ISOLDE EXPERIMENTS COMMITTEE
Minutes for the eighteenth meeting on
13 May, 1996
 

OPEN SESSION:

The Chairman first welcomed to the ISC committee Prof. C.A.J. Ammerlaan of the Van der Waals Laboratorium, Amsterdam, whose expertise will be invaluable in evaluating solid state physics proposals. He also announced the presence of Dr. S. Harissopoulos, General Secretary of the Hellenic Nuclear Physics Society, who has expressed interest in joining the ISOLDE community and is presently investigating the possibilities of doing nuclear physics experiments at ISOLDE.

After brief reports by the ISOLDE Technical Group Leader and the ISOLDE Co-ordinator, presentations were then made of the following new proposals and progress reports:

1. Proposal: gI-factor measurements on unstable Eu+ isotopes in an ion trap Mainz, CERN,
     GSI-Darmstadt Collaboration); CERN/ISC 96-9/P78; G. Werth.

2. Proposal: Search for physics beyond the Standard Model via positron polarization measurements with
    polarized 17F Leuven, Louvain-La-Neuve, Bonn, Madison, Zürich, NICOLE &ISOLDE
    Collaboration); ISC 96-11/P80; N. Severijns.

3. Proposal: Study of the eu correlation in Fermi beta decay: a probe for scalar weak interactions
    Notre Dame, Seattle, Madrid, CERN Collaboration); CERN/ISC 96-17/P82; A. Garcia.

4. Addendum to proposal P60 IS344)): Laser spectroscopy of neutron rich Bismuth isotopes CERN,
    Mainz, Manchester, Stony Brook Collaboration); CERN/ISC 96-12/P60 Add.1; J. Billowes.

5. Proposal: Gold and platinum in silicon-isolated impurities and impurity complexes; Aarhus, Dublin,
     Konstanz, Lisboa, CERN Collaboration); CERN/ISC 96-15/P81; M. Henry.

6. Addendum to proposal P40 IS328): Electrical activation of Dopant atoms in the II-VI materials M-X
    M = Zn, Cd and X = S,Se,Te) Saarbrücken, Konstanz, Berlin, CERN Collaboration);
    CERN/ISC 96-14/P40 Add. 2; Th. Wichert.

7. Addendum to proposal P35 IS325): Combined electrical, optical, and structural investigations of
     impurities and defects in wide-gap II-VI semiconductors CERN, Berlin Humboldt-Universität,
     Berlin Technische Universität, Jena Collaboration); CERN/ISC 96-16/P35 Add.1; M. Wienecke.

8. Addendum to proposal P62 IS342): Emission channeling studies on the lattice location of lithium,
    sodium and rare earth isotopes in semiconductors Konstanz, Leuven, CERN, Durban-Westville
    Collaboration); CERN/ISC 96-13/P62 Add.1; U. Wahl.

9. Addendum to proposal P64 IS343): Test of a high power target design; CERN/ISC 96-18/P 64 Add. 2
    CLRC, CERN, Brighton, Liverpool, Manchester, Surrey Collaboration); R. Bennett.
 

CLOSED SESSION

Present: C.A.J. Ammerlaan, B. Allardyce, G. Bollen, J. Eades Secretary), D. Fick, G. Goggi,
              D. Habs, L. Foà, D.Forkel-Wirth, A.Mueller, E. Moya de Guerra, H. Ravn,
              A. Richter Chairman), K.Riisager, F-K. Thielemann.

Apologies: H. Nifenecker.

After welcoming Prof. C.A.J. Ammerlaan to the closed meeting, the Chairman announced that
Prof. F.K. Thielemann had agreed to continue as a committee member for a further two years.
The minutes of the seventeenth meeting were then approved without change.

Proposal P79 Odd-A Gadolinium Sources for Laser Spectroscopy, ISC 96-10/P79) was then briefly discussed; it was agreed that as the proposal requested only one shift, this could be arranged within the discretionary powers of the Co-ordinator, and that it should be reclassified as a Letter of Intent
ISC 96-10/I19). The Chairman also announced that he had received a Memorandum
CERN/ISC 96-20,ISC/M7) showing that the noise problems resulting from the operation of gas-discharge lasers in experiment IS333 had been solved. The conditions for the continuation of IS333 Request for beam-time, ISC 96-20/M7) mentioned in the minutes of the seventeenth meeting
CERN/ISC 96-8, ISC 17) were thus considered to have been largely fulfilled, and the experiment can now be scheduled for the less critical ten shifts of 128Ag measurements. Further allocation will be made for the astrophysically interesting 129Ag experiment when experience has been gained in this way. The committee then proceeded to discuss the proposals and progress reports presented in the Open meeting.

