THE INTERNATIONAL ADVISORY COMMITTEE
ON THE J-PARC PROJECTREPORT
Meeting held March 5th - March 6th2018
In the J-PARC research building, Tokai, JapanFirst acceleration of a muon beam at J-PARC

May 20th 2018

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Contents
EXECUTIVE SUMMARY:........................................................................................................................... 4
SUMMARY OF THE RECOMMENDATIONS BY SECTIONS IN THE REPORT ................................................ 5
Management....................................................................................................................................... 5
Safety .................................................................................................................................................. 5
Accelerators ........................................................................................................................................ 5
Particle and Nuclear Physics ................................................................................................................ 5
Material and Life Science Facilities: ..................................................................................................... 6
MUSE Facility: ..................................................................................................................................... 6
TEF (transmutation Facilities): ............................................................................................................. 6
INTRODUCTION: ............................................................................................................................... 7
GENERAL STATUS OF THE PROJECT: ......................................................................................... 7
SAFETY: ............................................................................................................................................... 8
STATUS OF THE ACCELERATOR SYSTEMS: ............................................................................................... 9
SCIENTIFIC PROGRAMS:........................................................................................................................ 10
MATERIAL AND LIFE SCIENCES FACILITY (MLF): .................................................................................. 14
MUSE: ............................................................................................................................................... 16
NUCLEAR TRANSMUTATION: ............................................................................................................. 18
INSTITUTIONAL SUPPORT BY JAEA: .................................................................................................... 19
MEXT view of J-PARC: ........................................................................................................................ 19
Conclusions: ........................................................................................................................................ 19
Appendix I ............................................................................................................................................ 21
Agenda for the International Advisory Committee Meeting of J-PARC in 2018 .................................. 21
Appendix II ........................................................................................................................................... 22
Appendix III .......................................................................................................................................... 23

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EXECUTIVE SUMMARY:
The International Advisory Committee of J-PARC (IAC) met March 5th and 6th at J-PARC. The committee
heard presentations from the director, the Safety and Accelerator groups, the scientific groups and theirrespective advisory committee chairs, from representative of MEXT and management of JAEA.
The committee was very pleased to see that the shift in priority to favor a safe, reliable delivery of beamat the expense of pushing the frontier of beam power led to an improved production of interestingscience in all areas. In particular, numerous publications were reported in prestigious journals,
involvement of industry is very high by international standards and Press releases are used tocommunicate the exciting results to the general public. This is all going in the direction favored by the
IAC last year.
The accelerators are showing excellence performances and it is the targets and beam extraction
elements (kicker magnets, electrostatic septum…) that are limiting the beam power. Progress is being
made in developing more reliable targets with help from international expertise but the IAC is still
advocating a conservative approach in commissioning high power systems, both from the point of viewof reliability and dose management. The safety culture of J-PARC has changed and is more and more inline with international standards. The implementation of a stop work order policy is in progress and the
IAC was shown evidence that the number of safety incidents are decreasing while the reporting ofpotential problems is increasing indicating that staff is being more aware of safety issues and willing to
act on them at all levels. The IAC recommends to formalize the reporting along a severity scale so thattrivial issues can be dealt with at the local manager level while more serious breaches are transferred to
J-PARC management for action and further evaluation.

The IAC notes that good progress was also made in bringing key new experiments on the floor (g2/EDM, COMET for ex) while improvements on the MR slow extraction allowed a hyper-nuclear program
to produce new results and lead a world-wide activity in that field. The neutrino program received close
to 500 kW of reliable beam on target and was able to show first evidence for lepton CP violation.
However, the MR program is awaiting anxiously the replacement of the MR magnet power supplies(PS)which would allow to reduce the beam cycle time and hence improve beam intensity and quality.
Funding for the PS is not in place and this compromises the long-term competitiveness of the highenergy program. This is an urgent matter to be addressed so as to keep the international appeal of the
facility and not compromise the scientific reach of the HyperKamiokande(HK) program which was rated
as one of two highest priority items in the MEXT roadmap for large scale frontier projects in high energy
physics.

