Pub Date : 2024-06-21DOI: 10.1103/physrevaccelbeams.27.060702
Li Hua Yu, Victor Smaluk, Timur Shaftan, Ganesh Tiwari, Xi Yang
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.
我们详细推导了基于中等能量（3-4 GeV）存储环的 X 射线自由电子激光振荡器（XFELO）的小增益计算公式。我们发现谐波激光和强聚焦对这一光束能量范围至关重要。利用 Kim 及其同事开发的小信号低增益公式，我们对其进行了修改，使其在计算增益时可以不使用 "无聚焦近似"，并且可以应用强聚焦以及谐波激光。在这个公式中，增益表示为两个系数的乘积，其中一个系数只取决于谐波数、起伏周期和间隙。利用这个系数，我们证明了利用谐波激光实现硬 X 射线 FEL 在小信号低增益状态下与中等能量电子束一起工作是有利的。我们的计算公式还允许通过独立改变减压器的垂直梯度、垂直色散以及水平和垂直聚焦来优化 FEL。举例来说，我们应用该公式研究了美国国家同步辐射光源二期（NSLS-II）升级的 XFELO 方案的可行性。由于 FEL 需要相当高的峰值电流，因此中能同步加速器中光束动态的集体效应会对电子束参数产生重大影响。考虑到集体效应，我们进行了多参数优化。需要注意的是，尽管我们的例子是基于环的 3 至 4 GeV XFELO，但该公式，尤其是此处开发的方法可用于其他类型的 FEL。
{"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":"35 1","pages":""},"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}
Pub Date : 2024-06-20DOI: 10.1103/physrevaccelbeams.27.060701
Hao Sun, Xiaofan Wang, Weiqing Zhang
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.
阿秒 X 射线脉冲在研究内价电子和价电子内部发生的超快现象中发挥着至关重要的作用。为了实现阿秒时间分辨率研究并获得对电子波函数的控制，开发能够在阿秒尺度上产生和同步双色 X 射线脉冲的技术至关重要。在本文中，我们介绍了一种利用具有束集继承性的双啁啾锥自由电子激光器产生阿秒脉冲对的新方法。由外部激光器引入的具有正弦能量啁啾的电子束通过主起爆器和后燃器，两者都具有锥度。主减波器和后燃器分别产生双色 X 射线脉冲，时间间隔为数飞秒，能量间隔为数十电子伏特。值得注意的是，由于束流继承，后燃器比主起伏器短得多，这就缩短了两个源点之间的距离，减轻了双色脉冲对光束线聚焦的要求。本文进行了全面的稳定性分析，考虑了自放大自发辐射的射出噪声和几周期激光的载波包络相位抖动的单独影响。结果表明，在所提出的方案中，来自后燃器的辐射表现出了极佳的稳定性，这有利于 X 射线泵浦探针实验。所提出的方案为利用 X 射线阿秒泵浦探针技术进行阿秒科学研究以及量子系统中超快电子波包的相干控制开辟了新的可能性。
{"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":"58 1","pages":""},"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}
Pub Date : 2024-06-20DOI: 10.1103/physrevaccelbeams.27.063201
Yusuke Suetsugu
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.
{"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":"12 1","pages":""},"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}
Pub Date : 2024-06-17DOI: 10.1103/physrevaccelbeams.27.060101
P. N. Ostroumovet al.
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 , , and , 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.
{"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":"23 1","pages":""},"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}
Pub Date : 2024-06-17DOI: 10.1103/physrevaccelbeams.27.061002
Derong Xu, Vasiliy S. Morozov, David Sagan, Yue Hao, Yun Luo
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 ( variation). To address this gap, we introduce two novel transformations that enhance Hirata’s original framework by including both 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 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.
光束与光束之间的相互作用给环形对撞机的设计和运行带来了巨大挑战，严重影响了对撞机的性能。特别是在对撞机设计阶段，弱强模拟方法对于研究单粒子动力学至关重要。本文评估了弱-强模拟中现有模型的局限性，指出这些模型虽然准确地解释了弹弓效应引起的能量变化，但未能纳入纵向坐标变化（z 变化）。为了弥补这一不足，我们引入了两种新的变换，通过同时包含 z 变化和弹弓效应引起的能量变化来增强平田的原始框架。通过严格的数学分析和广泛的弱-强模拟研究，我们验证了这些增强方法在更精确地模拟光束-光束相互作用方面的功效。我们的研究结果表明，尽管z 变化是一种高阶效应，在电子离子对撞机的特定设计参数范围内并不会对辐照增长率产生实质性影响，但改进后的模型却提高了精确度，尤其是在涉及束-束效应与其他随机扩散过程相互作用的情况下，以及在包含现实晶格模型的模拟中。
{"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":"11 1","pages":""},"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}
Pub Date : 2024-06-12DOI: 10.1103/physrevaccelbeams.27.062001
P. Dhakal, B. D. Khanal, A. Gurevich, G. Ciovati
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 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 with a rise was observed when nitrogen gas was injected at during the cavity cooldown from and held at , 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 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 rise, becomes stronger with increasing frequency and decreasing temperature. The data suggest a crossover frequency of above that the 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 slope below 0.95 GHz may result from masking contribution of trapped magnetic flux to the residual surface resistance.
