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At least 1,279 records · Page 71

Conceptual Design of a HTS Dipole Insert Based on Bi2212 Rutherford Cable

The U.S. Magnet Development Program (US-MDP) is aimed at developing high-field accelerator magnets with magnetic fields beyond the limits of Nb 3 Sn technology. Recent progress with composite wires and Rutherford cables based on the first generation high-temperature superconductor Bi 2 Sr 2 CaCu 2 O 8-x (Bi2212) allows considering them for this purpose. However, Bi2212 wires and cables are sensitive to transverse stresses and strains, which are large in high-field accelerator magnets. This requires magnet designs with stress management concepts to control azimuthal and radial strains in the coil windings and prevent the degradation of the current carrying capability of Bi2212 conductor or even its permanent damage. This paper describes a novel stress management approach, which was developed at Fermilab for high-field large-aperture Nb 3 Sn accelerator magnets, and is now being applied to high-field dipole inserts based on Bi2212 Rutherford cables. The insert conceptual design and main parameters, including the superconducting wire and cable, as well as the coil stress management structure, key technological steps and approaches, test configurations and their target parameters, are presented and discussed.

43 PARTICLE ACCELERATORS↗

Gold-gold luminosity increase in RHIC for a beam energy scan with colliding beam energies extending below the nominal injection energy

The Beam Energy Scan phase II (BES-II), performed in the Relativistic Heavy Ion Collider (RHIC) from 2019 to 2021, explored the phase transition between quark-gluon plasma and hadronic gas. BES-II exceeded the goal of a fourfold increase in the average luminosity over that achieved during Beam Energy Scan phase I (BES-I), at five gold beam energies: 9.8, 7.3, 5.75, 4.59, and 3.85 GeV / nucleon. This was accomplished by addressing several beam dynamics effects, including intrabeam scattering, beam-beam, space charge, beam instability, and field errors induced by superconducting magnet persistent currents. Some of these effects are especially detrimental at low energies. BES-II achievements are presented, and the measures taken to improve RHIC performance are described. These measures span the whole RHIC complex, including ion beam sources, injectors, beam lifetime improvements in RHIC, and operation with the world’s first bunched beam Low Energy RHIC electron Cooler (LEReC).

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femto-PIXAR: a self-supervised neural network method for reconstructing femtosecond X-ray free electron laser pulses

X-ray Free Electron Lasers (X-FELs) operate in a wide range of lasing configurations for a broad variety of scientific applications at ultrafast time-scales such as structural biology, materials science, and atomic and molecular physics. Shot-by-shot characterization of the X-FEL pulses is crucial for analysis of many experiments as well as tuning the X-FEL performance. However, for the weak pulses found in advanced configurations, e.g. those needed for coherent, two-pulse studies of quantum materials, there is no current method for reliably resolving pulse profiles. Here we show that a physics-based U-net model can reconstruct the individual pulse power profiles for sub-picosecond pulse separation without the need for simulations. Using experimental data from weak X-FEL pulse pairs, we demonstrate we can learn the pulse characteristics on a shot-by-shot basis when conventional methods fail.

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SEM Grid Testing at NLCTA in BeamNetUS Program

We report on the performance of a secondary electron monitor (SEM) grid used to measure the transverse profile of an MeV range electron beam at SLAC National Accelerator Laboratory’s Next Linear Collider Test Accelerator (NLCTA) facility. When inserted into the path of the electron beam, secondary electron emission results in a measurable current on the wires that make up the grid. We present measurements using this technique to reconstruct the beam profile. The SEM grid was designed and manufactured by a team of undergraduate students at Harvey Mudd College (HMC) and was tested at SLAC’s NLCTA facility in collaboration with NCLTA staff as part of the BeamNetUS program. Developed for real-time diagnostics of MeV-range electron beams, this SEM grid has potential applications in both industrial and medical contexts.

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Adaptation of the Fermilab proton source to support new muon facilities

The PIP-II proton accelerator will provide the intensity sufficient to power a new generation of high energy facilities at Fermilab. Extension of that linac to higher energy with following acceleration and bunching rings could provide the intensity needed to feed a muon production target for a high-energy $\mu^{+} - \mu^{-}$ collider. Scenarios using a rapid-cycling synchrotron or an $\sim$8 GeV Linac are presented and discussed. Some near-term opportunities at Fermilab for muon collider R\&D are introduced.

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Sextupole Misalignment and Defect Identification and Remediation in IOTA

The nonlinear integrable optics studies at the integrable optics test accelerator (IOTA) demand fine control of the chromaticity using sextupole magnets. During the last experimental run undesirable misalignments and multipole composition in some sextupole magnets impacted operations. This report outlines the beam-based methods used to identify the nature of the misalignments and defects, and the subsequent magnetic measurements and remediation of the magnets for future runs.

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Adaptation of the Fermilab Proton Source to Support New Muon Facilities

he PIP-II proton accelerator will provide the intensity sufficient to power a new generation of high energy facilities at Fermilab. Extension of that linac to higher energy with following acceleration and bunching rings could provide the intensity needed to feed a muon production target for a high-energy $\mu^{+} - \mu^{-}$ collider. Scenarios using a rapid-cycling synchrotron or an $\sim$8 GeV Linac are presented and discussed. Some near-term opportunities at Fermilab for muon collider R&D are introduced.

