IPAC2021 - List of Keywords (synchrotron-radiation)

Paper	Title	Other Keywords	Page
MOPAB245	Theoretical Analysis of the Conditions for an Isochronous and CSR-Immune Triple-Bend Achromat with Stable Optics	emittance, dipole, optics, radiation	786
	C. Zhang, Y. Jiao IHEP, Beijing, People’s Republic of China C.-Y. Tsai HUST, Wuhan, People’s Republic of China
	Funding: National Natural Science Foundation of China (No. 11922512), Youth Innovation Promotion Association of Chinese Academy of Sciences (No. Y201904), National Key R&D Program of China (No. 2016YFA0401900) Transport of high-brightness beams with minimum degradation of the phase space quality is pursued in modern accelerators. For the beam transfer line which commonly consists of bending magnets, it would be desirable if the transfer line can be isochronous and coherent synchrotron radiation (CSR)-immune. For multi-pass transfer line, the achromatic cell designs with stable optics would bring great convenience. In this paper, based on the transfer matrix formalism and the CSR point-kick model, we report the detailed theoretical analysis and derive the condition for a triple-bend achromat with stable optics in which the first-order longitudinal dispersion (i.e., R56) and the CSR-induced emittance growth can be eliminated. The derived condition suggests a new way of designing the bending magnet beamline that can be applied to the free-electron laser (FEL) spreader and energy recovery linac (ERL) recirculation loop.
	Poster MOPAB245 [0.530 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB245
About •	paper received ※ 12 May 2021 paper accepted ※ 08 June 2021 issue date ※ 27 August 2021
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TUPAB255	Longitudinal Beam Dynamics and Coherent Synchrotron Radiation at cSTART	synchrotron, radiation, electron, storage-ring	2050
	M. Schwarz, E. Bründermann, D. El Khechen, B. Härer, A. Malygin, A.-S. Müller, M.J. Nasse, A.I. Papash, R. Ruprecht, J. Schäfer, M. Schuh, P. Wesolowski KIT, Karlsruhe, Germany
	The compact STorage ring for Accelerator Research and Technology (cSTART) project aims to store electron bunches of LWFA-like beams in a very large momentum acceptance storage ring. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for cSTART to benchmark and emulate laser-wakefield accelerator-like beams. In a second stage a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and Helmholtz Institute Jena (HIJ). With an energy of 50 MeV and damping times of several seconds, the electron beam does not reach equilibrium emittance. Furthermore, the critical frequency of synchrotron radiation is 53 THz and in the same order as the bunch spectrum, which implies that the entire bunch radiates coherently. We perform longitudinal particle tracking simulations to investigate the evolution of the bunch length and spectrum as well as the emitted coherent synchrotron radiation. Finally, different options for the RF system are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB255
About •	paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 29 August 2021
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TUPAB264	Shielding of CSR Wake in a Drift	impedance, shielding, radiation, wakefield	2079
	G. Stupakov SLAC, Menlo Park, California, USA
	Funding: Work supported by the Department of Energy, contract DE-AC03-76SF00515. A one-dimensional model of coherent synchrotron radiation (CSR) wakefield developed in Refs. [,] is used in computer codes for the simulation of relativistic electron beams. It includes transient effects at the entrance and exit from a bending magnet of finite length. In the ultra-relativistic limit, v=c, the exit CSR wake decays inversely proportional to the distance from the magnet end. To calculate the total energy loss of the beam one needs to integrate this wake to infinity, but the integral diverges. This means that one has to either drop the assumption of the infinite value of the Lorentz factor or take into account the shielding effect of the metal walls in the vacuum chamber. In practice, the latter effect is often dominant. In this work, we derive formulas for the CSR wake in the drift after an exit from the magnet that incorporates the shielding by two parallel metal plates. They allow computing the energy loss of different particles in the beam. E. L. Saldin, E. A. Schneidmiller, and M. V. Yurkov. NIMA v. 398, p. 373 (1997). ** G. Stupakov and P. Emma. In: Proceedings of 8th EPAC. Paris, France, 2002, p. 1479.
	Poster TUPAB264 [0.661 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB264
About •	paper received ※ 10 May 2021 paper accepted ※ 25 June 2021 issue date ※ 22 August 2021
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TUPAB318	The Beamline Safety Interlock System of Taiwan Photon Source	radiation, vacuum, photon, controls	2239
	C.F. Chang, C.Y. Chang, C.Y. Liu, H.Y. Yan NSRRC, Hsinchu, Taiwan
	The energy of synchrotron radiation generated by bremsstrahlung radiation and magnet is rather high, which may cause serious radiation damage to human body or even imperil people’s life. The beamline therefore must be equipped with radiation-protection system; in addition, the overheat of optical components exposed to synchrotron radiation will lead to the damage of optical components and devices. In consequence, the beamline should be furnished with the cooling-protection system to cool down optical components and devices. The Beamline Safety Interlock System targets at protecting the personnel and the safety of devices, limiting the radiation dose to a security value for experimental personnel or staffs exposing to radiation on the site as well as preventing beamline components from being exposed to overheat or vacuum damages to improve the effectiveness of beamline.
	Poster TUPAB318 [3.440 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB318
About •	paper received ※ 09 May 2021 paper accepted ※ 10 June 2021 issue date ※ 31 August 2021
