| Paper | Title | Page |
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| MOPME003 | Development of Diamond Sensors for Beam Halo and Compton Spectrum Diagnostics After The Interaction Point of ATF2 | 470 |
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| ATF2 is a low energy (1.3GeV) prototype of the final focus system for ILC and CLIC linear collider projects. A major issue at ATF2 and in linear colliders is to control the beam halo, which consists of tails extending far beyond the Gaussian core of the beam. At present there is no dedicated collimation for the beam halo at ATF2, and the transverse distribution near the interaction point is not well known. The development of a sensor based on CVD diamond to scan the beam halo in the vacuum chamber a few meters after the interaction point is presented. This system also aims to detect the Compton recoil electrons generated by the laser interferometer (Shintake monitor) used to measure the beam size at the interaction point of ATF2. | ||
| MOPME004 | Fast Luminosity Monitoring using Diamond Sensors for Super Flavour Factories | 473 |
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| Super flavour factories aim to reach very high luminosities thanks to a new concept whereby the ultra-low emittance beams collide with a large crossing angle. Fast luminosity measurements are needed as input to luminosity optimization and feedback in the presence of dynamic imperfections. The required small relative precision can be reached exploiting the very large cross section of the radiative Bhabha process at zero photon scattering angle. The instrumental technique selected to sustain the large particle fluxes is based on diamond sensors to be positioned via moveable stages immediately outside the beam pipe, at locations chosen to minimize the contamination from other particle loss mechanisms. | ||
| MOPME005 | Goubau Line and Beam Characterization of TURBO-ICT for SwissFEL | 476 |
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| SwissFEL will be able to operate with electron bunch doublets 28ns apart. Each of the bunches carries 10pC to 200pC of charge with bunch lengths of a few femto-seconds. For charge calibration of the FEL photon pulses, a measurement accuracy of 1% is desired. The Turbo-ICT accomplishes these requirements with negligible beam position and bunch length dependence. It is insensitive to dark current and features high immunity to background noise. We characterize the Turbo-ICT performance on a Goubau line, also known as single-wire transmission line. The Goubau line utilizes electromagnetic fields with frequencies up to many GHz. It allows accurate bench testing including beam position and bunch length dependence. The results are compared to beam measurements performed at the SwissFEL Injector Test Facility (SITF). | ||
| MOPME006 | The New Orbit Correction System at ELSA | 479 |
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| ELSA is a fast ramping stretcher ring currently supplying polarized electrons with energies up to 2.4 GeV. To preserve the degree of polarization, the vertical orbit needs to be continuously corrected during beam acceleration. The acceleration is usually performed within 300 ms, with a maximum ramping speed of 6 GeV/s. We aim to achieve a vertical rms deviation not exceeding 50 μm all along the fast energy ramp. In the near future we plan to accelerate polarized electrons up to 3.2 GeV. Therefore, both the power supplies and the corrector magnets have been currently upgraded: first, new power supplies working with a pulsed transistor H-Bridge were developed and successfully installed. Additionally, the existing vertical corrector magnets will now be replaced by newly developed ones. In our contribution, we will present the new correction hardware supplemented by the beam position monitors and their readout electronics. | ||
| MOPME007 | High Resolution Synchrotron Light Analysis at ELSA | 482 |
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Funding: Funded by the DFG within the SFB/ TR 16 The Electron Stretcher Facility ELSA provides polarized electrons with energies up to 3.5 GeV for external hadron experiments. In order to suffice the need of stored beam intensities towards 200 mA, advanced beam instability studies need to be carried out. An external diagnostic beamline for synchrotron light analysis has been set up and provides the space for multiple diagnostic tools including a streak camera with time resolution of < 1 ps. Beam profile measurements are expected to identify instabilities and reveal their thresholds. The effect of adequate countermeasures is subject to analysis. The current status of the beamline development will be presented. |
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| MOPME008 | Beam Diagnostics by Using Bunch-by-bunch Feedback Systems at the DELTA Storage Ring | 485 |
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Funding: Work supported by BMBF (05K10PEB) At DELTA, a 1.5-GeV electron storage ring operated by the TU Dortmund University, longitudinal and transverse bunch-by-bunch feedback systems are in use to detect and suppress multi-bunch instabilities. Besides that, the digital feedback systems are excellent diagnostics tools. As an example, by exciting a certain number of bunches within the bunch train, the coupling to the non-excited bunches can be investigated below and above the instability threshold. Other examples include studies of the injection process and monitoring bunch oscillations during sudden beam loss. First experimental results will be presented in this paper. |
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| MOPME010 | Transverse Beam Profile Diagnostics using Point Spread Function Dominated Imaging with Dedicated De-focusing | 488 |
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| Transverse beam profile diagnostics in electron accelerators is usually based on direct imaging of a beam spot via optical radiation (transition or synchrotron radiation). In this case the fundamental resolution limit is determined by radiation diffraction in the optical system. A method to achieve resolutions beyond the diffraction limit is to perform point spread function (PSF) dominated imaging, i.e. the recorded image is dominated by the resolution function of a point source (single electron), and with knowledge of the PSF the true image (beam spot) may be reconstructed. To overcome the limited dynamical range of PSF dominated imaging, a dedicated de-focusing of the optical system can be introduced. In order to verify the applicability of this method, a proof-of-principle experiment has been performed at the Mainz Microtron MAMI (University of Mainz, Germany) using optical transition radiation. Status and results of this experiment will be presented. | ||
| MOPME011 | Investigation of the Applicability of Parametric X-ray Radiation for Transverse Beam Profile Diagnostics | 491 |
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Transverse beam profile diagnostics in electron linacs is widely based on optical transition radiation (OTR) as standard technique which is observed in backward direction when a charged particle beam crosses the boundary between two media with different dielectric properties. The experience from modern linac based light sources like LCLS or FLASH shows that OTR diagnostics might fail because of coherence effects in the OTR emission process. A possibility to overcome this limitation is to measure at much shorter wavelengths, i.e. in the X-ray region, using parametric X-ray radiation (PXR) which additionally offers the advantage to be generated at crystal planes oriented under a certain angle to the crystal surface, thus allowing a spatial separation from a possible COTR background *. A first test experiment has been performed at the Mainz Microtron MAMI (University of Mainz, Germany) in order to study the applicability of PXR for beam diagnostics, and the status of this experiment will be presented.
