Neutron Advisory Committee Meeting for J-PARC MLF Facility
NAC2018
Tokai 26-27 February 2018
Committee members:
Robert McGreevy (chair), Dimitri Argyriou, Bertrand Blau, Mark Wendel, Yoshiaki Kiyanagi,
Chang Hee Lee, Christiane Alba-Simionesco, Jamie Schulz and Mitsuhiro Shibayama .
The committee thanks the participants for the detailed presentations and their helpful and open
responses to the discussions. The committee highly values the hospitality and excellent support
provided during the committee meeting.
Charge to the committee:
1. Review our efforts to strengthen the facility
a. Adequacy of renewed target development strategy in the context of 1 MW stable operation
in a few years; including moderator cryogenics
b. Timely construction and future direction of beam lines, sample environment and devices tomaintain the uniqueness of the facility
2. Evaluate the appropriateness of the science promotion effortsa. Activities of science group and science promotion board
b. Any suggestions to help the smooth penetration of science driven atmosphere
3. Any suggestions for improvements are appreciated. Our particular concerns include but notlimited to the following:a. Yet to be unified MLF activities between JAEA, KEK, CROSS, and Ibaraki prefecture,pointed out at the last NAC
b. Improving paper production ratec. Promotion of industrial use
d. Direction of life science in MLF
e. User program handling and user support

1as1. Review our efforts to strengthen the facility
a. Adequacy of renewed target development strategy in the context of 1 MW stable operation
in a few years; including moderator cryogenics
TargetMLF has successfully stabilized target operations at mid-range power levels (300-400 kW) leading tohigh reliability of the facility during operation in 2017 and enabling a productive science programme.
This has established a solid basis from which further power increases can proceed.
For the first time, with target #8, it should be possible to measure the mitigating effect of gas
injection on the cavitation damage. However, target #8 cavitation damage results will be harder tointerpret because the target was operated at three different power levels for prolonged periods,
though results could still provide a point of reference for future targets operated at higher powers.
SNS cavitation data and gas injection experience is also beginning to become available. MLF shouldcollaborate with SNS on predictive models for cavitation damage.
Design and analysis efforts have successfully led to target designs with partially and totally
decoupled water shrouds which should enable future power increases up to 1 MW. However, asteady and systematic approach to power increases on the target should continue.
A careful incremental increase in beam power is more important than reaching 1 MW quickly. Large
increases in power, beyond the limits of confidence based on prior operational experience, create a
disproportionately high risk for target failure. MLF should also consider running targets at a single
power level (apart from very short accelerator tests) to maximize performance data that are usefulfor estimating target lifetimes at higher powers.
Target #10, which is a new design as the first partial-constraint-free target, might not be deliveredon schedule in Fall 2018. A strategy for neutron production should therefore be developed that
accounts for this contingency, e.g. whether or not target #9 would be used.
Storage of spent targets will be limited to about 10 years for the new RAM building, so longer termplanning for additional capacity will be required soon.
Cryogenics
All counter-measures against the former performance degradation of the helium refrigeration
system appear effective. In particular, the intensive cleaning of the affected heat exchangers, incombination with the improvement of the ADS, was obviously successful. Additional differential
pressure gauges and the introduction of a cold trap as a monitoring system for the oil concentrationin the helium appear to provide an effective early warning system.
Because HX1 and HX2 efficiencies will decline again due to accumulation of the normal oilconcentration, it is recommended that a spare clean set of heat exchangers be kept in stock. They
could be installed while the other set is being cleaned.