{"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":"365 1","pages":""},"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}
Pub Date : 2024-06-12DOI: 10.1103/physrevaccelbeams.27.064403
M. Zampetakis, F. Antoniou, F. Asvesta, H. Bartosik, Y. Papaphilippou
Future ultralow emittance rings for colliders require extremely high beam brightness and can thus be limited by collective effects. In this paper, the interplay of effects such as synchrotron radiation, intrabeam scattering (IBS), and space charge in the vicinity of excited betatron resonances is assessed. In this respect, two algorithms were developed to simulate IBS and synchrotron radiation effects and integrated in the pyorbit tracking code, to be combined with its widely used space charge module. The impact of these effects on the achievable beam parameters of the Compact Linear Collider (CLIC) damping rings was studied, showing that synchrotron radiation damping mitigates the adverse effects of IBS and space charge induced resonance crossing. The studies include also a full dynamic simulation of the CLIC damping ring cycle starting from the injection beam parameters. It is demonstrated that a careful working point choice is necessary, in order to accommodate the transition from detuning induced by lattice nonlinearities to space-charge dominated detuning and thereby avoid excessive losses and emittance growth generated in the vicinity of strong resonances.
{"title":"Interplay of space charge, intrabeam scattering, and synchrotron radiation in the Compact Linear Collider damping rings","authors":"M. Zampetakis, F. Antoniou, F. Asvesta, H. Bartosik, Y. Papaphilippou","doi":"10.1103/physrevaccelbeams.27.064403","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.064403","url":null,"abstract":"Future ultralow emittance rings for <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>e</mi><mo>−</mo></msup><mo>/</mo><msup><mi>e</mi><mo>+</mo></msup></math> colliders require extremely high beam brightness and can thus be limited by collective effects. In this paper, the interplay of effects such as synchrotron radiation, intrabeam scattering (IBS), and space charge in the vicinity of excited betatron resonances is assessed. In this respect, two algorithms were developed to simulate IBS and synchrotron radiation effects and integrated in the <span>p</span>y<span>orbit</span> tracking code, to be combined with its widely used space charge module. The impact of these effects on the achievable beam parameters of the Compact Linear Collider (CLIC) damping rings was studied, showing that synchrotron radiation damping mitigates the adverse effects of IBS and space charge induced resonance crossing. The studies include also a full dynamic simulation of the CLIC damping ring cycle starting from the injection beam parameters. It is demonstrated that a careful working point choice is necessary, in order to accommodate the transition from detuning induced by lattice nonlinearities to space-charge dominated detuning and thereby avoid excessive losses and emittance growth generated in the vicinity of strong resonances.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"52 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553075","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 : 2024-06-11DOI: 10.1103/physrevaccelbeams.27.061601
Minghao Song, Timur Shaftan
Light sources worldwide have experienced rapid growth in the last decades, pushing toward higher brightness with lower emittance to meet growing demands from the user community. The quest for higher brightness motivates the development of low-emittance ring lattices. At this point, all fourth-generation storage ring light sources employ variations of the multibend achromat (MBA) lattice. In this paper, we discuss an extension of this approach, known as complex bend achromat lattice in relation to the future NSLS-II upgrade. A detailed approach for the lattice design will be described and the developed lattice will be presented. The advantages of using our complex bend approach are evident in reaching a natural emittance as low as 23 pm at a beam energy of 3 GeV, providing a straight section of 8.4 m for long insertion devices, and acquiring a ratio of about 50% of free space with respect to the ring circumference. The design includes the use of permanent magnets largely reducing the need for power supplies. Our new approach provides an extension to the MBA concept for the next-generation light source lattice design.
