IPAC2021 - Classification: MC7: Accelerator Technology / T20 Targetry

Paper	Title	Page
WEPAB363	Dynamic Response of Spallation Volume to Beam Raster on the European Spallation Source Target	3552
	Y. Lee ESS, Lund, Sweden
	To achieve a desirably low beam intensity on the target, the European Spallation Source (ESS) adopted a beam raster system at the high beta beam transport part of the linac. The raster system paints the beam on the target with frequencies up to 40 kHz within the 2.86 ms beam pulse, to form a uniformly expanded beam footprint. While the beam raster reduces the time-averaged beam current density to a level that the 5 years of design lifetime of the target system can be achieved with a high operational reliability, it could potentially induce deleterious dynamic excitations in the spallation volume made of tungsten. The stress wavelets created by raster sweeps can be amplified if the sweep frequency is in tune with a resonance mode of the tungsten volume. This coherent interference of the wavelets could lead to a high dynamic stress in tungsten, posing a risk of premature failure of the target. In this paper, the dynamic response of the spallation volume of the ESS target to different beam raster frequencies has been analysed, using multi-physics simulations based on measured material data. Finally, a safe operational range of the beam raster frequency band is proposed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB363
About •	paper received ※ 12 May 2021 paper accepted ※ 02 July 2021 issue date ※ 01 September 2021
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WEPAB364	Third-Generation CERN n_TOF Spallation Target: Final Design and Examinations of Irradiated Prototype	3555
	R. Esposito, O. Aberle, M. Calviani, T. Coiffet, M.D. Crouvizier, R. Franqueira Ximenes, V. Maire, A.T. Perez Fontenla, M.A. Timmins CERN, Geneva, Switzerland
	The new neutron spallation target for the CERN neutron Time-Of-Flight (n_TOF) facility is based on a nitrogen-cooled Pb core impacted by short high-intensity proton beam pulses. An extensive material characterization campaign has been carried out to define the constitutive behavior of lead and assess its response under pulsed proton beam irradiation. The activities carried out include a beam irradiation test in the CERN HiRadMat facility. The tests and inspections performed show a robust behavior of the core material during operation and prominent static hardening recovery already at room temperature.
	Poster WEPAB364 [1.011 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB364
About •	paper received ※ 18 May 2021 paper accepted ※ 11 June 2021 issue date ※ 20 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB365	CERN BDF Prototype Target Operation, Removal and Autopsy Steps	3559
	R. Franqueira Ximenes, O. Aberle, C. Ahdida, P. Avigni, M. Battistin, L. Bianchi, L.R. Buonocore, S. Burger, J. Busom, M. Calviani, J.P. Canhoto Espadanal, M. Casolino, M. Di Castro, M.A. Fraser, S.S. Gilardoni, S. Girod, J.L. Grenard, D. Grenier, M. Guinchard, R. Jacobsson, M. Lamont, E. Lopez Sola, A. Ortega Rolo, A. Perillo-Marcone, Y. Pira, B. Riffaud, V. Vlachoudis, L. Zuccalli CERN, Meyrin, Switzerland
	The Beam Dump Facility (BDF), currently in the study phase, is a proposed general-purpose fixed target facility at CERN. Initially will host the Search for Hidden Particles (SHiP) experiment, intended to investigate the origin of dark matter and other weakly interacting particles. The BDF particle production target is located at the core of the facility and is employed to fully absorb the high intensity (400 GeV/c) Super Proton Synchrotron (SPS) beam. To validate the design of the production target, a downscaled prototype was tested with the beam at CERN in 2018 in the North Area primary area in a dedicated test at 35 kW average beam power. This contribution details the BDF prototype target operation, fully remote removal intervention, and foreseen post-irradiation examination plans.
	Poster WEPAB365 [1.691 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB365
About •	paper received ※ 18 May 2021 paper accepted ※ 15 June 2021 issue date ※ 25 August 2021
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WEPAB366	Towards the Last Stages of the CERN’s AD-Target Area Consolidation Project and Recommissioning Plans to Resume Operation	3563
	C. Torregrosa, C. Ahdida, A. Bouvard, A. Broche, S. Burger, M.E.J. Butcher, M. Calviani, V. Clerc, A. De Macedo, S. De Man, F.A. Deslande, M. Di Castro, T. Dobers, T. Feniet, R. Ferriere, E. Fornasiere, R. Franqueira Ximenes, T.J. Giles, J.L. Grenard, E. Grenier-Boley, G. Gräwer, M. Guinchard, M.D. Jedrychowski, K. Kershaw, B. Lefort, E. Lopez Sola, J.M. Martin Ruiz, A. Martínez Sellés, G. Matulenaite, C.Y. Mucher, A. Newborough, M. Perez Ornedo, E. Perez-Duenas, A. Perillo-Marcone, L. Ponce, N. Solieri, M.B. Szewczyk, P.A. Thonet, M.A. Timmins, A. Tursun, W. Van den Broucke, F.M. Velotti, C. Vendeuvre, V. Vlachoudis CERN, Meyrin, Switzerland J.C. Espadanal LIP, Lisboa, Portugal
