IPAC2011 - Classification: 07 Accelerator Technology / T19 Collimation

Paper

Title

Page

Overview of EuCARD Accelerator and Material Research at GSI

1602

J. Stadlmann, H. Kollmus, E. Mustafin, N. Pyka, P.J. Spiller, I. Strašík, N.A. Tahir, M. Tomut, C. Trautmann
GSI, Darmstadt, Germany
L.H.J. Bozyk
TU Darmstadt, Darmstadt, Germany

Funding: EuCARD is co-funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 227579
EuCARD is a joined accelerator R&D initiative funded by the EU. Within this program, GSI Darmstadt is performing R&D on materials for accelerators and collimators in WP8(ColMat). GSI covers prototyping and testing of a cryogenic ion catcher for FAIR's main synchrotron SIS100, simulations and studies on activation of accelerator components e.g. halo collimatiors as well as irradiation experiments on materials foreseen to be used in FAIR accelerators and the LHC upgrade program. Carbon-carbon composites, silicon carbide and copper-diamond composite samples have been irradiated with heavy ions at various GSI beamlines and their radiation induced property changes were characterized. Numerical simulations on the possible damage by LHC and SPS beams to different targets have been performed. Simulations and modelling of activation and long term radiation induced damage to accelerator components have started. A prototype ion catcher has been built and first experiments have been performed in 2011. New collaborations with other institutes and industry in the EuCARD framework have been established and findings of the joined R&D effort influence decisions in the FAIR project and LHC upgrade.

TUPS033

Foil Scattering Loss Mitigation by the Additional Collimation System of J-PARC RCS

1605

K. Yamamoto, H. Harada, J. Kamiya, Y. Yamazaki, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

In the RCS, the significant losses were observed at the branch of H0 dump line and the Beam Position Monitor which was put at the downstream of the H0 dump branch duct. From the beam study, we were certain that these losses were caused by the scattering of the injection and circulating beam at the charge exchange injection foil. In order to mitigate these losses, we started to develop a new collimation system in the H0 branch duct. We presents a overview of this new collimation system.

TUPS034

Development and Construction of the Beam Dump for J-PARC Hadron Hall

1608

A. Agari, E. Hirose, M. Ieiri, Y. Katoh, M. Minakawa, R. Muto, M. Naruki, Y. Sato, S. Sawada, Y. Shirakabe, Y. Suzuki, H. Takahashi, M. Takasaki, K.H. Tanaka, A. Toyoda, H. Watanabe, Y. Yamanoi
KEK, Tsukuba, Japan
H. Noumi
RCNP, Osaka, Japan

Funding: This work is supported by Grant-in-Aid (No.22740184) for Young Scientists (B) of the Japan Ministry of Education, Culture, Sports, Science and Technology [MEXT].
A facility of Hadron hall at Japan Proton Accelerator Research Complex (J-PARC) had been constructed in June 2007. Hadron hall is designed to handle intense slow-extraction proton beam from the main accelerator of J-PARC, i.e. 50-GeV-PS. The first transportation of the proton beam to the hall was successfully made in Jan. 2009. A beam dump constructed at the end of the primary proton beam line in Hadron hall is designed to safely absorb 15 μA (=750-kW) proton beam. Its central core of the dump is made of copper with water cooling and is surrounded by iron and concrete for radiation protection. We made thermal and mechanical FEM analysis for investigating heat generation and mechanical stress from energy deposition. We also made cooling experiments for measuring heat transfer coefficient of candidates for new cooling device. As a result, the adopted device has direct cooling paths which are prepared as long holes made by Gun Drill from the outer surface of the copper core. In addition, the beam dump is designed to safely move to 50-m downstream as one body for future expansion of Hadron hall. This paper reports development and construction of the beam dump in Hadron hall.

