Design of a Proton Beamline Specialized for Radiation Testing of Semiconductors at KOMAC

Design of a Proton Beamline Specialized for Radiation Testing of Semiconductors at KOMAC | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Design of a Proton Beamline Specialized for Radiation Testing of Semiconductors at KOMAC Han-Sung Kim, Seung-Hyun Lee, Sang-Pil Yun, Dong-Hwan Kim, Hyeok-Jung Kwon This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8686527/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract The demand for radiation hardness testing of semiconductor devices has been rapidly increasing, particularly for space and high-reliability applications. To address this need, a dedicated proton beamline for semiconductor radiation testing is being developed at the Korea Multi-purpose Accelerator Complex (KOMAC) using an existing 100 MeV proton accelerator. The beamline is designed to deliver a large-area, low-flux proton beam suitable for displacement damage and single event effect tests. The beamline incorporates a graphite-based water-cooled collimator to reduce the beam intensity and a magnet optics system consisting of quadrupole and octupole magnets to generate a wide and uniform flat-top beam profile. Beam dynamics simulations were performed to evaluate different optics configurations under the geometrical constraints of the penetration pipe. The simulation results demonstrate that a beam size of 100 mm × 100 mm with a uniformity better than ± 10% can be achieved. The collimator was designed to withstand an average beam power of up to 800 W, and coupled thermal–structural analyses confirmed that both temperature rise and thermal stresses remain within safe limits. Radiation shielding analyses further verified that the resulting dose rates satisfy radiation safety requirements. In addition, two octupole electromagnets were designed, fabricated, and experimentally characterized, showing good agreement between measured and simulated magnetic field properties. A dedicated target room was also designed to support efficient semiconductor irradiation experiments, featuring real-time beam diagnostics, redundant beam on-and-off control, and an integrated control interface with the accelerator system. The proposed beamline is expected to significantly enhance proton irradiation capabilities at KOMAC and provide an effective testing platform for the semiconductor industry and related research fields. KOMAC Beamline Radiation test Semiconductor Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 1. INTRODUCTION The assessment of semiconductor characteristics in response to radiation is a critical function performed at many proton beam facilities. The National Aeronautics and Space Administration (NASA) conducts radiation tolerance tests for space and aviation components [ 1 ], similar to efforts by the European Space Agency (ESA) and Japan Aerospace Exploration Agency (JAXA) [ 2 ]. These organizations operate independently or collaboratively utilize global facilities to perform these essential tests. The Korea Multipurpose Accelerator Complex (KOMAC) has been operating a low-flux beamline for radiation testing of semiconductors, which is accredited for JESD89B standard testing [ 3 ]. Despite this, the existing shared use of the beamline limits its availability to domestic users and users from other application fields. At KOMAC, a new beamline is planned to be built for radiation hardness testing of semiconductors. In this paper, we present a design study and development status of a beamline specialized for semiconductor radiation hardness testing at KOMAC. 2. BEAMLINE DESIGN The new beamline for semiconductor radiation hardness testing connects to TR104 on one of the 100 MeV beamlines, as shown in Fig. 1 . This beamline will feature a collimator, beam optics to create uniform beam profiles, and various beam diagnostics. A collimator will be installed to reduce the beam flux to 1/10,000. A graphite collimator with a 10 mm diameter aperture will significantly reduce the beam intensity, with most of the beam power being dissipated in the collimator. Additionally, a set of two octupole magnets and a quadrupole magnet will be installed to transform a Gaussian beam profile into a flat-top profile. Beam diagnostics such as an AC Current Transformer (ACCT), a stripline-type Beam Position Monitor (BPM), and a Faraday cup will be installed along the beamline. Furthermore, a 2D array ionization chamber will be installed at the target position to measure the transverse beam profile. In this section, we present the design specifications and simulation results that meet our design goals. 2.1 Design Specifications We aim to produce a beam of 100 mm × 100 mm with uniformity better than ± 10%. The design specifications are summarized in Table 1 . After passing through the collimator in the new beamline and broadening into a flat beam profile, the beam intensity can be as low as 10 5 protons/cm 2 per pulse. Table 1 Key design specification of the new beamline for semiconductor radiation hardness testing at KOMAC Parameter Design value Beam Energy at target 33 ~ 100 MeV Max. average power at collimator 800 W Max. average beam current at target 10 nA Beam size at target 100 mm × 100 mm Beam uniformity at target ± 10% The diameter of the penetration pipe between the beamline and the target room is 180 mm. To satisfy the design specifications given in Table 1 with the narrower penetration pipe compared to the low-flux beamline (i.e. the beamline to TR102 [ 4 – 7 ]), we have re-positioned the beam optics. 2.2 Beam Dynamics Analysis The beam dynamics simulation was performed from the collimator to the target position in TR104. Input beam parameter used in the simulation is given in Table 2 . The beam profile should be spread as much as possible while passing through the penetration pipe, with minimal beam loss. Two designs are considered for the beamline optics: 1) an octupole-quadrupole-octupole magnet configuration, and 2) a quadrupole-quadrupole-octupole-octupole magnet configuration. The first design (Design 1) is similar to the configuration used in the low-flux beamline to TR102. By adjusting the positions of the octupole-quadrupole-octupole magnets towards the end of the beamline and fine-tuning the distances between them, the beam size and uniformity are maximized, even with a smaller diameter penetration pipe. The results of Design 1 are shown in Fig. 2 . Particle and envelope calculations are performed using TraceWin code [ 8 ]. Table 2 Input beam parameter used in the simulation Beam Parameter x, y rms norm. emittance 0.225 π mm mrad α 0 β 13.3 mm/π mrad In Design 2, an additional quadrupole magnet is used to achieve a flat-top distribution in both the x and y directions. The results of Design 2 are shown in Fig. 3 . Design 1 can provide a significantly larger beam area while satisfying the beam uniformity