CERN/INTC 2000-035

INTC 5

9 October 20
 

 
ISOLDE AND NEUTRON TIME-OF-FLIGHT
EXPERIMENTS COMMITTEE INTC)

Minutes of the Fifth Meeting on
Monday 25 September, 2000




OPEN SESSION

The Chairman opened the meeting with a few brief words of welcome, after which M. Lindroos/PS, discussed the present technical status of the ISOLDE facility. He reported that the HRS front-endwas successfully installed in week 20, achieving a resolution M/DeltaM = 4200 ± 400 and that the first experiment was done with it in week 22. However, mechanical problems with the extraction electode subsequently caused the cancellation of the next UC target) run. A recent contamination incident has resulted in a revision of the radiationsafety status of ISOLDE. A two-year plan will require the target area being treated as a 'class A' area and the experimental area as a 'class C' area. Furthermore a spare front-end is expected within the next year and a new generation of front-ends within a three-year consolidation period. M. Lindroos also described briefly the status of the neutron converter and other targets.

T. Nilsson then presented a status report on the ISOLDE scientific programme. So far 185 experimental and 25 test shifts of radioactive ion beams have been delivered. The General Purpose Separator and PSBooster have been stable and the target performance good. On the otherhand, in addition to the HRS problem mentioned above, a CeO target run has had to be cancelled owing to technical problems with the robot. A further 120 RIB beam shifts are nevertheless expected on the GPS before the end of 2000, and 50 additional HRS shiftsare also scheduled. A test of 600 MeV PS Booster operation is being discussed which may benefit several experiments through increased yields for some isotopes.

E. Radermacher then presented a Status Report for the nTOFfacility. The nTOF was ready to run on August 2, but reliability questions about the target water cooling systems and target remote handling were raised by TIS. There quisite modifications are under way and the first beam is now expected at the end of October.

P. Pavlopoulos, presenting the scientific status of the nTOF, pointed out that in measuring neutron cross-sections its general aims are threefold:

1) a better understanding of Stellar Nucleosynthesis,

2) applications in nuclear technology and Dosimetry,

3) studies of nuclear physics and neutron properties.

He outlined the status of both the already submitted proposals, and those expected up to the September 2001 session of the INTC. An integrated intensity of 2x1019 protons on target per year is the eventual aim. He indicated in addition that a TDR providing a detailed description of the experimental hall and equipment, as well as a plan for the construction of these, will be submitted tothe INTC for its next session. Concerning questions about the responsibilities for individual experiments,
C. Détraz pointed out that the nTOF is intended to become a general facility, and that spokesmen will eventually
designated for each experiment carried out on it.

D. Habs then presented a report on the status and perspectives of the REX-ISOLDE facility, first describing the situation concerning various components of the accelerator and then the tests of theGe miniball detectors, PPAC etc. that have been taking place in Cologne.
A first test experiment at ISOLDE is now expected between 20 November and 25 November this year. This will be devoted to measuring charge breeding yields for ions and molecules and to light mass RIB intensities, but will also include beam, target and detector tests.

A presentation was then made of the proposal:

P130 INTC 2000-029): Measurement of Moments and Radii of Light Nuclei by Collinear Fast-Beam Laser
                                         Spectroscopy and ß-NMR Spectroscopy.

CLOSED SESSION

Present:     B.W. Allardyce, J. Aystö, C. Détraz, J. Eades Secretary), H. Flocard Chairman), K-L. Kratz, M. Lindroos,
                 T. Nilsson, J-P. Riunaud, B. Rubio, W. Scobel, R. Voss, P. Walker, K. P. Lieb, K. Langanke, E. Migneco.

Apologies: H. Ravn, P. van Isacker, C. Rossi-Alvarez, J-P. Duraud.

The minutes of the fourth meeting were first approved with the exception of the typographical error that made 1:6000
appear as 16000 in discussions concerning the HRS resolution.

The Committee first discussed the various technical and scientific progress reports as follows:

1. nTOF Technical Report

The Committee took note of the situation reported by E. Radermacher in his open meeting presentation and hopes
that in spite of the delay related to CERN TIS division's reliability concerns, full commissioning and calibration of
the nTOF facility will be possible this year.

