Paper | Title | Other Keywords | Page |
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TUCL02 | Novel Accelerator Physics Measurements Enabled by NSLS-II RF BPM Receivers | impedance, vacuum, closed-orbit, feedback | 294 |
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NSLS-II light source has state of the art RF BPM receivers that were designed and built in-house incorporating the latest technology available in the RF, digital, and software domains. The recently added capability to resolve the orbits of multiple bunches within a turn as well as further improvement in transverse positional resolution for single- and few-bunch fills [*] allowed us to perform a number of novel beam dynamics measurements. These include measuring small impedances of vacuum chamber components, and of extremely small (~10-5) current-dependent tune shifts (transverse and synchrotron), as well as obtaining an amplitude-dependent tune shift curve from a single kicker pulse. We are also effectively utilizing our BPMs to decipher the lifetimes of individual bunches and to visualize single bunch instability dynamics. In this paper we review the unique capabilities of NSLS-II BPMs and present examples of beam physics measurements that greatly benefit from them.
* B. Podobedov, W. Cheng, K. Ha, Y. Hidaka, J. Mead, O. Singh, K. Vetter "Single Micron Single-Bunch Turn-by-Turn BPM Resolution Achieved at NSLS-II", in Proc. IPAC'16, Busan, Korea, May 2016, WEOBB01 |
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Slides TUCL02 [5.788 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUCL02 | ||
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TUPG01 | Beam Based Calibration of a Rogowski Coil Used as a Horizontal and Vertical Beam Position Monitor | storage-ring, dipole, pick-up, synchrotron | 302 |
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Electric Dipole Moments (EDMs) violate parity and time reversal symmetries. Assuming the CPT-theorem, this leads to CP violation, which is needed to explain the matter over antimatter dominance in the Universe. So far no direct EDM measurement for charged hadrons have been performed. The goal of the JEDI collaboration (Jülich Electric Dipole moment Investigations) is to measure the EDM of charged particles. The measurement of EDMs of charged hadrons can be performed in storage rings by observing a polarization build-up proportional to the EDM. Due to the smallness of the effect many systematic effects leading to a fake build-up have to be studied. A first step on the way for an EDM measurement is the investigation of systematic errors at the storage ring COSY (COoler SYnchrotron). One part of these studies is the control of the beam orbit with high precession. Therefore a concept of new Beam Position Monitors (BPMs) based on magnetic pick-up coils are used. The main advantage of the coil design is the high response to bunched beam frequency signal and the compactness of the coil itself. First measurement results of such a BPM accelerator environment will be presented. | |||
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Poster TUPG01 [1.827 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG01 | ||
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TUPG02 | A Novel Electron-BPM Front End With Sub-Micron Resolution Based on Pilot-Tone Compensation: Test Results With Beam | FPGA, storage-ring, pick-up, electron | 307 |
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In this paper we present a novel and original four channel front-end developed for a beam position monitor (BPM) system. In this work, we demonstrate for the first time the continuous calibration of the system using a pilot tone for both beam current dependency and thermal drift compensation, eliminating the need for thermoregulation. By using this original approach, we were also able to investigate several odd and well-known behaviours of BPM systems; the influence of important issues, like the non-linearity of ADCs and the gain compression of amplifiers which do affect the reliability of the measurement, have been fully understood. To achieve these results, we developed a new radio frequency front-end that combines the four pick-up signals originated by the beam with a stable and programmable tone, generated within the readout system. The signals from a button BPM of Elettra storage ring, have been acquired with a 16 bit - 160MS/s digitizer controlled by a CPU that evaluates the acquired data and applies the correction factor of the pilot tone. A final resolution equal to 1.0um, on a 20mm average radius vacuum chamber, has been measured with a long-term stability less than 1um. | |||
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Poster TUPG02 [3.671 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG02 | ||
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TUPG16 | Performance of Nanometre-Level Resolution Cavity Beam Position Monitors and Their Application in an Intra-Train Beam Position Feedback System | feedback, cavity, kicker, electron | 352 |
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A system of three low-Q cavity beam position monitors (BPMs), installed in the interaction point (IP) region of the Accelerator Test Facility (ATF2) at KEK, has been designed and optimised for nanometre-level beam position resolution. The BPMs have been used to provide an input to a low-latency, intra-train beam position feedback system consisting of a digital feedback board and a custom stripline kicker with power amplifier. The feedback system has been deployed in single-pass, multi-bunch mode with the aim of demonstrating intra-train beam stabilisation on electron bunches of charge ~1 nC separated in time by c. 220 ns. The BPMs have a demonstrated resolution of below 50 nm on using the raw measured vertical positions at the three BPMs, and has been used to stabilise the beam to below the 75 nm level. Further studies have shown that the BPM resolution can be improved to around 10 nm on making use of quadrature-phase signals and the results of the latest beam tests will be presented. | |||
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Poster TUPG16 [1.496 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG16 | ||
