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Dear members of the LHCC and Research Board:
We, the members of the FELIX Collaboration, write to you about the recent sequence of actions regarding the FELIX Letter of Intent (LOI). We believe that they were taken in a precipitate way, with gross violation of due process. In particular, there has been no thorough scientific review. Our primary grievance is that the LHCC referees never contacted the proponents before arriving at its negative conclusion, nor were the proponents permitted to directly present the initiative in person to the committee. Important issues, including possible staging scenarios to reduce cost, and ongoing efforts to build collaboration strength, were thus never presented to the committees.
The justification of your decision which has been presented by your committees and by the Director General clearly has to do with costs: CERN is under great financial stress, and the issue of affordability is of course a very real one, an issue not unnoticed by the collaboration. And it is clear that the FELIX collaboration as presently constituted is far from being able to provide the resources--so far in the eyes of the laboratory that it sees no point in even listening in detail to the physics case or the technical issues involved in the provision of a potential fifth site for collisions at the LHC. Instead, the Director General and the chair of the LHCC expressed shock that a collaboration with so few identifiable sources of funds should have the audacity to suggest that CERN should consider--consider, not implement-- the program the collaboration has laid out. Indeed, after more than a year of apparent encouragement by CERN management to create the LOI, the response now is as if the collaboration has betrayed the laboratory by not finding the funds before working out and presenting the ideas.
When we asked the chair of our referees, Donald Hartill, why he went into the LHCC meeting with a negative opinion of the LOI (without the need for consultation with the proponents), he replied that the standards for an LOI nowadays had gone very high and that the FELIX document did not meet the standards. In fact, we believe that the FELIX LOI stands up favorably, in terms of laying out the physics case and of technical detail, with the LOI's of other larger LHC initiatives.
We would like to emphasize that the creation of the FELIX LOI involved a large number of people doing a lot of work. The history of how this came about is as follows:
In November 1994, in an LHCC workshop on ``Further Physics Topics", Bjorken and Eggert gave presentations about full-acceptance physics, following the line set by Bjorken at the SSC. In particular, the value of pA collisions was stressed at that time, and this discussion helped lead to the decision in the summer of 1995 to have separate RF for each beam. This in turn led to the availability of I4 for collisions and a fifth experiment. In February of 1995 (CERN/LHCC 95-03) the LHCC provided some encouragement of the physics with its statement that
The LHCC noted the interest in diffraction, and expects that such studies may also form part of the LHC experimental programme. The committee encourages interested parties to work together on an integrated approach towards this physics, whilst bearing in mind the LHC physics priorities already established.
At this time, efforts were made to implement the program into the ALICE detector. But after ALICE decided to incorporate forward muon detectors, it became increasingly impractical. The other experiments were also not appropriate, either because of the intrusion of low-beta quads or, in the case of LHC-B, the asymmetric location of the crossing point. So, with I4 in principle available for collisions, attention was focused on that option. It eventually evolved into the FELIX design.
In June 1996 the LHCC (CERN/LHCC 96-28) added to the above statement that
The LHCC urges that any new experimental initiative should be consistent with the restricted resources likely to be available, and combined as far as possible with one of the foreseen experiments.
The second part of this constraint, for the above reasons, is incommensurate with the FELIX physics goals: even with additional hardware, the ``foreseen" experiments cannot carry out the bulk of the FELIX agenda without seriously compromising their own major physics goals. The first part of the LHCC statement certainly created motivation for keeping the costs as low as possible, and this was done in part by using existing magnets and/or magnet designs as much as possible, and using existing infrastructure. There was, however, obvious concern within FELIX that an initiative at I4 might be considered to be outside the LHCC guidelines, and so the collaboration addressed the LHCC in a memorandum (Bjorken, Eggert, Taylor; October 1996) outlining the detailed architecture of FELIX, along with the cost guidelines (25 MSF for the collisions; 50 MSF for the detector) which were assumed. No official reply was received, but there was tangible encouragement by CERN management and the LHCC chairman to proceed. It is here that a misunderstanding may have originated: CERN/LHCC seems to have interpreted the more than 150 people working on the LOI according to some kind of standard algorithm which converts the number of bodies appearing on proposals into the amount of money available. Regardless of the details of the algorithm, FELIX has always accepted the responsibility for identifying the sources of funding for the experiment, a point we have made repeatedly in meetings with members of the CERN management, as well as in the LOI.
