Etching a narrow bridge on REBa2Cu3O7-x (REBCO, RE = Rare Earth) tape is a widely applied procedure during transport measurements of critical current (Ic), aiming to mitigate significant Lorentz forces. However, the microbridge can influence the measurement accuracy, and understanding this influence is crucial because it can bias the extrapolation of Ic to the full tape width. In this article, we reveal that the microbridge could result in an overestimation when extrapolating the full-width Ic values from microbridge ones. We identified two primary sources of this overestimation by systematically comparing the directly measured full-width Ic values with those extrapolated from narrow bridges under varying temperatures, applied magnetic fields, and field orientations. The first source arises from inaccuracies in the assumed cross-sectional geometry and area of the narrow bridge. Specifically, assuming a rectangular cross-section when the actual geometry is trapezoidal leads to significant overestimations. The second factor is the nonuniform pinning effect across the thickness of the REBCO layer. Although this effect is negligible at low magnetic fields and higher temperatures, it becomes significant at lower temperatures, high magnetic fields, and when the field is nearly parallel to the tape surface. Based on these findings, we propose an improved procedure for transport measurements using narrow bridges to achieve more accurate determinations of Ic.
在REBa2Cu3O7-x （REBCO, RE = Rare Earth）胶带上蚀刻窄桥是一种广泛应用于临界电流（Ic）输运测量的方法，旨在减轻显著的洛伦兹力。然而，微桥会影响测量精度，了解这种影响是至关重要的，因为它会使Ic的外推偏向于整个带宽度。在本文中，我们揭示了当从微桥的值推断全宽度Ic值时，微桥可能导致高估。我们通过系统地比较直接测量的全宽Ic值与在不同温度、外加磁场和场方向下从窄桥推断的Ic值，确定了这种高估的两个主要来源。第一个原因是假定的窄桥的横截面几何形状和面积不准确。具体来说，当实际几何形状为梯形时，假设截面为矩形会导致严重的高估。第二个因素是跨REBCO层厚度的不均匀钉住效应。虽然这种效应在低磁场和高温下可以忽略不计，但在较低温度、高磁场和磁场几乎与纸带表面平行时，这种效应就会变得显著。基于这些发现，我们提出了一种改进的程序，运输测量使用窄桥，以实现更准确的测定Ic。
{"title":"Possible Overestimation of Ic Value of REBCO Tapes Due to the Narrow Bridge Fabricated by Laser Etching During Transport Measurements","authors":"Qi Yuan;Zili Zhang;Xiaowei Song;Jie Yang;Benzhe Zhou;Shuo Li;Zhen Wang;Gang Li;Jun Luo;Rui Zhou;Lei Wang;Quanliang Cao;Jinguang Cheng","doi":"10.1109/TASC.2026.3657800","DOIUrl":"https://doi.org/10.1109/TASC.2026.3657800","url":null,"abstract":"Etching a narrow bridge on REBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> (REBCO, RE = Rare Earth) tape is a widely applied procedure during transport measurements of critical current (<italic>I</i><sub>c</sub>), aiming to mitigate significant Lorentz forces. However, the microbridge can influence the measurement accuracy, and understanding this influence is crucial because it can bias the extrapolation of <italic>I<sub>c</sub></i> to the full tape width. In this article, we reveal that the microbridge could result in an overestimation when extrapolating the full-width <italic>I</i><sub>c</sub> values from microbridge ones. We identified two primary sources of this overestimation by systematically comparing the directly measured full-width <italic>I</i><sub>c</sub> values with those extrapolated from narrow bridges under varying temperatures, applied magnetic fields, and field orientations. The first source arises from inaccuracies in the assumed cross-sectional geometry and area of the narrow bridge. Specifically, assuming a rectangular cross-section when the actual geometry is trapezoidal leads to significant overestimations. The second factor is the nonuniform pinning effect across the thickness of the REBCO layer. Although this effect is negligible at low magnetic fields and higher temperatures, it becomes significant at lower temperatures, high magnetic fields, and when the field is nearly parallel to the tape surface. Based on these findings, we propose an improved procedure for transport measurements using narrow bridges to achieve more accurate determinations of <italic>I</i><sub>c</sub>.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 2","pages":"1-13"},"PeriodicalIF":1.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-26DOI: 10.1109/TASC.2026.3657580
Frederick S. Porter;Gregory V. Brown;Renata S. Cumbee;Megan E. Eckart;Natalie Hell;Richard L. Kelley;Caroline A. Kilbourne;Maurice A. Leutenegger;Thomas Lockard;Makoto Sawada;Chintan D. Shah;Stephen J. Smith;Michael C. Witthoeft
