CERN/INTC 2005-006                                                 
INTC-022                                                                
01.03.2005


ISOLDE AND NEUTRON TIME OF FLIGHT
EXPERIMENTS COMMITTEE

Minutes of the Twenty Second Meeting of the INTC
Held on Monday 21 and Tuesday 22 February 2005

  

OPEN SESSION

 

Monday 21 February 2005 at 13:30 h, Council Chamber

 

 

The Chairman of the INTC, Juha Äystö, opened the meeting by stressing the importance of the year 2005 for ISOLDE,
in view of the unique opportunity afforded by the fact that ISOLDE will be the only user of the PS Booster PSB),
and its impact for the ISOLDE community and its scientific production.

 

 

The ISOLDE Technical Coordinator, Mats Lindroos, reported on the technical activities at ISOLDE.
He first reviewed the status of the REX-ISOLDE facility. The integration in the AB department is underway, the main
shortcomings being the lack of technical support for the REX-ISOLDE low-energy stage and the additional workload
for a small section of the AT/VAC group. The first stage of migration of the power supplies and control system to
AB standards will be carried out in 2005, involving the AB/PO and AB/CO groups. The AB/BDI group has already
been contacted to discuss the support for beam instrumentation. In 2005 the PC-based control system will be maintained
by the AB/CO group via an industrial support contract. A project associate will join in spring 2005 to work on
REX-ISOLDE instrumentation. The REX-ISOLDE operation and maintenance was then discussed. The operation of the
REX-LINAC is expected to become much more stable after a foreseen modification of the 200 MHz RF cavity.
Furthermore, it will be possible to operate the REX-LINAC with a repetition rate of 100 Hz from July/August 2005,
which can positively impact experiments with short-lived species. The major problem of peak staff needs during
the setting-up and running of REX-ISOLDE remains for 2005. It is proposed to form a minimal supervisor team
for 2005 and study a long term solution involving AB/OP group. Machine development time will be allocated in the
schedule to allow for setting-up and for development of new beams.

He then reported on the progress of the ongoing shutdown activities at ISOLDE. The maintenance of the ventilation
and cooling water system has been completed and work has been carried out in the optics of the ISOLDE
beamlines. The latter includes the reconfiguration of the MISTRAL beam line and improvements of the HRS
transmission by adding a new quadrupole. The radioactive class A
laboratory for target manipulation will be completed
in time for the 2005 run. Test of the new front end #6 have been started, it will be ready as a spare for the 2005 campaign.
A grant has been received in the UK to fund the RFQ cooler project; the assembly and offline tests will be
completed in 2005. The installation is foreseen for the 2005–2006 shutdown, provided the off-line tests are satisfactory.
In addition, there is an application in preparation in Sweden for funds to replace the copper vapour lasers of the RILIS
by new pump lasers. The operation of the facility in 2005 was then examined. An engineer in charge EIC) will be on
duty in the ISOLDE control room from 9:30 to 11:30 for all runs during the 2005 campaign and a new visible indication
of the EIC on duty will be implemented. A work-package for support of the ISOLDE experimental area including
REX-ISOLDE has been devised to account for the lack of support dating back to the fusion of the SL and PS divisions
in January 2003.

 

The ISOLDE Scientific Coordinator, Luis M. Fraile, reported on the conditions for the 2005 schedule, with ISOLDE
being the single user of the protons from the PSB. The approved accelerator schedule includes a 27 week period for
physics at ISOLDE, from 25 April to 31 October. Twelve 4-hour time slots for access to the PS and six 8-hour periods
for machine development at the PSB will be granted during the year. Furthermore, 2 out of 12 proton cycles will be
used for parasitic machine development for the PSB once a week.

The reduction of the basic cycling period of the CERN accelerators and its impact on ISOLDE was then addressed.

This has been presented  by the High Intensity Proton beams working group at AB as a possible solution of the
deficit of SPS cycles for fixed target physics and of the decreased performance of ISOLDE once CNGS starts operation.
A new cycle of 900 ms has been devised as a short-term upgrade compatible with the current cycle structure and
with the existing hardware and control system. This will immediately result in a 33% increase on the number of proton
pulses for ISOLDE, but the equipment lifetime and radiation aspects should be monitored. The larger number of
available cycles for ISOLDE will allow reducing the peak intensity and extend the target units lifetime.

