IBIC2012 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOPA01	Design Study of the Striplines for the Extraction Kicker of the CLIC Damping Rings	impedance, kicker, coupling, damping	47
	C. Belver-Aguilar, A. Faus-Golfe IFIC, Valencia, Spain M.J. Barnes CERN, Geneva, Switzerland F. Toral CIEMAT, Madrid, Spain
	Pre-Damping Rings (PDRs) and Damping Rings (DRs) are needed to reduce the beam emittance and, therefore, to achieve the luminosity requirements for the CLIC main linac. Several stripline kicker systems will be used to inject and extract the beam from the PDRs and DRs. Results of initial studies of the stripline cross-section and the beam coupling impedance, for a non-tapered beam pipe, have previously been reported. In this paper, we present the analysis to study the final choice of the cross-section design, based on impedance matching and field inhomogeneity requirements, the power reflected in the transition between an electrode and the input coaxial feedthrough, and the predicted beam coupling impedance. Mechanical tolerances for the stripline manufacturing process are presently being studied. The striplines are planned to be prototyped by December 2012.

MOPA02	270 degree Electron Beam Bending System using Two Sector Magnets for Therapy Application	electron, target, linac, dipole	50
	S.D. Dhole, S. Akhter, V.N. Bhoraskar, B.J. Patil University of Pune, Pune, India S.T. Chavan, R. Krishnan, S.N. Pethe SAMEER, Mumbai, India
	The 270 degree doubly achromatic beam bending magnet system using two sector magnets has been designed mainly for treating cancer and skin diseases. The main requirements of the design of two magnet system is to focus an electron beam having a spot size less than 3 mm X 3 mm, energy spread within 3% and divergence angle <= 3 mrad at the target. To achieve these parameters the simulation was carried out using Lorentz-3EM software. The beam spot, divergence angle and energy spread were observed with respect to the variation in angles of sector magnets and drift distance. From the simulated results, it has been optimized that the first and second magnet has an angle 195 degree and 75 degree and the drift distance 64 mm. It is also observed that at the 1396, 2878 and 4677 A-turn, the optimized design produces 3324, 6221 and 9317 Gauss of magnetic field at median plane require to bend 6, 12 and 18 MeV electron respectively. The output parameters of the optimized design are energy spread 3 %, divergence angle ~ 2.8 mrad and spot size 2.6 mm.

MOPA16	Design and Characterization of a Prototype Stripline Beam Position Monitor for the CLIC Drive Beam	pick-up, damping, impedance, electronics	87
	A. Benot-Morell, L. Søby, M. Wendt CERN, Geneva, Switzerland A. Benot-Morell IFIC, Valencia, Spain J.M. Nappa, J. Tassan-Viol, S. Vilalte IN2P3-LAPP, Annecy-le-Vieux, France S.R. Smith SLAC, Menlo Park, California, USA
	Funding: FPA2010-21456-C02-01, SEIC-2010-00028 The prototype of a stripline Beam Position Monitor (BPM) with its associated readout electronics is under development at CERN, in collaboration with SLAC, LAPP and IFIC. The anticipated position resolution and accuracy are expected to be below 2μm and 20μm respectively for operation of the BPM in the CLIC drive beam (DB) linac. This paper describes the particular CLIC DB conditions with respect to the beam position monitoring, presents the measurement concept, and summarizes electromagnetic simulations and RF measurements performed on the prototype.

MOPA43	RF Front end for High Bandwidth Bunch Arrival Time Monitors in Free-Electron Lasers at DESY	pick-up, operation, electron, laser	157
	A. Penirschke, A. Angelovski, M. Hansli, R. Jakoby TU Darmstadt, Darmstadt, Germany M. Bousonville, M.K. Czwalinna, H. Schlarb, C. Sydlo DESY, Hamburg, Germany A. Kuhl Uni HH, Hamburg, Germany S. Schnepp IFH, Zurich, Switzerland T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Funded by the Federal Ministry of Education and Research (BMBF): 05K10RDA "Weiterentwickung eines Ankunftszeitmonitors" The Free-Electron Laser in Hamburg FLASH is equipped with Bunch Arrival-time Monitors (BAMs) that use an electro-optical detection scheme to modulate the intensity of the femtosecond laser pulse train with the pickup signals (). The achieved resolution of the existing BAMs are less than 10 fs for bunch charges higher than 500 pC. For lower bunch charges the time resolution drops significantly. Increased demands for low bunch charge operation modes of 20 pC and less at FLASH II and the European X-ray Free-Electron Laser XFEL require an upgrade of the existing beam diagnostic equipment. High bandwidth BAMs with newly developed cone-shaped pickups () promise sub-10 fs time resolution for both, the high and low bunch charge operation mode. This paper addresses the RF signal path of the high bandwidth BAMs for FLASH II and XFEL. It comprises radiation resistant coaxial cables, combiners and limiters up to a frequency of 40 GHz from the pickup electrodes to the Electro-optical Mach-Zehnder type modulator (EOM). Detailed investigations of the signal path using measurements and simulations with AWR Microwave Office allows for a good prediction of the signal quality and shape at the EOM. () F. Löhl et al., Phys. Rev. Lett. 104,144801 (2010) (**) A. Angelovski et al. in Proceedings of the International Particle Accelerator Conference (IPAC2011), San Sebastian, Spain, 2011, p.1177

MOPA45	Study of Beam Length Measurement based on TM010 Mode	cavity, coupling, FEL, impedance	162
	R.X. Yuan, Y.B. Leng, L.Y. Yu, W.M. Zhou SINAP, Shanghai, People's Republic of China
	Beam length measurement in frequency domain is a familiar method, and the resolution is seriously limited by the system signal-noise-ratio (SNR) and the beam length measured. Usually this method can only obtain the resolution about ~10ps with beam length ~30ps when using signal from button or stripline BPM. But in FEL case, the beam length is the ps or sub-ps order. The paper discusses the probability of beam length measurement based on the TM010 mode in FEL case. When adopting High Order Mode(HOM) reject and system gain control, the system SNR can arrive at 110dB and the resolution can achieve 30fs with beam length ps or sub-ps.

