IBIC2013 - List of Keywords (LHC)

Paper	Title	Other Keywords	Page
MOCL2	Design of a Novel Cherenkov Detector System for Machine Induced Background Monitoring in the CMS Cavern	background, simulation, radiation, shielding	33
	S. Orfanelli, A.E. Dabrowski, M. Giunta CERN, Geneva, Switzerland M.J. Ambrose, A. Finkel, R. Rusack University of Minnesota, Minneapolis, Minnesota, USA D.P. Stickland PU, Princeton, New Jersey, USA
	A novel detector system has been designed for an efficient online measurement of the machine induced background in the CMS experimental cavern. The suppression of the CMS cavern background originating from pp collision products and the 25 ns bunch spacing have set the requirements for the detector design. Each detector unit will be a radiation hard, cylindrical Cherenkov radiator optically coupled to an ultra-fast UV-sensitive photomultiplier tube, providing a prompt, directionally sensitive measurement. Simulation and test beam measurements have shown the achievability of the goals that have driven the baseline design. The system will consist of 20 azimuthally distributed detectors per end, installed at a radius of r ~ 180 cm and a distance 20.6 m away from the CMS interaction region. The detector units will enable a measurement of the transverse distribution of the bunch-by-bunch machine induced background flux. This will provide important feedback from the CMS on the beam conditions during the LHC machine setup and comparisons to expectations based on FLUKA simulations.
	Slides MOCL2 [14.094 MB]

MOPC17	Calibration of a Non-Linear Beam Position Monitor Electronics by Switching Electrode Signals	BPM, beam-position, SPS, CERN	85
	M. Gasior CERN, Geneva, Switzerland
	Button electrode signals from beam position monitors embedded into new LHC collimators will be individually processed with front-end electronics based on compensated diode detectors and digitized with 24-bit audio-range ADCs. This scheme allows sub-micrometre beam orbit resolution to be achieved with simple hardware and no external timing. As the diode detectors only operate in a linear regime with large amplitude signals, offset errors of the electronics cannot be calibrated in the classical way with no input. This paper describes the algorithms developed to calibrate the offset and gain asymmetry of these nonlinear electronic channels. Presented algorithm application examples are based on measurements performed with prototype diode orbit systems installed on the CERN SPS and LHC machines.

MOPC35	A Beam-Synchronous Gated Peak-Detector for the LHC Beam Observation System	CERN, longitudinal, injection, synchrotron	147
	T.E. Levens, T. Bohl, U. Wehrle CERN, Geneva, Switzerland
	Measurements of the bunch peak amplitude using the longitudinal wideband wall-current monitor are a vital tool used in the Large Hadron Collider (LHC) beam observation system. These peak-detected measurements can be used to diagnose bunch shape oscillations, for example coherent quadrupole oscillations, that occur at injection and during beam manipulations. Peak-detected Schottky diagnostics can also be used to obtain the synchrotron frequency distribution and other parameters from a bunched beam under stable conditions. For the LHC a beam-synchronous gated peak detector has been developed to allow individual bunches to be monitored without the influence of other bunches circulating in the machine. The requirement for the observation of both low intensity pilot bunches and high intensity bunches for physics requires a detector front-end with a high bandwidth and a large dynamic range while the usage for Schottky measurements requires low noise electronics. This paper will present the design of this detector system as well as initial results obtained during the 2012-2013 LHC run.
	Poster MOPC35 [2.792 MB]

MOPC43	Performance of Detectors using Diamond Sensors at the LHC and CMS	DIAMOND, beam-losses, luminosity, injection	174
	M. Hempel BTU, Cottbus, Germany T. Baer, A.E. Dabrowski CERN, Geneva, Switzerland E. Griesmayer ATI, Wien, Austria W. Lange, O. Novgorodova DESY Zeuthen, Zeuthen, Germany W. Lohmann DESY, Hamburg, Germany N.J. Odell NU, Evanston, USA D.P. Stickland PU, Princeton, New Jersey, USA
	Diamond detectors are used as beam loss and luminosity monitors for CMS and LHC. A time resolution in the nanosecond range allows to detect beam losses and luminosities of single bunches. The radiation hardness and negligible temperature dependence allow the usage of diamond sensors in high radiation fields without cooling. Two different diamond detector types are installed at LHC and CMS. One is based on pCVD diamonds and installed at different locations in the LHC tunnel for beam loss monitoring. Measurements of these detectors are used to perform a bunch-by-bunch beam loss analysis. They allow to disentangle the origin of beam losses. The second type uses sCVD diamonds and is located inside CMS for van-der-Meer scan, beam halo and online luminosity monitoring and around the LHC tunnel for beam loss observation. Results on the performance of these detectors will be presented and examples of the use for analyzing the beam conditions will be given. In order to persist the enhanced requirements of the LHC after the long shutdown, e.g. higher luminosity, an upgrade of the detectors is required. The concept of the new detectors will be presented and first results will be shown.
	Poster MOPC43 [0.721 MB]

