SRF2023 - List of Authors (Posen, S.)

Paper	Title	Page
SATUT03	Application
	S. Posen Fermilab, Batavia, Illinois, USA
	Nb₃Sn cavities and other applications for small accelerators, such as for medical application, with a Cryocooler may be one of the major potential applications of SRF in coming years. Axion and dark matter will be another potential use of SRF cavities for fundamental physics. FNAL is also developing small SRF cavities coupled to quantum computer. This lecture will provide some overview of applications SRF¿based.
	Slides SATUT03 [21.485 MB]
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MOPMB014	NbTi Thin Film SRF Cavities for Dark Matter Search	96
SUSPB008	use link to see paper's listing under its alternate paper code
	G. Marconato Università degli Studi di Padova, Padova, Italy D. Alesini, A. D’Elia, D. Di Gioacchino, C. Gatti, C. Ligi, G. Maccarrone, A. Rettaroli, S. Tocci LNF-INFN, Frascati, Italy O. Azzolini, R. Caforio, E. Chyhyrynets, D. Fonnesu, D. Ford, V.A. Garcia, G. Keppel, C. Pira, A. Salmaso, F. Stivanello INFN/LNL, Legnaro (PD), Italy C. Braggio Univ. degli Studi di Padova, Padova, Italy D. D’Agostino, U. Gambardella INFN-Salerno, Baronissi, Salerno, Italy S. Posen Fermilab, Batavia, Illinois, USA
	Funding: Resources from U.S. DOE, Ofce of Science, NQISRC, SQMS contract No DE-AC02-07CH11359. Also from EU’s Horizon 2020 Research and Innovation programme, Grant Agreement No 101004730; INFN CSNV exp. SAMARA The search for dark matter is now looking at ALPs (axion-like particles) as a very promising candidate to understand our universe. Within this framework, we explore the possibility to use NbTi thin film coatings on Cu resonating cavities to investigate the presence of axions in the range of 35-45 µeV mass by coupling the axion to a very strong magnetic field inside the cavity, causing its conversion to a photon which is subsequently detected. In this work the chemical treatments and DC magnetron sputtering details of the preparation of 9 GHz, 7 GHz, and 3.9 GHz resonant cavities and their quality factor measurements at different applied magnetic fields are presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB014
About •	Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 26 July 2023
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MOPMB030	Medium Temperature Furnace Baking of Low-beta 650 MHz Five-cell Cavities	158
	G. Wu, S.K. Chandrasekaran, V. Chouhan, G.V. Eremeev, F. Furuta, K.E. McGee, A.A. Murthy, A.V. Netepenko, J.P. Ozelis, H. Park, S. Posen Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Medium Temperature baking of low beta 650 MHz cavities was conducted in a UHV furnace. A systematic study of cavity surface resistance components, residual and BCS, was conducted, including analyzing surface resistance due to trapped magnetic flux. Cavities showed an average 4.5 nano-ohm surface resistance at 17 MV/m under 2 K, which meets PIP-II specifications with a 40% margin. The results provided helpful information for the PIP-II project to optimize the cavity processing recipe for cryomodule application. The results were compared to the 1.3 GHz cavity that received a similar furnace baking.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB030
About •	Received ※ 19 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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MOPMB047	Commissioning of Dedicated Furnace for Nb₃Sn Coatings of 2.6 GHz Single Cell Cavities	216
SUSPB018	use link to see paper's listing under its alternate paper code
	P.A. Kulyavtsev, G.V. Eremeev, S. Posen, B. Tennis Fermilab, Batavia, Illinois, USA J. Zasadzinski IIT, Chicago, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. We present the results of commissioning a dedicated furnace for Nb₃Sn coatings of 2.6GHz single cell cavities. Nb₃Sn is a desired coating due to its high critical temperature and smaller surface resistance compared to bulk Nb. Usage of Nb₃Sn coated cavities will greatly reduce operating costs due to its higher operating temperature providing decreased cooling costs. Tin is deposited in the bulk Nb cavity by use of a tin chloride nucleation agent and tin vapor diffusion. Analysis of the resultant coating was performed using SEM/EDS to verify successful formation of desired Nb:Sn phase. Witness samples located in line of sight of the source were analyzed in order to understand the coating efficacy. The cavity’s performance was assessed in the Vertical Test Stand (VTS) at Fermilab.
	Poster MOPMB047 [4.858 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB047
