CERN. Geneva. ISOLDE and Neutron Time-of-Flight Experiments Committee

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CERN/INTC 2001-016INTC 89 May, 2001ISOLDE AND NEUTRON TIME-OF-FLIGHTEXPERIMENTS COMMITTEE (INTC)Minutes of the eighth Meeting onMonday, 23 April 2001OPEN SESSIONThe Chairman opened the meeting by mentioning the changed deadline for proposal submissionwhich is now five weeks prior to the meeting instead of three, permitting a more thoroughrefereeing and the possibility to even out  the load on the Committee by deferring presentationsto later meetings. He continued by pointing out the recent decision by the Research Board thatthe lifetime of approved experiments at CERN should be two years after end of data-taking.Experiments wishing to be kept as active beyond this limit should appeal for this in writing tothe INTC. Furthermore, a rearrangement of the agenda was announced.The first presentation by P. Cennini concerned the second nTOF commissioning phaseperformed in early 2001. This started on April 2 and lasted for 12 days. The commissioningwas performed using 4 proton pulses/supercycle with 6 1012 protons/bunch. The target wasequipped with thermocouples inside and on the surface of the target which made it possible tostudy the thermal behaviour as function of the proton beam size, position and intensity. Insteady-state operation with nominal beam intensity, the maximum temperature reached was72°C and the thermal behaviour was in general according to simulations. Then he discussed theperformance of the facility measured by fission detectors at 182.5 m flight path, yielding anenergy resolution according to expectation.F. Käppeler then presented a status report on nTOF1/PS213 (Neutron TOF Facility, Technicaldesign Report) and the planned division of beam time by the collaboration for the rest of 2001and 2002. He described the installation of a permanent flux detector and a sample changer intothe neutron beam and various detector systems. So far, the Micromegas, the C6D6, BaF andBF3 –detector systems are installed and tested successfully. A plan for the forthcoming nTOFexperiments in 2001 was presented, starting with nTOF2 (Determination of the neutron fluence,the beam characteristics, and the backgrounds at the CERN-PS TOF Facility) which aims atbeam characterization, neutron fluence determination and tests of detector properties. Theintegrated number of protons needed to complete nTOF2 was given as 1.9 1018, in contrast tothe 7 1018 stated in the proposal. This was to be followed by nTOF3 (The importance of22Ne( a, n)25M g as s-process neutron source and the s-process thermometer 151Sm) and nTOF4(The Re / Os Clock Revisited). This program could be followed by a project aiming at studiesof the Th-cycle for ADS, the proposal for which is still in preparation. Six further proposals inpreparation were announced, regarding cross-section measurements for astrophysics, fissionand ADS to be done in 2002.The ISOLDE Technical coordinator, Mats Lindroos, gave an overview of the shutdown workachieved and the start-up of the ISOLDE facility. He described the background andconsiderations that had led to the exchange of the malfunctioning HRS front end for therenovated spare unit, installed during the shutdown. Within the ISOLDE consolidation project,the foundation for an entrance porch in front of the experimental hall had been cast and the hutfor the RILIS enlarged and modified to shield electromagnetic interference from the lasersbetter. He then described the accumulated technical problems that had occurred at the start-up,delaying it by one week. The most prominent of these problems was a vacuum leak at the GPSfront end which was provoked by an accidental air inlet, showing the fragility of this unit at theend of its nominal lifetime. The PS Management board had taken the decision not to attempt anycomplex repair of this front end, but to accelerate the construction of a spare unit.2This was followed by a report of the ISOLDE Physics coordinator, Thomas Nilsson, whopresented an updated ISOLDE physics schedule. As mentioned by the Technical coordinator,the start-up had led  to a delay which made it inevitable to cancel the first scheduled target. Thishad been put on the schedule at a later instance together with further adjustments triggered byupdated or changed time restrictions from the experiments. Due to the reallocations possible, theschedule still allows for delivering 380 shifts of radioactive ion beam to the experiments. Then abrief overview of the shift backlog was shown, followed by a status report on the REX-ISOLDE experiment. Here, the achieved results and remaining problems of the sub-systemswere shown, together with an updated time schedule for the completion and commissioning ofthe device.Following discussions with the CERN library, U. Köster presented future possibilities forelectronic submission of proposals by web. Apart from the large amount of paper copiescurrently needed, the proposals also have to be scanned by the CERN Document Server whichcauses excessive workload, decreased quality and a non-negligible fault rate.  