Space X-ray spectrometers such as the Resolve instrument on XRISM require precise calibration in order to interpret the spectra of astrophysical objects. Key components of the calibration are the energy scale and the core line spread function, both of which vary with photon energy. A major issue in the calibration of high-resolution spectrometers is locating good calibrators with well-known and stable intrinsic line shapes. Neutral fluorescence is widely used, but inner-shell transitions in neutral atoms often exhibit complex, poorly documented line shapes that vary with excitation conditions. Here we present empirical measurements of K-shell transitions in neutral O and F below 1 keV using an engineering model XRISM calorimeter array, an electron bombardment modulated X-ray source, and an electron beam ion trap (EBIT) to provide a precise energy reference. In addition, we report measurements of the Mo Lα complex with the transition-edge microcalorimeter spectrometer (TEMS), which reveal strong satellite structure and sensitivity of the line shape to the incident exciting spectrum. Together, these results demonstrate the need for empirical line-shape models, highlight the nonstationary nature of neutral fluorescence features, and define a path toward developing transfer standards for XRISM and future precision instruments such as Athena/X-IFU.
{"title":"Measuring X-Ray Emission Line Shapes in Neutral Species for XRISM Calibration","authors":"Frederick S. Porter;Gregory V. Brown;Renata S. Cumbee;Megan E. Eckart;Natalie Hell;Richard L. Kelley;Caroline A. Kilbourne;Maurice A. Leutenegger;Thomas Lockard;Makoto Sawada;Chintan D. Shah;Stephen J. Smith;Michael C. Witthoeft","doi":"10.1109/TASC.2026.3657580","DOIUrl":"https://doi.org/10.1109/TASC.2026.3657580","url":null,"abstract":"Space X-ray spectrometers such as the Resolve instrument on XRISM require precise calibration in order to interpret the spectra of astrophysical objects. Key components of the calibration are the energy scale and the core line spread function, both of which vary with photon energy. A major issue in the calibration of high-resolution spectrometers is locating good calibrators with well-known and stable intrinsic line shapes. Neutral fluorescence is widely used, but inner-shell transitions in neutral atoms often exhibit complex, poorly documented line shapes that vary with excitation conditions. Here we present empirical measurements of K-shell transitions in neutral O and F below 1 keV using an engineering model XRISM calorimeter array, an electron bombardment modulated X-ray source, and an electron beam ion trap (EBIT) to provide a precise energy reference. In addition, we report measurements of the Mo Lα complex with the transition-edge microcalorimeter spectrometer (TEMS), which reveal strong satellite structure and sensitivity of the line shape to the incident exciting spectrum. Together, these results demonstrate the need for empirical line-shape models, highlight the nonstationary nature of neutral fluorescence features, and define a path toward developing transfer standards for XRISM and future precision instruments such as Athena/X-IFU.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-23DOI: 10.1109/TASC.2026.3657136
Thomas P. Satterthwaite;Zeeshan Ahmed;Cody J. Duell;Shawn W. Henderson;Tristan Pinsonneault-Marotte;Max Silva-Feaver;Yuhan Wang
Fulfilling the science goalsof the Simons Observatory, a state-of-the-art cosmic microwave background experiment, has required deploying tens of thousands of superconducting bolometers. Reading out data from the observatory’s more than 67 000 transition-edge sensor (TES) detectors while maintaining cryogenic conditions requires an effective multiplexing scheme. The SLAC microresonator radio frequency (SMuRF) electronics have been developed to provide the warm electronics for a high-density microwave frequency multiplexing readout system, and this system has been shown to achieve multiplexing factors on the order of 1000. SMuRF has recently been deployed to the Simons Observatory, which is located at 5200 m on Cerro Toco in Chile’s Atacama Desert. As the SMuRF system is exposed to the desert’s diurnal temperature swings, resulting phase drift in radio frequency (RF) transmission lines may introduce a systematic signal contamination. We present studies of phase drift in the room-temperature RF lines of the Simons Observatory’s 6 m large-aperture telescope, which hosts the largest deployment to date of TES microwave frequency multiplexing to a single telescope. We show that these phase drifts occur on time scales, which are significantly longer than sky scanning, and that their contribution to on-sky in-transition detector noise is within the readout noise budget.
