tuners. Furthermore, the loss of the cavity could be minimized by the installation angle of the coupling ring and the insertion depth of the tuner. Electromagnetic structural and multiphysics simulations of the cavity were conducted, and the minimal theoretical power loss of the cavity was 4.3%. When the frequency variation of cavity was 110kHz, the theoretical power losses increased to 10%. Therefore, the tuner was always in motion during conditioning. Multiphysics simulations showed that the increased temperature of the cavity did not affect the frequency variation. When the offline high power conditioning platform was completed, the transmission performance of the conditioning system was measured. The power loss was 6.3%, larger than the theoretical calculation value. The conditioning employed efficient automatic range scanning and standing wave resonant conditioning methods. In order to fully condition the power coupler, 13 standing wave points were selected. The maximum continuous wave power is greater than 20kW, better than the expected target.
Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics submitted time 2024-05-21
Abstract： The cooling storage ring (CSR) external-target experiment (CEE) is a spectrometer used in construction to study the properties of nuclear matter in high-baryon density regions at the Heavy-Ion Research Facility in Lanzhou (HIRFL). This study presents the design, simulation, manufacturing, and testing of a half-size prototype of a multi-wire drift chamber (MWDC) for the CEE. First, the performance of the MWDC connected to home-made electronics was simulated. The results demonstrated that an energy resolution of 18.5% for 5.9-keV X-rays and a position resolution of 194 um for protons can be achieved by the current design. Because the size of the largest MWDC reached 176 × 314 cm, a set of 98 × 98 cm prototypes was built using the new techniques. The positioning accuracy of the anode wires in this prototype exceeded 20 um. After optimization using commercially available electronic devices, the prototype achieved an energy resolution of 19.7% for a 55Fe X-ray source. The CEE-MWDC detector and electronics were simultaneously tested. An energy resolution of 22% was achieved for the 55Fe source; the track residuals were approximately 330 um for the cosmic rays. The results demonstrate that the current design and techniques meet the requirements of the CEE-MWDC array.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-04
Abstract： 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.
Peer Review Status:
Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2024-01-04
Abstract： 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.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2023-11-06
Yang, Mingyu
Qian, Yi
Pu, Tianlei
Lu, Weijian
Sun, Zhikun
Zhao, Hongyun
Zhang, Jiarui
Liu, Zhengqiang
Abstract： HFRS (HIAF FRagment separator) will be the radioactive secondary beam separation line on High-Intensity heavy-ion Accelerator Facility (HIAF) in China. Several TPC detectors, with high count rates, are planned for particle identification and beam monitoring at HFRS. This paper presents an event-driven internal memory and synchronous readout (EDIMS) prototype ASIC chip. The aim is to provide HFRS-TPC with high-precision time and charge measurements with high count rates and a large dynamic range. The first prototype EDIMS chip integrated 16 channels and is fabricated using a 0.18-µm CMOS process. Each channel consists of a charge-sensitive amplifier, fast shaper, slow shaper, peak detect-and-hold circuit, discriminator with time-walk compensation, analog memory, and FIFO. The token ring is used for clock-synchronous readout. The chip is taped and tested.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-06-06
Abstract： In this study, a phenomenological model of the radio frequency (RF) behavior of a superconducting cavity fundamental power coupler is proposed by analyzing the simulation results of a transient beam loading process in an extremely over-coupled superconducting cavity. Using this phenomenological model, the calculation of the transient reflected power from a superconducting cavity under beam loading can be mathematically simplified to algebraic operations without solving the differential equation governing the transient beam loading process, while maintaining the calculation accuracy. Moreover, this phenomenological model can facilitate an intuitive understanding of the significant surge in the time evolution of reflected power from a superconducting cavity in certain beam-loading processes. The validity of this phenomenological model was carefully examined in various beam loading processes and cavity conditions, and the method based on this phenomenological model was utilized in the transient RF analysis of the superconducting cavity system of the CAFe Linac, achieving satisfactory results.