TUPS035

LHC Collimators with Embedded Beam Position Monitors: A New Advanced Mechanical Design

1611

A. Dallocchio, A. Bertarelli, C.B. Boccard, F. Carra, M. Gasior, L. Gentini, M.A. Timmins
CERN, Geneva, Switzerland

The LHC collimation system, ensuring both functions of beam cleaning and machine protection, is potentially submitted to high-energy beam impacts. Currently the collimators setup is performed by monitoring beam losses generated by the collimator jaws when approaching the particle beam. This procedure is applied to all LHC collimators (almost one hundred), taking several hours, and needs to be repeated if beam settings change significantly. Furthermore, during the beam-based alignment, the LHC tertiary collimators are potentially exposed to abnormal losses entailing possible damage to their tungsten jaws. To improve the efficiency of the machine operation and better control the particle beam a new advanced design embedding Beam Position Monitors (BPM) into the movable collimator jaws has been developed. This paper describes the mechanical design of various types of future collimators with embedded BPMs. Experimental measurements performed on a simplified functional prototype installed in the CERN SPS showed that, thanks to on-board BPMs, the collimator could be precisely, rapidly, and safely aligned and the beam position accurately measured.

TUPS037

Preliminary Assessment of Beam Impact Consequences on LHC Collimators

1617

M. Cauchi, R.W. Assmann, A. Bertarelli, R. Bruce, F. Carra, A. Dallocchio, D. Deboy, N. Mariani, A. Rossi, N.J. Sammut
CERN, Geneva, Switzerland
M. Cauchi, P. Mollicone
UoM, Msida, Malta
L. Lari
IFIC, Valencia, Spain

The correct functioning of the LHC collimation system is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, the robustness of the collimators plays an important role. An accident which causes the proton beam to hit a collimator might result in severe beam-induced damage and, in some cases, replacement of the collimator, with consequent downtime for the machine. In this paper, several case studies representing different realistic beam impact scenarios are shown. A preliminary analysis of the thermal response of tertiary collimators to beam impact is presented, from which the most critical cases can be identified. Such work will also help to give an initial insight on the operational constraints of the LHC by taking into account all relevant collimator damage limits.

TUPS038

Design of a Beam Dump for 3 to 100 MeV for the New H⁻ Beam in the CERN Linac4

1620

C. Maglioni
CERN, Geneva, Switzerland

In this paper the design of a beam dump for the energy range from 3 to 100 MeV is reported. The dump is developed as temporary dump for the commissioning phase of the Linac4 Project, under construction at CERN, and will be installed in different periods to withstand a beam of different intensities and energies, following the chronological assembly of the linac. The dump design and its functionalities, as well as material choice, criticalities and cooling system are described. Finally, the results from the numerical and analytical thermo-mechanical analyses are reported, while the use of the dump also at 160 MeV is investigated.

TUPS039

Reduction of Magnetic Interference on the Position Sensors of the LHC Collimators

1623

A. Masi, M. Lamberti, R. Losito, M. Martino
CERN, Geneva, Switzerland

The jaws of the LHC collimators have to be positioned with respect to the beam with an accuracy of 20 μm. On some collimators, installed in the LHC transfer lines from SPS, huge reading errors of several tens of micrometers have been observed on the Linear Variable Differential Transformer (LVDT) positioning sensors in synchronization with the variable magnetic field produced by the feed cables of the pulsed resistive dipoles of the transfer line. In this paper we introduce and describe in detail the problem, the model developed using FLUXTM for the simulation of the magnetic flux density generated by the current cables in the complex environment of an LHC transfer line, and the magnetic shielding we designed and implemented. Finally, we compare the results of simulations with experimental measurements taken during on-line pulsed magnets test campaigns.

TUPS040

Driving the LHC Collimators' Stepping Motors over 1 km with High Accuracy avoiding EMI Effects

1626

A. Masi, G. Conte, R. Losito, M. Martino
CERN, Geneva, Switzerland

The LHC collimators are exposed to very high levels of radiation, which means that the power drivers must be installed far from the stepping motors that they drive. Due to the geometry of the underground installations, the distances can be up to 1 km. The long cables that connect the drivers to the motors behave as transmission lines modifying dramatically the impedance seen by the drivers and consequently jeopardizing the control performance of Pulse Width Modulation (PWM) drivers. In this paper we address this problem, provide an analytical model of the driver-cable-motor system and describe the analog solution we have developed to improve the performance of a typical off the shelf driver. Finally we characterize the improvement of the performances with measurements of positioning repeatability and show that electromagnetic emissions from the long cables are drastically reduced, making the use of stepping motors compatible with extremely sensitive instrumentation such as the LHC Beam Loss Monitors (BLM).

