Minutes of the 57th Machine-Time Committee Meeting)Date and time: July 20, 2012; 13:30–15:25
Place: RIBF Bldg., Room 203aaAttendees: Sakai (Chair), Abe , En’yo
Motobayashi

a, †

c †

, Nishimura

Hirayama , , Imao
a

a, †

a

, Fukunishi , Habaa, †, Okuno

a

a, †

a

b

, Shimoura , Sudaa, †, A. Yoshida

Absent: Morita , Sakurai , Uesaka , K. Yoshida

a, †

a

a

a

c †

a

b

, Kamigaito , Kase , Kubo , Miyatake , ,

d, †

a

a

, Ueno , Uwamino , Wakasugi , Yamaguchi ,

a, †

a, †
a

RNC /

b

CNS /

c

KEK /

d

RIBF-UEC /†Observer(in random order)
Reports
1.

Changes of the beam-time schedule (Ueno)
It was reported that the beam-time (BT) schedule in June and July had been changed as follows due to theextension of BigRIPS-based BTs (124Xe and 70Zn beams) and the power saving measures at Wako
campus.
Exp.-Prog.-Num.

previouschanged

SRC:
NP1112-RIBF83-01 (Boutachkov)

Jun 18, 9:00 – Jun 25, 9:00→

Jun 18, 9:00 – Jun 29,0:00

NP1106-RIBF74-01 (Obertelli)
NP0811-RIBF70R1-01 (Doornenbal)

Jun 25, 21:00 – Jun 27, 21:00→
Jun 28, 9:00 – Jul 2, 9:00

Jun 30, 0:00 – Jul 5, 12:00

MS-ACC12-05 (Fukunishi)

Jul 3, 9:00

– Jul 8, 9:00→

Jul 5, 12:00 – Jul 8, 12:00

Jun 12, 9:00 – Jul 3, 9:00→

Jun 12, 9:00 – Jul 2, 9:00

– Jul 11, 9:00→

Jul 18, 21:00 – Jul 20, 21:00

RILAC standalone:
NP0702-LINAC12-16 (Morita)
AVF standalone:
DD12-01 (Ishibashi)

2.

Jul 9, 9:00

RIBF operation (Fukunishi)124

Xe beam delivery: Trouble occurred in the vacuum system and the charge-stripper system at the

beginning of the 124Xe beam series which took 3 days to recover. The beam current was as high as I
~ 27 pnA. To keep this current, the charge stripper foil was replaced frequently. The beam deliveredwas 78.1% of the user time.
70

Zn beam delivery: The beam acceleration was conducted as a BT in the Machine Study (MS)category, because this is the first 70Zn beam acceleration using SRC. In the subsequent user’s BT,
the beam was delivered at I ~ 80–100 pnA for 91.7% of the BT, indicating high stability of theaccelerator system. The fixed-type charge-stripper system was operated, where five carbon foils
were consumed in total.
In the continuous SRC operation that started from the polarized deuteron beam in February, 2012 up
to the above-mentioned 70Zn beam in July, 2012, the overall beam-delivery ratio was as high as
88.3%. It was noted that beams were delivered for 5,315 hours out of 7,177 hours; the count wasdone by excluding down times due to accelerator trouble from the total BT scheduled from
November, 2008, indicating that beams delivery rate reached 74% in the past few years.
3.

R&D of the He-gas charge-stripping system (Imao)
In the BT of the MS-ACC12-04 (Imao), a performance test of fRC which has been recently modified,
was first conducted with a 238U65+ beam, and the desirable accelerator performance was obtained.
Subsequently, a performance test of the He-gas charge-stripping system was conducted. The stability of
the actual operation was evaluated in the three day continuous runs including a run with a high current
beam at I = 10 eμA for one day. There were no problems observed in the heat load and radioactivity in its
components such as orifice, He gas, and vacuum pumps. In contrast to the rotational charge-stripping
system currently being used that has had a problem with the charge-stripping efficiency due to thedamage of stripper foils, the He-gas charge-stripping system did not show any such problem. In particular,
it was confirmed that the stability of charge-stripping efficiency is one order higher than that of therotational charge-stripping system in terms of the long-term phase stability in the beam acceleration. The
fRC tuning time will be shortened and its transmission efficiency will be improved by introducing the
He-gas charge-stripping system. Preparations for the actual operation in the upcoming autumn willcontinue, during which time some spare parts and components will be supplied and an interlock system
will be installed.

