Paper | Title | Other Keywords | Page |
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MOPAB141 | Terahertz Driven Compression and Time-Stamping Technique for Single-Shot Ultrafast Electron Diffraction | electron, laser, radiation, resonance | 492 |
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Funding: This research has been supported by the U.S. Department of Energy (DOE) under Contract No. DE-AC02-76SF00515 and DE-AC02-05-CH11231. Ultrafast structural dynamics are well understood through pump-probe characterization using ultrafast electron diffraction (UED). Advancements in electron diffraction and spectroscopy techniques open new frontiers for scientific discovery through interrogation of ultrafast phenomena, such as quantum phase transitions. Previously, we have demonstrated that strong-field THz radiation can be utilized to efficiently manipulate and compress ultrafast electron probes *, and also offer temporal diagnostics with sub-femtosecond resolution ** enabled by the inherent phase locking of THz radiation to the photoemission optical drive. In this work, we demonstrate a novel THz compression and time-stamping technique to probe solid-state materials at time scales previously inaccessible with standard UED. A high-frequency THz generation method using the organic OH-1 crystals is employed to enable a threefold reduction in the electron probes length and overall timing jitter. These time-stamped probes are used to demonstrate a substantial enhancement in the UED temporal resolution using pump-probe measurement in both photoexcited single crystal and polycrystalline samples. * E. C. Snively et al., Phys. Rev. Lett, vol. 124, no. 6, p. 054801, 2020. ** R. K. Li et al., Phys. Rev. Accel. Beams, vol. 22, no. 1, p. 012803, Jan. 2019. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB141 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 21 June 2021 issue date ※ 19 August 2021 | ||
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MOPAB153 | Laser Microfabrication for Accelerator Applications | laser, simulation, emittance, cathode | 535 |
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Laser microfabrication allows high precision ablation of materials at sub-mm scale. When laser pulse length is shorter than about 10 picoseconds the heat affected zone is minimized and ablation occurs without melting. Work-pieces processed in this fashion exhibit less structural damage and are expected to have a higher damage thresholds. In this paper we will review several case studies of laser-microfabricated components for accelerator and x-ray applications. Ablated materials include diamond, quartz, tungsten, copper, YAG:Ce and silicon. | |||
Poster MOPAB153 [2.781 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB153 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 29 August 2021 | ||
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MOPAB383 | Pressure Test for Large Grain and Fine Grain Niobium Cavities | cavity, niobium, SRF, experiment | 1173 |
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The pressure test was performed using a fine grain (FG) and a large grain (LG) niobium cavities. The cavity is 1.3 GHz 3-cell TESLA-like shape. The cavity was housed in a steel vessel. Water is supplied into the vessel and the cavity outside is pressurized. The applying pressure and the natural frequency of cavity were measured during the pressure test. The FG and LG cavities were deformed greatly and the pressure dropped suddenly at 3.4 MPa and 1.6 MPa, respectively. The frequency shifted up to 3.4 MHz and 1.3 MHz, respectively. There was no leak after the pressure test, so the cavity did not rupture under above pressure. The result of the pressure at LG cavity is less half than that of the FG cavity. We calculated the stress distribution in the structure by applying outer water pressure using a FEM. The maximum stress at cell when above test pressure is applied, are 146 MPa in FG and 73 MPa in LG, respectively. These stresses are similar to tensile strength of niobium specimen measure by ourselves. The result of pressure tests agrees well with the calculation. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB383 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 28 August 2021 | ||
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TUPAB386 | Design Study of the Nb3Sn Cos-Theta Dipole Model for FCC-hh | dipole, superconductivity, collider, FEL | 2421 |
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In the context of the Future Circular Collider hadron-hadron (FCC-hh) R&D program, the Italian Institute of Nuclear Physics (INFN), in collaboration with CERN, is responsible for designing and constructing the Falcon Dipole (Future Accelerator post-LHC Costheta Optimized Nb3Sn Dipole), which is an important step towards the construction of High Field Nb3Sn magnets for a post LHC collider. The magnet is a short model with one aperture of 50 mm and the target bore field is 12 T (14 T ’ultimate’ field). The dipole is pre-loaded with the Bladder&Key technique to minimize the stress on the coils at room temperature, which are prone to degradation because of the Nb3Sn cable strain-sensitivity. The electro-mechanical 2D design is focused on the performance, the field quality and the quench protection, with emphasis to the stresses on the the conductor. The Falcon Dipole has been modelled in a 3D FEM to determine the peak field distribution and the influence of the coil ends on the field quality. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB386 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 19 August 2021 | ||
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WEPAB286 | Design of the Laser-to-RF Synchronization at 1.3 GHz for SHINE | electron, laser, electronics, timing | 3323 |
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A next-generation photo-science facility like Shanghai HIgh repetition rate XFEL aNd Extreme light facility (SHINE) is aiming to generate femtosecond X-ray pulses with unprecedented brightness to film chemical and physical reactions with sub-atomic level spatio-temporal resolution. To fulfill this scientific goal, high-precision timing synchronization is essential. The pulsed optical synchronization has become an indispensable scheme for femtosecond precision synchronization of X-ray free-electron lasers. One of the critical tasks of pulsed optical synchronization is to synchronize various microwave sources. For the future SHINE, ultralow-noise pulses generated by a mode-locked laser are distributed over large distances via stabilized fiber links to all critical facility end-stations. In order to achieve low timing jitter and long-term stability of 1.3 GHz RF reference signal for the accuracy Low-Level RF(RF) field control, an Electro-optical intensity Modulator (EOM) based scheme is being developed at SHINE. In this paper, we present the progress on the design of the optical part and the integrated electronics of the laser-to-RF synchronization. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB286 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 12 July 2021 issue date ※ 28 August 2021 | ||
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WEPAB330 | A Multirange Low Noise Transimpedance Amplifier for Sirius Beamlines | impedance, feedback, operation, synchrotron | 3447 |
