IBIC2015 - List of Authors (Dehning, B.)

Paper	Title	Page
MOPB042	Beam Loss Monitors for the Cryogenic LHC Magnets	139
	M.R. Bartosik, A. Alexopoulos, B. Dehning, M. Sapinski CERN, Geneva, Switzerland V. Eremin, E. Verbitskaya IOFFE, St. Petersburg, Russia E. Griesmayer CIVIDEC Instrumentation, Wien, Austria
	Funding: This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485. The Beam Loss Monitoring system of the Large Hadron Collider close to the interaction points contains mostly gas ionization chambers working at room temperature, located far from the superconducting coils of the magnets. The system records particles lost from circulating proton beams, but is also sensitive to particles coming from the experimental collisions, which do not contribute significantly to the heat deposition in the superconducting coils. In the future, with beams of higher brightness resulting in higher luminosity, distinguishing between these interaction products and dangerous quench-provoking beam losses from the circulating beams will be difficult. It is proposed to optimise by locating beam loss monitors inside the cold mass of the magnets, housing the superconducting coils, in a superfluid helium environment, at 1.9 K. This contribution will present results of radiation hardness test of p⁺-n-n+ silicon detectors which, together with single crystal Chemical Vapour Deposition diamond, are the main candidates for these future cryogenic beam loss monitors.
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TUPB052	Wire Scanners and Vibrations - Models and Measurements	437
	J. Herranz, B. Dehning, E. Effinger, J. Emery, A. Guerrero, C. Pereira CERN, Geneva, Switzerland A. Barjau, J. Herranz Universitat Politécnica de Catalunya, Barcelona, Spain J. Herranz Proactive Research and Development, Barcelona, Spain
	The new fast wire scanner foreseen to measure small emittance beams throughout the LHC injector chain will have a wire travelling at a speed of up to 20 m.s⁻¹, with a requested wire position measurement accuracy of the order of a few microns. The vibration of the thin carbon wires used has been identified as one of the major error sources on the wire position accuracy. In this project the most challenging and innovative development has been the wire vibrations measurement strategy based on the piezo resistive effect of the wire itself, while the deflection of the fork supporting the wire has been measured by semiconductor strain gauges. Dynamic models of the wire and fork have been created to predict the behaviour of the fork-wire assembly. This model, validated by the measurements, has then been used for optimisation of the wire-fork assembly. The contribution will discuss the measurement setup and the model development as well as their comparison. In addition it will show that this technology can easily be implemented in current operating devices without major modifications. For the first time the piezo resistive effect is used for wire vibrations measurements during the scan.
	Poster TUPB052 [2.455 MB]
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TUPB053	A High Dynamic Range Diamond Detector Readout System for the CERN Beam Wire Scanners Program	441
	J.L. Sirvent Blasco, B. Dehning, J. Emery CERN, Geneva, Switzerland A. Dieguez UB, Barcelona, Spain
	A secondary particle shower acquisition system is under design for the upgrade of CERN's beam wire scanners. The system needs to be capable of performing bunch-by-bunch synchronous measurements with an integration time of 25 ns and to cope with signal variations of up to 6 orders of magnitude. The whole dynamic range should be covered by the acquisition system with a single configuration and should have no tuneable parameters. The secondary particles are detected using a polycrystalline diamond detector with the signal digitization performed nearby with a custom front-end system, designed to resist a total ionising radiation dose up to 1 kGy in 10 years. The digital data transmission, front-end synchronization and control are performed through a bi-directional optical link operating at 4.8 Gbps using CERN's GBT protocol. For the digitization, two radiation tolerant integrator ASICs (ICECAL and QIE10) are under study.
	Poster TUPB053 [1.323 MB]
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TUPB059	Development of an Ionization Profile Monitor Based on a Pixel Detector for the CERN Proton Synchrotron	470
	J.W. Storey, D. Bodart, B. Dehning, S. Levasseur, P. Pacholek, A. Rakai, M. Sapinski, G. Schneider, D. Steyart CERN, Geneva, Switzerland K. Satou JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The transverse emittance measurement in the CERN Proton Synchrotron is currently performed using fast rotational wire scanners. These scanners cannot provide continuous bunch-by-bunch measurements and the expected future increase of the beam brightness will lead to an accelerated sublimation of the wire. A novel Ionization Profile Monitor is being constructed to cope with these challenges. The readout of this device will be based on a hybrid silicon pixel detector with a Timepix3 chip. Pixel detectors are sensitive to single electrons therefore eliminating the need for traditional Multi-Channel Plates, which suffer from ageing phenomena. The early digitization of the signal will reduce the susceptibility of the readout system to electromagnetic interference, while the time resolution of the chip allows the required bunch-by-bunch measurement. Due to the small length of the detector a new, simplified ion trap has been designed. Resistive glass plates are used to provide maximum uniformity of the electric field and to simplify construction. The guiding field will be provided by a new, self-compensating magnet. It is foreseen to have the device ready for testing with beam in 2016.
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TUPB061	Experience From the Construction of a New Fast Wire Scanner Prototype for the CERN- SPS and its Optimisation for Installation in the CERN-PS Booster	479
	R. Veness, W. Andreazza, N. Chritin, B. Dehning, J. Emery, D. Gudkov, J. Herranz, P. Magagnin, E. Piselli, S. Samuelsson CERN, Geneva, Switzerland
	A new design of wire scanner is under development for the LHC Injector Upgrade project at CERN. A prototype has been designed, built and installed in the SPS accelerator to test the concept in an operational accelerator environment. New technology has been developed and qualified for in-vacuum motor and structural components using 3D metal additive machining. This paper will describe the technology developed for this scanner and the test results to date. This prototype has recently been re-optimised to fit in the limited space available in the PS Booster rings. This design will also be presented.
	Poster TUPB061 [0.887 MB]
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WEALA02	First LHC Emittance Measurements at 6.5 TeV	562
	M. Kuhn, F. Antoniou, E. Bravin, B. Dehning, J. Emery, V. Kain, A. Langner, Y. Papaphilippou, E. Piselli, G. Trad CERN, Geneva, Switzerland
	During LHC Run 1 significant transverse emittance growth through the LHC cycle was observed. Measurements indicated most of the blow-up to occur during the injection plateau and the ramp. Intra beam scattering was one of the main drivers of emittance growth. However, finding a good wire scanner working point was difficult. Photomultiplier saturation added uncertainty on all measurements. A large discrepancy between emittances from wire scanners and luminosity was discovered but not solved. During Long Shutdown 1 the wire scanner system was upgraded with new photomultipliers. In April 2015 the LHC re-started with collision energy of 6.5 TeV per beam. This paper presents the first transverse emittance measurements through the LHC Run 2 cycle with low beam intensity. Comparisons with data from the synchrotron light monitors and the LHC experiments will be discussed and results summarized. In addition, a thorough study of wire scanner photomultiplier saturation will be presented. Finally, the emittance growth results will be compared to intra beam scattering simulations.
	Slides WEALA02 [6.752 MB]
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Paper

