Bruno Rossi Distinguished Postdoctoral Fellowship; Senior Scientist

Job Description

Mission Support and Test Services, LLC (MSTS) manages and operates the Nevada National Security Site (NNSS) for the U.S. National Nuclear Security Administration (NNSA). Our mission is to help ensure the security of the United States and its allies by providing high‑hazard experimentation and incident response capabilities through operations, engineering, education, field, and integration services and by acting as environmental stewards to the Site's Cold‑War legacy.

Our vision is to be the user site of choice for large‑scale, high‑hazard, national security experimentation, with premier facilities and capabilities below ground, on the ground, and in the air.

• MSTS offers our full‑time employees highly competitive salaries and benefits packages including medical, dental, and vision; both a pension and a 401k; paid time off and 96 hours of paid holidays; relocation (if located more than 75 miles from work location); tuition assistance and reimbursement; and more.
• MSTS is a limited liability company consisting of Honeywell International Inc. (Honeywell), Jacobs Engineering Group Inc. (Jacobs), and HII Nuclear Inc.

The NNSS Science & Technology Directorate invites exceptional early‑career scientists to apply for the Bruno Rossi Distinguished Postdoctoral Fellowship. The Rossi Fellow will drive advances in the theory, computational modeling, and/or machine‑learning applications to the Scorpius linear induction accelerator (LIA) – one of the Nation's flagship capabilities supporting NNSA missions. This is a high‑impact, publication‑friendly role embedded with a senior NNSS mentor and collaborating laboratories.

• Accelerator & Beam Physics (Theory/Computation)
• Relativistic Beam‑Target Interaction Physics:
  Investigating beam interactions with complex bremsstrahlung converters, including X‑ray source modeling, dose and fluence optimization, and converter survivability under advanced material responses.
• Beam Transport in Complex Environments:
  Studying beam transport in solenoidal and induction systems, with emphasis on emittance preservation, halo formation and mitigation, and energy spread control under realistic operating conditions.
• Collective Effects and Instabilities:
  Developing models and mitigation strategies for phenomena such as Beam Breakup (BBU), corkscrew motion, and transverse/longitudinal impedance‑driven instabilities.
• Pulsed‑Power and Accelerator Coupling:
  Exploring circuit‑beam co‑simulation, magnet and induction module dynamics, and timing and waveform shaping to enhance stability and brightness.
• Diagnostics by Design:
  Creating inference methods and synthetic diagnostics to extract critical machine parameters (emittance, current, energy, spot size, and centroid motion) from limited data, while incorporating uncertainty quantification and error budgets for machine studies.
• Multiphysics Target Response:
  Modeling the Magneto‑Hydrodynamics (MHD) and thermomechanics of converter materials under intense pulsed loading, including shock and thermal fatigue, to evaluate lifetime and performance trade‑offs.

• Particle‑In‑Cell (PIC) and Vlasov‑Fokker‑Planck simulations, hybrid PIC‑fluid models, envelope and moment techniques, Monte Carlo radiation transport, surrogate modeling, adjoint and gradient‑based optimization, as well as rigorous uncertainty quantification (UQ) and sensitivity analysis.
• Machine Learning, Artificial Intelligence, and Digital Twin Foundations for the Scorpius Accelerator
• Data‑Driven Machine Tuning:
  Optimizing accelerator performance by leveraging cutting‑edge methods to rapidly identify optimal set points and compensate for beam drifting across multiple shots and variable thermal states.
• Predictive Maintenance and Anomaly Detection:
  Applying time‑series modeling to pulsed‑power components and beam diagnostics for fault prediction, remaining useful life estimation, and automated alert systems.
• Physics‑Constrained Machine Learning:
  Implementing novel neural network architectures and reduced‑order modeling techniques, constrained by first‑principles physics, to deliver fast and explainable…