REPORTOF THE
INTERNATIONAL ADVISORY COMMITTEE
ON THE J-PARC PROJECT

Meeting held February 27 – 28, 2017at the J-PARC Research Building, Tokai, Japan

April 3, 2017

Page 1TABLE OF CONTENTSEXECUTIVE SUMMARY ...........................................................

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MUON PHYSICS .......................................................................

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ACCELERATOR DRIVEN TRANSMUTATION ..............................

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MAJOR RECOMMENDATIONS

Accelerators
SafetyMaterials and Life Sciences Facilities
Nuclear and Particle Physics

Accelerator Driven Transmutation
INTRODUCTION
SAFETYACCELERATORS

MATERIALS AND LIFE SCIENCES – NEUTRONSMATERIALS AND LIFE SCIENCES – MUONSNUCLEAR AND PARTICLE PHYSICS – GENERAL COMMENTS
NEUTRINOS

NUCLEAR PHYSICS
KAON PHYSICSAPPENDIX I – MEETING AGENDA
APPENDIX II – IAC MEMBERS

APPENDIX III – CHARGE TO IAC

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Executive Summary
The International Advisory Committee (IAC) of J-PARC met at the laboratory on February 27
and 28, 2017 to evaluate the performance of J-PARC over the past year and to provide
recommendations on proposed future directions for the J-PARC programs. The IAC commends
the laboratory on the improvements that have been made to accelerator system, which led to very
good reliability for beams into the MLF. Some issues still remain for providing beam with highefficiency for the neutrino experiment. Major advances were made in all experimental areas
during the past year. In the Materials and Life Science (MLF) area, the IAC notes that J-PARC
has done an excellent job in attracting industrial users to the facility. The high efficiency forbeam on the neutron target has led to many experiments being completed there. Advances havealso been made in developing an ultra-slow muon beam. In the Nuclear and Particle Physics
program, the T2K collaboration has submitted a paper for publication that gives the first hints of
CP violation occurring in the neutrino sector. Advances have been made in experiments using
muons and kaons to test the Standard Model of particle and nuclear physics at high precision.
The ADS effort developed a Technical Design Report that was reviewed by an external
committee late in 2016. A few modifications were suggested that are now being implemented.
Proceeding to the construction phase requires a decision be made by the Japanese government on
how the project fits within the newly revised energy policy of Japan. Strong support from theorganizations that fund J-PARC—MEXT through KEK and JAEA—was shown at the IAC
meeting. But the funding level supporting operations for the Nuclear and Particle Physics
program is severely limiting the number of hours that the facility can provide a neutrino beamand deliver beam to the Hadron Experimental Facility. The delay in obtaining funds to replace
the power supplies on the Main Ring accelerator will further limit the number of protons on
target that can be delivered to the T2K collaboration. These issues threaten the world-leadership
position that Japan has enjoyed in neutrino physics. Finally, the IAC applauds the efforts JPARC has made in elevating the message that safe operations are a high priority at the laboratory
and encourages the laboratory to sustain these efforts into the future.

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Major Recommendations
GeneralThe IAC strongly encourages J-PARC to adopt the open campus concept. This will provide
much better access for users at the facilities, thus making J-PARC more attractive to bothresearchers and local communities.
Accelerators
Pursue a higher reliability for the accelerator complex with a goal of at least 90% availability
for the MR operation.
Procure, construct, install and commission the new MR power supplies and start operation at thefaster repetition rate as soon as possible.
SafetyMaintain the momentum gained this past year in advancing safe operations at J-PARC anddetermine if a local ‘Stop Work’ order can be implemented to stop an action that could lead toimminent danger if continued.
Materials and Life Sciences Facilities
Neutrons: The IAC recommends a more cautious approach to power ramp up in the MLF.
Reliability should continue to be given preference over increasing power, until the upgradedtarget #10 becomes available after summer 2018. We understand that Target #2 might be at risk
from cavitation damage if operated beyond summer 2017 so Target #8 and its backup, theidentical Target #9 (which only becomes available in early 2018), must be operated with somecaution so as not to put the MLF program at reputational risk. Failure is not an option.
Neutrons: Develop a coherent strategic science plan which sets out the scientific agenda of MLF
and defines a set of prioritized instrument and technique developments.
Muons: Seek out specialized expertise to help solve the limitations of the laser amplifier rod toimprove the intensity of the ultra-slow muon source, possibly through hiring an external expert
for a sabbatical period.
Nuclear and Particle Physics
General: Seek increased operating funding for main ring operations.
General: Explore the possibility of increasing the flexibility of MR operation to make more
efficient use of the facility and serve more users.
Neutrinos: Procure, construct, install and commission the new MR power supplies and start
operation at the faster repetition rate as soon as possible.
Nuclear Physics: Continue the experimental studies of the various aspects of strangeness innuclei, and develop a plan for an exciting hadron physics program exploiting the envisioned
upgrade of the Hadron Experimental Facility intensities.