Title

Page

Beam Loss Monitors for the Cryogenic LHC Magnets

139

M.R. Bartosik, A. Alexopoulos, B. Dehning, M. Sapinski
CERN, Geneva, Switzerland
V. Eremin, E. Verbitskaya
IOFFE, St. Petersburg, Russia
E. Griesmayer
CIVIDEC Instrumentation, Wien, Austria

Funding: This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485.
The Beam Loss Monitoring system of the Large Hadron Collider close to the interaction points contains mostly gas ionization chambers working at room temperature, located far from the superconducting coils of the magnets. The system records particles lost from circulating proton beams, but is also sensitive to particles coming from the experimental collisions, which do not contribute significantly to the heat deposition in the superconducting coils. In the future, with beams of higher brightness resulting in higher luminosity, distinguishing between these interaction products and dangerous quench-provoking beam losses from the circulating beams will be difficult. It is proposed to optimise by locating beam loss monitors inside the cold mass of the magnets, housing the superconducting coils, in a superfluid helium environment, at 1.9 K. This contribution will present results of radiation hardness test of p⁺-n-n+ silicon detectors which, together with single crystal Chemical Vapour Deposition diamond, are the main candidates for these future cryogenic beam loss monitors.

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TUPB052

Wire Scanners and Vibrations - Models and Measurements

437

J. Herranz, B. Dehning, E. Effinger, J. Emery, A. Guerrero, C. Pereira
CERN, Geneva, Switzerland
A. Barjau, J. Herranz
Universitat Politécnica de Catalunya, Barcelona, Spain
J. Herranz
Proactive Research and Development, Barcelona, Spain

The new fast wire scanner foreseen to measure small emittance beams throughout the LHC injector chain will have a wire travelling at a speed of up to 20 m.s⁻¹, with a requested wire position measurement accuracy of the order of a few microns. The vibration of the thin carbon wires used has been identified as one of the major error sources on the wire position accuracy. In this project the most challenging and innovative development has been the wire vibrations measurement strategy based on the piezo resistive effect of the wire itself, while the deflection of the fork supporting the wire has been measured by semiconductor strain gauges. Dynamic models of the wire and fork have been created to predict the behaviour of the fork-wire assembly. This model, validated by the measurements, has then been used for optimisation of the wire-fork assembly. The contribution will discuss the measurement setup and the model development as well as their comparison. In addition it will show that this technology can easily be implemented in current operating devices without major modifications. For the first time the piezo resistive effect is used for wire vibrations measurements during the scan.