MOPA46	Realization and Measurements of Cone-shaped Pickups for Bunch Arrival-time Monitors for FLASH and XFEL	pick-up, electron, laser, free-electron-laser	165
	A. Angelovski, M. Hansli, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany M. Bousonville, M.K. Czwalinna, H. Schlarb, C. Sydlo DESY, Hamburg, Germany A. Kuhl Uni HH, Hamburg, Germany S. Schnepp IFH, Zurich, Switzerland T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Funded by the Federal Ministry of Education and Research (BMBF): 05K10RDA "Weiterentwickung eines Ankunftszeitmonitors" At the Free Electron Laser FLASH at DESY, the installed Bunch Arrival-time Monitors (BAMs) use an electro-optical detection scheme for arrival-time measurements. The achieved time resolution is in the sub-10 fs range for bunch charges higher than 500 pC. The extension of FLASH II and the European X-ray Free Electron Laser Project (XFEL) foresees a low charge operation mode with bunch charge of 20 pC or less. The time resolution of the BAMs significantly drops as the bunch charge reduces (). By expanding the bandwidth of the pickups one can increase the time resolution at low charges. In this paper, we present the characterization results of the manufactured cone-shaped pickups introduced in () with a bandwidth up to 40 GHz. The pickups mounted in a vacuum body exhibit four-fold rotational symmetry with respect to the beam pipe. Due to different beam pipe apertures for FLASH and XFEL, two bodies are manufactured. The rf properties of the mounted pickups in case of open and sealed body as well as the pickups separately are measured and compared to the simulation results obtained by CST STUDIO SUITE®. ()M. K. Bock et al. in Proceedings of DIPAC 2011, Hamburg, Germany, 2011, p.365 (**)A. Angelovski et al. in Proceedings of IPAC 2011, San Sebastian, Spain, 2011, p.1177

MOPA47	Planar Transmission Line BPM for Horizontal Aperture Chicane for XFEL	pick-up, electron, electronics, kicker	168
	A. Angelovski, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany C. Gerth, U. Mavrič, C. Sydlo DESY, Hamburg, Germany
	In order to obtain ultra-short bunches in the Free Electron Laser FLASH at DESY, the electron beam is compressed in magnetic chicanes. Precise knowledge of the beam position in the chicane is of great significance for the longitudinal dynamics control. In the current implementation cylindrical pickup-striplines mounted perpendicularly to the beam are used as a Beam Position Monitor (BPM)(). One can determine the horizontal beam position by measuring the phase difference of the beam induced signal at opposite ends of a pickup. Due to the different electrical and mechanical requirements for the European XFEL a new BPM has to be developed. In this paper, we present the design and analysis of a planar transmission line structure which is planned to be used as a BPM in the European XFEL. The planar design of the pickups can provide for proper impedance match to the subsequent electronics as well as sufficient mechanical stability along the aperture when using alumina substrates. A scaled non-hermetic prototype of the BPM is built and characterized by scattering parameters. The measurement results are compared to simulations obtained by CST STUDIO SUITE®. () K. Hacker at el, Proceedings of DIPAC 2007, Venice, Italy 2007, p.108

MOPB50	Design and Operation of the High Intensity Luminosity Monitors of the LHC	detector, luminosity, operation, neutron	179
	H.S. Matis, S.C. Hedges, M. Placidi, A. Ratti, W.C. Turner LBNL, Berkeley, California, USA E. Bravin CERN, Geneva, Switzerland R. Miyamoto ESS, Lund, Sweden
	Funding: We acknowledge the US-LARP program that is sponsoring this work and NERSC, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We have built a high-pressure ionization chamber (BRAN) for the IP1 (ATLAS) and IP5 (CMS) regions of the LHC. This chamber is designed to measure the relative bunch-by-bunch collision rate of the LHC from 10²⁸ cm^-2s⁻¹ during beam commissioning all the way up to the expected full luminosity of 10³⁴ cm^-2s⁻¹ at 7.0 TeV. These high-pressure ionization chambers measure the intensity of hadronic/electromagnetic showers produced by the forward neutral particles of LHC collisions. They are designed to withstand the high radiation produced by these forward collisions and are currently used in LHC operations. This paper covers the detector's design and performance in measuring both pp and PbPb collisions during LHC operation, including a comparison with the ATLAS and CMS luminosity measurements. The work also includes modeling of the detectors and the ability to predict how the detector will respond to the higher energy and intensity operation of the LHC with different operating modes involving both ions and protons.

