Minutes of the 55th Machine-Time Committee Meeting
Date and time: May 18, 2012; 13:30–15:00
Place: RIBF Bldg., Room 203
Attendees: Sakaia(Chair), En’yo

Nishimuraa, †a, †ba, Fukunishi , Haba, Shimoura , Sudac, †, ‡a, †aaa, Kamigaito , Kase , Kubo , Motobayashi

aaa, Ueno , Uesaka , Wakasugi , YamaguchiaAbsent: Abe a, Morita a, Sakurai , Uwamino a, Yoshidaa

RNC /a, †,ba, †b

CNS /cRIBF-UEC /†Observer /‡TV Attendee(in random order)
Reports
1.

Status of beam-time operation (Ueno)
A series of the BigRIPS-based experiments using 48Ca beam was scheduled for a month in May. In themiddle of the series however, the ion source showed a sign of 48Ca rod depletion . Thus, the runningbeam time (BT) was suspended to have the rod replaced by a new one . The re-acceleration of the beam
will start soon after baking. Due to the suspension, the BT schedule was modified as follows:
Experimental-Program-Number

previouschanged

SRC:
NP1106-SAMURAI04-01 (Orr) +NP1106-SAMURAI02-01 (Kondo)
NP1106-SHARAQ04-01 (Uesaka)(May/14/21:00 – May/17/14:00 + )(May/14/21:00 – May/17/14:00 + )May/17/14:00 – May/18/21:00 +May/19/9:00 – May/22/9:00→

May/22/21:00 – May/30/9:00→

May/24/9:00 – May/25/9:00 +May/28/21:00 – Jun/4/9:00

Jun/8/9:00 – Jun/11/9:00→

canceled

May/25/9:00 – May/28/9:00

fRC:
MS-ACC12-03 (Imao)
RRC:
ML1006-RRC24-03 (Kuboyama)

May/31/09:00 – Jun/1/21:00(RILAC injection)→

May/20/21:00 – May/21/9:00(AVF injection)

MS-ACC12-02 (Imao)

Jun/1/21:00 – Jun/5/21:00→

Jun/6/21:00 – Jun/10/21:00

IB0702-RRC01-52 (Abe)ML0901-RRC20-16 (Izumi)

Jun/6/9:00 – Jun/6/20:00→

Jun/5/9:00 – Jun/5/20:00

IB0702-RRC01-53 (Abe)Jun/7/9:00 – Jun/7/14:00→

Jun/6/9:00 – Jun/6/14:00

Jun/2/21:00 – Jun/4/21:00
Jun/9/9:00 – Jul/03/9:00→

Jun/5/09:00 – Jun/7/9:00
Jun/12/9:00 – Jul/03/9:00

May/21/9:00 – May/23/9:00→

May/22/9:00 – May/24/9:00

RILAC standalone
NP0702-LINAC12-16 & 18 (Morita)
AVF standalone
NP1012-AVF12-1 (Ishiyama)

2.

RIBF operation (Fukunishi)
The status of the 48Ca beam delivery to the running BigRIPS-SAMURAI/SHARAQ experiments wasreported. The beam delivery started on May 3 at 21:00 as originally scheduled. As given in the above
Report 1, however, the beam delivery was suspended from 14:02, May 17 to have the ion source rod
replaced and baked. Prior to the suspension, 81.5 hours were spent on accelerator tuning within thescheduled BT of 329 hours, indicating that the beam was delivered for 80.1% of the BT. As for theconsumption rate of 48Ca rods, it is empirically known that the consumption rates can be categorized into
two groups: low consumption rate group of 0.5–1.0 mg/h and high consumption rate group of 1.5–1.7

mg/h. An obtained consumption rate in the current BT series, 1.9 mg/h, can be classified in the highconsumption rate group. The lowest (i.e., most efficient) rate ever achieved was 0.68 mg/h of the MUST2
BT conducted in May, 2010, and the highest rate was 4.2 mg/h of the 48Ca series scheduled in autumn of2010.
3.

Trouble of the CGS system (Kase)CGS
A leakage occurred in an instrument pipe for compressed air of the Co-Generation System (CGS).
To repair the leak, the BT was suspended to allow CGS operation to stop at 16:00 on May 10. The
leakage was caused by the corrosion of the iron part of the pipe. Immediately after the repair, CGS
was restarted at 21:30. Accelerator tuning, including the tuning of SRC, was then conducted. The
beam delivery was already resumed by the next morning.

Absorption refrigerator
In the CGS, the absorption refrigerators produce cooling water for the accelerator devices and the airconditioners by utilizing exhaust heat from a gas turbine. It was reported that two of the fiveabsorption refrigerators installed in the RIBF Accelerator Building were malfunctioning. In thepresent BTs series, the remaining three refrigerators are used for the RIBF operation. In this coming
autumn and winter, however, four of them will be required for the RIBF operation in which 238U
beams will be accelerated because this particular operation mode will consume larger amount ofelectricity.

4.

Status of PAC meetings (Ueno)
11th NP-PAC (June 18–19): A data summary of the proposed experiments was shown. In total, therequested BT of BigRIPS-based experiments is 88.75 days. Prior to the PAC meeting, in-house
technical review (May 9‒21), the follow-up status reports on the conducted BTs (May 11‒31), andthe pre-review paper screening by the PAC (May 22‒June 11) will be conducted.

9th ML-PAC: The PAC meeting schedule is being deliberated to be held sometime in September.

3rd In-PAC: The date of PAC meeting will most probably be fixed on July 2. Proposals to bereviewed by the In-PAC can be received at any time.

Topics discussed
1. Approval of the minutes of the previous meeting (Sakai)
2. Outline of the BT schedule for the second half-year of FY2012 (Sakai)Continuing from the previous meeting, the list of primary beams and the outline of their time
allocations for the second half of FY2012 were discussed for the SRC-based experiments.
Discussions also took place about the total BT of the EURICA series tentatively set for the second
half of FY2012.

It was pointed out that some BTs suffered from the drift of magnetic fields of cyclotrons, inparticular, RRC, which requires frequent change in the magnetic-field setting. Although sufficiently

long tuning time is required to stabilize the magnetic field, the time allocated for these experiments
are not long enough. In the next BT scheduling, more careful consideration will be given toaccelerator tuning time.
3. Tentative two-year primary beam plan for SRC-based experiments
Including 18O, 48Ca, and 124Xe beams scheduled for this spring (also 70Zn has been conditionally scheduled
as an extra beam),–Autumn–Winter 2012:

238U, 124Xe, and light ions (AVF-injection)–Spring 2013:

238–Autumn–Winter 2013:(open)

U, 78Kr, (48Ca)

were announced as a tentative two-year primary beam plan for the SRC-based experiments. Discussions
took place on R&D studies required to ensure the delivery of these beams at a high current with highreliability, and on the difficulties to be solved to deliver other beams. Furthermore, the candidate primarybeams to be delivered from autumn to winter 2013 were discussed. The final two-year plan will bedetermined by the RNC Deputy Director in charge of supervising RIBF researches.
4. ML-PAC meetings and RIBF BT scheduling
Proposals to use RIBF in the field of material and life science are reviewed and approved by the ML-PAC.
Since the dates of the ML-PAC meeting are determined by the availability of the RAL facility, thescheduling conflict between ML-PAC meetings and RIBF BT scheduling has become a serious problem.
The issue was discussed from both short-term and medium/long-term perspectives. The issue willcontinue to be pursued.
5. Next meetings
The next meeting will be held on Friday, June 15, 2012, at 13:30

The meeting after the next will be held on Friday, July 20, 2012, at 13:30