SRF2023 - List of Keywords (polarization)

Paper	Title	Other Keywords	Page
MOPMB005	Muon Spin Rotation Studies of Bilayer Superconductors and Low Temperature Baked Niobium	interface, experiment, cavity, niobium	62
	M. Asaduzzaman, R.E. Laxdal, R.M.L. McFadden, E. Thoeng TRIUMF, Vancouver, Canada M. Asaduzzaman, T. Junginger, R.M.L. McFadden UVIC, Victoria, Canada E. Thoeng UBC & TRIUMF, Vancouver, British Columbia, Canada
	Funding: Financial support was provided by an Natural Sciences and Engineering Research Council of Canada (NSERC) Muon spin rotation (muSR) results have shown that vortex penetration into Nb can be delayed up to the superheating field Hsh by a single layer of a material with larger London penetration depth. For low temperature baked (LTB) Nb an increase in the vortex penetration field Hvp has also been observed. While clearly exceeding the lower critical field Hc1, Hvp was found to remain significantly below Hsh for LTB niobium (Superconductor Science and Technology 30 (12), 125012). Further, magnetometry experiments suggested that there is no interface barrier in LTB Nb and that the apparent Hvp increase as observed by muSR was due to surface pinning (Scientific Reports 12 (1), 5522). By varying the implantation depth of ~4.1 MeV muons using moderating foils, new muSR measurements confirm that the apparent Hvp increase in LTB Nb is indeed due to surface pinning, while for a Nb₃Sn/Nb bilayer we find an interface barrier for flux penetration. These results confirm the potential of using superconducting bilayers to achieve a flux free Meissner state up to the superheating field of the substrate.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB005
About •	Received ※ 17 June 2023 — Revised ※ 21 June 2023 — Accepted ※ 25 June 2023 — Issue date ※ 21 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUIXA04	First Results from beta-SRF- Testing SRF Samples at High Parallel Field	SRF, experiment, niobium, ISAC	374
	E. Thoeng, R. Kiefl, W.A. MacFarlane, J.O. Ticknor UBC & TRIUMF, Vancouver, British Columbia, Canada M. Asaduzzaman, S.R. Dunsiger, D. Fujimoto, T. Junginger, V.L. Karner, P. Kolb, R.E. Laxdal, R. Li, R.M.L. McFadden, G. Morris, M. Stachura TRIUMF, Vancouver, Canada T. Junginger, R.M.L. McFadden UVIC, Victoria, Canada
	The new ¿-SRF facility at TRIUMF has recently been commissioned. A new 1 m extension has been added to an existing ¿-NMR beamline with a large Helmholtz coil to produce fields up to 200 mT parallel to sample surfaces. The ¿-NMR technique allows depth dependent characterization of the local magnetic field in the first 100 nm of the sample surface making the probe ideal for studying Meissner screen- ing in heat treated Niobium or layered SRF materials. First measurements of Meissner screening at fields up to 200 mT have been analyzed. The results show clear differences in the Meissner screening of baseline treatments compared to mid-T baked (O-doped) Niobium.
	Slides TUIXA04 [1.644 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUIXA04
About •	Received ※ 24 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 06 July 2023 — Issue date ※ 09 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB042	Latest Development of Electropolishing Optimization for 650 MHz Cavity	cavity, cathode, SRF, niobium	512
	V. Chouhan, D.J. Bice, D.A. Burk, S.K. Chandrasekaran, A.T. Cravatta, P.F. Dubiel, G.V. Eremeev, F. Furuta, O.S. Melnychuk, A.V. Netepenko, M.K. Ng, J.P. Ozelis, H. Park, T.J. Ring, G. Wu Fermilab, Batavia, Illinois, USA B.M. Guilfoyle, M.P. Kelly, T. Reid ANL, Lemont, Illinois, USA
	Electropolishing (EP) of 1.3 GHz niobium (Nb) superconducting RF cavities is conducted to achieve a desired smooth and contaminant-free surface that yields good RF performance. Achieving a smooth surface of a large-sized elliptical cavity with the standard EP conditions was found to be challenging. This work aimed to conduct a systematic parametric EP study to understand the effects of various EP parameters on the surface of 650 MHz cavities used in PIP-II linac. Parameters optimized in this study provided a smooth surface of the cavities. The electropolished cavities met the baseline requirement of field gradient and qualified for further surface treatment to improve the cavity quality factor.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB042
About •	Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 06 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOPMB005

Muon Spin Rotation Studies of Bilayer Superconductors and Low Temperature Baked Niobium

interface, experiment, cavity, niobium

62

M. Asaduzzaman, R.E. Laxdal, R.M.L. McFadden, E. Thoeng
TRIUMF, Vancouver, Canada
M. Asaduzzaman, T. Junginger, R.M.L. McFadden
UVIC, Victoria, Canada
E. Thoeng
UBC & TRIUMF, Vancouver, British Columbia, Canada

Funding: Financial support was provided by an Natural Sciences and Engineering Research Council of Canada (NSERC)
Muon spin rotation (muSR) results have shown that vortex penetration into Nb can be delayed up to the superheating field Hsh by a single layer of a material with larger London penetration depth. For low temperature baked (LTB) Nb an increase in the vortex penetration field Hvp has also been observed. While clearly exceeding the lower critical field Hc1, Hvp was found to remain significantly below Hsh for LTB niobium (Superconductor Science and Technology 30 (12), 125012). Further, magnetometry experiments suggested that there is no interface barrier in LTB Nb and that the apparent Hvp increase as observed by muSR was due to surface pinning (Scientific Reports 12 (1), 5522). By varying the implantation depth of ~4.1 MeV muons using moderating foils, new muSR measurements confirm that the apparent Hvp increase in LTB Nb is indeed due to surface pinning, while for a Nb₃Sn/Nb bilayer we find an interface barrier for flux penetration. These results confirm the potential of using superconducting bilayers to achieve a flux free Meissner state up to the superheating field of the substrate.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB005

About •

Received ※ 17 June 2023 — Revised ※ 21 June 2023 — Accepted ※ 25 June 2023 — Issue date ※ 21 July 2023

Cite •

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

TUIXA04

First Results from beta-SRF- Testing SRF Samples at High Parallel Field

SRF, experiment, niobium, ISAC

374

E. Thoeng, R. Kiefl, W.A. MacFarlane, J.O. Ticknor
UBC & TRIUMF, Vancouver, British Columbia, Canada
M. Asaduzzaman, S.R. Dunsiger, D. Fujimoto, T. Junginger, V.L. Karner, P. Kolb, R.E. Laxdal, R. Li, R.M.L. McFadden, G. Morris, M. Stachura
TRIUMF, Vancouver, Canada
T. Junginger, R.M.L. McFadden
UVIC, Victoria, Canada

The new ¿-SRF facility at TRIUMF has recently been commissioned. A new 1 m extension has been added to an existing ¿-NMR beamline with a large Helmholtz coil to produce fields up to 200 mT parallel to sample surfaces. The ¿-NMR technique allows depth dependent characterization of the local magnetic field in the first 100 nm of the sample surface making the probe ideal for studying Meissner screen- ing in heat treated Niobium or layered SRF materials. First measurements of Meissner screening at fields up to 200 mT have been analyzed. The results show clear differences in the Meissner screening of baseline treatments compared to mid-T baked (O-doped) Niobium.

Slides TUIXA04 [1.644 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUIXA04

About •

Received ※ 24 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 06 July 2023 — Issue date ※ 09 July 2023

Cite •

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

TUPTB042

Latest Development of Electropolishing Optimization for 650 MHz Cavity

cavity, cathode, SRF, niobium

512

V. Chouhan, D.J. Bice, D.A. Burk, S.K. Chandrasekaran, A.T. Cravatta, P.F. Dubiel, G.V. Eremeev, F. Furuta, O.S. Melnychuk, A.V. Netepenko, M.K. Ng, J.P. Ozelis, H. Park, T.J. Ring, G. Wu
Fermilab, Batavia, Illinois, USA
B.M. Guilfoyle, M.P. Kelly, T. Reid
ANL, Lemont, Illinois, USA

Electropolishing (EP) of 1.3 GHz niobium (Nb) superconducting RF cavities is conducted to achieve a desired smooth and contaminant-free surface that yields good RF performance. Achieving a smooth surface of a large-sized elliptical cavity with the standard EP conditions was found to be challenging. This work aimed to conduct a systematic parametric EP study to understand the effects of various EP parameters on the surface of 650 MHz cavities used in PIP-II linac. Parameters optimized in this study provided a smooth surface of the cavities. The electropolished cavities met the baseline requirement of field gradient and qualified for further surface treatment to improve the cavity quality factor.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB042

About •

Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 06 July 2023

Cite •

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