2. External Referee's Report on nTOF TDR

Following the last meeting, the external referee, G. Bauer, had prepared a list of questions concerning this report.
His conclusion was that the collaboration had been very cooperative in answering these, and that the nTOF would
certainly work at the intensity required forproposed and forthcoming experiments during the next year at least.
Nevertheless he felt that there was still a need for a single coherent document giving a complete description of the
facility, rather than the collection ofreports and papers presented in support of the TDR CERN/INTC/2000-004,
11 February 2000). The Committee therefore accepts the TDR with the proviso that such an overall document be
presented during the course of the next year. C. Détraz also pointed out that this approval represents a milestone
for the nTOF, since it is now well on theway to becoming a general facility. This means that the responsibility
for operations up to a suitable point before the detector area willshortly fall on CERN. The INTC will from that
time onward concentrate on questions concerning the experimental proposals.

3. Referee's Review of nTOF Proposals

This concerned mainly the experimental proposal P123 Determination of the neutron fluence, the beam characteristics
and the backgrounds at the CERN-PS TOF Facility) presented in the February meeting regarding the commissioning of
the nTOF. The Committee had then requested further details on the planning and implementation of these studies.
W. Scobel has had extensivecontacts with the nTOF group. The delay of the nTOF commissioning previously scheduled
for June/July has provoked somerethinking and a full TDR on the experimental hall and the experimental apparatus is now
eagerly awaited by the INTC. In the meantime, W. Scobel will raise with the nTOF group the questions outlined in his review.
It is clear that closely related questions concerning proposal P124 The importance of 22Nea,n)25Mg as s-process neutron
source and the s-process thermometer 151Sm., discussed in the May meeting) may usefully be addressed at the same time.

4. ISOLDE Technical Report

The Committee took note of the points raised in M. Lindroos'report, especially concerning the need for a spare front-end
immediately and for a new generation of front-ends over a three year timescale.

5. ISOLDE Scientific Report

The Committee noted with satisfaction that the number of shifts delivered to the experiments this year is already equal to the
number delivered during the whole of last year, and that 50 additional HRS shifts areplanned. The Committee also strongly
supports the proposed tests with 600 MeV Booster energy, although it understood that 600 MeV operation, if successful,  can only be done when the Booster is reserved for ISOLDE alone.

6. REX ISOLDE Report on Status and Perspectives

The Committee took note of the progress made on REX-ISOLDEand looks forward to seeing results of the expected
November and winter tests by the February meeting.

The presentation of proposal P130 Measurement of Moments and Radii of Light Nuclei by Collinear Fast-Beam Laser
Spectroscopy and ß-NMR Spectroscopy) was then discussed. The Committee agreed on the importance of the Ne and Li studies.
It therefore will recommend to the Research Board that the 30 RIB and 15 stable beam shifts be allocated fort hese studies.
However, the case for the Ar studies was notthought to have been demonstrated in a convincing manner yet, and will not
therefore be supported.

Following the Committee's earlier criticism of P85 Add 1 Investigations of deep-level Fe-centres in silicon by Mössbauer spectroscopy), the authors have submitted a revised addendum Investigations of deep-level Fe-centres in silicon
by Mössbauer spectroscopy; INTC 2000-031/P85 Add 2). This has convinced the Committee that the proposed studies will clarify an important process that may be used in semiconductor technology, and will recommend the 10-shift allocation
of beam time to the Research Board.
 

OTHER BUSINESS

P87 Add 1 Letter M. Hass, Spokesman IS303 - proposals 91-11/P8 and 96-31/P87):

This was one of the backlogged experiments IS303) discussed in a previous meeting of the INTC. As the group now
expects to bring to CERN the superconducting cryostat that was causing the delay, and to provide the manpower to test
it during the winter, it was feltthat the outstanding shifts can be reallocated, provided that theexperiment is finished
next year as promised.

The next INTC meeting is on Monday, November 27, for which the deadline for submission of proposals
will be Friday, November 3, 2000.

The dates of the INTC meetings for 2001 are:

February, 26-27

April 23-24

September 24-25

November, 26-27.
 

John Eades
Scientific Secretary; tel. 76 74273
John.Eades@cern.ch

 

INTC Secretariat: Monique Budel Bldg. 14/4-022); Tel. 76 74270
                             Monique.Budel@cern.ch