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TUPG51 | Micro Pattern Ionization Chamber with Adaptive Amplifiers as Dose Delivery Monitor for Therapeutic Proton LINAC | proton, electronics, linac, cathode | 464 |
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Funding: Regione Lazio: TOP-IMPLART project A dedicated dose delivery monitor is under development for the TOP-IMPLART proton accelerator, the first LINAC for cancer therapy. It is expected to measure the intensity profile to precisely monitor the fully active 3+1D (x/y/z and intensity) dose delivery of each short pulses (few micro-s, 0.1-10 micro-A pulse current at ~100 Hz) of the therapeutic proton beam (up to 230 MeV). The monitor system consists of planar gas chambers operating in ionization regime with cathode plane made ofμpattern pads alternately connected by orthogonal strips*. The dedicated readout electronics features trans-impedance amplifier that dynamically adapts its integrating feedback capacitance to the incoming amount of charge, then opportunistically changing its gain. The measured absolute sensitivity is about 100 fC (better than 0.03 relative sensitivity), the dynamic range up to 10000 (2 gain settings) with time response at the level of few ns, and virtually no dead time. Small scale chamber prototype (0.875 mm pitch pads) and readout electronics have been tested and characterized under both electron (5 MeV) and proton (up to 27 MeV) beams. * The pad-like design has been adopted to maximize the field uniformity, to reduce the chamber thickness and to obtain both x/y coordinates on a single chamber. |
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Poster TUPG51 [3.468 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG51 | ||
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TUPG68 | Study of the Radiation Damage on a Scintillating Fibers Based Beam Profile Monitor | detector, radiation, proton, extraction | 512 |
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The Scintillating Fibers Harp (SFH) monitors are the beam profile detectors used in the High Energy Beam Transfer (HEBT) lines of the CNAO (Centro Nazionale Adroterapia Oncologica, Italy) machine. The use of scintillating fibers coupled with a high-resolution CCD camera makes the detector of simple architecture and with high performances (less than 0.5mm resolution and 50Hz frame rate); on the other hand, fibers radiation damage shall be faced after some years of operation. The damage appears in multiple ways, as efficiency loss in light production, delayed light emission, attenuation length reduction. The work presents measurements and analysis performed to understand the phenomenon, in such a way to deal with it as best as possible. The connection between dose rate, integral dose and damage level is investigated as well as the possible recovery after a period of no irradiation. The influence of the damage effects on profiles reconstruction and beam parameters calculation is studied. Data elaboration is modified in such a way to compensate radiation damage effects and protract the SFH lifetime, before the major intervention of fibers replacement. Methods and results are discussed. | |||
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Poster TUPG68 [1.244 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG68 | ||
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TUPG72 | Calibration of X-ray Monitor during the Phase I of SuperKEKB commissioning | emittance, detector, scattering, optics | 524 |
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X-ray monitors (XRM) have been installed in each SuperKEKB ring, the Low Energy Ring (LER) and High Energy Ring (HER), primarily for vertical beam size measurement. Both rings have been commissioned in Phase I of SuperKEKB operation (February-June 2016), and several XRM calibration studies have been carried out. The geometrical scale factors seems to be well understood for both LER and HER. The emittance knob ratio method yielded results consistent with expectations based on the machine model optics (vertical emittance εy is {§I{≈8}{pm}}). For the HER, the vertical emittance εy is {§I{≈41}{pm}}, which is 4× greater than the optics model expectation. Analysis of beam size and lifetime measurements suggests unexpectedly large point response functions, particularly in the HER. | |||
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Poster TUPG72 [34.615 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG72 | ||
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WEPG62 | Incoherent and Coherent Polarization Radiation as Instrument of the Transversal Beam Size Diagnostics | radiation, polarization, target, diagnostics | 792 |
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Polarization radiation, which includes diffraction radiation (DR), transition radiation (TR), Smith-Purcell radiation, and others, can be a good instrument for beam diagnostics. All information about the beam size is contained in the so-called form-factor of the beam. The form-factor represents the sum of two parts corresponding to the coherent and incoherent radiation*. Contrary to the general opinion the incoherent part does not always equal unity*, **. In this report we give theoretical description of the incoherent and coherent parts of the form-factor both for Gaussian and uniform distribution of the ultrarelativistic particles in the bunch*, ***. The theory constructed describes also the case of beam skimming the target, which leads to mixing of DR and TR***. We show that the incoherent part depends on the transversal size of the beam, and dependence differs for different distributions. The role of the incoherent part of the form-factor of the bunch for different parameters is discussed.
* D.Yu. Sergeeva, A.A. Tishchenko et al., NIM B (2013) ** J.H. Brownell et al., PRE (1998); G. Doucas et al., PR STAB (2002) *** A.A. Tishchenko, D.Yu. Sergeeva et al., Vacuum (2016) |
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DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG62 | ||
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