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WEPAB002	The Interaction Region of the Electron-Ion Collider EIC	electron, radiation, synchrotron, detector	2574
	H. Witte, J. Adam, M. Anerella, E.C. Aschenauer, J.S. Berg, M. Blaskiewicz, A. Blednykh, W. Christie, J.P. Cozzolino, K.A. Drees, D.M. Gassner, K. Hamdi, C. Hetzel, H.M. Hocker, D. Holmes, A. Jentsch, A. Kiselev, P. Kovach, H. Lovelace III, Y. Luo, G.J. Mahler, A. Marone, G.T. McIntyre, C. Montag, R.B. Palmer, B. Parker, S. Peggs, S.R. Plate, V. Ptitsyn, G. Robert-Demolaize, C.E. Runyan, J. Schmalzle, K.S. Smith, S. Tepikian, P. Thieberger, J.E. Tuozzolo, F.J. Willeke, Q. Wu, Z. Zhang BNL, Upton, New York, USA B.R. Gamage, T.J. Michalski, V.S. Morozov, M.L. Stutzman, W. Wittmer JLab, Newport News, Virginia, USA M.K. Sullivan SLAC, Menlo Park, California, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. This paper presents an overview of the Interaction Region (IR) design for the planned Electron-Ion Collider (EIC) at Brookhaven National Laboratory. The IR is designed to meet the requirements of the nuclear physics community . The IR design features a ±4.5 m free space for the detector; a forward spectrometer magnet is used for the detection of hadrons scattered under small angles. The hadrons are separated from the neutrons allowing detection of neutrons up to ±4 mrad. On the rear side, the electrons are separated from photons using a weak dipole magnet for the luminosity monitor and to detect scattered electrons (e-tagger). To avoid synchrotron radiation backgrounds in the detector no strong electron bending magnet is placed within 40 m upstream of the IP. The magnet apertures on the rear side are large enough to allow synchrotron radiation to pass through the magnets. The beam pipe has been optimized to reduce the impedance; the total power loss in the central vacuum chamber is expected to be less than 90 W. To reduce risk and cost the IR is designed to employ standard NbTi superconducting magnets, which are described in a separate paper. An Assessment of U.S.-Based Electron-Ion Collider Science. (2018). Washington, D.C.: National Academies Press. https://doi.org/10.17226/25171
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB002
About •	paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 31 August 2021
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WEPAB234	Simulating Two Dimensional Coherent Synchrotron Radiation in Python	emittance, simulation, radiation, electron	3177
	W. Lou, Y. Cai, C.E. Mayes, G.R. White SLAC, Menlo Park, California, USA
	Coherent Synchrotron Radiation (CSR) in bending magnets poses an important limit for electron beams to reach high brightness in novel accelerators. While the longitudinal wakefield has been well studied in one-dimensional CSR theory and implemented in various simulation codes, transverse wakefields have received less attention. Following the recently developed two-dimensional CSR theory, we developed a Python code simulating the steady-state two-dimensional CSR effects. The computed CSR wakes have been benchmarked with theory and other simulation codes. To speed up computation speed, the code applies vectorization, parallel processing, and Numba in Python.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB234
About •	paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 20 August 2021
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WEPAB240	Increasing the Single-Bunch Instability Threshold by Bunch Splitting Due to RF Phase Modulation	synchrotron, radiation, detector, electron	3193
	J.L. Steinmann, E. Blomley, M. Brosi, E. Bründermann, A. Mochihashi, A.-S. Müller, M. Schuh, P. Schönfeldt KIT, Karlsruhe, Germany
	Funding: This work is funded by the BMBF contract number: 05K16VKA. RF phase modulation at twice the synchrotron frequency can be used to split a stored electron bunch into two or more bunchlets orbiting each other. We report on time-resolved measurements at the Karlsruhe Research Accelerator (KARA), where this bunch splitting was used to increase the threshold current of the microbunching instability, happening in the short-bunch operation mode. Turning the modulation on and off reproducibly affects the sawtooth behavior of the emitted coherent synchrotron radiation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB240
About •	paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 18 August 2021
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THXA05	A Fast Method of 2D Calculation of Coherent Synchrotron Radiation Wakefield in Relativistic Beams	radiation, electron, dipole, synchrotron	3696
	J. Tang, Z. Huang, G. Stupakov SLAC, Menlo Park, California, USA
	Coherent Synchrotron Radiation (CSR) is regarded as one of the most important reasons that limit beam brightness in modern accelerators. CSR wakefield is often computed in a 1D assuming a line charge, which can become invalid when the beam has a large transverse extension and small bunch length. On the other hand, the existing 2D or 3D codes are often computationally inefficient or incomplete. In our previous work * we developed a new model for fast computation of 2D CSR wakefield in relativistic beams with Gaussian distribution. Here we further generalize this model to achieve self-consistent computation compatible with arbitrary beam distribution and nonlinear magnetic lattice with particle tracking. These new features can enable us to perform realistic simulations and study the physics of CSR beyond 1D in electron beams with extreme short bunch length and high peak current. * J. Tang and G. Stupakov. NAPAC2019, paper WEPLS09 (2019).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA05
About •	paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 21 August 2021
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THPAB065	Experimental Verification of the Source of Excessive Helical SCU Heat Load at APS	vacuum, radiation, photon, synchrotron	3904