	Antiprotons are produced at CERN at the Antiproton Decelerator (AD) Target Area by impacting 26 GeV/c proton beams onto a fixed target. Further collection, momentum selection, and transport of the secondary particles - including antiprotons - towards the AD ring is realised by a 400 kA pulsed magnetic horn and a set of magnetic dipoles and quadrupoles. A major consolidation of the area - in operation since the 80s - has taken place during the CERN Long Shutdown 2 (2019-2021). Among other activities, such upgrade included: (i) Installation of a new air-cooled target design and manufacturing of a new batch of magnetic horns, including a surface pulsing test-bench for their validation and fine-tuning (ii) Installation of a new positioning and maintenance system for the target and horn (iii) Refurbishment and decontamination of the Target Area and its equipment, (iv) Construction of a new surface service building to house new nuclear ventilation systems. This contribution presents an overview of such activities and lesson learnt. In addition, it provides the latest results from refractory metals R&D for the antiproton target and a summary of the recommissioning and optimization plans.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB366
About •	paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 01 September 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB367	Bubble Generation in the SNS 2 MW Mercury Target	3567
	C.N. Barbier, M.P. Costa, K.C. Johns, D. Ottinger, F. Rasheed, B.W. Riemer, R.L. Sangrey, J.R. Weinmeister, D.E. Winder ORNL, Oak Ridge, Tennessee, USA
	The accelerator at the Spallation Neutron Source is currently being upgraded to increase the proton beam power from 1.4 MW to 2.8 MW. About 2 MW will go to the first target station, while the rest will go to the future second target station. The first target station uses a mercury target. When the short proton beam pulse hits it, strong pressure waves are developed inside the mercury and the vessel itself, causing weld failures and cavitation erosion. The pressure wave can be significantly mitigated by injecting small helium bubbles into the mercury. SNS has been injecting helium since 2017 using small orifices but has met challenges in fabrication and operations with them. Thus, for the 2 MW target, swirl bubblers will be used to increase gas injection and improve reliability. A 2 MW prototypical target was built and tested in a mercury process loop available at Oak Ridge National Laboratory. Acrylic viewports on the top of the target were used to determine the bubble size distribution (BSD) generated by the swirl bubblers. It was found that the bubblers were not only capable of generating small bubbles but that the BSD was independent of gas injection rate.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB367
About •	paper received ※ 10 May 2021 paper accepted ※ 22 June 2021 issue date ※ 20 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB368	Sigraflex® Studies for LHC CERN Beam Dump: Summary and Perspective	3571
	J.M. Heredia, M. Calviani, R. Franqueira Ximenes, D. Grenier, K. Kershaw, A. Lechner, P. Andreu-Muñoz, F.-X. Nuiry, A. Perillo-Marcone, V. Rizzoglio, C. Torregrosa CERN, Geneva 23, Switzerland A. Alvaro SINTEF, Trondheim, Norway F. Berto, S. Solfiti NTNU, Trondheim, Norway
	The Large Hadron Collider (LHC) beam dump (TDE) is essential for safe and reliable operation of the collider. It absorbs particles extracted from the accelerator whenever required. The original design of the TDE dates from the mid 2000 and it is constituted of an eight-meter-long cylindrical stainless-steel tube, filled with low-Z carbon-based materials from different grades and densities. The Sigraflex®, an expanded low-density graphite, is employed in the middle section of the TDE core. Due to unexpected behaviour observed in the past LHC runs, several major upgrades were recently implemented in order for the TDE to be ready for LHC Run3 (2021-2024), where up to 555 MJ beam energy is expected to be dumped every few hours. According simulations, temperatures in the Sigraflex core will reach locally up to 1500°C in the regular dump cases, and above 2300°C for failure scenarios. The objective of this contribution is to summarize the LS2 hardware upgrades and the plan for the evaluation of the Sigraflex performance during LHC Run3. This work will also detail the last experimental and numerical findings applied to the Sigraflex®, and possible alternative materials for the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB368
About •	paper received ※ 18 May 2021 paper accepted ※ 11 August 2021 issue date ※ 16 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THXC03	Evolution of the High-Power Spallation Neutron Mercury Target at the SNS	3735
	D.E. Winder ORNL, Oak Ridge, Tennessee, USA
	Funding: UT-Battelle, LLC, under Grant DE-AC05-00OR22725 with the US Department of Energy (DOE). The Spallation Neutron Source (SNS) began operation in 2006 and first operated at its full 1.4 MW power in 2013. Targets, which receive the pulsed proton beam, were a limiting factor for reliable full power operation for several years. Reaching reliable target operation at 1.4 MW required not only changes to the target design but also support and coordination across the entire SNS enterprise. The history and some key lessons learned are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXC03
About •	paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 01 September 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Dynamic Response of Spallation Volume to Beam Raster on the European Spallation Source Target