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Kaons: Proceed with the calorimeter upgrade and demonstrate improved performance. A
further step will be made with the SX upgrade as a result of the new power supplies in the mainring.
Muons: Both the COMET and g-2 experiments are high priority for J-PARC. COMET, inparticular, has the possibility of being ahead of the competition and should endeavor to move
forward as quickly as possible.
Accelerator Driven Transmutation
Make a concerted effort to get approval from the government for the construction of TEF within
J-PARC, by concentrating on the TEF-T that is of value in the international scene of Accelerator
Driven Systems and material testing. Conduct careful safety studies of TEF-P.
Continue the support R&D needed to secure the TEF construction (for prioritization consider as
first priority the realization of TEF-T and refer to the T-TAC report of the December, 2016,
Meeting).
Start R&D activities on accelerator reliability improvements to meet the very demanding
requirement of ADS application and that will be beneficial to all J-PARC applications.

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Introduction
The J-PARC IAC met at the laboratory on February 27-28, 2017. Four members of the IAC
were unable to attend the meeting (J.-M. Poutissou, H. Fukuyama, P. Langan, and P. McBride).
Following an overview by Director Saito, the committee heard presentations on the safety
program, accelerator operations and from the different science programs underway at J-PARC.
Representatives of JAEA, KEK, and MEXT were able to join the meeting during the afternoon
of February 27 and provided the committee with their views on the J-PARC programs. The
committee met with laboratory staff and officials, including the mayor of Tokaimura, at a
reception on the evening of February 27. It was great to hear the comments made by the mayorthat indicate a trusting relationship between the laboratory and the surrounding community. This
is often difficult to develop and is easy to lose.
J-PARC has a very broad science agenda ranging from fundamental studies that search for
deviations from the Standard Model of particle and nuclear physics to studies for material andlife sciences that include many applications for industry. During 2016, advances were made on
all of these fronts, as will be noted below in the detailed reports on the science programs.
Accelerator operations are at the center of this as all the science programs require proton beams
on target to advance. Efforts made in the past several years to improve the reliability of theaccelerator systems are now being realized. During 2016, over 2600 hours of beam were
supplied to the Materials and Life Science Facility (MLF). The decision was made to operate at
150 kW of beam power in the MLF in order to ensure that the neutron target now in place would
not be damaged. The IAC applauds this decision noting that the MLF operated at highefficiency, having over 90% of the available time with beam on target. This high efficiency isvery important for a facility with a large number of users. Over 2000 hours of beam werescheduled for the neutrino program but issues primarily in the accelerator lead to just over 1500
hours of usable beam at a maximum beam power of 470 kW. The program of science in the
Hadron Hall had over 616 hours scheduled and utilized 515 of them. The beam power available
there was typically 42 kW. In all areas, the amount of beam time on target was limited bybudget constraints.
Nearly all of the programs at J-PARC require secondary beams. Thus beam power is an
important consideration. The MLF beam power is limited today by the neutron target and not
the accelerator. Much work has been done to design and construct a new target that should allow
significantly higher beam powers to be delivered. The decisions for when to install the newtarget and how quickly to ramp up the beam power to it need to be carefully considered. There is
no doubt that the new target is being engineered to withstand high power but failure modes
usually occur because of some lack of understanding of how materials work under high radiation
environments. Thus the IAC recommends that a backup target be available before significant
increases in beam power are applied to a new target. For the MLF users, stable beam at lower
power is likely preferable to long periods of no beam due to target failure. The beam power tothe neutrino and Hadron Hall experiments can be improved by shortening the Main Ring (MR)accelerator cycle time with the new MR power supplies. New power supplies, which have been
designed and are ready to be built, will cut the cycle time in half. This will allow the beam
power at the neutrino target to be increased to over 700 kW immediately and to close to 1 MW
within a couple of years of operation. The new supplies will also provide significant
improvements in both beam power and beam quality for experiments in the Hadron