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b. Timely construction and future direction of beam lines, sample environment and devices tomaintain the uniqueness of the facility
Instrument development
Overall the NAC is impressed with the construction and technical development activities withrespect to both instruments and development and construction of targets. These highly appreciatedskills lay a solid foundation for the continual renewal of the facility.
The NAC is pleased to see a number of upgrades delivered on the beamlines over the past year. The
proposed future beamline upgrades and developments presented appear to be well thought
through. However, these activities should be aligned and prioritised according to the needs of theuser community and the resources available to deliver and operate them and should be planned tominimise interruption to the user program.
SE and laboratories
The NAC appreciates the efforts to establish D-Lab and related activities. However, it will not beeffective without dedicated full-time staff. If resources are not available the NAC recommends that
MLF promote a collaboration based D-lab, for example by outsourcing activities or functions touniversities. There are many scientists in Japan who can produce high quality deuterated samples,both chemical and biological. Their participation should be welcomed as it enlarges the community
base of MLF.
The NAC identified a number of specialist roles in the sample environment and computing groups
that were filled by contract staff, as opposed to employees. This poses a risk to the long term
success of MLF. Roles which require significant investment in training and experience should beprioritised to be recruited as employees.
2. Evaluate the appropriateness of the science promotion effortsa. Activities of science group and science promotion board
b. Any suggestions to help the smooth penetration of science driven atmosphere11 science groups have been created to encourage the development of a more science based, rather
than technique based, culture. For further development, these should have common objectives andbecome more active in interacting with community and promoting science with neutrons such as,
for example, holding meetings/seminars (including with external scientists). However, the NAC isconcerned that many members of each group are too busy to fulfil their main mission, e.g. runningtheir own instrument, working for the users, SE services etc. and they do not have enough time tomeet and discuss science.
3. Any suggestions for improvements are appreciated. Our particular concerns include but notlimited to the following:a. Yet to be unified MLF activities between JAEA, KEK, CROSS, and Ibaraki prefecture, as pointed
out at the last NAC
3See section 4.
b. Improving paper production rate
The transition from MLF construction to initial operation was a great success, particularly given thedisruption caused by the earthquake and other lengthy outages. 20 world class instruments havebeen made available to users. Now, in the regular operation phase, it is important to reorganize thetasks and identify dedicated experts for the different support areas. Instrument scientists, sampleenvironment, data acquisition and analysis, polarization analysis etc. all need additional resourcesand manpower to scale up the scientific outcomes.
Continued efforts must be prioritised to increase the paper production rate per experimentconducted. The current rate is well below the rates at other facilities such as SNS, ISIS and ANSTO.
In-line with standard practice at other facilities the NAC recommends not to differentiate between"refereed proceedings papers" and "refereed papers".
The production rate per instrument might, to some extent, reflect inexpert and new users. Having
new users is extremely valuable and demonstrates the attraction of JPARC, but it also induces aheavy overload on the scientists at the beamlines. In order to prioritize resources a more detailed
analysis is needed of which experiments do not produce outputs (both academic and industrial). Is
analysis software a limitation, sample preparation, scientific or technical support? An example ofwhat can be achieved is the case of iMATERIA, which is highly productive through the support of five
instrument scientists (which is actually high compared to international benchmarks). However, thelevel of resourcing is not consistent across the instrument suite and the NAC sees this as a major
obstacle in increasing the paper production rate.
c. Promotion of industrial use
The NAC continues to be impressed by the efforts to increase industrial use and output, and tobetter define and track non-publication outputs. The NAC commends the new industry/university
initiative “Research Group on Polymer Science under Humidity Conditions” and looks forward tofurther development of the MLF-industry relationship and to more visible outputs.
d. Direction of life science in MLF
MLF is producing some excellent scientific results in the life sciences using a variety of techniques,e.g. diffraction, small angle scattering and quasi-elastic scattering. Deuteration is indispensable forthese studies, and for many biological experiments the time/effort needed to produce the samples
is now considerably greater than the time/effort to perform the experiments. The importance of theD-lab has already been commented on.
The proposal for a new single crystal diffractometer for life sciences was presented to the NAC.
While this should in principle open up a higher proportion of the proteins in the PDB to study withneutrons, this still requires in practice the growth of suitably large crystals and the number ofstudies per year will still be limited. In addition, neutron studies do not add value to all structures.
The NAC would therefore recommend that the science case is much more focussed on (examples of)
specific scientific questions that can be addressed with available crystals. Consideration should also
be given to the effect that the rapid developments in electron microscopy will have in this scientificarea. In addition, now that MLF has a limited number of vacant beamlines (before a second target
station is built) the case for a specific instrument needs to be compared to other alternatives.
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e. User program handling and user support
The organisation of the user programme is steadily improving and this is reflected in the user
satisfaction questionnaires. However, the Single Sign-On application/registration system has notbeen completed. MLF should bring this into use as soon as possible so as to increase the activity andoutput, while lowering miscellaneous procedures/tasks.
f.

Second Target Station

The NAC is pleased to see effort in developing concepts and ideas for a second target station at MLF.
However, it is too early to provide detailed comments as ideas and concepts are at a very
preliminary stage.
The NAC would suggest that the second target station concept should provide for sufficiently
different and new capabilities compared to the first, which is a challenge since the current 25Hz
frequency was already a compromise between higher and lower frequencies, e.g. ISIS (50/10Hz) andSNS (60/15Hz). The plan should also consider the optimization of instruments across both targetstations in order to demonstrate the added value and capability to the scientific community. ‘Moreof the same’ is not likely to attract funding.
The NAC encourages the development team to devise realistic, buildable and easy-to-operatemodels for a muon source.
4. Additional remarks
Business model for MLF operation
Modern MW class neutron sources with suites of advanced instruments, such as MLF, have thecapability to continuously produce many significant scientific results. However, to achieve thisrequires an appropriate ‘business model’ for operation, i.e. organizational structure, staffing levels
and budget. The scale and complexity of the MLF operation are enormously different from KENS, forexample, the expectations of users are much higher and their requirements are more varied andmore demanding to execute, so the business model also needs to be different.
A significant scale up of the results achieved so far by MLF could be expected if the level of resources
is increased appropriately in areas such as sample environment, software/computing, detectors,
neutron devices etc. as well as instrument scientists. This support should be structured in specializedgroups providing a consistent level of support across the facility.
Instrument scientists should be enabled to concentrate on scientific support for users and producing
scientific outcomes, rather than on a broad range of technical and scientific tasks. This is especially
important as the demands on instrument scientists increases as a result of the increased beamline
throughput gained from increased source power. Despite the constraints of the separateorganizations (JAEA, KEK, CROSS, Ibaraki prefecture) all efforts should be made to provide a
consistent service to users within the general user or public beamtime. The external perception of a
facility, and its attractiveness for users and funding, is often set by the lowest performance level
rather than the highest, so it is in the interests of all the organizations comprising MLF to use theirresources in the most effective way to achieve consistency.
Cooperation with universities and industries, as has already been started, can further enhance theproductivity.
5Conclusion
It is clear that MLF staff are highly dedicated and working extremely hard towards the success of thefacility.
Steady well-considered progress is being made towards high power operation. This should becontinued.
MLF has an excellent suite of instruments that provide the capability to produce correspondingly
excellent science. However, the business model for operation of MLF needs to be appropriate to thetechnical capabilities of the facility if the potential scientific output is to be achieved.

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