Jen-Chieh Peng



Jen-Chieh Peng

Primary Research Area

  • Nuclear Physics
409 Loomis Laboratory


Professor Peng received his bachelor's degree in physics from Tunghai University in Taiwan in 1970 and his Ph.D. in nuclear physics from the University of Pittsburgh in 1975. He worked as a researcher at the Centre d'Etudes Nucleaires de Saclay and the University of Pittsburgh before joining the Physics Division of Los Alamos National Laboratory in 1978. He became a Laboratory Fellow at Los Alamos in 1996. Professor Peng joined the Department of Physics at the University of Illinois in February 2002.

At Los Alamos, Professor Peng made pioneering contributions to several areas of medium energy physics. He was the first to recognize the feasibility of producing η mesons at the Los Alamos Meson Physics Facility (LAMPF) and made the first (π,η) measurements on nuclei. In the early 1980s, Professor Peng proposed the (π+,K+) measurements at Brookhaven National Laboratory's Alternating Gradient Synchrotron (AGS) accelerator, which ultimately identified single-particle states of lambda hypernuclei. Since the late 1980s, Professor Peng has made seminal contributions to high-energy nuclear physics in a series of experiments at Fermilab (E772, E789, and E906), which pioneered the use of massive lepton pair production to probe the distributions of antiquarks in the nucleons and nuclei. Professor Peng was the spokesperson or co-spokesperson for ten experiments carried out at various laboratories.

More recently, Professor Peng initiated a program at the Jefferson Laboratory to measure the novel transverse momentum dependent parton distribution. His group at UIUC also demonstrated the feasibility of the dressed-spin technique for a future experiment to search for neutron electric dipole moment. He has been actively involved in the Daya Bay neutrino oscillation experiment which discovered the neutrino mixing angle θ13 in 2012. Professor Peng is a Fellow of the Amercian Physical Society.

Research Statement

Daya Bay Neutrino Experiment

The UIUC group has been a member of the Daya Bay Collaboration since the experiment was proposed in 2006. Using eight identically designed 20-ton detectors located at three underground experimental halls, antineutrinos from three pairs of reactor cores are detected. The UIUC group contributed to the R&D, testing, and commissioning of the Daya Bay PMT system. In March 2012, the Daya Bay experiment observed clear neutrino oscillation signals and announced the discovery of the neutrino mixing angle θ13. The UIUC group has made significant contributions to the precise extraction of the mixing angle θ13 and the mass-squared difference, |Δ m2|. It has also led the effort to search for light sterile neutrinos. The Daya Bay experiment will continue to take data until the end of 2017.

SeaQuest Experiment at Fermilab

The SeaQuest experiment at Fermilab measures high-mass dileptons to explore the antiquark structure of the nucleon and nuclei via the Drell-Yan process. The 120 GeV proton beam from the Main Injectorat Fermilab and a newly constructed dilepton spectrometer are utilized for this experiment. The major physics goals of the SeaQuest experiment include the investigation of the flavor asymmetry of the antiquarks in the proton, and the modification of antiquarks in the nuclei. SeaQuest started data-taking in early 2014, and will continue until summer of 2017.

Research Honors

  • Yu-Shan Scholar, Ministry of Education, Taiwan, 2020
  • Distinguished Alumni, Tunghai University, 2020
  • Breakthrough Prize, 2016
  • Distinguished Visiting Fellow, Academia Sinica, 2015
  • Fellow, Japan Society for the Promotion of Science, 2000
  • Fellow, Los Alamos National Laboratory, 1996
  • Fellow, American Physical Society, 1993

Semesters Ranked Excellent Teacher by Students

Spring 2013PHYS 575
Fall 2008PHYS 570

Selected Articles in Journals

Related news

  • Research

Now a group of physicists in the U.S., Japan, and Taiwan have shed new light on the asymmetry in the makeup of the proton sea. The scientists are members of a decade-long experiment called the SeaQuest Collaboration, conducted at the Fermi National Accelerator Laboratory (Fermilab) near Chicago, including University of Illinois at Urbana-Champaign Physics Professors Naomi Makins and Jen-Chieh Peng and their postdoctoral researchers and graduate students, who participated in all phases of the experiment since its inception.

  • Research

Do sterile neutrinos—hypothetical particles that do not interact with matter except through gravity—really exist? If so, this would solve some of today’s major mysteries in particle physics and cosmology. For two decades, researchers around the globe have sought evidence that would prove or disprove the reality of sterile neutrinos, with inconclusive outcomes.

Now, a new result has all but ruled out the possible existence of a light sterile neutrino in a regime suggested by an earlier experiment. Researchers from two major international collaborations—the Main Injector Neutrinos Oscillation Search (MINOS) at Fermi National Laboratory and the Daya Bay Reactor Neutrino Experiment in the south of China—joined forces, each contributing years of data that, taken together, paint a nearly complete picture. The joint result published in Physical Review Letters has significantly shrunk the hiding space for a light sterile neutrino.