{"title":"Design study of a low emittance complex bend achromat lattice","authors":"Minghao Song, Timur Shaftan","doi":"10.1103/physrevaccelbeams.27.061601","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.061601","url":null,"abstract":"Light sources worldwide have experienced rapid growth in the last decades, pushing toward higher brightness with lower emittance to meet growing demands from the user community. The quest for higher brightness motivates the development of low-emittance ring lattices. At this point, all fourth-generation storage ring light sources employ variations of the multibend achromat (MBA) lattice. In this paper, we discuss an extension of this approach, known as complex bend achromat lattice in relation to the future NSLS-II upgrade. A detailed approach for the lattice design will be described and the developed lattice will be presented. The advantages of using our complex bend approach are evident in reaching a natural emittance as low as 23 pm at a beam energy of 3 GeV, providing a straight section of 8.4 m for long insertion devices, and acquiring a ratio of about 50% of free space with respect to the ring circumference. The design includes the use of permanent magnets largely reducing the need for power supplies. Our new approach provides an extension to the MBA concept for the next-generation light source lattice design.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553176","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 high-energy electron-positron collider has been widely recognized by the particle physics community to be the next crucial step for detailed studies of the Higgs boson and other fundamental particles and processes. Several proposals for such colliders, either linear or circular, are currently under evaluation. Any such collider will be required to reach high lumimosities, in order to collect enough data at a reasonable time scale, while at the same time coping with high rates of background particles produced from beam-beam interactions during the collisions. In this paper, we analyze the luminosity and beam-beam interaction characteristics of the Cool Copper Collider () and perform a comparison with other linear collider proposals. We conclude that can reach the same or higher collision rates as the other proposals, without having to cope with higher beam-induced background fluxes. Thus, emerges as an attractive option for a future electron-positron collider, benefiting from the collective advancements in beam delivery and final focus system technologies developed by other linear collider initiatives.
{"title":"Luminosity and beam-induced background studies for the Cool Copper Collider","authors":"Dimitrios Ntounis, Emilio Alessandro Nanni, Caterina Vernieri","doi":"10.1103/physrevaccelbeams.27.061001","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.061001","url":null,"abstract":"A high-energy electron-positron collider has been widely recognized by the particle physics community to be the next crucial step for detailed studies of the Higgs boson and other fundamental particles and processes. Several proposals for such colliders, either linear or circular, are currently under evaluation. Any such collider will be required to reach high lumimosities, in order to collect enough data at a reasonable time scale, while at the same time coping with high rates of background particles produced from beam-beam interactions during the collisions. In this paper, we analyze the luminosity and beam-beam interaction characteristics of the Cool Copper Collider (<math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msup><mrow><mi mathvariant=\"normal\">C</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></math>) and perform a comparison with other linear collider proposals. We conclude that <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msup><mrow><mi mathvariant=\"normal\">C</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></math> can reach the same or higher collision rates as the other proposals, without having to cope with higher beam-induced background fluxes. Thus, <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msup><mrow><mi mathvariant=\"normal\">C</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></math> emerges as an attractive option for a future electron-positron collider, benefiting from the collective advancements in beam delivery and final focus system technologies developed by other linear collider initiatives.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"15 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553175","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 : 2024-06-04DOI: 10.1103/physrevaccelbeams.27.064401
M. Southerby, R. Apsimon
In this paper, a self-consistent transverse beam dynamics framework is demonstrated that incorporates acceleration into the transverse beam dynamics studies for a proton linac machine. Two focusing schemes are developed and discussed: the FODO-like scheme and the minimum aperture scheme. The FODO-like scheme is a simple scheme, requiring only one quadrupole per cavity. The scheme is analytically solved to minimize the beam size at the cavity entrance/exit and ensures a constant beam size along the lattice, with respect to adiabatic damping due to longitudinally accelerating rf cavities. The minimum aperture scheme describes the regime that matches the beam ellipse to the acceptance ellipse of a cavity, allowing for the smallest possible aperture, for a given cavity length. A simple approximation of an rf cavity map is determined to allow changes in particle energy along a lattice, and acceleration is assumed only in the longitudinal direction.
{"title":"Beam dynamics framework incorporating acceleration to define the minimum aperture in two focusing schemes for proton radiotherapy linac","authors":"M. Southerby, R. Apsimon","doi":"10.1103/physrevaccelbeams.27.064401","DOIUrl":"https://doi.org/10.1103/physrevaccelbeams.27.064401","url":null,"abstract":"In this paper, a self-consistent transverse beam dynamics framework is demonstrated that incorporates acceleration into the transverse beam dynamics studies for a proton linac machine. Two focusing schemes are developed and discussed: the FODO-like scheme and the minimum aperture scheme. The FODO-like scheme is a simple scheme, requiring only one quadrupole per cavity. The scheme is analytically solved to minimize the beam size at the cavity entrance/exit and ensures a constant beam size along the lattice, with respect to adiabatic damping due to longitudinally accelerating rf cavities. The minimum aperture scheme describes the regime that matches the beam ellipse to the acceptance ellipse of a cavity, allowing for the smallest possible aperture, for a given cavity length. A simple approximation of an rf cavity map is determined to allow changes in particle energy along a lattice, and acceleration is assumed only in the longitudinal direction.","PeriodicalId":54297,"journal":{"name":"Physical Review Accelerators and Beams","volume":"37 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141258895","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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