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At least 19 records

Microphonics in the LCLS-II Superconducting Linac

The LCLS-II project has installed a new superconducting linac at SLAC that consists of 35 1.3 GHz cryomodules and 2 3.9 GHz cryomodules. The linac will provide a 4 GeV electron beam for generating soft and hard X-ray pulses. Cavity detuning induced by microphonics was a significant design challenge for the LCLS-II cryomodules. Cryomodules were produced that were within the detuning specification (10 Hz for 1.3 GHz cryomodules) on test stands. Here we present first measurements of the microphonics in the installed LCLS-II superconducting linac. Overall, the microphonics in the linac are manageable with 94% of cavities coming within the detune specification. Only two cavities are gradient limited due to microphonics. We identify a leaking cool down valve as the source of microphonics limiting those two cavities.

43 PARTICLE ACCELERATORS↗

LLRF System Analysis for the Fermilab PIP-II Superconducting LINAC

PIP-II is a superconducting linac that is in the initial acceleration chain for the Fermilab accelerator complex. The RF system consists of a warm front-end with an RFQ and buncher cavities along with 25 superconducting cryo-modules comprised of cavities with five different acceleration \(β\). The LLRF system for the linac has to provide field and resonance control for a total of 125 RF cavities. Various components of the LLRF system have been tested with and without beam at the PIP-II test stands. The LLRF system design is derived from the LCLS-II project with its self-excited loop architecture used in the majority of the cryo-modules. The PIP-II beam loading at 2 mA is much higher than the LCLS-II linac. The control system architecture is analyzed and evaluated for the operational limits of feedback gains and their ability to meet the project regulation requirements for cavity field amplitude and phase regulation.

Varghese, P. [Fermilab] (ORCID:0009000925131983)↗

LLRF System for the Fermilab PIP-II Superconducting LINAC

PIP-II is an 800 MEV superconducting linac that is in the initial acceleration chain for the Fermilab accelerator complex. The RF system consists of a warm front-end with an ion source, RFQ and buncher cavities along with 25 superconducting cryo-modules comprised of five different acceleration \(\beta\). The LLRF system for the LINAC has to provide field and resonance control for a total of 125 RF cavities.The LLRF system design is in the final design review phase and will enter the production phase next year. The PIP-II project is an international collaboration with various partner labs contributing subsystems. The LLRF system design for the PIP-II Linac is presented and the specification requirements and system performance in various stages of testing are described in this paper.

43 PARTICLE ACCELERATORS↗

Optimization of Superconducting Linac for Proton Improvement Plan-II (PIP-II)

PIP-II is an essential upgrade of the Fermilab complex that will enable the worlds most intense high-energy beam of neutrinos for the international Deep Underground Neutrino Experiment at LBNF and support a broad physics program at Fermilab. Ultimately, the PIP-II superconducting linac will be capable of accelerating the $H-$ CW beam to 800 MeV with an average power of 1.6 MW. To operate the linac with such high power, beam losses and beam emittance growth must be tightly controlled. In this paper, we present the results of global optimization of the Linac options towards a robust and efficient physics design for the superconducting section of the PIP-II linac. We also investigate the impact of the nonlinear field of the dipole correctors on the beam quality and derive the requirement on the field quality using statistical analysis. Finally, we assess the need to correct the quadrupole focusing produced by Half Wave, and Single Spoke accelerating cavities. We assess the feasibility of controlling the beam coupling in the machine by changing the polarity of the field of linac focusing solenoids

43 PARTICLE ACCELERATORS↗

Controls at the Fermilab PIP-II Superconducting Linac

PIP-II is an 800 MeV superconducting RF linac under development at Fermilab. As the new first stage in our accelerator chain, it will deliver high-power beam to multiple experiments simultaneously and thus drive Fermilab’s particle physics program for years to come. In a pivot for Fermilab, controls for PIP-II are based on EPICS instead of ACNET, the legacy control system for accelerators at the lab. This paper discusses the status of the EPICS controls work for PIP-II. We describe the EPICS tools selected for our system and the experience of operators new to EPICS. We introduce our continuous integration / continuous development environment. We also describe some efforts at cooperation between EPICS and ACNET, or efforts to move towards a unified interface that can apply to both control systems.

43 PARTICLE ACCELERATORS↗

Controls at the Fermilab PIP-II Superconducting Linac

PIP-II is an 800 MeV superconducting RF linear accelerator under development at Fermilab. As the new first stage in our accelerator chain, it will deliver high-power beam to multiple experiments simultaneously and thus drive Fermilab's particle physics program for years to come. In a pivot for Fermilab, controls for PIP-II are based on EPICS instead of ACNET, the legacy control system for accelerators at the lab. This paper discusses the status of the EPICS controls work for PIP-II. We describe the EPICS tools selected for our system and the experience of operators new to EPICS. We introduce our continuous integration / continuous development environment. We also describe some efforts at cooperation between EPICS and ACNET, or efforts to move towards a unified interface that can apply to both control systems.

43 PARTICLE ACCELERATORS↗

Design options for a superconducting ion linac

Following a review of the design options for a superconducting ion linac, we present here an alternative design for the pre-stripper section of the superconducting driver linac for the rare isotope science project (RISP) of the Institute for Basic Science in Korea. The proposed alternative design takes advantage of the recent accelerator developments at Argonne, namely for the recent ATLAS intensity and efficiency upgrade and the Fermilab proton improvement plan project (PIP-II). In particular, the state-of-the-art performance of quarter-wave (QWRs) and half-wave resonators (HWRs), the integrated steering correctors and cold beam position monitors (BPMs) for a compact cryomodule design. In order to simplify the design and avoid frequency transitions, we used two types of QWRs at 81.25 MHz while the baseline design has QWRs at 81.25 MHz and HWRs at 162.5 MHz. The new QWR types were optimized for β ~0.05 and ~0.11, respectively, and corrected for beam steering effects. Nine cryomodules are required to reach the stripping energy of 18.5 MeV/u for uranium beam. An alternative radio-frequency quadrupole (RFQ) design was also developed. It is optimized with the multi-harmonic buncher (MHB) to produce a much smaller longitudinal emittance, offering much needed flexibility for beam tuning and more tolerance to errors. Following the lattice design optimization, end-to-end beam dynamics simulations including most important sources of machine error were performed. The results showed that the design is robust and tolerant to errors with no beam loss observed for typical machine errors.

43 PARTICLE ACCELERATORS↗

Design of a non-invasive laser-based beam profile monitor system for the new Fermilab PIP-II superconducting H- linac

As part of the new Proton Improvement Plan (PIP-II), Fermilab is undertaking the development of a new 800 MeV, 2 mA H- superconducting RF linac to replace its present normal conducting 400 MeV linac. The PIP-II linac consists of a series of superconducting RF cryomodules from 2.1 MeV to 800 MeV. To limit the potential damage to the superconducting RF cavities, PIP-II will utilize non-invasive laser-based monitors (laserwires) to obtain beam profiles via photoionization. This paper will present the design of this PIP-II laserwire system including the picosecond pulsed laser, optical transport line, 13 individual laserwire stations, laser feedback and timing controls. The paper also describes the signal detection system and operation of the profile measurements.

Scarpine, Victor [Fermilab]↗

Design of a Non-Invasive Laser-based Beam Profile Monitor System for the New Fermilab PIP-II Superconducting H- Linac

As part of the new Proton Improvement Plan (PIP-II), Fermilab is undertaking the development of a new 800 MeV, 2 mA H- superconducting RF linac to replace its present normal conducting 400 MeV linac. The PIP-II linac consists of a series of superconducting RF cryomodules from 2.1 MeV to 800 MeV. To limit the potential damage to the superconducting RF cavities, PIP-II will utilize non-invasive laser-based monitors (laserwires) to obtain beam profiles via photoionization. This paper will present the design of this PIP-II laserwire system including the picosecond pulsed laser, optical transport line, 13 individual laserwire stations, laser feedback and timing controls.

Scarpine, V. [Fermilab]↗

Digital twin framework for PIP-II linac: AI-driven multi-scale modeling from ion source to 800 MeV

The PIP-II superconducting linac at Fermilab is designed to deliver multi-megawatt proton beams for neutrino physics and other high-intensity applications. To expedite commissioning and enhance operational reliability, we have developed an EPICS-based data flow framework that seamlessly integrates digital twins (DT) with physical twins (PT). These digital twins comprise high-fidelity beam dynamics models or data-driven surrogate models connected to their physical counterparts through real-time diagnostics and advanced machine-learning algorithms.Central to this framework is Linac_Gen, an accelerated simulation tool that incorporates convolutional neural networks, random forests, and genetic algorithms to provide up to a tenfold speedup in optimizing the accelerator geometry model. An EPICS translator layer ensures interoperability by efficiently mapping lattice parameters across diverse simulation platforms.Our EPICS-based framework supports multiple operational modes—monitoring, passive learning, closed-loop control, and online learning—covering the entire machine lifecycle. By leveraging HPC resources and multi-objective optimization techniques, the digital twin enables adaptive trajectory correction, real-time fault detection, and predictive modeling of beam stability. This comprehensive approach paves the way for robust, high-intensity operation and data-driven accelerator R&D at Fermilab.

Pathak, Abhishek [Fermilab]↗

Geant4 Simulations on Faraday Cup Design for PIP-II Laser Wire Scanner System

The Proton Improvement Plan-II (PIP-II) accelerator upgrade at Fermilab represents a groundbreaking leap forward in high-energy physics research. This ambitious initiative involves enhancing Fermilab's accelerator complexby replacing the current linear accelerator (linac) with awarm front end (WFE) capable of accelerating H- beamsup to 2.1 MeV. Subsequently, a superconducting linac further accelerates these beams up to 800 MeV. To preciselymeasure the transverse beam profile, a combination of traditional wire scanners at the WFE section and Laser wirescanners along the superconducting linac are planned forimplementation. This investigation is centered on refiningthe Faraday cup design for the PIP-II Laser wire scannersby utilizing GEANT4, a Monte Carlo simulation toolkit.Leveraging this method enables a comprehensive analysisof particle trajectories, energy deposition, secondary particle emission, backscattering, etc., facilitating optimizationthrough adjustments to cup geometries, materials, andplacement to maximize its efficacy in beam diagnostics.

43 PARTICLE ACCELERATORS↗

GEANT4 Simulations on Faraday Cup Design for PIP-II Laser Wire Scanner System

The PIP-II accelerator upgrade at Fermilab represents a groundbreaking leap forward in high-energy physics research. This ambitious initiative involves enhancing Fermilab's accelerator complex by replacing the current linear accelerator with a warm front end (WFE) capable of accelerating H- beams up to 2.1 MeV. Subsequently, a superconducting linac further accelerates these beams up to 800 MeV. To precisely measure the transverse beam profile, a combination of traditional wire scanners at the WFE section and Laser wire scanners along the superconducting linac are planned for implementation. This investigation centers on refining the Faraday cup design for the PIP-II Laser wire scanners by utilizing GEANT4, a Monte Carlo simulation toolkit. Leveraging this method enables a comprehensive analysis of particle trajectories, energy deposition, secondary electron emission, backscattering, etc., facilitating optimization through adjustments to cup geometries, materials, and placement to maximize its efficiency.

43 PARTICLE ACCELERATORS↗