Physical Review Accelerators and Beams最新文献

{"title":"Impact of beam coupling impedance on crab cavity noise induced emittance growth","authors":"N. Triantafyllou, F. Antoniou, H. Bartosik, P. Baudrenghien, X. Buffat, R. Calaga, Y. Papaphilippou, T. Mastoridis, A. Wolski","doi":"10.1103/physrevaccelbeams.27.071001","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.071001","url":null,"abstract":"Crab cavities will be deployed as a part of the High Luminosity Large Hadron Collider (HL-LHC) upgrade to mitigate the luminosity reduction induced by the crossing angle at the main experiments (ATLAS and CMS). Two prototype crab cavities have been installed in the CERN Super Proton Synchrotron (SPS) in 2018 for studies with proton beams. An issue of concern is the transverse emittance growth induced by noise in the crab cavity radio frequency (rf) system, which is anticipated to limit the performance of the HL-LHC. In measurements conducted in the SPS in 2018, the crab cavity noise-induced emittance growth was measured to be a factor of 4 lower than predicted from the existing analytical models. In this paper, it is shown that the observed discrepancy is explained by damping effects from the beam coupling impedance, which were not included in the models up to now. Using the van Kampen mode approach, a new theory is developed, suggesting that the impedance can separate the coherent tune from the incoherent spectrum leading to an effective reduction of the crab cavity rf noise-induced emittance growth. This mechanism is validated in tracking simulations using the SPS impedance model as well as in dedicated experimental measurements conducted in the SPS in 2022. The implications for the HL-LHC project are discussed.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141570976","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}

{"title":"5D tomographic phase-space reconstruction of particle bunches","authors":"S. Jaster-Merz, R. W. Assmann, R. Brinkmann, F. Burkart, W. Hillert, M. Stanitzki, T. Vinatier","doi":"10.1103/physrevaccelbeams.27.072801","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.072801","url":null,"abstract":"We propose a new beam diagnostics method to reconstruct the phase space of charged particle bunches in five dimensions, which consist of the horizontal and vertical positions and divergences as well as the time axis. This is achieved by combining a quadrupole-based transverse phase-space tomography with the adjustable streaking angle of a polarizable X-band transverse deflection structure. We demonstrate with detailed simulations that the method is able to reconstruct various complex phase-space distributions and that the quality of the reconstruction depends on the number of input projections. This method allows for the identification and visualization of previously unnoticed detailed features in the phase-space distribution and can thereby be used as a tool toward improving the performance of particle accelerators or performing more accurate simulation studies.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553072","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}

{"title":"Beam physics studies for a high charge and high beam quality laser-plasma accelerator","authors":"Samuel Marini, Damien F. G. Minenna, Francesco Massimo, Laury Batista, Vittorio Bencini, Antoine Chancé, Nicolas Chauvin, Steffen Doebert, John Farmer, Edda Gschwendtner, Ioaquin Moulanier, Patric Muggli, Didier Uriot, Brigitte Cros, Phu Anh Phi Nghiem","doi":"10.1103/physrevaccelbeams.27.063401","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.063401","url":null,"abstract":"Electron acceleration by laser-plasma techniques is approaching maturity and is getting ready for the construction of particle accelerators with dedicated applications. We present a general methodology showing how beam physics studies can be used to achieve a specific parameter set in a laser-plasma accelerator. Laser systems, plasma targets, and magnetic component properties are designed to optimize the electron beam so as to achieve the required performances. Beam physics in its full 6D phase space is studied from electron injection to beam delivery to the end user, through the plasma acceleration stage and transport line. As each beam parameter can only be modified by specific electric/magnetic field configurations, it is crucial to assign from the beginning specific roles to given accelerator sections in obtaining given beam parameters. These beam physics considerations were successfully applied to the design of a plasma-based electron injector for the AWAKE Run2 experiment. Electron beam parameters were calculated using a global simulation, achieving simultaneously unprecedented high charge (100 pC) and high quality (micrometric beam emittance and size).","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553266","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}

