[Neutron] J-PARC Newsletter No. 82

Thu May 20 09:34:27 CEST 2021

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     J-PARC Project Newsletter
                                                   No.82, April 2021
Japan Proton Accelerator Research Complex under operation jointly by the High Energy Accelerator Research Organization (KEK) and the Japan Atomic Energy Agency (JAEA)
http://j-parc.jp/index-e.html

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HEADLINES AND CONTENTS

1. [Overview]

   NEW FISCAL YEAR WITH NEW MANAGEMENT.

2. [Accelerator Division]

   OPERATION STATUS OF THE ACCELERATORS.
   ACCELERATOR TECHNICAL ADVISORY COMMITTEE (A-TAC) MEETING.

3. [Particle and Nuclear Physics Division]

   RECENT BEAM TIME AT THE HADRON EXPERIMENTAL FACILITY.
   NEUTRINO EXPERIMENTAL FACILITY STARTED BEAM OPERATION SUCCESSFULLY.
   STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET).
   STATUS OF THE MUON G-2/ ELECTRIC DIPOLE MOMENT (EDM) (E34).
   STATUS OF USER OPERATION.

4. [Materials and Life Science Division]

   THE BEAM OPERATION OF MLF IS GOING WELL WITH 600 kW.
   QUANTUM BEAM SCIENCE FESTA WAS HELD ONLINE.
   MUSE CONTINUES TO SAIL OVER TROUBLED WATER.

5. [Nuclear Transmutation Division]

  TEF TECHNICAL ADVISORY COMMITTEE MEETING WAS HELD.

6. [Safety Division]

  FISCAL 2020 J-PARC SAFETY AUDIT.

7. [Editorial Note]

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1. [Overview] by Naohito SAITO
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  NEW FISCAL YEAR WITH NEW MANAGEMENT

     This is my last contribution to the newsletter as a director of J-PARC Center. (Actually, already an ex-director.) 
     As reported in the rest of this issue, J-PARC has managed to make a good progress in all fronts of the facilities while our fight against the COVID-19 continues. The progress could have been much more fruitful, if we could be fully open to all users from all over the world. It may take some time to fully recover our research environment from before the pandemic. We will explore further the potential of J-PARC with the new decadal plan, which has already started with the replacement of the power supply for the Main Ring towards higher repetition rate. After the completion of the power supply upgrades, we wish to recover the beam time at the MR towards full nine cycles. At the same time, the beam power at MLF will be enhanced gradually towards 1 MW for more science production.
     When you receive this newsletter, the J-PARC management will be already renewed and will be led by the new Director, Dr. Takashi KOBAYASHI. I would like to take this opportunity to thank all involved in the J-PARC activities for their dedicated contributions towards the creation of science at the world-leading high-intensity proton accelerator research complex. I am fully convinced that progress of J-PARC will be further accelerated under new management! 
     Stay healthy and stay connected. We would like to share more excitements at J-PARC! 

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2. [Accelerator Division] by Michikazu KINSHO
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  OPERATION STATUS OF THE ACCELERATORS

     After the New Year's holiday, the beam operation started on January 7 as a continuous operation run of Run#86. The user program resumed for the Materials and Life Science experimental facility (MLF) on January 12. The beam power was 600 kW which was the same as the previous user operation up through December. The user program was rather smooth for the MLF until the end of March.
     For the Main Ring synchrotron (MR), since the hadron user program was postponed to the middle of February due to a cooling water failure in the hadron facility, the schedule was changed, and some of new power supply installation work has been done by February 7th, the beam operation started on February 8th with slow extraction for the hadron user operation. The beam power was gradually increased to 60 kW which was the maximum beam power for the hadron user operation in J-PARC. The user program was smooth until February 28th, when the ESS#1 (Elector Static Septum #1) had a failure as follows. Quadrupole magnets on three straight sections stopped unexpectedly due to the accidental malfunction of the 22kV circuit breaker, and the circulating beam orbit deviated largely. It caused a large beam loss and broke some of the ESS#1 ribbons. Short circuit failure of the ESS#1 happened, caused by the broken ribbons. Almost all of the lost beam spread out through the whole of the Main Ring, and only a small frac ion of beam was extracted to the hadron target (no temperature rise was observed on the target). It was impossible to continue the hadron user operation. Until the spare ESS is ready, we replaced the broken ESS#1 with a vacuum pipe and started the neutrino user operation. We have investigated the cause of malfunction of the circuit breaker in parallel. After identifying the cause and taking countermeasures, we restarted the hadron user operation. The neutrino user operation was started on March 8th at the beam power of 510kW, and it was stopped on March 19th for preparing to restart the hadron user operation which will be started on March 27th.
     The availability in the Japanese Fiscal Year 2020 (from April 2020 to March 2021) was high, more than 90 percent for the MLF since we had no serious troubles at the linear accelerator (linac), the RCS and the MLF. The availability of the MR user operation was not so high (less than 70% for the hadron user operation). The cause of lower availability of the MR user operation was the ESS#1 failure in March as described above.