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Experimental Facility. The IAC strongly urges engaging with partners and funding agencies towork together to provide the resources for this critical upgrade.
A Technical Design Report has been developed for a 2018 start to the construction of the
Accelerator Driven System Test Facility for Nuclear Transmutation. The report was recently
reviewed and found to be very close to final—a few modifications were suggested that are now
being implemented. With this report in hand, J-PARC is ready to advance toward theconstruction of the test facility. Recent decisions within the Japanese government have led topossible delays in proceeding with this program. It is important for the laboratory to seek
clarification soon as to the program’s status in order to not lose critical personnel if the programis to continue.
Over the past year, J-PARC management has continued its efforts to implement a safety programthat reaches out to all laboratory employees. A major attribute of the program is that all
employees should be watching out for the safety of themselves and their colleagues as they carryout their work. This effort has been named ‘Mindful of Others’ as it has been rolled out to thestaff. It appears to the IAC that this effort has been quite successful in raising the awareness of
the importance to maintain a safe operating environment at the lab. We applaud this innovative
approach and urge that the momentum gained this past year be used to propel the lab forward in
the future as it strives for an excellent safety record.
In the opening remarks by the Director, a proposed ‘open campus’ vision was given that wouldchange the entrance of the laboratory to a location that would not require the heightened level of
security that is now in place. The new entrance would allow the sensitive areas under JAEA to
be completely separated from J-PARC. With the large number of users that are now working at
the lab and the expectation that many more users will be coming in the future as the facilities
further mature, this change to an open campus is highly desirable.
Recommendation: The IAC strongly encourages J-PARC to adopt the open campus concept.
This will provide much better access for users at the facilities, thus making J-PARC more
attractive to both researchers and local communities.
Below we summarize the reports on the different areas that make up the accelerator operations
and the science programs at J-PARC.

SafetyThe report to the IAC on safety at the laboratory reviewed the efforts that were made during thepast year to implement the recommendations made by the IAC in its 2016 report. Much work
has been done with positive results. The lab has been engaging the staff in an effort to makesafety a high priority. The approach has been to engage staff to be aware of their own safety andthose of workers in their area through an approach that was called ‘Mindful of Others.’ From
what the IAC heard, this appears to be successful. The experience with safety programs at otherlabs shows that it is important to maintain continuing engagement with the staff for long termchanges in the safety culture.

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During the past year, a drill simulating an accident was carried out that demonstrated a number
of issues. The lab is to be congratulated on carrying out this drill. From the lessons learned, it isimportant to implement changes in how the lab responds to an emergency and test that thechanges have been effective by carrying out another drill in the near future.
Most of the members of the IAC work at laboratories outside of Japan. It is typical for
employees to have the ability to issue a ‘stop work’ order when imminent danger is seen inallowing work to progress. If this is done, a formal process is put into motion to evaluate thework underway and make changes where appropriate. Last year the IAC recommended that JPARC develop a similar procedure. In the presentation on safety at the lab, it was noted that theability to ‘stop work’ is not something that is recognized in Japan. The IAC recommends thatthe laboratory institute a policy for J-PARC that replicates a ‘stop work’ action in order toprovide a way to mitigate a major accident from occurring when it could be avoided.
Recommendation: Maintain the momentum gained this past year in advancing safe operations at
J-PARC and determine if a local ‘Stop Work’ order can be implemented to stop an action that
could lead to imminent danger if continued.