3552

Y. Lee
ESS, Lund, Sweden

To achieve a desirably low beam intensity on the target, the European Spallation Source (ESS) adopted a beam raster system at the high beta beam transport part of the linac. The raster system paints the beam on the target with frequencies up to 40 kHz within the 2.86 ms beam pulse, to form a uniformly expanded beam footprint. While the beam raster reduces the time-averaged beam current density to a level that the 5 years of design lifetime of the target system can be achieved with a high operational reliability, it could potentially induce deleterious dynamic excitations in the spallation volume made of tungsten. The stress wavelets created by raster sweeps can be amplified if the sweep frequency is in tune with a resonance mode of the tungsten volume. This coherent interference of the wavelets could lead to a high dynamic stress in tungsten, posing a risk of premature failure of the target. In this paper, the dynamic response of the spallation volume of the ESS target to different beam raster frequencies has been analysed, using multi-physics simulations based on measured material data. Finally, a safe operational range of the beam raster frequency band is proposed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB363

About •

paper received ※ 12 May 2021 paper accepted ※ 02 July 2021 issue date ※ 01 September 2021

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

WEPAB364

Third-Generation CERN n_TOF Spallation Target: Final Design and Examinations of Irradiated Prototype

3555

R. Esposito, O. Aberle, M. Calviani, T. Coiffet, M.D. Crouvizier, R. Franqueira Ximenes, V. Maire, A.T. Perez Fontenla, M.A. Timmins
CERN, Geneva, Switzerland

The new neutron spallation target for the CERN neutron Time-Of-Flight (n_TOF) facility is based on a nitrogen-cooled Pb core impacted by short high-intensity proton beam pulses. An extensive material characterization campaign has been carried out to define the constitutive behavior of lead and assess its response under pulsed proton beam irradiation. The activities carried out include a beam irradiation test in the CERN HiRadMat facility. The tests and inspections performed show a robust behavior of the core material during operation and prominent static hardening recovery already at room temperature.