MOPB55	Electron Cloud Measurements using Shielded Pickups at CesrTA	electron, detector, pick-up, synchrotron	198
	J.P. Sikora, J.A. Crittenden, J.S. Ginsberg, D. L. Rubin CLASSE, Ithaca, New York, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. The Cornell storage ring was originally a positron/electron collider with beam energies ranging from 2 to 5 GeV. In 2008 it was reconfigured as the Cornell Electron Storage Ring Test Accelerator (CesrTA). An important part of the research at CesrTA is the study of the growth, decay and mitigation of electron clouds. Electron Cloud (EC) densities can be measured with a Shielded Pickup (SPU), where cloud electrons pass into the detector through an array of small holes in the wall of the beam-pipe. The signals produced by SPU have proved to be very useful in measuring the mitigating effect of different vacuum chamber surfaces - including differences in quantum efficiency as well as secondary and elastic yield. This has been accomplished through the careful comparison of observed signals with the output of the EC simulation code ECLOUD. We present example comparisons of data and simulation that show the effect of different surfaces as well as beam conditioning effects. In addition, some data has been acquired using a solenoid to produce a longitudinal magnetic field at the SPU. We will present our current understanding of the effect of a longitudinal magnetic field on SPU signals.

MOPB65	Measurement of Sub-picosecond Bunch Length with the Interferometry from Double Diffraction Radiation Target	radiation, electron, target, detector	218
	G.A. Naumenko, A. Potylitsyn, M.V. Shevelev, D.A. Shkitov TPU, Tomsk, Russia H.X. Deng, S.L. Lu, T. Yu, J.B. Zhang SINAP, Shanghai, People's Republic of China
	Funding: This work was supported by the joint Russian-Chinese grant (RFBR N 110291177 and NSFC N 11111120065) and partially by the Program of Russian MES 'Nauka' and Chinese NSFC grant N 11175240. Reliable and precise methods for non-invasive diagnostics of sub-picosecond electron bunches are required for new accelerator facilities (FEL, LWFA, et al.). Measurements of spectral characteristics of coherent radiation generated by such bunches using interferometer allow to determine a bunch length [1]. The interference pattern obtained by two diffraction radiation (DR) beams from two shifted plates (double DR target) may be used instead an interferometer [2]. Recently the coherent DR interferometry scheme at the SINAP accelerator facility was established [3]. Here we report the results of comparing the first measurement from such a technique with the measurement from Michelson interferometer. The parameters of fs linac are described in [4]. The DR target was consisted of two plates made from aluminum foil. The pyroelectric detector SPI-D-62 was used. The analysis of results from two techniques gives the same estimated bunch length about 660 fs (0.2 mm), which confirms the ability of the proposed technique for non-invasive bunch length measurements in the sub-picosecond range without a complicated scheme like Michelson interferometer or similar. 1. Murokh A.et al.,NIMA 410(1998)452 2. Potylitsyn A.P.,NIMB 227(2005)191 3. Shevelev M. et al.,Journal of Physics: Conference Series 357(2012) 4. Lin X.et al., Chin. Phys. Lett.27,4(2010)044101

TUTA02	BPM Electrode and High Power Feedthrough - Special Topics in Wideband Feedthrough	vacuum, impedance, kicker, linac	297
	M. Tobiyama KEK, Ibaraki, Japan
	Since most of the beam in accelerator runs in the vacuum chamber made of metal, it is needed to have 'feedthrough' to get or to put the RF signal from or to beam. For example, we can get the beam signal by using button-type electrode which have electrical isolation material to seal the vacuum. Now, many types of vacuum feedthrough with coaxial structure are available commercially. Nevertheless, it is meaningful to understand the design principle of the feedthough needed for the beam instrumentation, especially for short bunch length, high beam current machine. I will show the design method of the feedthrough such as BPM electrodes or high power feedthroughs using 3D EM-codes such as HFSS or GdfidL based on several examples developed for SuperKEKB accelerators.
	Slides TUTA02 [6.806 MB]

TUPA22	Design of RF Front End for Cavity Beam Position Monitor based on ICs	cavity, embedded, FPGA, FEL	383
	B.P. Wang, Z.C. Chen, Y.B. Leng, L.Y. Yu, R.X. Yuan, W.M. Zhou SINAP, Shanghai, People's Republic of China
	RF front end has the significant impact on the performance of cavity beam position monitor (CBPM) which is indispensable beam instrumentation component in free electron laser(FEL) or linear collider facility. With many new advances in data converter and radio technology, complex RF front end design has been greatly simplified. Now based on digital intermediate frequency (IF) receiver architecture, a new RF front end for (CBPM) has been designed and fabricated using surface mount component on print circuit board (PCB). The front end contains analog-digital converter used to digitize the IF signals. The whole system would be integrated to a digital board developed by our lab to produce the dedicated signal processor for CBPM. There is an Xilinx Vertex-5 FPGA device on the digital board and relevant signal processing algorithm has been implemented on it using VHDL. The details about design and test results would be introduced blow.