P78: Proposal: gI-factor measurements on unstable Eu+ isotopes in an ion trap

The committee agreed that the approach outlined for mesuring gI-factors on unstable Eu+ isotopes in an ion trap was technically feasible and appropriate, but that the physics value of the proposed measurements would have to be established by a firm theoretical treatment before the proposal can be recommended to the Research Board.

P80: Search for physics beyond the Standard Model via positron polarization measurements with
         polarized 17F

The committee felt that this Particle Physics/ Nuclear Physics borderline experiment would be a valuable complement to high energy experiments placing bounds on the WR-boson mass. The experiment will therefore be recommended to the Research Board. However, owing to the large number of shifts involved 46), an interim report will be required after the initial data-taking runs.

P82: Proposal: Study of the eu correlation in Fermi beta decay: a probe for scalar weak interactions

In the opinion of the committee, the proposal makes a strong case that better rejection of positron background would result in a statistically more significant result than the previous version of the experiment IS334). It was therefore agreed that the proposal should be considered as an extension of that experiment and considered as an Addendum to the original proposal P50). The 20 shifts requested will therefore be allocated without further recourse to Research Board approval.

P60 Add.1: Laser spectroscopy of neutron rich Bismuth isotopes

The additional measurements on 214,215)Bi proposed in P60 Add. 1 were considered to be necessary to complete the sequence of bismuth measurements and to follow up interesting discrepancies with the theoretical calculations, as well as to complement other experimental studies in the mass region around 208Pb. The 15 shift extension will therefore be allocated as requested.
 

P81: Gold and platinum in silicon-isolated impurities and impurity complexes

It was agreed that the proposed study of gold and platinum impurities in silicon can make an essential contribution to a deeper understanding of a field in which current knowledge is currently empirical only. The 12 shift request will therefore be supported by the Chairman at the Research Board.

P40 Add.2: Electrical activation of Dopant atoms in the II-VI materials M-X
         M = Zn, Cd and X = S,Se,Te)

The committee noted that systematic progress had been made during the last two years in undestranding the doping of II-VI compounds, and that important industrial applications could follow the discovery of suitable dopant. A further 25 shifts will therefore be added over a period of two years to the six outstanding ones already allocated. Nevertheless, the beam time should be shared with another ISOLDE user if one such can be found.

P35 Add.1: Combined electrical, optical, and structural investigations of impurities and defects in
      wide-gap II-VI semiconductors

It was not easy to assess progress on all the techniques used on the basis of the presentation, although it was understood that some of the topics not dealt with were covered by in-press publications. It was therefore decided to allocate nine additional shifts in addition to the four remaining from the original request, with the proviso that the required beam intensity conditions be realised in close collaboration with the ISOLDE technical group leader and the . The collaboration was also asked to present a fuller account of its results to the ISC in about one year.

P62 Add. 1: Emission channeling studies on the lattice location of lithium, sodium and rare earth
      isotopes in semiconductors

The addendum addresses three widely differing physics topics with a common technique, and requires a substantial number of shifts. The committee noted the progress already made and approved the scheduling of ten shifts to finish the 8Li measurements. The fifteen shifts for Na experiments will also be approved but only when it has been established that the intensity required can be achieved. The five shifts for rare earth measurements will be approved at an appropriate time in the future when the target can also be used for other purposes. This should be done in close collaboration with the ISOLDE technical group.

P64 Add. 2: Test of a high power target design

The continued help of ISOLDE is clearly an essential element to the success of the RIST project at ISIS. It therefore was agreed to allocate the three necessary shifts to complete the high power target studies already begun.

Other Business

The CERN Research Director, Lorenzo Foà informed the ISC that the funds needed for increasing the Booster energy to 1.4 GeV and staggering the proton pulses extraction can be found provided that they can be offset against economies in power consumption made by not running ISOLDE in December from 1997 onwards. A possible problem here is that the IS304 requirement of six equidistant shots can only be accommodated in the month of December. D. Forkel will investigate possible solutions for this problem.

Finally the Chairman took note of the fact that the term of office of A. Mueller and K. Riisager ends with the current meeting, and thanked them both for their invaluable contributions to the committee's work.

Dates of next meetings: