Physics Advisory Committee
November 5-7, 1999
General Comments and Recommendations
This PAC meeting is the first since Michael Witherell has taken over as Director of the Laboratory. The last four months have been a period of many changes and much activity, as the Laboratory has worked to guide and review the preparations for Collider Run II as well as to plan for other new projects. After hearing a detailed review of developments in the Run II schedule and detector preparations, the Committee was asked to make recommendations on two new proposals, to consider Stage II approval for two upgrade projects, and to comment on several other ongoing projects.
It was reported to the PAC during this meeting that our colleague Marty Breidenbach, who served on the PAC from June 1995 through June 1999, has been selected as the recipient of the Panofsky Prize in 2000. The members of the PAC are delighted by the news, and congratulate Marty on this well-deserved honor.
The Laboratory presented to the Committee a new long-range schedule for the completion of the detector and accelerator upgrade projects. The Committee notes significant slippage in the start date of Run II of almost a year during the past year. While the final date is dismaying, because we are all eager to see physics from Run II, the process used to devise the schedule is encouraging. The Laboratory and the collaborations worked together to understand all subprojects, from the bottom up. Because of this, and because the upgrades are moving into a production phase, this schedule should be more realistic than the schedules published in the past. Moreover, the exercise of developing a realistic schedule has opened communication channels within the collaborations, which will be essential for keeping the schedule.
In the new schedule, Run II starts on March 1, 2001. The CDF and D0 spokespersons and project managers expressed their commitment to meeting this date. For example, as suggested by their respective Lehman reviews earlier this week, each collaboration will develop fallback plans, including descoping scenarios, to prevent further delays. The Committee feels encouraged by such resolve. Vigorous action from managers and collaborators over the next several months is crucial. The Committee notes that the collaborations have already begun to react to the new schedule and the need to keep it.
The Laboratory has increased the financial and human resources available to the collider collaborations. The Committee endorses this action because Run II remains the highest priority, but recognizes the consequences. Funding for all parts of the Laboratory will be seriously affected, including high priority activities such as NuMI/MINOS, MiniBooNE, and R&D for future accelerators. The Committee emphasizes that this revised schedule absolutely must be adhered to, without fail, to avoid further jeopardizing not only Run II but also the rest of the Laboratory program.
The Committee heard reports from CDF and D0 on the status of the detector upgrade projects. CDF expects to be ready for a 2.5 month Commissioning Run, with a minimal silicon system, starting in mid-August, 2000, and to be ready for collisions with the complete detector on March 1, 2001. The critical path for CDF is currently set by two systems. For the Commissioning Run, the Central Outer Tracker (COT) is the item of most concern. The COT suffered a delay of five months during the summer, due to the need to correct a number of problems which were found after stringing was completed. For Run II itself, the silicon detector system is on the critical path. CDF projects that all sensors will be delivered by May, 2000, based on current delivery rates from Micron. The SVX3 chips and hybrids are less of a schedule concern. The projected date for completion of the silicon system is mid-November, 2000.
D0 expects to be ready for collisions on February 2, 2001. The most important concerns for D0 are the production of silicon detectors and the Fiber Tracker. While the timely delivery of silicon sensors is less of an issue, the rate of assembly of the ladders is now driving the schedule. There are currently problems with the production yield of good detector modules, which if not improved would imperil the scheduled completion in mid-September of the silicon detector. As for the Fiber Tracker, one cylinder has now been completed, but alignment problems have been found which the collaboration has been unable to fix completely. A decision has been made to accept tolerances of 3 mil rather than 1 mil. While this compromise complicates the trigger, the considerations of the schedule make it a necessary tradeoff. The Committee believes that this is an example of the sort of difficult decision that will be needed in the future, from both collaborations, to hold firmly to the new schedule.
The Committee would like to express
its support for the Laboratory's new initiatives in accelerator R&D.
1. The Committee is pleased with the appointment of the new Accelerator Advisory Committee, which includes many of the leading figures in advanced accelerator research.
2. The collaboration with SLAC on NLC seems to be beginning well. The Committee is especially pleased that the Fermilab group is taking leadership of specific systems for which it has unique expertise.
3. The Committee is pleased by the decision of the Neutrino Factory and Muon Collider group to concentrate on the design of a 50 GeV neutrino source. The consideration of a complete and potentially useful system with modest design objectives has brought this group needed focus.
4. The Committee is pleased that Fermilab
is working to retain its leadership in the technology of high-field superconducting
The Committee heard an update on the status of BTeV detector R&D. The BTeV collaboration appears to be focussing on many of the key issues, and the Committee looks forward to the submission of a detailed proposal in the future.
The Committee was presented with a status report from the MiniBooNE Collaboration. A number of goals have already been met, and satisfactory progress is being made in almost all areas. The collaboration has developed and optimized the horn design, and has achieved the focussing needed for MiniBooNE physics with a single-horn system. This new horn design results in a smaller high-energy tail and therefore a reduced po background. Civil construction of the detector hall has begun, most of the phototubes are in hand, and a prototype of the phototube support structure has been built. The collaboration is on schedule for, and is committed to, a goal of beginning data-taking by the end of 2001. The Committee commends them for the progress achieved so far.
Further work is needed on Booster upgrades to achieve the higher intensity needed for MiniBooNE, and especially for combined Collider/MINOS/MiniBooNE running. In order to achieve this, the Booster must operate above 7.5 Hz, and beam losses must be reduced by an order of magnitude.
Although much has been accomplished in the last year, the Booster remains a matter of concern both for MiniBooNE and for the whole experimental program. The Laboratory will devote the needed resources to this problem during the next two years. The Committee would like to have an update on progress at the next PAC meeting in April 2000.
The Committee recommended that Stage II approval be granted to the following collider upgrade projects: P-908 - D0 Silicon Track Trigger, and P-909 - CDF Time-of-Flight.
The Committee considered two new proposals: P-915 - R&D for a Hybrid Emulsion Detector for MINOS, and P-916 - CDF Forward Detector.
For P-915, the MINOS collaboration has requested R&D support for a hybrid-emulsion detector to be built in the MINOS cavern in front of the MINOS baseline detector.
The Committee concluded, after extended discussion of the proposal, that the emulsion method has not been shown to lead to a compelling experiment. Therefore the case for R&D to improve its practicality is not strong enough to justify the Laboratory's investment.
The Committee notes that the MINOS experiment is entering a new phase. Construction is underway, with all of the excitement and effort that involves. At the same time, the Laboratory's commitment to the new Run II schedule has placed extraordinary stress on all other activity, MINOS included. Meeting the schedule for detector construction and commissioning will require a high degree of focus from the MINOS collaboration on the baseline detector over the next few years.
The Committee heard a presentation of proposal P-916, entitled "Further Studies in Hard Diffraction and Very Forward Physics," from the CDF collaboration. The studies of hard diffraction and rapidity gaps using the proposed detector would provide an interesting extension to the physics capabilities of the CDF detector and complement nicely the program of diffraction studies at D0. Continuous coverage in rapidity out to |h| of 7.5 is a particular strength of the proposal.
The Committee recommends that the beam shower counters and the forward pot detectors be installed before the start of Run II as proposed. The Committee notes that beam loss monitors would be needed in any case and concludes that installation of these detectors will have minimal impact on the baseline upgrade.
However, due to the schedule slippage
of the baseline detector, the Committee is concerned about adding additional
scope to the experiment. The Committee recommends deferral of consideration
of Stage I approval on the miniplug detectors until the June 2000 PAC meeting
when the rate of progress on the baseline upgrade will be better understood.