within ± 10%; however, it results in higher beam loss compared to Design 2. Although Design 2 exhibits much lower beam loss, it is anticipated that optics adjustments will be challenging to achieve an increased flat beam area. 3. MAJOR COMPONENTS DEVELOPMENT 3.1 Water-cooled Collimator The beamline collimator was designed to shape the proton beam intensity to meet the requirements of a dedicated beamline for radiation testing of semiconductor devices (Fig. 4 ). Its primary function is to reduce the peak beam current while maintaining stable beam conditions suitable for irradiation experiments. Considering a thermal load of 800 W and radiation-induced activation, the collimator was fabricated using three materials: graphite, copper, and SUS316L stainless steel. A coupled thermal–structural analysis was performed to evaluate the temperature rise due to beam-induced heating, the resulting thermal stresses, and the mechanical stability of the interfaces between dissimilar materials with different coefficients of thermal expansion. The thermal analysis was conducted assuming a Gaussian round beam with a standard deviation of σ of 15 mm and a total beam power of 800 W. The beam was vertically offset by 40 mm from the beamline center in order to utilize the beam edge and thereby reduce the beam flux to approximately 0.1%. Water cooling was applied with a flow velocity of 2.5 m/s at an inlet temperature of 27°C through circular cooling channels with a diameter of 10 mm, corresponding to a convective heat transfer coefficient of 10,646 W/m²·K. The analysis results showed that the maximum temperature of the entire collimator was 100.41°C, which occurred in the graphite part. The maximum temperatures of the copper and SUS316L parts were 32.56°C and 30.93°C, respectively. The temperature increases in all components were well below the melting or sublimation temperatures of the respective materials. In addition, the temperature rise in the cooling channel region of the copper part remained below the boiling point of water. Therefore, the thermal load induced by the proton beam was judged to be within a safe operating range. Based on the temperature distribution obtained from the thermal analysis, a coupled structural analysis was performed. All contact interfaces between different components were assumed to be perfectly bonded. The maximum von Mises stresses were evaluated as 1.61 MPa for the graphite part, 27.45 MPa for the copper part, and 71.26 MPa for the SUS316L part. At the material interfaces, the maximum von Mises stresses were 6.62 MPa at the graphite–copper interface and 28.37 MPa at the copper–SUS316L interface. All evaluated stresses were below the yield strengths of the corresponding materials, indicating that the thermal stresses induced by beam heating are within safe limits. The beamline collimator consists of three main components: a graphite beam absorber, an oxygen-free copper (OFC) cooling jacket, and a SUS316L stainless steel collimator housing. The graphite beam absorber was machined using a multi-axis machining tool, including the fabrication of a 10 mm diameter hole. The cooling jacket and housing were assembled through a brazing process between the oxygen-free copper and stainless-steel components. Since a high vacuum is maintained inside the collimator, helium leak tests were performed on the cooling channels, yielding a leak rate of 1.0 × 10⁻⁹ Torr·L/s. During final assembly, the graphite beam absorber was pressed against the copper cooling jacket using twelve bolts to enhance the thermal contact between the components. Helium leak tests were again conducted after assembly to verify vacuum tightness. Figure 5 shows the fabricated beamline collimator. A shielding analysis was performed to evaluate the attenuation of neutrons and gamma rays generated when an 800 nA proton beam impinges on the collimator. The dose rates were assessed at locations accessible to personnel, including the corridor-side wall and the exterior wall of the facility. The shielding geometry used in the radiation transport calculations is shown in Fig. 6 . The calculated maximum dose rate was 8.49 µSv/h (relative error 1.77%) on the corridor side and 0.144 µSv/h (relative error 9.88%) on the exterior side of the building, indicating that the shielding design satisfies radiation safety requirements. 3.2 Octupole Magnet for Beam Expansion The octupole electromagnets generate higher-order multipole magnetic fields and are generally employed to suppress beam halo and correct nonlinear beam aberrations. Owing to the cubic dependence of the magnetic force on the distance from the magnet center, two identical octupole magnets were designed and fabricated to flatten both horizontal and vertical transverse beam profiles in a dedicated beamline for radiation testing of semiconductor devices. The octupole magnet was designed to satisfy the required pole field, third-order field gradient, and effective magnetic field length. The yoke has a regular octagonal shape with a longitudinal length of 226 mm and chamfered corners to reduce fringe fields. Semicircular pole tips with a radius of 20 mm form a bore diameter of 110 mm. The excitation coils were wound in a stepped configuration with 88 turns per pole. Three-dimensional magnetostatic simulations were performed using CST Studio Suite. The calculated magnetic flux density distribution at the longitudinal center of the magnet shows a clear null point at the center and a rapid increase in field strength with radial distance, consistent with an ideal octupole field (Fig. 7 ). The magnetic field distributions were further examined at multiple longitudinal positions, as shown in Fig. 8 . Circular symmetry was well preserved within the effective field region, while a residual fringe field of approximately 0.05 T was observed near the pole tips just outside the effective field boundary. Under a maximum operating current of 30 A, the magnet achieved a pole field of 0.12 T, a third-order field gradient of 8,539 T/m³, and an effective magnetic field length of approximately 226 mm without magnetic saturation. Two octupole electromagnet assemblies were fabricated, including cooling, mechanical alignment, and electrical systems (Fig. 9 ). Dimensional inspection and electrical and cooling tests confirmed that the fabricated magnets satisfied the design specifications. Magnetic field measurements were conducted at a coil current of 29.5 A. The measurement results of are summarized in Fig. 10 and Fig. 11 . The measured third-order field gradients were 8,316 T/m³ and 8,330 T/m³ for magnets #1 and #2, respectively, which differ by less than 1% from the simulated value. The measured effective magnetic field lengths ranged from 216 to 225 mm. These results confirm that the fabricated octupole electromagnets meet the performance requirements for transverse beam profile control in the radiation-test