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Linearization of an Electron Beam’s Longitudinal Phase Space Using a Hollow-Channel Plasma

The removal of undesired beam nonlinear energy chirp (time-energy correlation) or linearization of the beam longitudinal phase space (LPS) is crucial for high-brightness linac-based scientific applications, such as x-ray free-electron lasers. In this paper, we propose that a low-density hollow channel plasma can be used as a near-ideal passive linearizer to significantly linearize the beam LPS and, at the same time, preserve the beam emittance. Physically, the passage of the beam through the hollow plasma channel excites a strong quasicosinoidal longitudinal wakefield that acts to mitigate the beam nonlinear energy chirp by superimposing a reverse chirp on the beam. The theoretical analyses and large-scale three-dimensional start-to-end simulations confirm that the beam longitudinal phase space can be almost completely linearized without noticeable beam emittance growth. In conclusion, application of such a near-ideal linearizer may significantly improve the performance of numerous accelerator-based applications.

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Light and Electron Emission as Breakdown Probes: Synergistic DC and RF Study

The project was motivated by a particular and critical need in accelerator R&D to understand vacuum breakdown and arc as it would allow for developing high gradient machines. Accelerator systems operated at high gradients are less costly and more compact. This, in turn, would enable advanced and cost-effective accelerators for future colliders. Universities and medical centers would be able to build compact accelerator machines for basic X-ray and microscopy sciences, therapy, isotope production, sterilization etc.

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Fast cycling HTS based superconducting accelerator magnets: Feasibility study and readiness demonstration program driven by neutrino physics and muon collider needs

Development of energy-efficient fast cycling accelerator magnets is critical for the next generation of proton rapid cycling synchrotrons (RCS) for neutrino research and booster accelerators of future muon colliders. We see a unique opportunity for having such magnets to be built on base of High Temperature Superconductors (HTS). Besides being superconducting at relatively high temperatures, rare-earth HTS tapes have shown very small AC losses compared to low-temperature NbTi superconductor cables. Recent tests of the HTS-based 0.5 m long two-bore superconducting accelerator magnet have shown record high dB/dt ramping rates of about 300 T/s at 10 Hz repetition rate and 0.5 T B-field span. No temperature rise in 6 K cooling He was observed within the 0.003 K error setting the upper limit on the cryogenic power loss in the magnet conductor coil to be less than 0.2 W/m. Based on this result we outline a possible upgrade of this test magnet design to 2 T B-field in the 10 mm beam gap with the dB/dt ramping rates up to 1000 T/s. The power test results of this short sample magnet will be used to project both cryogenic and electrical power losses as a function of the magnet B-field and the dB/dt ramping rates. Then these projections will be scaled to the range of expected accelerator magnet beam gaps and B-fields for the proton and muon RCS accelerators. We invite collaborators to join these studies and call for support of the R&D program aimed at comprehensive demonstration of this approach that includes design, construction, and power tests of a long prototype of the HTS-based fast-cycling accelerator magnet by 2028.

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Beam Dynamics simulations for ERDC project -- SRF linac for industrial use

Compact conductively cooled SRF industrial linacs can provide unique parameters of the electron beam for industrial applications. (up to 10MeV, 1MW). For ERDC project we designed normal conducting RF injector with thermal RF gridded gun integrated in first cell of multi-cell cavities. For design of the RF gun we used MICHELLE software to simulate and optimize parameters of the beam. Output file was converted to ASTRA format and most beam dynamic simulations in multi-cell normal conducting cavity and cryomodule were performed by using ASTRA software. For cross-checking we compare results of MICHELLE and AS-TRA in first few cells. At the end of injector beam reach ~250keV energy which allow to trap bunch in acceleration regime without losses in TESLA like 1.3 GHz cavity. Short solenoid at the end of injector allow to regulate transverse beam size in cryomodule to match beam to extraction system and also reduce charge losses in accelerator.

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Conductor Properties and Coil Technology for a Bi2212 Dipole Insert for 20 Tesla Hybrid Accelerator Magnets

A dipole insert based on a 2-layer cos-theta coil with stress management and Bi2212 superconducting strand and cable is being developed at Fermilab as part of the US-MDP effort. The ultimate goal of this task is to develop coil technology and an approach to manage azimuthal and radial strains of high temperature superconductor inserts when integrated within Nb3Sn outserts as a hybrid magnet system. This note reviews conductor properties and possible coil technologies.

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Dark Matter and other BSM searches with SRF cavities at SQMS

The Superconducting Quantum Materials and Systems Center, led by Fermi National Accelerator Laboratory, is one of five research centers funded by the U.S. Department of Energy as part of a national initiative to develop and deploy the world’s most powerful quantum computers and sensors. The SQMS Center uses world-record quality-factor superconducting radio-frequency, or SRF, cavities as ultra-sensitive quantum probes. Cavities combined with superconducting transmon qubits can be the building block of a quantum computer, and they can also be employed for fundamental physics searches. Within the quantum sensing thrust, researchers are developing experiments based on cavities and novel quantum devices to search for particles beyond the Standard Model, dark matter candidates, gravitational waves and fundamental material properties. The seminar will present a brief overview of the center and focus on the physics and sensing work conducted at Fermilab.

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Rapid-cycling HTS magnet for muon acceleration

A very wide range of operational temperatures of the HTS (YBCO) superconductor makes it suitable for the construction of rapid-cycling magnets required for the muon acceleration. The measured [3] very low power loss of the 0.4 T magnet operating at 300 T/s suggested a realistic possibility of the HTS-based accelerator magnet with much higher magnetic field and ramp rate. The magnet core and the HTS cable designs for the 2 T field in the 30 mm beam gap are presented. The simulation of the HTS cable hysteresis power loss for the 1000 T/s ramp rate is discussed in terms of the operational temperatures and required cryogenic power.

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