Silviu Covrig Dusa: Then and Now / 2012 Early Career Award Winner

WHAT DID THE 2012 EARLY CAREER AWARD ALLOW YOU TO DO?

Newswise — Probing matter at large scales is done with telescopes, while probing it at small scales is done with microscopes. An optical microscope uses light to probe on the scale of a millionth of a meter. At the Department of Energy’s Thomas Jefferson National Accelerator Laboratory (Jefferson Lab), we use a microscope to probe the structure of matter. It helps us try to answer fundamental questions in nuclear and particle physics to further our understanding of nature. 

Our microscope probes at subatomic scales using electron beams accelerated to high energies. As substrates for the electron beams, we use targets made of various materials, depending on what we measure. 

When an electron beam impinges onto a target material, it deposits heat along its path. The deposited heat in a target material produces target noise (random or unpredictable, unwanted signals). The most unwelcome effect of the target noise is to reduce the precision of measurements performed with the electron beam. 

To expand our knowledge beyond the Standard Model of particle physics, scientists require higher and higher precision measurements. One of the conditions to successfully perform such high precision measurements is to develop very low noise target systems.

To design and develop very low noise target systems for precision measurements in nuclear and particle physics, I used finite element software technologies called Computational Fluid Dynamics (CFD). The Early Career Award (ECA) allowed me and my colleagues to systematically determine the causes of target noise, mapping out its various tentacles. Along the way, I developed computational technologies with which I designed targets with more than an order of magnitude lower noise than before.

With a team from Jefferson Lab and the CFD tools that I developed with my ECA, I designed the highest power liquid hydrogen target in the world, at 4.5 kW, to be used in an electron beam. 

This target, part of the MOLLER experiment at Jefferson Lab, is predicted to have the lowest noise in its class. This characteristic will enable the MOLLER collaboration to perform the highest precision measurement of the weak mixing angle (a fundamental parameter of the Standard Model) at low energy.

ABOUT: 

Silviu Covrig Dusa is a staff scientist in the Physics Division at Thomas Jefferson National Accelerator Laboratory.

SUPPORTING THE DOE SC MISSION:

The Early Career Research Program provides financial support that is foundational to early career investigators, enabling them to define and direct independent research in areas important to DOE missions. The development of outstanding scientists and research leaders is of paramount importance to the Department of Energy Office of Science. By investing in the next generation of researchers, the Office of Science champions lifelong careers in discovery science. 

For more information, please go to the Early Career Research Program.

THE 2012 PROJECT ABSTRACT: 

Title: Computational Fluid Dynamics Facility to Support Targets for the 12 GeV Program at Jefferson Laboratory 

Abstract 

This project will establish a computational fluid dynamics (CFD) research program at the Thomas Jefferson National Accelerator Facility (TJNAF) to investigate and standardize the performance of liquid hydrogen targets for nuclear physics experiments. Liquid hydrogen has long been a standard target material for fixed‐target nuclear physics experiments at accelerator facilities worldwide. 

In the near future, experiments using very high intensity electron beams will require the removal of beam‐deposited heating of up to an order of magnitude beyond that which has been achieved with previous targets. Through CFD simulations, it should be possible to reduce target boiling effects by more than an order of magnitude, which will be crucial for the reduction of systematic errors in planned high beam intensity experiments. 

In this CFD research program, a range of experimental target designs will be simulated and optimized, including the 5000 W target envisioned for the possible ultra‐high precision MOLLER (Measurement Of a Lepton‐Lepton Electroweak Reaction) experiment at TJNAF, which proposes a precision study of high‐intensity polarized electron‐electron scattering. 

This CFD research program will also analyze safety issues and will develop standard procedures for operating liquid hydrogen targets in the safest manner feasible.

RESOURCES:

D Adhikari, et al. (PREX Collaboration), “Accurate Determination of the Neutron Skin Thickness of 208Pb through Parity-Violation in Electron Scattering.” Phys. Rev. Lett. 126, 172502 (2021). [DOI: 10.1103/PhysRevLett.126.172502]

D Adhikari, et al. (CREX Collaboration), “Precision Determination of the Neutral Weak Form Factor of 48Ca.” Phys. Rev. Lett. 129, 042501 (2022). [DOI: 10.1103/PhysRevLett.129.042501]

J Benesh, et al. (MOLLER Collaboration), “The MOLLER Experiment: An Ultra-Precise Measurement of the Weak Mixing Angle using Moller Scattering.” arXiv: 1411.4088v2, (2014). [DOI: 10.48550/arXiv.1411.4088]

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Additional profiles of the Early Career Research Program award recipients can be found at Early Career Program highlights page.

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