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This study presents a comprehensive physics design and optimization investigation of an electron injector system for the Korea fourth-generation storage ring (Korea-4GSR) light source with a target operating energy of around 200 MeV. The Korea-4GSR construction project is currently underway and expected to continue until 2027. The injector system comprises a thermionic dc gun, buncher systems, and four accelerating cavities (ACs). The thermionic gun was designed to achieve a combination of low emittance and high current. Through beam dynamics simulations, we investigated different types of buncher and ACs. Optimization was performed on the geometries and electromagnetic properties of each cavity type to enhance beam bunching and acceleration. Nonlinear optimization techniques were employed to maximize transmission efficiency by adjusting solenoidal magnet strengths and minimize energy spread by optimizing RF input phases and cavity positions. Our results demonstrated a transmission efficiency of 98.71%, an rms energy spread of 0.54%, a bunch length of 4.11 ps, and an normalized rms transverse emittance of 3.2219 mm $\cdot $ mrad, meeting the design requirements of the Korea-4GSR injector system.

We examine the effect of the broadband wake on the longitudinal and transverse beam distributions in the low-emittance Hybrid Multi-bend Achromat (HMBA) storage ring. We utilize the Vlasov equation and a multi-particle tracking method to examine the equilibrium longitudinal beam distributions due to the broadband wake. The beam distributions from the Vlasov method is shown to agree well with the multi-particle tracking results. Multi-particle tracking simulations are also performed to investigate the longitudinal and transverse beam instabilities due to the broadband wake in the ring. In view of our results, our designed ring with Z/n=0.1Ωis shown to make the producion of a beams possible.

Hominis placental (HPP) extract has been approved by the Ministry of Food and Drug Safety in Korea for treating chronic liver diseases and postmenopausal syndrome. However, its efficacy and safety for treating chronic temporomandibular disorder (TMD) remains unclear. We aimed to assess the effectiveness and safety of HPP for treating chronic TMD compared with physical therapy (PT).

We investigate the generations of a high-flux γ-ray beams by laser Compton scattering. We performed the design of an energy recovery linac that produces a γ-ray beam with the flux of ∼ 1013photons/s. It is important to examine the effects on beam performances of the ERL in detail. Thus, we examined the effects of emittance growths on higher order modes in the superconducting linac and coherent synchrotron radiation in the designed lattice of the energy recovey linac. They were checked by performing the start-to-end simulation of multi-beam particle trackings in the designed 355 MeV ERL. It was shown that the energy recovery linacs by laser Compton scattering may provide monochromatic high-flux gamma-ray beams. It is shown through our design studies that goals of γ-ray beam parameters in the ERL facility are achievable. Such an energy-tunable γ-ray beams that are generated by laser Compton scattering may be applied to nuclear resonance fluorescence(NRF) measurements for the non-destructive detection of radioactive nuclear materials. The investigations show that our design studies provide a good optimized ERL parameters in terms of beam dynamics.

We show the design results of beam dynamics on the injector for high-intensity proton accelerators. The injector can be utilized in a medical proton linac and accelerator driven system. The injector system consists of a 325-MHz RFQ (radio-frequency quadrupole) accelerator and a 325-MHz DTL (drift tube linac) accelerator. The injector has been designed to optimize the beam parameters to meet the required design goals. In this paper, we present a design study on the beam dynamics in the injector through beam tracking. We show the results of the beam dynamics study and cavity design study in the RFQ. The high-intensity RFQ accelerates the proton beam from 50 keV to 3 MeV with a peak beam current of 30 mA. The RFQ has a length of 3.839 m and Kilpatrick value of 1.76. We investigated ways to minimize the emittance growth caused by the space-charge effect and optimized achieve a high transmission and a small growth of emittance along the RFQ. The DTL with face angles of 3 degree and 10 degree in one tank accelerates proton beams from 3 MeV to 10 MeV and is 4.3 m long. Electromagnet quadrupoles (EMQs) are used as focusing elements in a Focusing-Defocusing-Focusing-Defocusing (FFDD) lattice scheme in the DTL. A quadrupole between the RFQ and the DTL, and 8 drift tubes (DT) in DTL are used for transverse matching in the DTL. We investigated the beam dynamics to achieve a high transmission and a small growth of emittance along the DTL. We also show the results of beam tracking simulations in the DTL. Our studies show that major parameters affecting on beam dynamics in the injector for a high-intensity proton linac are available.