TUPS041

Thermo-mechanical Study of a CLIC Bunch Train hitting a Beryllium Energy Spoiler Model

1629

J.-L. Fernández-Hernando, D. Angal-Kalinin
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J. Resta-López
IFIC, Valencia, Spain

A thermo-mechanical study of the impact a CLIC bunch train has over a beryllium energy spoiler has been made. Beryllium has a high electrical and thermal conductivity which together with a large radiation length compared to other metals makes it an optimal candidate for a long tapered design spoiler that will not generate high wakefields, which might degrade the orbit stability and affect the collider luminosity. This paper shows the progress made from the paper presented last year in IPAC 2010. While in the aforementioned paper the study of the temperature and stress was made for the duration of the bunch train this time the study shows the evolution of the stress in the spoiler body 3 microseconds after the bunch train hit.

TUPZ011

LHC Collimation with a Reduced Beam Pipe Radius in ATLAS

1822

R. Bruce, R.W. Assmann
CERN, Geneva, Switzerland

Based on SixTrack simulations, we investigate the effect from collimation of a reduced beam pipe in the ATLAS experiment in the LHC. Several running scenarios are studied with range of different beam pipe radii and in each case we conclude on the minimum allowed aperture, which does not cause beam losses inside the detectors.

THOBB03

Research and Development of Novel Advanced Materials for Next-generation Collimators

2888

A. Bertarelli, G. Arnau-Izquierdo, F. Carra, A. Dallocchio, M. Gil Costa, N. Mariani
CERN, Geneva, Switzerland

Funding: This work has partly been carried out through the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program.
The study of innovative collimators is essential to handle the high energy particle beams required to explore unknown territory in basic research. This calls for the development of novel advanced materials, as no existing metal-based or carbon-based material possesses the combination of physical, thermal, electrical and mechanical properties, imposed by collimator extreme working conditions. A new family of materials, with promising features, has been identified: metal-diamond composites. These materials are to combine the outstanding thermal and physical properties of diamond with the electrical and mechanical properties of metals. The best candidates are Copper-Diamond (Cu-CD) and Molybdenum-Diamond (Mo-CD). In particular, Mo-CD may provide interesting properties as to mechanical strength, melting temperature, thermal shock resistance and, thanks to its balanced material density, energy absorption. The research program carried out on these materials at CERN and collaborating partners is presented, mainly focusing on the theoretical investigation, material characterization, and manufacturing processes.

Slides THOBB03 [3.948 MB]

Paper	Title	Page
TUPS032	Overview of EuCARD Accelerator and Material Research at GSI	1602
	J. Stadlmann, H. Kollmus, E. Mustafin, N. Pyka, P.J. Spiller, I. Strašík, N.A. Tahir, M. Tomut, C. Trautmann GSI, Darmstadt, Germany L.H.J. Bozyk TU Darmstadt, Darmstadt, Germany
	Funding: EuCARD is co-funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 227579 EuCARD is a joined accelerator R&D initiative funded by the EU. Within this program, GSI Darmstadt is performing R&D on materials for accelerators and collimators in WP8(ColMat). GSI covers prototyping and testing of a cryogenic ion catcher for FAIR's main synchrotron SIS100, simulations and studies on activation of accelerator components e.g. halo collimatiors as well as irradiation experiments on materials foreseen to be used in FAIR accelerators and the LHC upgrade program. Carbon-carbon composites, silicon carbide and copper-diamond composite samples have been irradiated with heavy ions at various GSI beamlines and their radiation induced property changes were characterized. Numerical simulations on the possible damage by LHC and SPS beams to different targets have been performed. Simulations and modelling of activation and long term radiation induced damage to accelerator components have started. A prototype ion catcher has been built and first experiments have been performed in 2011. New collaborations with other institutes and industry in the EuCARD framework have been established and findings of the joined R&D effort influence decisions in the FAIR project and LHC upgrade.

TUPS033	Foil Scattering Loss Mitigation by the Additional Collimation System of J-PARC RCS	1605
	K. Yamamoto, H. Harada, J. Kamiya, Y. Yamazaki, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	In the RCS, the significant losses were observed at the branch of H0 dump line and the Beam Position Monitor which was put at the downstream of the H0 dump branch duct. From the beam study, we were certain that these losses were caused by the scattering of the injection and circulating beam at the charge exchange injection foil. In order to mitigate these losses, we started to develop a new collimation system in the H0 branch duct. We presents a overview of this new collimation system.