TUPA31	A Real-Time FPGA Based Algorithm for the Combination of Beam Loss Acquisition Methods used for Measurement Dynamic Range Expansion	FPGA, monitoring, operation, embedded	419
	M. Kwiatkowski, M. Alsdorf, B. Dehning, W. Viganò, C. Zamantzas CERN, Geneva, Switzerland
	The aim of the Beam Loss Monitoring Dual Polarity (BLEDP) module under development at the European Organisation for Nuclear Research (CERN) is to measure and digitise with high precision the current produced by several types of beam loss detectors. The BLEDP module consists of eight analogue channels each with a fully differential integrator and an accompanying 16 bit ADC at the output of each analogue integrator. The on-board FPGA device controls the integral periods, instructs the ADC devices to perform measurements at the end of each period and collects the measurements. In the next stage it combines the number of charge and discharge cycles accounted in the last interval together with the cycle fractions observed using the ADC samples to produce a digitized high precision value of the charges collected. This paper describes briefly the principle of the fully differential integrator and focuses on the algorithm employed to process the digital data.

TUPA34	Inverse Response Matrix Computation for the Storage Ring Slow Orbit Feedback Control: Synthesized Topological Inversion Computation	feedback, controls, closed-orbit, betatron	431
	J.M. Lee, J.Y. Huang, C. Kim PAL, Pohang, Kyungbuk, Republic of Korea
	Using the derivative response matrix between BPM-data and MPS-setting, we described the inverse computation methodology for the storage ring orbit feedback control. Practically useful for SOFB with assistance of FOFB, the inverse of SVD manipulation is less efficient because a type of consecutive instability noise irreversibly accumulates in the beam trajectory deviation. In contrast, a novel numerical recipe based on topological math can lead to a self-consistent solution, dramatically suppressing ill-posed instability problems. This approach, known as a singularity regularization method, makes it feasible to compute a system-matched de-noising filter. The response matrix in H/V dimensions reflects a global beam dynamics along the storage ring lattices. Matrix refinement manipulatcan can be made to filter out the uncertainty of measurement errors escaping from beam dynamics constraints. Then we believe that algorithm filter can be effective as a software part of FOFB control. Our math STIC (Synthesized Topological Inversion Computation) appears to be the most reliable inverse computation methodology. Our PLS-2 response matrix will be presented to explain our ORBIT-STIC test. Jay Min Lee et al, presented at the 15th International Conference on X-ray Absorption Fine Structure, Beijing, July 22-28, 2012.

TUPB49	Electron Cloud Density Measurements using Resonant TE Waves at CesrTA	resonance, electron, storage-ring, positron	471
	J.P. Sikora, M.G. Billing, D.O. Duggins, Y. Li, D. L. Rubin, R.M. Schwartz, K.G. Sonnad CLASSE, Ithaca, New York, USA S. De Santis LBNL, Berkeley, California, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. The Cornell Electron Storage Ring has been reconfigured as a test accelerator (CesrTA) with beam energies ranging from 2 GeV to 5 GeV of either positrons or electrons. Research at CesrTA includes the study of the growth, decay and mitigation of electron clouds in the storage ring. Electron Cloud (EC) densities can be measured by resonantly exciting the beam-pipe with microwaves. The EC density will change beam-pipe's resonant frequency by an amount that is proportional to the local electric field squared of the standing waves. When the EC density is not uniform, it is especially important to know the standing wave pattern in order to obtain an absolute EC density measurement. We will present our current understanding of this technique in the context of new test sections of beam-pipe installed in August 2012. This will include bench measurements of standing waves in the beam-pipe, simulations of this geometry and recent EC density measurements with beam.

TUPB69	Numerical Analysis on the Gain-reduction Characteristics of Multi-wire Proportional Chambers	ion, electron, cathode, space-charge	502
	K. Katagiri, T. Furukawa, K. Noda NIRS, Chiba-shi, Japan
	Several MWPC (Multi-Wire Proportional Chamber) monitors are installed to diagnosis the beam profiles in the high-energy beam transport at HIMAC (Heavy Ion Medical Accelerator in Chiba) synchrotrons. When the intensity of the incident beams are much high, the gain reduction of the output signal from the MWPC monitor occurs due to the space charge effect of positive ions around the anode wires. The gain reduction is expected to be improved by changing geometric parameters, such as anode radius and distance between electrodes. In order to investigate the gain-reduction characteristics for different geometric parameters, we performed numerical simulation using a numerical code. The numerical code was developed using a two-dimensional drift-diffusion model to evaluate the gas gain including the reduction effect caused by the space charge effect of the moving positive ions. We investigate the gain-reduction rate for several parameters of the anode distance when changing the beam intensity. From these results, we discuss desirable distances between the anode wires to improve the gain reduction.

TUPB74	Diamond Mirrors for the SuperKEKB Synchtron Radiation Monitor	extraction, synchrotron, synchrotron-radiation, radiation	515
	J.W. Flanagan, A. Arinaga, H. Fukuma, H. Ikeda KEK, Ibaraki, Japan
	The SuperKEKB accelerator, a 40x luminosity upgrade to the KEKB accelerator, will be a high-current, low-emittance double ring collider. The beryllium primary extraction mirrors used for the synchrotron radiation monitors at KEKB suffered from heat distortion due to incident synchrotron radiation, leading to systematic changes in magnification with beam current and necessitating continuous monitoring and compensation of such distortions in order to correctly measure the beam sizes. The heat loads on the extraction mirrors will be higher at SuperKEKB, with heat-induced magnification changes up to 40% expected if the same mirrors were used as at KEKB. We are working on a design based on mirrors made of quasi-monocrystalline diamond, which has much higher heat conductance and a lower thermal expansion coefficient than beryllium. With such mirrors it is targeted to reduce the beam current-dependent magnification effects to the level of a few percent at SuperKEKB. Measurements of heat-induced deformations on fabricated prototype mirrors will be presented, along with comparisons with the results of numerical simulations.