The implementation of the 900 ms cycle was approved by the Management Board of the AB department on 06/12/04.
The proposed approach consists of a test for the LINAC2 and PSB in 2005. The plan is to start at the standard 1200 ms
cycling and prepare the 900 ms scheme in parallel. The switchover to 900 ms will be then carried out in one week of tests
without any beam. In the following two weeks the proton beam would be delivered to ISOLDE with the new 900 ms
cycle, and thus with higher intensity, but with risks of interruptions. An additional week without beam would be used to
change over to 1200 ms again. A similar test scheme will be used in 2006 for the PS and SPS machines. The dates for the
tests and implementation in 2005 are still to be defined by the PSB machine supervisor, and should avoid the LEIR
commissioning starting 1 August and the summer period. The most likely period are weeks 21 to 24. The immediate
impact for ISOLDE on the present campaign will be a reduced operation time to 25 weeks, with 2 more weeks with risk
of interruptions. Under these conditions a maximum of 300 radioactive beam shifts can be scheduled. There are 579 outstanding
shifts from previous approvals, out of which 212 are for REX-ISOLDE physics.

Other boundary conditions were then pointed out, and in particular the increased demand on the RILIS at ISOLDE, which
exceeds the restriction of 150 physics shifts per year. This renders the RILIS equipment and manpower situation extremely
critical for the success of the facility; the experimental groups were asked to contribute to the RILIS operation in any
possible way. Other limitations include the number of uranium carbide targets that can be produced by the AB/ATB/IF group,
and the REX-ISOLDE operation and the scheduled migration of REX-ISOLDE power supply controls 2 weeks).
One further constraint has been released, namely the presence of the Miniball detector at ISOLDE. According to
the schedule of transfer of MINIBALL from GSI to CERN decided by the Miniball steering Committee on 11 February 2005,
the move will start on 20 April and Miniball will be ready for experiments at ISOLDE on 20 May 2005. The schedule will
be fixed as soon as all requests are received and the plan for the implementation of the 900 ms scheme is decided.

Finally some practical issues were discussed, including the ISOLDE shutdown courses for users that were held at
end of 2004, and were overbooked, and the works on the extension of the ISOLDE hall, which are on schedule.
The dust barrier protecting the experimental hall will be kept until mid April to allow for electrical installations and
painting on the new extension.

 

 

The following proposals and status reports were then presented:

 

1.     Search for new physics in beta-neutrino correlations using trapped ions and a retardation spectrometer
CERN-INTC-2005-014/P111 Add. 1), N. Severijns.

 

2.     Studies of colossal magnetoresistive oxides with radioactive isotopes CERN-INTC-2005-016/P132 Add.1),
V. Amaral.

 

3.    Measurement of gas and volatile elements production cross section in a molten lead-bismuth target
CERN-INTC-2005-017/P171 Add.1), L. Zanini.

 

4.     Elastic scattering and fusion studies in the reactions 10,11Be+64Zn CERN-INTC-2005-003/P192), A. Di Pietro.

 

5.     Coulomb excitation of odd-mass and odd-odd Cu isotopes using REX-ISOLDE and Miniball
CERN-INTC-2005-004/P193), G. Georgiev.

 

6.     A study of the r-process path nuclides, 137Sb, 138Sb, 139Sb using the enhanced selectivity
of resonance ionization laser ionization CERN-INTC-2005-001/P191), W. Walters.

 

7.     High accuracy mass measurement of the halo nuclides 12,14Be CERN-INTC-2005-009/P195),
M. Sewtz.

 

8.     Precision measurement of the half-life and the b-decay Q value of the super-allowed 0+ -> 0+ b-decay of 38Ca
CERN-INTC-2005-013/P196), D. Lunney.


CLOSED SESSION

 

Monday 21 and Tuesday 22 February 2004

 

Present: S. Åberg J. Äystö Chairman), P. Butler, T. Butz, J. Engelen, L.M. Fraile Secretary), M. Hauschild,
D. Hilscher, M. Lewitowicz, M. Lindroos, G. Neyens, F. Priolo, D. Schinzel replacing E. Radermacher), P. Woods.

 

Apologies: H. Doubre, M. Huyse, R. Kruecken.

 

1.     INTRODUCTORY REMARKS BY THE Chairman

The Chairman of the INTC, Juha Äystö, opened the session and welcomed the new members of the Committee.
He reminded the Committee of the procedure for evaluation of the experiments proposals, which should include the
judgement of the scientific merits, the viability, and the suitability of the requested number of shifts. The INTC is advisory
to the Research Board RB), thus it only makes recommendations to the RB for a final decision on the approval of
the experiments.