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In a typical synchrotron beamline, the interaction of photon beams with different materials generates free electric charges in devices such as ionization chambers, photodiodes, or even isolated metallic structures (e.g., blades, blocks, foils, wires). These free charges can be measured as electric current to diagnose the photon beam intensity, profile, position, or stability. Sirius, the new 3GeV fourth-generation Brazilian light source, may accommodate up to 38 beamlines, which combined will make use of hundreds of instruments to measure such low-intensity signals. This work reports on the design and test results of a transimpedance amplifier developed for low current measurements at Sirius’ beamlines. The device presents low noise, high accuracy, and good temperature stability providing 5 selectable ranges (from 500pA to 7.3mA) to measure bipolar currents achieving femtoampere resolution under certain conditions. Considering low bandwidth applications, the results suggest noise performance comparable to commercial bench instruments. Additionally, the project definitions and plans for the development of a family of low current ammeters will be discussed. | |||
Poster WEPAB330 [2.642 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB330 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 21 August 2021 | ||
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THPAB062 | Long-Wave IR Terawatt Laser Pulse Compression to Sub-Picoseconds | laser, simulation, experiment, plasma | 3893 |
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Funding: U.S. Department of Energy under contract DE-SC0012704 We report an experiment and simulations on post-compression of 2 ps, 0.15 TW CO2 laser pulses to 480 fs, ~0.25 TW by means of a self-phase modulation accompanied by a negative group dispersion in KCl and BaF2 optical slabs. In addition, down to 130 fs fine pulse structure, but at lower conversion efficiency, has been observed through self-compression in a bulk NaCl crystal. The obtained results surpass by far previous achievements in the ultra-fast long-wave IR laser technology |
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Poster THPAB062 [2.675 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB062 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 18 June 2021 issue date ※ 24 August 2021 | ||
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THPAB131 | Spatio-Temporal Measurements of THz Pulses | electron, polarization, radiation, laser | 4021 |
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Funding: This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory under Contract No. DEAC05-00OR22725. The 3D characterization of single-cycle Terahertz (THz) pulses in its transverse and temporal dimensions is presented. The high fields and short wavelengths of THz pulses make them an intriguing prospect for novel accelerator technologies. Effective application for free-space THz pulses requires high beam quality and concomitant measuring techniques. The combination of conventional electro-optic sampling to measure the temporal profile and detectors like microbolometer focal plane arrays to measure the transverse profile does not capture the correlations that can arise in single-cycle THz pulses. To capture these correlations, a modified version electro-optic sampling using a CCD is implemented. THz pulses generated by optical rectification in organic crystals are measured using this technique and their spatiotemporal correlations characterized. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB131 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 17 August 2021 | ||
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THPAB146 | Preliminary Study of Femtosecond Electron Source Based on THz Acceleration and Field Emission | electron, cavity, cathode, gun | 4048 |
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Funding: Work supported by National Natural Science Foundation of China (Grant No. U1832135 and 11805199) and Fundamental Research Funds for the Central Universities (Grant No. WK2310000072) In this paper, we propose a novel electron gun based on THz acceleration and field emission to generate femtosecond electron bunches. The field emission cathode is placed in the center of the cavity, and the standing wave field is established in the cavity to achieve the field emission conditions and extract the electron beam. Because the period of THz band is about picosecond, the femtosecond bunch is formed by controlling the field strength and the pulse width of the extracted beam. We analyzed the feasibility of field emission and the length of the pulse beam. The surface peak field intensity of the structure of the cavity with different emitters are simulated by CST software. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB146 | ||
About • | paper received ※ 09 May 2021 paper accepted ※ 02 September 2021 issue date ※ 01 September 2021 | ||
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THPAB307 | Behaviour of Ironless Inductive Position Sensors in Close Proximity to Each Other | simulation, ECR, collimation, site | 4390 |
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Funding: CERN - The European Organisation for Nuclear Research UM - The University of Malta Safety critical systems like the collimators of the Large Hadron Collider require transducers which are immune to interference from their surroundings. The ironless inductive position sensor is used to measure the position of collimator jaws with respect to the beam and is designed to be immune to external DC or slowly changing magnetic fields. In this paper we investigate whether frequency separation is required when multiple ironless inductive position sensors are used and whether two or more sensors at the same frequency results in cross-talk. Numerical simulations and experiments are conducted to study the magnetic field behaviour of the sensors, their interference with each other and the impact of this interference on the position reading. Finally, this paper defines guidelines on safe operation of the ironless inductive position sensor in the aforementioned conditions. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB307 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 02 July 2021 issue date ※ 22 August 2021 | ||
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THPAB314 | Development of the Femtosecond Timing Distribution System for the Shanghai Soft X-Ray Free Electron Laser | FEL, timing, laser, experiment | 4406 |
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High accuracy timing and synchronization system on femtosecond timescale play an important role for free-electron laser projects such as Shanghai Soft X-ray free-electron laser facility (SXFEL), and future Shanghai high repetition rate XFEL and Extreme light facility (SHINE). To meet the high precision synchronization requirements for both facilities, an optical-based timing distribution system is absolutely necessary. Such a system distributes the laser pulse train from a locked optical master oscillator through the fiber links, which stabilized by a balance optical cross-correlator based on a periodical-poled KTiOPO4 crystal. In this paper, the recent progress and experimental results of SXFEL and SHINE timing distribution system will be reported. | |||
Poster THPAB314 [0.351 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB314 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 15 July 2021 issue date ※ 22 August 2021 | ||
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