ISOLDE EXPERIMENTS COMMITTEE
Minutes of the nineteenth meeting on
2 December, 1996
 

OPEN SESSION:

The Chairman welcomed W. Gelletly of the University of Surrey, Guildford to his first meeting as a member of the ISOLDE committee, and also H. Wenninger who was replacing L. Foà at the meeting.

H. Ravn, ISOLDE Technical Group Leader then presented his report, summarising the main jobs done in 1996, with particular reference to the online use of molten metal targets, which are also of interest to the Energy Amplifier project, the European Spallation Source project, and the Muon-Muon collider project. He further discussed developments concerning lanthanum carbide targets and the peformance of the High Resolution Separator. Referring to the now well-known problems with the radioactive target handling robots, he described the solution negotiated between CERN and the robot contractor. This involves an upgrade to be carried out by the contractor that it is now expected to be finished by mid-January. H. Wenninger assured the open meeting that the CERN management was ready to support the ISOLDE community with all necessary help in this crucial matter, and H. Ravn agreed to keep the ISOLDE community informed about the progress of the upgrade.

In a contribution to the open meeting outside the published agenda , G. Bollen described progress on the REX ISOLDE project, in which the 60 keV beam will be post-accelerated after transfer to a Penning trap. The progress here is very encouraging, with the project on a sound basis and the collaboration functioning well and efficiently. The project has been financed adequately from a variety of of sources inside and outside CERN, and is expected to be operational two years from now. The time is evidently ripe for the preparation of proposals.

The ISOLDE coordinator then presented her report for 1996 and a draft schedule for 1997, and described the modifications recently undertaken to extend the ISOLDE experimental hall. Clearly the ISOLDE performance in 1996 has suffered from the robot problems, these having affected 40% of the experiments and resulted in a loss of 70 shifts, but many excellent physics results have nevertheless been obtained. The 1997 programme will inevitably be affected also, although it will not be possible to gauge accurately the extent of this until the robot problems have been solved. She reminded users that in common with all CERN machines, ISOLDE will begin its winter shutdown on December 1, this being one of CERN's general economy measures. The draft schedule takes account of two other constraints, the absence of a high intensity proton beam from Oct ober 1 until November 23, and the imposition of new radiation safety requirements by TIS.

Presentations were then made of the following new proposals and progress reports:

1. Proposal: Magnetic Moment of 67Ni Oxford - Maryland - Michigan State University);
    CERN/ISC 96-28/P79; J. Rikovska.

2. Proposal: Measurement of the Magnetic Moment of T = 3/2 Nuclei in the S-D Shell using
    the tilted Foil Polarization Technique; Manchester - Weizmann Institute, Rehovot - Hahn-Meitner
    Institute, Berlin - Legnaro Laboratory, Padova); CERN/ISC 96-31/P87; M. Hass.

3. Proposal: Electron Paramagnetic Resonance Investigations of Isolated Impurities and Impurity
     Pairs in Silicon CERN - TU Berlin); CERN/ISC 96-23/P83; A. Näser.

4. Addendum to proposal P81 IS357): Gold and Platinium in Silicon-Isolated Impurities and
     Impurity Complexes Aarhus - Amsterdam - Dublin - Konstanz - Lisboa CERN Collaboration);
     CERN/ISC 96-26/P81 Add.1; C.A.J. Ammerlaan.

5. Proposal: Surface Studies by Nuclear Stimulated Desorption Berlin - CERN - Rutgers -
    Tel Aviv Collaboration); CERN/ISC 96-25/P84; I. Kelson.

6. Proposal: Investigations of Deep-Level Fe-centers in Si by Moessbauer Spectroscopy; Aarhus -
     Berlin - Göttingen - Konstanz - Troitzk - CERN Collaboration); CERN/ISC 96-29/P85; G. Weyer.

7. Proposal: Studies of High-Tc Superconductors Doped with Radioactive Isotopes;
    Aveiro - Göteborg - Grenoble - Leipzig - Leuven - Lisboa - Porto - Sacavém - Stockholm -
    Warsaw - CERN Collaboration); CERN/ISC 96-30/P86; J.G. Correia.

CLOSED SESSION:

Present: B. Allardyce*, R. Ammerlaan, G. Bollen, J. Eades Secretary), D. Fick, D. Forkel-Wirth,
             W. Gelletly, D. Habs, E. Moya de Guerra, H. Nifenecker, K. Peach replacing G. Goggi),
              H. Ravn, A. Richter Chairman), H. Wenninger replacing L. Foà)

* part time

Apologies: F-K. Thielemann, L. Foà, G. Goggi

The Chairman welcomed W. Gelletly, H. Wenninger and K. Peach to the closed session, and the minutes of the eighteenth meeting were approved after minor typographical errors had been recognised.