* A. Gogolev, A. Potylitsyn, G. Kube, Journal of Physics 357 (2012) 012018 |
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| MOPME012 | Single-bunch Longitudinal Phase Space Diagnostics in Multi-bunch Mode at the European XFEL | 494 |
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| Dedicated longitudinal electron beam diagnostics is highly demanded for the control and optimization of modern X-ray free-electron lasers (XFEL). At the European XFEL, 3 transverse deflecting structures (TDS) will be installed at different locations of the accelerator for measurements of slice emittance and longitudinal profile. Operation of a TDS in combined use with an energy spectrometer, e.g. a dispersive section after a single dipole magnet, allows additionally for longitudinal phase space (LPS) measurements. However, utilization of a dipole magnet is not compatible with single-bunch measurements in multi-bunch operation mode, which will be the standard operation mode of the European XFEL. In this paper, we propose a LPS diagnostic beamline consisting of a TDS, fast kicker and septum magnet for the European XFEL. The layout of the accelerator lattice with optimized optics for LPS measurements will be presented. | ||
| MOPME013 | 20 Years of Development of SQUID-based Cryogenic Current Comparator for Beam Diagnostics | 497 |
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| This contribution gives an overview on the development of highly sensitive SQUID-based Cryogenic Current Comparators (CCC) for nuclear physics from the first successful demonstration of its performance at GSI Darmstadt through the latest improved version for FAIR and the Cryogenic Storage Ring at MPI Heidelberg. An absolute and exact measurement of the intensity of charged particle beams - extracted from an accelerator or circulating in a Storage Ring - is one of the major problems of beam diagnosis. Also the measurement of so-called dark currents, generated by super-conductive RF accelerator cavities at high voltage gradients to characterize the quality of these components becomes more and more important for the commissioning of new accelerators (XFEL at DESY). The Cryogenic Current Comparator (CCC) based on high precision LTS SQUIDs is an excellent tool to solve these problems. | ||
| MOPME014 | Electro-optical Bunch Length Measurements at the ANKA Storage Ring | 500 |
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Funding: Supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320 and by the German Federal Ministry of Education and Research under contract number 05K10VKC A setup for near-field electro-optical bunch length measurements has recently been installed into the UHV system of the ANKA storage ring. For electro-optical bunch length measurements during ANKA's low alpha operation, a laser pulse is used to probe the field induced birefringence in an electro-optical crystal (GaP in our case). The setup allows for both electro-optical sampling (EOS, multi-shot) and spectral decoding (EOSD, single- and multi-shot) measurements. This paper presents first results and discusses challenges of this method employed for the first time at a storage ring. |
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| MOPME015 | Numerical Wakefield Calculations for Electro-optical Measurements | 503 |
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Funding: This project is funded by the Federal Ministry of Education and Research under the contract number 05K10VKC The technique of electro-optical measurements allows precise and single-shot measurements of the bunch length and shape. The installation of such a near-field setup changes the impedance of the storage ring and the corresponding effects have to be studied carefully. One possibility is to use numerical codes for simulating the wakefields induced by the setup. Such simulations has been done using the wakefield solver implemented in the CST Studio Suite. In this paper we present the simulation results together with first measurements. |
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| MOPME018 | BEAM OSCILLATION MONITOR FOR THE MULTI-BUNCH BEAM | 506 |
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| In order to observe the motion of bunch-by-bunch beam oscillation of multi-bunch in the storage ring, we developed two measurement tools. One is a signal process electronics circuit using fast analogue switches. The circuit picks up one of the selected bunch signal of the beam position monitor from the multi-bunch. The selected beam position signal can be processed as a single bunch beam. By changing the gate timing, arbitrary bunch signal can be selected. The other is a waveform memory using a high bandwidth oscilloscope. The long waveform memory of the oscilloscope has a capability to acquire the multi-turn waveform of the button electrode signals. The beam test of the circuit has been carried out at KEK-ATF damping ring in the cases of 2.8ns bunch spacing and 5.6ns bunch spacing, respectively. The detail of the hardware and the result of the beam test are reported. | ||
| MOPME019 | Alignment Detection Study using Beam Induced HOM at STF | 509 |
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| STF accelerator using L-band photocathode RF Gun and two superconducting cavities is under operation for R&D of ILC. Electron beam extracted from the RF Gun is accelerated to 40 MeV by two superconducting cavities. Cavity alignment requirements for ILC are less than 300um offset and 300urad tilt with respect to cryomodule. It is necessary to measure their offset and tilt inside of cryomodule. Cavity offset has been already measured by using beam induced HOM at FLASH in DESY. Cavity deformation during assembly and by cooling contraction has not been examined yet. We measured HOM signals to detect their tilt and bending. TE111-6 which has high impedance is used to estimate cavity offset. To find cavity tilt and bending, we selected pi over nine mode in the first dipole passband (TE111-1) and beam pipe modes. From information of TE111-1 which has maximum radial electric field in the middle cell, we can get electrical center of middle cell. At beam pipes, electrical center can be found by using beam pipe modes. Combinations of these electrical centers tell us cavity tilt and bending. We will present results of these TE111-1 and beam pipe mode together with beam trajectory information. | ||
| MOPME020 | Development of the New Measurement Method for the Incoherent Tune Spread and the Tune Shift Caused by the Space Charge Effect | 512 |
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| For the high intensity accelerator, the incoherent tune which is the frequency of the individual particles is shifted and decreases due to the space charge effect. In addition, the incoherent tune is formed into spread shape commonly. When the incoherent tune satisfies a resonance condition, it might be occurred the beam emittance growth and the beam loss. So it is necessary to reduce the incoherent tune spread and the tune shift as much as possible. To achieve this condition, it is desired to measure the incoherent tune spread and the tune shift directly. Therefore we are developing the new measurement method of the incoherent tune spread and the shift due to the space charge effect. From the simulation results, it was cleared that the beam distribution can be modified in the case of using the mono frequency dipole exciter because a particle which has the tune corresponding to the exciter can be resonated temporary. In addition, it was cleared that it is possible to evaluate the incoherent tune spread and the tune shift by the measurement of the distribution transition. We present the outline of this method and the developing plane at the J-PARC RCS. | ||
| MOPME021 | Ionization Profile Monitor (IPM) of J-PARC 3-GeV RCS | 515 |
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| Ionization profile monitors (IPM) were installed in the 3-GeV RCS ring of J-PARC and used to observe the beam-profile for the transverse plane in beam commissioning. These electrodes and MCPs of IPMs were upgraded in 2012 summer shutdown in order to improve the external electric field for leading the electrons and ions to MCPs. This presentation will be described the results of observed beam profile in beam commissioning and be discussed the new issues for the ion and electron collection mode. | ||