Accelerators
The J-PARC facility has operated very well during the last year with a strong emphasis on theusers program. The changes made in the accelerator systems to improve stability led to steady
operation of MLF with an availability of 93%. This resulted in a very significant number ofscience results being produced.
The MR has achieved the new record beam power of 470 kW for fast extracted beam and 42 kW
for slow extracted beam. Several equipment failures are still impacting reliable operation of theMR, the beam transport to the targets and the targets themselves. The reliability improvement
efforts of the J-PARC facility should be strengthened to achieve the high level of availability thatis expected from all parts of this world-class user facility.
The quality of the RCS space charge simulations and the degree to which they agree withmeasurements is very impressive. Reducing beam loss to 0.2% for a 1 MW equivalent beam
power is a very significant achievement. It should lead to very good operation into the MLF
when a new target is in place that can survive with a sustained high power beam.
To reach the phase 1 design goal of 750 kW from the MR and to keep the T2K neutrino
experiment internationally competitive it is critical that the new MR power supplies areconstructed and installed in a timely way.
Recommendations:Pursue a higher reliability for the accelerator complex with a goal of at least 90% availability
for the MR operation.
Procure, construct, install and commission the new MR power supplies and start operation at thefaster repetition rate as soon as possible.

Page 8Materials and Life Sciences -Neutrons
Significant progress has been made on many fronts since the last IAC review. Users havewelcomed the >90% reliability that has been achieved at 200kW. Indeed, the 25 Hz MLF
neutron target with its highly optimized cold moderators is an impressive source on the world
scale. MW capability has been demonstrated by the RCS accelerator, but a cautious approach tothe future ramping up of beam power is recommended.
J-PARC is on a path to becoming a major center for neutron scattering research but recent
structural problems with the mercury target, seen while operating at power levels of ~500 kW,
will delay achieving that goal. The approach of operating at reduced power levels of ~200 kW inorder to preserve reliability until a solution is fully developed is very sensible. Operating at highreliability and reduced power levels will allow for continued growth in the science program. The
next generation target designs may solve the problem but are as yet untested and it is not clear towhat extent cavitation will be a problem at higher power levels
Recommendation
The IAC recommends a more cautious approach to power ramp up in the MLF. Reliability
should continue to be given preference over increasing power, until the upgraded target #10
becomes available after summer 2018. We understand that Target #2 might be at risk fromcavitation damage if operated beyond summer 2017 so Target #8 and its backup, the identical
Target #9 (which only becomes available in early 2018), must be operated with some caution so
as not to put the MLF program at reputational risk. Failure is not an option.
The rate of construction of new neutron scattering instruments at MLF over the past few years
has been impressive. MLF now has a portfolio of world-class instruments with 21 out of 23
beam ports being instrumented. Even with 150 kW of beam power, the 25 Hz rate with highly
optimized moderators and over 90% reliability makes it a potent source. Furthermore, thesignificant engagement by industrial users is unprecedented and ‘headline’ papers are now
appearing in prestige journals. J-PARC can be proud of these achievements. However, thescientific productivity from these instruments, as measured by the number of publications, hasbeen limited likely due in part to past issues with source reliability. Nonetheless, it may be
helpful to conduct a careful analysis of each instrument in order to identify any bottlenecks in the
publication pipeline. This should include all aspects of the scientific performance including datacollection, reduction, and analysis software, sample environment, instrument hardware, ancillarylaboratories, staffing levels, etc., and be compared to user expectations and requirements. Any
gaps between present performance and expected performance should be identified and aprioritized plan should be developed to address these gaps in a systematic way. In addition, thisanalysis should include a bench marking exercise in which the scientific productivity (# ofpapers) of each instrument is compared to similar instruments at other sources. This would help
in identifying where the greatest improvements in scientific productivity might be realized,
assisting MLF management in setting priorities.
Beyond any limitations in instrument performance, it is important to provide an environment for
beam line staff that promotes a strong science and innovation culture. Aligning staff in crosscutting scientific groups and developing a uniform approach to all users may help. Setting staff

Page 9very clear expectations for scientific productivity and then rewarding those who achieve those
expectations may also help. As MLF continues the difficult transition from a construction
project to a mature facility, it may also be important to ensure that early career staff have strong
scientific mentorship and that they are encouraged to fully engage in mainstream scientificcommunities through participating in conferences and in professional societies.
Recommendation
Develop a coherent strategic science plan which sets out the scientific agenda of MLF anddefines a set of prioritized instrument and technique developments.

