The ATLAS Program Advisory Committee (PAC)

Since ATLAS is a National User Facility and available for experiments to anyone in the world, all experiments to be performed at ATLAS must be reviewed and approved by the ATLAS PAC. The PAC consists of 5-7 internationally recognized nuclear physicists, most of whom come from outside Argonne. The PAC members are appointed by the Scientific Director of ATLAS and typically serve for a term of two years. The PAC normally meets twice per year.

At roughly two months prior to a PAC meeting, a call for proposals is issued by e-mail to the list of all ATLAS Users. The due date for proposal submission is normally about one month before the PAC meeting. The proposal submission process is done electronically via the web and e-mail, although hardcopy submissions through surface mail will be accepted.

Once the proposals have been received, copies are distributed to all PAC members, to ATLAS Operations personnel, and to various experimental instrument specialists in the Physics Division. The PAC members will review each proposal for scientific merit and technical feasibility. Consideration is also given to the manpower and publication "track record" of the collaboration proposing the experiment. The in-house personnel will review the proposed experiments for beam production issues, compatibility with existing experimental equipment, and safety related issues. This information is then provided to the PAC members in the form of a summary sheet and any additional comments. The PAC members may ask the Principal Investigator (PI) on the proposal for additional information or clarification of questions.

At the PAC meeting, the members consider and discuss each proposal in detail. The PAC then ranks the set of proposals and provides advice to the Scientific Director of ATLAS on the priority of each experiment and the number of days of beam time to be allocated to the approved experiments. They may also request that the PI provide more information or satisfy other requirements before the experiment can run. For those experiments that are not approved, the PAC may provide suggestions to the PI on how to improve the proposal should they want to re-submit it at the next call for proposals. Historically the PAC has approved about 50% of the proposed experiments, depending on the level of demand for beam time.

If you would like additional information about becoming an ATLAS User, please contact Ms. Barbara Weller in the Physics Division of Argonne National Laboratory at (630) 252-4044 or via email at:


Users performing basic research experiments at ATLAS are not charged for beam time. The ATLAS facility normally provides isotopic beams at no expense to the User. There is also a state-of-the-art target making facility in the Physics Division. Furthermore, technical assistance with detection equipment and beam line setup may be obtained from the Physics Support Group. Finally, Users are welcome to collaborate with the in-house staff on experiments of mutual interest.