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SUMMARY OF THE RECOMMENDATIONS BY SECTIONS IN THE REPORTManagement
SafetyRecommendation:“Stop Work”: Prepare written guidelines about when the situation can easily becorrected and work resumption can be authorized by the work site manager (e.g.
missing PPE) or when an investigation is required (e.g. unsafe behavior or nearmiss) and work needs to be reauthorized by management.
Accelerators•

Recommendation:
Explore opportunities to reduce the time spent on machine start-up and beamtuning•

Implement the MR fast extracted beam power upgrade as soon as possible
Particle and Nuclear Physics• Neutrino
Recommendation:
The MR power supplies upgrade requires an urgent firm commitment and time tableas part of a global strategy to increase the number of proton on the neutrino target tofirmly establish CP violation in the lepton sector.
•

Kaon Physics

Recommendation:
The IAC looks forward to a prompt publication of the analyses of E36 and KOTO’s
2015 data• MuonRecommendation:
After reaching key milestones this past year, both the g-2/EDM and COMET efforts
must be given strong support to compete on a time scale set by the parallel efforts at
FNAL.
•

Hadron facility

Recommendation:

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The IAC recommends to proceed with the construction of the new spare target
assembly for the slow extracted beam program as soon as possible.

Material and Life Science Facilities:
Recommendations:
MLF should prioritize availability for science rather than power level. A disciplined
approach to power ramp-up will result in earlier sustained operation at 1 MW.
MLF should endeavor to determine the bottlenecks from proposal to publication that limit
scientific output.
MLF should further address uneven staffing across the instrument suite by, for example,
pursuing the idea of “public beam time”.

MUSE Facility:
Recommendations:
Since the generation of ultraslow muons is the key issue not only for the USM project on Uline but also for several experiments on H-line, multiple backup plans should be considered
for the case that the Nd:YSAG material is unsuccessful.
The exciting science program planned for the H-line can only be enabled with functioning
H-line which we recommend to be completed with high priority.
TEF (transmutation Facilities):•

Recommendations :•complete the English version of the TDR of TEF-T•

To update the ADS roadmap of JAEA regarding the construction of the TEF-T
facility•

To enlarge the R&D on accelerator reliability which is of paramount importancefor the ADS application

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INTRODUCTION:
The International Advisory Committee (IAC) for J-PARC met on March 5th and 6th at the J-PARC
research building to review the progress and scientific achievements of J-PARC over the past year. The
agenda for the meeting is given in appendix I, the committee’s composition in appendix II and the charge
to the committee n appendix III. A site visit took place in the afternoon of Tuesday March 6th when thecommittee toured the MLF experimental areas, the hadron facility hall including the new extension for the
COMET experiment and the near detector of the T2K neutrino experiment. The committee heard the viewof the MEXT funding agency responsible for most of the support for J-PARC during a presentation by
Dr. Todoroki. Dr. Miura-san reported on the situation at JAEA and how J-PARC fits in its mandate. KEK
director Professor Yamauchi-san was unable to attend due to a last -minute dental emergency.
The committee heard from the advisory committees monitoring specific areas of the complex: theAccelerator Technical Advisory Committee represented by its chairman Dr. T. Roser, the Transmutation
Advisory Committee by the Dr. Maekawa-san, the Neutron and Muon Advisory Committees by theirrespective chairs Dr. Shibayama-san and Dr. F. Pratt.
Safety has been elevated as the overriding priority for all J-PARC activities and the IAC was briefed on
the progress made to institute a global safety culture for all permanent staff, contractual workers and users
by Dr. T. Ishii.

GENERAL STATUS OF THE PROJECT:
Dr. N.Saito reviewed the major accomplishments of the past year. He placed his remarks in the context of
the J-PARC action plan being implemented and showed how he responded to the recommendations madeby the J-PARC IAC last year. The key objective was to provide a safe and stable operation on the way
towards high-power operation, with two priority milestones in terms of beam availability to users andscience output.
By focusing the site priority on beam availability and delivering more than 90% of the scheduled beam toexperiments, many users enjoyed reliable data taking performance at a level which guarantees significant
progress towards their scientific objectives. This was shown by the number of press releases (11) which
publicized new important results and by the number of high level publications.
To increase the scientific output of J-PARC, a concerted effort has been mounted to connect with
Universities, Industries and Institutes worldwide. Four Japanese Universities are creating branches at JPARC focusing on support for students and young researchers, four Memoranda of understanding havebeen signed with foreign institutes and strong partnership with industries have already led to the fundingof special fellowships to support collaborative work ( e. g. Sumimoto Fellowship. ). A notable effort isthe creation of a Science focus group for MLF users aiming at facilitating the extraction of results from7

data collected at the MLF by providing and supporting universal data analysis frameworks. The IAC isstrongly encouraging this effort. It needs strong leadership to succeed.