Subjects: Physics >> Nuclear Physics submitted time 2023-06-06
Abstract： β-decay half-life and the β-delayed neutron emission (βn) are of great importance in the development of basic science and industrial applications, such as nuclear physics and nuclear energy, where β−-decay plays an important role. Many theoretical models have been proposed to describe β-decay half-life, while the systematic study on βn is still rare. This paper aims to investigate β−-decay half-lives and βn probabilities through analytical formulas and compare them with the experimental data. Analytical formulas of the β−-decay properties have been proposed in considering the prominent factors: decay energy, odevity, and shell effect. The bootstrap method is used to simultaneously evaluate the total uncertainty of calculations, composed of the statistic and systematic uncertainties. The β−-decay half-lives, βn probabilities, and the corresponding uncertainties have been evaluated for the neutron-rich region. The experimental half-lives are well reproduced. More predictions are also presented with theoretical uncertainties, which helps better understand the disparity between experimental and theoretical results.
Subjects: Physics >> Nuclear Physics submitted time 2023-05-31
Abstract： A simulation code, GOAT, is developed to simulate single-bunch intensity-dependent effects and their interplay in the proton ring (pRing) of the Electron-Ion Collider in China (EicC) project. GOAT is a scalable and portable macroparticle tracking code written in Python and coded by object-oriented programming technology. It allows for transverse and longitudinal tracking, including impedance, space charge effect, electron cloud effect, and beam-beam interaction. In this paper, physical models and numerical approaches for the four types of high-intensity effects, together with the benchmark results obtained through other simulation codes or theories, are presented and discussed. In addition, a numerical application of the cross-talk simulation between the beam-beam interaction and transverse impedance is shown, and a dipole instability is observed below the respective instability threshold. Different mitigation measures implemented in the code are used to suppress the instability. The flexibility, completeness, and advancement demonstrate that GOAT is a powerful tool for beam dynamics studies in the EicC project or other high-intensity accelerators.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2023-05-31
Abstract： Carbon-ion radiotherapy (CIRT) offers unique physical and biological advantages over photon radiotherapy. However, some
materials and devices in the CIRT treatment room become radioactive under bombardment by therapeutic carbon-ion beams
due to nuclear reactions, thereby leading to possible radiation hazards to medical staff and additional and unwanted doses
to patients. This study assessed the level of induced radioactivity in the treatment room of the Heavy-Ion Medical Machine
(HIMM) in Wuwei. Monte Carlo simulations using PHITS were performed for a conservative case under the conditions of
maximum beam energy and intensity provided by the HIMM facility. The geometry and configuration of Treatment Room
2 of the HIMM facility in Wuwei were adopted. We evaluated the activation of air, the phantom, and the components of
the beamline, such as the primary collimator (PC), ridge filter (RF), and multileaf collimator (MLC). For air activation,
we calculated the medical staff immersion external exposure and inhalation internal exposure caused by the corresponding
radionuclides. For phantom activation, we estimated the additional dose to the patient’s family members owing to secondary
photons after treatment. In addition, the exemption or non-exemption of the component material activation was assessed.
The results showed that external radiation caused by air activation was the main source of the annual effective dose at
approximately 0.5 mSv/y. The induced radioactivity exposure to family members of a patient after CIRT was approximately
40 μSv, sufficiently lower than the public dose limit of 1 mSv/a. The induced radioactivity of the PC, RF, and MLC was all
above the exempt levels after the devices were retired, whereas the induced radioactivity of the RS and compensator could
reach the exempt levels after one patient session. Our study indicated that medical staff engaged in CIRT should stay away
from the high-dose-rate area of induced radioactivity along the beam direction, shorten the residence time in the treatment
room as much as possible, and store the activated components in isolation after the equipment is out of use. Thus, this study
provides guidance for accurately assessing the level of induced radioactivity in the treatment room for CIRT.
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