MOPC44	A Gigabit Ethernet Link for an FPGA Based Beam Loss Measurement System	CERN, beam-losses, monitoring, instrumentation	178
	M. Kwiatkowski, M. Alsdorf, B. Dehning, W. Viganò, C. Zamantzas CERN, Geneva, Switzerland
	A new Beam Loss Measurement (BLM) system is under development at the European Organisation for Nuclear Research (CERN) within the LHC Injector Upgrade (LIU) project. The multi-channel system will measure the beam losses from various types of detectors with a high precision and wide dynamic range. Several modes of data acquisition are supported. The data rate in the single-channel mode is 16 Mbps and in the multi-channel mode 128 Mbps. The Gigabit Ethernet link is implemented in an FPGA, which allows both a high throughput and a quick validation of the digital data processing algorithms using standard PCs in the initial stages of the development. Both TCP and UDP protocols were explored. The implementation of the Ethernet link is flexible and proved to be highly reliable, leading to its planned use in other measurement systems developed at CERN. The implementation details of the Ethernet link and the results achieved will be described in this paper.
	Poster MOPC44 [0.833 MB]

MOPC45	A Prototype Readout System for the Diamond Beam Loss Monitors at LHC	beam-losses, DIAMOND, injection, proton	182
	E. Effinger, T. Baer, B. Dehning, R. Schmidt CERN, Geneva, Switzerland H. Frais-Kölbl FH WN, Wiener Neustadt, Austria E. Griesmayer ATI, Wien, Austria P. Kavrigin CIVIDEC Instrumentation, Wien, Austria
	Diamond Beam Loss Monitors are used at the LHC for the measurement of fast beam losses. Results from specimen LHC loss measurements are presented in this talk. The bunch-to-bunch loss measurements make full use of the fast signal response of the diamond detectors with 1 ns time resolution and 6.7 ns double pulse resolution. The data processing is done with a dedicated readout system, which was designed and optimized for particular applications with the diamond beam loss monitors. This FPGA-based system provides on-line, real-time, and dead-time-free data processing. Several examples are presented: the Time Loss Histogram with 1.6 ns binning provides beam loss measurements that are synchronized with the revolution period throughout the full operational LHC cycle. The Post Mortem Recorder with a sampling frequency of 1 GS/s allows beam-loss-based tune estimates for all bunches in parallel. Future applications and upgrades are discussed.
	Poster MOPC45 [0.778 MB]

MOPF07	Turn by Turn Profile Monitors for the CERN SPS and LHC	OTR, SPS, optics, proton	216
	S. Burger, A. Boccardi, E. Bravin, A. Goldblatt, A. Ravni, F. Roncarolo, R.S. Sautier CERN, Geneva, Switzerland
	In order to preserve the transverse beam emittance along the acceleration chain it is important that the optics of the transfer lines is perfectly matched to the optics of the rings. Special monitors capable of measuring the beam profiles with a turn by turn resolution are very helpful in this respect. A new type of matching monitor has been developed at CERN for the SPS and LHC machines. This monitor relies on imaging OTR light by mean of a fast line scan CMOS and an asymmetric optical system based on cylindrical lenses. This contribution describes the design of this monitor, presents the results obtained during the 2012-13 run and outlines the plans for further improving the design.

MOPF08	Design and Performance of the Upgraded LHC Synchrotron Light Monitor	focusing, undulator, optics, dipole	220
	A. Goldblatt, E. Bravin, F. Roncarolo, G. Trad CERN, Geneva, Switzerland
	The LHC is equipped with two synchrotron radiation systems, one per beam, used to measure the transverse bunch distributions. The light emitted by a superconducting undulator and/or by a dipole magnet (depending on beam energy) is intercepted by an extraction mirror in vacuum and sent through a viewport to the imaging Beam Synchrotron Radiation Telescope (BSRT). The first version of the telescope, used from 2009 to mid 2012, was based on spherical focusing mirrors in order to minimize chromatic aberrations. However, this required a very complicated delay line in order to switch the focus between the two different light sources as a function of beam energy. A new system based on optical lenses was designed and installed in mid 2012 in order to simplify the optical line and thus reduce misalignment and focusing errors. The first results with LHC beam using this new system showed a significant reduction in the correction factor required to match the emittance as measured by wire scanners. This contribution discusses the performance of the new optical system, presenting the LHC results and comparing simulations with measurement performed in the laboratory using a BSRT replica.