Paper

Title

Other Keywords

Page

MOPA01

Design Study of the Striplines for the Extraction Kicker of the CLIC Damping Rings

impedance, kicker, coupling, damping

47

C. Belver-Aguilar, A. Faus-Golfe
IFIC, Valencia, Spain
M.J. Barnes
CERN, Geneva, Switzerland
F. Toral
CIEMAT, Madrid, Spain

Pre-Damping Rings (PDRs) and Damping Rings (DRs) are needed to reduce the beam emittance and, therefore, to achieve the luminosity requirements for the CLIC main linac. Several stripline kicker systems will be used to inject and extract the beam from the PDRs and DRs. Results of initial studies of the stripline cross-section and the beam coupling impedance, for a non-tapered beam pipe, have previously been reported. In this paper, we present the analysis to study the final choice of the cross-section design, based on impedance matching and field inhomogeneity requirements, the power reflected in the transition between an electrode and the input coaxial feedthrough, and the predicted beam coupling impedance. Mechanical tolerances for the stripline manufacturing process are presently being studied. The striplines are planned to be prototyped by December 2012.

MOPA02

270 degree Electron Beam Bending System using Two Sector Magnets for Therapy Application

electron, target, linac, dipole

50

S.D. Dhole, S. Akhter, V.N. Bhoraskar, B.J. Patil
University of Pune, Pune, India
S.T. Chavan, R. Krishnan, S.N. Pethe
SAMEER, Mumbai, India

The 270 degree doubly achromatic beam bending magnet system using two sector magnets has been designed mainly for treating cancer and skin diseases. The main requirements of the design of two magnet system is to focus an electron beam having a spot size less than 3 mm X 3 mm, energy spread within 3% and divergence angle <= 3 mrad at the target. To achieve these parameters the simulation was carried out using Lorentz-3EM software. The beam spot, divergence angle and energy spread were observed with respect to the variation in angles of sector magnets and drift distance. From the simulated results, it has been optimized that the first and second magnet has an angle 195 degree and 75 degree and the drift distance 64 mm. It is also observed that at the 1396, 2878 and 4677 A-turn, the optimized design produces 3324, 6221 and 9317 Gauss of magnetic field at median plane require to bend 6, 12 and 18 MeV electron respectively. The output parameters of the optimized design are energy spread 3 %, divergence angle ~ 2.8 mrad and spot size 2.6 mm.

MOPA16

Design and Characterization of a Prototype Stripline Beam Position Monitor for the CLIC Drive Beam

pick-up, damping, impedance, electronics

87

A. Benot-Morell, L. Søby, M. Wendt
CERN, Geneva, Switzerland
A. Benot-Morell
IFIC, Valencia, Spain
J.M. Nappa, J. Tassan-Viol, S. Vilalte
IN2P3-LAPP, Annecy-le-Vieux, France
S.R. Smith
SLAC, Menlo Park, California, USA

Funding: FPA2010-21456-C02-01, SEIC-2010-00028
The prototype of a stripline Beam Position Monitor (BPM) with its associated readout electronics is under development at CERN, in collaboration with SLAC, LAPP and IFIC. The anticipated position resolution and accuracy are expected to be below 2μm and 20μm respectively for operation of the BPM in the CLIC drive beam (DB) linac. This paper describes the particular CLIC DB conditions with respect to the beam position monitoring, presents the measurement concept, and summarizes electromagnetic simulations and RF measurements performed on the prototype.

MOPA43

RF Front end for High Bandwidth Bunch Arrival Time Monitors in Free-Electron Lasers at DESY

pick-up, operation, electron, laser

157

A. Penirschke, A. Angelovski, M. Hansli, R. Jakoby
TU Darmstadt, Darmstadt, Germany
M. Bousonville, M.K. Czwalinna, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany
A. Kuhl
Uni HH, Hamburg, Germany
S. Schnepp
IFH, Zurich, Switzerland
T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Funded by the Federal Ministry of Education and Research (BMBF): 05K10RDA "Weiterentwickung eines Ankunftszeitmonitors"
The Free-Electron Laser in Hamburg FLASH is equipped with Bunch Arrival-time Monitors (BAMs) that use an electro-optical detection scheme to modulate the intensity of the femtosecond laser pulse train with the pickup signals (*). The achieved resolution of the existing BAMs are less than 10 fs for bunch charges higher than 500 pC. For lower bunch charges the time resolution drops significantly. Increased demands for low bunch charge operation modes of 20 pC and less at FLASH II and the European X-ray Free-Electron Laser XFEL require an upgrade of the existing beam diagnostic equipment. High bandwidth BAMs with newly developed cone-shaped pickups (**) promise sub-10 fs time resolution for both, the high and low bunch charge operation mode. This paper addresses the RF signal path of the high bandwidth BAMs for FLASH II and XFEL. It comprises radiation resistant coaxial cables, combiners and limiters up to a frequency of 40 GHz from the pickup electrodes to the Electro-optical Mach-Zehnder type modulator (EOM). Detailed investigations of the signal path using measurements and simulations with AWR Microwave Office allows for a good prediction of the signal quality and shape at the EOM.
(*) F. Löhl et al., Phys. Rev. Lett. 104,144801 (2010)
(**) A. Angelovski et al. in Proceedings of the International Particle Accelerator Conference (IPAC2011), San Sebastian, Spain, 2011, p.1177