TUPS034	Development and Construction of the Beam Dump for J-PARC Hadron Hall	1608
	A. Agari, E. Hirose, M. Ieiri, Y. Katoh, M. Minakawa, R. Muto, M. Naruki, Y. Sato, S. Sawada, Y. Shirakabe, Y. Suzuki, H. Takahashi, M. Takasaki, K.H. Tanaka, A. Toyoda, H. Watanabe, Y. Yamanoi KEK, Tsukuba, Japan H. Noumi RCNP, Osaka, Japan
	Funding: This work is supported by Grant-in-Aid (No.22740184) for Young Scientists (B) of the Japan Ministry of Education, Culture, Sports, Science and Technology [MEXT]. A facility of Hadron hall at Japan Proton Accelerator Research Complex (J-PARC) had been constructed in June 2007. Hadron hall is designed to handle intense slow-extraction proton beam from the main accelerator of J-PARC, i.e. 50-GeV-PS. The first transportation of the proton beam to the hall was successfully made in Jan. 2009. A beam dump constructed at the end of the primary proton beam line in Hadron hall is designed to safely absorb 15 μA (=750-kW) proton beam. Its central core of the dump is made of copper with water cooling and is surrounded by iron and concrete for radiation protection. We made thermal and mechanical FEM analysis for investigating heat generation and mechanical stress from energy deposition. We also made cooling experiments for measuring heat transfer coefficient of candidates for new cooling device. As a result, the adopted device has direct cooling paths which are prepared as long holes made by Gun Drill from the outer surface of the copper core. In addition, the beam dump is designed to safely move to 50-m downstream as one body for future expansion of Hadron hall. This paper reports development and construction of the beam dump in Hadron hall.

TUPS035	LHC Collimators with Embedded Beam Position Monitors: A New Advanced Mechanical Design	1611
	A. Dallocchio, A. Bertarelli, C.B. Boccard, F. Carra, M. Gasior, L. Gentini, M.A. Timmins CERN, Geneva, Switzerland
	The LHC collimation system, ensuring both functions of beam cleaning and machine protection, is potentially submitted to high-energy beam impacts. Currently the collimators setup is performed by monitoring beam losses generated by the collimator jaws when approaching the particle beam. This procedure is applied to all LHC collimators (almost one hundred), taking several hours, and needs to be repeated if beam settings change significantly. Furthermore, during the beam-based alignment, the LHC tertiary collimators are potentially exposed to abnormal losses entailing possible damage to their tungsten jaws. To improve the efficiency of the machine operation and better control the particle beam a new advanced design embedding Beam Position Monitors (BPM) into the movable collimator jaws has been developed. This paper describes the mechanical design of various types of future collimators with embedded BPMs. Experimental measurements performed on a simplified functional prototype installed in the CERN SPS showed that, thanks to on-board BPMs, the collimator could be precisely, rapidly, and safely aligned and the beam position accurately measured.

TUPS037	Preliminary Assessment of Beam Impact Consequences on LHC Collimators	1617
	M. Cauchi, R.W. Assmann, A. Bertarelli, R. Bruce, F. Carra, A. Dallocchio, D. Deboy, N. Mariani, A. Rossi, N.J. Sammut CERN, Geneva, Switzerland M. Cauchi, P. Mollicone UoM, Msida, Malta L. Lari IFIC, Valencia, Spain
	The correct functioning of the LHC collimation system is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, the robustness of the collimators plays an important role. An accident which causes the proton beam to hit a collimator might result in severe beam-induced damage and, in some cases, replacement of the collimator, with consequent downtime for the machine. In this paper, several case studies representing different realistic beam impact scenarios are shown. A preliminary analysis of the thermal response of tertiary collimators to beam impact is presented, from which the most critical cases can be identified. Such work will also help to give an initial insight on the operational constraints of the LHC by taking into account all relevant collimator damage limits.

TUPS038	Design of a Beam Dump for 3 to 100 MeV for the New H⁻ Beam in the CERN Linac4	1620
	C. Maglioni CERN, Geneva, Switzerland
	In this paper the design of a beam dump for the energy range from 3 to 100 MeV is reported. The dump is developed as temporary dump for the commissioning phase of the Linac4 Project, under construction at CERN, and will be installed in different periods to withstand a beam of different intensities and energies, following the chronological assembly of the linac. The dump design and its functionalities, as well as material choice, criticalities and cooling system are described. Finally, the results from the numerical and analytical thermo-mechanical analyses are reported, while the use of the dump also at 160 MeV is investigated.