MOPF29	A Non-Invasive Beam Monitor for Hadron Therapy Beams	proton, CERN, target, vacuum	283
	T. Cybulski, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom T. Cybulski, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom A. Kacperek, B. Marsland, I. Taylor, A. Wray The Douglas Cyclotron, The Clatterbridge Cancer Centre NHS Foundation Trust, Wirral, United Kingdom
	Funding: Work supported by the EU under contract PITN-GA-2008-215080 and the STFC Cockcroft Institute Core Grant No. ST/G008248/1 Hadron therapy allows for precise dose delivery to the tumour volume only and hence decreases the dose delivered to the nearby organs and healthy tissue. Ideally, the beam would be monitored whilst being delivered to the patient. A novel, real–time and non-interceptive beam monitor for hadron therapy beams has been developed in the QUASAR Group. It is based on the LHCb VErtex LOcator (VELO) detector and couples to the treatment beam’s transverse halo to determine the intensity, position and ultimately the dose of the treatment beam. This contribution presents the design of a stand-alone version of the VELO detector which was developed for the Clatterbridge Cancer Centre (CCC) treatment line. The mechanical and electronic design of the monitor and its data acquisition system are shown, with a focus on the detector positioning and cooling system. Monte Carlo simulations into expected signal distributions are compared against first measurements with the 60 MeV proton beam at CCC.

TUBL3	A Multiband-Instability-Monitor for High-Frequency Intra-Bunch Beam Diagnostics	CERN, SPS, synchrotron, pick-up	327
	R.J. Steinhagen CERN, Geneva, Switzerland M.J. Boland, T.G. Lucas The University of Melbourne, Melbourne, Australia
	To provide the best possible luminosity, even higher beam intensities are needed in the Large Hadron Collider (LHC) and in its injector chain. This is fundamentally limited by self-amplifying beam instabilities, intrinsic to unavoidable imperfections in accelerators. Traditionally, intra-bunch or head-tail particle motion is measured using fast digitizers, which even using state-of-the-art technology are limited in their effective intra-bunch position resolution to few tens of um in the multi-GHz regime. Oscillations at this scale cause partial or total loss of the beam due to the tight transverse constraints imposed by the LHC collimation system. To improve on the present signal processing, a prototype system has been designed, constructed and tested at the CERN Super-Proton-Synchrotron (SPS) and later on LHC. The system splits the signal into multiple equally-spaced narrow frequency bands that are processed and analysed in parallel. Working with narrow-band signals in frequency-domain permits the use of much higher resolution analogue-to-digital-converters that can be used to resolve nm-scale particle motion already during the onset of instabilities.
	Slides TUBL3 [3.165 MB]

TUPF03	Performance Assessment of Wire-Scanners at CERN	SPS, CERN, laser, synchrotron	499
	G. Baud, B. Dehning, J. Emery, J-J. Gras, A. Guerrero, E.P. Piselli CERN, Geneva, Switzerland
	This article describes the current fast wire-scanner devices installed in circular accelerators at CERN with an emphasis of the error studies carried out during the last two runs. At present the wire-scanners have similar acquisition systems but are varied in terms of mechanics. Several measurement campaigns were performed aimed at establishing optimal operational settings and to identify and assess systematic errors. In several cases the results led to direct performance improvements while in others this helped in defining the requirements for new detectors.
	Poster TUPF03 [1.040 MB]

TUPF29	Tune Measurement from Transverse Feedback Signals in LHC	feedback, transverse, damping, CERN	579
	F. Dubouchet, W. Höfle, G. Kotzian, T.E. Levens, D. Valuch CERN, Geneva, Switzerland P. Albuquerque HES-SO//Geneva, Geneva, Switzerland
	We show how bunch-by-bunch position data from the LHC transverse feedback system can be used to determine the transverse tunes. Results from machine development experiments are presented and compared with theoretical predictions. In the absence of external beam excitations the tune is visible in the spectra of the position data with the feedback loop as a dip, while with external excitation a peak is visible. Both options, observation with and without excitation, are demonstrated to be complementary. Periodic excitation and observation of the free oscillation can also be used to determine the damping time of the feedback in addition to the coherent tune. Plans are outlined for hardware upgrades of the LHC transverse feedback system that will enable fast online processing of bunch-by-bunch, turn-by-turn data using Graphical Processing Units (GPU). By using GPUs we gain the ability to compute and store the spectrum of all bunches in real-time and the possibility to reconfigure test and deploy algorithms. This data acquisition and analysis architecture also allows changes to be made without disturbing the operation.
	Poster TUPF29 [1.052 MB]