Materials and Life Sciences – Muons
Encouraging progress has been made on all four beamlines and their associated instruments. A
significant landmark was provided by the generation of the first ultra-slow muons in February,
2016. A steady increase in the rate has been obtained by tuning and optimizing the beamline,
however the absolute counting rate is still 1 to 2 orders of magnitude below that needed for a
viable user facility offering USM SR. The current limiting factor is the quality of Nd:YGAG
material forming the laser amplifier rod. Alternatives to this material have been explored;
however this has not yet led to a viable fallback solution.
Recommendation
Seek out specialized expertise to help solve the limitations of the laser amplifier rod to improve
the intensity of the ultra-slow muon source, possibly through hiring an external expert for asabbatical period.
Progress has also now been made on the H-line with front end devices, beam line elements andthe iron shielding in place, including that for the H1 area to house the DeeMe/MuSEUM
experiments. We particularly applaud the creation of a new position for a physicist dedicated to
the H-line. This will be important to efficiently complete the H-line and to efficiently organize
the logistics and infrastructure. Still a point of concern for H-line is the available electrical
power in the area. The laboratory management is encouraged to arrange for a schedule toupgrade the power in the area that enables the beam line to be operated. This will enable atimely start of the physics program for the envisaged fundamental physics experiments.
The first part of the new S-line surface muon channel (S1) has now been commissioned. This isofficially open from April 2017 and will reduce the previous heavy load on the D-line. The Dline will then become a special line dedicated to high-momentum muons and negative muon
experiments. After the replacement of the superconducting solenoid of the D-line with a warm
bore window-free design, the momentum range of the negative muons has been expanded tocover 65 keV to 54 MeV. This will open up new applications based on muonic-X-ray elemental
analysis as a function of depth and tomographic imaging has also been demonstrated using
pixelated detectors.
A clearly demonstrated fully functioning USM beamline will be the strongest internationallyunique feature of MUSE and should remain the highest priority. Completion of the H-line intimely manner to start to deliver the fundamental physics program in the H1 area should be thenext priority. Beyond the completion of H1, a roadmap should be drawn up for further

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developments. S1 now provides the first dedicated surface muon SR instrument at MUSE,
which should have the most widespread initial appeal to the SR community. This presents agood opportunity to support and expand the user base and boost the scientific output of the
facility.

Nuclear and Particle Physics – General Comments
The nuclear and particle physics program includes the neutrino program with the fast extracted
beam from the main ring, the kaon decay, hadron physics and hypernuclear physics programs in
the hadron hall with slow extracted beam from the main ring, and muon physics, both in the
hadron hall with the COMET experiment and in the muon beams of the MLF facility. There has
been significant progress in increasing the beam intensities in each area and beam powers thatare approximately half of the near-term goals have now been achieved for the neutrino program(470 kW) and in the slow extracted beam (42 kW). The improvement of the average duty factor
for the slow extracted beam from ~40% to 55% was a notable achievement. Plans are in place toincrease the beam power in each mode to and perhaps above the near-term goals. Potential
concerns are the lower beam availability this year of the fast extracted beam (69%) and the lackof backup production targets for the slow extracted beam. The R&D for the 100 kW slow spillproduction target based on a quite different design is also very important. The consolidation of
the vacuum system for the hadron primary beam line has just been completed.
Major progress has been made on the construction of the beam line for the COMET experimentand commissioning will begin this year. The planned hadron hall extension would increase themultiplicity of simultaneous running slow-extraction experiments and provide more optimized
beam in different energy ranges. The complexity of achieving sufficient beam time for the fastand slow extracted beam programs will increase as a third mode, dedicated 8 GeV proton
running for the COMET beam, comes into operation.
The IAC has two general recommendations for the Nuclear and Particle Physics program.
Recommendations:Seek increased operating funding for main ring operations.
Explore the possibility of increasing the flexibility of MR operation to make more efficient use of
the facility and serve more users.