 

2.     MINUTES OF THE LAST MEETING

 

The minutes of the eighteenth INTC meeting from 15 and 16 November 2004 were approved without amendments.

 

3.     STATUS OF ISOLDE

The Chairman of the Committee stressed the importance of this year for ISOLDE, with basically all the protons from the PSB
delivered to the facility. He then remarked that the number of outstanding shifts from previous Committees at ISOLDE is
approaching 600. Next he stated that the CERN management has requested that ISOLDE and nTOF organize a special
scientific workshop to discuss present status and perspectives of the physics covered by the INTC, and to consider the possibilities
and options for a future nuclear physics and astrophysics programme at CERN.

4.     DISCUSSION ON THE OPEN SESSION

 

The Committee acknowledged the very good technical progress achieved at ISOLDE during the shutdown, and took note
of the future completion of the radioactive class A laboratory and of the extension of the experimental hall. The news of
the grant awarded to the ISOLDE RFQ project by the British funding agency were received with satisfaction. Many experiments
will benefit from this development.

 

The Committee examined the conditions for the 2005 ISOLDE schedule, and stressed the importance of the beam development
at REX-ISOLDE. The Committee stated that the proton intensity factor should be taken into account by the Scientific
Coordinator when allocating shifts for the 2005 campaign. Experiments in the limit of feasibility and of high scientific impact
should be scheduled with priority. The INTC encouraged the ISOLDE technical team to investigate the possibility of running
experiments in parallel in the ISOLDE hall. The proposals and addenda presented during the open session were then discussed.

 

P111 CERN-INTC-2005-014/P111 Add. 1) Search for new physics in beta-neutrino correlations using
trapped ions and a retardation spectrometer

 

This experiment aims at the determination of bn correlations in order to investigate the possible contribution of tensor and
scalar components in the weak interaction with a precision of the order of 0.5%. After the installation of the WITCH setup
and the preparation phase, the addendum presents a status report and the request to become a fully approved experiment.
The scientific case was judged of the highest interest by the Committee and the installation period successful. The instrument
still needs improvements and adjustments with stable beams, but a proper test of the recoiling ions into the spectrometer can
only be achieved with radioactive species. A total of 18
radioactive beam shifts were recommended for approval by the
Research Board for this purpose. The Committee urged the proponents to accomplish the necessary tests with stable beam
and to install the large MCP detector at the end of the retardation spectrometer before the measurements.

 

 

P132 CERN-INTC-2005-016/P132 Add. 1) Studies of colossal magnetoresistive oxides with radioactive isotopes

 

This addendum intends to continue the investigations of colossal magnetoresistive oxides employing radioactive probes from
ISOLDE. The Committee judged the physics case of the highest quality, with special emphasis on the study of polaron dynamics
and correlations, and on the investigation of the mechanisms associated with the isotopic effect of 18O versus 16O.
The study of local distortions related to charge ordering, and the effect of order/disorder at A sites in perovskites were
considered to be on a less well-established basis, but with enough interest to be pursued. The proposed tests of the local
environment in “multiferroic” materials were seen to be in a very early stage but with certain interest. The proposed investigation
of local defects in HfO2 thin films using 181Hf probe was considered highly attractive, but outside the scope of this addendum.
The proponents are encouraged to come up with a separate proposal on this matter.

The collaboration was judged to be large enough to accomplish the proposed experiments satisfactorily and to achieve a very good
characterization of the samples. The Committee encouraged the proponents to systematically use TEM to characterize all
the samples before implantation. The Committee also noted that the outcome in terms of scientific publications is too poor, and
expressed its strongest concern on this issue, urging the collaboration to revise their publication policy. The Committee
recommended
a total of 27 shifts, including 5 for tests, for approval by the Research Board.