4.

MS for industrial cooperation programs (A. Yoshida)In the BT of MS-EXP12-03, a high-current low-energy 7Be secondary beam was developed using CRIB.
The beam will be implanted into a 50-μm depth in the surface layer of materials as an RI probe in themain experiments. The 7Be secondary beam was produced at E/A = 4 MeV through the p(7Li, 7Be)nreaction using a 7Li primary beam at I = 1 pμA incident on a hydrogen gas target. An obtained production
yield I = 2108 pps can well be reproduced by a cross section given in the literature data, suggesting thatthe radioactivity of 10 kBq can be produced for 1 hour. In the experiment, the hydrogen gas target system
operated stably, and it took just 6 hours to complete procedures for the RI production. It was shown inthis MS that the radioactivity of 7Be (halflife is t1/2 = 57 d）can be produced with CRIB as much as that of22

Na(t1/2 = 2.6 y) produced so far with E6-RIPS. Now, a suitable radioactivity can be chosen based on the

lifetime of the probes depending on the elapsed time to be observed. It was noted that the charge for use
is just 1/5 of the MT using RIPS because CRIB is operated on a standalone mode of AVF.
5.

Status of the BT scheduling for the second half of FY2012 (Ueno)
According to the BT scheduling policy discussed up to the previous meeting, the BT for the second halfof FY2012 (from October 1, 2012 to January 31, 2013 to be precise) will be determined in the following
schedule. The applications for the BT scheduling requests are now being accepted.
–

Jun. 25‒Jul. 2：NP-PAC report to the RNC & CNS directors, its approval by the directors, anddelivery of PAC results to the spokespersons.

–

Jul. 6‒24：Call for BT scheduling requests & detector development BT requests–

Early–Mid of Aug.: A tentative BT schedule by a working group formed under the MT

Committee–

Mid–End of Aug.: Submission deadline of Accelerator-Use Planning Sheet (AUPS)–

Sep. 1–10: Preliminary document screening of AUPS by the In-House Safety Review
Committee

6.

–Sep. 11：In-House Safety Review Committee meeting–

Sep. 21：Approval of BT schedule by the MT Committee

Status of PAC meetings (Ueno)


NP-PAC: 11th NP-PAC meeting was held on June 18–19 as scheduled. Result: “A”-grade approvals
45.75 days / proposed 88.75 days (52% in days). Of which 39.75/82.75 days (48%) were approvedfor BigRIPS-based experiment,. It was announced the 12th NP-PAC will be held on Dec. 10–11.



9th ML-PAC: It was reported in the RNC Coordination Committee Meeting held on June 14 that
more than half of the ML-PAC members had been changed. The schedule of the PAC meeting was
fixed for September 4–5. The call-for-proposals was distributed on July 6.



The PAC meeting schedule is being deliberated to be held in early September.



3rd In-PAC: The meeting was held on July 2 as scheduled. One proposal was accepted.