WEPC44	Operation of Silicon, Diamond and Liquid Helium Detectors in the Range of Room Temperature to 1.9 Kelvin and After an Irradiation Dose of Several Mega Gray	DIAMOND, proton, beam-losses, CERN	791
	C. Kurfuerst, M.R. Bartosik, B. Dehning, T. Eisel, M. Sapinski CERN, Geneva, Switzerland V. Eremin IOFFE, St. Petersburg, Russia
	At the triplet magnets close to the interaction regions of the LHC, the current Beam Loss Monitoring system is sensitive to the debris from the collision points. For future beams with higher energy and intensity, the expected increase in luminosity and associated increase of the debris from interaction products is expected to compete with any quench-provoking beam losses from the primary proton beams. In order to distinguish between the two, it is proposed to locate the detectors as close as possible to the superconducting coil. The detectors therefore have to be located inside the cold mass of the superconducting magnets in superfluid helium at 1.9 K. Past measurements have shown that in a liquid helium chamber, diamond and silicon detectors are promising candidates for cryogenic beam loss monitors. This contribution will show the results from new high irradiation beam measurements at both room temperature and 1.9 Kelvin to reveal the radiation tolerance of these different detectors.

WEPC45	Beam Loss Monitoring at the European Spallation Source	beam-losses, ESS, XFEL, simulation	795
	L. Tchelidze, H. Hassanzadegan, A. Jansson, M. Jarosz ESS, Lund, Sweden
	At the European Spallation Source proton linear accelerator will generate 5 MW protons to be delivered to a target. This high power accelerator will require significant amount of beam instrumentation, among which the beam loss monitoring system is one of the most important for operation. An LHC type ionization chamber will be used with ~54 uC/Gy sensitivity. At most 1.5 mGy/sec radiation levels are expected close to the beam pipe during normal operation, resulting in up to 80 nA current signal in detectors. Loss monitor electronics is designed to be able to measure currents as little as 1% of the expected current up to as much as 1% of the total beam loss, thus ~800 pA – few mA. In order to study beam loss pattern along the accelerator a coherent model of the whole machine is created for the purposes of Monte Carlo particle transport simulations. Data obtained using the model will be stored in a database together with the initial beam loss conditions. The contents of the database will then be processed using custom neural network algorithms to optimize number and position of the loss monitors and to provide reference on the beam loss localization during operation of the machine.
	Poster WEPC45 [1.784 MB]

WEPC46	Beam Delivery Simulation (BDSIM): A Geant4 Based Toolkit for Diagnostics and Loss Simulation	CLIC, simulation, lattice, background	799
	S.T. Boogert Royal Holloway, University of London, Surrey, United Kingdom S.T. Boogert, S.M. Gibson, R. Kwee-Hinzmann, L.J. Nevay, J. Snuverink JAI, Egham, Surrey, United Kingdom L.C. Deacon CERN, Geneva, Switzerland
	BDSIM is a Geant4 and C++ based particle tracking code which seamlessly tracks particles in accelerators and particle detectors, including the full range of particle interaction physics processes in Geant4. The code has been used to model the backgrounds in the International Linear Collider (ILC), Compact Linear Collider (CLIC), Accelerator Test Facility 2 (ATF2) and more recently the Large Hadron Collider (LHC). This paper outlines the current code and possible example applications and presents a roadmap for future developments.

WEPF29	The LHC Fast Beam Current Change Monitor	injection, CERN, FIR, beam-losses	887
	D. Belohrad, J.M. Belleman, L.K. Jensen, M. Krupa, A. Topaloudis CERN, Geneva, Switzerland
	The modularity of the Large Hadron Collider’s (LHC) machine protection system (MPS) allows for the integration of several beam diagnostic instruments. These instruments have not necessarily been designed to have protection functionality, but MPS can still use them to increase the redundancy and reliability of the machine. The LHC fast beam current change monitor (FBCCM) is an example. It is based on analogue signals from fast beam current transformers (FBCT) used nominally to measure the LHC bunch intensities. The FBCCM calculates the magnitude of the beam signal provided by the FBCT, looks for a change over specific time intervals, and triggers a beam dump interlock if losses exceed an energy-dependent threshold. The first prototype of the FBCCM was installed in the LHC during the 2012-2013 run. The aim of this article is to present the FBCCM system and the results obtained, analyse its current performance and provide an outlook for the final system which is expected to be operational after the long LHC shutdown.