Neutrinos
The J-PARC long base line neutrino program using the Super-K detector at Kamioka is one of
the leaders in the world-wide effort to discover if the CP symmetry is violated in neutrino
mixing. This observation would provide important insight on the potential role of the neutrino
sector in the preponderance of matter over antimatter in the universe. The recent T2K
collaboration result that the CP conservation hypothesis is disfavored at the 90% confidence
level is especially notable. The importance of the result is emphasized by the intensecompetition from the NOVA experiment at FNAL, which is the highest priority effort at that
U.S. laboratory. NOVA is releasing preliminary results with comparable discriminating power.
The science goals are of sufficient importance that these intense competing efforts are well
warranted. Indeed combining the data from the two experiments can increase the discrimination
power over that of a single experiment. Secondly the two different experiments have different
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11systematic errors for the identification of electron neutrino events, where potential backgrounds
may be lurking. Experience shows that either program could be unfortunate enough to suffer amajor setback that could delay future results and leave the path open for the other.
It is remarkable that the event rates of the two experiments are quite comparable. FNAL runs for~9 months a year with a 120 GeV ~700 kW proton beam. If J-PARC runs 4-5 months a yearwith 30 GeV ~470 kW beam, the event rate per proton on target and event rate per year are quite
similar. For J-PARC, it should be a high priority to maintain the operating schedule andefficiency that preserves this parity. The committee heard that the limitations of the operating
budget for physics at the main ring make this a real challenge for the near future. This must be asustained program. It is essential that the program be optimized recognizing that time scale.
The replacement of the main ring power supplies to enable the delivery of 750 kW of beam
power, now expected to occur in 2019, is the centerpiece of the improvements planned for JPARC. Credible options to further increase the beam power to 1.3 MW have been identified. In
the long term, all of these contribute to world-leading scientific power of the proposed Hyper-K
detector that is the primary vision for the future of the Japan’s neutrino physics program.
Decisions on other trade-offs between near-term running, improved reliability, and future
improvements are delicate ones and the path to optimization would appear quite soft. Either
extreme is likely to be a mistake, over commitment to production data taking could jeopardize
other important J-PARC physics communities and the long-term maintainability of the neutrino
beam. On the other hand, a temporary halt in production data taking could undercut the moraleof the collaboration, where important attempts to improve the reconstruction efficiency and event
characterization are underway, and damage the international perspective of the laboratories
commitment to this science. We strongly support the Laboratory’s efforts to obtain additional
operating funds for the exciting main ring experimental program.
Recommendation: Procure, construct, install and commission the new MR power supplies andstart operation at the faster repetition rate as soon as possible.

Nuclear Physics
The nuclear physics activities concentrate on experimental studies of strangeness in nuclei,
motivated by quests to unify the forces among the members of the baryon octet and to constrain
the KN, N and  interactions in the nuclear medium. It is now beginning to focus on
multiply strange systems. As highlights in a pilot experiment performed in recent years, the JPARC group found some excess in the 12Be missing mass spectrum, which is tentatively related
to a potential bound state. A new effort has begun to observe hypernuclear states in emulsion
experiments exploiting a novel scanning method. An upcoming run later this year is expected todeliver a multitude more double hypernuclear states for nuclei lighter than oxygen, which will
likely improve the knowledge of the - interaction. Future experiments will search for the Hdibaryon, which recent lattice QCD calculations predict as a resonant state near the -threshold, and for a potential bound state in the K-pp system, indicated in a recent JPARC
experiment. Another planned experiment will search for medium modifications for vector
mesons in the nuclear medium.

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In the midterm future, after an extension of the Hadron Experimental Facility, spectroscopy of
medium and heavy  hypernuclei as well as production and studies of neutron-rich hypernuclei
are envisioned. These investigations aim at constraining the -N interaction in the medium with
relevance for neutron star models.
The nuclear physics program is scientifically very sound and of significant relevance to nuclear
astrophysics. It also produces a quite impressive number of PhD and master theses and hence
successfully serves to educate the next-generation scientists.
Recommendation: Continue the experimental studies of the various aspects of strangeness innuclei, while, and develop a plan for an exciting hadron physics program exploiting theenvisioned upgrade of the Hadron Experimental Facility intensities.

