Neutron Advisory Committee Meeting for J-PARC MLF Facility
NAC2019
Tokai 18-19 February 2019
Committee members:
Robert McGreevy (chair), Bertrand Blau, Sung-Min Choi, Mark Wendel, Yoshiaki Kiyanagi,
Christiane Alba-Simionesco, Jamie Schulz, Yoshie Otake, Masaaki Sugiyama.
Charge to the committee:• Review our efforts to strengthen the facility- adequacy of renewed target development strategy in the context of 1MW stable
operation in a few years; including moderator cryogenics- timely construction and future direction of beam lines, sample environment anddevices to maintain the uniqueness of the facility• Evaluate the appropriateness of the science promotion efforts- activities of science group and science promotion board- any suggestions to help the smooth penetration of science driven atmosphere• Review our efforts to develop business model in MLF suitable to 1MW facility, especially thedirection in future• Any suggestions for improvements are appreciated. Our particular concerns include but are
not limited to the following:- yet to be unified MLF activities between JAEA, KEK, CROSS and Ibaraki prefecture,
as pointed out at the last NAC- improving paper production rate
- promotion of industrial use- user program handling and user support

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Target systems
The stable operation of target #8 at different power levels between 300kW and 500kW, and oftarget #9 mostly at 500kW, is recognized by the NAC. The overall availabilities of 90% and 93%
for targets #8 and #9, respectively, show that the chosen target improvement measures havebeen highly successful. To continue to improve understanding of the beam power dependency
on the pitting damage, the NAC recommends to maintain a simple power history. In thismanner, the post-irradiation examination (PIE) measurements can be reliably correlated tobeam power. Therefore, it is recommended to consider the move to higher power operation not
only from the user requirement point of view but also from the target design point.
The NAC would like to encourage the MLF operations team to establish a target management
plan for a long-term power ramp-up strategy taking into consideration the importance ofcorrelated PIE data to the target design. Starting in autumn 2019 the first constraint-free target,i.e. a target with a significant design change, will be installed for operation. MLF should consider
that such major changes might suggest a conservative approach to the beam power ramp-up,
perhaps either running the first constraint-free target at 500 kW or with a modest powerincrease.
The planned order of operation of the three constraint-free targets, coming from two different
suppliers and all being ready by end of March 2019, is not clear to the committee. This ordershould be discussed and agreed by stakeholders, including contingencies, and included in thetarget management plan.
The countermeasures against the performance degradation of the helium refrigeration systemtaken in 2016 appear very effective, as a new pressure drop increase after 15000 operating
hours was not observed. Nevertheless, a replacement of the ADS during the coming summer
shutdown as a precaution appears reasonable.
The yet unknown reduction of the helium gas flow rate to the bubbler is a crucial factor for
future beam power increase. Also, with the unconstrained version of the target, the vibration
measurement will not be so effective to monitor pressure pulse mitigation. It will then benecessary to rely on pressure measurements in the gas supply system to ensure that gas flow is
sufficiently high. A strategy to reliably monitor the gas injection rate should be decided anddesign changes proposed. If pressure measurements are used, the sensors should be capable ofmeasuring the full range of possible pressures.
Some vulnerabilities in the target may exist that are unknown at the current time. Therefore, aplan should be proposed to examine some of these areas through more extensive PIE, e.g.
including endoscopic investigation of the target interior surfaces all the way back to andincluding the bubblers after beam window cutting.
Although the tritium release during target replacement is well below the limits given by thesafety authorities it is strongly advised to investigate carefully the reason for its unexpected
increase during replacement of target #8. A good solution should be pursued to avoid sudden
release of large quantities of tritium when the target loops are disconnected. Different
techniques for either confining the residual tritium inside the target or slowly releasing it overan extended period of time could be envisaged. Even if this would lead to the unwanted side
effect of a prolonged target exchange time it should be considered as acceptable.