The IAC applauds the initiative to join the RaDIATE organization which allows all major laboratories
facing radiation damages issues (e.g. target failures) to share their experience and expertise. This isbound to provide solutions to the current limitations in power delivery to the various targets on J-PARC’sfacilities. In parallel a major project to upgrade the capacity of the main ring (MR) power supplies toallow a faster cycling rate is progressing but is limited by available funding and may not be available tousers before JPY 2022. This is part of the intensity upgrade required by most experiments using either
slow or fast extraction from the MR. The IAC is fully in support of the project and recommends that acomprehensive technical document be prepared describing the global efforts needed to increase the beam
power and beam quality to MR users thereby achieving the design goals for J-PARC and to meet therequirements of the user community as expressed in the recent Japan Science Council master plan
document.
At this time, MEXT has started the laboratory review process (which happens every five years). Together
with the development of the Japan Science Council master plan and MEXT ‘s roadmap, this would
provide for a long-term vision for the laboratory. The IAC believes that the laboratory will be able todemonstrate that it is on the path to and already delivers world class science and given adequate resources
could be a world class international attractor for a wider range of scientific researchers.

SAFETY:Management has made continued good progress in implementing all the elements of a safe workplace at
J-PARC, which includes: an established process for safety reviews, a fully developed and broadly
implemented work planning process, a safety culture that allows the staff to speak up about unsafe
behavior of others, called “Mindful of Others”, and a process to “Stop Work” in a potentially unsafe
situation.

The “Stop Work” policy is implemented locally at J-PARC through the work site manager, who then canalso authorize the resumption of work. The Committee congratulates J-PARC management to have founda way to implement the “Stop Work” process even though such a policy is not recognized in Japan.
The number of incidents at J-PARC has been declining over the last few years. At the same time there is apositive indication of improved safety awareness by the staff as the reported number of “near misses” ishas been increasing.
Extensive safety training is being implemented throughout the J-PARC facility. The Committee supports
the plan to train shift leaders in the proper response in emergency situations.

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Recommendations:“Stop Work”: Prepare written guidelines about when the situation can easily be corrected
and work resumption can be authorized by the work site manager (e.g. missing PPE) or
when an investigation is required (e.g. unsafe behavior or near miss) and work needs to bereauthorized by management.

STATUS OF THE ACCELERATOR SYSTEMS:The IAC congratulates the accelerator group on the significant improvements that were made inaccelerator operations and beam delivery during 2017. All parts of the science program
benefitted. Notably:•••

Beam availability to the MLF was better than 90% during 2017. This was accomplishedwhile delivering an average power of 400 kW.
The MR has also operated well with beam availability near 90%. For much of the period,
power for FX was 475 kW and it was up to 50 kW for SX.
Problems with the ESS have been corrected for the SX beam and successful beam
extraction at both 8 and 30 GeV has been accomplished.

It is rather remarkable that the linac was able to operate for three months without an ion sourcechange. This should lead to even more beam availability. As part of a continual effort toimprove efficiency for beam delivery, the accelerator division has worked to lower the time lost
due to beam trips. But the procedure to recover from all trips seems to require humanintervention. There are likely classes of trips that could have automatic recovery systems thatwould not lead to potential machine damage. It would useful to investigate this and implement
automatic recovery where possible.

•

There are many demands on the beams from the accelerators at J-PARC. But science
output is now a primary concern for all of the J-PARC programs, so further improving
beam availability is a priority. The IAC supports the ATAC recommendation to explore
opportunities to reduce the time spent on machine start-up and beam tuning

9Optimizing running time for experiments requires having the accelerators deliver beam to targets
and having the targets support the available beam. Moving forward, the accelerator group needs
to work closely with target groups to optimize the machine performance and availability.
Coordination is needed to determine when to change targets and when to push the beam intensity
on existing targets. For example, plans are now in place to install a new target that should allow
for higher beam power for the MLF. This will be a welcomed development but should be done
carefully so that a target failure does not result in significant down time. Increasing the beam
power on a new target design should be done only if there is a good backup target available incase there is a failure.
For the MR, increasing the beam power to the neutrino program and to the Hadron Hall is very
important but it needs to be done while maintaining beam availability. Plans were discussed for
improving the MR beam power, eventually up to 1.3 MW for the neutrino program. This effort
will need to be done in steps and ultimately will require improvements to power supplies and to
the MR performance. It is crucial that this improvement program get underway, hence the IAC
supports the ATAC recommendation:
As part of the effort to move to higher MR beam power, the IAC recommends that a Design
Report be developed soon that looks at all potential ways for improving MR beam power andmachine performance. The Design Report should at least consider the improvements from faster
cycle time with upgraded power supplies, running with more protons per bunch, and the
reduction of beam loss during the early stage of MR acceleration.