{"title":"The Simons Observatory: Studies of Phase Drift in RF Transmission Lines From the First Large-Scale Deployment of Microwave Frequency Multiplexing for Cosmology","authors":"Thomas P. Satterthwaite;Zeeshan Ahmed;Cody J. Duell;Shawn W. Henderson;Tristan Pinsonneault-Marotte;Max Silva-Feaver;Yuhan Wang","doi":"10.1109/TASC.2026.3657136","DOIUrl":"https://doi.org/10.1109/TASC.2026.3657136","url":null,"abstract":"Fulfilling the science goalsof the Simons Observatory, a state-of-the-art cosmic microwave background experiment, has required deploying tens of thousands of superconducting bolometers. Reading out data from the observatory’s more than 67 000 transition-edge sensor (TES) detectors while maintaining cryogenic conditions requires an effective multiplexing scheme. The SLAC microresonator radio frequency (SMuRF) electronics have been developed to provide the warm electronics for a high-density microwave frequency multiplexing readout system, and this system has been shown to achieve multiplexing factors on the order of 1000. SMuRF has recently been deployed to the Simons Observatory, which is located at 5200 m on Cerro Toco in Chile’s Atacama Desert. As the SMuRF system is exposed to the desert’s diurnal temperature swings, resulting phase drift in radio frequency (RF) transmission lines may introduce a systematic signal contamination. We present studies of phase drift in the room-temperature RF lines of the Simons Observatory’s 6 m large-aperture telescope, which hosts the largest deployment to date of TES microwave frequency multiplexing to a single telescope. We show that these phase drifts occur on time scales, which are significantly longer than sky scanning, and that their contribution to on-sky in-transition detector noise is within the readout noise budget.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-23DOI: 10.1109/TASC.2026.3656939
Dongxu Wang;Jinxing Zheng;Xudong Wang;Yudong Lu;Ying Zheng;Haoran Jiang;Chuanbing Cai
Understanding irradiation-induced defect formation in high-temperature superconductors is critical for their application in fusion environments. Here, we use Molecular Dynamics (MD) simulations to study the damage evolution in YBa2Cu3O7-δ (YBCO) under 270 keV proton irradiation. We introduce a depth-resolved analysis framework that accounts for energy deposition and dissipation during proton penetration. Our results show that defects primarily stem from disruptions at Cu and O sites, with defect densities peaking in surface layers for [001] direction collisions. The defect population is found to be highly sensitive to the interatomic potential, as evidenced by the differences between the Gray and Chaplot potentials. In addition, the defect morphology and Frenkel pair distributions are strongly depth-dependent, with severe surface damage gradually diminishing at greater depths. Thermal analysis indicates that displacement cascades cause transient lattice heating, which stabilizes as the cascade evolves. The simulated defect structures (6.34 nm to 10.27 nm) align well with our experimental transmission electron microscopy (TEM) observations (7.8 nm to 12.3 nm). These findings provide atomistic insights into the directional, thermal, and depth-dependent characteristics of radiation damage in YBCO.
