by John Harris. Published: 16 October 2011

The Undersecretary for Science for the U.S. Department of Energy (DOE), Dr. Steven Koonin, paid a visit to CERN on 14 – 15 September. In addition to many other activities at CERN, Dr. Koonin toured ALICE and spoke with various ALICE members at Point 2. In the photograph, taken in front of the ALICE building with life-size photograph of the detector cross-section, Dr. Koonin can be seen in the centre, with Rudiger Voss, CERN adviser for the US, ALICE Collaboration spokesperson Paolo Giubellino and others including several ALICE members from US Institutes.


"Family" photograph of ALICE members with Undersecretary for Science for the U.S. Department of Energy, Dr. Steven Koonin,
in front of the ALICE building.

Dr. Koonin is a theoretical physicist who was on the Faculty at the California Institute of Technology from 1979 to 2006. He served as Provost at Cal Tech for nine years and moved to British Petroleum as their Chief Scientist from 2006 - 2009. He has served in his present role in the DOE since being confirmed by the US Congress in early 2009. Dr. Koonin is well known for his theory work in many-body physics and astrophysics. He is known to our field for his theoretical work in heavy-ion physics on two-particle (Bose-Einstein) correlations during the field’s infancy1. He introduced what has become known as the Yano-Koonin-Podgoretskii (YKP) parameterization of the pion source created in high-energy heavy-ion collisions. The YKP parameterization factorizes the expanding source in terms of its longitudinal and transverse spatial and the temporal extensions (lengths of homogeneity), in the co-moving frame of the emitting source element. This approach is used today and can be seen in recent ALICE publications on the source size and lifetime in Pb-Pb collisions at the LHC.

More photographs from Koonin's visit and meeting with ALICE physicists can be found at

  • 1. F. Yano and S. Koonin, Phys. Lett. 78B, 556 (1978).