About •	Received ※ 26 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 08 July 2023
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MOPMB063	Multipacting Processing in Cryomodules for LCLS-II and LCLS-II-HE	259
	A.T. Cravatta, T.T. Arkan, D. Bafia, J.A. Kaluzny, S. Posen Fermilab, Batavia, Illinois, USA S. Aderhold, M. Checchin, D. Gonnella, J. Hogan, J.T. Maniscalco, J. Nelson, R.D. Porter, L.M. Zacarias SLAC, Menlo Park, California, USA M.A. Drury, H. Vennekate JLab, Newport News, VA, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Multipacting (MP) is a phenomenon which can affect stability in particle accelerators and limit performance in superconducting radio frequency cavities. In the TESLA shaped, 1.3 GHz, 9-cell cavities used in the LCLS-II (L2) and LCLS-II-HE (HE) projects, the MP-band (~17-24 MV/m) lies within the required accelerating gradients. For HE, the operating gradient of 20.8 MV/m lies well within the MP-band and cryomodule testing has confirmed that this is an issue. As such, MP processing for the HE cryomodule test program will be discussed. Early results on MP processing in cryomodules installed in the L2 linac will also be presented, demonstrating that the methods used in cryomodule acceptance testing are also successful at conditioning MP in the accelerator and that this processing is preserved in the mid-term.
	Poster MOPMB063 [1.066 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB063
About •	Received ※ 25 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 30 June 2023
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MOPMB072	LCLS-II-HE Cavity Qualification Testing	279
	J.T. Maniscalco, S. Aderhold, M. Checchin, D. Gonnella, J. Hogan, R.D. Porter SLAC, Menlo Park, California, USA T.T. Arkan, D. Bafia, A.T. Cravatta, J.A. Kaluzny, S. Posen Fermilab, Batavia, Illinois, USA M.E. Bevins, A.J. Grabowski, C.E. Reece, H. Vennekate JLab, Newport News, VA, USA
	Acceptance testing of the LCLS-II-HE production cavities is approximately 65% complete. In this report, we present details of the test results, including summaries of the quench fields, intrinsic quality factors, and experience with field emission. We also offer an outlook on the remaining tests to be performed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB072
About •	Received ※ 20 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 07 July 2023
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MOPMB081	Microphonics in the LCLS-II Superconducting Linac	302
	R.D. Porter, S. Aderhold, L.E. Alsberg, D. Gonnella, J. Nelson, N.R. Neveu, L.M. Zacarias SLAC, Menlo Park, California, USA A.T. Cravatta, J.P. Holzbauer, S. Posen Fermilab, Batavia, Illinois, USA M.A. Drury, M.D. McCaughan, C.M. Wilson JLab, Newport News, Virginia, USA G. Gaitan, N.A. Stilin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by the LCLS-II project The LCLS-II project has installed a new superconducting linac at SLAC that consists of 35 1.3 GHz cryomodules and 2 3.9 GHz cryomodules. The linac will provide a 4 GeV electron beam for generating soft and hard X-ray pulses. Cavity detuning induced by microphonics was a significant design challenge for the LCLS-II cryomodules. Cryomodules were produced that were within the detuning specification (10 Hz for 1.3 GHz cryomodules) on test stands. Here we present first measurements of the microphonics in the installed LCLS-II superconducting linac. Overall, the microphonics in the linac are manageable with 94% of cavities coming within the detune specification. Only two cavities are gradient limited due to microphonics. We identify a leaking cool down valve as the source of microphonics limiting those two cavities.
	Poster MOPMB081 [1.284 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB081
About •	Received ※ 18 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 01 July 2023
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MOPMB090	Measuring Q₀ in LCLS-II Cryomodules Using Helium Liquid Level	327
	L.M. Zacarias, S. Aderhold, D. Gonnella, J.T. Maniscalco, J. Nelson, R.D. Porter SLAC, Menlo Park, California, USA A.T. Cravatta, J.P. Holzbauer, S. Posen Fermilab, Batavia, Illinois, USA M.A. Drury, M.D. McCaughan, C.M. Wilson JLab, Newport News, Virginia, USA