{"title":"Proton Irradiation-Induced Defect Formation and Evolution in YBa2Cu3O7-δ: A Molecular Dynamics Study","authors":"Dongxu Wang;Jinxing Zheng;Xudong Wang;Yudong Lu;Ying Zheng;Haoran Jiang;Chuanbing Cai","doi":"10.1109/TASC.2026.3656939","DOIUrl":"https://doi.org/10.1109/TASC.2026.3656939","url":null,"abstract":"Understanding irradiation-induced defect formation in high-temperature superconductors is critical for their application in fusion environments. Here, we use Molecular Dynamics (MD) simulations to study the damage evolution in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> (YBCO) under 270 keV proton irradiation. We introduce a depth-resolved analysis framework that accounts for energy deposition and dissipation during proton penetration. Our results show that defects primarily stem from disruptions at Cu and O sites, with defect densities peaking in surface layers for [001] direction collisions. The defect population is found to be highly sensitive to the interatomic potential, as evidenced by the differences between the Gray and Chaplot potentials. In addition, the defect morphology and Frenkel pair distributions are strongly depth-dependent, with severe surface damage gradually diminishing at greater depths. Thermal analysis indicates that displacement cascades cause transient lattice heating, which stabilizes as the cascade evolves. The simulated defect structures (6.34 nm to 10.27 nm) align well with our experimental transmission electron microscopy (TEM) observations (7.8 nm to 12.3 nm). These findings provide atomistic insights into the directional, thermal, and depth-dependent characteristics of radiation damage in YBCO.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 2","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1109/TASC.2026.3656640
Benjamin Poupart-Raîche;Christian Lacroix;Haïfa Ben Saâd;Delano Horn-Bourque;Frédéric Sirois
A thorough understanding of quench dynamics in REBCO tapes is essential for designing reliable quench detection and protection strategies for REBCO-based superconducting devices. The minimum quench energy (MQE) is commonly employed as a key design parameter by magnet engineers for this purpose. Previous work on REBCO conductors has linked the interpretation of MQE to the concept of the minimum propagating zone, historically developed for low-temperature superconducting wires. In this work, the MQE of 1) Regular (i.e., commercial) REBCO tapes and 2) high normal zone propagation velocity (NZPV) REBCO tapes with a current flow diverter (CFD) architecture was experimentally determined and compared. The results show that the MQE scales inversely with the NZPV, demonstrating an intrinsic tradeoff between these two parameters for all sample types. Moreover, a pronounced difference in the voltage developed during quench in Regular tapes compared to CFD tapes indicates distinct underlying physical mechanisms. These findings suggest that, in CFD tapes, the thermal diffusion length governs quench development rather than the minimum propagating zone in Regular tapes.
{"title":"Minimum Quench Energy in REBCO Tapes With a Local Critical Current Reduction","authors":"Benjamin Poupart-Raîche;Christian Lacroix;Haïfa Ben Saâd;Delano Horn-Bourque;Frédéric Sirois","doi":"10.1109/TASC.2026.3656640","DOIUrl":"https://doi.org/10.1109/TASC.2026.3656640","url":null,"abstract":"A thorough understanding of quench dynamics in REBCO tapes is essential for designing reliable quench detection and protection strategies for REBCO-based superconducting devices. The minimum quench energy (MQE) is commonly employed as a key design parameter by magnet engineers for this purpose. Previous work on REBCO conductors has linked the interpretation of MQE to the concept of the minimum propagating zone, historically developed for low-temperature superconducting wires. In this work, the MQE of 1) Regular (i.e., commercial) REBCO tapes and 2) high normal zone propagation velocity (NZPV) REBCO tapes with a current flow diverter (CFD) architecture was experimentally determined and compared. The results show that the MQE scales inversely with the NZPV, demonstrating an intrinsic tradeoff between these two parameters for all sample types. Moreover, a pronounced difference in the voltage developed during quench in Regular tapes compared to CFD tapes indicates distinct underlying physical mechanisms. These findings suggest that, in CFD tapes, the thermal diffusion length governs quench development rather than the minimum propagating zone in Regular tapes.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 7","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A low-temperature diffusion jointing technique based on citric-acid surface activation was applied to directly connect the Cu stabilizing layers of REBCO tapes, and its electrical characteristics were systematically investigated. The effects of joining conditions, such as, pressure, heating time, and joint length on interfacial resistivity were examined to identify the optimal jointing condition, which produced uniform and low-resistance Cu–Cu interfaces. I–V measurements confirmed that the critical current (Ic) and n-value of the jointed tapes showed no significant degradation compared with non-jointed conductors. When applied to two-tape stacked REBCO conductor, the Ic increased by about 1.7 times, indicating efficient current transfer through the joint region. These results demonstrate that the proposed citric-acid-assisted diffusion jointing method enables reliable electrical connections suitable for multi-tape REBCO conductors and provides a promising approach for practical high-temperature superconducting applications.