TUPS039	Reduction of Magnetic Interference on the Position Sensors of the LHC Collimators	1623
	A. Masi, M. Lamberti, R. Losito, M. Martino CERN, Geneva, Switzerland
	The jaws of the LHC collimators have to be positioned with respect to the beam with an accuracy of 20 μm. On some collimators, installed in the LHC transfer lines from SPS, huge reading errors of several tens of micrometers have been observed on the Linear Variable Differential Transformer (LVDT) positioning sensors in synchronization with the variable magnetic field produced by the feed cables of the pulsed resistive dipoles of the transfer line. In this paper we introduce and describe in detail the problem, the model developed using FLUXTM for the simulation of the magnetic flux density generated by the current cables in the complex environment of an LHC transfer line, and the magnetic shielding we designed and implemented. Finally, we compare the results of simulations with experimental measurements taken during on-line pulsed magnets test campaigns.

TUPS040	Driving the LHC Collimators' Stepping Motors over 1 km with High Accuracy avoiding EMI Effects	1626
	A. Masi, G. Conte, R. Losito, M. Martino CERN, Geneva, Switzerland
	The LHC collimators are exposed to very high levels of radiation, which means that the power drivers must be installed far from the stepping motors that they drive. Due to the geometry of the underground installations, the distances can be up to 1 km. The long cables that connect the drivers to the motors behave as transmission lines modifying dramatically the impedance seen by the drivers and consequently jeopardizing the control performance of Pulse Width Modulation (PWM) drivers. In this paper we address this problem, provide an analytical model of the driver-cable-motor system and describe the analog solution we have developed to improve the performance of a typical off the shelf driver. Finally we characterize the improvement of the performances with measurements of positioning repeatability and show that electromagnetic emissions from the long cables are drastically reduced, making the use of stepping motors compatible with extremely sensitive instrumentation such as the LHC Beam Loss Monitors (BLM).

TUPS041	Thermo-mechanical Study of a CLIC Bunch Train hitting a Beryllium Energy Spoiler Model	1629
	J.-L. Fernández-Hernando, D. Angal-Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom J. Resta-López IFIC, Valencia, Spain
	A thermo-mechanical study of the impact a CLIC bunch train has over a beryllium energy spoiler has been made. Beryllium has a high electrical and thermal conductivity which together with a large radiation length compared to other metals makes it an optimal candidate for a long tapered design spoiler that will not generate high wakefields, which might degrade the orbit stability and affect the collider luminosity. This paper shows the progress made from the paper presented last year in IPAC 2010. While in the aforementioned paper the study of the temperature and stress was made for the duration of the bunch train this time the study shows the evolution of the stress in the spoiler body 3 microseconds after the bunch train hit.

TUPZ011	LHC Collimation with a Reduced Beam Pipe Radius in ATLAS	1822
	R. Bruce, R.W. Assmann CERN, Geneva, Switzerland
	Based on SixTrack simulations, we investigate the effect from collimation of a reduced beam pipe in the ATLAS experiment in the LHC. Several running scenarios are studied with range of different beam pipe radii and in each case we conclude on the minimum allowed aperture, which does not cause beam losses inside the detectors.

THOBB03	Research and Development of Novel Advanced Materials for Next-generation Collimators	2888
	A. Bertarelli, G. Arnau-Izquierdo, F. Carra, A. Dallocchio, M. Gil Costa, N. Mariani CERN, Geneva, Switzerland
	Funding: This work has partly been carried out through the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. The study of innovative collimators is essential to handle the high energy particle beams required to explore unknown territory in basic research. This calls for the development of novel advanced materials, as no existing metal-based or carbon-based material possesses the combination of physical, thermal, electrical and mechanical properties, imposed by collimator extreme working conditions. A new family of materials, with promising features, has been identified: metal-diamond composites. These materials are to combine the outstanding thermal and physical properties of diamond with the electrical and mechanical properties of metals. The best candidates are Copper-Diamond (Cu-CD) and Molybdenum-Diamond (Mo-CD). In particular, Mo-CD may provide interesting properties as to mechanical strength, melting temperature, thermal shock resistance and, thanks to its balanced material density, energy absorption. The research program carried out on these materials at CERN and collaborating partners is presented, mainly focusing on the theoretical investigation, material characterization, and manufacturing processes.
	Slides THOBB03 [3.948 MB]