  ACCELERATOR TECHNICAL ADVISORY COMMITTEE (A-TAC) MEETING

     The 20th A-TAC meeting was held remotely on February 1st to 4th. There were nine committee members, all the members attended and 12 reports were presented such as required items from last ATAC, operational status, and performance upgrade. The committee deliberated the improvements, directivity, etc. and gave recommendations.

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3. [Particle and Nuclear Physics Division] by T. TAKAHASHI and K. OZAWA
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  RECENT BEAM TIME AT THE HADRON EXPERIMENTAL FACILITY (by T. Nomura, T. Takahashi, K. Ozawa) 

     The slow-extraction of the Main Ring for the Hadron Experimental Facility was conducted from December 14 to December 22, 2020 and from February 8 to February 28, 2021. In these operation periods, we started measurements of X rays from Xi- atoms and performed detector tests for an H-Dibaryon search experiment at the K1.8 beam line. The X-ray measurements aim to study Baryon-Baryon interactions in the Strangeness S=-2 sector. Especially, we can expect having direct information on the Xi-Nucleus optical potential in a peripheral part of a nucleus. We will resume our beam time in late March and finish the data taking of the X-ray experiment.
     The KOTO experiment continued their data acquisition to search for K_L to pi0 nu nu-bar decays at the KL beam line. In December 2020, a new detector, called Upstream Charged Veto (UCV), was installed at the entrance of the KOTO detector to reduce backgrounds due to contamination of charged kaons in the neutral beam. Its performance was evaluated with the beam in February 2021 and the result confirmed that UCV can provide a rejection power against the backgrounds as expected.
     Also, a new experiment at the B line started to measure mass modifications of vector mesons in a nucleus. The new experiment took data for setting up detectors and their calibrations.
     We also planned to have further beam time in May and June. In that time, we will carry out the H-Dibaryon search experiments, the KOTO experiment, and pilot data acquisitions of the new B-Line experiment.

  NEUTRINO EXPERIMENTAL FACILITY STARTED BEAM OPERATION SUCCESSFULLY （by Y. Fujii)

     After a one-year long maintenance period, the neutrino experimental facility started beam operation from March 8th. Starting up with low beam power for vacuum baking, it eventually reached 510kW stably. On March 19th, radiation inspection under operation was successfully done, and the beam operation has been suspended to switch to the hadron beam operation. Neutrino beam operation will be resumed on April 8th, and continue until late April.
     T2K experiment was carried out without the off-axis detector ND280 operation due to COVID travel restrictions. Three near detectors, Wagasci, BabyMIND, on-axis INGRID, were operated with on-site experts of Japanese institutes and remote watch and monitoring by institutes overseas. The far-detector SuperKamiokande operated with gadolinium successfully for the first time with beam and showed improved capability of neutron detection.
     One of the most important sub-detectors of the ND upgrade program, SuperFGD, finished assembly of two million scintillator cubes with supporting fibers.
     The NINJA experiment aims at precise measurement of neutrino-nucleus interactions with nuclear emulsion detector and scintillator detectors. They successfully conducted a pilot run with their new heavy-water target. NINJA will keep detector operation through the beam-off period for cosmic-ray measurement.
     The JSNS2 experiment searches for sterile neutrinos with the short baseline neutrino oscillations from nu_mu_bar to nu_e_bar at MLF. It started a long physics run from January 2021 and is taking data smoothly. This data taking period will continue until July. They did an on-line press release on February 9th on the physics goals and successful start of their data taking. Please visit     https://j-parc.jp/c/press-release/2021/02/03000646.html  (Japanese only)

  STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET) (by S. MIHARA)