	The nitrogen-doped cavities used in the Linac Coherent Light Source II (LCLS-II) cryomodules have shown an unprecedented high Q₀ in vertical and cryomodule testing compared with cavities prepared with standard methods. While demonstration of high Q₀ in the test stand has been achieved, maintaining that performance in the linac is critical to the success of LCLS-II and future accelerator projects. The LCLS-II cryomodules required a novel method of measuring Q₀, due to hardware incompatibilities with existing procedures. Initially developed at Jefferson Lab during cryomodule acceptance testing before being used in the tunnel at SLAC, we use helium liquid level data to estimate the heat generated by cavities. We first establish the relationship between the rate of helium evaporation from known heat loads using electric heaters, and then use that relationship to determine heat from an RF load. Here we present the full procedure along with the development process, lessons learned, and reproducibility while demonstrating for the first time that world record Q₀ can be maintained within the real accelerator environment.
	Poster MOPMB090 [1.867 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB090
About •	Received ※ 20 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 13 July 2023
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TUPTB001	Demonstration of Niobium Tin in 218 MHz Low-Beta Quarter Wave Accelerator Cavity	388
	T.B. Petersen, G. Chen, B.M. Guilfoyle, M. Kedzie, M.P. Kelly, T. Reid ANL, Lemont, Illinois, USA G.V. Eremeev, S. Posen, B. Tennis Fermilab, Batavia, Illinois, USA
	A 218 MHz quarter wave niobium cavity has been fabricated for the purpose of demonstrating Nb₃Sn technology on a low-beta accelerator cavity. Niobium-tin has been established as a promising next generation SRF material, but development has focused primarily in high-beta elliptical cell cavities. This material has a significantly higher TC than niobium, allowing for design of higher frequency quarter wave cavities (that are subsequently smaller) as well as for significantly lowered cooling requirements (possibly leading to cryocooler based de-signs). The fabrication, initial cold testing, and Nb₃Sn coating are discussed as well as test plans and details of future applications.
	Poster TUPTB001 [0.653 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB001
About •	Received ※ 16 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 08 July 2023
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TUPTB010	Preservation of the High Quality Factor and Accelerating Gradient of Nb₃Sn-Coated Cavity During Pair Assembly	405
	G.V. Eremeev, S. Cheban, S. Posen, B. Tennis Fermilab, Batavia, Illinois, USA J.F. Fischer, D. Forehand, U. Pudasaini, A.V. Reilly, R.A. Rimmer JLab, Newport News, Virginia, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Two CEBAF 5-cell accelerator cavities have been coated with Nb₃Sn film using the vapor diffusion technique. One cavity was coated in the Jefferson Lab Nb₃Sn cavity coating system, and the other in the Fermilab Nb₃Sn coating system. Both cavities were measured at 4 K and 2 K in the vertical dewar test in each lab and then assembled into a cavity pair at Jefferson Lab. Previous attempts to assemble Nb₃Sn cavities into a cavity pair degraded the superconducting properties of Nb₃Sn-coated cavities. This contribution discusses the efforts to identify and mitigate the pair assembly challenges and will present the results of the vertical tests before and after pair assembly. Notably, one of the cavities reached the highest gradient above 80 mT in the vertical test after the pair assembly.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB010
About •	Received ※ 23 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 02 July 2023 — Issue date ※ 09 July 2023
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WEIXA07	Review of Thermal Treatments: Effects, Reliability, and Open Questions
	S. Posen Fermilab, Batavia, Illinois, USA
	Over years of research and development, a variety of thermal treatments have been developed for bulk niobium cavities, providing different high performance capabilities for SRF resonators depending on the application. Key considerations include maximum field, quality factor at a desired field, sensitivity to trapped flux, and reproducibility of performance. In this talk, we overview the last decade of development of heat treatments, as well as what is reliability achieved at different laboratories, and open questions.
	Slides WEIXA07 [6.423 MB]
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WEPWB109	PI Loop Resonance Control for the Dark Photon Experiment at 2 K using a 2.6 GHz SRF cavity	847