THBL1	RF Heating from Wake Losses in Diagnostics Structures	resonance, longitudinal, impedance, simulation	929
	E. Métral CERN, Geneva, Switzerland
	Heating of diagnostics structures (striplines, buttons, screen vessels, wire scanners etc) has been observed at many facilities with higher stored currents. Simulations of wake losses using 3D EM codes are regularly used to estimate the amount of power lost from the bunched beam but on its own this does not tell how much is radiated back into the beam pipe or transmitted into external ports and how much is actually being dissipated in the structure and where. This talk should introduce into the matter, summarise some of the observations at various facilities and illustrate what approaches of detailed simulations have been taken. summarizing a workshop at DLS (see http://tinyurl.com/wakeloss )
	Slides THBL1 [9.078 MB]

Paper

Title

Other Keywords

Page

MOCL2

Design of a Novel Cherenkov Detector System for Machine Induced Background Monitoring in the CMS Cavern

background, simulation, radiation, shielding

33

S. Orfanelli, A.E. Dabrowski, M. Giunta
CERN, Geneva, Switzerland
M.J. Ambrose, A. Finkel, R. Rusack
University of Minnesota, Minneapolis, Minnesota, USA
D.P. Stickland
PU, Princeton, New Jersey, USA

A novel detector system has been designed for an efficient online measurement of the machine induced background in the CMS experimental cavern. The suppression of the CMS cavern background originating from pp collision products and the 25 ns bunch spacing have set the requirements for the detector design. Each detector unit will be a radiation hard, cylindrical Cherenkov radiator optically coupled to an ultra-fast UV-sensitive photomultiplier tube, providing a prompt, directionally sensitive measurement. Simulation and test beam measurements have shown the achievability of the goals that have driven the baseline design. The system will consist of 20 azimuthally distributed detectors per end, installed at a radius of r ~ 180 cm and a distance 20.6 m away from the CMS interaction region. The detector units will enable a measurement of the transverse distribution of the bunch-by-bunch machine induced background flux. This will provide important feedback from the CMS on the beam conditions during the LHC machine setup and comparisons to expectations based on FLUKA simulations.

Slides MOCL2 [14.094 MB]

MOPC17

Calibration of a Non-Linear Beam Position Monitor Electronics by Switching Electrode Signals

BPM, beam-position, SPS, CERN

85

M. Gasior
CERN, Geneva, Switzerland

Button electrode signals from beam position monitors embedded into new LHC collimators will be individually processed with front-end electronics based on compensated diode detectors and digitized with 24-bit audio-range ADCs. This scheme allows sub-micrometre beam orbit resolution to be achieved with simple hardware and no external timing. As the diode detectors only operate in a linear regime with large amplitude signals, offset errors of the electronics cannot be calibrated in the classical way with no input. This paper describes the algorithms developed to calibrate the offset and gain asymmetry of these nonlinear electronic channels. Presented algorithm application examples are based on measurements performed with prototype diode orbit systems installed on the CERN SPS and LHC machines.

MOPC35

A Beam-Synchronous Gated Peak-Detector for the LHC Beam Observation System

CERN, longitudinal, injection, synchrotron

147

T.E. Levens, T. Bohl, U. Wehrle
CERN, Geneva, Switzerland

Measurements of the bunch peak amplitude using the longitudinal wideband wall-current monitor are a vital tool used in the Large Hadron Collider (LHC) beam observation system. These peak-detected measurements can be used to diagnose bunch shape oscillations, for example coherent quadrupole oscillations, that occur at injection and during beam manipulations. Peak-detected Schottky diagnostics can also be used to obtain the synchrotron frequency distribution and other parameters from a bunched beam under stable conditions. For the LHC a beam-synchronous gated peak detector has been developed to allow individual bunches to be monitored without the influence of other bunches circulating in the machine. The requirement for the observation of both low intensity pilot bunches and high intensity bunches for physics requires a detector front-end with a high bandwidth and a large dynamic range while the usage for Schottky measurements requires low noise electronics. This paper will present the design of this detector system as well as initial results obtained during the 2012-2013 LHC run.

Poster MOPC35 [2.792 MB]

MOPC43

Performance of Detectors using Diamond Sensors at the LHC and CMS

DIAMOND, beam-losses, luminosity, injection

174

M. Hempel
BTU, Cottbus, Germany
T. Baer, A.E. Dabrowski
CERN, Geneva, Switzerland
E. Griesmayer
ATI, Wien, Austria
W. Lange, O. Novgorodova
DESY Zeuthen, Zeuthen, Germany
W. Lohmann
DESY, Hamburg, Germany
N.J. Odell
NU, Evanston, USA
D.P. Stickland
PU, Princeton, New Jersey, USA

Diamond detectors are used as beam loss and luminosity monitors for CMS and LHC. A time resolution in the nanosecond range allows to detect beam losses and luminosities of single bunches. The radiation hardness and negligible temperature dependence allow the usage of diamond sensors in high radiation fields without cooling. Two different diamond detector types are installed at LHC and CMS. One is based on pCVD diamonds and installed at different locations in the LHC tunnel for beam loss monitoring. Measurements of these detectors are used to perform a bunch-by-bunch beam loss analysis. They allow to disentangle the origin of beam losses. The second type uses sCVD diamonds and is located inside CMS for van-der-Meer scan, beam halo and online luminosity monitoring and around the LHC tunnel for beam loss observation. Results on the performance of these detectors will be presented and examples of the use for analyzing the beam conditions will be given. In order to persist the enhanced requirements of the LHC after the long shutdown, e.g. higher luminosity, an upgrade of the detectors is required. The concept of the new detectors will be presented and first results will be shown.