He continued byshowing examples of other large-scale facilities where web-submission already had beensuccessfully implemented and accepted by the corresponding user community.The following proposals were then presented:P79 Add. 2 (INTC 2001-003): Magnetic Moment of  59Cu.P138 (INTC 2001-011): Investigation of astrophysically relevant neutron-rich argon nuclei.P140 (INTC 2001-014): Doping Properties of Ferromagnetic Semiconductors investigated bythe Hyperfine Interaction of Implanted Radioisotopes.CLOSED    SESSIONPresent  : J. Äystö, C. Détraz, J. Eades (Secretary), H. Flocard (Chairman), M. Hauschild,H.-J. Kluge, K.-H. Langanke, K.-P. Lieb, M. Lindroos, E. Migneco, T. Nilsson(Acting Secretary), H. Ravn, J.-P. Riunaud, C. Rossi-Alvarez, B. Rubio,J. Suhonen, R. Voss, D. Warner.Apologies   : W. Scobel, J.-P. DuraudThe Chairman first welcomed M. Hauschild, the SPS/PS coordinator who, following thedecision in the preceding INTC meeting, henceforth joins the Committee as an additional ex-officio member. He then pointed out that the current meeting was the last where John Eadesheld the function of Scientific Secretary, and thanked him for his excellent work and theenjoyable collaboration. Thomas Nilsson will take over  this duty hereafter.Apart from  typographical errors, the minutes of the seventh meeting were approved with thefollowing change; p. 4, section 8: “the six requested shifts” should be “six shifts for that part ofthe proposal out of the total of eighteen requested”The Chairman then reported the successful completion of the tests on electron beam-inducedphotofission for production of radioactive nuclei, using the LPI shortly before shutdown (I38).The support given by the PS division in these measurements was acknowledged.This was followed by a discussion on the delivered scientific and technical reports as follows:1.   ISOLDE    Technical   report  The Committee took note of the shut-down work and start-up problems encountered asdescribed by M. Lindroos. The Committee expressed its support for the plans to accelerate theproduction of a spare front end, and C. Détraz pointed out that the Research Board in its lastmeeting expressed a similar support.32.   ISOLDE    Scientific   report  The Committee took note of the updated schedule shown by T. Nilsson. Then a discussion onREX-ISOLDE followed, focussed on a possible future transition from an experiment to ageneral facility, attracting a user community beyond the current collaboration. It was pointed outthat this matter is addressed in the recently revised MoU between CERN and the ISOLDECollaboration and that any such transition would evidently involve the PS division. The furtherdiscussion will take place when REX-ISOLDE has become operational.3.    nTOF    commissioningThe Committee took note of the tests made with sensors attached to the target and the firstresults on the performance of the facility, and looks forward to receive the updated TDRincluding these results.4.    nTOF    Experimental    programmeAfter some discussion on the consequences of the reduced number of protons now needed toperform the experiments, the Committee took note of the successful completion of thecommissioning and the progress of nTOF2. Regarding nTOF3 and nTOF4, the request for anominated Spokesperson expressed in the last Research Board meeting was reiterated.5.      Web-submission    of    proposalsThe Committee expressed its willingness to participate in such a change of submissionprocedures, but left the decision on details and implementation to CERN. However, theCommittee opted for a transition period in which both traditional submission of paper copiesand electronic submission would be possible to exclude any disruption. R. Voss stated that ifthe procedure is successful it may be followed by all experimental review Committees atCERN.The presentations made during the open meeting of the new proposals and addenda were thendiscussed.6. P79 Add. 2 (INTC 2001-003): Magnetic Moment of  59Cu.The proposed measurement of the magnetic moment of 59Cu was considered as importantinformation in its own right, and interesting for large-scale shell model calculations.Furthermore, the input is valuable for the already approved experiment IS381. Thus, therequested 6 shifts will be recommended to the Research Board.7. P140 (INTC 2001-014): Doping