{"title":"Direct Joining Method of Y-based high-Temperature Superconducting Tapes for Application to High-Current Conductors","authors":"Daisuke Ohkura;Noriko Chikumoto;Michihiko Watanabe;Naoki Hirano;Yuta Onodera;Ryosuke Kodama","doi":"10.1109/TASC.2026.3651234","DOIUrl":"https://doi.org/10.1109/TASC.2026.3651234","url":null,"abstract":"A low-temperature diffusion jointing technique based on citric-acid surface activation was applied to directly connect the Cu stabilizing layers of REBCO tapes, and its electrical characteristics were systematically investigated. The effects of joining conditions, such as, pressure, heating time, and joint length on interfacial resistivity were examined to identify the optimal jointing condition, which produced uniform and low-resistance Cu–Cu interfaces. <italic>I–V</i> measurements confirmed that the critical current (<italic>I</i><sub>c</sub>) and <italic>n</i>-value of the jointed tapes showed no significant degradation compared with non-jointed conductors. When applied to two-tape stacked REBCO conductor, the <italic>I</i><sub>c</sub> increased by about 1.7 times, indicating efficient current transfer through the joint region. These results demonstrate that the proposed citric-acid-assisted diffusion jointing method enables reliable electrical connections suitable for multi-tape REBCO conductors and provides a promising approach for practical high-temperature superconducting applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A superconducting transition edge sensor (TES), a type of photon-number-resolving detector, is essential for quantum information applications that utilize highly nonclassical quantum states. For these applications, TES devices must simultaneously achieve high detection efficiency and high energy resolution. Matching the mode field diameter of optical fibers requires a sufficiently large sensitive area, which introduces an alignment tolerance. However, the increased heat capacity associated with a larger area degrades the energy resolution and consequently reduces the accuracy of the photon-number discrimination. Thus, developing a TES with both a large sensitive area and high energy resolution remains highly challenging. To address this issue, we developed a Ti/Au/Ti/Au four-layer structure TES. Theoretically, stacking metal materials with different Debye temperatures confines high-energy phonon within the TES. This suppression of high-energy phonon loss during energy down-conversion improves the energy collection efficiency, thereby enhancing the energy resolution. Furthermore, lowering the transition temperature through the proximity effect provides additional improvement. Consequently, we evaluated the enhancement of energy resolution resulting from phonon confinement and the reduction in transition temperature. As a result, in contrast to conventional Ti/Au bilayer TESs, the four-layer TES with a size of 21 $mathrm{mu }$m × 21 $mathrm{mu }$m exhibited photon-number-resolving ability at 1550 nm, achieving an energy resolution of 0.32eV. While the bilayer TES showed a transition temperature of around 320 mK, the four-layer TES achieved a significantly lower value of 179 mK. Moreover, the energy collection efficiency exhibits no dependence on incident photon wavelengths, resulting in an average value of 97.4 $pm$ 1.0% over all measured data points, compared with approximately 80% for the bilayer TES. These results demonstrate that multilayer TES structures with different Debye temperatures can effectively reduce the transition temperature and confine phonons, thereby improving energy resolution.