Poster MOPC43 [0.721 MB]

MOPC44

A Gigabit Ethernet Link for an FPGA Based Beam Loss Measurement System

CERN, beam-losses, monitoring, instrumentation

178

M. Kwiatkowski, M. Alsdorf, B. Dehning, W. Viganò, C. Zamantzas
CERN, Geneva, Switzerland

A new Beam Loss Measurement (BLM) system is under development at the European Organisation for Nuclear Research (CERN) within the LHC Injector Upgrade (LIU) project. The multi-channel system will measure the beam losses from various types of detectors with a high precision and wide dynamic range. Several modes of data acquisition are supported. The data rate in the single-channel mode is 16 Mbps and in the multi-channel mode 128 Mbps. The Gigabit Ethernet link is implemented in an FPGA, which allows both a high throughput and a quick validation of the digital data processing algorithms using standard PCs in the initial stages of the development. Both TCP and UDP protocols were explored. The implementation of the Ethernet link is flexible and proved to be highly reliable, leading to its planned use in other measurement systems developed at CERN. The implementation details of the Ethernet link and the results achieved will be described in this paper.

Poster MOPC44 [0.833 MB]

MOPC45

A Prototype Readout System for the Diamond Beam Loss Monitors at LHC

beam-losses, DIAMOND, injection, proton

182

E. Effinger, T. Baer, B. Dehning, R. Schmidt
CERN, Geneva, Switzerland
H. Frais-Kölbl
FH WN, Wiener Neustadt, Austria
E. Griesmayer
ATI, Wien, Austria
P. Kavrigin
CIVIDEC Instrumentation, Wien, Austria

Diamond Beam Loss Monitors are used at the LHC for the measurement of fast beam losses. Results from specimen LHC loss measurements are presented in this talk. The bunch-to-bunch loss measurements make full use of the fast signal response of the diamond detectors with 1 ns time resolution and 6.7 ns double pulse resolution. The data processing is done with a dedicated readout system, which was designed and optimized for particular applications with the diamond beam loss monitors. This FPGA-based system provides on-line, real-time, and dead-time-free data processing. Several examples are presented: the Time Loss Histogram with 1.6 ns binning provides beam loss measurements that are synchronized with the revolution period throughout the full operational LHC cycle. The Post Mortem Recorder with a sampling frequency of 1 GS/s allows beam-loss-based tune estimates for all bunches in parallel. Future applications and upgrades are discussed.

Poster MOPC45 [0.778 MB]

MOPF07

Turn by Turn Profile Monitors for the CERN SPS and LHC

OTR, SPS, optics, proton

216

S. Burger, A. Boccardi, E. Bravin, A. Goldblatt, A. Ravni, F. Roncarolo, R.S. Sautier
CERN, Geneva, Switzerland

In order to preserve the transverse beam emittance along the acceleration chain it is important that the optics of the transfer lines is perfectly matched to the optics of the rings. Special monitors capable of measuring the beam profiles with a turn by turn resolution are very helpful in this respect. A new type of matching monitor has been developed at CERN for the SPS and LHC machines. This monitor relies on imaging OTR light by mean of a fast line scan CMOS and an asymmetric optical system based on cylindrical lenses. This contribution describes the design of this monitor, presents the results obtained during the 2012-13 run and outlines the plans for further improving the design.

MOPF08

Design and Performance of the Upgraded LHC Synchrotron Light Monitor

focusing, undulator, optics, dipole

220

A. Goldblatt, E. Bravin, F. Roncarolo, G. Trad
CERN, Geneva, Switzerland

The LHC is equipped with two synchrotron radiation systems, one per beam, used to measure the transverse bunch distributions. The light emitted by a superconducting undulator and/or by a dipole magnet (depending on beam energy) is intercepted by an extraction mirror in vacuum and sent through a viewport to the imaging Beam Synchrotron Radiation Telescope (BSRT). The first version of the telescope, used from 2009 to mid 2012, was based on spherical focusing mirrors in order to minimize chromatic aberrations. However, this required a very complicated delay line in order to switch the focus between the two different light sources as a function of beam energy. A new system based on optical lenses was designed and installed in mid 2012 in order to simplify the optical line and thus reduce misalignment and focusing errors. The first results with LHC beam using this new system showed a significant reduction in the correction factor required to match the emittance as measured by wire scanners. This contribution discusses the performance of the new optical system, presenting the LHC results and comparing simulations with measurement performed in the laboratory using a BSRT replica.