	C. Contreras-Martinez, B. Giaccone, O.S. Melnychuk, A.V. Netepenko, Y.M. Pischalnikov, S. Posen, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Two 2.6 GHz cavities are being used for dark photon search at VTS in FNAL. During testing at 2 K the cavities experience frequency detuning caused by microphonics and slow frequency drifts. The experiment requires that the two cavities have the same frequency within 5 Hz. These two cavities are equipped with frequency tuners consisting of three piezo actuators. The piezo actuators are used for fine-fast frequency tuning. A PI loop utilizing the piezos was used to maintain both cavities at the same frequency, and the results are presented.
	Poster WEPWB109 [1.151 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB109
About •	Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 18 July 2023
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WEPWB120	Flux Expulsion Testing for LCLS-II-HE Cavity Production	876
	J.T. Maniscalco, S. Aderhold, M. Checchin, D. Gonnella, R.D. Porter SLAC, Menlo Park, California, USA T.T. Arkan, D. Bafia, J.A. Kaluzny, S. Posen Fermilab, Batavia, Illinois, USA M.E. Bevins, A.J. Grabowski, J. Hogan, C.E. Reece, D. Savransky, H. Vennekate JLab, Newport News, VA, USA
	Nitrogen-doped niobium SRF cavities are sensitive to trapped magnetic flux, which decreases the cavity intrinsic Q₀. Prior experimental results have shown that heat treatments to 900°C and higher can result in stronger flux expulsion during cooldown; the precise temperature required tends to vary by vendor lot/ingot of the niobium material used in the cavity cells. For LCLS-II-HE, to ensure sufficient flux expulsion in all cavities, we built and tested single-cell cavities to determine this required temperature for each vendor lot of niobium material to be used in cavity cells. In this report, we present the results of the single-cell flux expulsion testing and the Q₀ of the nine-cell cavities built using the characterized vendor lots. We discuss mixing material from different vendor lots, examine the lessons learned, and finally present an outlook on possible refinements to the single-cell technique.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB120
About •	Received ※ 15 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 13 July 2023
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WEPWB133	Testing of the 2.6 GHz SRF Cavity Tuner for the Dark Photon Experiment at 2 K	907
	C. Contreras-Martinez, B. Giaccone, I.V. Gonin, T.N. Khabiboulline, O.S. Melnychuk, Y.M. Pischalnikov, S. Posen, O.V. Pronitchev, J.C. Yun Fermilab, Batavia, Illinois, USA
	At FNAL two 2.6 GHz SRF cavities are being used to search for dark photons, the experiment can be conducted at 2 K or in a dilution refrigerator. Precise frequency tuning is required for these two cavities so they can be matched in frequency. A cooling capacity constraint on the dilution refrigerator only allows piezo actuators to be part of the design of the 2.6 GHz cavity tuner. The tuner is equipped with three encapsulated piezo that deliver the long- and short-range frequency tuning. Modifications were implemented on the first tuner design due to the low forces on the piezos due to the cavity. Three brass rods with Belleville washers were added to the design to increase the overall force on the piezos. The results at 2 K of testing this tuner with and without the modification will be presented.
	Poster WEPWB133 [0.829 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB133
About •	Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 July 2023
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THIXA06	Dark Matter and Gravitational Waves Experiments with SRF Cavities
	B. Giaccone, A. Grassellino, S. Posen, A.S. Romanenko Fermilab, Batavia, Illinois, USA
	Funding: This material is based upon work supported by the U.S. DOE, SC, National QIS Research Centers, Superconducting Quantum Materials and Systems Center (SQMS) under contract n. DE-AC02-07CH11359 Recent efforts have shown that the SRF technology developed for accelerators can be successfully applied to new applications, including quantum computing, dark matter searches and beyond the standard model physics. The ultra-high quality factor of SRF cavities can allow to achieve unprecedented sensitivity in fields outside of the usual accelerator applications, for examples in dark photon and axion searches (both as dark matter candidates and lab-produced particles). Applications of SRF cavities for gravitational waves searches are also being investigated. The SQMS Physics and Sensing thrust is leveraging SRF cavities and QIS to search for new particles and BSM physics. This talk will highlight experiments where SRF cavities have already set experimental bounds on new physics.
	Slides THIXA06 [5.984 MB]
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Paper