| MOPME022 | Beam Commissioning of Two Horizontal Pulse Steering Magnets for Changing Injection Painting Area from MLF to MR in the 3-GeV RCS of J-PARC | 518 |
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| We have been successfully commissioned two pulse steering magnets installed in the Linac to 3-GeV RCS (Rapid Cycling Synchrotron) injection beam transport (BT) line of J-PARC. RCS has to deliver a simultaneous as well as specific beam as demand by the downstream facilities of MLF (Material and Life Science Facility) and the MR (Main Ring). In order to obtain relatively a smaller transverse emittance at extraction, those magnets were designed to perform a smaller injection painting for the MR beam as compared to the MLF one. As stripper foil position is fixed for the charge exchange H− injection, inclination of the injected beam centroid on foil for the MR beam is only moved to a smaller value by the pulse steering magnets, while DC septum magnets are fixed as determined first for the MLF beam. Their parameters were found to be very consistent with expectation and thus already in operation for switching to a painting area of 100 pi mm mrad for the MR beam as compared to that of 150 pi mm mrad for the MLF beam. | ||
| MOPME023 | ORBIT Beam Simulation Progress in the 3-GeV Rapid Cycling Synchrotron of J-PARC | 521 |
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| We have made a numerous progress for beam simulation in the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) by using 3-D particle tracking code, ORBIT. Namely, the TEAPOT lattice file used for ORBIT tracking has been made to give exactly same results to that with SAD model used for the RCS beam commissioning. In addition, time dependent lattice functions of the injection chicane magnets and similar other time dependent lattice imperfections, which are already found to have significant influences on the beam losses in the real machine have also been successfully introduced. At present, time dependent transverse and longitudinal impedances are going to be introduced. That should prove the ORBIT code much more matured for beam simulations in synchrotrons. Latest beam simulation results illustrating these new realistic features are presented. | ||
| MOPME024 | Status of Beam Loss Spatial Distribution Measurements at J-PARC Linac | 524 |
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Funding: This work was supported by JSPS KAKENHI Grant Number 24510134. We have developed 8-plane (4 horizontal and 4 vertical) scintillating fiber hodoscope system to measure proton tracks due to beam loss in the ACS section at the J-PARC linac. The detector consists of upstream 4 planes (two horizontal and two vertical) and downstream 4 planes (two horizontal and 4 vertical). The time of flight measuremments between the upstream and downstream subsystems allow proton identification and energy mesurements. In summer of 2012, we have installed remote position movement system, which enables measurements of spatial distributions of proton tracks. In this presentation we show status of mesurements and data analysis. |
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| MOPME025 | Production of Extraction Kicker Magnet of the J-PARC 3-GeV RCS | 526 |
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| The J-PARC 3-GeV rapid cycling synchrotron (RCS) has been provided proton beam to the Material and Life Science Facility (MLF)as well as to the 50 GeV Main Ring (MR). Proton beam is accelerated from 181 MeV to 3GeV in the RCS and immediately extracted it to the beam transport line to the MLF and the MR. Extraction kicker magnets are used for this fast extraction. To improve reliability of the RCS for user operation, production of a reserve kicker magnet has been performed. The kicker magnet mainly consists of Ni-Zn ferrite cores and Aluminum alloy plates, and these parts are installed in vacuum chamber to prevent discharge because a high voltage is applied to the magnet for a short period. Since it is important to reduce the outgassing of water vapor form these parts to prevent discharge, we has been produced the reserve magnet with low outgassing at high voltage discharge. Since assemble of the kicker magnet already finished and vacuum test has been performed, the result of vacuum test is reported. | ||
| MOPME026 | Beam Monitor Layout for Future ACS Section in J-PARC Linac | 529 |
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| In J-PARC Linac, an energy and intensity upgrade project has started since 2009 using Annular Coupled Structure (ACS) cavities. With this upgrade, the design peak current will be increased from the present 30 mA to 50 mA, and the energy from 181 MeV to 400 MeV. Along with these significant upgrades of the beam parameters, beam monitors should be followed. Also, the bunch shape monitor and new beam loss monitoring system will be employed for the new beam line. Newly fabricated devices will be delivered in the ACS beam line. And beam monitor layout of the upstream and downstream of ACS beam line will be modified. In this paper, we introduce the development of the beam diagnostic devices for the project and the new designed beam monitor layout. | ||
| MOPME027 | Bunch Length Measurement of 181 MeV Beam in J-PARC Linac | 532 |
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| In J-PARC Linac, an energy and intensity upgrade project has started since 2009 using Annular Coupled Structure (ACS) cavities. Because the longitudinal matching before ACS cavities is additionally required, we decided to employ the bunch shape monitors (BSMs) to measure the longitudinal beam profile. After three years from the start of BSM project, three BSMs were fabricated. All three BSMs were installed during the summer shutdown of 2012. We tried to measure the longitudinal beam profile exited from SDTL cavities. In this paper, we introduce the outline of BSM project, the first data acquisition and related small problems. | ||
| MOPME028 | A Preliminary Study of the Vibration Wire Monitor for Beam Halo Diagnostic in J-PARC L3BT | 535 |
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| In the J-PARC 3-GeV Rapid Cycle Synchrotron (RCS), transverse beam halo diagnostic and scraping are required to increase the output beam power. Wire scanners and halo scrapers were used for measurement of projected beam distributions to determine the extent of beam halo formation at Linac-3GeV Beam Transport line (L3BT). In order to determine more detail of halo formation, Vibration Wire Monitor (VWM) was installed in L3BT for the beam halo measurement and the offline study at the test stand with low energy electron gun are started. The high sensitivity of the VWM makes it a prospective one for investigation of beam halo and weak beam scanning. In this paper, we will report a preliminary results of offline studies and beam halo measurement by VWM at L3BT. | ||
| MOPME029 | Multi-strip Current Monitor for Pulsed Laser Plasma Diagnostics | 538 |
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| A compact position-sensitive beam instrumentation devise is under development. The beam detection area of this devise is composed of multi-strip electrodes and scanned by multiplexers, which reduces the number of read-out lines and feed-through connectors. Combined with an electrostatic deflector and ToF information, this monitor can discriminate charge to mass ratios of particles. A prototype of this monitor is fabricated for measurement of ion distribution and charge state in laser induced plasma. This model has fifteen strip electrodes and the multiplexed signal and the clock signal are read out through two coaxial cables. Thus, only three cables are needed including a +5V power supply line. The test result will be presented. | ||
| MOPME031 | Emittance Measurement with Multi-wire Scanners for BEPC-II Linac | 541 |
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| During the BEPC-II linac upgrade, five wire scanners have been installed in the common transport line, which makes a fast emittance measurement possible. In this paper, we will show the primary results of BEPC-II linac emittance measurement using multi-wire scanner method. The least squares method will be used for data analysis. A comparison of the results with the ones obtained by quad scan method will also be given. | ||