We have investigated designs for a superconducting single spoke resonator with a resonant frequency of 325 MHz and an optimum beta of 0.51. In this paper, we suggest a balloon variant of a spoke cavity having an end-wall structure, which has a distinct advantage from the viewpoint of multipacting suppression. We determined the geometric parameters of the balloon-shaped single spoke resonator through electromagnetic, multipacting, and mechanical simulations. In addition, we discuss the resonant frequency shifts caused by the cavity processing, the power coupling, and the cavity tuning.

The Rare Isotope Science Project (RISP) is a research complex consisting of a heavy-ion accelerator, which contains a front-end system, a super-conducting linear accelerator, an isotope separator online (ISOL) system, and an in-flight system. The original purpose of the post-linear-accelerator (post-linac) section was to accelerate either a stable driver beam derived from an electron cyclotron resonance ion source, or an unstable rare-isotope beam from an ISOL system. The post-linac lattice has now been redesigned using a novel and improved acceleration concept that allows the simultaneous acceleration of both a stable driver beam and a radioisotope beam. To achieve this, the post-linac lattice is set for a mass-to-charge ratio (A/q) that is the average of the two beams. The performance of this simultaneous two-beam acceleration is here assessed using two ion beams: $$^{58}{\mathbf{Ni}}^{8+}$$ 58Ni8+ and $$^{132}{} {\mathbf{Sn}}^{20+}$$ 132Sn20+ . A beam dynamics simulation was performed using the TRACK and TraceWin codes. The resultant beam dynamics for the new RISP post-linac lattice design are examined. We also estimate the effects of machine errors and their correction on the post-linac lattice.

In this paper, we present an echo-enabled harmonic generation (EEHG) scheme to generate a free electron laser (FEL). The EEHG FEL utilizes two modulators and two chicanes that can generate a high harmonic density modulation with a low initial beam energy modulation. Using the beam parameters of a 150-MeV electron accelerator, we show that the EEHG scheme enhances FEL performance and generates coherent radiation with a wavelength of 100 nm. In this scheme, the 150-MeV electron beam is energy-modulated by using two lasers with wavelengths of 800 and 2400 nm. The modulated electron beam is sent to two chicanes whose dispersive strengths are 8.2 and 1.0 mm to convert energy modulation to density modulation. Finally, the density-modulated electron beam is sent to a radiator that is tuned to a wavelength of 100 nm and generates radiation with a peak power of 0.3 GW. We performed simulations of the laser-beam interaction by using the GENESIS code and showed that intense coherent radiation with a wavelength of 100 nm could be achieved from the two seeding lasers under the designed EEHG scheme.

The Korea Heavy Ion Medical Accelerator consists of an injector and a synchrotron for an ion medical accelerator that is the first carbon-ion therapy system in Korea. The medium energy beam transport(MEBT) line connects the interdigital H-mode drift tube linac and the synchrotron. We investigated the beam conditions after the charge stripper by using the LISE++ and the SRIM codes. The beam was stripped from C4+into C6+by using the charge stripper. We investigated the performance of a de-buncher in optimizing the energy spread and the beam distribution in z-dW/W (direction of beam progress-beam and energy) phase. We obtained the results of the tracking simulation and the error analysis by using the TRACK code. Possible misalignments and rotations of the magnets were considered in the simulations. States of the beam were examined when errors occurred in the magnets by the applying analytic fringe field model in TRACK code. The condition for the beam orbit was optimized by using correctors and profile monitors to correct the orbit. In this paper, we focus on the beam dynamics and the error studies dedicated to the MEBT beam line and show the optimized beam parameters for the MEBT.