{"title":"High Energy Collection Efficiency in a Ti/Au/Ti/Au Four-Layer Transition Edge Sensor","authors":"Takeshi Jodoi;Tetsuya Tsuruta;Takahiro Kikuchi;Nao Kominato;Koki Shirota;Daiji Fukuda","doi":"10.1109/TASC.2026.3656513","DOIUrl":"https://doi.org/10.1109/TASC.2026.3656513","url":null,"abstract":"A superconducting transition edge sensor (TES), a type of photon-number-resolving detector, is essential for quantum information applications that utilize highly nonclassical quantum states. For these applications, TES devices must simultaneously achieve high detection efficiency and high energy resolution. Matching the mode field diameter of optical fibers requires a sufficiently large sensitive area, which introduces an alignment tolerance. However, the increased heat capacity associated with a larger area degrades the energy resolution and consequently reduces the accuracy of the photon-number discrimination. Thus, developing a TES with both a large sensitive area and high energy resolution remains highly challenging. To address this issue, we developed a Ti/Au/Ti/Au four-layer structure TES. Theoretically, stacking metal materials with different Debye temperatures confines high-energy phonon within the TES. This suppression of high-energy phonon loss during energy down-conversion improves the energy collection efficiency, thereby enhancing the energy resolution. Furthermore, lowering the transition temperature through the proximity effect provides additional improvement. Consequently, we evaluated the enhancement of energy resolution resulting from phonon confinement and the reduction in transition temperature. As a result, in contrast to conventional Ti/Au bilayer TESs, the four-layer TES with a size of 21 <inline-formula><tex-math>$mathrm{mu }$</tex-math></inline-formula>m × 21 <inline-formula><tex-math>$mathrm{mu }$</tex-math></inline-formula>m exhibited photon-number-resolving ability at 1550 nm, achieving an energy resolution of 0.32eV. While the bilayer TES showed a transition temperature of around 320 mK, the four-layer TES achieved a significantly lower value of 179 mK. Moreover, the energy collection efficiency exhibits no dependence on incident photon wavelengths, resulting in an average value of 97.4 <inline-formula><tex-math>$pm$</tex-math></inline-formula> 1.0% over all measured data points, compared with approximately 80% for the bilayer TES. These results demonstrate that multilayer TES structures with different Debye temperatures can effectively reduce the transition temperature and confine phonons, thereby improving energy resolution.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A smart-insulation (SI) approach employing a metal–insulator transition (MIT) material has been investigated for improving the thermal stability and charging characteristics of REBCO coils. In this study, we investigated a coating method for REBCO tapes using a material (Pr0.8Sm0.2)0.6Ca0.4CoO3 (PSCCO) which exhibits a MIT around 74 K. PSCCO powder, synthesized by the sol–gel method and then ball-milled, was dispersed in N-methyl-2-pyrrolidone (NMP) to form a slurry, which was subsequently coated onto the REBCO tape. The contact resistivity (ρct) between REBCO tapes was measured from 10 K to 270 K under uniaxial pressures. The ρct decreased monotonically from 1.9 × 108 μΩ·cm2 at 10 K to 7.0 × 103 μΩ·cm2 at 270 K. However, the ρct did not show a sharp MIT-like transition as observed in bulk PSCCO. Magnetization measurements confirmed that the transition became significantly broadened in the coated layer. Finally, the temperature rise of a coil employing the PSCCO coating was estimated based on the previous reported theory, suggesting that a temperature increase up to around 90 K can be expected during magnet operation. These results suggest that PSCCO is a promising turn-to-turn insulation material for realizing SI coils.
{"title":"Contact Resistivity Between REBCO Tapes With (Pr0.8Sm0.2)0.6Ca0.4CoO3 Smart-Insulation Layer","authors":"Kyosuke Sakurai;Yuji Tsuchiya;Masahiro Tahashi;Hideo Goto;Satoshi Awaji","doi":"10.1109/TASC.2026.3655248","DOIUrl":"https://doi.org/10.1109/TASC.2026.3655248","url":null,"abstract":"A smart-insulation (SI) approach employing a metal–insulator transition (MIT) material has been investigated for improving the thermal stability and charging characteristics of REBCO coils. In this study, we investigated a coating method for REBCO tapes using a material (Pr<sub>0.8</sub>Sm<sub>0.2</sub>)<sub>0.6</sub>Ca<sub>0.4</sub>CoO<sub>3</sub> (PSCCO) which exhibits a MIT around 74 K. PSCCO powder, synthesized by the sol–gel method and then ball-milled, was dispersed in N-methyl-2-pyrrolidone (NMP) to form a slurry, which was subsequently coated onto the REBCO tape. The contact resistivity (<italic>ρ</i><sub>ct</sub>) between REBCO tapes was measured from 10 K to 270 K under uniaxial pressures. The <italic>ρ</i><sub>ct</sub> decreased monotonically from 1.9 × 10<sup>8</sup> μΩ·cm<sup>2</sup> at 10 K to 7.0 × 10<sup>3</sup> μΩ·cm<sup>2</sup> at 270 K. However, the <italic>ρ</i><sub>ct</sub> did not show a sharp MIT-like transition as observed in bulk PSCCO. Magnetization measurements confirmed that the transition became significantly broadened in the coated layer. Finally, the temperature rise of a coil employing the PSCCO coating was estimated based on the previous reported theory, suggesting that a temperature increase up to around 90 K can be expected during magnet operation. These results suggest that PSCCO is a promising turn-to-turn insulation material for realizing SI coils.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-19DOI: 10.1109/TASC.2026.3652669
Timo Muscheid;Daniel Crovo;Robert Gartmann;Eduardo Gerlein;Oliver Sander;Sebastian Kempf;Luis E. Ardila-Perez
Simultaneous readout of large-scale cryogenic detector arrays relies on multiplexing schemes such as frequency-division multiplexing (FDM) with microwave superconducting quantum interference device (SQUID) multiplexers and highly customized readout electronics. In traditional detector systems, where mixed-signal application-specific integrated circuit (ASIC)s are used in detector front ends and typically provide a digital interface, hardware-in-the-loop (HIL) testing can be readily implemented by reusing the existing digital logic of the front end for emulation purposes. Such straightforward emulation is not possible for FDM low-temperature detectors, where the sensor signal is encoded in a high-frequency microwave carrier via a two-stage modulation scheme depending on the cryogenic resonators and the SQUID response. To address this challenge, we present CryoDE, a digital cryogenic detector emulator for microwave SQUID multiplexed detector systems. CryoDE generates the encoded detector signals, including realistic pulse responses, enabling full HIL testing of the room temperature data acquisition (DAQ) system without requiring the cryogenic hardware. This resource-efficient detector twin integrates seamlessly into the field-programmable-gate-array (FPGA) firmware of existing DAQ systems and allows experiment-specific adjustment of detector signal parameters. We describe the internal architecture and capabilities of CryoDE within our custom HIL framework and demonstrate its use in evaluating the performance of real-time signal processing firmware optimized for different microwave SQUID multiplexed cryogenic detector experiments.
{"title":"CryoDE: A Digital Cryogenic Detector Emulator for Microwave SQUID Multiplexed Systems","authors":"Timo Muscheid;Daniel Crovo;Robert Gartmann;Eduardo Gerlein;Oliver Sander;Sebastian Kempf;Luis E. Ardila-Perez","doi":"10.1109/TASC.2026.3652669","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652669","url":null,"abstract":"Simultaneous readout of large-scale cryogenic detector arrays relies on multiplexing schemes such as frequency-division multiplexing (FDM) with microwave superconducting quantum interference device (SQUID) multiplexers and highly customized readout electronics. In traditional detector systems, where mixed-signal application-specific integrated circuit (ASIC)s are used in detector front ends and typically provide a digital interface, hardware-in-the-loop (HIL) testing can be readily implemented by reusing the existing digital logic of the front end for emulation purposes. Such straightforward emulation is not possible for FDM low-temperature detectors, where the sensor signal is encoded in a high-frequency microwave carrier via a two-stage modulation scheme