Present: J. Äystö, P. Butler (chair), E. Chiaveri, R. Garoby, B. Jonsson, O. Kester, J. Lettry, M. Lindroos, T. Nilsson, T. Otto, H. Ravn
1. REX ISOLDE integration
Mats Lindroos reported on REX-ISOLDE becoming a CERN facility and on the process of integrating REX into standard ISOLDE operation. The costs associated with this are staff costs for five additional staff members (4 in the AB division and 1 in the EP division) and an annual material budget of 170 kchf. It will for an interim period of maximum six years be covered by external grants. More than 75% of these grants have already been secured for the first three years. The research board will discuss this whole issue in its next meeting. In preparation for this discussion Mats and Peter has prepared an addendum to the ISOLDE MoU and sent a memo to the CERN DG to clarify the present status of the financing.
2. Hall extension
Peter Butler reported on the plans to extend the ISOLDE experimental hall (building 170). Plans and a cost estimate has been produced and the CERN site committee has approved the plans. The project will be financed from several sources including overheads on EU grants, the ISOLDE collaboration and the EP division. A request for a contribution from the DG has been done through the EP division. If the financing is resolved the hall could be ready in January 2005.
3. REX-ISOLDE upgrades
Oliver Kester reported on the planned upgrades of REX-ISOLDE. The new cavity for an upgrade to 3.1 MeV/u is now on the test bench in Munich and the amplifiers are under construction. The complete system should be installed this summer and be ready for physics in September 2003. Measures have been taken to assure that a possible delay with the amplifiers not should effect that date. The further up-grade to 4.2 MeV/u is not yet fully financed. Oliver has received a post from BMBF for the design of this system and the LMU group will apply for funds (800 kEuro) from DFG for the hardware. The aim is to have the system operational at REX-ISOLDE for the physics run in 2006. The preliminary design of this further upgrade shows that it is impossible to fit it and the necessary beam instrumentation in the present experimental hall.
Roland Garoby expressed some worry that the upgrades would increase the exploitation costs for the system. Oliver replied that this is not necessarily so as the new cavities will replace existing cavities and that the number of amplifier chains will stay the same as for the 3.1 MeV/u system.
Dieter Habs pointed out that the construction of MAFF is likely to start within the coming year and that due to his groups commitement to this project they will not be able to take main responsibility for any further upgrades beyond 4.2 MeV/u.
4. European Union funded research at ISOLDE
Peter Butler explained that ISOLDE is involved in 7 joint research activities within the EURONS (formerly I3NS) proposal to EU: SAFERIB, DILEP, IONTRAPS, INTAG, LASER, CHARGE BREEDING and EXOCHAP. ISOLDE has also asked for 1.7 MEuros from the access to European infra structure program.
5. Implications on ISOLDE ion sources and targets of a proton beam intensity upgrade
Jacques Lettry stressed that a possible future upgrade of the PS Booster and its injector to enable a primary proton beam current of 5-10 microAmps will require a R&D program on targets and ion sources, something which has to be included in the planning (five years) and budgeted for. Jacques gave a short summary of the foreseeable consequences that this rather moderate upgrade would have on ISOLDE target and ion source units:
The standard ISOLDE ion sources should in principle work with the possible exception of surface ion sources that could suffer from surface contamination caused by the higher flux of radioactive gasses. The ISOLDE ion source "work horse" of today, the Resonant Ionization Laser Ion Source (RILIS) should be straight forward to adapt for the new conditions. The target material will suffer from the higher proton beam flux and solid materials risks sintering. This can be compensated for by a combination of measures: an increase of the target radius and a defocusing and staggering of the proton beam. The effect of such modifications on e.g. the release times has to be studied in detail. The high voltage insulation at high primary and secondary particle fluxes (both the high voltage insulators on the front end themselves and the air between the target and beam-line/ faraday cage walls) could be a major point of concern. Already today we experience problems with the converter targets at 1.4 GeV. The new generation of ISOLDE front ends that now are being developed at should be more adaptable. The fact that they are physically split in two, an extraction part and and optics part, should permit adaptation of only the extraction part without the need to replace the entire unit. In particular, it should be investigated if all mechanical movement in the extraction system can be suppressed and replaced by deflectors and required optics elements.