Kaon Physics
The Kaon program addresses physics beyond the standard model by testing lepton flavor
universality (E36) and looking for CP violating ultra-rare decays of KL (KOTO).
Experiment E36 has completed data taking in 2015 using the beam from the main ring and is
now analyzing the electron/muon ratio of K+ decays. The helicity suppression in electron decaysa priori yields a high sensitivity for new physics. E36 hope to improve the current world averageon this by a factor 2 in accuracy. They see clear signals of the K+ decays for both muons andelectrons. The analysis is ongoing, with continued improvements being made for particle
identification and tracking, and an update on the attainable accuracy will be presented in 2017.
Meanwhile the experiment has been dismantled.
The KOTO Experiment is installed in the Hadron hall (as E14) and tries to observe the rare
decay of KL0bar using the slow-extracted beam of the main ring. The signal, 2-gamma
decay of the pion, and nothing else, requires low backgrounds and the goal for the branchingration limit to be measured requires the maximum number of KL. The collaboration has installeda new barrel detector and used the KL decays to 4 or 6 gammas (from 2 or 3 0, respectively) tounderstand backgrounds. Halo neutrons and the three  decay of the KL with escaping charged
's constitute the main backgrounds. The position along the decay volume is used to define a yetblinded signal region. A priori, 1 event corresponds to 10-9 sensitivity ignoring background.
They are examining a CsI calorimeter with MPPC or PMT readout upstream and downstream
respectively as a veto which should increase sensitivity by an order of magnitude in 2018. A
DAQ upgrade is planned for 2017. They require the power supply upgrade of the main ring to
reduce the ripple so that the spill duty factor can be doubled (45% to 100%) and the main ringslow extraction cycle time can reduced from every 5.5s to every 4s. At CERN, NA62 is trying to
improve the accuracy on the equivalent charged K decay to 10%. The experiments arecomplementary as deviations from the SM would require different explanations as to the type of
new physics. The IAC notes good progress on this effort and supports work to proceed with thecalorimeter upgrade and demonstrate improved performance. A further step will be made withthe slow extraction upgrade as a result of the new power supplies in the main ring.

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Recommendation
Proceed with the calorimeter upgrade and demonstrate improved performance. A further step
will be made with the SX upgrade as a result of the new power supplies in the main ring.

Muon Physics
J-PARC has an ambitious and exciting program of fundamental physics with muons planned forthe near future. Two large projects, a new measurement of the muon g-2 factor and a -econversion experiment, COMET, are competing with experiments at Fermilab with similar goals.
COMET is being staged in the Hadron Hall and will use an 8 GeV - beam. The g-2
measurement will be done in the MLF area using an accelerated beam of ultra-cold muons to
produce a 300 MeV/c muon beam with very small emittance. Two smaller experiments, DeeMeand MuSEUM are also being planned for muon beams in the MLF hall.
The COMET experiment is being carried out in two phases. It now has stage-2 approval for the
first phase and beam line and detector construction are underway. In the first phase, a shorterbeam line will be used following the production target where a primary beam of 3.4 kW using
slow extraction will produce the secondary muons. The goal of the first phase is a measurement
sensitivity of ~10-15 for the conversion. Commissioning of the beam line and detector
components will begin in 2019 at the earliest. In 2017, tests of 8 GeV acceleration and bunchedslow extraction, as well as a measurement of the proton beam extinction, will be performed. The
second phase of COMET requires a substantially longer beam line to reduce backgrounds. The
plans for the next phase call for 56 kW of primary proton beam power, again using slow
extraction, in order to reach an overall sensitivity of ~10-17. The IAC strongly supports the work
heading toward the first measurements with COMET. The effort appears to be on track to be thefirst new generation -e conversion experiment to run.
The g-2 experiment at J-PARC uses a very different approach than the most recent experimentthat was carried out at Brookhaven National Lab. The storage ring that was used at BNL has
been moved to Fermilab where a muon production beam line is being built to supply muons to
the ring for a new, higher statistics, measurement. The g-2 experiment being developed at JPARC will have very different systematic effects than the BNL and Fermilab measurements.
As noted above, the J-PARC approach to g-2 requires accelerating an ultra-cold muon beam
produced from laser-ablated aerogel. The initial goal of producing such a beam has beenachieved and further improvements are underway on the D-line in the MLF. Work on the beam
production has been on-going over the past year with good success. A further test has been
approved at the D2 area for March, 2017. The g-2 collaboration put together a TDR plan forstaging the experiment that was reviewed in November, 2016, by the PAC. The outcome of the
PAC review was to develop a fast track plan to carry out the first phase of the experiment in atimely and cost-effective manner. Following the resolution of some remaining issues, the PAC
noted that the experiment should be ready for Stage-2 approval. The collaboration is now
working on these remaining issues. The IAC is very supportive of this effort. It will be
extremely important to carry out a sensitive measurement with this very different approach.