	V. Sajaev, J.C. Dooling, K.C. Harkay ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Immediately after the installation of the Helical superconducting undulator (HSCU) in the APS storage ring, higher than expected heating was observed in the cryogenic cooling system. Steering the electron beam orbit in the upstream dipole reduced the amount of synchrotron radiation reaching into the HSCU and allowed the device to properly cool and operate. The simplest explanation of the excessive heat load was higher than expected heat transfer from the vacuum chamber to the magnet coils. However, modeling of the synchrotron radiation interaction with the HSCU vacuum chamber showed that Compton scattering could also result in synchrotron radiation penetrating the vacuum chamber and depositing energy directly into the HSCU coils*. In this paper, we present experimental evidence that the excessive heat load of the HSCU coils is not caused by the heat transfer from the vacuum chamber but resulted from the synchrotron radiation penetrating the vacuum chamber. M. Kasa et. al., Phys. Rev. AB, v. 23 050701 (2020) ** J. Dooling et. al., IPAC 2019 Proc., THPTS093 (2019)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB065
About •	paper received ※ 12 May 2021 paper accepted ※ 02 September 2021 issue date ※ 16 August 2021
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THPAB079	Design Study on Beam Size Measurement System Using SR Interferometry for Low Beam Current	electron, synchrotron, radiation, storage-ring	3949
	W. Li, P. Liu, Y.K. Wu, J. Yan FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. To enable reliable measurements of the small vertical size of the electron beam in the Duke storage ring, a measurement system is being developed using synchrotron radiation interferometry (SRI). By relating the transverse beam size to the transverse spatial coherence of synchrotron radiation from a dipole magnet according to the Van Cittert-Zernike theorem, the transverse beam size can be inferred by recording and fitting the interference fringe as a function of the characteristic features of the interference filter used. In this paper, we describe the preliminary design of such a measurement system and present design considerations to make it possible to measure the electron beam vertical size for a wide range of electron beam energies and currents. Especially this system will be optimized to measure the electron beam size for low current operation down to 50 to 100~μA. This beam size measurement system will be used as an important beam diagnostic for the intrabeam scattering research at the Duke storage ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB079
About •	paper received ※ 27 May 2021 paper accepted ※ 12 July 2021 issue date ※ 28 August 2021
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THPAB209	Tracking Complex Re-Circulating Machines with PLACET2	wakefield, radiation, electron, synchrotron	4197
	R.A.J. Costa, A. Latina CERN, Geneva, Switzerland
	We present the latest version of the multi-particle tracking package PLACET2. This software was designed to track multiple electron bunches through re-circulating machines with complex topologies, such as the recombination complex of the Compact Linear Collider (CLIC), energy-recovery linacs such as the Large Hadron-Electron Collider (LHeC), racetracks and others. This update also expands the capabilities of PLACET2 to track heavier particles such as muons. In addition to simulation, PLACET2 was also developed to allow beamline optimization scans, evaluating beam properties and tuning the beamline parameters at runtime either standalone or accessing the optimization tools present in the Octave and Python packages, with which it interfaces. This paper presents and benchmarks PLACET2’s latest features, such as coherent and incoherent synchrotron radiation, long and short wakefields and power extraction.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB209
About •	paper received ※ 18 May 2021 paper accepted ※ 13 July 2021 issue date ※ 27 August 2021
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THPAB300	Structure Design and Motion Analysis of 6-DOF Sample Positioning Platform	controls, radiation, GUI, synchrotron	4387
	G.Y. Wang, J.X. Chen, L. Liu, R.H. Liu, C.J. Ning, A.X. Wang, J.B. Yu, Y.J. Yu, J.S. Zhang IHEP CSNS, Guangdong Province, People’s Republic of China L. Kang IHEP, Beijing, People’s Republic of China
	with the development of synchrotron radiation (SR) light source technology, in order to meet the requirements of sample positioning platform of some beamline stations, such as adjusting resolution at the nanometer level and having larger sample scanning distance, a six degree of freedom positioning platform based on spacefab structure was developed. The key technologies such as coordinate parameter transformation, kinematics analysis, and adjustment decoupling algorithm of 6-DOF pose adjustment system of SpaceFAB positioning platform are mainly studied. A 6-DOF platform driven by a stepping motor is designed and manufactured. The control system of the 6-DOF Platform Based on bus control is developed, and the adjustment accuracy is tested. The repeated positioning accuracy of the platform in three directions is 0.019 mm, and that of rotation is 0.011 ° in three directions. The test results verify the correctness of the theoretical analysis of SpaceFAB structure and the rationality of mechanism design. The research on the platform motion algorithm and control system has important reference value for the follow-up research of large stroke nano-6-dof positioning platform.
	Poster THPAB300 [1.517 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB300
About •	paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 02 September 2021
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Paper