6. Post accelerated radioactive beam development
Thomas Nilsoon summarized the results from the last off-line beam development period. Tests were done with He, Ar, Kr, Xe and a molecule, SeCo. The results were all positive but it is not possible to cool He (it can be captured and accumulated). Most of the SeCo came out as SeO2.
7. ECRIS developments
Prof. Micha Hass from the Wezimann institute has expressed interest together with the in-house technical and physics groups to investigate the technical feasibility and the physics interest for a low energy (approx. 60 keV to 1 MeV) facility at ISOLDE. It would use a highly charged beam from either an ECRIS source or the REX-EBIS source together with a high voltage platform. The ISOLDE upgrade group welcomes this initiative and encourages such a study.
8. Scientific case for an ISOLDE upgrade
Peter Butler has together with colleagues from the UK nuclear physics revised the physics case produced for the SIRIUS proposal for a possible document presenting a coherent physics case for a further upgrade of ISOLDE.
9. Future proton beam availability at CERN
Roland Garoby explained that he at present is chairing a study called HIP, which has got the mandate to study the present and future need of protons at CERN. The study should report to the AB division leader before the end of the year.
The present injectors can deliver protons as of today up until the start of LHC in 2007. The CNGS community will already from the start-up of CNGS need a higher intensity of protons than available today . A possible reduced cycle time of the PSB to 0.6 s would only increase the beam availability for ISOLDE but due to cooling limitations in the PSB ISOLDE would only benefit with a factor of 1.6. It is more optimum for both ISOLDE and CNGS to choose a cycle time of 0.9 seconds. The necessary investments for such an upgrade would be in the order of 2 FTE and 10-15 MCHF. An additional increase could come from a new booster injector, linac 4, which is under study. This new booster injector could increase the booster beam current by a factor of 2 but it evidently would require a major investment. An upgrade of the CERN injectors would not only benefit the fixed target physics at CERN but it would also reduce the LHC filling time.
10. Radiation safety consequences of an ISOLDE upgrade
Thomas Otto began by reminding the group that the induced activity in any irradiated element increases linearly with the integral of the beam intensity received which will mean that human interventions in the target area will be much more difficult than at the present facility. On average an intervention that today requires one week of radioactive cooling down time would in such a facility require one month of cooling down time. One safety system that definitely will need modification is the gas release system for e.g. the exhaust tanks at ISOLDE. This system is emptied after a long decay period but an upgrade would require that the release was more carefully monitored with a modernized measurement system. The same is true for gas release in connection with target changes, in particular UC and ThC targets.
Thomas stressed that it is very important that the safety issues are studied in parallel with the R&D for the upgrade and that they are properly budgeted for in the plans.
11. EURISOL
Helge Ravn explained that the EURISOL study is coming close to completing the final report. The choice is a 1 GeV proton driver with two ISOL target stations (100 microAmps maximum) and one target station capable of handling a MW converter type ISOL target. There will be a town meeting in ORSAY where the final report will be presented and the community will be given a last chance to give input to this report. A writing committee for a EU Design Study with the 6th FP on EURISOL has been formed. The members are Peter Butler, Fortuna and Dominique Gouette. The site issue will be handled by the design study.
12. AOB
Bjoern Jonson expressed a concern that there might be some overlap between the work performed by the ISOLDE upgrade group and the ISOLDE collaboration committee. Peter Butler replied that he will consider this when preparing the agenda for future meetings and that many upgrade issues anyway should be more openly discussed in e.g. the annual ISOLDE user meeting.
Mats Lindroos announced that there will be a workshop 18-21 March in Les Archs (Moriond meeting) on the beta-beam (a nouvelle concept for electron flavor neutrino beams). There are possible synergies between a betabeam facility and a next generation RNB facility.
Helge Ravn informed the group that there is interest from SNS to make target tests at ISOLDE for the study of cavitations in liquid targets. The tests would probably require an extended running period for which the potential user would have to pay.
12. Next meeting
The upgrade group will meet next time 23 September 2003.
Minutes by Mats Lindroos