Title

Page

SATUT03

Application

S. Posen
Fermilab, Batavia, Illinois, USA

Nb₃Sn cavities and other applications for small accelerators, such as for medical application, with a Cryocooler may be one of the major potential applications of SRF in coming years. Axion and dark matter will be another potential use of SRF cavities for fundamental physics. FNAL is also developing small SRF cavities coupled to quantum computer. This lecture will provide some overview of applications SRF¿based.

Slides SATUT03 [21.485 MB]

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MOPMB014

NbTi Thin Film SRF Cavities for Dark Matter Search

96

SUSPB008

use link to see paper's listing under its alternate paper code

G. Marconato
Università degli Studi di Padova, Padova, Italy
D. Alesini, A. D’Elia, D. Di Gioacchino, C. Gatti, C. Ligi, G. Maccarrone, A. Rettaroli, S. Tocci
LNF-INFN, Frascati, Italy
O. Azzolini, R. Caforio, E. Chyhyrynets, D. Fonnesu, D. Ford, V.A. Garcia, G. Keppel, C. Pira, A. Salmaso, F. Stivanello
INFN/LNL, Legnaro (PD), Italy
C. Braggio
Univ. degli Studi di Padova, Padova, Italy
D. D’Agostino, U. Gambardella
INFN-Salerno, Baronissi, Salerno, Italy
S. Posen
Fermilab, Batavia, Illinois, USA

Funding: Resources from U.S. DOE, Ofce of Science, NQISRC, SQMS contract No DE-AC02-07CH11359. Also from EU’s Horizon 2020 Research and Innovation programme, Grant Agreement No 101004730; INFN CSNV exp. SAMARA
The search for dark matter is now looking at ALPs (axion-like particles) as a very promising candidate to understand our universe. Within this framework, we explore the possibility to use NbTi thin film coatings on Cu resonating cavities to investigate the presence of axions in the range of 35-45 µeV mass by coupling the axion to a very strong magnetic field inside the cavity, causing its conversion to a photon which is subsequently detected. In this work the chemical treatments and DC magnetron sputtering details of the preparation of 9 GHz, 7 GHz, and 3.9 GHz resonant cavities and their quality factor measurements at different applied magnetic fields are presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB014

About •

Received ※ 18 June 2023 — Revised ※ 22 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 26 July 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB030

Medium Temperature Furnace Baking of Low-beta 650 MHz Five-cell Cavities

158

G. Wu, S.K. Chandrasekaran, V. Chouhan, G.V. Eremeev, F. Furuta, K.E. McGee, A.A. Murthy, A.V. Netepenko, J.P. Ozelis, H. Park, S. Posen
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Medium Temperature baking of low beta 650 MHz cavities was conducted in a UHV furnace. A systematic study of cavity surface resistance components, residual and BCS, was conducted, including analyzing surface resistance due to trapped magnetic flux. Cavities showed an average 4.5 nano-ohm surface resistance at 17 MV/m under 2 K, which meets PIP-II specifications with a 40% margin. The results provided helpful information for the PIP-II project to optimize the cavity processing recipe for cryomodule application. The results were compared to the 1.3 GHz cavity that received a similar furnace baking.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB030

About •

Received ※ 19 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023

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MOPMB047

Commissioning of Dedicated Furnace for Nb₃Sn Coatings of 2.6 GHz Single Cell Cavities

216

SUSPB018

use link to see paper's listing under its alternate paper code

P.A. Kulyavtsev, G.V. Eremeev, S. Posen, B. Tennis
Fermilab, Batavia, Illinois, USA
J. Zasadzinski
IIT, Chicago, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
We present the results of commissioning a dedicated furnace for Nb₃Sn coatings of 2.6GHz single cell cavities. Nb₃Sn is a desired coating due to its high critical temperature and smaller surface resistance compared to bulk Nb. Usage of Nb₃Sn coated cavities will greatly reduce operating costs due to its higher operating temperature providing decreased cooling costs. Tin is deposited in the bulk Nb cavity by use of a tin chloride nucleation agent and tin vapor diffusion. Analysis of the resultant coating was performed using SEM/EDS to verify successful formation of desired Nb:Sn phase. Witness samples located in line of sight of the source were analyzed in order to understand the coating efficacy. The cavity’s performance was assessed in the Vertical Test Stand (VTS) at Fermilab.