Recommendations:• Explore opportunities to reduce the time spent on machine start-up and beamtuning•

Implement the MR fast extracted beam power upgrade as soon as possible

SCIENTIFIC PROGRAMS:PARTICLE AND NUCLEAR PHYSICS:

Neutrino Physics
The determination of neutrino oscillation is one of the outstanding science achievements of thelast decades. The contribution of J-PARC to this scientific milestone via the T2K experiment
was widely recognized and strengthens its worldwide reputation.

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As the next step, the T2K collaboration aims to firmly establish CP violation, in the lepton
sector, which would certainly be another outstanding achievement. Currently this effect isobserved at the 95% confidence level, but the T2K collaboration feels that it has to be improved
to the 3 sigma level and beyond. To achieve the 3 sigma goal, 20 times 10^21 protons on target
are required. As currently less than 10^21 POT are reached annually, an upgrade program is
proposed that increases the annual POT to about 2-3 10^21. The committee would like to see an
updated time schedule showing how this upgrade program and the data taking with it fits into thegeneral J-PARC planning.
The committee, however, notes that the proposed upgrade plans will have to be reconsidered
once the Japanese government makes a determination of the funding profile for the HyperKamiokande project. A positive decision for Hyper-K would be a complete game changer,
which would open up exciting new perspectives for J-PARC.
In addition to the highly visible CP violation efforts, J-PARC is also running a wider neutrino
physics program. In particular, the E61 experiment aims at measuring neutrino cross sections on
various targets. These data are crucial to reduce uncertainties in the CP violation search.
Furthermore, a dedicated experiment to search for sterile neutrinos is being performed at the
MLF in a parasitic mode (JSNS2 experiment).
The IAC congratulates J-PARC and the T2K collaboration for their worldwide recognizedachievements. The committee strongly endorses the proposed measures to firmly establish CP
violation in the lepton sector.
Recommendation:
The MR power supplies upgrade requires an urgent firm commitment and time table as partof a global strategy to increase the number of proton on the neutrino target to firmly establish
CP violation parameters in the lepton sector.
Kaon Physics
The KOTO experiment is making increment progress towards reaching the Nir-Grossman limit forthe branching ratio KL0àpnn . Significant data accumulated in 2015 are being analyzed with ablind analysis technique and should reveal the extent of background level encountered. It is very
important to complete this analysis as it may dictate the path towards better sensitivity. Meanwhile
improvements in background reduction are being made in the trigger and online processing of thedata and validated by looking at the side-band content. Assuming that no new background sources
are revealed by the analysis of the 2015 data, the experiment requires stable and long beam delivery
at the 100 kW level with controlled beam targeting. The planned upgrade of the MR power supplies
will also be crucial towards that.
E36, a measurement of the lepton universality in the two body decay of K+, has completed its datataking and should provide a measurement of the ratio of branching fractions K+ àen / K+àµn at
a precision less than 1%. This result would be timely as there is renewed theoretical interest in thistype of constraints on extensions of the standard model.
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Recommendation:
The IAC looks forward to a prompt publication of the analyses of E36 and KOTO’s 2015
data
Muon Physics:
Three major efforts are in progress: a new innovative approach for measuring the g-2 and thedipole moment of the muon with very high precision, a study of the muon to electron conversion
at a sensitivity level of 10-14 (in phase 1) with the COMET set up and a muonium spectroscopy
study.
In the MUSE facility, the H line is being built to produce muonium from a muon beam stopped in
an aerogel target, followed by ionization and reacceleration of the resulting low transverse
momentum muons. After demonstrating that a laser ablated aerogel target can enhance themuonium production to satisfactory levels, the g-2/EDM team reached a second milestone withthe recent demonstration of RF acceleration of a muon beam in the D2 line of MUSE (a world
first).
Also cross calibration of the NMR probes from the KEK and FNAL teams demonstrated anagreement within 8 significant digits.
A re-evaluation of the systematic uncertainties was made, confirming previous estimates and a
new international theory initiative has started to provide the necessary theoretical hadronic
corrections ahead of the results of both the KEK and the FNAL experiments.
A revised g-2/EDM Technical Design Report(TDR) was produced to respond to therecommendations of the Program Advisory Committee and the team is now requesting stage 2
approval.
For the COMET effort, a new 8 GeV beam will be delivered from the MR to a new dedicatedtarget facility. Since the measurement takes place in between beam buckets where somebackground is expected from leaking protons, a test measurement was made in the K1.8 beamline
which demonstrated that a better than 10-10 extinction can be obtained, which leads to a sensitivityof the order of 10-14 in the first stage of the experiment. The collaboration has now 182 researchers
from 32 Institutes and is concentrating in delivering the beam transport system and the initialdetectors in the completed new building.