This brings things back to the recent history. The LOI was submitted in August 1997, and in September the LHCC appointed the three referees, Altarelli, Ereditato, and Hartill. Considerable efforts to make contact with Hartill led to no success. Inquiries brought the information that the referees were asked to proceed slowly. Hence it was assumed that the collaboration should do likewise. The negative decision of the LHCC in November thus came as a complete shock. The rationales for this decision appear very unconvincing. The argument that the FELIX LOI violates LHCC guidelines is not consistent with the history we have recounted.
Might it be the physics which does not conform to the guidelines? The LHCC in its May 1995 guidelines only expressed an interest in diffraction, while the LOI contains much more. To the best of our knowledge, the committee discussed at most the diffraction physics. In any case, that is all that is mentioned in the LHCC report. Especially surprising to us is that the physics of high parton densities and very small x is not mentioned. While there are very few members of the LHCC who have dealt with this physics in any detail, we certainly expected that this would be more, not less, of a reason for asking the proponents, who are staking their careers on the physics, to make the case directly and in-person to the referees and to the committees.
The FELIX program has great potential in moving in creative directions unanticipated even by the collaboration, not to mention committees. The linear structure of the detector allows a staged approach. The physics menu, while possessing the very strong well-defined core outlined in the LOI, which we believe easily satisfies the criterion of cost-effectiveness, is still the least structured within the LHC program. Indeed Hartill's impression was that FELIX is a ``fishing expedition". While it is a stretch to characterize the validation of the Monte-Carlo codes in that way, there is a lot of truth in the characterization. The physics of extremely high parton densities already offers an opportunity for the occurrence of very novel phenomena. And it is nice to be put in the same category as other politically incorrect fishing expeditions like deep inelastic scattering, the SPEAR program, and the Brookhaven J experiment. The LOI itself discusses physics which is not yet in the literature, and it contains an invention by Sauli, the micro-TPC. FELIX would be the LHC detector which could most easily accommodate all those physicists with novel ideas.
But there still looms the problem of cost. The bottom-line issue is whether the 25 MSF investment in the creation of collisions is practical. The additional cost for the experiment is negotiable; there are a host of staging scenarios. Our discussions with the Director General and the comments of the chairman of the LHCC make it clear that the option of collisions at I4 has not yet been ruled out. In the words of the Director General, ``if a sufficiently good proposal came from a strong well supported group, [he] would be prepared to consider equipping I4, although it would have to be at the expense of some other activity in the already approved CERN programme." We welcome this position, and believe it important that the I4 option remain open, despite the obvious problems. We also believe it is important that it be reviewed again and formalized by the LHCC and the Research Board.
In summary, we believe the FELIX collaboration has already made significant potential contributions to the future LHC program. It has produced a compendium of novel physics topics outside the LHC mainstream. In addition, the collaboration has contributed the option of pA collisions, and the option of collisions at I4. Furthermore, a detailed lattice insertion has been produced which is transparent to the machine, which does not require a sixth IR for recrossing of the beams, and which serves as the architecture for a full-acceptance detector. This work was not at all straightforward, especially given the constraints of keeping the costs minimized.
We formally protest against the procedure by which the FELIX LoI has been considered by the LHCC and the conclusions of the LHCC. We insist that the FELIX LOI should be referred back to the LHCC, should be presented in an open meeting to the LHCC, and that the review process should include extensive opportunity for close dialogue with the proponents.
The LHCC and Research Board have, however, raised several critical points. We had originally expected to address such issues via direct interaction with the referees and the LHCC through the usual procedures. In the present situation, we believe that the best way of proceeding would be to present an addendum to the FELIX LoI to the LHCC which will contain a thorough discussion of the following points:
Further issues which should be addressed in this addendum may also be raised as the re-opened review process proceeds. In the meantime, FELIX welcomes all additional collaborators, and will continue to expand the collaboration, with particular emphasis on CERN member states. FELIX will also work to identify funding sources. Finally, the entire FELIX collaboration will continue to work on substantive issues as outlined above, and in the LOI.
We look forward to a positive response from the LHCC.
Sincerely yours,
The FELIX Collaboration