{"title":"Energy deposition studies for the Upgrade II of LHCb at the CERN Large Hadron Collider","authors":"Alessia Ciccotelli, Robert B. Appleby, Francesco Cerutti, Kevin Buffet, Francois Butin, Gloria Corti, Luigi Salvatore Esposito, Ruben Garcia Alia, Matthias Karacson, Giuseppe Lerner, Maud Wehrle, Daniel Prelipcean","doi":"10.1103/physrevaccelbeams.27.061003","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.061003","url":null,"abstract":"The Upgrade II of the Large Hadron Collider beauty (LHCb) experiment is proposed to be installed during the CERN Long Shutdown 4, aiming to operate LHCb at <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>1.5</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>34</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>cm</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mtext> </mtext><msup><mrow><mi mathvariant=\"normal\">s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math> that is 75 times its design luminosity [1] and reaching an integrated luminosity of about <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>400</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math> by the end of the High Luminosity LHC era. This increase of the data sample at LHCb is an unprecedented opportunity for heavy flavor physics measurements. A first upgrade of LHCb (Upgrade I), completed in 2022, has already implemented important changes of the LHCb detector and, for the Upgrade II, further detector improvements of the tracking system, the particle identification system and the online and trigger infrastructure are being considered. Such a luminosity increase will have an impact not only on the LHCb detector but also on the LHC magnets, cryogenics, and electronic equipment placed in the insertion region 8. In fact, the LHCb experiment was conceived to work at a much lower luminosity than ATLAS and CMS, implying minor requirements for protection of the LHC elements from the collision debris, and therefore, a different layout around the interaction point. The Upgrade I has already implied the installation of an absorber for the neutral particle debris (TANB). However, the luminosity target proposed for this second upgrade requires to review the layout of the entire insertion region in order to ensure safe operation of the LHC magnets and to mitigate the risk of failure of the electronic devices. The objective of this paper is to provide an overview of the implications of the Upgrade II of LHCb in the experimental cavern and in the tunnel with a focus on the LHCb detector, electronic devices, and accelerator magnets. This proves that the Upgrade II luminosity goal can be sustained with the implementation of protection systems for magnets and electronics. The electronics placed in the experimental areas and in the cavern needs to be protected to mitigate a single event effect risk, which may imply recurring downtime of the LHC. On the other hand, protection for the first quadrupole of the final focus triplet and for the separation dipole are needed to prevent their quench and to reach the desired lifetime. Moreover, the normal-conducting compensators require the installation of shielding to limit their head coil degradation.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553280","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}

{"title":"3D small-gain formula allowing strong focusing and harmonic lasing for a ring-based x-ray free electron laser oscillator","authors":"Li Hua Yu, Victor Smaluk, Timur Shaftan, Ganesh Tiwari, Xi Yang","doi":"10.1103/physrevaccelbeams.27.060702","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.060702","url":null,"abstract":"We present a detailed derivation of a formula for the small-gain calculation for an x-ray free electron laser oscillator (XFELO) based on a medium-energy (3–4 GeV) storage ring. We found harmonic lasing and strong focusing are essential for this beam energy range. Taking the small-signal low-gain formula developed by Kim and his colleagues, we modified it in such a way that the gain can be calculated without the “no focusing approximation,” and a strong focusing can be applied, as well as harmonic lasing. In this formula, the gain is represented as a product of two factors with one of them depending only on the harmonic number, undulator period, and gap. Using this factor, we show that it is favorable to use harmonic lasing to achieve hard x-ray FEL working in the small-signal low-gain regime with the medium-energy electron beam. Our formula also allows FEL optimization by varying the vertical gradient of the undulator, the vertical dispersion, and the horizontal and vertical focusing, independently. As an example, we applied this formula to study the feasibility of an XFELO option for the National Synchrotron Light Source II (NSLS-II) upgrade. Since a quite high peak current is required for the FEL, collective effects of beam dynamics in medium-energy synchrotrons significantly affect the electron beam parameters. We carried out a multiparameter optimization taking collective effects into account. Note, even though our example is for a ring-based XFELO at 3 to 4 GeV, the formula and, in particular, the approach developed here may be applied to other types of FELs.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553071","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}