Recommendation:
After reaching key milestones this past year, both the g-2/EDM and COMET efforts must be
given strong support to compete on a time scale set by the parallel efforts at FNAL.
Nuclear Physics
Over the past three years the accumulated beam for slow extracted beam experiments (nuclear
physics and kaon experiments) has increased by an order of magnitude compared to the resultsfrom FY09 to FY14. The power of the slow extracted beam has reached 50% of the design
power and the instantaneous duty factor was increased to about 50%. This has allowed the12research to go beyond initial exploratory studies to the more definitive work for which thefacility was designed.
The observation of the multi-messenger signals from colliding neutron stars highlights theimportance of this research in understanding the properties of high density nuclear matter withstrangeness. A number of approaches predict that strange baryons and mesons should play adefining role in the equation of state of neutron stars, but the uncertainties in the elementary
hyperon-nucleon and meson- nucleon interactions have made the predictive power of current
theories limited. The observation of a clear peak in the K-pp system at a binding energy of about
40 MeV seems to validate a number of the theoretical predictions. The first information on the
structure of the s-d shell hypernucleus, !"#$ , demonstrates that the spin dependence of the Λ&interaction is under control. New substantial data sets for Σ( scattering and strangeness -2
systems are now being analyzed. The expected improvement in the resolution with the S-2S
spectrometer will be very valuable.
It is important for the future that the user community accelerate the stream of impactful
publications from the nuclear physics program. We encourage the laboratory to continue toclosely monitor the progress on all the experiments.
The IAC was pleased to see the PAC has re-examined the science goals and progress of the earlyround of nuclear physics experiments in light of actual performance and updated schedules. Thisshould give the users more realistic expectations for future experiments. Several have been given
stage 2 approval for additional measurements.
Hadron Facility:
The IAC continues to be concerned that the existing slow extraction production target remains asubstantial risk to the nuclear physics, kaon and COMET programs. Another secondary risk is
the lack of a spare extraction septum. The beam delivery group has shown that operation with asingle septum is possible, but with increased beam losses. As elsewhere, the IAC notes that if
beam losses are not reduced, higher power operation will be compromised.
It is essential to have a spare production target available as soon as possible. The existing target
system has two identical production targets in the chamber so that, when the target monitors
indicate some cooling deterioration, the target can be exchanged. We appreciate the work thathas gone into the target upgrade project and urge the lab to give it extremely high priority. A
decision needs to be made to either produce a backup to the existing target or proceed with theconstruction of the new target. If the new target can be produced on a timescale that would allow
it to be the backup, that would be the preferred option. If this cannot be done but a copy of thepresent target can be procured soon, then that option should be considered. It is very risky toplan to run the SX beam with no backup.

