End of an Era
May 9, 2012


On May 18, we will stop operations of CEBAF, our Continuous Electron Beam Accelerator Facility, marking the end of our FY12 operations. As we anticipated, there were many technical challenges associated with the running this year. These included bringing the accelerator to good performance after making major changes during the 2011 six-month shutdown. The demands on the beam, especially from the Q-weak experiment, were very challenging, but 180 microamps with spin flipped at 960 Hz became the norm.

As an experiment, Q-weak had faced most of its technical challenges during 2010 and 2011, but the other experiments g2p/GEp and HDice also demanded a high degree of technical sophistication. HDice relies on frozen spin polarization of both the hydrogen and the deuterium in the target, thus providing access to polarized neutrons. In the main, while not every goal was reached, the run was good. If you have been a student of the experimental physics schedule, you will know that this was the fourth and final year of a schedule, which was laid out in late 2008. That schedule was intended to complete the program of physics measurements needing the 6 GeV CEBAF. While very ambitious, we have been successful.

So, May 18, will also be the end of an era.

When the choices were made in the late eighties to build the 4 GeV electron accelerator here in Newport News, it was meant to be revolutionary. It was to outstrip the existing nuclear physics facilities in energy, to outstrip the existing electron accelerators in duty factor, to outstrip the muon scattering facilities in intensity and to outstrip all of them in terms of the spin control. The culmination of the current program is reached with all of those goals achieved, and indeed in energy, the machine has operated consistently at 6 GeV, exceeding the initial goals. And few foresaw operation with the exquisite control we now call "parity quality beam." The physics achievements with the exception of the most recent results were celebrated in the publication "New Insights into the Structure of Matter: The First Decade of Science at Jefferson Lab."

As a relative newcomer to the laboratory, this " End of an Era" is an opportunity to pay homage to the community, lab staff and user scientists whose desire to excel and whose desire to understand the nucleus and the nucleon led to such an impact on our knowledge.

What is especially beautiful is that during the first decade of operations, the opportunities to expand the scope of our physics were recognized and the plans for the upgrade to 12 GeV were developed. In 2008, we were given approval to start construction. In the three and a half years since then, we have received substantial funding and a considerable amount of civil construction has occurred. We have a new Hall D, and a Tagger area where the photon beam for Hall D will be produced. We have refurbished some of the magnet arcs in the machine during 2011 and we took delivery of large objects such as the Cold Box for the extension of the Central Helium Liquefier. With the accelerator shut down, we will be able to continue and complete the transformation of the machine to 12 GeV. In Fall 2013, we hope to begin commissioning the renewed machine.

So, this is the end of one era, but May 18, 2012 will also mark the beginning of the transition to an exciting new era.

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