| MOPME033 | Wire Scanner Emittance Measurement and Software Design at BEPCII | 544 |
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| Wire scanners are diagnostic devices to measure the beam profile. Resent years, BEPCII adopts wire scanner measurement system for accurate beam size and emittance measurements. Beam emittance measurements can be performed with no adverse impact on beam and no interruption to normal machine operation. The BEPCII wire scanner system includes sets of four scanners in linac by which the linac output emittance is determined. In order to make the measurement procedure automated and easily accessible to all operators, wire scanner measurement software is developed. The software can obtain real-time signal data from the Experimental Physics and Industrial Control System(EPICS) and emittance calculation, phase chart and optics envelope display will be done. In this paper we describe the construction, performance and uses of BEPCII wire scanners measurement system and software. | ||
| MOPME035 | Design of a Non-Intercepting Beam Diagnostic Device Using Neutral Beam Fluorescence Method | 547 |
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| The forward neutral beam from deflecting magntic field carries some characteristic properties of high intensity particle beams, such as profile, emittance etc. Therefore a reliable measurement of neutral beam fluorescence can be used to develop a fast and non-interceptive beam diagnostic tool. A non-intercepting beam emittance (profile) monitor using neutral beam fluorescence method has being constructed at Peking University. As a performance test, an emttiance of an extracted proton beam from a permanent magnetic electron cyclotron resonance (ECR) ion source was successfully measured. The details of design and results of measurement will be presented in this paper. | ||
| MOPME036 | Prototype Experiment Preparation of a 54.167MHz Laser Wire System for FEL-THz Facility at CAEP | 550 |
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| In this paper, a prototype experiment preparation of a 54.167 MHz laser wire system is presented, which will be used to measure the beam size of a CW DC gun built as an electron source of FEL-THz facility in China Academmy of Engineering Physics (CAEP). The rms beam size is less than 1 mm and the average current of the electron beam is more than 1 mA. This new-type LW system ultilizes the excess power other the photocathode drive laser and becomes much cheaper and simpler. Plus, it can distinguish beams with different energies which are very close in ERLs. The system layout and the simulation results are also presented. | ||
| MOPME038 | A New Theoretical Design of BLM System for HLS II | 553 |
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| Beam loss monitoring (BLM) system has been commonly used to detect the vacuum leakage. The existing BLM system for Hefei Light Source (HLS) was built in 2000. It played an important role in analyzing beam loss distribution and regulating the machine operation parameters. Recently, HLS is being upgraded to HLS II. The emittance will be decreased to increase the brilliance of synchrotron radiation. The Touschek lifetime will be much shorter than before, and dominate the total beam lifetime. It is necessary to redesign the BLM system for HLS II. The most important part of this work is to find a better method of monitoring Touschek lifetime by BLM system while keeping its general functions. According to the results of our research, a preliminary theoretical design for the new BLM system is proposed in this paper. This new system will play an important role in the storage ring commissioning, troubleshooting, and beam lifetime studying. | ||
| MOPME039 | A New Method of Acquiring Fast Beam Transversal Profile in the Storage Ring | 556 |
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| A new method of acquiring fast beam transverse profile has been developed and will be used in HLS II. This method is based on four signals from MAPMT (multi-anode photo-multiplier tube) and logarithm processing technique. First, the calculation formula of beam transversal size and position are deduced using above method. Then, the main performances (e.g. sensitivity and linearity range) are analyzed. According to stimulation result, regardless of cross-talk and inconsistency between channels, the size signal has a linear relation with size s when s=0.8-2mm and position d=±2mm, the position signal has a linear relation with position d and the linear range exceeds ±2mm when s=0.8-2mm. With channel cross-talk and channel inconsistency being considered, the stimulation results also are given. Finally, a fast beam transverse profile monitor is designed and provides turn-by-turn measurement of the beam transverse profile. | ||
| MOPME040 | Cavity-based Multi-parameter Beam Diagnostics at HLS | 559 |
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Funding: Natural Science Foundation of China (11005106) Recent developments of the fourth generation light sources needs precious control of beam parameters, such as beam position, transverse emittance, beam density, bunch length, etc.. Non-destructive on-line beam diagnostic methods are then required. As an example, the cavity beam multi-parameter monitor system designed for the HLS photocathode RF electron gun consists of a beam position monitor, a beam quadrupole moment monitor and a beam density and bunch length monitor. The cavity beam position monitor uses a re-entrant position cavity tuned to TM110 mode as position cavity and cut-through waveguides to suppress the monopole signal. Beam quadrupole moment monitor system consists of a square pill-box quadrupole moment cavity, a cylindrical pill-box reference cavity and a waveguide coupling network. TM0n0 modes of cavity can be used to work out beam density and bunch length simultaneously. To simplify the design and suppress the whole system here, we use the reference cavity of beam position monitor as beam density and bunch length signal pick-up. |
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| MOPME041 | Design and Calculation of the Stripline Beam Position Monitor for HLS II Storage Ring | 562 |
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Funding: Supported by the National Science Foundation of China (10875117, 11005105, 11175173) According to the requirements of HLS II upgraded, in order to acquire the non-intercepting measurement of beam position and quadrupole component, a new stripline beam position monitor (BPM) was designed for storage ring. The BPM parameters were optimized to acquire impedence matching with characteristic impedance of the external transmission lines and the coupling coefficients between the electrodes were calculated. According to the difference/sum and log-ratio methods, the horizontal and vertical sensitivities, mapping figures and fitting polynomials wered acquired. The results showed that sensitivities using log-ratio method were bigger than those using difference/sum method. The sum signal was also simulated when beam displacement varied from (0 mm, 0 mm) to (5 mm, 5 mm), the result showed that the variation of normalized sum signal was no more than ±6%. The gaussian weighted method of a two-dimensional grid structure was used to simulate the gaussian bunch and simulate the beam transverse quadrupole component changing with position (x, y), the result showed that the beam transverse quadrupole component changed linearly with position combination (x2-y2). |
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| MOPME042 | A PRELIMINARY SIMULATION OF BPM SIGNAL DIODE DETECTOR FOR HLS II TUNE MEASUREMENT SYSTEM* | 565 |