MOPF29

A Non-Invasive Beam Monitor for Hadron Therapy Beams

proton, CERN, target, vacuum

283

T. Cybulski, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
T. Cybulski, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A. Kacperek, B. Marsland, I. Taylor, A. Wray
The Douglas Cyclotron, The Clatterbridge Cancer Centre NHS Foundation Trust, Wirral, United Kingdom

Funding: Work supported by the EU under contract PITN-GA-2008-215080 and the STFC Cockcroft Institute Core Grant No. ST/G008248/1
Hadron therapy allows for precise dose delivery to the tumour volume only and hence decreases the dose delivered to the nearby organs and healthy tissue. Ideally, the beam would be monitored whilst being delivered to the patient. A novel, real–time and non-interceptive beam monitor for hadron therapy beams has been developed in the QUASAR Group. It is based on the LHCb VErtex LOcator (VELO) detector and couples to the treatment beam’s transverse halo to determine the intensity, position and ultimately the dose of the treatment beam. This contribution presents the design of a stand-alone version of the VELO detector which was developed for the Clatterbridge Cancer Centre (CCC) treatment line. The mechanical and electronic design of the monitor and its data acquisition system are shown, with a focus on the detector positioning and cooling system. Monte Carlo simulations into expected signal distributions are compared against first measurements with the 60 MeV proton beam at CCC.

TUBL3

A Multiband-Instability-Monitor for High-Frequency Intra-Bunch Beam Diagnostics

CERN, SPS, synchrotron, pick-up

327

R.J. Steinhagen
CERN, Geneva, Switzerland
M.J. Boland, T.G. Lucas
The University of Melbourne, Melbourne, Australia

To provide the best possible luminosity, even higher beam intensities are needed in the Large Hadron Collider (LHC) and in its injector chain. This is fundamentally limited by self-amplifying beam instabilities, intrinsic to unavoidable imperfections in accelerators. Traditionally, intra-bunch or head-tail particle motion is measured using fast digitizers, which even using state-of-the-art technology are limited in their effective intra-bunch position resolution to few tens of um in the multi-GHz regime. Oscillations at this scale cause partial or total loss of the beam due to the tight transverse constraints imposed by the LHC collimation system. To improve on the present signal processing, a prototype system has been designed, constructed and tested at the CERN Super-Proton-Synchrotron (SPS) and later on LHC. The system splits the signal into multiple equally-spaced narrow frequency bands that are processed and analysed in parallel. Working with narrow-band signals in frequency-domain permits the use of much higher resolution analogue-to-digital-converters that can be used to resolve nm-scale particle motion already during the onset of instabilities.

Slides TUBL3 [3.165 MB]

TUPF03

Performance Assessment of Wire-Scanners at CERN

SPS, CERN, laser, synchrotron

499

G. Baud, B. Dehning, J. Emery, J-J. Gras, A. Guerrero, E.P. Piselli
CERN, Geneva, Switzerland

This article describes the current fast wire-scanner devices installed in circular accelerators at CERN with an emphasis of the error studies carried out during the last two runs. At present the wire-scanners have similar acquisition systems but are varied in terms of mechanics. Several measurement campaigns were performed aimed at establishing optimal operational settings and to identify and assess systematic errors. In several cases the results led to direct performance improvements while in others this helped in defining the requirements for new detectors.

Poster TUPF03 [1.040 MB]

TUPF29

Tune Measurement from Transverse Feedback Signals in LHC

feedback, transverse, damping, CERN

579

F. Dubouchet, W. Höfle, G. Kotzian, T.E. Levens, D. Valuch
CERN, Geneva, Switzerland
P. Albuquerque
HES-SO//Geneva, Geneva, Switzerland

We show how bunch-by-bunch position data from the LHC transverse feedback system can be used to determine the transverse tunes. Results from machine development experiments are presented and compared with theoretical predictions. In the absence of external beam excitations the tune is visible in the spectra of the position data with the feedback loop as a dip, while with external excitation a peak is visible. Both options, observation with and without excitation, are demonstrated to be complementary. Periodic excitation and observation of the free oscillation can also be used to determine the damping time of the feedback in addition to the coherent tune. Plans are outlined for hardware upgrades of the LHC transverse feedback system that will enable fast online processing of bunch-by-bunch, turn-by-turn data using Graphical Processing Units (GPU). By using GPUs we gain the ability to compute and store the spectrum of all bunches in real-time and the possibility to reconfigure test and deploy algorithms. This data acquisition and analysis architecture also allows changes to be made without disturbing the operation.

