[Neutron] J-PARC Project Newsletter No.89

Wed Jan 25 08:04:41 CET 2023

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　 J-PARC Project Newsletter
　　                       No.89, January 2023                                                                      
Japan Proton Accelerator Research Complex under joint operation 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]
*WE HOPE EVERYBODY COULD HAVE A HAPPY NEW YEAR AND WE WISH TO HAVE ANOTHER FRUITFUL YEAR WITH MANY SCIENTIFIC OUTPUTS.
*UK MINISTER FOR SCIENCE, RESEARCH AND INNOVATION VISITS J-PARC.
*THE CEREMONY TO CELEBRATE THE RENEWAL OF COOPERATION AGREEMENT IN THE FIELD OF SPALLATION NEUTRON SOURCE DEVELOPMENT BETWEEN J-PARC AND ESS ERIC (EUROPEAN SPALLATION SOURCE ERIC) WAS HELD AT ESS.

2. [Accelerator Division]
STABLE OPERATION OF THE ACCELERATORS FOR MLF USERS FROM NOVEMBER TO DECEMBER. BEAM COMMISSIONING IN THE MR HAS STARTED AT HIGH REPETITION RATE WITH NEW POWER SUPPLIES.

3. [Particle and Nuclear Physics Division]
*FIRST XI ATOMIC X-RAY MEASUREMENT USING A COUNTER-EMULSION HYBRID METHOD.
*FINISHING TOUCHES TO THE START OF THE NEUTRINO BEAM OPERATION.
*STATUS OF THE JSNS2 / JSNS2-II (SEARCHING FOR STERILE NEUTRINOS AT J-PARC MLF, E56 / E82).
*STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET).
*STATUS OF THE MUON g-2/ ELECTRIC DIPOLE MOMENT (EDM) (E34).

4. [Materials and Life Science Division]
*EXTENDED MLF OPERATION SCHEDULE IN THE 2022B PERIOD.
*MAINTENANCE WORKS DURING THE SUMMER OUTAGE WERE COMPLETED AND THE BEAM OPERATION STARTED ON SCHEDULE.
*PROPOSALS FOR 2023A PERIOD WERE RECEIVED.
*THE NEUTRON AND MUON SCHOOL WAS HELD IN A HYBRID STYLE.
*THE PLANNED MUSE MAINTENANCE WORKS WERE COMPLETED AND THE MUON TARGET AND ALL BEAMLINES OPERATED SMOOTHLY.

5. [Nuclear Transmutation Division]
THIRD CAMPAIGN OF CORROSION EXPERIMENT SUCCESSFULLY COMPLETED.

6. [Safety Division]
AN EMERGENCY DRILL WAS HELD ASSUMING RADIATION EXPOSURE ACCIDENT

7. [Information]

8. [Editorial Note]
BEAM COMMISSIONING OF THE MAIN RING WAS FURTHER POSTPONED 

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1. [Overview] by Takashi KOBAYASHI
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WE HOPE EVERYBODY COULD HAVE A HAPPY NEW YEAR AND WE WISH TO HAVE ANOTHER FRUITFUL YEAR WITH MANY SCIENTIFIC OUTPUTS.
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 Recently, although the COVID pandemic doesn’t show signs of subsidence yet, social/research activities are getting back to normal with appropriate preventive measures against COVID spread. 
 International researchers are coming back to J-PARC, for example, for construction work of the T2K near neutrino detector upgrade. We are thrilled to welcome our international friends back to J-PARC. 
Face-to-face meetings/workshops/conferences restarted also at J-PARC. An example is the workshop on “Development of fundamental physics using neutron” (https://kds.kek.jp/event/43680/). 
 Also, around J-PARC, face-to-face PR activities have restarted in various local events for the general public, for example, in “Ozora Marche” https://ozoramarche.com/ (sorry, but only in Japanese) in front of Muramatsu shrine.
 We realized the impact and importance of direct face-to-face communication.

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UK MINISTER FOR SCIENCE, RESEARCH AND INNOVATION VISITS J-PARC.
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https://www.kek.jp/en/topics-en/202212161205/
 On December 14th, George Freeman MP, UK Minister for Science, Research and Innovation, Department for Business, Energy and Industrial Strategy, and his delegation visited J-PARC. Minister Freeman gave a short speech in front of the staff and users at J-PARC: “This kind of research is not only hugely inspiring to people, but also goes to the heart of our humanity. It also brings technological developments to a new generation. I am delighted to announce that the UK has decided to allocate extra funding for the HK project.”

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THE CEREMONY TO CELEBRATE THE RENEWAL OF COOPERATION AGREEMENT IN THE FIELD OF SPALLATION NEUTRON SOURCE DEVELOPMENT BETWEEN J-PARC AND ESS ERIC (EUROPEAN SPALLATION SOURCE ERIC) WAS HELD AT ESS
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https://j-parc.jp/c/en/topics/2022/12/16001087.html
 The renewed cooperation agreement between the J-PARC Center and ESS in spallation neutron source development was signed on June 8, 2022. 
 On October 10, a ceremony was held in Lund, Sweden, where ESS is located, in the presence of the Japanese Ambassador to Sweden, Mr. Noke Masaki, to mark the extension of the agreement. At that time, the signed agreement was handed over between Dr. Kobayashi, Director of the J-PARC Center, and Dr. Schober, Director General of the ESS.
 In conjunction with the ceremony, a Commissioning Workshop of the ESS-J-PARC collaboration was held, face-to-face, at ESS. ESS is entering the commissioning phase, and the J-PARC experiences could be useful for ESS commissioning. On the other hand, the J-PARC commissioning took place more than 10 years ago so that many young researchers at J-PARC never experienced any of its commissioning activities. Therefore, this kind of international workshop to share experiences and information is beneficial for both sides. Very active discussions were held during the workshop.
https://indico.esss.lu.se/event/3079/overview

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2. [Accelerator Division] by Michikazu KINSHO
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STABLE OPERATION OF THE ACCELERATORS FOR MLF USERS FROM NOVEMBER TO DECEMBER. BEAM COMMISSIONING IN THE MR HAS STARTED AT HIGH REPETITION RATE WITH NEW POWER SUPPLIES.

 A new operation run was started in November after the summer shutdown. Accelerator studies at the beam current of 50 mA were carried out at the linac. The studies were also performed at the 3 GeV Rapid Cycling Synchrotron (RCS) with a linac beam current of 50 mA for user operation. The main purposes of the studies were to startup the machine, reproduce the accelerator parameters, to confirm the performance of some new components installed during the summer shutdown, to survey new parameters for lower beam loss, etc. Beam studies of linac and RCS studies have been performed until November 18th.
 Beam user operation for the MLF users was started on 21st November as scheduled with beam power of 780kW, which was smaller than the power before summer shutdown. Then, on 30th November, the frontend of the linac was retuned and the beam power was restored to 800 kW to the MLF. The user operation could be continued with high availability of more than 90%.
 Beam commissioning of the Main Ring (MR) was postponed to 12th December from original schedule of 19th November due to the delay of tunning of new power supplies. There is currently no change to the scheduled start of the neutrino user operation in middle January. [schedule is postponed further, see the editorial note.] 

