Jefferson Lab > Physics > Program Advisory Committee
Privacy and Security Notice

Program Advisory Committee (PAC)


October 31, 2006

Dear Jefferson Lab User,

The Jefferson Laboratory Program Advisory Committee (PAC 31) will consider new proposals, updates, and letters-of-intent for experiments using presently available beams during the week that begins January 29, 2007. Proposals for PAC 31 are due at Jefferson Lab by the close of business on Monday, December 11, 2006. PAC 31 will also review the schedule for experiments in the three halls. As is the established tradition, the JLab Technical Advisory Committee (TAC) will make comments on the technical viability of the proposals and provide these comments to the spokespersons and the PAC prior to the meeting. As always, proposals will be judged on the quality of the physics, technical feasibility, and the ability of the group to carry out the proposed measurements.

Planning for the 12 GeV Upgrade continues to progress. PAC30 was the first PAC to review formal proposals for science with the Upgrade. For the next few years we anticipate that "12 GeV" PACs will alternate with "6 GeV" PACs. As the project progresses and the formal schedule for the various Critical Decisions develops, we will work with both DOE and the UGBOD to plan the transition from 6 GeV running to 12 GeV construction and running. Roughly three years before the shutdown of the accelerator for the installation and commissioning of 12 GeV hardware, we will present the PAC with a plan for the last three years of 6 GeV running for their advice, and stop accepting proposals for running prior to the Upgrade. With the PAC advice in hand, a draft schedule (subject of course to the details of year-by-year funding) will be published and there will be no jeopardy reviews for the planned set of experiments. Future running with lower energy beams will have to compete with other uses of the beams available from the Upgrade.

In considering beamtime allocations for PAC 31, we note that all three Halls are close to the equilibrium backlog goal, so the total beamtime available for distribution to them at PAC 31 will be the nominal hall allocation of the equilibrium rate. The equilibrium rate corresponds to about three months of running in Halls A and B in each six month period, or about 1½ months (or 45 days) of 100% efficient operation. In Hall C we typically run less (~35 PAC days during each six month period) due to the setup times associated with major installation experiments. This leads to a PAC allocation of 45 days in Halls A and B, and 35 days in Hall C plus the sum of the previously-approved time for all of the experiments undergoing jeopardy review at the PAC. (The ideal backlog would "ramp" between 4 years just after a PAC meeting down to 3½ years just before a PAC meeting, as the program progresses). Conditionally approved experiments have been included in the sum. For purposes of assigning the PAC beamtime allocation we consider two cases for conditionally approved experiments: if the PAC assigned beamtime to a conditionally approved experiment, that allocation will be used; if the PAC has not yet allocated beamtime, a conditionally approved experiment will be assigned a beamtime of 22 days for purposes of this calculation (the average for all approved experiments).

In all cases, this guidance will not be so rigid as to preclude PAC consideration and recommendation of important new experiments and/or programs that cannot be accommodated within the nominal beam time limits, but any such exceptions will have to present a compelling scientific case.


The laboratory has a three-year Jeopardy Rule that was devised both to reduce the beamtime backlog and to ensure that the ratings of all approved experiments continue to accurately reflect their scientific priority. Jeopardy begins three years after a proposal is approved. Previously approved experiments that have not yet been run or scheduled must return to the PAC for a review of their status. The jeopardy review recognizes the fact that the scientific world doesn't stand still: theoretical developments and experiments elsewhere can affect the scientific interest in experiments here, and therefore their priority. It reinforces our goal of always identifying and running the best possible science program. Jeopardy also provides a fair and equitable mechanism to reduce the backlog of approved experiments to about three years, as recommended by the Users Group Board of Directors, the PAC, and the laboratory's Science and Technology Review Committee. All PACs consider both new proposals and resubmitted "jeopardy" proposals on an equal footing.

In preparing for a jeopardy review, approved proposals for single experiments can submit either a revised, complete proposal, or a brief update to the approved proposal. If you are submitting a revised, complete proposal, it must conform to the standard requirements for new proposals to the PAC (see below). An update must:

If you are submitting an update and want the User Liaison Office to attach a copy of the original proposal to the material that is submitted to the PAC for review, please indicate so clearly in your submission.