     The COMET experiment aims to search for the lepton-flavor violating muon reaction, mu-e conversion, with a sensitivity better than 10^{-14} in Phase I.
     Facility construction work continues; construction of the proton beam dump and radiation shielding wall in the COMET experiment area has made great progress. In addition to this, curing of the floor surface has been completed to locate a heavy radiation shielding to be installed in the capture solenoid.
     The collaboration has been intensively working toward integrating sub-detector components into a mu-e conversion search detector. Final assembly design of the main detector for physics, composed of Cylindrical Drift Chamber (CDC) and Cylindrical Trigger Hodoscope (CTH), is in progress with detailed setting layout of cables and gas transfer tubes. Assembly of another system for beam diagnostics, composed of the straw-tube tracker and LYSO calorimeter, has been initiated by the collaboration.
     The COMET collaboration has completed preparation of an 8-GeV acceleration and beam extraction test to measure the beam extinction factor in the Hadron hall. This was originally scheduled in early 2021 but it was postponed to May due to the change of accelerator operation schedule. This will be an important milestone for the COMET collaboration to achieve its target sensitivity. 

  STATUS OF THE MUON G-2/ ELECTRIC DIPOLE MOMENT (EDM) (E34) (by T. MIBE) 

     The E34 collaboration prepares for precision measurements of the muon anomalous magnetic moment and electric dipole moment.
     KEK is preparing for a funding request of base facilities, building and utilities. As a part of the preparation, KEK has completed the ground survey, survey for buried cultural properties, engineering design of re-location of underground properties below the new experimental building. Detailed design of building and utilities are in progress.
     The collaboration is working on construction of the experimental equipment. Demonstration of laser ionization of muonium for the thermal energy positive muon source is in preparation. The experimental setup for the cooled muon source diagnostics was built in the new experimental area (S2 area) in J-PARC MLF. The design of the IH-DTL cavity and DAW cavity has been developed. Fabrication of these will be started in FY2021. 

  STATUS OF USER OPERATION (by T. KOBAYASHI, T. KOMATSUBARA) 

     The slow-extraction (SX) of Main Ring for the Hadron Experimental Facility was conducted from February 8 to 28, 2021, and the fast-extraction (FX) for the Neutrino Experimental Facility was conducted from March 8 to 19. More operation of SX and FX is scheduled before the long shutdown starting from this summer.

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4. [Materials and Life Science Division] by Toshiya OTOMO
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  THE BEAM OPERATION OF MLF IS GOING WELL WITH 600 kW

1) Neutron Source
     The beam operation of MLF is going very well with 600 kW and the beam power is going to be increased to 700 kW from this April. Due to the alarm that indicated the shaft abrasion of the water pump used for cooling of muon target devices and the magnets of proton beam transport line, the user program was suspended from January 21st to 24th, but the pump system was recovered and is running without any trouble now. 
     The target system workshop with SNS of Oak Ridge National Laboratory is going to be held online on Tuesdays and Thursdays every week from March 23rd to April 8th. The time is from 8:30 to 10:00 in Japan. The major topics will be R&D for the high power target and moderator, remote handling, and research collaborations etc.

 QUANTUM BEAM SCIENCE FESTA WAS HELD ONLINE

2) Neutron Instruments, Science and Technology
     The international neutron advisory committee (NAC) has been held in February 17th and 22nd by online discussion. The report from the MLF on updated status of the neutron target and infrastructure, neutron instruments and their outcomes, industrial use, and so on, were summarized. In particular, comments and suggestions on the activities under COVID-19 were given from the committee members according to MLF request. The committee evaluated the MLF handling of experiments during the situation generally good, and we could also share the knowledge about sample transportation and remote control experiments.
     Quantum Beam Science Festa (QBSF-2020) which is a yearly event for domestic users for MLF and IMSS (Institute of Material Structure Science in KEK) was held online on March 9th ? 11th together with the 12th MLF symposium (also with the 38th PF symposium). 273 posters involving scientific achievements, device developments, and facility reports were presented in addition to invited oral lectures.
     Three recent notable scientific publications at MLF were as follows;
     (1) https://doi.org/10.1093/ptep/ptaa169
     (2) https://doi.org/10.1038/s41467-020-20859-w
     (3) https://doi.org/10.1038/s41467-021-21351-9
     The arrangement between KEK, JAEA, CROSS( the Comprehensive Research Organization for Science and Society ) and ANSTO (The Australian nuclear science and technology organization) for cooperation on research and development in the field of neutron scattering science has been concluded on February 8th. Establishing the center of neutron research through this partnership, the promotion of neutron science, neutron technology, and exchange of human resources and ideas can be widely spread in the Asia-Oceania area.
     The new arrangement between KEK and JAEA and STFC on cooperation in the field of the development of neutron science technology was officially concluded by adding CROSS as a new Party, and is effective retrospectively from 11th January 2021, and will continue for 5 year period. We can expect close cooperation based on this arrangement.

