Planning for the APS Upgrade Makes Major Progress

There was an air of excitement at an APS Upgrade summary planning workshop held at Argonne on August 10th and 11th. Encouraged by our sponsor, the Department of Energy's Office of Basic Energy Sciences, we presented users with a wide menu of options for upgrades to the APS. In addition to proposals for storage ring upgrades--from lower emittance lattices to added ID ports--we introduced the concept of upgrading the APS to an energy recovery LINAC (ERL). The ERL option generated particular excitement from the participants because it not only promises revolutionary performance improvements but also retains compatibility with the existing beamlines and offers an upgrade path without extended disruption to user operations. Several of the scientific workshop organizers, particularly those involved in ultra-fast science and imaging/nanoscience, were very enthusiastic about the potential for revolutionary capabilities offered by an ERL. You can find many of the presentations at our upgrade web site (

To help determine the upgrade options that best merit further consideration, we will assemble a machine advisory committee (MAC) of top international experts for a meeting late this year. We will developed feasible options in detail and present them to the MAC. For each option, the MAC will be asked to advise:

  • Can it deliver the technical performance claimed?
  • Is the claimed performance technically revolutionary, and how does it compare with "green-field" proposals?
  • What are the technical R&D challenges needed to successfully deliver the upgrade?
  • What is the expected disruption to users associated with implementing this option, and what can be done to mitigate risk?
  • Are there other proposals that should be considered?

We encourage our users to engage closely in planning for the upgrade and assure them that their voices are being heard. User input has already had major impact on our direction, for example, by stimulating the emergence of a serious ERL option.

We will share each step with the user community as we flesh out our options and post up-to-date information on our upgrade web site. Once we have received input from the MAC, we plan to work in unison with the user community and our Scientific Advisory Committee to move forward quickly early next year in selecting the most favored machine approach for further development into a scientific proposal.

The proposal will succeed only if the revolutionary technical performance we seek can be shown to pay off in ground-breaking science, and for this evaluation we rely on our users to make their case and state their desires. We fully expect that the upgrade will include coupled major innovations for many beamlines--insertion devices, optics, detectors and software--to position us for truly revolutionary experiments. Questions or comments can be directed to APS Deputy Directors Denny Mills ( for x-ray science, or Rod Gerig ( for accelerators, or to myself, Murray Gibson (

We will not wait for the upgrade project funding to begin research for the future. Resources permitting, we will upgrade beamlines and insertion devices (see item 2) to till new scientific ground. An important example presented at the summary meeting is a room-temperature RF crab cavity approach for pulse chirping on a single sector of the APS; we hope to implement this upgrade within a year. This change will provide a bridge to the ultra-fast science that will be made possible by the upgrade. More information on the picosecond pulse capability, is available from John Carwardine (

Murray Gibson