For run groups in Hall B involving many experiments, the jeopardy update and review may (at the discretion of the spokespersons) be simplified to include only three main items:

During the jeopardy review, the run groups can request:

Starting with PAC 23 (and therefore for this PAC as well) all time associated with experiments up for jeopardy review in a hall will be included in the PAC's time allocation for that hall. Therefore, the total beamtime allocation given to PAC 31 for a hall will be equal to the "basic allocation" identified above (which depends on how close to equilibrium the backlog is in the hall) plus all of the sum of the previously approved time for experiments undergoing jeopardy review. Conditionally approved experiments will be included in the jeopardy sum. For purposes of assigning the PAC beamtime allocation we consider two cases for conditionally approved experiments: if the PAC assigned beamtime to a conditionally approved experiment, that allocation will be used; if the PAC has not yet allocated beamtime, a conditionally approved experiment will be assigned a beamtime of 22 days for purposes of this calculation (the average for all approved experiments). In the future, if the backlog in a hall falls below the backlog target, then we will augment that hall's PAC allocation by half the number of days the backlog is below the target.

We continue to work hard to improve the accelerator and hall operating availabilities in order to provide more useful beam time each year. This is one of the primary goals of both the Accelerator Operations group and the hall groups. We have requested incremental funding from DOE in support of this effort, and we have also asked DOE for the additional funding necessary to increase accelerator operations so that we can deliver more physics each year. Discussions on these issues are ongoing.


New Proposals

New proposals requiring beam energies up to 6 GeV will be reviewed by PAC 31. It is highly recommended that you consider the following when preparing your proposal:

  1. Be careful to submit a complete package that can stand alone. Do not assume that the PAC is aware of information contained in previous proposals, technical notes, and letters of intent. If this information is important background for your proposal, be sure that you include it in the proposal, for example as an appendix.
  2. Give justification for the uncertainty of the final results. Give realistic estimates of uncertainties in resolution, absolute momentum and angle calibrations, random coincidences rates, etc. and indicate how these impact the final results.
  3. Be sure to include a detailed table showing how you calculated the number of days requested. Since run time is a very scarce resource, the PAC reviews very carefully the details of the request, makes its own calculation, and allocates the time accordingly. Therefore it is essential to give a full and detailed justification of your request.
  4. Include experimental details and simulations. Complex and challenging experiments often require extensive justification and simulation calculations. Requests for large commitments of Laboratory resources require a more detailed justification than more straight forward projects. Discussions of yield, backgrounds, and projected statistical and systematic errors, are essential elements in the justification. To support these, it is important to give the results of simulation calculations that should be the basis of the experimental design. This is an essential component of the package required in order to get such proposals approved.
  5. Indicate how the project relates to other approved proposals. The PAC and the Laboratory have specifically asked proponents of new proposals to clearly state how their experimental goals are addressed by other approved experiments at the Laboratory. As stated in earlier PAC reports, failure to pay sufficient attention to this charge can result in the PAC not considering the new proposal until the information is provided.

Experiments with Similar Physics Goals

On your proposal cover sheet indicate any existing approved, conditionally approved, or deferred experiments that have physics goals similar to those in your proposal. In the text of your proposal, compare and contrast your proposal with respect to these proposals and experiments already considered or under consideration by previous PACs. Note that both one-page summaries and the full text for most proposals are available on-line at You may also contact User Liaison (see below) for copies of proposals.

The spokespersons for the experiments and proposals you have listed on your proposal cover sheet will receive copies of your proposal prior to the PAC meeting. They will be allowed to submit written comments that will then be passed on to the PAC with a copy provided to you. If you fail to identify a previously approved proposal with similar physics goals, the spokesperson for the previously approved proposal may request that final approval of your proposal be contingent on review by a subsequent PAC of the issues they want raised. If laboratory management agrees that the request has merit, the final approval of your proposal will be deferred until the following PAC has reviewed the situation.