beamline. After completing all operational and magnetic field tests, the principal specifications and performance parameters of the fabricated octupole electromagnets are summarized as follows: Total excitation: 2,640 A·turns/pole (maximum 4,350 A·turns/pole) Pole field: ~0.231 T (maximum 0.341 T) Third-order field gradient (K₃): ~8,330 T/m³ (maximum 12,296 T/m³) Effective magnetic field length: ~223 mm (maximum 227 mm) Power consumption: 30 A, 13.9 V (maximum current 49.4 A) Cooling water flow rate: 5.16 L/h per coil (maximum 14 L/h per coil) Pressure drop: 2.2 bar (ΔT = 20°C), maximum 3 bar Weight: ~275 kg 3.3 Target Room for Semiconductor Testing A dedicated radiation test target room based on a 100 MeV proton accelerator was designed to support radiation effects testing of semiconductor devices, including displacement damage and single event effect (SEE) tests. The configuration and layout of the proton beam irradiation target room were determined with reference to the existing TR102 beamline. The target room is optimized to meet the key requirements for proton-beam-based soft error testing of semiconductor devices. The principal design parameters are as follows: proton beam energy of 20–100 MeV, beam fluence ranging from 1 × 10⁵ to 1 × 10⁹ cm⁻², a typical beam size of 100 mm × 100 mm, beam uniformity within ± 10%, and an external beam irradiation mode. The irradiation target room has dimensions of 4 m × 4 m × 3 m (width × length × height). To satisfy these requirements, the target room includes a beam window, beam shutter, defining and test collimators, transmission and monitoring ionization chambers, a range modulator (ridge filter), an energy degrader, a beam dump, a device-under-test (DUT) support structure with a universal sample holder, and a radiation monitoring system (RMS), as shown in Fig. 12 . To prevent malfunction caused by secondary radiation during irradiation, pneumatic cylinders were adopted for motion control instead of electric motors. In addition, low-activation materials such as graphite, engineering plastics, and aluminum alloys were preferentially used for all components to minimize radiation-induced activation and occupational exposure. To enhance operational efficiency and beam quality assurance, several key features were incorporated into the target room design. First, in-situ and real-time beam diagnostics were implemented to continuously monitor the beam profile, position, and intensity of the proton beam extracted through the beam window during irradiation. This capability enables operators in the control room to perform efficient beam tuning and significantly reduces beam preparation time, thereby increasing the effective beam time available to users. Second, a redundant beam on-and-off control scheme was introduced. In addition to conventional control from the main control room, the beam on-and-off function can be directly controlled from the target room operation area, allowing users to precisely manage beam irradiation. Finally, an integrated control interface was designed to unify the accelerator control system and the target room control system. This integration allows real-time monitoring and control of both accelerator parameters and target room devices, as well as online signal processing and storage of beam parameters such as beam position, profile, and delivered dose. For the construction of the dedicated beamline, preparations were made for amendments to the existing licensing and regulatory approvals. Improvements to the shielding door were required because the current TR104 shielding door was designed for high-dose irradiation using a plug-type structure. For low-dose radiation testing, relocation of the shielding door and the addition of a simplified access door were planned, referencing the proven design of the TR102 beamline. In addition, a space environment simulation multi-chamber, which has already been developed, is planned for permanent installation in the TR104 target room to support a wider range of radiation test applications [ 9 ]. 4. SUMMARY A dedicated proton beamline for radiation hardness testing of semiconductor devices at KOMAC has been designed and its key components have been developed. The beamline is connected to the existing 100 MeV proton accelerator and optimized to provide a large-area flat-top beam with a size of 100 mm × 100 mm and a uniformity better than ± 10%, while reducing the beam intensity to levels suitable for semiconductor irradiation experiments. Beam dynamics simulations were carried out to evaluate different magnet configurations using quadrupole and octupole magnets. The simulation results demonstrated that the proposed optics layout can achieve the required beam size and uniformity within the geometrical constraints of the penetration pipe. A water-cooled graphite-based collimator was designed to withstand an average beam power of up to 800 W, and coupled thermal–structural analyses confirmed that the temperature rise and thermal stresses remain within safe limits. Shielding analyses further verified that the radiation dose rates around the collimator satisfy safety requirements. Two octupole electromagnets were designed, fabricated, and experimentally characterized to generate a wide and uniform transverse beam profile. Magnetic field measurements showed good agreement with simulation results, with less than 1% deviation in the third-order field gradient and effective magnetic field length, confirming the reliability of the magnet design and fabrication. In addition, a dedicated target room for semiconductor radiation testing was designed to support displacement damage and single event effect tests. The target room incorporates real-time beam diagnostics, redundant beam on-and-off control, and an integrated control interface with the accelerator system, enabling efficient beam operation and improved beam quality assurance. The facility layout, material selection, and motion control scheme were optimized to minimize radiation-induced activation and ensure safe operation. Once constructed, the proposed beamline is expected to significantly expand the proton irradiation capabilities at KOMAC and alleviate the growing demand for beam time from the semiconductor industry and related research fields. Declarations FUNDING This work has been supported through KOMAC operation fund of KAERI by Ministry of Science and ICT, the Korean government (KAERI ID: 524620-26) and RS-2025-02315930. Author Contribution H. S. Kim and S. H. Lee wrote the main manuscript text. S. P. Yun prepared figures 4-6 and D. H. Kim prepared figures 7-11. All authors reviewed the manuscript. References N.Tsoupas et. al, Phys. Rev. Accel. Beams 10, 024701 (2007) Y. Yuri, T. Ishizaka, T.Yuyama , I. Ishibori and S. Okumura, Proceeding of IPAC’10, Kyoto, Japan Han-Sung Kim, Hyeok-Jung Kwon, Kui-Young Kim, Jae-Sang Lee, Yujong Kim, J. Korean Phys. Soc . 