Minutes of the thirteenth meeting on December 5, 1994


The ISC Chairman, Achim Richter, drew attention to the two main matters for discussion at the present meeting proposals for an accelerated radioactive beam and a programme of mass measurements of very short-lived nuclei) and also to the workshop on II-VI semiconductors that follows the present meeting.

H. Ravn, ISOLDE technical group leader, then noted in his report that great progress has been made in studies of shock wave phenomena in molten metal targets, tests of the laser ion source in which Nickel ions were produced for the first time at ISOLDE), and in the operation and development of the separator. The operation of the facility has been very stable, resulting in 430 physics shifts, of which 316 were online. He also mentioned that the installation of the high resolution separator would be terminated in 1995, and will increase the number of available targets to 30 and the number of online shifts to at least 300.

In the coordinator's report, O. Tengblad, presented a summary of the 1994 ISOLDE programme. The year 1994 has been a good year for ISOLDE; both equipment alignment and beam setup have been made easier, and while periods 1 and 2 suffered at times from low beam intensity and period 2 from lost proton pulses associated with lead ion beam development, period 3 saw a return to 1993 levels of performance.
O. Tengblad also noted that a real need for the high resolution separator is now being felt. The number of pending shifts has now been reduced to 250.

A presentation was then made of proposal ISC 94-25/P68 Radioactive beam experiment at ISOLDE: Coulomb excitation and neutron transfer reactions of exotic nuclei). This wide-ranging experiment involves the acceleration of ISOLDE beams up to 2 MeV/u and presents a novel method of doing so. The presentation was divided into two parts, the first involving the technical aspects and the second discussing a pilot experiment with the accelerated beam.

The open meeting continued with a progress report on experiment ISC 94-22/P28 Measurement of the lifetime of the O+2state in 76Kr) and a further presentation of Proposal ISC 94-26/P54 Mass measurement of very short half-lived nuclei). In the latter case, the spokesman had been requested after his original presentation at the 9th meeting to provide further information about the experiment's requirements. Finally, a status report and review of progress was given on the biomedical applications experiment carried out in conjunction with hospitals and medical centres in Basel, Geneva, and Pittsburgh; proposal
ISC 94-13/P48, ISC 94-13/P 48 Add.1 Use of radioactive ion beams for biomedical research).


Present: J.V. Allaby, B. Allardyce, J. Eades Secretary), D. Habs, L. Foà, D. Forkel-Wirth,
              H. Haseroth,  R. Helbig, A.Mueller, E. Moya de Guerra, H. Nifenecker, H. Ravn,
              A.Richter Chairman), K.Riisager, O.Tengblad, F.-K. Thielemann, P. Van Duppen.

After the Chairman had welcomed Prof. E. Moya de Guerra who was attending her first meeting as a committee member, and H. Haseroth who had agreed to evaluate the technical aspects of the proposal concerned with accelerated radioactive beams, the minutes of the last meeting were approved, and the committee proceeded to discuss matters arising from the Open meeting.

ISC 94-22/P28 Add. 1: Measurement of the lifetime of the O+2 state in 76Kr.

The committee was impressed by the results presented on electric monopole transitions in 78Kr and 80Kr, and agreed on the necessity of supplementing the beam time already used with the additional nine shifts requested in order to complete this small but interesting experiment by doing measurements of still unkown monopole transitions in 76Kr and 78Kr.

ISC 94-13/P42Add.1, P48Add.1: Use of radioactive ion beams for biomedical research.

The experiment had been approved by the Research Board on the ISC's recommendation with the proviso that the availability of the human and material resources necessary for its completion be clarified. It was agreed that this had been done and that the report showed impressive results which exceeded original expectations. There was no hesitation in granting the request for eight further shifts of beamtime.

ISC 94-25/P68: Radioactive beam experiment at ISOLDE: Coulomb excitation and neutron transfer reactions of exotic nuclei.

The committee was unanimously of the opinion that both the technical feasibility and the physics prospects of the proposal to conduct experiments with ISOLDE beams accelerated to 2 MeV/u had been convincingly demonstrated.

The proposed pilot experiment was seen as the forerunner of an ambitious programme of research covering several fields, and the committee felt that the possibility should be kept open to raise the energy of the accelerator somewhat from the 2.0 MeV/u proposed in order to guarantee the breadth of such a programme.

However the proposal comes at a time of great budgetary restrictions. These mean that the project would have to be seen as the main perspective of research with the PSB ISOLDE for some years to come, with concomitant side effects which reduce the prospects for other ISOLDE options. The committee decided therefore to recommend the project to the Research Board on the understanding that

a) it is regarded only as a modest extension of the present programme of investment in ISOLDE;

b) a detailed schedule of all costs be drawn up especially those concerning the extension to the experimental hall which would fall on CERN) in time for the next Research Board meeting in February 1995.

ISC 94-26/P54 Add. 2: Mass measurement of very short half-lived nuclei.

Decision on this proposal had been deferred from the 9th meeting to allow the spokesman to answer several questions concerning the characteristics required of the separator and the high voltage system. It was unanimously agreed that these have been adequately answered and that a sound physics and technological case has been established for carrying out the experiments as proposed, although the spokesman was further requested to investigate in detail the possibility of using a Penning Trap scheme as in proposal P68) as an injector for the RF spectrometer in a second stage of the experiment.

The Chairman will therefore recommend that the Research Board accept this proposal. A problem of accommodation of the rather voluminous apparatus over a period of some years nevertheless exists. Installation of P54 in the experimental hall extension required by the accelerated radioactive beam would evidently tie the timetable of P54 to that of P68, resulting in a further delay of approximately one year. For this reason, the possibility of finding space for P54 in the present hall should be carefully investigated in cooperation with the coordinator in time for the February Research Board meeting and a clear decision on both timetable and placement reached by then.

Other Business

The following Letters of Intent have been received:

ISC 94-21/I11: A radioactive-ion beam experiment for the study of the astrophysical RP-process
                              at CERN-Isolde.

ISC 94-24 /I12: Defect study in high energy ion implanted semiconductor.

ISC 94-27/I13: Energetic radioactive ion beam studies of hydrogen in semiconductors.

ISC 94-23 /I14: Gamov-Teller decay of N = Z even even nuclei above A = 60.

ISC 94-29/I15: Diffusion in highly immiscible systems.

It was noted that all these Letters of Intention except I14 require the accelerated radioactive beam.

The Chairman reminded members of the II-VI workshop to be held from 9.00 h. on the day after the present meeting, this having been originally requested by the ISC committee to coordinate the important part of the ISOLDE programme constituted by solid state physics.

The Chairman also thanked J.V. Allaby for his constant support of the ISOLDE programme during his 5-year period as PPE Division leader.

Dates of 1995 meetings:

                         13/14 February

                         15 May

                         28/29 August

                         27/28 November