In discussion of the technical group leader's report, the committee expressed its appreciation of the impressive work done by H. Ravn and his colleagues under the extremely difficult conditions imposed by events over which they had no control. H. Ravn was able to announce that the robot contractor company had today agreed to send its personnel to CERN on December 5, and that the upgrading work was therefore expected to go ahead on schedule. H. Wenninger reiterated that CERN recognised fully the crucial importance to the ISOLDE programme of a speedy solution to this problem, and will guarantee all the technical and other help necessary to bring the work to a successful conclusion, thereby permitting heavy target work to proceed. In the case that no remedy is found during the winter shutdown, a fallback solution will be made available that satisfies the requirements of the Technical Inspection and Safety Group.

The committee noted with great pleasure the progress made on the REX ISOLDE project and expressed its satisfaction that the project's funding is secure and that responsibilities within the collaboration appear to be well defined; it therefore encourages the ISOLDE community to go ahead with the preparation of proposals for experiments. It was also noted that the REX ISOLDE mini-ball might attract other users, since it is likely to be useful in other nuclear physics programmes.

In a short discussion of the Coordinator's report, the committee was happy to note the high quality of the work reported at ISOLDE during the course of the year in spite of the many lost shifts.

The meeting continued by a discussion of the proposals and progress reports presented in the open session, as follows:

P79: Magnetic Moment of  67Ni

The proposal received general assent as being sound in conception, well argued and well documented. It is expected that the theoretical support necessary for interpretation of the results will be found. The experiment will therefore be recommended to the Research Board for the 16 shifts requested.

P87: Measurement of the Magnetic Moment of T = 3/2 Nuclei in the S-D Shell using the TiltedFoil
         Polarization Technique

Generally the programme of work for measuring the magnetic moments of T=3/2 nuclei with the tilted foil technique was considered to be worth while, although it was agreed that it should be better focussed on specific nuclei, instead of attempting to cover a large field of data, much of which might be less interesting and useful. In particular, doubt was expressed about the achieveable precision of the proposed Mg33 quadrupole moment measurement. The committee therefore agreed to allocate 12 shifts to the experiment. The proposal being of the nature of an addendum to an earlier proposal, it was felt unnecessary to seek further approval from the Research Board.

P83: Electron Paramagnetic Resonance Investigations of Isolated Impurities and Impurity Pairs in
        Silicon, and
P81 Add.1: Gold and Platinium in Silicon-Isolated Impurities and Impurity Complexes

These two proposals, being very similar in aims were discussed together. The committee remained unconvinced that P83 would achieve the sensitivity necessary to reach the desired goal, in contrast to P81 for which the case was considered to be well-proven. Only P81 was therefore accepted by the ISC, for which eight shifts will be allocated. As this is an addendum to an earlier proposal, no Research Board approval will be necessary.

P84: Surface Studies by Nuclear Stimulated Desorption

It was thought that results to be expected from Nuclear Stimulated Desorption of deposited 107Cd would be very difficult to interpret. This technique was not therefore considered to be the right one for the anticipated surface studies, the general opinion being that the STM method would have been a much more suitable choice. The committee decided therefore not to recommend scheduling of this experiment.

P85: Investigations of Deep-Level Fe-centers in Si by Moessbauer Spectroscopy

The two main expectations from this experiment were the determination of the dependence of Fe diffusivity on the charge state, and the study of Fe substitutional sites. These were thought to be promising lines of research, and the necessary expertise was considered to be present in the collaboration. The ISC therefore will recommend to the Research Board that 12 shifts be allotted to these measurements.

P86: Studies of High-Tc Superconductors Doped with Radioactive Isotopes

The proposal was generally thought to be well organised and presented, and to represent a worthwhile research programme in the fundamental and fascinating field of high-temperature superconductivity. The proposal will therefore be recommended to the Research Board for 18 shifts, after which a progress report should be presented.

Other Business

An outstanding request for a further 10 shifts was approved for experiment IS338, the first measurements having been done well and a convincing argument having been made for supplementing them.

Dates of meetings in 1997:

        10-11 February

        12-13 May
 
        29-30 September

        8-9 December.

                                                                                                                                                    John Eades