2Science promotion
Important efforts have been made over the last year to enhance the scientific activities and toestablish a stronger ‘science culture’ within MLF. MLF should continue to support and motivate
the science groups and to monitor how well they are working (e.g. common publications,meetings, students etc.).
The Science Promotion Board is playing an important role in promoting collaboration withexternal and industrial users, helping MLF staff to get resources through participation in grant
funded research and proposing the idea of public beam time on KEK and JAEA instruments. Thisshould be continued.
MLF should formally support the university branches as outstations and ensure semi-permanentcontact with the university members outside of experimental beamtime periods. Thesebranches can support the science groups and the development of activities such as deuteration,computing, sample environment development etc. Since this should lead to an increasing
number of students/postdocs based long term at J-PARC MLF need to improve the capabilities,e.g. accommodation, to host them.
The neutron scattering schools are well attended but the proportion of Japanese students
seems low. Efforts should be made to understand and rectify this.
Instrument development
The NAC congratulates MLF on the successful test of instrument performances at 1MW, thetransition of VIN-Rose to operation and the successful commissioning of POLANO. We arepleased to see that all instruments are operating well and are being maintained and upgraded(e.g. with additional detectors) in support of the user program.
The NAC endorses the neutron detector and polarising supermirror development activities. TheHe3 polarisation capability being installed on POLANO is a world first as an in-situ capability.
However, this activity is manpower intensive so installation on other instruments should be
carefully considered to ensure maximum return on investment.
Sample environment and laboratories
The SE team maintains common equipment such as cryogenics, magnets, high-temperature
furnaces, high pressure etc. The team mainly consists of beam line scientists so the total effort islimited. More dedicated technical support is needed in future if user expectations are to be met,
especially as experiment throughput increases with increasing power.
The deuteration laboratory and activity are slowly being built up. However, the manpower andequipment are limited. Often the deuteration effort required to produce the sample(s)considerably exceeds the effort required for the experiment itself. Dedicated staff andcollaboration with universities and other international deuteration facilities will therefore beneeded. Published results from samples produced and measured at MLFwill then be required toprovide the justification for this investment.
Industry3The industry program at MLF is significant in comparison to other international facilities.
However, the NAC suggests that MLF clarifies what the value of industry usage is to J-PARC (e.g.
promotional value to the government, income …) and determines the corresponding metrics ofsuccess other than just % of beamtime used. It is also important to evaluate activities on eachbeamline, not just overall.
Industry use is also part of the ‘business model’ (see below). Beamtime is limited, so more use
by one group necessarily means less use by another. Any decision on the level of industry use
needs to be strategic and informed by considerations of what is lost as well as what is gained.
But this balance may differ between countries and facilities.
The NAC understands that the industry programme on the SPICA instrument is highly successful
and recommends the inclusion of the high level industry statistics from it such as utilisation(days), number of experiments & number of companies as part of the industry
program. Otherwise this success is ‘hidden’.
The ambition to increase industry usage further is commendable. However, MLF must consider
how the necessary additional support can be provided. For example, the Ibaraki prefecture
model with an additional fee for industry usage might be followed, with this income going to
MLF to provide additional scientific or technical support for industry access.
User programme and publication rate
The NAC is pleased to see that the user satisfaction is increasing. It would also be good to seek
feedback from users on additional capability they would like to have at MLF (e.g. sample
environment, software, instruments).
The proposed data policy with a data embargo of 3 years is in line with other internationalfacilities. The proposed storage of raw and meta data for 10 years seems reasonable, but acost/benefit analysis could be performed to validate the retention period.
User access to data and computing infrastructure to perform data reduction and analysis
systems is critical for a world leading user facility. At present at MLF there are significant
inefficiencies for both users and facility staff in manually retrieving and transferring data.
International best practice to segregate facility operations from user operations could beachieved using an offsite data storage facility or creating a segregated network within J-PARC.
The NAC commends MLF on the number of user workshops being held. We suggest runningscience as well as instrument based workshops in order to cross-promote the capabilities ofmultiple beamlines.
The NAC recommends consistent and complete reporting of instrument demand and utilisation
to enable key observations to be made and trends to be identified, i.e. this should include all useof beamtime regardless of which programme uses it. The NAC suggests the following metrics
that could be reported:
Demand• Beamline demand - year by year on each beamline (last 5 years)• Country/Organisation demando average of the past 5 years
o last roundo current round4

Beamline Utilisation• Beamline usage (days) per use category as well as maintenance, instrument outages,commissioning & other relevant usages.
User Statistics• Number of individual users per year.
• Number of user visits per year
• Number of new users per year and demographics (country/organisation/position)
The usage of the mail-in program seems low, so we suggest that MLF promotes this access route
more strongly to users.
The NAC is pleased to see that the number of publications from MLF has increased in 2018. With
the actions being taken to improve publication rates, and the reliable operation since 2016, afurther increase in publications would be expected in 2019 and 2020. MLF should continue todetermine and reduce the bottlenecks from proposal to publication that limit scientific output.
The database of publications is very detailed and will provide a useful resource for tracking
outputs. The use of DoIs for MLF data, as is now being done by several facilities worldwide (seee.g. https://www.isis.stfc.ac.uk/Pages/Digital-Object-Identifiers-(DOIs)-for-ISIS-Data.aspx) might
be considered as another mechanism for tracking output.
Business model
The engagement of younger staff in discussing the business model is highly commended. TheNAC are very impressed by the high level approach; it is certainly not naïve. The choice of topics– management, safety, research results - is interesting. A lot of useful questions have beenraised by this exercise; the difficult challenge will now be how to address them. Some of theissues are generic/common to large organisations; JPARC and MLF are not unusual but do havea complex structure which can amplify issues.
‘We have no time to sharpen our axes’. This phrase neatly encapsulated the fact that staff
overload is a key issue. MLF staff are clearly dedicated and very hard working, but the current
situation is probably not sustainable.
Second target station
The approach is ambitious, as it should be, but to succeed scientifically, not just technically, will
require a good business model. All of the currently underfunded aspects of MLF need to be
included in any proposal, e.g. sample environment, computing, deuteration etc. The NAC
recommend that MLF look at the Oak Ridge ‘3 source strategy’ since the combination offacilities being considered – two target stations and a reactor - is the same. However, this is notan easy optimisation problem.
Conclusion•••

MLF has an excellent suite of instruments that provide the capability to produce
correspondingly excellent science.
It is clear that MLF staff are highly dedicated and working hard towards the success ofthe facility – but possibly they are working too hard.
Good progress is being made towards high power and reliable operation. This should becontinued. MLF should operate as much as possible during the 2020 main ring shutdown
to maintain the beamtime for users.
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The introduction of public beam time on KEK and JAEA beamlines, if it leads to more
uniformity of support across the beamlines, is strongly supported.
Industry use is strong but a clear understanding of the purpose and expected outcomes
would be helpful.
If increased synergy of neutrons and muons is a goal, then some merging of the advisorycommittees might be considered?
We look forward to the outcome of the business model development and further
progress towards the second target station.

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