 

 

P171 CERN-INTC-2005-017/P171 Add. 1) Measurement of gas and volatile elements production cross section in
a molten lead-bismuth target

 

This proposal intends the continuation of the measurements of the production of gas and volatile elements from a liquid PbBi
target similar to that of the Megapie project at PSI, in order to understand the amount of radioactivity released. It is proposed
to measure at a different energy than those stated in the original proposal, namely at 600 MeV, which is closer to the operation
energy of 575 MeV of Megapie. Furthermore the proponents would like to measure the ion source efficiency in order to assess
the main source of systematic errors. The Committee supported the scientific case, and specially the measurement at low energy,
but expressed its concern about the suitability of the measurements for the Megapie experiment at PSI, given the expected
precision of the measurements to be not better than 30%. It also questioned the possibility of scaling from the ISOLDE
target to the larger spallation target at PSI. The impact of the outcome of the experiment into the MEGAPIE project was
also questioned due to the foreseen installation already in 2005. It was noted that the run is very difficult to schedule in conjunction
with other runs and that the switchover to 600 MeV requires 2 days of setting up at the PSB and 1 extra day to return
to the standard operation. Conditioned to the technical issues and the possibility of implementation of this scheme,
the Committee decided to recommend 8 shifts
for approval by the Research Board.

 

 

P191 CERN-INTC-2005-001/P191) A study of the r-process path nuclides, 137Sb, 138Sb, 139Sb using the enhanced
selectivity of resonance ionization laser ionization

 

The proposal aims at the investigation of the decay properties of neutron-rich Sb isotopes relevant for the r-process.
The understanding of the r-process is considered to be one of the most significant questions in nuclear astrophysics,
and this experiment on Sb has only become possible recently due to the availability of a laser ionization scheme
with the ISOLDE RILIS. The Committee considered the proposal of the highest interest and expected that the measurement,
and in particular the Pn value, will help clarify the deviations between then observed abundances of isotopes around A=138
and the predictions of r-process calculations. Nevertheless it emphasized that a more efficient use of the beam time should be
sought, both from the point of view of a possible combination of the experimental setups and by exploring the possibility of a
fast flipping of the beam between two ISOLDE beamlines. The Committee recommended
the 9 shifts requested for 2005
for approval by the Research Board. A decision on the reminder of the requested shifts was delayed awaiting a report
by the proponents to the Committee at the end of the year.

 

 

P192 CERN-INTC-2005-003/P192) Elastic scattering and fusion studies in the reactions 10,11Be+64Zn

 

The proposal focuses on the effects of the structure of halo nuclei in the mechanism of reactions below the Coulomb barrier,
where an enhancement of the sub-barrier fusion may occur. The proposal aims at the measurement of the elastic scattering
and the fusion excitation functions for the reactions 10Be+64Zn and 11Be+64Zn. The physics case was judged as extremely
compelling, especially the possibility of addressing this problem with a 2 body halo system, in comparison to previous studies
with the 3-body halo nucleus 6He. The experimental method was judged suitable, and the simultaneous measurement of the
elastic channel very important for the calculations. Nevertheless, the Committee thought that the issue of the beam contamination
should be studied prior to the experiment and stressed that the beam should be monitored online during the data taking.
The Committee decided to support 6 shifts for evaluation of the beam components with 11Be and 10Be beams from REX-ISOLDE,
to be computed under machine development time. While supporting the physics case, the decision on the recommendation
of this proposal was delayed
until a report on these tests is provided.

 

P193 CERN-INTC-2005-004/P193) Coulomb excitation of odd-mass and odd-odd Cu isotopes Using REX-ISOLDE
and Miniball

 

The proposal aims at the study of the properties of the odd-mass and the odd-odd neutron-rich Cu nuclei by means
of the Coulomb excitation technique at REX-ISOLDE. It makes use of the selectivity of the RILIS ion source at ISOLDE
to separate isomeric beams and eventually accelerate them. The scientific case was considered very compelling, with the possibility
of investigating the interplay of single particle and collective effects and measuring effective proton and neutron charges in the
vicinity of the N=40 gap. Especially the measurement of odd-odd Cu isotopes by using prepared states selected by RILIS
was seen as highly attractive. As it was thought that the experiment could benefit from the increased proton intensity available
in 2005 the Committee decided to recommend
for approval by the Research Board a total of 29 shifts, 20 for measurements
and 9 for beam tuning and laser scans.

 

 

P195 CERN-INTC-2005-009/P195) High accuracy mass measurement of the halo nuclides 12,14Be

 

The proposal intends the measurement of the masses of 12Be and 14Be with an accuracy of 10 keV, with the aim of improving
the precision of the 2 neutron separation energy in order to achieve a better understanding of the ground state structure of the
2 neutron halo nucleus 14Be. The proposal was though to be well motivated and of scientific interest, with MISTRAL being
at ISOLDE and it being the only setup capable of such a measurement of the mass of 14Be with a half life of 4.5 ms. It was
noted that the improved transmission by a factor 100 with the new beam cooler system is really required for a successful
measurement. As no beamtime for online tests is requested, it was stressed that the offline tests should prove successful prior
to the experiment. With this provision the Committee decided to recommend 22 shifts
for approval by the Research Board.