Poster TUPF29 [1.052 MB]

WEPC44

Operation of Silicon, Diamond and Liquid Helium Detectors in the Range of Room Temperature to 1.9 Kelvin and After an Irradiation Dose of Several Mega Gray

DIAMOND, proton, beam-losses, CERN

791

C. Kurfuerst, M.R. Bartosik, B. Dehning, T. Eisel, M. Sapinski
CERN, Geneva, Switzerland
V. Eremin
IOFFE, St. Petersburg, Russia

At the triplet magnets close to the interaction regions of the LHC, the current Beam Loss Monitoring system is sensitive to the debris from the collision points. For future beams with higher energy and intensity, the expected increase in luminosity and associated increase of the debris from interaction products is expected to compete with any quench-provoking beam losses from the primary proton beams. In order to distinguish between the two, it is proposed to locate the detectors as close as possible to the superconducting coil. The detectors therefore have to be located inside the cold mass of the superconducting magnets in superfluid helium at 1.9 K. Past measurements have shown that in a liquid helium chamber, diamond and silicon detectors are promising candidates for cryogenic beam loss monitors. This contribution will show the results from new high irradiation beam measurements at both room temperature and 1.9 Kelvin to reveal the radiation tolerance of these different detectors.

WEPC45

Beam Loss Monitoring at the European Spallation Source

beam-losses, ESS, XFEL, simulation

795

L. Tchelidze, H. Hassanzadegan, A. Jansson, M. Jarosz
ESS, Lund, Sweden

At the European Spallation Source proton linear accelerator will generate 5 MW protons to be delivered to a target. This high power accelerator will require significant amount of beam instrumentation, among which the beam loss monitoring system is one of the most important for operation. An LHC type ionization chamber will be used with ~54 uC/Gy sensitivity. At most 1.5 mGy/sec radiation levels are expected close to the beam pipe during normal operation, resulting in up to 80 nA current signal in detectors. Loss monitor electronics is designed to be able to measure currents as little as 1% of the expected current up to as much as 1% of the total beam loss, thus ~800 pA – few mA. In order to study beam loss pattern along the accelerator a coherent model of the whole machine is created for the purposes of Monte Carlo particle transport simulations. Data obtained using the model will be stored in a database together with the initial beam loss conditions. The contents of the database will then be processed using custom neural network algorithms to optimize number and position of the loss monitors and to provide reference on the beam loss localization during operation of the machine.

Poster WEPC45 [1.784 MB]

WEPC46

Beam Delivery Simulation (BDSIM): A Geant4 Based Toolkit for Diagnostics and Loss Simulation

CLIC, simulation, lattice, background

799

S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom
S.T. Boogert, S.M. Gibson, R. Kwee-Hinzmann, L.J. Nevay, J. Snuverink
JAI, Egham, Surrey, United Kingdom
L.C. Deacon
CERN, Geneva, Switzerland

BDSIM is a Geant4 and C++ based particle tracking code which seamlessly tracks particles in accelerators and particle detectors, including the full range of particle interaction physics processes in Geant4. The code has been used to model the backgrounds in the International Linear Collider (ILC), Compact Linear Collider (CLIC), Accelerator Test Facility 2 (ATF2) and more recently the Large Hadron Collider (LHC). This paper outlines the current code and possible example applications and presents a roadmap for future developments.

WEPF29

The LHC Fast Beam Current Change Monitor

injection, CERN, FIR, beam-losses

887

D. Belohrad, J.M. Belleman, L.K. Jensen, M. Krupa, A. Topaloudis
CERN, Geneva, Switzerland

The modularity of the Large Hadron Collider’s (LHC) machine protection system (MPS) allows for the integration of several beam diagnostic instruments. These instruments have not necessarily been designed to have protection functionality, but MPS can still use them to increase the redundancy and reliability of the machine. The LHC fast beam current change monitor (FBCCM) is an example. It is based on analogue signals from fast beam current transformers (FBCT) used nominally to measure the LHC bunch intensities. The FBCCM calculates the magnitude of the beam signal provided by the FBCT, looks for a change over specific time intervals, and triggers a beam dump interlock if losses exceed an energy-dependent threshold. The first prototype of the FBCCM was installed in the LHC during the 2012-2013 run. The aim of this article is to present the FBCCM system and the results obtained, analyse its current performance and provide an outlook for the final system which is expected to be operational after the long LHC shutdown.

THBL1

RF Heating from Wake Losses in Diagnostics Structures

resonance, longitudinal, impedance, simulation

929

E. Métral
CERN, Geneva, Switzerland

Heating of diagnostics structures (striplines, buttons, screen vessels, wire scanners etc) has been observed at many facilities with higher stored currents*. Simulations of wake losses using 3D EM codes are regularly used to estimate the amount of power lost from the bunched beam but on its own this does not tell how much is radiated back into the beam pipe or transmitted into external ports and how much is actually being dissipated in the structure and where. This talk should introduce into the matter, summarise some of the observations at various facilities and illustrate what approaches of detailed simulations have been taken.
* summarizing a workshop at DLS (see http://tinyurl.com/wakeloss )

Slides THBL1 [9.078 MB]