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Funding: Supported by National Natural Science Foundation of China (11105141, 11175173) and the Fundamental Research Funds for the Central Universities (WK2310000015) A high sensitivity BPM signal detection front-end electronics has been designed for HLS II tune measurement system according to the HLS II upgrade requirements. Classical tune measurement systems filter out just one or a few of these betatron sidebands frequency. As a consequence, most of the betatron energy is dropped and only a very small energy remains for further processing. A new method, referred to as Direct Diode Detection (3D) by LHC[1], improves the situation. In this paper, the HLS II BPM signals have been calculated out in time domain and frequency domain. Basing on the characteristics of HLS II BPM signal, a preliminary simulation is performed to test and verify the feasibility of diode detector for HLS II tune measurement system. The simulation results clearly show that the technique of diode-based circuit can be applied to HLS II tune measurement. |
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| MOPME043 | Calibration of Beam Position Monitors in the Injector of HLS II | 568 |
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Funding: Supported by the National Science Foundation of China (11175173, 11105141) A beam position monitor(BPM) system is being installed to improve the beam position measurement of the injector at the upgrade project of Hefei Light Source (HLS II). The new BPM system is consists of 19 stripline BPMs and 19 Libera Brilliance Single Pass modules. Before installation, the response of the BPMs must be mapped to improve the accuracy of measurement. The theoretical equations of both position and quadrupole component of the BPM are calculated first, using both formula and matlab simulation. A laboratory calibration system is built. The inconsistency of Libera Brilliance Single Pass channels is measured to improve the accuracy of calibration. The calibrating results show the position sensitivity is less than 5% difference compare to the theoretical value, while the quadrupole component sensitivity is less than 10% difference. |
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| MOPME044 | A Novel Type of Forward Coupler Slotted Stripline Pickup Electrode for CSRe Stochastic Cooling | 571 |
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| A novel type of slotted or perforated strip-line pick-up or kicker electrode structure for CSRe stochastic cooling for non relativistic particle beams with b=v/c values around 0.7 is presented. This slotted structure is to be used as a forward coupler with the output signal taken from the downstream end and has a rather large relative bandwidth of several octaves. The electrode structure and pickup tank, as well as the beam test result will be presented in this paper. | ||
| MOPME045 | Design and Test Status of Beam Position Monitors for ADS Injector II Proton LINAC | 574 |
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| Beam Position Monitors (BPM) based on capacitive pick-ups are designed for Accelerator-Driven System (ADS) Injector II proton LINAC. This LINAC is aiming to produce a maximum design current of 15 mA at the 10 MeV energy with an operating frequency of 162.5 MHz. Non-interceptive BPM will be installed to measure the transverse beam position and beam phase in the vacuum chamber. Depending on the location, the response of the BPMs must be optimized for a beam with an energy range from 2.1 up to 10 MeV and an average current between 0.01 and 15 mA. Apart from the broadening of the electromagnetic field due to the low-beta beam, specific issues are affecting some of the BPMs: tiny space in the transport line between the RFQ and the cryomodule and the cryogenic temperature inside the cryomodule. For this reason two types of BPMs are being designed for each location (MEBT and cryomoudle). In this contribution, the present status of the design and measured results for each BPM will be presented in room and cold temperature, focusing on the electromagnetic response for low-beta beams. | ||
| MOPME046 | Preliminary Experimental Results of Axial B-dot Measuring Beam Tilt | 577 |
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Funding: This work is under the support of NSFC project No. 11175166 Beam monitors sensitive to the beam's azimuthal B-dot field (sometimes referred as B-dots) are widly used to measure the displacement of beam centroid, as the beam generates a dipole term of the azimuthal magnetic field. The authors have pointd out that the similar B-dots sensitive to axial magnetic field can be used to measure the beam tilt directly in earlier work. A monitor which consists of four azimuthal B-dots and four axial B-dos is designed and fabricated. The monitor was tested on a coaxial calibration stand, which has a character resistance of 50 Ohm. Two position tuners are installed on the calibration stand, to adjust the position and the tilt of the inner conductor. Experiments show that the axial B-dot monitor can be successfully used to measure the tilt of the inner conductor directly. |
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| MOPME047 | Simulation of a Beam Angel Monitor using the Axial B-dot Field | 580 |
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Funding: The National Natural Science Foundation of China A beam angel monitor using the axial B-dot field was presented recently while the one using azimuthal B-dot field had been widely employed to measure the beam positions for more than ten years. Basing on the principle of the proportionality between the deflection angel and the difference of axial B field with corresponding positions, the axial B-dot monitor has a potential use for beam deflection angle measurement directly. A test stand was built to test and improve the axial B-dot monitor, which is fabricated as a PCB structure. Meanwhile, simulations using the CST MWS code have been performed, demonstrating a good agreement to the test results and giving some advice to suppress the disturbance of position deviation of the beam. |
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| MOPME049 | Status of Non-destructive Bunch Length Measurement based on Coherent Cherenkov Radiation | 583 |
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Funding: This work was supported by the joint Russian-Chinese grant (RFBR 110291177 and NSFC 11111120065) and partially by the Program of Russian MES “Nauka” and the Chinese NSFC 11175240. As a novel non-destructive bunch length diagnostic of the electron beam, an experimental observation of the coherent Cherenkov radiation generated from a dielectric caesium iodide crystal with large spectral dispersion was proposed for the 30MeV femtosecond linear accelerator at Shanghai Institute of Applied Physics (SINAP). In this paper, the theoretical design, the experimental setup, the terahertz optics, the first angular distribution observations of the coherent Cherenkov radiation, and the future plans are presented. * Shevelev M. et al., Journal of Physics: Conf. Ser. 357 (2012) 012023. |
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| MOPME051 | Development of Cavity Beam Position Monitor System | 586 |
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| Shanghai soft X-ray free electron laser (SXFEL) facility requires beam position resolution better than 1 μm in the undulator sections. Cavity BPM system, feasible in obtaining sub micron position resolution, has been developed to achieve the goal. Two cavity prototypes with high Q and low Q were designed and fabricated. The relevant dedicated electronic, which could cover the two types of cavity BPMs, also have been developed. Fast fourier transform (FFT) and digital down converted based algorithms were implemented. The beam test of the whole system has been scheduled on the Shanghai deep ultraviolet (SDUV) FEL facility. The cavity design, electronic architecture, achieved performance during beam test will be presented. | ||
| MOPME052 | Beam Instrumentation System Optimization for Top-up Operation in SSRF | 589 |
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| In order to offer higher average brightness and more stable photon beam, top-up injection mode is scheduled for daily operation in SSRF. Several critical beam parameters, such as fill pattern, average current, beam lifetime and transfer efficiency, need to be measured precisely and reliably, and few interlock logics need to be added into machine protection system with top-up mode. Hardware and software optimizations of beam instrumentation for this purpose will be introduced in this paper. | ||