 

 

P196 CERN-INTC-2005-013/P196) Precision measurement of the half-life and the b-decay Q value of the superallowed
0+→ 0+
b-decay of 38Ca

 

The proposal intends to contribute to the tests of the conserved vector current CVC) hypothesis by determining the Át value
of the superallowed 0+→ 0+
b-decay of 38Ca. Accurate measurements of the half life, the 0+→ 0+ branching ratio and the
Q value of the decay are required. The proponents intend to perform a high-precision study of the 38Ca half life and a precise
measurement of the Q
b value. The Committee judged the physics case of the highest importance and remarked the need of
the measurement of the three required experimental quantities. It also expressed its concern about the difficulty of the
measurement of the branching ratio. Furthermore, doubts were cast on the feasibility of a precise half life measurement in this
case with the required precision of 0.1
%, given the similarity of the lifetimes of the mother and daughter activities 440 and 925 ms).
Therefore the Committee decided to recommend 5 shifts
for the determination of the Qb value and requested the
proponents to address the measurement of half life and the branching ratio in an addendum submitted to the Committee.

 

 

5.     DISCUSSION ON ADDENDUM TO P156

 

P156 CERN-INTC-2005-007/P156 Add. 2) Coulomb excitation of neutron-rich A~140 nuclei

 

The physics case for this experiment had already been positively evaluated by the Committee. The addendum comes in reply
to the request of a preliminary analysis of the data on 122Cd and 124Cd and the examination of the data on isotope shifts in
the region. This has been satisfactorily done, although difficulties to achieve the expected 10% precision on the BE2) values
cannot be excluded. The Committee decided to recommend
approval of 15 shifts to perform the measurements on the 138,140,142,144Xe
and account for the all the preparations and the involved beam changes at REX-ISOLDE. The Committee also encouraged the development
of the Ba beams subject to the availability of beam development time at ISOLDE.

 

 

6.     LETTERS OF INTENT

 

Letter of Intent: Decay study of neutron-rich At isotopes with a chemically selective negative ion source
CERN-INTC-2005-002/I055)

 

Letter of Intent CERN-INTC-2005-012/I059): Precision measurement of the half-life, of non-analogue branches
and of the
b-decay Q value of the superallowed 0+ -> 0+ b-decay of 70Br

 

Both letters of intent request the development of a negative ion source. While the physics case for the letter I59 was considered
convincing and on the same footing as the proposal P196 discussed above, the physical basis for the letter of intent I55 was
questioned, as the octupole vibrational character of the even Rn isotopes neighbouring the proposed odd isotopes has
already been determined. Therefore the Committee showed its support for the letter of intent I59 and but not for I55.
The Committee considered that the development of a negative ion source will open up new possibilities for the science
at ISOLDE and strongly encouraged its development in the benefit of the physics programme.

 

 

Letter of intent CERN-INTC-2005-008/I057): In-source laser spectroscopy of Po

 

This letter of intent asks for the development and test of RILIS ionisation schemes for Po, as a first step for future measurements
of the isotope shifts and magnetic moments of n-deficient Po isotopes. Since there are no stable Po isotopes, it is requested to do
the tests online with short-lived isotopes and the RILIS, and to check the production of exotic Po. The Committee supported
the development conditioned to the availability of resources and the feasibility to schedule those tests.

 

 


Letter of intent CERN-INTC-2005-010/I058): Low-energy Coulomb excitation of 78,80,82Ge with REX-ISOLDE
and Miniball

 

This letter of intent requests the development of pure Ge beams by using GeS molecular sidebands in order to perform
Coulomb excitation studies of neutron rich Ge isotopes at REX-ISOLDE. The Committee judged the physics case of the
greatest importance, took note of the letter of intent and encouraged the proponents to make a full proposal. The tests should
be part of the beam development time and should be subject to the availability of resources and the target development priorities.

 

 

7.     A.O.B.

 

The next INTC meeting will take place on Monday 23 and Tuesday 24 May 2005. The deadline for submission
of proposals is Friday 22 April 2005
.

The remaining INTC meeting in 2005 will take place in 31 October and 1 November 2005.

Luis M. Fraile
Tel. 73809 - 160985
Luis.Fraile@cern.ch