Poster WEPAB364 [1.011 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB364

About •

paper received ※ 18 May 2021 paper accepted ※ 11 June 2021 issue date ※ 20 August 2021

Export •

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

WEPAB365

CERN BDF Prototype Target Operation, Removal and Autopsy Steps

3559

R. Franqueira Ximenes, O. Aberle, C. Ahdida, P. Avigni, M. Battistin, L. Bianchi, L.R. Buonocore, S. Burger, J. Busom, M. Calviani, J.P. Canhoto Espadanal, M. Casolino, M. Di Castro, M.A. Fraser, S.S. Gilardoni, S. Girod, J.L. Grenard, D. Grenier, M. Guinchard, R. Jacobsson, M. Lamont, E. Lopez Sola, A. Ortega Rolo, A. Perillo-Marcone, Y. Pira, B. Riffaud, V. Vlachoudis, L. Zuccalli
CERN, Meyrin, Switzerland

The Beam Dump Facility (BDF), currently in the study phase, is a proposed general-purpose fixed target facility at CERN. Initially will host the Search for Hidden Particles (SHiP) experiment, intended to investigate the origin of dark matter and other weakly interacting particles. The BDF particle production target is located at the core of the facility and is employed to fully absorb the high intensity (400 GeV/c) Super Proton Synchrotron (SPS) beam. To validate the design of the production target, a downscaled prototype was tested with the beam at CERN in 2018 in the North Area primary area in a dedicated test at 35 kW average beam power. This contribution details the BDF prototype target operation, fully remote removal intervention, and foreseen post-irradiation examination plans.

Poster WEPAB365 [1.691 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB365

About •

paper received ※ 18 May 2021 paper accepted ※ 15 June 2021 issue date ※ 25 August 2021

Export •

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

WEPAB366

Towards the Last Stages of the CERN’s AD-Target Area Consolidation Project and Recommissioning Plans to Resume Operation

3563

C. Torregrosa, C. Ahdida, A. Bouvard, A. Broche, S. Burger, M.E.J. Butcher, M. Calviani, V. Clerc, A. De Macedo, S. De Man, F.A. Deslande, M. Di Castro, T. Dobers, T. Feniet, R. Ferriere, E. Fornasiere, R. Franqueira Ximenes, T.J. Giles, J.L. Grenard, E. Grenier-Boley, G. Gräwer, M. Guinchard, M.D. Jedrychowski, K. Kershaw, B. Lefort, E. Lopez Sola, J.M. Martin Ruiz, A. Martínez Sellés, G. Matulenaite, C.Y. Mucher, A. Newborough, M. Perez Ornedo, E. Perez-Duenas, A. Perillo-Marcone, L. Ponce, N. Solieri, M.B. Szewczyk, P.A. Thonet, M.A. Timmins, A. Tursun, W. Van den Broucke, F.M. Velotti, C. Vendeuvre, V. Vlachoudis
CERN, Meyrin, Switzerland
J.C. Espadanal
LIP, Lisboa, Portugal

Antiprotons are produced at CERN at the Antiproton Decelerator (AD) Target Area by impacting 26 GeV/c proton beams onto a fixed target. Further collection, momentum selection, and transport of the secondary particles - including antiprotons - towards the AD ring is realised by a 400 kA pulsed magnetic horn and a set of magnetic dipoles and quadrupoles. A major consolidation of the area - in operation since the 80s - has taken place during the CERN Long Shutdown 2 (2019-2021). Among other activities, such upgrade included: (i) Installation of a new air-cooled target design and manufacturing of a new batch of magnetic horns, including a surface pulsing test-bench for their validation and fine-tuning (ii) Installation of a new positioning and maintenance system for the target and horn (iii) Refurbishment and decontamination of the Target Area and its equipment, (iv) Construction of a new surface service building to house new nuclear ventilation systems. This contribution presents an overview of such activities and lesson learnt. In addition, it provides the latest results from refractory metals R&D for the antiproton target and a summary of the recommissioning and optimization plans.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB366