depending on the cryogenic resonators and the SQUID response. To address this challenge, we present CryoDE, a digital cryogenic detector emulator for microwave SQUID multiplexed detector systems. CryoDE generates the encoded detector signals, including realistic pulse responses, enabling full HIL testing of the room temperature data acquisition (DAQ) system without requiring the cryogenic hardware. This resource-efficient detector twin integrates seamlessly into the field-programmable-gate-array (FPGA) firmware of existing DAQ systems and allows experiment-specific adjustment of detector signal parameters. We describe the internal architecture and capabilities of CryoDE within our custom HIL framework and demonstrate its use in evaluating the performance of real-time signal processing firmware optimized for different microwave SQUID multiplexed cryogenic detector experiments.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In a recently developed multilayer (ML) scheme, two or more 10-nm thick Ca0.3Y0.7Ba2Cu3O7-x spacers were inserted into BaZrO3-doped YBa2Cu3O7-x (BZO/YBCO) films to enable dynamic diffusion of Ca ions from the spacers to BZO/YBCO layers. In these ML BZO/YBCO nanocomposite films, significantly enhanced pinning has been attributed to Ca/Cu substitution on the Cu-O planes of YBCO, leading to reduced lattice mismatch and hence defects at the BZO/YBCO interface. In this work, we further probe the Ca diffusion in the five-layer ML films by varying the thickness of the two Ca0.3Y0.7Ba2Cu3O7-x spacers in the range of 1 nm-10 nm and also the thickness of the three BZO/YBCO layers in the range of 50–330 nm. Ca diffusion has been found highly effective if the spacer layer thickness exceeds 2 nm and can diffuse through large BZO/YBCO thicknesses up to 330 nm (total film thickness ∼ 1 µm) along the BZO/YBCO interface. The critical current density exhibits enhanced and almost thickness-independent trends in the ML BZO/YBCO nanocomposite films. Significantly enhanced pinning is illustrated in up to 5 folds enhancement of Jc at 65 K and 9.0 T. At lower temperatures, the enhanced pinning extends to a broad range of the orientations of magnetic field (B). At 20 K and 9.0 T, the Ic is up to 654 A/cm-width at B//c, which is close to 753 A/cm-width at B//ab due to the intrinsic pinning, has been achieved. This result suggests that the ML scheme provides an interesting approach to improve pinning in nanocomposite films.
{"title":"Achieving High and Isotropic Pinning in Multilayer BaZrO3/YBa2Cu3O7-x Films","authors":"Aafiya;Victor Ogunjimi;Mary Ann Sebastian;Mohan Panth;Benson Tsai;Abhijeet Chowdhury;Jialong Huang;Timothy Haugan;Haiyan Wang;Judy Wu","doi":"10.1109/TASC.2026.3651418","DOIUrl":"https://doi.org/10.1109/TASC.2026.3651418","url":null,"abstract":"In a recently developed multilayer (ML) scheme, two or more 10-nm thick Ca<sub>0.3</sub>Y<sub>0.7</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> spacers were inserted into BaZrO<sub>3</sub>-doped YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> (BZO/YBCO) films to enable dynamic diffusion of Ca ions from the spacers to BZO/YBCO layers. In these ML BZO/YBCO nanocomposite films, significantly enhanced pinning has been attributed to Ca/Cu substitution on the Cu-O planes of YBCO, leading to reduced lattice mismatch and hence defects at the BZO/YBCO interface. In this work, we further probe the Ca diffusion in the five-layer ML films by varying the thickness of the two Ca<sub>0.3</sub>Y<sub>0.7</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> spacers in the range of 1 nm-10 nm and also the thickness of the three BZO/YBCO layers in the range of 50–330 nm. Ca diffusion has been found highly effective if the spacer layer thickness exceeds 2 nm and can diffuse through large BZO/YBCO thicknesses up to 330 nm (total film thickness ∼ 1 µm) along the BZO/YBCO interface. The critical current density exhibits enhanced and almost thickness-independent trends in the ML BZO/YBCO nanocomposite films. Significantly enhanced pinning is illustrated in up to 5 folds enhancement of <italic>J</i><sub>c</sub> at 65 K and 9.0 T. At lower temperatures, the enhanced pinning extends to a broad range of the orientations of magnetic field (B). At 20 K and 9.0 T, the <italic>I<sub>c</sub></i> is up to 654 A/cm-width at B//c, which is close to 753 A/cm-width at B//ab due to the intrinsic pinning, has been achieved. This result suggests that the ML scheme provides an interesting approach to improve pinning in nanocomposite films.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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