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Silviu Covrig Dusa: yesterday and today / Winner of the 2012 Early Career Award


Probing matter on a large scale is done with telescopes, while probing on a small scale 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. This helps us try to answer fundamental questions in nuclear physics and particle physics to deepen our understanding of nature.

Our microscope probes at subatomic scales using high-energy accelerated electron beams. As substrates for the electron beams, we use targets made of different materials, depending on what we are measuring.

When an electron beam hits a target material, it deposits heat along its path. Heat deposited in a target material produces target noise (random or unpredictable and unwanted signals). The most undesirable effect of target noise is to reduce the accuracy of measurements made with the electron beam.

To expand our knowledge beyond Standard Model of Particle Physics, scientists need increasingly precise measurements. One of the conditions for successful measurements of such precision is to develop very low noise target systems.

To design and develop ultra-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, by mapping its various tentacles. Along the way, I developed computer technologies with which I designed targets with noise more than an order of magnitude lower than before.

With a team at Jefferson Lab and the CFD tools I developed with my ECA, I designed the world’s most powerful liquid hydrogen target, at 4.5 kW, for use in an electron beam.

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


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


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

For more information, please visit the Early Career Research Program.


Title: Computational Fluid Dynamics Facility to Support the Goals of the 12 GeV Program at Jefferson Laboratory


This project will establish a computational fluid dynamics (CFD) research program at the Thomas Jefferson National Accelerator Facility (TJNAF) to study 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. accelerator facilities global.

In the near future, experiments using very high intensity electron beams will require suppression of the heating deposited by the beam to an order of magnitude greater than that achieved with previous targets. Using CFD simulations, it should be possible to reduce target boiling effects by more than an order of magnitude, which will be crucial for reducing systematic errors in planned beam-intensive experiments.

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

This CFD research program will also analyze safety issues and develop standard procedures for operating liquid hydrogen targets as safely as possible.


D Adhikari, et al. (PREX collaboration), “Precise determination of the thickness of the neutron skin of 208Pb by parity violation in electron scattering. » Phys. Reverend Lett. 126, 172502 (2021). (DOI: 10.1103/PhysRevLett.126.172502)

D Adhikari, et al. (CREX collaboration), “Precise determination of the weak neutral form factor of 48Ca”. Phys. Reverend 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 diffusion. » arXiv: 1411.4088v2, (2014). (DOI: 10.48550/arXiv.1411.4088)

The DOE explains… offers simple explanations of key basic science words and concepts. It also describes how these concepts apply to the work conducted by the Department of Energy’s Office of Science, which helps the United States excel in research in all areas of science. For more information on the Standard Model of particle physics, particle accelerators, and DOE research in this area, please see “DOE explains…the Standard Model of particle physics” And “DOE Explains… Particle Accelerators.”

Additional profiles of the Early Career Research Program winners can be viewed at Early Career Program Highlights Page.

The Office of Science is the largest supporter of basic research in the physical sciences in the United States and strives to address some of the most pressing challenges of our time. For more information, please visit Office of Science website.

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