Or Hen (physicist)

Or Hen is an Israeli-born Associate Professor of nuclear and particle physics at the Massachusetts Institute of Technology (MIT) and Fellow of the American Physical Society (APS). He works on studies of quantum chromodynamics (QCD) effects in the nuclear medium using measurements of high-energy scattering processes and the development of the U.S. Electron-Ion Collider.
==Early life and education==
Hen was born in Jerusalem, Israel, growing up in a family of poultry farmers in moshav Even Sapir. As a child he struggled with severe learning disabilities, being diagnosed in kindergarten with a neurological disorder called dysgraphia . Hen started attending Hebrew University while attending high school, as part of the Lehava program, which makes academia more accessible to first-generation high school students by allowing them to experience taking college-level classes while still in high school. Through the Lehava program, Hen developed an interest in STEM and quickly gravitated towards physics.
After completing high school, Hen attended Hebrew University as a full-time student, completing a double major bachelor's degree in physics and computer engineering in 2009. He then joined the Israeli Army, where he served as a senior academic officer for about seven years, performing experimental physics research. In parallel to his army service, Hen joined the research group of Eli Piasetzky at Tel-Aviv University, obtaining a graduate degree in physics in 2015.
==Research and career==
Hen moved to the US in late 2015 to join the MIT Physics Department and Laboratory for Nuclear Science, first as a distinguished Pappalardo Fellow in physics (from 2015 to 2017), and then as a faculty member (starting July 2017). In 2021 Hen was promoted to the rank of associate professor and named the Class of 1956 CD Associate Professor of Physics.
Correlations and the EMC Effect:
Hen's main research work measures the scattering of high-energy electrons, neutrinos, photons, and protons from atomic nuclei to probe for short-range correlations (SRCs): "Quantum Mechanical fluctuations of high-density, high-momentum, nucleon clusters in nuclei". Due to their overlapping quark distributions and strong interaction, SRC pairs serve as a bridge between low-energy nuclear structure, high-density nuclear matter, and high-energy quark distributions (the EMC effect); with important consequences for strong-interaction physics, hadronic structure and astrophysics.
By analyzing measurements of hard electron- and proton-induced SRC pair breakup reactions, Hen and collaborators showed that SRC pairs account for almost all high-momentum (k>k_F) nucleons in the nucleus. and mapped the single-particle to correlated pair transition above the nuclear Fermi surface. They further showed that SRCs come predominantly in the form of neutron-proton (np) pairs owing to a strong short-ranged Tensor interaction. In neutron-rich nuclei, this np-SRC dominance keeps the fraction of high-momentum neutrons constant, while increasing the proton fraction. This suggest that, in contrast to many textbook images, protons in neutron-rich systems have higher average kinetic energy than neutrons. Examining the finer details of the isospin structure of SRC pairs, Hen and colleagues discovered an increase in the fractional abundance of pp-SRC pairs with increasing pair relative momenta, providing the first direct mapping of the tensor-attraction to scalar-repulsion transition in the NN interaction at very short distances. 
Examining the parton structure of nuclei, Hen is a leading investigator of the nuclear EMC effect. Reporting on the first observation of a linear correlation between the abundance of SRC pairs in nuclei and the strength of the EMC effect, hen is leading the development of a class of SRC based models of the EMC effect. By using high-precision measurements of both SRC abundances and of the EMC in heavy neutron-rich nuclei, they further showed that the EMC effect in all nuclei can be explained by a single universal modification function of the structure of nucleons in SRC pairs, extracted this function via a global analysis of world data and used it to predict the free neutron structure function and constrain SU(6) symmetry-breaking mechanisms in QCD.
Electron-Ion Collider:
Most recently Hen has joined the effort to construct a U.S.-based Electron-Ion Collider (EIC) at Brookhaven National Laboratory. Following work on the EIC Yellow-Report, Hen co-led the EIC Comprehensive Chromodynamics Experiment (ECCE) consortium of 98 institutions that developed a reference design for the first EIC detector. Following the selection of the ECCE design, Hen co-led the establishment of the wider ePIC collaboration that includes over 600 collaborators from over 160 institutions around the works, working to design and build the EIC detector. In 2023 Hen was elected to chair the EIC Users Group that includes over 1400 scientists from around the world.
Neutrino Interactions and Oscillations:
In addition to Hen's work on SRCs, the EMC effect and the development of the EIC, Hen works in the field of neutrino interaction measurements for precision neutrino oscillation physics. Hen is a member of the MicroBooNE collaboration and co-founded the Electrons-for-neutrinos collaboration where he helps to enable the precision study of neutrino oscillations by performing high-precision measurements of neutrino-nucleus and electron-nucleus interactions and works on their consistent modeling for experimental oscillations analysis.
===Fellowships and awards===
* 2022 American Physical Society Fellow
* 2021 Class of 1956 CD Professorship Chair
* 2020 Alfred P. Sloan Research Fellow Fellow
* 2019 Science APS Stuart J. Freedman Award in Experimental Nuclear Physics.
* 2019 U.S. DOE Office of Science Early Career Scientist and Engineer Award.
* 2019 IUPAP Young Scientist Prize in Nuclear Physics.
* 2018 Guido Altarelli award.
* 2018 Amar G. Bose Fellowship.
* 2016 Fermi Lab Intensity-Frontier fellowship.
* 2016 Jefferson Science Association dissertation prize.
* 2015 MIT Pappalardo Fellowship.
* 2015 Israeli Physics Society dissertation.
* 2013 A. Pazi Award of the Israeli Council for Higher Education.
* 2011 Tel-Aviv University Y. Eisenberg Prize for graduate research.
Category:Israeli people
Category:People from Jerusalem
Category:Tel Aviv University alumni
Category:Hebrew University of Jerusalem alumni
Category:Professors