80 , 799, (2022) Ji-Ho Jang, Hyeok-Jung Kwon and Yong-Sub Cho, J. Korean. Phys. Soc . 59 , 604 (2011) S.P. Yun, H. J. Kwon, H. S. Kim, S. G. Lee, C. Kim, Y. G. Song and D. I. Kim, MOPIK038, Proc. IPAC2017 (2017) Y.M. Kim, S. P. Yun, H. S. Kim and H. J. Kwon, Nucl. Instrum. Methods Phys. Res . A 950, 162971 (2020) H.J. Kwon, S. Lee, H. S. Kim, J. J. Dang, D. H. Kim and S. P. Yun, Error Analysis of the Low Flux Beam Line at KOMAC, KNS Autumn Meeting 2022 D.Uriot and N. Pichoff , TraceWin user manual, CEA Saclay http://irfu.cea.fr/dacm/logiciels/ Han-Sung Kim, Hyeok-Jung Kwon, Seung-Hyun Lee, Dong-Hwan Kim, Sang-Pil Yun, J. Korean Phys. Soc . 83 , 416, (2023) Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 22 Feb, 2026 Reviews received at journal 21 Feb, 2026 Reviewers agreed at journal 12 Feb, 2026 Reviewers invited by journal 11 Feb, 2026 Editor assigned by journal 06 Feb, 2026 Submission checks completed at journal 06 Feb, 2026 First submitted to journal 24 Jan, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8686527","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":590051460,"identity":"b7c0740e-6a2c-4bd4-b0fd-cb80c3a7a495","order_by":0,"name":"Han-Sung 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12:08:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8686527/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8686527/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102855798,"identity":"a469f591-acec-43a9-a0e7-1e18c92598fe","added_by":"auto","created_at":"2026-02-17 14:57:37","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":156086,"visible":true,"origin":"","legend":"\u003cp\u003eThe schematic of the new beamline for semiconductor radiation hardness testing at KOMAC.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/f6a013c917aec2038d00f4c0.png"},{"id":102855817,"identity":"edb4b600-7344-474c-9b3a-69c19dbff954","added_by":"auto","created_at":"2026-02-17 14:57:41","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":186971,"visible":true,"origin":"","legend":"\u003cp\u003eSimulation results of Design 1 : (a) envelop calculation, (b) particle distribution at the target position and (c) uniformity calculation in 100×100 mm\u003csup\u003e2\u003c/sup\u003e at the target position.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/c3e3a3360408ccd9163e0544.png"},{"id":102855824,"identity":"538a1f46-ede7-4f27-bc93-2a3993899032","added_by":"auto","created_at":"2026-02-17 14:57:43","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":191901,"visible":true,"origin":"","legend":"\u003cp\u003eSimulation results of Design 2 : (a) envelop calculation, (b) particle distribution at the target position and (c) uniformity calculation in 100×100 mm\u003csup\u003e2\u003c/sup\u003e at the target position.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/ac718710c44e8dfb022c0586.png"},{"id":102963772,"identity":"877f5c33-ea5a-4312-9ec1-b0536f6f72a0","added_by":"auto","created_at":"2026-02-19 04:20:31","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":147904,"visible":true,"origin":"","legend":"\u003cp\u003eDrawing of the beamline collimator.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/4d0e3ff1f21335c77742909d.png"},{"id":102855797,"identity":"8929f60e-6693-49de-9016-1c3b369a75f4","added_by":"auto","created_at":"2026-02-17 14:57:37","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":358163,"visible":true,"origin":"","legend":"\u003cp\u003eFabricated beamline collimator.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/0b18a957df276f599aeb60d1.png"},{"id":104397423,"identity":"af0c9cb4-558e-460b-90f5-e72a4429c9e1","added_by":"auto","created_at":"2026-03-11 11:47:54","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":109358,"visible":true,"origin":"","legend":"\u003cp\u003eModel for radiation shielding for beamline collimator.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/d74ea30622d73e6f1428013b.png"},{"id":102855799,"identity":"8ad0f4b0-0f4b-4e93-b168-db9a1ffa6493","added_by":"auto","created_at":"2026-02-17 14:57:37","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":507938,"visible":true,"origin":"","legend":"\u003cp\u003e(Top) Dimension of the designed octupole magnet (Bottom) Calculated magnetic field distribution.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/04ff7ef26f9b80b6e8d2a130.png"},{"id":102855819,"identity":"f90e3d7f-a607-4093-a2e3-d37be7ec17e0","added_by":"auto","created_at":"2026-02-17 14:57:42","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":98293,"visible":true,"origin":"","legend":"\u003cp\u003eCalculated magnetic flux density distributions at three longitudinal positions: the magnet center (z = 0 mm), just inside the effective field boundary (z = 100 mm), and just outside the effective field boundary (z = 120 mm).\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/b63f4b29a70b34ff5b2aca55.png"},{"id":102855823,"identity":"d86a3e1e-1c43-4b54-8ba1-b23fb28f708c","added_by":"auto","created_at":"2026-02-17 14:57:43","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":590050,"visible":true,"origin":"","legend":"\u003cp\u003eFabricated octupole magnet, showing the octagonal yoke, pole pieces, and coil arrangement.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/6249f1e4da4b7927eca3801d.png"},{"id":102855805,"identity":"c9ddfa32-7139-4c49-b5f0-9361b129d29f","added_by":"auto","created_at":"2026-02-17 14:57:40","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":42927,"visible":true,"origin":"","legend":"\u003cp\u003eComparison between calculated and measured field profile of the octupole electromagnet as a function of transverse position at a coil current of 29.5 A.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/8a620bb163f17eccb9517dcb.png"},{"id":102855833,"identity":"3c75c5ac-a21d-43fd-a5f5-2d89944808b8","added_by":"auto","created_at":"2026-02-17 14:57:44","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":86670,"visible":true,"origin":"","legend":"\u003cp\u003eMeasured magnetic field distribution along the beam axis at a coil current of 29.5 A.\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/d455e29360fd7b2eb8d3f9ad.png"},{"id":102855822,"identity":"d2dbee5a-059a-40a4-9b98-9efde56d7475","added_by":"auto","created_at":"2026-02-17 14:57:42","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":251175,"visible":true,"origin":"","legend":"\u003cp\u003e(Left) Beam instruments in target room, (Right) thermal-vacuum chamber for space semiconductor testing.