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This study analyzes a pulse-mode x-ray beam position monitor that enables pulse-by-pulse position measurement in a synchrotron radiation beamline of the synchrotron radiation facility, SPring-8. The monitor is equipped with blade-shaped detection elements utilizing diamond heatsinks to reduce stray capacitance and a microstripline transmission line to improve high-frequency characteristics. The detection elements operate as photocathodes and generate single unipolar pulses with a full width at half-maximum of less than 1 ns, allowing pulse-by-pulse measurement of the synchrotron radiation beam. We confirmed the basic operation of the monitor at the SPring-8 bending magnet beamline*. The detection element’s heat resistance consequently improved. An evaluation test was carried out at the SPring-8 undulator beamline with significantly high synchrotron radiation intensity. We aim to report the evaluation results of the sensitivity and resolution of the monitor measured by exciting a betatron oscillation in the horizontal/vertical direction using beam shakers of the SPring-8 storage ring and the observation results of the pulse-by-pulse photon beam dynamics induced by beam injection., Proceedings of the 11th International Beam Instrumentation Conference, IBIC2022, Kraków, Poland

The alignment of sextupole magnets is one of the critical issues for the upcoming 4th generation light sources and future colliders. The alignment error of magnets and the beam offsets in sextupoles should be within a few 10 µm rms to ensure enough dynamic aperture for stable operation and minimize deterioration of beam quality. Considering that the quadrupole field in a sextupole is proportional to the displacement (normal Q for horizontal and skew Q for vertical), we propose a beam-based calibration (BBC) method to measure the sextupole centers by observing the betatron tune shift. The magnetic center is the point where the tune does not change regardless of the sextupole field strength. The key is increasing the XY coupling to obtain a tune shift large enough for the vertical calibration. We studied experimentally the feasibility of the sextupole BBC at SPring-8 and successfully demonstrated the principle for both horizontal and vertical calibration. The tune shift was monitored by bunch-by-bunch feedback electronics with approximately 1e-5 resolution. The measurement resolution of the sextupole center was approximately 10 µm std., which was sufficient for our requirement., Proceedings of the 11th International Beam Instrumentation Conference, IBIC2022, Kraków, Poland

The beam injector for the SPring-8 storage ring (SR) was switched from the booster synchrotron to the SACLA linac, a driver for X-ray free-electron laser (XFEL). The low-emittance beam from SACLA (~100 pm rad, 8 GeV) is delivered to the SR through a 600m-long beam transport line. This low-emittance beam can be applied to the new low-emittance storage ring after the SPring-8 upgrade planed in the coming years. The shutdown of the booster synchrotron and 1-GeV linac saves energy consumption and operation cost. To provide the electron beam injected to the SR on demand for the top-up injection during the XFEL operation, the SACLA linac must be synchronized to the desired bucket of the SR, the beam energy and route must be switched shot-to-shot, and the XFEL performance must not be degraded. We developed a precise synchronization system, on-demand beam route and parameter switching system, a pulsed magnet for the switchyard, isolated bunch purification system, etc. In this presentation, we will show the design and performance of each component for the beam injection and the results from beam commissioning of the accelerator and transport line., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

We present a design overview of the beam diagnostic system for the new 3 GeV light source being constructed in Tohoku, Japan, and some test results obtained at SPring-8. This light source will generate brilliant x-rays from a high-quality electron beam having 1 nm rad emittance and 400 mA maximum stored current. To achieve the design performance and stability, we must monitor various beam parameters precisely. The beam position should be detected precisely: single-pass resolution < 0.1 mm (0.1 nC injected beam), COD resolution < 0.1 μm (more than 100 mA stored current), position stability < 5 μm for 1 month. We will use 112 button-type BPMs in the storage ring for these purposes. The stored beam current and beam size are also monitored with a DCCT and an x-ray pinhole camera. We will install a 3-pole wiggler to a straight section for the pinhole camera and other optical diagnostics. A stripline BPM and a stripline kicker will be installed to another straight section to suppress the beam instability and to measure betatron tune. We will use FPGA-based high-speed electronics for instability suppression with a bunch-by-bunch feedback method and real-time tune monitoring., IBIC 2020 - 9th International Beam Instrumentation Conference

We present a design overview of the beam diagnostic system for the new 3 GeV light source being constructed in Tohoku, Japan, and some test results obtained at SPring-8. This light source will generate brilliant x-rays from a high-quality electron beam having 1 nm rad emittance and 400 mA maximum stored current. To achieve the design performance and stability, we must monitor various beam parameters precisely. The beam position should be detected precisely: single-pass resolution 0.1 mm (0.1 nC injected beam), COD resolution 0.1 μm (more than 100 mA stored current), position stability 5 μm for 1 month. We will use 112 button-type BPMs in the storage ring for these purposes. The stored beam current and beam size are also monitored with a DCCT and an x-ray pinhole camera. We will install a 3-pole wiggler to a straight section for the pinhole camera and other optical diagnostics. A stripline BPM and a stripline kicker will be installed to another straight section to suppress the beam instability and to measure betatron tune. We will use FPGA-based high-speed electronics for instability suppression with a bunch-by-bunch feedback method and real-time tune monitoring., Proceedings of the 9th International Beam Instrumentation Conference, IBIC2020, Santos, Brazil

We have developed a new button-BPM readout electronics based on the MTCA.4 standard for the low-emittance upgrade of SPring-8 [*]. Requirements for the BPM system are a high single-pass BPM resolution of better than 100 µm for a 100 pC injected bunch to achieve first-turn steering in the commissioning of the upgraded ring and a highly stable COD BPM within 5 µm error for 1 month to maintain the optical axis of brilliant x-rays for users [**]. We designed an rf front-end rear transition module (RTM) having band-pass filters, low-noise amplifiers, step attenuators, and calibration tone generators. The rf signal is detected by a 16-bit 370 MSPS high-speed digitizer advanced mezzanine card (AMC) developed for the new low-level rf system of SPring-8 [***]. The firmware of the FPGA on the digitizer AMC was newly developed to implement various functions of the BPM system. We evaluated the readout system at a laboratory and then tested at the present SPring-8 storage ring with a prototype BPM head for the SPring-8 upgrade. We confirmed that the new readout system satisfies the requirements for the single-pass BPM resolution and the COD BPM stability., Proceedings of the 8th International Beam Instrumentation Conference, IBIC2019, Malmö, Sweden

We are developing a new electron beam position monitor (BPM) system for the low-emittance upgrade of SPring-8. The requirements for the BPM system are: (1) a single-pass resolution of 100 µm rms for a 100 pC bunch and an electric center accuracy of 100 µm rms for the initial beam commissioning to achieve the first turn, (2) a closed-orbit distortion (COD) resolution better than 0.1 µm rms for a 100 mA stored beam and a position stability of less than 5 µm for the ultimate stability of a photon beam axis. We have completed prototypes of a precise button electrode and a BPM block to obtain high-intensity signals and sufficient mechanical accuracy while suppressing high-Q trapped modes leading to impedance and heating issues. The development of readout electronics based on the MTCA.4 standard and the evaluation of radiation-hard coaxial cables have also been conducted. The prototype BPM head was installed in the present SPring-8 storage ring for performance verification with an actual electron beam. We confirmed sufficient signal intensity, electric center accuracy, position stability, etc. by the beam test. The new BPM system is almost ready for the SPring-8 upgrade., Proceedings of the 7\textsuperscript{th} Int. Beam Instrumentation Conf., IBIC2018, Shanghai, China