Properties of Ferromagnetic Semiconductors investigated bythe Hyperfine Interaction of Implanted Radioisotopes.The Committee found the proposal interesting and fitting to the ISOLDE programme, using abroad range of isotopes not available elsewhere. Thus, it will be supported for the requested14 shifts at the Research Board. The collaboration is expected to return with a progress reportbefore the end of 2002.8. P138 (INTC 2001-011): Investigation of astrophysically relevant neutron-rich argon nuclei.The proposed measurements were considered as interesting, both as input to astrophysicalnetwork calculations and from the viewpoint of nuclear structure. However, the experimentalsituation was considered as somewhat unclear since the experiment relies on reaching animproved background suppression, while clear numbers for the expected improvements are notstated in the proposal. Thus, pending a letter of clarification of the experimental situation andthe technical aspects of suppression of contaminants, the final shift recommendation wasdeferred.49.   ISOLDE    shift    backlogFollowing the procedure adopted in the previous assessment of the ISOLDE shift backlog, theexperiments in question had been subdivided into three classes. The first class contained thethree pending REX-ISOLDE experiments approved before 1999, IS347, IS367 and IS371.Here, T. Nilsson gave a short report on the status and highlighted that the limiting factor wasthe completion of the post-accelerator itself. The Committee decided to maintain theseexperiments until REX-ISOLDE is operational. Furthermore, it expressed its wish that REX-ISOLDE start as early as possible, permitting these experiments to reach completion in 2002.The second class contained experiments recommended before 1999 with more than 20% of theshifts outstanding, IS303, IS357 and IS370. Here, all experiments have requested theremaining beam time within the running period of 2001 and stand a good chance of completingtheir projects. Thus, it was decided to leave unchanged the shift allocation. On the other hand,any remaining allocation after the end of operation in 2001 will be withdrawn. The third classconcerned experiments recommended before 1997, IS338, IS356 and three test experiments, allhaving not requested beam in 2001. Here, the spokespersons had been contacted prior to themeeting by the Chairman and all agreed to the cancellation of their shift allocation. Thus, theallocation for these experiments was withdrawn. However, IS338 and IS356 requested to bekept on the list of active experiment since submission of addenda was planned by both groups.10.    Letter    concerning    P135   : Beta-Decay study of very neutron-rich Cd isotopes with a chemicallyselective laser ion source (L.o.I. I22, 16.4.97).The spokesperson of P135 had sent a letter to the Committee with answers to the questionsraised in the seventh meeting. The Committee found that herewith satisfactory answers weregiven regarding the questions expressed in the previous meeting and the 12 additional shifts willbe recommended to the Research Board.OTHER BUSINESST. Nilsson reported that very promising machine development work was in progress at the PS-division. The first investigations of a more rapid cycling of the PS Booster, with a base periodof 0.6 s instead of 1.2 s, had encountered no major technical obstacles so far although majorwork remained to be done. The prospect of ultimately having twice the number of proton pulsesavailable from the PSB would mean that the agreed proton beam intensity for ISOLDEaccording to the Memorandum of Understanding could be delivered and exceeded withoutcausing implication for other proton beam users at CERN. Furthermore, increased target life-time could be expected through a more regular pulse structure. The positive perspectives of thisprospect were confirmed by the PS representatives and the SPS/PS coordinator who pointedout that nTOF could also benefit from such a change. In view of the established interest inphysics with radioactive ion beams, the Committee expressed its support for any technicaldevelopment that could aid in assuring the required proton beam intensity for ISOLDE andnTOF and recommended that CERN pursue the above developments described with as highpriority as possible.The next meeting is on Monday, September 24 , and the deadline for submission ofproposals is Friday, August 17, 2001.The date of the remaining INTC meeting for 2001 is:November, 26-27.Thomas NilssonTel. 73809 - 75828 (Mobile: 160985)Thomas.Nilsson@cern.chINTC Secretariat  : Monique Budel (Bldg.14/4-022); Tel. 76 74270Monique.Budel@cern.ch

Minutes of the eighth meeting on Monday 23rd April 2001

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