\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/1b0002f470b9481fe3c64bc2.png"},{"id":104410211,"identity":"25e44e7e-45f3-4caf-ae75-3650f9e42ab3","added_by":"auto","created_at":"2026-03-11 12:50:06","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3303582,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8686527/v1/7e890083-c2c8-419f-a5ae-71f61db6484f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Design of a Proton Beamline Specialized for Radiation Testing of Semiconductors at KOMAC","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eThe assessment of semiconductor characteristics in response to radiation is a critical function performed at many proton beam facilities. The National Aeronautics and Space Administration (NASA) conducts radiation tolerance tests for space and aviation components [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], similar to efforts by the European Space Agency (ESA) and Japan Aerospace Exploration Agency (JAXA) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. These organizations operate independently or collaboratively utilize global facilities to perform these essential tests. The Korea Multipurpose Accelerator Complex (KOMAC) has been operating a low-flux beamline for radiation testing of semiconductors, which is accredited for JESD89B standard testing [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Despite this, the existing shared use of the beamline limits its availability to domestic users and users from other application fields. At KOMAC, a new beamline is planned to be built for radiation hardness testing of semiconductors. In this paper, we present a design study and development status of a beamline specialized for semiconductor radiation hardness testing at KOMAC.\u003c/p\u003e"},{"header":"2. BEAMLINE DESIGN","content":"\u003cp\u003eThe new beamline for semiconductor radiation hardness testing connects to TR104 on one of the 100 MeV beamlines, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. This beamline will feature a collimator, beam optics to create uniform beam profiles, and various beam diagnostics. A collimator will be installed to reduce the beam flux to 1/10,000. A graphite collimator with a 10 mm diameter aperture will significantly reduce the beam intensity, with most of the beam power being dissipated in the collimator. Additionally, a set of two octupole magnets and a quadrupole magnet will be installed to transform a Gaussian beam profile into a flat-top profile. Beam diagnostics such as an AC Current Transformer (ACCT), a stripline-type Beam Position Monitor (BPM), and a Faraday cup will be installed along the beamline. Furthermore, a 2D array ionization chamber will be installed at the target position to measure the transverse beam profile. In this section, we present the design specifications and simulation results that meet our design goals.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Design Specifications\u003c/h2\u003e \u003cp\u003eWe aim to produce a beam of 100 mm \u0026times; 100 mm with uniformity better than \u0026plusmn;\u0026thinsp;10%. The design specifications are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. After passing through the collimator in the new beamline and broadening into a flat beam profile, the beam intensity can be as low as 10\u003csup\u003e5\u003c/sup\u003e protons/cm\u003csup\u003e2\u003c/sup\u003e per pulse.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eKey design specification of the new beamline for semiconductor radiation hardness testing at KOMAC\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDesign value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBeam Energy at target\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e33\u0026thinsp;~\u0026thinsp;100 MeV\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMax. average power at collimator\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e800 W\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMax. average beam current at target\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 nA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBeam size at target\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100 mm \u0026times; 100 mm\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBeam uniformity at target\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;10%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe diameter of the penetration pipe between the beamline and the target room is 180 mm. To satisfy the design specifications given in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e with the narrower penetration pipe compared to the low-flux beamline (i.e. the beamline to TR102 [\u003cspan additionalcitationids=\"CR5 CR6\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]), we have re-positioned the beam optics.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Beam Dynamics Analysis\u003c/h2\u003e \u003cp\u003eThe beam dynamics simulation was performed from the collimator to the target position in TR104. Input beam parameter used in the simulation is given in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The beam profile should be spread as much as possible while passing through the penetration pipe, with minimal beam loss. Two designs are considered for the beamline optics: 1) an octupole-quadrupole-octupole magnet configuration, and 2) a quadrupole-quadrupole-octupole-octupole magnet configuration. The first design (Design 1) is similar to the configuration used in the low-flux beamline to TR102. By adjusting the positions of the octupole-quadrupole-octupole magnets towards the end of the beamline and fine-tuning the distances between them, the beam size and uniformity are maximized, even with a smaller diameter penetration pipe. The results of Design 1 are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Particle and envelope calculations are performed using TraceWin code [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eInput beam parameter used in the simulation\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBeam Parameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ex, y\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003erms norm. emittance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.225 π mm mrad\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eα\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eβ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.3 mm/π mrad\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn Design 2, an additional quadrupole magnet is used to achieve a flat-top distribution in both the x and y directions. The results of Design 2 are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Design 1 can provide a significantly larger beam area while satisfying the beam uniformity within \u0026plusmn;\u0026thinsp;10%; however, it results in higher beam loss compared to Design 2. Although Design 2 exhibits much lower beam loss, it is anticipated that optics adjustments will be challenging to achieve an increased flat beam area.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. MAJOR COMPONENTS DEVELOPMENT","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Water-cooled Collimator\u003c/h2\u003e \u003cp\u003eThe beamline collimator was designed to shape the proton beam intensity to meet the requirements of a dedicated beamline for radiation testing of semiconductor devices (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Its primary function is to reduce the peak beam current while maintaining stable beam conditions suitable for irradiation experiments. Considering a thermal load of 800 W and radiation-induced activation, the collimator was fabricated using three materials: graphite, copper, and SUS316L stainless steel. A coupled thermal\u0026ndash;structural analysis was performed to evaluate the temperature rise due to beam-induced heating, the resulting thermal stresses, and the mechanical stability of the interfaces between dissimilar materials with different coefficients of thermal expansion.\u003c/p\u003e \u003cp\u003eThe thermal analysis was conducted assuming a Gaussian round beam with a standard deviation of σ of 15 mm and a total beam power of 800 W. The beam was vertically offset by 40 mm from the beamline center in order to utilize the beam edge and thereby reduce the beam flux to approximately 0.1%. Water cooling was applied with a flow velocity of 2.5 m/s at an inlet temperature of 27\u0026deg;C through circular cooling channels with a diameter of 10 mm, corresponding to a convective heat transfer coefficient of 10,646 W/m\u0026sup2;\u0026middot;K. The analysis results showed that the maximum temperature of the entire collimator was 100.41\u0026deg;C, which occurred in the graphite part. The maximum temperatures of the copper and SUS316L parts were 32.56\u0026deg;C and 30.93\u0026deg;C, respectively. The temperature increases in all components were well below the melting or sublimation temperatures of the respective materials. In addition, the temperature rise in the cooling channel region of the copper part remained below the boiling point of water. Therefore, the thermal load induced by the proton beam was judged to be within a safe operating range.\u003c/p\u003e \u003cp\u003eBased on the temperature distribution obtained from the thermal analysis, a coupled structural analysis was performed. All contact interfaces between different components were assumed to be perfectly bonded. The maximum von Mises stresses were evaluated as 1.61 MPa for the graphite part, 27.45 MPa for the copper part, and 71.26 MPa for the SUS316L part. At the material interfaces, the maximum von Mises stresses were 6.62 MPa at the graphite\u0026ndash;copper interface and 28.37 MPa at the copper\u0026ndash;SUS316L interface. All evaluated stresses were below the yield strengths of the corresponding materials, indicating that the thermal stresses induced by beam heating are within safe limits.\u003c/p\u003e \u003cp\u003eThe beamline collimator consists of three main components: a graphite beam absorber, an oxygen-free copper (OFC) cooling jacket, and a SUS316L stainless steel collimator housing. The graphite beam absorber was machined using a multi-axis machining tool, including the fabrication of a 10 mm diameter hole. The cooling jacket and housing were assembled through a brazing process between the oxygen-free copper and stainless-steel components. Since a high vacuum is maintained inside the collimator, helium leak tests were performed on the cooling channels, yielding a leak rate of 1.0 \u0026times; 10⁻⁹ Torr\u0026middot;L/s. During final assembly, the graphite beam absorber was pressed against the copper cooling jacket using twelve bolts to enhance the thermal contact between the components. Helium leak tests were again conducted after assembly to verify vacuum tightness. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows the fabricated beamline collimator.\u003c/p\u003e \u003cp\u003eA shielding analysis was performed to evaluate the attenuation of neutrons and gamma rays generated when an 800 nA proton beam impinges on the collimator. The dose rates were assessed at locations accessible to personnel, including the corridor-side wall and the exterior wall of the facility. The shielding geometry used in the radiation transport calculations is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The calculated maximum dose rate was 8.49 \u0026micro;Sv/h (relative error 1.77%) on the corridor side and 0.144 \u0026micro;Sv/h (relative error 9.88%) on the exterior side of the building, indicating that the shielding design satisfies radiation safety requirements.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Octupole Magnet for Beam Expansion\u003c/h2\u003e \u003cp\u003eThe octupole electromagnets generate higher-order multipole magnetic fields and are generally employed to suppress beam halo and correct nonlinear beam aberrations. Owing to the cubic dependence of the magnetic force on the distance from the magnet center, two identical octupole magnets were designed and fabricated to flatten both horizontal and vertical transverse beam profiles in a dedicated beamline for radiation testing of semiconductor devices.\u003c/p\u003e \u003cp\u003eThe octupole magnet was designed to satisfy the required pole field, third-order field gradient, and effective magnetic field length. The yoke has a regular octagonal shape with a longitudinal length of 226 mm and chamfered corners to reduce fringe fields. Semicircular pole tips with a radius of 20 mm form a bore diameter of 110 mm. The excitation coils were wound in a stepped configuration with 88 turns per pole.\u003c/p\u003e \u003cp\u003eThree-dimensional magnetostatic simulations were performed using CST Studio Suite. The calculated magnetic flux density distribution at the longitudinal center of the magnet shows a clear null point at the center and a rapid increase in field strength with radial distance, consistent with an ideal octupole field (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe magnetic field distributions were further examined at multiple longitudinal positions, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e. Circular symmetry was well preserved within the effective field region, while a residual fringe field of approximately 0.05 T was observed near the pole tips just outside the effective field boundary. Under a maximum operating current of 30 A, the magnet achieved a pole field of 0.12 T, a third-order field gradient of 8,539 T/m\u0026sup3;, and an effective magnetic field length of approximately 226 mm without magnetic saturation.