  MUSE CONTINUES TO SAIL OVER TROUBLED WATER

3) Muon Science Facility (MUSE)
     The start of the New Year in Japan was marked by the declaration of a state of emergency (on January 7th, 2021) in response to the rapid spread of COVID-19 infection towards the end of 2020. The restart of MUSE also began with a problem (leak) in the vacuum pumping system of the proton beamline in addition to the cancellation of experiments due to the declaration. Fortunately, the vacuum leak was quickly solved by replacing a part of the pumping system, and the impact on beam time was minimized with the cooperation of the Accelerator Division. However, the beam time was soon subjected to cancellation due to a trouble of the pump of 3NBT, for which the staff were hectic to readjust the experimental schedule. After a four-day shutdown, the target resumed operation after it was determined that the trouble could be addressed with temporary measures. As of March, the user experiments have been maintained by constant adjustments, although the users’ visit to J-PARC is still restricted to prevent the spread of COVID-19.
     In January and February of every year, there is a flurry of committee meetings for experimental proposal review, international evaluation, etc. However, under the declaration of the state of emergency, all of these meetings were held online.
     The Muon Advisory Committee (MAC) was held as a succession of several online meetings, where those including foreign MAC members were arranged separately in the early midnight (JST) to minimize the impact of time differences. In the report, while the progress in the construction of H line and S2 area was appreciated, the lack of spare equipment for muon production target was raised as a serious concern to be communicated to the J-PARC management as one of the priority issues for MUSE.

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5. [Nuclear Transmutation Division] by Toshinobu SASA
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  TEF TECHNICAL ADVISORY COMMITTEE MEETING WAS HELD

     The seventh TEF (Transmutation Experimental Facility) Technical Advisory Committee (T-TAC) meeting was held via online meeting on January 22, 26, and February 2 in 2021. Three Japanese members and three foreign members from Belgium and Germany gathered to review the current progress of the TEF facility plan and related research and development work. 
     In the first and second day, J-PARC staff introduced the activities to realize the experimental facility, such as the technologies for Lead-Bismuth Eutectic alloy target and instrumentation, safety issues, neutronics and accelerator technologies. After the closed discussion on the final day by the TAC members, various recommendations and comments to advance the R&D activities were introduced at the end of the meeting. T-TAC suggested that the R&D works carried out by J-PARC as valuable contributions to the international ADS (Accelerator-driven transmutation system) community. T-TAC also recommends that the R&D topics addressed by the team are in line with the needs for designing and constructing the experimental facility. The summary report was delivered at the end of February 2021 to push forward the R&D for facility design.

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6. [Safety Division] by Kotaro BESSHO and Yoshihiro NAKANE
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  FISCAL 2020 J-PARC SAFETY AUDIT

     The fiscal 2020 J-PARC safety audit was conducted by two auditors on Dec. 7th. They reviewed the points: 1) Organization of safety management, 2) Management of work safety, 3) Emergency preparedness, and 4) Safety education and promotion and continuation of safety culture. On-site inspection of the works at the MLF facility was also conducted. The auditors gave us valuable recommendations on safety measures with a consideration of the development of J-PARC over the next 10 years.

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7. [Editorial Note]
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Past issues are available from the below link.
http://j-parc.jp/c/en/topics/project-newsletter/index.html

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Editorial Board:
Toshifumi TSUKAMOTO (Chair): toshifumi.tsukamoto at kek.jp 
Kaoru SHIBATA: shibata.kaoru@ jaea.go.jp 
Takatoshi MORISHITA: morishita.takatoshi at jaea.go.jp
Dick MISCHKE (English Editor): mischke at triumf.ca 
Keiko NEMOTO (Secretary): nemoto.keiko at jaea.go.jp
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