Experiment Summaries

A summary of all approved and conditionally approved experiments can be found on line at: PAC reports can be found on line at:

Beam Time

The beam time request should be provided in some detail using the standard forms identified below. Do not request any contingency time as the scheduling process includes this time. The beam requirements and time request should include all of the time for the following activities: setup & installation; alignment; calibration; check out and testing without beam; commissioning with beam; physics measurements (list all currents, energies, targets target and experimental apparatus configuration changes, and [for Halls A and C] spectrometer angle changes); and decommissioning.


If your collaboration has an approved experiment, a conditionally approved experiment, or a deferred proposal and you would like to modify the physics goals, significantly change your running conditions, receive reconsideration of your scientific rating, or achieve full approval for a conditionally approved or deferred experiment, please submit an update. When an update is submitted, the PAC allocation for the relevant hall will be increased by the full previously-approved beam time for the experiment requesting the change, and then the update request will be considered on an equal footing with all new proposals and all jeopardy proposals submitted to that PAC. That is to say, in submitting an update requesting a change in a previously approved experiment, all of the previously approved beam time will be at risk. Note that this risk may be avoided by submitting a new proposal requesting time for additional physics measurements beyond those in the previously approved experiment, but the PAC review of the new proposal will have no effect on the PAC rating of the previously approved experiment. Note also that the PAC may or may not choose to hear an oral presentation for updates depending on the scope of the proposed changes. The PAC beamtime allocation for cases involving update proposals will be treated in the same manner as is the case for jeopardy proposals.

Deferred Experiments

Deferred experiments must be updated within one year or they will be removed from future consideration.

Withdrawn Proposals

A category of "withdrawn" has been established for proposals that were approved by a previous PAC but haven't been run within three years of approval and whose authors chose to withdraw the proposal rather than defend it at a jeopardy review. Withdrawn proposals shall be considered part of the public domain, and by withdrawing the proposal the authors have given up any "intellectual property rights" they have to the physics it covers. Any interested party, including the original authors may submit a new proposal covering the same physics to a future PAC.

Rejected Proposals

A proposal based on a previously rejected proposal is considered a "new" proposal. Further, this `new' proposal must include substantive changes that fully address the issues raised by the PAC that rejected it for it to be considered by the new PAC.


Letters-of-intent may be submitted to solicit the evaluation by the PAC of a new line of research before investing the large effort required to prepare a full proposal. In general, the letters-of-intent will involve either a major new experimental apparatus or extension of present beam properties. Letters-of-intent will be made public after receiving PAC appraisal in the same manner as full proposals. This means that the research program contained in them would enter the public domain; therefore, the letters-of-intent mechanism cannot be viewed as a means of "staking out territory." Rather, it provides experimenters with feedback at an early stage on the PAC's views on the scientific and technical merit of an idea that the experimenters intend to develop into a full proposal.

Due Date: New Proposals, Updates, and Letters-of-Intent

Proposals, Updates, and Letters-of-Intent for PAC 31 are due at the JLab User Liaison office by close of business Monday, December 11, 2006.

Jefferson Lab
User Liaison Office, MS 12H
12000 Jefferson Avenue
Newport News, Virginia 23606


All submissions can be mailed or submitted electronically, electronic submissions are preferred. An electronic version must accompany all hard copies. Fax submissions are not acceptable.

All proposals and updates to be considered by PAC 31 must also include a completed:

These forms are available at the url:


For all proposals and updates, copies will be made in B&W. If color copies are preferred, provide 32 copies with your original.

Procedures for Experiments

Procedures for experiments are provided at The procedures include the submission and re-submission of proposals, the PAC's scientific ratings and recommendations of Approval, Conditional Approval, Deferral or rejection, the Directors award of beam-time, the experiment preparation and scheduling processes, the associated Environment, Health and Safety reviews, the running of the experiments, the allocation of computational resources, and the publication of results including presentations at conferences.

Reference Material Hard Copies

If you would like any of the materials on the Web sent to you, please contact User Liaison via phone (757-269-6388), fax (757-269-6134) or e-mail (