We investigated the effects of magnet errors in the beam transport line connecting the post linac to the driver linac (P2DT) in the Rare Isotope Accelerator in Korea (RAON). The P2DT beam line is bent by 180-degree to send the radioactive Isotope Separation On-line (ISOL) beams accelerated in Linac-3 to Linac-2. This beam line transports beams with multi-charge state 132Sn45,46,47. The P2DT beam line includes 42 quadrupole, 4 dipole and 10 sextupole magnets. We evaluate the effects of errors on the trajectory of the beam by using the TRACK code, which includes the translational and the rotational errors of the quadrupole, dipole and sextupole magnets in the beam line. The purpose of this error analysis is to reduce the rate of beam loss in the P2DT beam line. The distorted beam trajectories can be corrected by using six correctors and seven monitors.

The multi-bend achromat (MBA) lattice, which can provide a small horizontal emittance in the subnanometer range, shows promise for future storage-ring-based light-source facilities. We present the linear and the nonlinear properties of an optical design and the results of its optimization. The MBA lattice is designed as a five-bend achromat, and an emittance of 0.270 nm rad is achieved. The energy and the circumference of the designed ring are 3 GeV and 499.3 m, respectively. We investigated an injection system with a single-pulsed sextupole magnet in the storage ring. We describe the space allocation in the injection section and the particle dynamics of the injected beam. The investigation shows that our design exhibits a very low emittance and a sufficient dynamic aperture, and provides a suitable injection scheme for a 3-GeV light source.

X-ray generation based on laser-electron Compton scattering is a method to generate a compact high-flux X-ray source. At the Pohang Accelerator Laboratory’s (PAL’s) fs-THz facility, 3-THz radiation has been achieved using an electron beam of 150 fs rms. To further enhance the radiation bandwidth, we present design results on X-ray generation by using Compton scattering at the facility. We show the design performance for the Compton source by using a 75-MeV electron linac with a 800-nm laser system. The Compton scattering X-ray source will be a compact facility that produces 3.1 × 107photons in a single shot and a maximum photon energy of 130 keV. In this paper, we show the system layout and the design parameters that offers an ultra-short, high-flux hard X-ray source. We present the simulation studies to optimize the parameters of the electron beam and the X-ray pulse that was given by code CAIN.

The Korea Atomic Energy Research Institute (KAERI) has used a microtron accelerator based on a thermionic cathode for operating a compact terahertz (THz) FEL, where the electrons are emitted and accelerated automatically during the radio-frequency (RF) macro-pulse over threshold power for their emission. Usually a thermionic cathode is embedded inside the microtron cavity for electron-beam emission, and at the same time acceleration is due to the input RF source. In this case, the accelerator scheme is simple, but just a fraction of the emitted electrons are accelerated, and the electron bunch length is uncontrollable due to the RF phase condition for acceleration. In this paper, a photocathode-based microtron which is able to produce high peak (∼100 A) and ultrashort (∼1 ps) electron bunch is studied to adapt it for an electron injector of a THz generator. Especially, we analyzed the electron beam dynamics along the accelerating trajectory with a 3D PIC-code to find the optimized RF phase and laser input time.

The low-energy beam-transport (LEBT) line for the post accelerator is required to deliver effectively the beam produced by the electron-cyclotron resonance ion source (ECR-IS). This LEBT was designed and optimized to transmit a 58Ni8+ion beam with an energy of 5 keV/u at the entrance of the LEBT. This line consisted of a 90-degree dipole, a pair of solenoids, electrostatic quadrupoles and a multi-harmonic buncher. The designed LEBT showed a root-mean-squared (RMS) envelope and total length of less than 14 mm and 7 meters, respectively. This paper presents the results for the optics design and the beam tracking that were obtained by using TraceWin and TRACK codes.