\u003c/p\u003e \u003cp\u003eTwo octupole electromagnet assemblies were fabricated, including cooling, mechanical alignment, and electrical systems (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e). Dimensional inspection and electrical and cooling tests confirmed that the fabricated magnets satisfied the design specifications. Magnetic field measurements were conducted at a coil current of 29.5 A. The measurement results of are summarized in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e. The measured third-order field gradients were 8,316 T/m\u0026sup3; and 8,330 T/m\u0026sup3; for magnets #1 and #2, respectively, which differ by less than 1% from the simulated value. The measured effective magnetic field lengths ranged from 216 to 225 mm. These results confirm that the fabricated octupole electromagnets meet the performance requirements for transverse beam profile control in the radiation-test beamline. After completing all operational and magnetic field tests, the principal specifications and performance parameters of the fabricated octupole electromagnets are summarized as follows:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eTotal excitation: 2,640 A\u0026middot;turns/pole (maximum 4,350 A\u0026middot;turns/pole)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003ePole field: ~0.231 T (maximum 0.341 T)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eThird-order field gradient (K₃): ~8,330 T/m\u0026sup3; (maximum 12,296 T/m\u0026sup3;)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eEffective magnetic field length: ~223 mm (maximum 227 mm)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003ePower consumption: 30 A, 13.9 V (maximum current 49.4 A)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eCooling water flow rate: 5.16 L/h per coil (maximum 14 L/h per coil)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003ePressure drop: 2.2 bar (ΔT\u0026thinsp;=\u0026thinsp;20\u0026deg;C), maximum 3 bar\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eWeight: ~275 kg\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Target Room for Semiconductor Testing\u003c/h2\u003e \u003cp\u003eA dedicated radiation test target room based on a 100 MeV proton accelerator was designed to support radiation effects testing of semiconductor devices, including displacement damage and single event effect (SEE) tests. The configuration and layout of the proton beam irradiation target room were determined with reference to the existing TR102 beamline. The target room is optimized to meet the key requirements for proton-beam-based soft error testing of semiconductor devices. The principal design parameters are as follows: proton beam energy of 20\u0026ndash;100 MeV, beam fluence ranging from 1 \u0026times; 10⁵ to 1 \u0026times; 10⁹ cm⁻\u0026sup2;, a typical beam size of 100 mm \u0026times; 100 mm, beam uniformity within \u0026plusmn;\u0026thinsp;10%, and an external beam irradiation mode. The irradiation target room has dimensions of 4 m \u0026times; 4 m \u0026times; 3 m (width \u0026times; length \u0026times; height). To satisfy these requirements, the target room includes a beam window, beam shutter, defining and test collimators, transmission and monitoring ionization chambers, a range modulator (ridge filter), an energy degrader, a beam dump, a device-under-test (DUT) support structure with a universal sample holder, and a radiation monitoring system (RMS), as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e. To prevent malfunction caused by secondary radiation during irradiation, pneumatic cylinders were adopted for motion control instead of electric motors. In addition, low-activation materials such as graphite, engineering plastics, and aluminum alloys were preferentially used for all components to minimize radiation-induced activation and occupational exposure.\u003c/p\u003e \u003cp\u003eTo enhance operational efficiency and beam quality assurance, several key features were incorporated into the target room design. First, in-situ and real-time beam diagnostics were implemented to continuously monitor the beam profile, position, and intensity of the proton beam extracted through the beam window during irradiation. This capability enables operators in the control room to perform efficient beam tuning and significantly reduces beam preparation time, thereby increasing the effective beam time available to users.\u003c/p\u003e \u003cp\u003eSecond, a redundant beam on-and-off control scheme was introduced. In addition to conventional control from the main control room, the beam on-and-off function can be directly controlled from the target room operation area, allowing users to precisely manage beam irradiation.\u003c/p\u003e \u003cp\u003eFinally, an integrated control interface was designed to unify the accelerator control system and the target room control system. This integration allows real-time monitoring and control of both accelerator parameters and target room devices, as well as online signal processing and storage of beam parameters such as beam position, profile, and delivered dose.\u003c/p\u003e \u003cp\u003eFor the construction of the dedicated beamline, preparations were made for amendments to the existing licensing and regulatory approvals. Improvements to the shielding door were required because the current TR104 shielding door was designed for high-dose irradiation using a plug-type structure. For low-dose radiation testing, relocation of the shielding door and the addition of a simplified access door were planned, referencing the proven design of the TR102 beamline. In addition, a space environment simulation multi-chamber, which has already been developed, is planned for permanent installation in the TR104 target room to support a wider range of radiation test applications [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e"},{"header":"4. SUMMARY","content":"\u003cp\u003eA dedicated proton beamline for radiation hardness testing of semiconductor devices at KOMAC has been designed and its key components have been developed. The beamline is connected to the existing 100 MeV proton accelerator and optimized to provide a large-area flat-top beam with a size of 100 mm \u0026times; 100 mm and a uniformity better than \u0026plusmn;\u0026thinsp;10%, while reducing the beam intensity to levels suitable for semiconductor irradiation experiments.\u003c/p\u003e \u003cp\u003eBeam dynamics simulations were carried out to evaluate different magnet configurations using quadrupole and octupole magnets. The simulation results demonstrated that the proposed optics layout can achieve the required beam size and uniformity within the geometrical constraints of the penetration pipe. A water-cooled graphite-based collimator was designed to withstand an average beam power of up to 800 W, and coupled thermal\u0026ndash;structural analyses confirmed that the temperature rise and thermal stresses remain within safe limits. Shielding analyses further verified that the radiation dose rates around the collimator satisfy safety requirements. Two octupole electromagnets were designed, fabricated, and experimentally characterized to generate a wide and uniform transverse beam profile. Magnetic field measurements showed good agreement with simulation results, with less than 1% deviation in the third-order field gradient and effective magnetic field length, confirming the reliability of the magnet design and fabrication.