Poster MOPMB047 [4.858 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB047

About •

Received ※ 26 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 08 July 2023

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMB063

Multipacting Processing in Cryomodules for LCLS-II and LCLS-II-HE

259

A.T. Cravatta, T.T. Arkan, D. Bafia, J.A. Kaluzny, S. Posen
Fermilab, Batavia, Illinois, USA
S. Aderhold, M. Checchin, D. Gonnella, J. Hogan, J.T. Maniscalco, J. Nelson, R.D. Porter, L.M. Zacarias
SLAC, Menlo Park, California, USA
M.A. Drury, H. Vennekate
JLab, Newport News, VA, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Multipacting (MP) is a phenomenon which can affect stability in particle accelerators and limit performance in superconducting radio frequency cavities. In the TESLA shaped, 1.3 GHz, 9-cell cavities used in the LCLS-II (L2) and LCLS-II-HE (HE) projects, the MP-band (~17-24 MV/m) lies within the required accelerating gradients. For HE, the operating gradient of 20.8 MV/m lies well within the MP-band and cryomodule testing has confirmed that this is an issue. As such, MP processing for the HE cryomodule test program will be discussed. Early results on MP processing in cryomodules installed in the L2 linac will also be presented, demonstrating that the methods used in cryomodule acceptance testing are also successful at conditioning MP in the accelerator and that this processing is preserved in the mid-term.

Poster MOPMB063 [1.066 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB063

About •

Received ※ 25 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 30 June 2023

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MOPMB072

LCLS-II-HE Cavity Qualification Testing

279

J.T. Maniscalco, S. Aderhold, M. Checchin, D. Gonnella, J. Hogan, R.D. Porter
SLAC, Menlo Park, California, USA
T.T. Arkan, D. Bafia, A.T. Cravatta, J.A. Kaluzny, S. Posen
Fermilab, Batavia, Illinois, USA
M.E. Bevins, A.J. Grabowski, C.E. Reece, H. Vennekate
JLab, Newport News, VA, USA

Acceptance testing of the LCLS-II-HE production cavities is approximately 65% complete. In this report, we present details of the test results, including summaries of the quench fields, intrinsic quality factors, and experience with field emission. We also offer an outlook on the remaining tests to be performed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB072

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Received ※ 20 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 07 July 2023

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MOPMB081

Microphonics in the LCLS-II Superconducting Linac

302

R.D. Porter, S. Aderhold, L.E. Alsberg, D. Gonnella, J. Nelson, N.R. Neveu, L.M. Zacarias
SLAC, Menlo Park, California, USA
A.T. Cravatta, J.P. Holzbauer, S. Posen
Fermilab, Batavia, Illinois, USA
M.A. Drury, M.D. McCaughan, C.M. Wilson
JLab, Newport News, Virginia, USA
G. Gaitan, N.A. Stilin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the LCLS-II project
The LCLS-II project has installed a new superconducting linac at SLAC that consists of 35 1.3 GHz cryomodules and 2 3.9 GHz cryomodules. The linac will provide a 4 GeV electron beam for generating soft and hard X-ray pulses. Cavity detuning induced by microphonics was a significant design challenge for the LCLS-II cryomodules. Cryomodules were produced that were within the detuning specification (10 Hz for 1.3 GHz cryomodules) on test stands. Here we present first measurements of the microphonics in the installed LCLS-II superconducting linac. Overall, the microphonics in the linac are manageable with 94% of cavities coming within the detune specification. Only two cavities are gradient limited due to microphonics. We identify a leaking cool down valve as the source of microphonics limiting those two cavities.