The front-end system of rare isotope accelerator of newness (RAON) heavy-ion accelerator, which consists of an electron cyclotron resonance (ECR) ion source, a low energy beam transport (LEBT), a radio frequency quadrupole (RFQ) and a medium energy beam transport(MEBT), is now in the technical design phase to optimize and improve the optics. Especially, MEBT system is installed between the RFQ linac and the superconducting linac (SCL). It requires careful matching of the optical parameters in transverse plane and removes the unaccelerated ion beams from the RFQ linac. It also includes the beam diagnostic devices to measure the beam quality at the exit of the RFQ linac. Quadrupole magnets and normal-conducting re-bunchers are used to minimize the growths of the transverse and the longitudinal emittances. To remove the unaccelerated ion beams, we choose a normal-conducting quarter wave resonator (QWR) and designed it by using the Micro Wave Studio (MWS) code. The re-buncher has a maximum electric field of 2.95 MV/m on the cavity surface with an electric field of 1 MV/m on the beam axis, a geometrical beta factor of 0.025 and an effective length of 22 cm. Beam simulations shows that the beams from upstream of the LEBT and the RFQ can be transported by the MEBT without any increases in the beam emittances.

Abstract: We present a design for a non-scaling fixed-field alternating gradient accelerator (FFAG) for proton beams of 250 MeV. For this design, a radial sector type FFAG that has a triplet structure of focusing-defocusing-focusing magnets is investigated as a machine to provide the proton beam. We show the design results for the non-scaling FFAG and discuss the optimization of the lattice parameters in the accelerator. The FFAG accelerator is shown to provide a large transverse acceptance from the tracking beam in the designed lattice. The proton beams in the designed FFAG accelerator may be utilized for various purposes such as experiments in nuclear physics and medical applications.

Objective To determine whether pain is associated with gait instability in patients with lumbar disc herniation (LDH).Methods This retrospective cross-sectional study used data from electronic medical records. Among patients with lumbar back pain caused by LDH between January 2017 and July 2019, patients that underwent gait analysis were included. LDH was diagnosed using magnetic resonance imaging. An OptoGait photoelectric cell system was used for gait evaluation. Instability was measured using a gait symmetry index. Multivariate linear regression analysis was performed to determine the association between lumbar pain and gait instability.Results A total of 29 patients (12 females [41.4%] and 17 males [58.6%]; mean ± SD age, 40.6 ± 12.0 years) with LDH were enrolled in the study. With each 1-point increase in lumbar pain on the numeric rating scale, the symmetry index of the stance phase (0.33; 95% confidence interval [CI] 0.04, 0.62), swing phase (0.78; 95% CI 0.14, 1.43) and single support (0.79; 95% CI 0.15, 1.43) increased.Conclusions Gait instability in patients with LDH may occur due to an increase in pain.

One affiliation of Sunjeong Park was omitted. It should be added as “Department of Physics, Kyungpook National University, Daegu 702-701, Korea”. Affiliation of Eun-San Kim had a typo. It should be corrected as “Department of Physics, Kyungpook National University, Daegu 702-701, Korea”.

The effect of a beam-beam interaction on the motion of a circulating beam in a 50 GeV ×50 GeV muon-collider ring is investigated by weak-strong beam modeling. In the present design of the muon-collider storage ring, the frequency-slippage factor ?1is approximately -5×10-7so that the synchrotron motion is nearly frozen. This may lead to an increase in the energy spread due to the beam-beam interaction. Through the weak-strong beam modeling, we have investigated the parametric dependencies of the energy spread induced by the beam-beam interaction. We show in this paper that the energy spread due to the beam-beam interaction is large and can be compensated for by employing one rf cavity in the ring with a modest rf voltage.

The dynamic apertures in several lattices for the low emittance of the Photon Factory storage ring (PF ring) have been investigated by a simulation method using the code Strategic Accelerator Design (SAD). The dynamic apertures in each lattice without and with machine errors were obtained by a tune survey in the simulation. It was also shown how large are the dynamic apertures compensated after corrections of a closed orbit distortions. The operating tunes in low-emittance lattices can be obtained based on the view point of dynamic apertures obtained from a tune survey. It is shown that a low-emittance 90° cell lattice provides sufficient dynamic aperture after a correction of the closed orbit distortion in the PF ring.