MOPA45

Study of Beam Length Measurement based on TM010 Mode

cavity, coupling, FEL, impedance

162

R.X. Yuan, Y.B. Leng, L.Y. Yu, W.M. Zhou
SINAP, Shanghai, People's Republic of China

Beam length measurement in frequency domain is a familiar method, and the resolution is seriously limited by the system signal-noise-ratio (SNR) and the beam length measured. Usually this method can only obtain the resolution about ~10ps with beam length ~30ps when using signal from button or stripline BPM. But in FEL case, the beam length is the ps or sub-ps order. The paper discusses the probability of beam length measurement based on the TM010 mode in FEL case. When adopting High Order Mode(HOM) reject and system gain control, the system SNR can arrive at 110dB and the resolution can achieve 30fs with beam length ps or sub-ps.

MOPA46

Realization and Measurements of Cone-shaped Pickups for Bunch Arrival-time Monitors for FLASH and XFEL

pick-up, electron, laser, free-electron-laser

165

A. Angelovski, M. Hansli, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
M. Bousonville, M.K. Czwalinna, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany
A. Kuhl
Uni HH, Hamburg, Germany
S. Schnepp
IFH, Zurich, Switzerland
T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Funded by the Federal Ministry of Education and Research (BMBF): 05K10RDA "Weiterentwickung eines Ankunftszeitmonitors"
At the Free Electron Laser FLASH at DESY, the installed Bunch Arrival-time Monitors (BAMs) use an electro-optical detection scheme for arrival-time measurements. The achieved time resolution is in the sub-10 fs range for bunch charges higher than 500 pC. The extension of FLASH II and the European X-ray Free Electron Laser Project (XFEL) foresees a low charge operation mode with bunch charge of 20 pC or less. The time resolution of the BAMs significantly drops as the bunch charge reduces (*). By expanding the bandwidth of the pickups one can increase the time resolution at low charges. In this paper, we present the characterization results of the manufactured cone-shaped pickups introduced in (**) with a bandwidth up to 40 GHz. The pickups mounted in a vacuum body exhibit four-fold rotational symmetry with respect to the beam pipe. Due to different beam pipe apertures for FLASH and XFEL, two bodies are manufactured. The rf properties of the mounted pickups in case of open and sealed body as well as the pickups separately are measured and compared to the simulation results obtained by CST STUDIO SUITE®.
(*)M. K. Bock et al. in Proceedings of DIPAC 2011, Hamburg, Germany, 2011, p.365
(**)A. Angelovski et al. in Proceedings of IPAC 2011, San Sebastian, Spain, 2011, p.1177

MOPA47

Planar Transmission Line BPM for Horizontal Aperture Chicane for XFEL

pick-up, electron, electronics, kicker

168

A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
C. Gerth, U. Mavrič, C. Sydlo
DESY, Hamburg, Germany

In order to obtain ultra-short bunches in the Free Electron Laser FLASH at DESY, the electron beam is compressed in magnetic chicanes. Precise knowledge of the beam position in the chicane is of great significance for the longitudinal dynamics control. In the current implementation cylindrical pickup-striplines mounted perpendicularly to the beam are used as a Beam Position Monitor (BPM)(*). One can determine the horizontal beam position by measuring the phase difference of the beam induced signal at opposite ends of a pickup. Due to the different electrical and mechanical requirements for the European XFEL a new BPM has to be developed. In this paper, we present the design and analysis of a planar transmission line structure which is planned to be used as a BPM in the European XFEL. The planar design of the pickups can provide for proper impedance match to the subsequent electronics as well as sufficient mechanical stability along the aperture when using alumina substrates. A scaled non-hermetic prototype of the BPM is built and characterized by scattering parameters. The measurement results are compared to simulations obtained by CST STUDIO SUITE®.
(*) K. Hacker at el, Proceedings of DIPAC 2007, Venice, Italy 2007, p.108

MOPB50

Design and Operation of the High Intensity Luminosity Monitors of the LHC

detector, luminosity, operation, neutron

179

H.S. Matis, S.C. Hedges, M. Placidi, A. Ratti, W.C. Turner
LBNL, Berkeley, California, USA
E. Bravin
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

Funding: We acknowledge the US-LARP program that is sponsoring this work and NERSC, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
We have built a high-pressure ionization chamber (BRAN) for the IP1 (ATLAS) and IP5 (CMS) regions of the LHC. This chamber is designed to measure the relative bunch-by-bunch collision rate of the LHC from 10²⁸ cm^-2s⁻¹ during beam commissioning all the way up to the expected full luminosity of 10³⁴ cm^-2s⁻¹ at 7.0 TeV. These high-pressure ionization chambers measure the intensity of hadronic/electromagnetic showers produced by the forward neutral particles of LHC collisions. They are designed to withstand the high radiation produced by these forward collisions and are currently used in LHC operations. This paper covers the detector's design and performance in measuring both pp and PbPb collisions during LHC operation, including a comparison with the ATLAS and CMS luminosity measurements. The work also includes modeling of the detectors and the ability to predict how the detector will respond to the higher energy and intensity operation of the LHC with different operating modes involving both ions and protons.