About •

paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 01 September 2021

Export •

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

WEPAB367

Bubble Generation in the SNS 2 MW Mercury Target

3567

C.N. Barbier, M.P. Costa, K.C. Johns, D. Ottinger, F. Rasheed, B.W. Riemer, R.L. Sangrey, J.R. Weinmeister, D.E. Winder
ORNL, Oak Ridge, Tennessee, USA

The accelerator at the Spallation Neutron Source is currently being upgraded to increase the proton beam power from 1.4 MW to 2.8 MW. About 2 MW will go to the first target station, while the rest will go to the future second target station. The first target station uses a mercury target. When the short proton beam pulse hits it, strong pressure waves are developed inside the mercury and the vessel itself, causing weld failures and cavitation erosion. The pressure wave can be significantly mitigated by injecting small helium bubbles into the mercury. SNS has been injecting helium since 2017 using small orifices but has met challenges in fabrication and operations with them. Thus, for the 2 MW target, swirl bubblers will be used to increase gas injection and improve reliability. A 2 MW prototypical target was built and tested in a mercury process loop available at Oak Ridge National Laboratory. Acrylic viewports on the top of the target were used to determine the bubble size distribution (BSD) generated by the swirl bubblers. It was found that the bubblers were not only capable of generating small bubbles but that the BSD was independent of gas injection rate.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB367

About •

paper received ※ 10 May 2021 paper accepted ※ 22 June 2021 issue date ※ 20 August 2021

Export •

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

WEPAB368

Sigraflex® Studies for LHC CERN Beam Dump: Summary and Perspective

3571

J.M. Heredia, M. Calviani, R. Franqueira Ximenes, D. Grenier, K. Kershaw, A. Lechner, P. Andreu-Muñoz, F.-X. Nuiry, A. Perillo-Marcone, V. Rizzoglio, C. Torregrosa
CERN, Geneva 23, Switzerland
A. Alvaro
SINTEF, Trondheim, Norway
F. Berto, S. Solfiti
NTNU, Trondheim, Norway

The Large Hadron Collider (LHC) beam dump (TDE) is essential for safe and reliable operation of the collider. It absorbs particles extracted from the accelerator whenever required. The original design of the TDE dates from the mid 2000 and it is constituted of an eight-meter-long cylindrical stainless-steel tube, filled with low-Z carbon-based materials from different grades and densities. The Sigraflex®, an expanded low-density graphite, is employed in the middle section of the TDE core. Due to unexpected behaviour observed in the past LHC runs, several major upgrades were recently implemented in order for the TDE to be ready for LHC Run3 (2021-2024), where up to 555 MJ beam energy is expected to be dumped every few hours. According simulations, temperatures in the Sigraflex core will reach locally up to 1500°C in the regular dump cases, and above 2300°C for failure scenarios. The objective of this contribution is to summarize the LS2 hardware upgrades and the plan for the evaluation of the Sigraflex performance during LHC Run3. This work will also detail the last experimental and numerical findings applied to the Sigraflex®, and possible alternative materials for the future.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB368

About •

paper received ※ 18 May 2021 paper accepted ※ 11 August 2021 issue date ※ 16 August 2021

Export •

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THXC03

Evolution of the High-Power Spallation Neutron Mercury Target at the SNS

3735

D.E. Winder
ORNL, Oak Ridge, Tennessee, USA

Funding: UT-Battelle, LLC, under Grant DE-AC05-00OR22725 with the US Department of Energy (DOE).
The Spallation Neutron Source (SNS) began operation in 2006 and first operated at its full 1.4 MW power in 2013. Targets, which receive the pulsed proton beam, were a limiting factor for reliable full power operation for several years. Reaching reliable target operation at 1.4 MW required not only changes to the target design but also support and coordination across the entire SNS enterprise. The history and some key lessons learned are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXC03

About •

paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 01 September 2021

Export •

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