Title

Other Keywords

Page

MOPAB245

Theoretical Analysis of the Conditions for an Isochronous and CSR-Immune Triple-Bend Achromat with Stable Optics

emittance, dipole, optics, radiation

786

C. Zhang, Y. Jiao
IHEP, Beijing, People’s Republic of China
C.-Y. Tsai
HUST, Wuhan, People’s Republic of China

Funding: National Natural Science Foundation of China (No. 11922512), Youth Innovation Promotion Association of Chinese Academy of Sciences (No. Y201904), National Key R&D Program of China (No. 2016YFA0401900)
Transport of high-brightness beams with minimum degradation of the phase space quality is pursued in modern accelerators. For the beam transfer line which commonly consists of bending magnets, it would be desirable if the transfer line can be isochronous and coherent synchrotron radiation (CSR)-immune. For multi-pass transfer line, the achromatic cell designs with stable optics would bring great convenience. In this paper, based on the transfer matrix formalism and the CSR point-kick model, we report the detailed theoretical analysis and derive the condition for a triple-bend achromat with stable optics in which the first-order longitudinal dispersion (i.e., R56) and the CSR-induced emittance growth can be eliminated. The derived condition suggests a new way of designing the bending magnet beamline that can be applied to the free-electron laser (FEL) spreader and energy recovery linac (ERL) recirculation loop.

Poster MOPAB245 [0.530 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB245

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paper received ※ 12 May 2021 paper accepted ※ 08 June 2021 issue date ※ 27 August 2021

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TUPAB255

Longitudinal Beam Dynamics and Coherent Synchrotron Radiation at cSTART

synchrotron, radiation, electron, storage-ring

2050

M. Schwarz, E. Bründermann, D. El Khechen, B. Härer, A. Malygin, A.-S. Müller, M.J. Nasse, A.I. Papash, R. Ruprecht, J. Schäfer, M. Schuh, P. Wesolowski
KIT, Karlsruhe, Germany