MOPB55

Electron Cloud Measurements using Shielded Pickups at CesrTA

electron, detector, pick-up, synchrotron

198

J.P. Sikora, J.A. Crittenden, J.S. Ginsberg, D. L. Rubin
CLASSE, Ithaca, New York, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
The Cornell storage ring was originally a positron/electron collider with beam energies ranging from 2 to 5 GeV. In 2008 it was reconfigured as the Cornell Electron Storage Ring Test Accelerator (CesrTA). An important part of the research at CesrTA is the study of the growth, decay and mitigation of electron clouds. Electron Cloud (EC) densities can be measured with a Shielded Pickup (SPU), where cloud electrons pass into the detector through an array of small holes in the wall of the beam-pipe. The signals produced by SPU have proved to be very useful in measuring the mitigating effect of different vacuum chamber surfaces - including differences in quantum efficiency as well as secondary and elastic yield. This has been accomplished through the careful comparison of observed signals with the output of the EC simulation code ECLOUD. We present example comparisons of data and simulation that show the effect of different surfaces as well as beam conditioning effects. In addition, some data has been acquired using a solenoid to produce a longitudinal magnetic field at the SPU. We will present our current understanding of the effect of a longitudinal magnetic field on SPU signals.

MOPB65

Measurement of Sub-picosecond Bunch Length with the Interferometry from Double Diffraction Radiation Target

radiation, electron, target, detector

218

G.A. Naumenko, A. Potylitsyn, M.V. Shevelev, D.A. Shkitov
TPU, Tomsk, Russia
H.X. Deng, S.L. Lu, T. Yu, J.B. Zhang
SINAP, Shanghai, People's Republic of China

Funding: This work was supported by the joint Russian-Chinese grant (RFBR N 110291177 and NSFC N 11111120065) and partially by the Program of Russian MES 'Nauka' and Chinese NSFC grant N 11175240.
Reliable and precise methods for non-invasive diagnostics of sub-picosecond electron bunches are required for new accelerator facilities (FEL, LWFA, et al.). Measurements of spectral characteristics of coherent radiation generated by such bunches using interferometer allow to determine a bunch length [1]. The interference pattern obtained by two diffraction radiation (DR) beams from two shifted plates (double DR target) may be used instead an interferometer [2]. Recently the coherent DR interferometry scheme at the SINAP accelerator facility was established [3]. Here we report the results of comparing the first measurement from such a technique with the measurement from Michelson interferometer. The parameters of fs linac are described in [4]. The DR target was consisted of two plates made from aluminum foil. The pyroelectric detector SPI-D-62 was used. The analysis of results from two techniques gives the same estimated bunch length about 660 fs (0.2 mm), which confirms the ability of the proposed technique for non-invasive bunch length measurements in the sub-picosecond range without a complicated scheme like Michelson interferometer or similar.
1. Murokh A.et al.,NIMA 410(1998)452
2. Potylitsyn A.P.,NIMB 227(2005)191
3. Shevelev M. et al.,Journal of Physics: Conference Series 357(2012)
4. Lin X.et al., Chin. Phys. Lett.27,4(2010)044101

TUTA02

BPM Electrode and High Power Feedthrough - Special Topics in Wideband Feedthrough

vacuum, impedance, kicker, linac

297

M. Tobiyama
KEK, Ibaraki, Japan

Since most of the beam in accelerator runs in the vacuum chamber made of metal, it is needed to have 'feedthrough' to get or to put the RF signal from or to beam. For example, we can get the beam signal by using button-type electrode which have electrical isolation material to seal the vacuum. Now, many types of vacuum feedthrough with coaxial structure are available commercially. Nevertheless, it is meaningful to understand the design principle of the feedthough needed for the beam instrumentation, especially for short bunch length, high beam current machine. I will show the design method of the feedthrough such as BPM electrodes or high power feedthroughs using 3D EM-codes such as HFSS or GdfidL based on several examples developed for SuperKEKB accelerators.

Slides TUTA02 [6.806 MB]

TUPA22

Design of RF Front End for Cavity Beam Position Monitor based on ICs

cavity, embedded, FPGA, FEL

383

B.P. Wang, Z.C. Chen, Y.B. Leng, L.Y. Yu, R.X. Yuan, W.M. Zhou
SINAP, Shanghai, People's Republic of China

RF front end has the significant impact on the performance of cavity beam position monitor (CBPM) which is indispensable beam instrumentation component in free electron laser(FEL) or linear collider facility. With many new advances in data converter and radio technology, complex RF front end design has been greatly simplified. Now based on digital intermediate frequency (IF) receiver architecture, a new RF front end for (CBPM) has been designed and fabricated using surface mount component on print circuit board (PCB). The front end contains analog-digital converter used to digitize the IF signals. The whole system would be integrated to a digital board developed by our lab to produce the dedicated signal processor for CBPM. There is an Xilinx Vertex-5 FPGA device on the digital board and relevant signal processing algorithm has been implemented on it using VHDL. The details about design and test results would be introduced blow.

TUPA31

A Real-Time FPGA Based Algorithm for the Combination of Beam Loss Acquisition Methods used for Measurement Dynamic Range Expansion

FPGA, monitoring, operation, embedded

419

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

The aim of the Beam Loss Monitoring Dual Polarity (BLEDP) module under development at the European Organisation for Nuclear Research (CERN) is to measure and digitise with high precision the current produced by several types of beam loss detectors. The BLEDP module consists of eight analogue channels each with a fully differential integrator and an accompanying 16 bit ADC at the output of each analogue integrator. The on-board FPGA device controls the integral periods, instructs the ADC devices to perform measurements at the end of each period and collects the measurements. In the next stage it combines the number of charge and discharge cycles accounted in the last interval together with the cycle fractions observed using the ADC samples to produce a digitized high precision value of the charges collected. This paper describes briefly the principle of the fully differential integrator and focuses on the algorithm employed to process the digital data.