| MOPME053 | Point Spread Function Study of X-ray Pinhole Camera in SSRF | 592 |
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Funding: Supported by National Natural Science Foundation of China (11075198) An X-ray Pinhole Camera that has been used to present the transverse beam size with an intuitive grasp of the distribution of the beam radiation was installed on one beam-line of the storage ring in Shanghai Synchrotron Radiation Facility (SSRF). The real beam size however is a function of the image size of the CCD camera and the point spread function (PSF) of the system. The PSF was calculated but poorly tested. This article will present the measurement of the PSF with a series of beam based experiments and the consistency with the theoretical beam size. |
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| MOPME054 | Bunch-by-bunch Beam Position and Charge Monitor based on Broadband Scope in SSRF | 595 |
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| A bunch-by-bunch beam position and charge monitor system, based on a broadband oscilloscope, has been developed at SSRF. The beam positions of each bunch could be located independently in this system by using the original signals from the button-type pickups on the storage ring. The relative charge of each bunch could be obtained by the sum signal from the pickups. Using sum weighted average method, turn-by-turn beam position could be got from the bunch-by-bunch beam position data. The difference of each bunch beam position have been observed during injection at SSRF. | ||
| MOPME056 | Measurement of the Beam Position Monitor’s Electrical Performance and Electronics Sensitivity for 100 MeV Proton Linac and Beam Lines | 598 |
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Funding: This work was supported by the Ministry of Education, Science and Technology of the Korean Government. The development of the beam position monitor (BPM) is in progress for the 100-MeV proton linac and 10 beam lines of the 1st phase of KOMAC. Those were selected the strip line type BPM for the proton linac and beam lines. 5 beam-line BPMs and 9 linac BPMs were checked their electrical performance in the RF test using by developed test stand and tested the Log-ratio BPM (Beam Position Monitor) electronics module of the Bergoz Instrumentation for direct beam position derivation signal from the pickup signal. After then, those will be installed 100-MeV proton Linac and beam lines for beam commissioning in February 2013. This presentation summarized the results of measured BPM’s electrical performance and the Log-ratio BPM electronics pickup sensitivity. |
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| MOPME057 | Preliminary Operation of the Beam Loss Monitoring System at the 100-MeV Proton Linac | 601 |
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A 100-MeV proton linac has been developed as the 1st phase of KOMAC (Korea Multi-purpose Accelerator Complex) under the project name of PEFP (Proton Engineering Frontier Project). The accelerator operation has to be carried out with the objective of limiting beam losses to less than 1 W/m. When the un-intended excessive beam loss occur, the BLM(Beam Loss Monitor) inform this beam loss to operator and transmit the signal to the MPS (Machine Protection System) for the rapid shut-off of the machine. The scintillation detector and proportional counter were selected as the BLM detector because of their fast response time and high sensitivity. At the beam commissioning stage, 20 BLMs will be prepared for the beam loss monitoring. This paper will report preliminary operation results of beam loss monitoring system.
This work was supported by the Ministry of Education, Science and Technology of the Korean Government. |
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| MOPME058 | DEVELOPMENT OF A CAVITY-TYPE BEAM POSITION MONITORS WITH HIGH RESOLUTION FOR ATF2 | 604 |
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| We have developed a high resolution beam position monitors for ATF2 at KEK, which is an accelerator test facility for International Linear Collider(ILC). The main goals of ATF2 are achievement of 37nm beam size and 2nm beam position resolution for beam stabilization. For these goals, low-Q IP-BPM(Interaction Point Beam Position Monitor) with latency of 20 ns are being developed. In this paper, we will describe about design of Low-Q IP-BPM, the basics test results as RF test and BPM sensitivity test. Electronics for Low-Q IP-BPM will be also described. | ||
| MOPME059 | R&D of a Beam Position Monitor for RISP | 607 |
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| We have investigated on the R&D of stripline beam position monitor for the heavy-ion accelearator at Korea. We present the detailed design and fabrications on the beam position monitor in superconducting linac that the beam is accelerated to 200 MeV/u. | ||
| MOPME060 | Introduction to Beam Diagnostics Components for PAL-ITF | 610 |
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| Pohang Accelerator Laboratory (PAL) is building the 4th generation X-ray free electron laser (XFEL). The Injection Test Facility (ITF) is a test facility established to improve the functions of the laser gun and pre-injector to be installed in XFEL. To improve the effects of ITF, two factors are required. The first is to be able to generate low-emittance electron beams stably at the laser gun, and the second is to control increasing emittance by space charge effect by accelerating electron beams with high energy at the pre-injector. In this way, high-quality electron beams can be materialized. Various beam diagnostics are installed in the accelerator system for beam diagnostics and measurements. Five kinds of beam diagnostics were installed in the PAL-ITF. These are (1) ICT and (2) Faraday Cup to measure current and electrons charge, (3) Stripline BPM to measure the location of beams, (4) a YAG/OTR Screen Monitor to measure beam energy and transverse profile motion and (5) a Wire Scanner to measure beam size. In this paper, the purposes and properties of each diagnostic unit and measurement results are introduced. | ||
| MOPME061 | Femtosecond e-bunch Length Measurement at fs-THz Accelerator at PAL | 613 |
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| Longitudinal distribution of femto-second electron beam has been evaluated by the coherent transition radiation Michelson interferometer with the reconstruction procedure from interferograms. We measure the bunch length of the Thz Accelerator using interferogram method in Pohang Accelerator Lab and compare with the energy of transition radiation and bunch length. | ||
| MOPME062 | UV and X-ray Diffraction Radiation for Submicron Noninvasive Diagnostics | 616 |
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Funding: This work was partially supported by Russian Ministry of Education and Science (State contract 12.527.12.5002). Diffraction radiation (DR) arises when a charged particle moves near a target. The theory of X-ray DR from single particles was created in [*, **], and recently the theory has been developed for bunches [***]. DR from relativistic particles is used for noninvasive bunch diagnostics and also for creating new and effective sources of radiation, including Free-electron laser based on the Smith-Purcell effect. In the present work we explore theoretically DR from the bunch of ultrarelativistic charged particles at X-ray and UV frequencies domains. It is shown that incoherent part of form-factor, describing the effect of N electrons in bunch, exists and differs from the unity. The coherent part of radiation depends on transversal size of the bunch as ratio of the Bessel function to its argument. The coherence effects are proved to be important up to the wavelengths much less than transversal size of the bunch. The results obtained open the possibility to diagnose bunches of the submicron size with very high accuracy. * A.A. Tishchenko et al, PLA. 359 (2006) 509. ** A.P. Potylitsyn et al, Diffraction radiation from relativistic particles, Springer, 2010 *** D.Yu. Sergeeva et al, Proc. Channeling-2012, p.52, 2012 |