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The DeeMe experiment will search for -e conversion in the production target at MUSE H-line.
The group working on DeeMe has completed and tested the tracking detectors that precede thespectrometer magnet, which also has been completed. The experiment is now waiting on theconstruction of the H-line at MUSE. The anticipated sensitivity at DeeMe is ~10-13 with agraphite target and ~5x10-15 with a SiC target. MuSEUM is an experiment to measure the hyperfine splitting in muonium. It has now completed two runs and has successfully measured a
hyper-fine resonance curve. Work is continuing on MuSEUM to improve its sensitivity.
Recommendation
Both the COMET and g-2 experiments are high priority for J-PARC. COMET, in particular, has
the possibility of being ahead of the competition and should endeavor to move forward as
quickly as possible on the phase-1 version.

Accelerator Driven Transmutation Research
In the report to the IAC on Accelerator Driven Systems, the head of the Nuclear Transmutation
Division of J-PARC, reviewed the strategy proposed by JAEA to reach the deployment ofindustrial based ADS for the purpose of handling high level nuclear waste via transmutation. He
described the progress accomplished on the Transmutation Experimental Facility (TEF) design
and the associated R&D support program. He also presented the assessment work andrecommendations of the T-TAC (Transmutation – Technical Advisory Committee) that held its
annual meeting on December 12-14, 2016, as well as the actions taken corresponding to the
IAC’2016 recommendations.
The IAC acknowledges the prompt actions J-PARC has taken in response to the 2016
recommendations and commends management for having requested the production of theTechnical Design Report for TEF-T and consolidated the collaborations with the internationalgroups in the field of ADS development.
The IAC acknowledges the enhanced importance of ADS activity within J-PARC through thecreation of two sections under the Nuclear Transmutation Division, one in charge of the support
R&D program and the other dedicated to the design of the TEF facility and the preparation of its
use later.
The IAC acknowledges the very detailed recommendations of T-TAC for the TEF related to theimprovement of the TDR of the TEF and the support program on Heavy Liquid Metal
technology, dedicated instrumentation (Oxygen-meters and HLM US-flowmeters) and therecommendation for safety assessment on TEF-P. Building on this evaluation report and thegeneral view and prospect of the evolution of J-PARC in terms of accessibility as an open-user
facility sketched by the director of J-PARC Dr Saito and on the importance of the ADS activities
at J-PARC for JAEA as stressed by the Executive Director of JAEA Dr Yukitoshi Miura, theIAC proposes the following recommendations.
Recommendations:
Make a concerted effort to get approval from the government for the construction of TEF within
J-PARC, by concentrating on the TEF-T that is of value in the international scene of Accelerator
Driven Systems and material testing. Conduct careful safety studies of TEF-P.

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Continue the support R&D needed to secure the TEF construction (for prioritization consider as
first priority the realization of TEF-T and refer to the T-TAC report of the December, 2016,
Meeting).
Start R&D activities on accelerator reliability improvements to meet the very demanding
requirement of ADS application and that will be beneficial to all J-PARC applications.

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APPENDIX II
Jean-Michel Poutissou

TRIUMF

Francis Pratt

STFC(ISIS Neutron and Muon Source)

Jun Sugiyama

Toyota Central R&D Labs. Inc

Thomas Roser

Brookhaven National Laboratory

Shinian Fu

Institute of High Energy Physics

Eckhard Elsen

European Organization for Nuclear
Research(CERN)

Patricia McBride

Fermi National Accelerator Laboratory

Robert Tribble

Brookhaven National Laboratory

Donald F. Geesaman

Argonne National Laboratory

Karlheinz Langanke
Hirotada Ohashi

GSI Helmholtzzentrum für
Schwerionenforschung GmbH
Department of Systems Innovation, Schoolof Engineering, University of Tokyo

Hamid Aït Abderrahim

SCK•CEN

Paul Langan

Oak Ridge National Laboratory

Hidetoshi Fukuyama
Dan Alan Neumann
Andrew Dawson Taylor

Research Institute for Science &Technology, Tokyo University of Science
National Institute of Standards andTechnology
National Laboratories, Science andTechnology Facilities Council

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APENDIX III

Charge to IAC 2017
• Evaluate overall performance of J‐PARC
Center– Promotion of science with safety• Each facility should have a good balance ofuser program and facility improvements• Review safety activities at J‐PARC– 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 critical to further
success of MLF– Governmental panel review is approaching
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