Poster MOPMB081 [1.284 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB081

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Received ※ 18 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 01 July 2023

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MOPMB090

Measuring Q₀ in LCLS-II Cryomodules Using Helium Liquid Level

327

L.M. Zacarias, S. Aderhold, D. Gonnella, J.T. Maniscalco, J. Nelson, R.D. Porter
SLAC, Menlo Park, California, USA
A.T. Cravatta, J.P. Holzbauer, S. Posen
Fermilab, Batavia, Illinois, USA
M.A. Drury, M.D. McCaughan, C.M. Wilson
JLab, Newport News, Virginia, USA

The nitrogen-doped cavities used in the Linac Coherent Light Source II (LCLS-II) cryomodules have shown an unprecedented high Q₀ in vertical and cryomodule testing compared with cavities prepared with standard methods. While demonstration of high Q₀ in the test stand has been achieved, maintaining that performance in the linac is critical to the success of LCLS-II and future accelerator projects. The LCLS-II cryomodules required a novel method of measuring Q₀, due to hardware incompatibilities with existing procedures. Initially developed at Jefferson Lab during cryomodule acceptance testing before being used in the tunnel at SLAC, we use helium liquid level data to estimate the heat generated by cavities. We first establish the relationship between the rate of helium evaporation from known heat loads using electric heaters, and then use that relationship to determine heat from an RF load. Here we present the full procedure along with the development process, lessons learned, and reproducibility while demonstrating for the first time that world record Q₀ can be maintained within the real accelerator environment.

Poster MOPMB090 [1.867 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB090

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Received ※ 20 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 13 July 2023

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TUPTB001

Demonstration of Niobium Tin in 218 MHz Low-Beta Quarter Wave Accelerator Cavity

388

T.B. Petersen, G. Chen, B.M. Guilfoyle, M. Kedzie, M.P. Kelly, T. Reid
ANL, Lemont, Illinois, USA
G.V. Eremeev, S. Posen, B. Tennis
Fermilab, Batavia, Illinois, USA

A 218 MHz quarter wave niobium cavity has been fabricated for the purpose of demonstrating Nb₃Sn technology on a low-beta accelerator cavity. Niobium-tin has been established as a promising next generation SRF material, but development has focused primarily in high-beta elliptical cell cavities. This material has a significantly higher TC than niobium, allowing for design of higher frequency quarter wave cavities (that are subsequently smaller) as well as for significantly lowered cooling requirements (possibly leading to cryocooler based de-signs). The fabrication, initial cold testing, and Nb₃Sn coating are discussed as well as test plans and details of future applications.

Poster TUPTB001 [0.653 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB001

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Received ※ 16 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 08 July 2023

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TUPTB010

Preservation of the High Quality Factor and Accelerating Gradient of Nb₃Sn-Coated Cavity During Pair Assembly

405

G.V. Eremeev, S. Cheban, S. Posen, B. Tennis
Fermilab, Batavia, Illinois, USA
J.F. Fischer, D. Forehand, U. Pudasaini, A.V. Reilly, R.A. Rimmer
JLab, Newport News, Virginia, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Two CEBAF 5-cell accelerator cavities have been coated with Nb₃Sn film using the vapor diffusion technique. One cavity was coated in the Jefferson Lab Nb₃Sn cavity coating system, and the other in the Fermilab Nb₃Sn coating system. Both cavities were measured at 4 K and 2 K in the vertical dewar test in each lab and then assembled into a cavity pair at Jefferson Lab. Previous attempts to assemble Nb₃Sn cavities into a cavity pair degraded the superconducting properties of Nb₃Sn-coated cavities. This contribution discusses the efforts to identify and mitigate the pair assembly challenges and will present the results of the vertical tests before and after pair assembly. Notably, one of the cavities reached the highest gradient above 80 mT in the vertical test after the pair assembly.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB010

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Received ※ 23 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 02 July 2023 — Issue date ※ 09 July 2023

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WEIXA07

Review of Thermal Treatments: Effects, Reliability, and Open Questions

S. Posen
Fermilab, Batavia, Illinois, USA

Over years of research and development, a variety of thermal treatments have been developed for bulk niobium cavities, providing different high performance capabilities for SRF resonators depending on the application. Key considerations include maximum field, quality factor at a desired field, sensitivity to trapped flux, and reproducibility of performance. In this talk, we overview the last decade of development of heat treatments, as well as what is reliability achieved at different laboratories, and open questions.