Poster TUPB052 [2.455 MB]

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TUPB053

A High Dynamic Range Diamond Detector Readout System for the CERN Beam Wire Scanners Program

441

J.L. Sirvent Blasco, B. Dehning, J. Emery
CERN, Geneva, Switzerland
A. Dieguez
UB, Barcelona, Spain

A secondary particle shower acquisition system is under design for the upgrade of CERN's beam wire scanners. The system needs to be capable of performing bunch-by-bunch synchronous measurements with an integration time of 25 ns and to cope with signal variations of up to 6 orders of magnitude. The whole dynamic range should be covered by the acquisition system with a single configuration and should have no tuneable parameters. The secondary particles are detected using a polycrystalline diamond detector with the signal digitization performed nearby with a custom front-end system, designed to resist a total ionising radiation dose up to 1 kGy in 10 years. The digital data transmission, front-end synchronization and control are performed through a bi-directional optical link operating at 4.8 Gbps using CERN's GBT protocol. For the digitization, two radiation tolerant integrator ASICs (ICECAL and QIE10) are under study.

Poster TUPB053 [1.323 MB]

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TUPB059

Development of an Ionization Profile Monitor Based on a Pixel Detector for the CERN Proton Synchrotron

470

J.W. Storey, D. Bodart, B. Dehning, S. Levasseur, P. Pacholek, A. Rakai, M. Sapinski, G. Schneider, D. Steyart
CERN, Geneva, Switzerland
K. Satou
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The transverse emittance measurement in the CERN Proton Synchrotron is currently performed using fast rotational wire scanners. These scanners cannot provide continuous bunch-by-bunch measurements and the expected future increase of the beam brightness will lead to an accelerated sublimation of the wire. A novel Ionization Profile Monitor is being constructed to cope with these challenges. The readout of this device will be based on a hybrid silicon pixel detector with a Timepix3 chip. Pixel detectors are sensitive to single electrons therefore eliminating the need for traditional Multi-Channel Plates, which suffer from ageing phenomena. The early digitization of the signal will reduce the susceptibility of the readout system to electromagnetic interference, while the time resolution of the chip allows the required bunch-by-bunch measurement. Due to the small length of the detector a new, simplified ion trap has been designed. Resistive glass plates are used to provide maximum uniformity of the electric field and to simplify construction. The guiding field will be provided by a new, self-compensating magnet. It is foreseen to have the device ready for testing with beam in 2016.

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TUPB061

Experience From the Construction of a New Fast Wire Scanner Prototype for the CERN- SPS and its Optimisation for Installation in the CERN-PS Booster

479

R. Veness, W. Andreazza, N. Chritin, B. Dehning, J. Emery, D. Gudkov, J. Herranz, P. Magagnin, E. Piselli, S. Samuelsson
CERN, Geneva, Switzerland

A new design of wire scanner is under development for the LHC Injector Upgrade project at CERN. A prototype has been designed, built and installed in the SPS accelerator to test the concept in an operational accelerator environment. New technology has been developed and qualified for in-vacuum motor and structural components using 3D metal additive machining. This paper will describe the technology developed for this scanner and the test results to date. This prototype has recently been re-optimised to fit in the limited space available in the PS Booster rings. This design will also be presented.

Poster TUPB061 [0.887 MB]

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WEALA02

First LHC Emittance Measurements at 6.5 TeV

562

M. Kuhn, F. Antoniou, E. Bravin, B. Dehning, J. Emery, V. Kain, A. Langner, Y. Papaphilippou, E. Piselli, G. Trad
CERN, Geneva, Switzerland

During LHC Run 1 significant transverse emittance growth through the LHC cycle was observed. Measurements indicated most of the blow-up to occur during the injection plateau and the ramp. Intra beam scattering was one of the main drivers of emittance growth. However, finding a good wire scanner working point was difficult. Photomultiplier saturation added uncertainty on all measurements. A large discrepancy between emittances from wire scanners and luminosity was discovered but not solved. During Long Shutdown 1 the wire scanner system was upgraded with new photomultipliers. In April 2015 the LHC re-started with collision energy of 6.5 TeV per beam. This paper presents the first transverse emittance measurements through the LHC Run 2 cycle with low beam intensity. Comparisons with data from the synchrotron light monitors and the LHC experiments will be discussed and results summarized. In addition, a thorough study of wire scanner photomultiplier saturation will be presented. Finally, the emittance growth results will be compared to intra beam scattering simulations.

Slides WEALA02 [6.752 MB]

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