\u003c/p\u003e \u003cp\u003eIn addition, a dedicated target room for semiconductor radiation testing was designed to support displacement damage and single event effect tests. The target room incorporates real-time beam diagnostics, redundant beam on-and-off control, and an integrated control interface with the accelerator system, enabling efficient beam operation and improved beam quality assurance. The facility layout, material selection, and motion control scheme were optimized to minimize radiation-induced activation and ensure safe operation.\u003c/p\u003e \u003cp\u003eOnce constructed, the proposed beamline is expected to significantly expand the proton irradiation capabilities at KOMAC and alleviate the growing demand for beam time from the semiconductor industry and related research fields.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFUNDING\u003c/h2\u003e \u003cp\u003eThis work has been supported through KOMAC operation fund of KAERI by Ministry of Science and ICT, the Korean government (KAERI ID: 524620-26) and RS-2025-02315930.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eH. S. Kim and S. H. Lee wrote the main manuscript text. S. P. Yun prepared figures 4-6 and D. H. Kim prepared figures 7-11. All authors reviewed the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eN.Tsoupas et. al, Phys. Rev. Accel. Beams 10, 024701 (2007)\u003c/li\u003e\n\u003cli\u003eY. Yuri, T. Ishizaka, T.Yuyama , I. Ishibori and S. Okumura, Proceeding of IPAC\u0026rsquo;10, Kyoto, Japan\u003c/li\u003e\n\u003cli\u003eHan-Sung Kim, Hyeok-Jung Kwon, Kui-Young Kim, Jae-Sang Lee, Yujong Kim, \u003cem\u003eJ. Korean Phys. Soc\u003c/em\u003e. \u003cstrong\u003e80\u003c/strong\u003e, 799, (2022)\u003c/li\u003e\n\u003cli\u003eJi-Ho Jang, Hyeok-Jung Kwon and Yong-Sub Cho, \u003cem\u003eJ. Korean. Phys. Soc\u003c/em\u003e. \u003cstrong\u003e59\u003c/strong\u003e, 604 (2011)\u003c/li\u003e\n\u003cli\u003eS.P. Yun, H. J. Kwon, H. S. Kim, S. G. Lee, C. Kim, Y. G. Song and D. I. Kim, MOPIK038, Proc. IPAC2017 (2017)\u003c/li\u003e\n\u003cli\u003eY.M. Kim, S. P. Yun, H. S. Kim and H. J. Kwon, \u003cem\u003eNucl. Instrum. Methods Phys. Res\u003c/em\u003e. A 950, 162971 (2020)\u003c/li\u003e\n\u003cli\u003eH.J. Kwon, S. Lee, H. S. Kim, J. J. Dang, D. H. Kim and S. P. Yun, Error Analysis of the Low Flux Beam Line at KOMAC, KNS Autumn Meeting 2022\u003c/li\u003e\n\u003cli\u003eD.Uriot and N. Pichoff , TraceWin user manual, CEA Saclay http://irfu.cea.fr/dacm/logiciels/\u003c/li\u003e\n\u003cli\u003eHan-Sung Kim, Hyeok-Jung Kwon, Seung-Hyun Lee, Dong-Hwan Kim, Sang-Pil Yun, \u003cem\u003eJ. Korean Phys. Soc\u003c/em\u003e. \u003cstrong\u003e83\u003c/strong\u003e, 416, (2023)\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-the-korean-physical-society","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Journal of the Korean Physical Society](https://link.springer.com/journal/40042)","snPcode":"40042","submissionUrl":"https://submission.springernature.com/new-submission/40042/3","title":"Journal of the Korean Physical Society","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"KOMAC, Beamline, Radiation test, Semiconductor","lastPublishedDoi":"10.21203/rs.3.rs-8686527/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8686527/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe demand for radiation hardness testing of semiconductor devices has been rapidly increasing, particularly for space and high-reliability applications. To address this need, a dedicated proton beamline for semiconductor radiation testing is being developed at the Korea Multi-purpose Accelerator Complex (KOMAC) using an existing 100 MeV proton accelerator. The beamline is designed to deliver a large-area, low-flux proton beam suitable for displacement damage and single event effect tests. The beamline incorporates a graphite-based water-cooled collimator to reduce the beam intensity and a magnet optics system consisting of quadrupole and octupole magnets to generate a wide and uniform flat-top beam profile. Beam dynamics simulations were performed to evaluate different optics configurations under the geometrical constraints of the penetration pipe. The simulation results demonstrate that a beam size of 100 mm \u0026times; 100 mm with a uniformity better than \u0026plusmn;\u0026thinsp;10% can be achieved. The collimator was designed to withstand an average beam power of up to 800 W, and coupled thermal\u0026ndash;structural analyses confirmed that both temperature rise and thermal stresses remain within safe limits. Radiation shielding analyses further verified that the resulting dose rates satisfy radiation safety requirements. In addition, two octupole electromagnets were designed, fabricated, and experimentally characterized, showing good agreement between measured and simulated magnetic field properties. A dedicated target room was also designed to support efficient semiconductor irradiation experiments, featuring real-time beam diagnostics, redundant beam on-and-off control, and an integrated control interface with the accelerator system. The proposed beamline is expected to significantly enhance proton irradiation capabilities at KOMAC and provide an effective testing platform for the semiconductor industry and related research fields.\u003c/p\u003e","manuscriptTitle":"Design of a Proton Beamline Specialized for Radiation Testing of Semiconductors at KOMAC","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-17 14:57:05","doi":"10.21203/rs.3.rs-8686527/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-22T13:16:27+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-22T02:05:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"159575068760493433899080179664103563221","date":"2026-02-12T06:38:02+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-12T02:49:19+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-07T02:23:57+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-06T08:40:21+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of the Korean Physical Society","date":"2026-01-24T11:48:46+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-the-korean-physical-society","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Journal of the Korean Physical Society](https://link.springer.com/journal/40042)","snPcode":"40042","submissionUrl":"https://submission.springernature.com/new-submission/40042/3","title":"Journal of the Korean Physical Society","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"18a636ae-5ac3-48be-80d3-29a8d2ca9461","owner":[],"postedDate":"February 17th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-04T09:09:54+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-17 14:57:05","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8686527","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8686527","identity":"rs-8686527","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}