The compact STorage ring for Accelerator Research and Technology (cSTART) project aims to store electron bunches of LWFA-like beams in a very large momentum acceptance storage ring. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for cSTART to benchmark and emulate laser-wakefield accelerator-like beams. In a second stage a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and Helmholtz Institute Jena (HIJ). With an energy of 50 MeV and damping times of several seconds, the electron beam does not reach equilibrium emittance. Furthermore, the critical frequency of synchrotron radiation is 53 THz and in the same order as the bunch spectrum, which implies that the entire bunch radiates coherently. We perform longitudinal particle tracking simulations to investigate the evolution of the bunch length and spectrum as well as the emitted coherent synchrotron radiation. Finally, different options for the RF system are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB255

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paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 29 August 2021

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TUPAB264

Shielding of CSR Wake in a Drift

impedance, shielding, radiation, wakefield

2079

G. Stupakov
SLAC, Menlo Park, California, USA

Funding: Work supported by the Department of Energy, contract DE-AC03-76SF00515.
A one-dimensional model of coherent synchrotron radiation (CSR) wakefield developed in Refs. [*,**] is used in computer codes for the simulation of relativistic electron beams. It includes transient effects at the entrance and exit from a bending magnet of finite length. In the ultra-relativistic limit, v=c, the exit CSR wake decays inversely proportional to the distance from the magnet end. To calculate the total energy loss of the beam one needs to integrate this wake to infinity, but the integral diverges. This means that one has to either drop the assumption of the infinite value of the Lorentz factor or take into account the shielding effect of the metal walls in the vacuum chamber. In practice, the latter effect is often dominant. In this work, we derive formulas for the CSR wake in the drift after an exit from the magnet that incorporates the shielding by two parallel metal plates. They allow computing the energy loss of different particles in the beam.
* E. L. Saldin, E. A. Schneidmiller, and M. V. Yurkov. NIMA v. 398, p. 373 (1997).
** G. Stupakov and P. Emma. In: Proceedings of 8th EPAC. Paris, France, 2002, p. 1479.

Poster TUPAB264 [0.661 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB264

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paper received ※ 10 May 2021 paper accepted ※ 25 June 2021 issue date ※ 22 August 2021

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TUPAB318

The Beamline Safety Interlock System of Taiwan Photon Source

radiation, vacuum, photon, controls

2239

C.F. Chang, C.Y. Chang, C.Y. Liu, H.Y. Yan
NSRRC, Hsinchu, Taiwan

The energy of synchrotron radiation generated by bremsstrahlung radiation and magnet is rather high, which may cause serious radiation damage to human body or even imperil people’s life. The beamline therefore must be equipped with radiation-protection system; in addition, the overheat of optical components exposed to synchrotron radiation will lead to the damage of optical components and devices. In consequence, the beamline should be furnished with the cooling-protection system to cool down optical components and devices. The Beamline Safety Interlock System targets at protecting the personnel and the safety of devices, limiting the radiation dose to a security value for experimental personnel or staffs exposing to radiation on the site as well as preventing beamline components from being exposed to overheat or vacuum damages to improve the effectiveness of beamline.

Poster TUPAB318 [3.440 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB318

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paper received ※ 09 May 2021 paper accepted ※ 10 June 2021 issue date ※ 31 August 2021

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WEPAB002

The Interaction Region of the Electron-Ion Collider EIC

electron, radiation, synchrotron, detector

2574

H. Witte, J. Adam, M. Anerella, E.C. Aschenauer, J.S. Berg, M. Blaskiewicz, A. Blednykh, W. Christie, J.P. Cozzolino, K.A. Drees, D.M. Gassner, K. Hamdi, C. Hetzel, H.M. Hocker, D. Holmes, A. Jentsch, A. Kiselev, P. Kovach, H. Lovelace III, Y. Luo, G.J. Mahler, A. Marone, G.T. McIntyre, C. Montag, R.B. Palmer, B. Parker, S. Peggs, S.R. Plate, V. Ptitsyn, G. Robert-Demolaize, C.E. Runyan, J. Schmalzle, K.S. Smith, S. Tepikian, P. Thieberger, J.E. Tuozzolo, F.J. Willeke, Q. Wu, Z. Zhang
BNL, Upton, New York, USA
B.R. Gamage, T.J. Michalski, V.S. Morozov, M.L. Stutzman, W. Wittmer
JLab, Newport News, Virginia, USA
M.K. Sullivan
SLAC, Menlo Park, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
This paper presents an overview of the Interaction Region (IR) design for the planned Electron-Ion Collider (EIC) at Brookhaven National Laboratory. The IR is designed to meet the requirements of the nuclear physics community *. The IR design features a ±4.5 m free space for the detector; a forward spectrometer magnet is used for the detection of hadrons scattered under small angles. The hadrons are separated from the neutrons allowing detection of neutrons up to ±4 mrad. On the rear side, the electrons are separated from photons using a weak dipole magnet for the luminosity monitor and to detect scattered electrons (e-tagger). To avoid synchrotron radiation backgrounds in the detector no strong electron bending magnet is placed within 40 m upstream of the IP. The magnet apertures on the rear side are large enough to allow synchrotron radiation to pass through the magnets. The beam pipe has been optimized to reduce the impedance; the total power loss in the central vacuum chamber is expected to be less than 90 W. To reduce risk and cost the IR is designed to employ standard NbTi superconducting magnets, which are described in a separate paper.
* An Assessment of U.S.-Based Electron-Ion Collider Science. (2018). Washington, D.C.: National Academies Press. https://doi.org/10.17226/25171