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Recommendation: The IAC recommends to proceed with the construction of the new backup target assembly for the slow extracted beam program as soon as possible.
MATERIAL AND LIFE SCIENCES FACILITY (MLF):
MLF - Neutrons
The Materials and Life Facility (MLF) is a world leading research institute for neutron science.
The combination of the proton power on the target, the 25 Hz frame rate, the exceptional designof the moderators, and 20 excellent instruments provide the scientific community in Japan andaround the world an outstanding resource for neutron-based research. Availability is essential
for maximizing the scientific return on the considerable investment Japan has made in neutrons
at J-PARC. Last year the MLF achieved a remarkable 93% availability allowing users to plan
their beam time effectively. The community has taken note with more than 900 scientists
making use of the MLF in FY2017. The IAC is particularly impressed by the 30% of
experiments that involve industrial scientists. Much of the science coming from the MLF is at
the world standard and promises important societal benefits. Of particular note, Toyota will use
a new Li solid electrolyte (Li9.54Si1.74P1.44S11.7Cl0.3) to provide all solid-state Li-ion batteries intheir 2022 electric vehicles thereby reducing the risk of fire. The development of this material
was greatly facilitated by neutron diffraction results from the MLF (Nature Materials (2011) &Nature Energy (2016)).
In spite of the MLF’s considerable achievements, the number of publications remains low byinternational standard. When considering this, it’s important to note that the large industrial
engagement (30%) will significantly reduce the number of open publications. However, there is
still a shortfall. MLF recognizes this and is taking steps to increase the number of experimentsthat turn into publications by revising the reviewing process of user program, enabling moredetailed assessment of proposals, together with unifying BL operation, by the newly establishedneutron science groups within in MLF and increasing interaction with science community ingeneral through the establishment of science promotion board. However, the reason for the
shortfall is still not quite fully understood.
We also note that “solutions” that don’t directly address real bottlenecks will likely distract staff
from actions that might improve the situation. Thus a targeted, evidence-based approach isdefinitely needed. However, it is also essential that staff continue their role in enabling
exceptional science.
The IAC recommends that the MLF should endeavor to determine the bottlenecks fromproposal to publication that limit scientific output.
Although the long term plan for the MLF must include a 2nd target station, the immediatepriority should therefore be on realizing the potential of the considerable investment alreadymade in the MLF.
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Issues with the mercury target including unanticipated failures have limited the productivity of
the MLF. Thus the IAC was pleased to hear that the most recent target (#8) has performed
admirably allowing sustained operation first at 0.3 MW and now at 0.4 MW. In April, it isplanned to go to 0.5 MW. This is excellent progress toward the goal of 1 MW operation. We
were also pleased that target 9, which has the same design as 8, is available in case of unexpected
problems. However we caution that there is still a long way to go before 1MW operation
becomes routine. Thus it is essential that the MLF learn as much as it can from post irradiation
examination (PIE) on each target. This requires careful consideration of how to proceed. To theextent possible, every target should be operated in such a manner as to maximize the usefulnessof the information that can be gained from PIE. In this regard, we note that a limited 1 MW test
on target 8 for the last week before the summer shutdown will unnecessarily complicate theanalysis of the PIE. We also note that target 10 has a different design so the MLF shouldcarefully consider what really can be learned from this short test when the aim must be sustained,
reliable operation.
Recommendation:
The IAC recommends that the MLF should prioritize availability for science rather thanpower level. A disciplined approach to power ramp-up will result in earlier sustained
operation at 1 MW.
In addition, we note that target 10 is not scheduled to arrive until August or September and must
be installed by the end of September. As target 10 has new design, this entails some risk whichis mitigated by having target 9 on hand as a backup with a new proven design. So only if 10 islate, might target 9 be used.
The management environment of the MLF is quite complex with instruments operated by four
different organizations. This leads to inconsistencies in the support that users receive based
solely on the resources of the organization that operates the particular instrument they are using
inevitably leading to frustration. The MLF has recognized this issue and has taken steps such asproviding an integrated proposal system and user portal to address it. They have also worked tobetter engage the community through a variety of steps such as user surveys and the Science
Council. This is a good start, but the heart of the issue remains. The IAC supports theestablishment of the public user beam tine on all MLF lines.

Recommendations:the IAC recommends that the MLF should further address uneven staffing across the
instrument suite by, for example, pursuing the idea of “public beam time”.

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MUSE:

Materials and Life Sciences – Muons
U-lineImpressive progress has been made on all four beamlines, i.e. D, U, S, H-lines and theirassociated instruments. A very significant achievement is the first observation of the muon spinrotation spectrum with ultra-slow muons, which will open a new era for surface and hidden
interface analyses, in February 2018. However, the absolute counting rate is still 2 orders ofmagnitude below that needed for a viable user facility offering USM µ+SR mainly due to the lackof a high quality laser crystal/ceramic rod for final amplification of the beam.
Recommendation
IAC looks forward to hearing about results from the new way of producing Nd:YGAG and
the developments around Nd:YSAG material. Since the generation of ultraslow muons is
the key issue not only for the USM project on U-line but also for several experiments on Hline, multiple backup plans should be considered for the case that the Nd:YSAG material isunsuccessful.