{"title":"Attosecond two-color x-ray free-electron lasers with dual chirp-taper configuration and bunching inheritance","authors":"Hao Sun, Xiaofan Wang, Weiqing Zhang","doi":"10.1103/physrevaccelbeams.27.060701","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.060701","url":null,"abstract":"Attosecond x-ray pulses play a crucial role in the study of ultrafast phenomena occurring within inner and valence electrons. To achieve attosecond time-resolution studies and gain control over electronic wave functions, it is crucial to develop techniques capable of generating and synchronizing two-color x-ray pulses at the attosecond scale. In this paper, we present a novel approach for generating attosecond pulse pairs using a dual chirp-taper free-electron laser with bunching inheritance. An electron beam with a sinusoidal energy chirp, introduced by the external laser, passes through the main undulator and afterburner, both with tapers. Two-color x-ray pulses are generated from the main undulator and the afterburner, respectively, with temporal separations of several femtoseconds and energy separations of tens of electron volts. Notably, the afterburner is much shorter than the main undulator due to the bunching inheritance, which reduces the distance between two source points and alleviates the beamline focusing requirements of the two-color pulses. A comprehensive stability analysis is conducted in this paper, considering the individual effects of shot noise from self-amplified spontaneous emission and carrier-envelope phase jitter of the few-cycle laser. The results show that the radiation from the afterburner exhibits excellent stability in the proposed scheme, which is beneficial for x-ray pump-probe experiments. The proposed scheme opens up new possibilities for attosecond science enabled by x-ray attosecond pump-probe techniques and coherent control of ultrafast electronic wave packets in quantum systems.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553073","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}

{"title":"Machine-learning-based pressure-anomaly detection system for SuperKEKB accelerator","authors":"Yusuke Suetsugu","doi":"10.1103/physrevaccelbeams.27.063201","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.063201","url":null,"abstract":"This study developed a pressure-anomaly detection system utilizing machine learning for the vacuum system of the SuperKEKB accelerator. The system identified abnormal pressure behaviors among approximately 600 vacuum gauges before triggering the conventional alarm system, facilitating the early implementation of countermeasures and minimizing potential vacuum issues. By comparing the recent pressure behaviors of each vacuum gauge with the previous behaviors, the program detected anomalies using the decision boundary of a feed-forward neural network previously trained on actual abnormal behaviors. Realistic regression models for pressure data curves enabled a reasonable prediction of the causes of anomalies. The program, implemented in python, has been operational since April 2024. Although based on a rudimentary machine-learning concept, the developed anomaly detection system is beneficial for ensuring the stable operation of large-scale machines, including accelerators, and is helpful in designing systems for fault detection.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553278","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}

{"title":"Acceleration of uranium beam to record power of 10.4 kW and observation of new isotopes at Facility for Rare Isotope Beams","authors":"P. N. Ostroumovet al.","doi":"10.1103/physrevaccelbeams.27.060101","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.060101","url":null,"abstract":"The Facility for Rare Isotope Beams (FRIB) is a major nuclear physics facility for research with fast, stopped, and reaccelerated beams that was successfully commissioned in May 2022. A key capability of FRIB is the production of an acceleration of the uranium beam, but this capability requires the facility to work at the design limits of the lowest charge-to-mass ratio and the highest power density on the beam intercepting devices. This paper presents techniques for overcoming the significant challenges in accelerating the uranium beam, culminating in the demonstration of 10.4 kW on target, and the discovery of three new isotopes. The high-power uranium beam enabled us to produce and identify <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi mathvariant=\"normal\">G</mi><mprescripts></mprescripts><none></none><mn>88</mn></mmultiscripts><mi mathvariant=\"normal\">a</mi></mrow></math>, <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi mathvariant=\"normal\">A</mi><mprescripts></mprescripts><none></none><mn>93</mn></mmultiscripts><mi mathvariant=\"normal\">s</mi></mrow></math>, and <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi mathvariant=\"normal\">S</mi><mprescripts></mprescripts><none></none><mn>96</mn></mmultiscripts><mi mathvariant=\"normal\">e</mi></mrow></math>, within the first 24 h of operation. The successful uranium operation at FRIB sets a new record for accelerated uranium beam power above 10 kW and opens a new avenue of research with rare isotopes.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553267","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}

{"title":"Enhanced beam-beam modeling to include longitudinal variation during weak-strong simulation","authors":"Derong Xu, Vasiliy S. Morozov, David Sagan, Yue Hao, Yun Luo","doi":"10.1103/physrevaccelbeams.27.061002","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.061002","url":null,"abstract":"Beam-beam interactions pose substantial challenges in the design and operation of circular colliders, significantly affecting their performance. In particular, the weak-strong simulation approach is pivotal for investigating single-particle dynamics during the collider design phase. This paper evaluates the limitations of existing models in weak-strong simulations, noting that while they accurately account for energy changes due to slingshot effects, they fail to incorporate longitudinal coordinate changes (<math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>z</mi></math> variation). To address this gap, we introduce two novel transformations that enhance Hirata’s original framework by including both <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>z</mi></math> variation and slingshot effect-induced energy changes. Through rigorous mathematical analysis and extensive weak-strong simulation studies, we validate the efficacy of these enhancements in achieving a more precise simulation of beam-beam interactions. Our results reveal that although <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>z</mi></math> variation constitutes a higher-order effect and does not substantially affect the emittance growth rate within the specific design parameters of the Electron-Ion Collider, the refined model offers improved accuracy, particularly in scenarios involving the interaction between beam-beam effects and other random diffusion processes, as well as in simulations incorporating realistic lattice models.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553074","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}

{"title":"Field, frequency, and temperature dependencies of the surface resistance of nitrogen diffused niobium superconducting radio frequency cavities","authors":"P. Dhakal, B. D. Khanal, A. Gurevich, G. Ciovati","doi":"10.1103/physrevaccelbeams.27.062001","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.062001","url":null,"abstract":"We investigate the rf performance of several single-cell superconducting radio-frequency cavities subjected to low temperature heat treatment in nitrogen environment. The cavities were treated at temperature <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>120</mn><mi>–</mi><mn>165</mn><mtext> </mtext><mi>°</mi><mi mathvariant=\"normal\">C</mi></mrow></math> for an extended period of time (24–48 h) either in high vacuum or in a low partial pressure of ultrapure nitrogen. The improvement in <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Q</mi><mn>0</mn></msub></math> with a <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Q</mi></math> rise was observed when nitrogen gas was injected at <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mo>∼</mo><mn>300</mn><mtext> </mtext><mi>°</mi><mi mathvariant=\"normal\">C</mi></mrow></math> during the cavity cooldown from <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>800</mn><mtext> </mtext><mi>°</mi><mi mathvariant=\"normal\">C</mi></mrow></math> and held at <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>165</mn><mtext> </mtext><mi>°</mi><mi mathvariant=\"normal\">C</mi></mrow></math>, without any degradation in accelerating gradient over the baseline performance. The treatment was applied to several elliptical cavities with frequency ranging from 0.75 to 3.0 GHz, showing an improved quality factor as a result of low temperature nitrogen treatments. The <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Q</mi></math> rise feature is similar to that achieved by nitrogen alloying Nb cavities at higher temperature, followed by material removal by electropolishing. The surface modification was confirmed by the change in electronic mean free path and tuned with the temperature and duration of heat treatment. The decrease of the temperature-dependent surface resistance with increasing rf field, resulting in a <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Q</mi></math> rise, becomes stronger with increasing frequency and decreasing temperature. The data suggest a crossover frequency of <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>∼</mo><mn>0.95</mn><mtext> </mtext><mtext> </mtext><mi>GHz</mi></math> above that the <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Q</mi></math> rise phenomenon occurs at 2 K. Some of these results can be explained qualitatively with an existing model of intrinsic field-dependence of the surface resistance with both equilibrium and nonequilibrium quasiparticle distribution functions. The change in the <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Q</mi></math> slope below 0.95 GHz may result from masking contribution of trapped magnetic flux to the residual surface resistance.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553174","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}