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB002

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paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 31 August 2021

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WEPAB234

Simulating Two Dimensional Coherent Synchrotron Radiation in Python

emittance, simulation, radiation, electron

3177

W. Lou, Y. Cai, C.E. Mayes, G.R. White
SLAC, Menlo Park, California, USA

Coherent Synchrotron Radiation (CSR) in bending magnets poses an important limit for electron beams to reach high brightness in novel accelerators. While the longitudinal wakefield has been well studied in one-dimensional CSR theory and implemented in various simulation codes, transverse wakefields have received less attention. Following the recently developed two-dimensional CSR theory, we developed a Python code simulating the steady-state two-dimensional CSR effects. The computed CSR wakes have been benchmarked with theory and other simulation codes. To speed up computation speed, the code applies vectorization, parallel processing, and Numba in Python.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB234

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paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 20 August 2021

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WEPAB240

Increasing the Single-Bunch Instability Threshold by Bunch Splitting Due to RF Phase Modulation

synchrotron, radiation, detector, electron

3193

J.L. Steinmann, E. Blomley, M. Brosi, E. Bründermann, A. Mochihashi, A.-S. Müller, M. Schuh, P. Schönfeldt
KIT, Karlsruhe, Germany

Funding: This work is funded by the BMBF contract number: 05K16VKA.
RF phase modulation at twice the synchrotron frequency can be used to split a stored electron bunch into two or more bunchlets orbiting each other. We report on time-resolved measurements at the Karlsruhe Research Accelerator (KARA), where this bunch splitting was used to increase the threshold current of the microbunching instability, happening in the short-bunch operation mode. Turning the modulation on and off reproducibly affects the sawtooth behavior of the emitted coherent synchrotron radiation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB240

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paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 18 August 2021

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THXA05

A Fast Method of 2D Calculation of Coherent Synchrotron Radiation Wakefield in Relativistic Beams

radiation, electron, dipole, synchrotron

3696

J. Tang, Z. Huang, G. Stupakov
SLAC, Menlo Park, California, USA

Coherent Synchrotron Radiation (CSR) is regarded as one of the most important reasons that limit beam brightness in modern accelerators. CSR wakefield is often computed in a 1D assuming a line charge, which can become invalid when the beam has a large transverse extension and small bunch length. On the other hand, the existing 2D or 3D codes are often computationally inefficient or incomplete. In our previous work * we developed a new model for fast computation of 2D CSR wakefield in relativistic beams with Gaussian distribution. Here we further generalize this model to achieve self-consistent computation compatible with arbitrary beam distribution and nonlinear magnetic lattice with particle tracking. These new features can enable us to perform realistic simulations and study the physics of CSR beyond 1D in electron beams with extreme short bunch length and high peak current.
* J. Tang and G. Stupakov. NAPAC2019, paper WEPLS09 (2019).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA05

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paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 21 August 2021