D-lineCreative advances in beam diagnostics enabled a substantial improvement in beam transport ofnegative muons at D line. This enabled implementation of a new collimator system andmeasurement chamber and resulted in demonstration experiments with these new capabilities.
This progress, complementary to standard µSR, is excellent, and it should soon move beyond
demonstration experiments and begin to have impact in other fields. We look forward to highprofile uses of muonic X-ray elemental analysis, positive and negative muons induced single
event upsets diagnosis and negative muon spin rotation and relaxation (µ-SR) technique in the
coming year.

S-line
The first port among the four of the S-line surface muon channel (S1) has now been opened forusers’ program. µSR sample conditions, auto-run program, and on-line monitoring system byusers have been upgraded steadily at the D1 and S1 ports.
Such progress has made MUSE an excellent world-class facility in terms of user interface to theexperiments.

H-lineThe H-line will be the spinal cord of a broad new research program at J-PARC. Its speedy
completion is strongly required and IAC recommends to J-PARC/ KEK management that all
possible means should be taken to realize the H-line and its promising scientific program withhigh priority. We are pleased to learn that the necessary steps were already taken to provide an16additional 4 MW electric power to the experimental hall. We expect that this started
development will be completed within the next couple of years.
Recommendation
The timely completion of the H-line will be important for the scientific success and impact
of experiments like the muonium hyperfine structure, muon g-2/EDM, DeeMe and themuon microscope. All these projects are timely now and have tremendous scientificdiscovery potential. The exciting science program planned for the H-line can only beenabled with functioning H-line which we recommend to be completed with high priority.

Muon production target
The current rotating muon target has operated for 40 months without trouble, making 10M
revolutions out of its full design life of 50M. Work continues on improving the target diagnostics
and developing next generation muon targets using materials such as SiC coated graphite and
SiC composites.

Target Station 2
Working groups of J-PARC MLF division and of the Japanese Society for Neutron Science andthe Society of Muon and Meson Science of Japan were organized to discuss the plans for a futuretarget station 2 in MLF in order to apply Japan Science Council’s Master Plan 2020 (the deadline
is February 2019). This plan includes an upgrade of the proton beam power to 1.5 MW, asplitting of the proton beam in front of the existing MLF hall by a fast magnetic kicker, and thebuilding of a new experimental hall with a combined muon/neutron spallation target.
The extraction of the muons from the entrance window of the spallation target will be achievedby a large acceptance solenoid, and a surface muon beam (or decay muon beam) intensity
increase by a factor of 50-100 compared to the existing muon beams at target station 1 are
expected.
Recommendation
This is a project for the time horizon beyond 2030 and IAC welcomes and encourages these
initial ideas for future large scale muon projects at J-PARC, although more detailed
discussion is necessary for preparing a suitably persuasive conceptual design report (CDR).

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NUCLEAR TRANSMUTATION:
After having heard the reporting of Dr Fujio MAEKAWA , the head of the Nuclear
Transmutation Division of J-PARC on the outcome of the ADS T-TAC meeting held on
February 19-20, 2018 and the progress accomplished on the TEF design program and theassociated R&D support program reported by Dr Toshinobu SASA, the IAC acknowledges the JPARC responses to the 2017 recommendations but recognizes the difficulty for the ADS team toprogress seriously on the realization of TEF facilities until a clear vision is formulated in the
JAEA roadmap.
The IAC acknowledges the enhanced international collaborations on ADS activity within JPARC ADS group and the extension of the scope of activities towards the accelerator reliability
activities.
The IAC acknowledges the progress accomplished by the ADS team on:– The safety report of the TEF-P– The completion of the TEF-T TDR (but unfortunately the English version was notready to be submitted to the T-TAC)
It is now important to establish and evaluate carefully the experimental program of TEF-P loadedwith MA based Fuel in terms need for V&V in an international context where the number of fast
spectrum reactor facilities is being drastically reduced
LBE target technology has been selected as a major subject of TEF-T and intensively studied,other alternative technologies, such as granule target and windowless scheme, may be worthy to
study for providing other option which will be utilized in CiADS.
A number of critical design requirements for ADS activities have a significant overlap with other
J-PARC programs and such synergies should be exploited for example in the accelerator R&D
for reliability issues or in the targetry systems.
Recommendations:–

Complete the English version of the TDR of TEF-T–

update the ADS roadmap of JAEA project in regard to the construction of a
TEF T facility material testing–

enlarge the R&D on accelerator reliability and join the J-PARC accelerator
team in areas where synergies for both teams can be found (SC cavity
development, especially for the low-beta section, Room temperature CW RFQ
linacs)–establish and evaluate carefully the experimental program of TEF-P loadedwith MA based fuel in terms of international need.