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| MOPME063 | Backward X-ray Transition Radiation from Multilayered Target for Submicron Beam Diagnostics | 619 |
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Funding: This work was partially supported by Russian Ministry of Education and Science (State contract 12.527.12.5002). Backward transition radiation (TR) is a TR arising in the direction of mirror reflection relative to the charged particles trajectory. Therefore for oblique incidence it can be emitted under big angles which is useful from point of view of measuring of the radiation. In spite of the fact that backward TR in X-ray frequency domain is much weaker than forward TR [*], it has recently been proposed by A.P. Potylitsyn and others [**] as an instrument for submicron electron beam diagnostics. In this work we propose to use the multilayered target in order to enhance the resulting radiation, i.e. to use resonant backward X-ray TR. So far X-ray TR has not been explored theoretically for backward geometry. It is shown that the expressions obtained coincide in special case of forward resonant X-ray TR with the results by L. Durand (***) and X. Artru (****). We explore the spectral and angular characteristics of resonant backward X-ray TR form point of view of submicron beam diagnostics for the ultrarelativistic charged particles bunches. The role of absorption in the target material and also the coherent and incoherent parts of the radiation is analyzed * A.A. Tishchenko et al, NIMB 227 (2005) 63. ** L.G. Sukhikh et al, J of Phys: Conf. Ser. 236 (2010) 012011. *** L. Durand, Phys Rev D11 (1975) 89. **** X. Artru et al, Phys Rev D12 (1975) 1289. |
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| MOPME064 | SLM and Flags for Booster of NSLS-II | 622 |
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| Set of diagnostics of booster of NSLS-II includes 6 fluorescent screens (flags) and 2 synchrotron light monitors (SLM). The flags will be applied during booster commissioning for closing of the beam turn. They are also a useful tool in case of malfunction elimination. SLM will be used both for booster comissioning and for operation. The details of calibration and design of the devices are discussed. | ||
| MOPME065 | Approximate Method of Calculation of a Bunch Radiation in Presence of Complex Dielectric Object | 625 |
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Funding: Work supported by the Grant of President of Russian Federation, Russian Foundation for Basic Research, and the Dmitry Zimin "Dynasty" Foundation. Cherenkov radiation is widely used for detection of charged particles and can be also applied for particle bunch diagnostics*. As a rule, dielectric objects applied for these goals have complex forms. Therefore development of methods of calculation of bunch radiation in presence of complex dielectric objects is now of a great interest. The approximate method developed by us allows to take into account influence of the object boundaries closed to the charge trajectory as well as "external" boundaries of the object. The case of the charge crossing a dielectric plate was considered as a test problem. The exact solution of this problem is in a good agreement with our approximate solution. Next, the cases of more complex objects were analyzed. One of them is a dielectric cone with a vacuum channel. Particularly, it was shown that radiation can be convergent under certain conditions, that is the field outside the cone can be more intensive than on the cone boundary. Radiation of the bunch in the case of dielectric prism was considered as well. * A.P. Potylitsyn, Yu.A. Popov, L.G. Sukhikh, G.A. Naumenko, M.V. Shevelev, Journal of Physics: Conference Series 236 (2010) 012025. |
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| MOPME066 | Radiation of a Charged Particle Bunch Moving along Boundary of Wire Metamaterial | 628 |
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Funding: Work supported by Russian Foundation for Basic Research and the Dmitry Zimin “Dynasty” Foundation. The material under consideration represents a periodical volume structure of long parallel conductive wires. If wavelengths are much greater than periods, the structure can be described as some anisotropic medium possessing both frequency and spatial dispersion* (so-called wire metamaterial). Earlier we considered the radiation of bunches moving in boundless wire metamaterial. It has been discovered that this radiation is nondivergent, and it is perspective for diagnostics of bunches**. Now we consider the case when the bunch moves in vacuum along the boundary of the semi-infinite metamaterial perpendicularly to the wires. Analytical and numerical analysis of the problem is performed. It is shown that radiation from a point charge concentrates in some vicinity of certain planes and propagates along the wires with speed of light. Series of computations show that the radiation under consideration can be useful for determination of sizes and shape of bunch. *A.V. Tyukhtin, E.G. Doilnitsina, J. Phys. D - Appl. Phys., 44, 265401 (2011). **V.V. Vorobev, A.V. Tyukhtin, Phys. Rev. Lett., 108, 184801 (2012). |
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| MOPME067 | Non-Invasive Bunch Length Diagnostics Based on Interferometry From Double Diffraction Radiation Target | 631 |
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Funding: This work was supported by the joint Russian-Chinese grant (RFBR 110291177 and NSFC 11111120065) and partially by the Program of Russian MES “Nauka” and the SINAP Xinrui Program Y15501A061. Reliable and precise non-invasive beam diagnostics technique to measure length of sub-picosecond electron bunches are required for new accelerator facilities (FEL, et al.). Investigations of coherent radiation generated by such bunches using different interferometers allow to determine a bunch length*. Measuring a dependence of radiation yield intensity from two DR targets on a distance between them (the intrinsic DR interferogram), it is possible to obtain the same information. Such a non-invasive technique can be directly used for ultra-short bunch length measurements. Recently the first experiment with a double DR target was carried out at the SINAP fs linac facility** with parameters described in***. The double DR target was consisted of two plates made from Al foil. The pyro-electric detector SPI-D-62 was used. Here we report the results of the second stage of our investigations. The DR interferograms of different electron bunch length were measured. The bunch length was reconstructed using the heuristic model based on the dimension theory and simulation data. We compare the results from DR interferograms and Michelson interferometer measurements and show their similarity. *Murokh A. et al., NIMA 410 (1998) 452. **Zhang J.B., Shkitov D.A. et al., IBIC’12 MOPB65 (2012). ***Lin X., Zhang J. et al., Chin. Phys. Let. V. 27 N. 4 (2010) 044101. |
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| MOPME068 | Feasibility Study of a 2nd Generation Smith-Purcell Radiation Monitor for the ESTB at SLAC | 634 |
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| The use of a radiative process such as the Coherent Smith-Purcell Radiation (CSPR) is a very promising non-invasive technique for the reconstruction of the time profile of relativistic electron bunches. Currently existing CSPR monitors do not have yet single-shot capability. Here we study the feasibility of using a CSPR based monitor for bunch length measurement at the End Station Test Beam (ESTB) at SLAC. The aim is to design a second-generation device with single-shot capability, and use it as a diagnostic tool at ESTB. Simulations of the spectral CSPR energy distribution and feasibility study have been performed for the optimization of the parameters and design of such a device. | ||
| MOPME069 | Multi-OTR System for Linear Colliders | 637 |
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| We study the feasibility of using a multi-Optical Transition Radiation (mOTR) system for fast transverse emittance reconstruction and x-y coupling correction in the Ring to Main Linac (RTML) of the future linear colliders: ILC and CLIC. OTR monitors are mature and reliable diagnostic tools that could be very suitable for the setup and tuning of the machine in single-bunch mode. Here we study the requirements for a mOTR system adapted to the optical conditions and beam parameters of the RTML of both the ILC and CLIC. | ||