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THPAB065

Experimental Verification of the Source of Excessive Helical SCU Heat Load at APS

vacuum, radiation, photon, synchrotron

3904

V. Sajaev, J.C. Dooling, K.C. Harkay
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Immediately after the installation of the Helical superconducting undulator (HSCU) in the APS storage ring, higher than expected heating was observed in the cryogenic cooling system. Steering the electron beam orbit in the upstream dipole reduced the amount of synchrotron radiation reaching into the HSCU and allowed the device to properly cool and operate. The simplest explanation of the excessive heat load was higher than expected heat transfer from the vacuum chamber to the magnet coils. However, modeling of the synchrotron radiation interaction with the HSCU vacuum chamber showed that Compton scattering could also result in synchrotron radiation penetrating the vacuum chamber and depositing energy directly into the HSCU coils**. In this paper, we present experimental evidence that the excessive heat load of the HSCU coils is not caused by the heat transfer from the vacuum chamber but resulted from the synchrotron radiation penetrating the vacuum chamber.
* M. Kasa et. al., Phys. Rev. AB, v. 23 050701 (2020)
** J. Dooling et. al., IPAC 2019 Proc., THPTS093 (2019)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB065

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paper received ※ 12 May 2021 paper accepted ※ 02 September 2021 issue date ※ 16 August 2021

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THPAB079

Design Study on Beam Size Measurement System Using SR Interferometry for Low Beam Current

electron, synchrotron, radiation, storage-ring

3949

W. Li, P. Liu, Y.K. Wu, J. Yan
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
To enable reliable measurements of the small vertical size of the electron beam in the Duke storage ring, a measurement system is being developed using synchrotron radiation interferometry (SRI). By relating the transverse beam size to the transverse spatial coherence of synchrotron radiation from a dipole magnet according to the Van Cittert-Zernike theorem, the transverse beam size can be inferred by recording and fitting the interference fringe as a function of the characteristic features of the interference filter used. In this paper, we describe the preliminary design of such a measurement system and present design considerations to make it possible to measure the electron beam vertical size for a wide range of electron beam energies and currents. Especially this system will be optimized to measure the electron beam size for low current operation down to 50 to 100~μA. This beam size measurement system will be used as an important beam diagnostic for the intrabeam scattering research at the Duke storage ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB079

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paper received ※ 27 May 2021 paper accepted ※ 12 July 2021 issue date ※ 28 August 2021

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THPAB209

Tracking Complex Re-Circulating Machines with PLACET2

wakefield, radiation, electron, synchrotron

4197

R.A.J. Costa, A. Latina
CERN, Geneva, Switzerland

We present the latest version of the multi-particle tracking package PLACET2. This software was designed to track multiple electron bunches through re-circulating machines with complex topologies, such as the recombination complex of the Compact Linear Collider (CLIC), energy-recovery linacs such as the Large Hadron-Electron Collider (LHeC), racetracks and others. This update also expands the capabilities of PLACET2 to track heavier particles such as muons. In addition to simulation, PLACET2 was also developed to allow beamline optimization scans, evaluating beam properties and tuning the beamline parameters at runtime either standalone or accessing the optimization tools present in the Octave and Python packages, with which it interfaces. This paper presents and benchmarks PLACET2’s latest features, such as coherent and incoherent synchrotron radiation, long and short wakefields and power extraction.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB209

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paper received ※ 18 May 2021 paper accepted ※ 13 July 2021 issue date ※ 27 August 2021

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THPAB300

Structure Design and Motion Analysis of 6-DOF Sample Positioning Platform

controls, radiation, GUI, synchrotron

4387

G.Y. Wang, J.X. Chen, L. Liu, R.H. Liu, C.J. Ning, A.X. Wang, J.B. Yu, Y.J. Yu, J.S. Zhang
IHEP CSNS, Guangdong Province, People’s Republic of China
L. Kang
IHEP, Beijing, People’s Republic of China

with the development of synchrotron radiation (SR) light source technology, in order to meet the requirements of sample positioning platform of some beamline stations, such as adjusting resolution at the nanometer level and having larger sample scanning distance, a six degree of freedom positioning platform based on spacefab structure was developed. The key technologies such as coordinate parameter transformation, kinematics analysis, and adjustment decoupling algorithm of 6-DOF pose adjustment system of SpaceFAB positioning platform are mainly studied. A 6-DOF platform driven by a stepping motor is designed and manufactured. The control system of the 6-DOF Platform Based on bus control is developed, and the adjustment accuracy is tested. The repeated positioning accuracy of the platform in three directions is 0.019 mm, and that of rotation is 0.011 ° in three directions. The test results verify the correctness of the theoretical analysis of SpaceFAB structure and the rationality of mechanism design. The research on the platform motion algorithm and control system has important reference value for the follow-up research of large stroke nano-6-dof positioning platform.

Poster THPAB300 [1.517 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB300

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paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 02 September 2021

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