Minutes of the 39th Machine-Time Committee Meeting
Date and time: December 17, 2010; 13:30–16:00
Place: Nishina Bldg., Room 201
Attendees: Sakai a (Chair), En’yo a, †, Fukunishi a, Kamigaito a, Kase a, Ohnishi a (on behalf of Kubo), Sakurai a,Shimoura b, Ueno a, Uwamino a, Wakasugi aAbsent: Abe a, Kambara a, †, Kubo a, Kubono b, Morita a, Motobayashi a, †, Teranishi c, †, Yoshida a, †a

RNC / b CNS / c UEC / † observer(in no particular order)

Reports
1. Status reports on beam-time (BT) operationz

Accelerator status report (Fukunishi)¾Major problems occurring during the 48Ca beam series of BigRIPS-based experiments thisautumn were reported.

¾

Introduction of the numerical expression for the reliability of beam deliveries was explained.
Reliabilities were deduced for each beam series of BigRIPS-based experiments conductedduring this fiscal year. Except for the 48Ca series this autumn, the reliabilities were better than80 %.

¾

It was suggested that to assure greater reliability, beam delivery should be automaticallysuspended for tuning by the accelerator group whenever there are problems with beamtransmission, even when users do not request such tuning (Kamigaito).

zBigRIPS report (Ohnishi)¾

The total beam dose was 983 pnA•day during the 48Ca beam series this autumn. This is muchsmaller than the 4900 pnA•day, which, it was feared, might hamper on-site radiation-related
work on BigRIPS.

¾

The technique for the production and the isotope-separation of secondary beams has been
improved so that it takes just 2-3 hours, and to adjust the BigRIPS separator to a secondary
beam for which operation parameters are known, only 0.5-1.5 hours.

¾A list of 24 secondary beams produced in the 48Ca beam series was shown.

¾A request was made that the BigRIPS team consider whether it will be possible to allocate 48Ca
BTs in the first half of fiscal 2011 without hindering the scheduled on-site radiation-related
work on BigRIPS (Sakai).

zReport on the 48Ca series (Sakurai)¾Studies of nuclei far from the stability line based on the in-beam γ-ray spectroscopy, which had
been discussed since 2006, were conducted for the first time in this 48Ca series.

¾

As an example, statistics overwhelmingly exceeding those of previous research were obtainedin the study of a 42Si nucleus.

2. BT schedule changes (Sakai)
zThe BTs for the 48Ca series were changed due to beam trouble and ion-source depletion. The series
was finally extended for three days. The comparison of the time lengths between the originallyplanned BTs and actually conducted ones were summarized in the following table.

zExp. Program

Spokesperson

Planned BT (days)

Actual BT (days)

NP0702-RIBF32

H. Scheit

9.5

3.2

NP0702-RIBF28S. Takeuchi

63.7

NP0802-RIBF55

T. Nakamura

4.5

4.5

NP0906-RIBF02

D. Bazin

44

NP0906-RIBF03

P. Fallon

3 (+3conditional)

1NP0912-RIBF33

M. Takechi

64NP0702-RIBF11

S. Nishimura

2 (parasitic)done

Due to the effect of the above noted 3-day delay of the 48Ca series, the BT of ML0702-RRC03(Yoshida et al., 58Fe beam, RILAC-RRC-RIPS) scheduled just after the series was also delayed forthree days and the BT length was reduced by 0.5 days from 6 to 5.5 days.

3. Accelerator machine study reports (Kamigaito)
It was reported that the following MSs were recently carried out.
zMS10-7 [ Spokesperson: A. Goto, BT: 11/26/9:00-11/27/9:00 (1 day),Course: E7, Beam: 6Li, E/A = 11.2 MeV, I = 2 pμA]z

MS10-8 [ Spokesperson: A. Goto, MT: 12/6/17:00-12/6/21:00 (4 hours),
Course: E7, Beam: 6Li, E/A = 11.2 MeV, I = 2 pμA]

4. Status of the PAC meetings (Ueno)z

8th NP-PAC¾z

The PAC meeting was held Dec. 3-5 as scheduled. The PAC is now making a report.

7th ML-PAC¾The PAC meeting is scheduled for Jan. 11-12, 2011.

¾

The call-for-proposals was closed on Dec. 6. There were 21 proposals using the RAL and 3
programs proposed for the RIBF facilities.

¾

In compliance with the decision made in the previous MT Committee meeting, an in-house
technical review is now being conducted for RIBF-related proposals.

¾z

A PAC meeting program is under consideration by the ML-PAC secretariat.

3rd In-PAC¾

The PAC meeting scheduled for January will be skipped.

Topics discussed
1. Approval of the minutes of the 38th meeting (Sakai)
2. Determination of the remaining BTs for the 48Ca series (Sakai)z

Actually conducted BTs are listed in the above table.

z

The MT Committee chair will determine the remaining BTs through individual discussions with therespective spokespersons.

3. Unplanned RI-beam production during BigRIPS-based experiments (Sakai)
It was reported that users often requested the production of additional unplanned secondary beams. In
such cases, safety issues are not reviewed by the Safety Committee, which should be done prior to beamtime on the basis of an Accelerator Use Planning Sheet. The MT Committee decided to deal with such
requests as follows.
zFirst of all, the representative should obtain the approval of the Safety Committee chair. The MTCommittee chair will decide whether or not to approve the request, and will deny the request if anadditional secondary beam would clearly interfere with other approved experimental programs(En’yo).

z

If the representative has any complaints regarding the decision, appeal should be made to the RNC
deputy director who is in charge of supervising RIBF research (En’yo).

4. Formulation of a guideline for BigRIPS-based experiments (Sakai)z

A guideline will be formulated for the smooth operation of BigRIPS-based experiments.

z

The MT Committee chair will discuss provisions for the guideline individually with the user group,
the accelerator group, and the BigRIPS team.

5. Parasite BTs with BigRIPS (Sakai)z

It was proposed that some of the BigRIPS experiments, which can be conducted strategically in aparasitic BT, should be categorized as RNC projects that do not require a PAC review (Sakai). Thiswas countered by a proposal that such projects should still be reviewed by the PAC on the condition
that there is no limitation of primary beams (and also BT length, if necessary) and that there is alsoparasitic BigRIPS use (En’yo).

z

The MT Committee encourages parasitic BT allocation with BigRIPS. How to manage parasitic
experiments and their BT allocation remains under discussion. This issue will also be discussed inother meetings.

6. Conditionally allocated BT (Ueno)zPermission was given to conduct the BT of the DD10-2 experiment (Michimasa et al., α beam at E/A= 6.5 MeV with the E7b course on Jan. 22-24), which had been tentatively allocated on the condition
that the RILAC2 construction remains on schedule.

7. Coming FY2011 first half-year BT allocation (Sakai)zExperimental programs approved by PAC higher than grade A (S, S/A, and A) will be given priority
in the BT allocation.

z

It will be announced in the next Call-for-BT-Scheduling-Requests that the primary beams of 124Xe

and light ions will be available for BigRIPS-based experiments (the possibilities for 136Xe, 70Zn, andKr are also under discussion). Their beam currents might, however, be lower than those announced
in past PAC meetings, since the delivery system for these new beams is still under development.
8. Next MT Committee meetingz

The next MT Committee meeting will be held on Friday, January 21, 2011, from 13:30 to 15:00.

z

The meeting after the next, originally scheduled for February 18, has been changed to February 25,
2011, from 13:30 to 15:00.