| MOPME070 | Emittance and Beta Functions Measurements for the MAX IV Linac | 640 |
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| We plan to determine beam emittance and Twiss parameters for the MAX IV linac using multiple-quadrupoles scans. We investigate the possibility to perform such scans using matching sections' quadrupoles combined with beam profile measurements by fluorescent YAG screens. Beam pipe size, resolution and screen saturation limits and strengths of quadrupoles are taken into consideration. Our approach to this problem using Kalman filter is presented. | ||
| MOPME071 | Characterisation of Si Detectors for use at 2 Kelvin | 643 |
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Funding: This research project has been supported by a Marie Curie Early Initial Training Network Fellowship of the European Community’s Seventh Framework Programme under contract nr PITN-GA-2011-289485-OPAC. It is expected that the luminosity of the Large Hadron Collider (LHC) will be bounded in the future by the beam loss limits of the superconducting magnets. To protect the superconducting magnets of the high luminosity insertions an optimal detection of the energy deposition by the shower of beam particles is necessary. Therefore beam Loss Monitors (BLM) need to be placed close to the particle impact location in the cold mass of the magnets where they should operate in superfluid helium at 1.9 Kelvin. To choose optimal detectors n-type silicon wafers have been examined at superfluid helium temperature whilst under irradiation from a high intensity proton beam. The radiation hardness and leakage current of these detectors were found to be significantly improved at 1.9 Kelvin when compared to their operation at room temperature. |
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| MOPME072 | Performance Tests of a Short Faraday Cup Designed for HIE-ISOLDE | 646 |
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Funding: E.D.C, D.L. and A.S. acknowledge CATHI Marie Curie ITN: EU-FP7-PEOPLE-2010-ITN Project number 264330. M.A.F acknowledges co-funding by the European Commission (Grant agreement PCOFUND-GA-2010-267194) The On-Line Isotope Mass Separator (ISOLDE) facility at CERN is being upgraded in order to deliver higher energy and intensity radioactive beams. The final setup will consist in replacing the energy variable part of the normal conducting REX post-accelerator with superconducting cavities. In order to preserve the beam emittance, the drift space between the cryomodules housing these cavities has been kept to a minimum. As a consequence, the longitudinal space available for beam diagnostics is severely limited in the inter-cryomodule regions. A Faraday cup (FC) will be installed to measure beam currents, and due to the tight spatial constraints, its length is much smaller than usual. This poses a great challenge when trying to avoid the escape of ion-induced secondary electrons, which would falsify the current measurement. Two prototypes of such a short FC have therefore been tested at REX-ISOLDE using several beam intensities and energies, with the aim of determining its accuracy. In this paper the experimental results obtained for the two prototype cups are presented together with numerical calculations of the electrostatic fields that are produced inside the cup. |
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| MOPME073 | Measurement of Schottky-like Signals from Linac Bunched Hadron Beams for Momentum Spread Evaluation | 649 |
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| We present a novel method for the measurement of Linac beam parameters in the longitudinal phase space. The longitudinal momentum spread can be evaluated by means of Schottky type signal analysis of bunched beams. There is a close similarity between a repetitive Linac bunch train and a circulating beam with a single short batch in a large machine like the LHC. A dedicated longitudinal cavity pick-up was used in the Linac where resonance frequency and Q-value were carefully selected in order to get an optimum compromise between the unavoidable coherent signal and the desired incoherent part of the beam spectrum. A time domain gating similar to the 4.8 GHz LHC Schottky front-end is applied. As a cross-check of the validity of the interpretation in terms of momentum spread, the Linac beam is analyzed in the downstream synchrotron using standard Schottky methods. In principle, this approach can be understood as an extension of Schottky analysis for circular machines with a perfect “mixing” between subsequent bunch trains. This contribution describes the test set-up and discusses the results of the measurements with a heavy ion beam. | ||
| MOPME075 | Laser Based Stripping System for Measurement of the Transverse Emittance of H− Beams at the CERN LINAC4 | 652 |
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Funding: LA3NET is funded by the European Commission under Grant Agreement Number GA-ITN-2011-289191 The new LINAC4 at CERN will accelerate H− particles to 160 MeV and allow high brightness proton beam transfers to the Proton Synchrotron Booster, via a charge-exchange injection scheme. This paper describes the conceptual design of a laser system proposed for transverse profile and emittance measurements based on photon detachment of electrons from the H− ions. The binding energy of the outer electron is only 0.75 eV and can easily be stripped with a laser beam. Measuring the electron signal as function of the laser position allows the transverse beam profile to be reconstructed. A downstream dipole can also be used to separate the laser neutralized H0 atoms from the main H− beam. By imaging these H0 atoms as a function of laser position the transverse emittance can be reconstructed in the same way as in traditional slit-and-grid systems. By properly dimensioning the laser power and spot size, this method results in negligible beam losses and is therefore non-destructive. In addition, the absence of material intercepting the H− beam allows the measurement of a full power H− beam. This paper will focus on the general design and integration of both the laser and H0 detector systems. |
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| MOPME076 | Determination of Octupole and Sextupole Polarities in the LHC | 655 |
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| We report the results of measurements to verify the polarity of the LHC’s lattice focusing and defocusing octupoles (MOF and MOD), spool piece octupole correctors (MCO), arc skew sextupole correctors (MSS), and interaction region sextupoles (MCSX and MCSSX). Octupole polarities were determined by measuring the change to second order chromaticity when a magnet family was trimmed. The MSS skew sextupole corrector polarities were checked by measuring the change to chromatic coupling when a magnet family was trimmed. The polarities of the MCSSX skew sextupoles in IR 1 and the MCSX normal sextupoles in IR 5 were checked by measuring the tune shift due to a magnet trim. Comparison of measurements with model predictions indicates that the polarities of the octupoles and the IR sextupoles are correct, and the polarities of the MSS skew sextupole correctors are reversed. | ||
| MOPME077 | Electro-0ptical Bunch Profile Measurement at CTF3 | 658 |
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| A new electro-optic bunch profile monitor has recently been installed in CLIC Test Facility 3 at CERN. The monitor is based on an electro-optic spectral decoding scheme which reconstructs the longitudinal profile of the electron bunch by measuring its Coulomb field. The system uses a 780 nm fibre laser system, transported over a 20m long distance to the interaction chamber, where a ZnTe crystal is positioned close to the beam. The assembly also contains a traditional OTR screen, which is coupled to a second optical line and used to adjust the temporal overlap between the laser and the electron pulse. This paper presents the detection system in detail, as well as reporting on the first measurements performed with beam. | ||