Topics discussed
1. Approval of the minutes of the previous meeting (Sakai)
2. Review of proposals in the Machine Study category for the second half of FY2012 (Sakai)


KISS R&D (Miyatake)
The BT requests for R&D studies on KISS (KEK Isotope Separation System) in the MS category
carried forward from the previous meeting were reviewed again, where the following three MSs were
proposed:
1) One to two days requested for a measurement of the space-charge effect on theefficiency/selectivity of KISS as a function of the beam current using an 56Fe beam (E/A = 90
MeV, I = 10 pnA).
2) Two days requested for the same measurement as 1) using an 56Fe beam (E/A = 90 MeV, I = 10pnA) or a 58Ni beam (E/A = 63 MeV, I = 10 pnA) by installing an improved new chamber toreduce the plasma effect.
3) Two days requested for the same measurement as 1) using a 124Xe beam (E/A = 10 MeV, I = 10
pnA).
After discussions, 1) and 2) were approved, but 2) was deferred. It was noted from the Accelerator
Group that a beam diagnostics system should be fully equipped to deliver a beam to the E2experimental room

BigRIPS Ion Optics R&D (Kubo)
An MS study of 8 hours was proposed to investigate the following two secondary beamtransportation modes of BigRIPS required to determine a mass of RI of interest through the TOF

measurement.
–

BigRIPS (F5 high-resolution mode) + ZD (standard mode)–

BigRIPS (standard mode) + ZD (high-resolution dispersive mode)

With these modes, an A/q resolution twice as better can be achieved. In this case, for instance, amass resolution A/A ~ 110–6 can be obtained with 40k counts statistics. After discussions, theproposal was approved.
3. Official BTs provided to the BigRIPS-based experiments in June–July (Sakai)
Details of the BT statistics in the experiments using a 124Xe beam conducted from June 18 to July 5 and a
70

Zn beam from July 10 to 13 were reported (Ueno). After discussions, the official BTs provided from thefacility to each experimental program were calculated as follows:–

NP1112-RIBF83-01 (Boutachkov): 6 days–

NP1106-RIBF74-01 (Obertelli): 2 days–

NP0811-RIBF70R1-01 (Doornenbal) : 4 days–

NP1106-RIBF73-01 (Steppenbeck): 3 days

4. Modification of the approved experiments (Sakai)
The following three proposals to modify experimental condition of the approved experiments were
submitted to the RNC directors and the MT Committee chair by the representative of each program. The
director consulted with the MT Committee on part of these requests.


NP1112-SAMURAI08R1 (Otsu): the change of the primary beam was requested.
–The Committee recognized the necessity for the change. The request was approved.

NP0709-RIBF40 (Terashima): i) the change of the primary beam and ii) an additional measurement
at the different beam energy using 30% of the approved BT were requested.
–

Regarding ii), the spokesperson was requested to submit it as a new or updated proposal (En’yo).
Following this request, i) was discussed by the MT Committee. The Committee acknowledged
the necessity to change primary beam, and the request for change was approved. However, theCommittee considered that the originally proposed measurement can be conducted using only
70% of the approved BT. The BT was, therefore, reduced to 4 days by cutting back 30% of MT.
There was a comment from the Accelerator Group suggesting that the beam energy proposed inii) has not yet been tested (Kamigaito).

NP0906-RIBF03 (Fallon): i) the change of the secondary beam and ii) measurement through adifferent reaction path using the modified secondary beam were requested.
–

The Committee recognized the necessity and the validity of the requests, and approved.

5. Experiments waiting for beam developments (Sakai)
The experimental programs proposing to use the beam not given in the available beam list have been put
on hold for a long time. Most of them had already been approved prior to the introduction of the in-house
technical review where the feasibility of the requested beams was checked. This situation could not beeasily improved due to a long-term BT currently running, where the ion source is always in operation, andman power for beam developments is limited. Moreover, the priority of the beams to be developed mostly
depends on the research strategy of RNC. The beam development is thus not always conducted according
to the users’ request. A beam-development plan and its timeline will be announced to the spokespersons
concerned after they are made more clear.
6. Next meetingsThe meeting will be held on Friday, September 21, 2012, at 13:30 (it will be adjourned during
August unless an extraordinary meeting is convened.)

The meeting after the next will be held on Friday, October 12, 2012, at 13:00