TUPA34

Inverse Response Matrix Computation for the Storage Ring Slow Orbit Feedback Control: Synthesized Topological Inversion Computation

feedback, controls, closed-orbit, betatron

431

J.M. Lee, J.Y. Huang, C. Kim
PAL, Pohang, Kyungbuk, Republic of Korea

Using the derivative response matrix between BPM-data and MPS-setting, we described the inverse computation methodology for the storage ring orbit feedback control. Practically useful for SOFB with assistance of FOFB, the inverse of SVD manipulation is less efficient because a type of consecutive instability noise irreversibly accumulates in the beam trajectory deviation. In contrast, a novel numerical recipe based on topological math can lead to a self-consistent solution, dramatically suppressing ill-posed instability problems. This approach, known as a singularity regularization method, makes it feasible to compute a system-matched de-noising filter. The response matrix in H/V dimensions reflects a global beam dynamics along the storage ring lattices. Matrix refinement manipulatcan can be made to filter out the uncertainty of measurement errors escaping from beam dynamics constraints. Then we believe that algorithm filter can be effective as a software part of FOFB control. Our math STIC (Synthesized Topological Inversion Computation*) appears to be the most reliable inverse computation methodology. Our PLS-2 response matrix will be presented to explain our ORBIT-STIC test.
* Jay Min Lee et al, presented at the 15th International Conference on X-ray Absorption Fine Structure, Beijing, July 22-28, 2012.

TUPB49

Electron Cloud Density Measurements using Resonant TE Waves at CesrTA

resonance, electron, storage-ring, positron

471

J.P. Sikora, M.G. Billing, D.O. Duggins, Y. Li, D. L. Rubin, R.M. Schwartz, K.G. Sonnad
CLASSE, Ithaca, New York, USA
S. De Santis
LBNL, Berkeley, California, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
The Cornell Electron Storage Ring has been reconfigured as a test accelerator (CesrTA) with beam energies ranging from 2 GeV to 5 GeV of either positrons or electrons. Research at CesrTA includes the study of the growth, decay and mitigation of electron clouds in the storage ring. Electron Cloud (EC) densities can be measured by resonantly exciting the beam-pipe with microwaves. The EC density will change beam-pipe's resonant frequency by an amount that is proportional to the local electric field squared of the standing waves. When the EC density is not uniform, it is especially important to know the standing wave pattern in order to obtain an absolute EC density measurement. We will present our current understanding of this technique in the context of new test sections of beam-pipe installed in August 2012. This will include bench measurements of standing waves in the beam-pipe, simulations of this geometry and recent EC density measurements with beam.

TUPB69

Numerical Analysis on the Gain-reduction Characteristics of Multi-wire Proportional Chambers

ion, electron, cathode, space-charge

502

K. Katagiri, T. Furukawa, K. Noda
NIRS, Chiba-shi, Japan

Several MWPC (Multi-Wire Proportional Chamber) monitors are installed to diagnosis the beam profiles in the high-energy beam transport at HIMAC (Heavy Ion Medical Accelerator in Chiba) synchrotrons. When the intensity of the incident beams are much high, the gain reduction of the output signal from the MWPC monitor occurs due to the space charge effect of positive ions around the anode wires. The gain reduction is expected to be improved by changing geometric parameters, such as anode radius and distance between electrodes. In order to investigate the gain-reduction characteristics for different geometric parameters, we performed numerical simulation using a numerical code. The numerical code was developed using a two-dimensional drift-diffusion model to evaluate the gas gain including the reduction effect caused by the space charge effect of the moving positive ions. We investigate the gain-reduction rate for several parameters of the anode distance when changing the beam intensity. From these results, we discuss desirable distances between the anode wires to improve the gain reduction.

TUPB74

Diamond Mirrors for the SuperKEKB Synchtron Radiation Monitor

extraction, synchrotron, synchrotron-radiation, radiation

515

J.W. Flanagan, A. Arinaga, H. Fukuma, H. Ikeda
KEK, Ibaraki, Japan

The SuperKEKB accelerator, a 40x luminosity upgrade to the KEKB accelerator, will be a high-current, low-emittance double ring collider. The beryllium primary extraction mirrors used for the synchrotron radiation monitors at KEKB suffered from heat distortion due to incident synchrotron radiation, leading to systematic changes in magnification with beam current and necessitating continuous monitoring and compensation of such distortions in order to correctly measure the beam sizes. The heat loads on the extraction mirrors will be higher at SuperKEKB, with heat-induced magnification changes up to 40% expected if the same mirrors were used as at KEKB. We are working on a design based on mirrors made of quasi-monocrystalline diamond, which has much higher heat conductance and a lower thermal expansion coefficient than beryllium. With such mirrors it is targeted to reduce the beam current-dependent magnification effects to the level of a few percent at SuperKEKB. Measurements of heat-induced deformations on fabricated prototype mirrors will be presented, along with comparisons with the results of numerical simulations.