Slides WEIXA07 [6.423 MB]

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WEPWB109

PI Loop Resonance Control for the Dark Photon Experiment at 2 K using a 2.6 GHz SRF cavity

847

C. Contreras-Martinez, B. Giaccone, O.S. Melnychuk, A.V. Netepenko, Y.M. Pischalnikov, S. Posen, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Two 2.6 GHz cavities are being used for dark photon search at VTS in FNAL. During testing at 2 K the cavities experience frequency detuning caused by microphonics and slow frequency drifts. The experiment requires that the two cavities have the same frequency within 5 Hz. These two cavities are equipped with frequency tuners consisting of three piezo actuators. The piezo actuators are used for fine-fast frequency tuning. A PI loop utilizing the piezos was used to maintain both cavities at the same frequency, and the results are presented.

Poster WEPWB109 [1.151 MB]

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reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB109

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Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 18 July 2023

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WEPWB120

Flux Expulsion Testing for LCLS-II-HE Cavity Production

876

J.T. Maniscalco, S. Aderhold, M. Checchin, D. Gonnella, R.D. Porter
SLAC, Menlo Park, California, USA
T.T. Arkan, D. Bafia, J.A. Kaluzny, S. Posen
Fermilab, Batavia, Illinois, USA
M.E. Bevins, A.J. Grabowski, J. Hogan, C.E. Reece, D. Savransky, H. Vennekate
JLab, Newport News, VA, USA

Nitrogen-doped niobium SRF cavities are sensitive to trapped magnetic flux, which decreases the cavity intrinsic Q₀. Prior experimental results have shown that heat treatments to 900°C and higher can result in stronger flux expulsion during cooldown; the precise temperature required tends to vary by vendor lot/ingot of the niobium material used in the cavity cells. For LCLS-II-HE, to ensure sufficient flux expulsion in all cavities, we built and tested single-cell cavities to determine this required temperature for each vendor lot of niobium material to be used in cavity cells. In this report, we present the results of the single-cell flux expulsion testing and the Q₀ of the nine-cell cavities built using the characterized vendor lots. We discuss mixing material from different vendor lots, examine the lessons learned, and finally present an outlook on possible refinements to the single-cell technique.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB120

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Received ※ 15 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 13 July 2023

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WEPWB133

Testing of the 2.6 GHz SRF Cavity Tuner for the Dark Photon Experiment at 2 K

907

C. Contreras-Martinez, B. Giaccone, I.V. Gonin, T.N. Khabiboulline, O.S. Melnychuk, Y.M. Pischalnikov, S. Posen, O.V. Pronitchev, J.C. Yun
Fermilab, Batavia, Illinois, USA

At FNAL two 2.6 GHz SRF cavities are being used to search for dark photons, the experiment can be conducted at 2 K or in a dilution refrigerator. Precise frequency tuning is required for these two cavities so they can be matched in frequency. A cooling capacity constraint on the dilution refrigerator only allows piezo actuators to be part of the design of the 2.6 GHz cavity tuner. The tuner is equipped with three encapsulated piezo that deliver the long- and short-range frequency tuning. Modifications were implemented on the first tuner design due to the low forces on the piezos due to the cavity. Three brass rods with Belleville washers were added to the design to increase the overall force on the piezos. The results at 2 K of testing this tuner with and without the modification will be presented.

Poster WEPWB133 [0.829 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB133

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Received ※ 16 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 04 July 2023

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THIXA06

Dark Matter and Gravitational Waves Experiments with SRF Cavities

B. Giaccone, A. Grassellino, S. Posen, A.S. Romanenko
Fermilab, Batavia, Illinois, USA

Funding: This material is based upon work supported by the U.S. DOE, SC, National QIS Research Centers, Superconducting Quantum Materials and Systems Center (SQMS) under contract n. DE-AC02-07CH11359
Recent efforts have shown that the SRF technology developed for accelerators can be successfully applied to new applications, including quantum computing, dark matter searches and beyond the standard model physics. The ultra-high quality factor of SRF cavities can allow to achieve unprecedented sensitivity in fields outside of the usual accelerator applications, for examples in dark photon and axion searches (both as dark matter candidates and lab-produced particles). Applications of SRF cavities for gravitational waves searches are also being investigated. The SQMS Physics and Sensing thrust is leveraging SRF cavities and QIS to search for new particles and BSM physics. This talk will highlight experiments where SRF cavities have already set experimental bounds on new physics.

Slides THIXA06 [5.984 MB]

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