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– Examine technologies other than LBE targets such as granule target andwindowless scheme.

INSTITUTIONAL SUPPORT BY JAEA:
Dr. Miura-san reviewed the challenges faced by JAEA which is planning to reduce drastically its
operating facilities (44 out of 89). JAEA is also facing several contamination incidents and isreviewing its safety culture. JAEA views J-PARC as an important component of its mandate andis strongly supporting its operation. JAEA is also in favor a strong Science group to improve thereach of MLF to a large community of both academic and industrial users and pledges to support
the efforts of management to increase user beamtime on all MLF beamlines.
MEXT view of J-PARC:
Dr. Todoroki-san gave an overview of the long-range planning process at MEXT for supporting
large scale scientific projects. It starts with the master plan by the Science Council of Japan
which considers community driven projects. MEXT then establishes a roadmap for a selected
number of projects based upon scientific evaluation, urgency and needs. The top priority project
are then evaluated and submitted to the Ministry of Finance for budget allocation. In the newroad map, two large scale frontier projects in high energy physics were selected: Highluminosity LHC upgrade and HyperKamiokande (HK). The HK proposal is directly linked to the
J-PARC neutrino beam upgrade and requires operation of a 1.3 MW proton beam for at least 10
years once the far detectors are operational. However due to budgetary constrains, it was notpossible to convince MOF to start the funding in this fiscal year.
In parallel, MEXT has initiated the five year review of the laboratory which provides MEXT
with a good evaluation of the performance of the laboratory and gives MEXT ammunition to
defend the importance of the research done by J-PARC to the public of Japan. MEXT wasparticularly sensitive to the publicity generated by the results of the neutrino program ( evidence
for asymmetry in neutrino-antineutrino oscillation) and by the press releases related to MLF
experiments.
Dr, Todoroki pledged to continue to work hard to promote the importance of J-PARC at the
government level as well as in the general public.

Conclusions:
The IAC had a good overview of all aspects of the J-PARC operation thanks to well preparedpresentations. Excellent progress was made last year especially in responding to therecommendation made at the last review to focus on the delivery of science at the expense ofpushing the frontiers of the beam intensity. A conservative approach was followed to minimize
target failure risks and optimize beam delivery to users. This paid off for MLF users and MR
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users who produce novel results. This was also in line with recommendations made in the past on
risk management. Together with a significant improvement in establishing a safety culture at alllevels, the IAC finds that J-PARC is operating more and more along international norms.
Challenges remain in particular with the development of reliable high power targets and with
operation funding levels for the MR. Steps are being taken to strengthen the target groups and tointegrate the effort site wide. The upgrade of the MR power supplies has started ( 2 of the 3buildings needed are available) but is awaiting further funding to order the supplies and installthem. The time scale for this to happen is already shifted to JFY2022 and further delay willaffect the competitivity of the science program, notably the neutrino effort to nail down theparameters of CP violation in the neutrino sector and the Kaon program in the hadron hall.
Nevertheless, the IAC considers that the future of J-PARC is quite attractive and that a good casecan be made to obtain the resources needed to operate the facility reliably and at high power
level. However one should focus on the near future and urgent requirements (MR power supplies
and high power targets) before considering the longer term aspirations like second neutron target
and Hadron hall extensions. A J-PARC roadmap should present a strongly motivated near term
growth path which could be more palatable to the funding agencies together with an outline of aplausible longer term vision.
J-PARC has matured a lot and is already delivering exciting results. The J-PARC team is to becongratulated for achieving world class status in many aspects of the scientific program. The
IAC is pleased to extend its best wishes for the future.

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Appendix I
Agenda for the International Advisory Committee Meeting of J-PARC in 201821

Appendix II
IAC Committee members for 201822

Appendix III
Charges to IAC2018 from J-PARC by N. Saito, director•

Evaluate overall performance of J-PARC Center–

Promotion of science with safety••

Review safety activities at J-PARC–•

Each facility should have a good balance of user program andfacility improvements

Safety culture is well penetrated thru staff and users?

Any suggestions to improve the total performance are welcome. Our concerns
include but not limited to–

Budget situation–

Open access for users–

More uniform operation combining KEK, JAEA, and CROSS efforts is criticalto further success of MLF–

Governmental panel review is ongoing23