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3. [Particle and Nuclear Physics Division]  
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THE FIRST Xi ATOMIC X-RAY MEASUREMENT USING A COUNTER-EMULSION HYBRID METHOD (Mamami FUJITA)
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 Study of nuclei containing an Xi- hyperon, which contains two strange quarks, is important to understand general baryon interactions and the equation of state of neutron star. The X-rays from Xi atoms have fruitful information about interactions between Xi and nucleus, since the energy levels of an Xi atom and their widths are modified by the strong interactions between Xi and nucleus.
Historically, the study has been performed using missing-mass spectroscopy and nuclear emulsion experiments, but their interactions are still unclear, since the information of existing data is very limited. Thus, we developed a new approach using measurements of X-rays from Xi atoms. 
 The J-PARC E07 experiment was conducted at J-PARC K1.8 beam line, which provides the K- beam necessary for Xi production via the p(K-, K+)Xi- reaction. The experimental difficulty is that most of Xi-s decay before stopping and such decays make a significant background in the X-ray spectrum. To reject these background photons, we developed a hybrid method using three detector systems: magnetic spectrometers for identification of the (K-, K+) reaction, nuclear emulsion for Xi tracking, and Ge detectors for X-ray measurement.
The background level was drastically reduced to a level of 1/170 by applying this triple coincidence measurement. Unfortunately, no X-ray peak was observed with the current statistics. We found that five times larger statistics are needed. Such statistics will be obtained in a future experiment.

(DOI)
https://doi.org/10.1093/ptep/ptac156

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FINISHING TOUCHES TO THE START OF THE NEUTRINO BEAM OPERATION
(by Yoshiaki FUJII)
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 Beam operation is scheduled to start-up on January 12, 2023. [schedule is postponed further, see the editorial note.] The beam group of the neutrino experimental facility is doing the last work to finish up the system.
 The primary beamline had installation of the last beamline component on 10/24. The super-conducting system is now under cooling, and the whole of the primary beamline system will establish beam-ready by 1/10, 2023.
 The major work at the secondary beamline is the installation of a new target and new horns #1 and #2. Their installation was completed, and excitation tests of the new horns at 320kA were successfully done on 12/9. All works in the helium vessel were completed, and the vessel was closed for evacuation to fill it up with helium.
 In the ND280 facility, new detectors SFGD, HATPC, and ToF counters will be installed to reduce the uncertainty of the neutrino interaction. Assembly work of the SFGD (Super Fine-Grained Detector) is in progress at J-PARC. SFGD is an array of two million scintillator cubes with sizes of 1cm x 1cm x1cm. The stacking process of two-million cubes was completed, and people are working on assembling the enclosure box. Presently two-million cubes are supported in place with fishing lines. These will be replaced with WLS fibers in January.
 Hyper-K had a collaboration meeting from 10/17 to 10/28 online and had HK-PAC from 11/11-11/17 also online.

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STATUS OF THE JSNS2 / JSNS2-II (SEARCHIING FOR STERILE NEUTRINOS AT
J-PARC MLF, E56 / E82) ( by Takasumi MARUYAMA )
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 The JSNS2 (E56) / JSNS2-II (E82) collaboration searches for the neutrino oscillation over a short distance with the sterile neutrinos at J-PARC MLF.
 For the JSNS2, the new electronics developed by University of Michigan are being tested using the LED calibration system at the near detector storage area in J-PARC on Dec-2022. The new electronics are working and seeing the LED light well. Immediately after the reinstallation of the near detector on the 3rd floor of MLF in 2023, the new electronics will be tested with the real liquid scintillator. For the JSNS2-II, the approval of Japanese fire law to construct the new far detector, located outside of MLF at a baseline of 48 m, was obtained. There have been two J-PARC wide safety committee meetings on JSNS2-II from September to November in 2022. The safety on the PMT installation was discussed extensively so far, and the work was approved after several countermeasures were made. The other hardware such as the production of the acrylic tank has been progressing as well. JSNS2-II aims to start the data taking within FY2023.

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STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET)
(by Satoshi MIHARA)
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 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 and detector construction work continues; after installing the primary proton beamline apparatus including a target chamber and mask system for beam transport study of the curved solenoid magnet, the shieling of the primary proton beamline was closed with shielding blocks in December as part of the radiation protection from the target and beam dump. Air lock shielding above the shielding blocks
was also prepared for preventing radioactive air diffusion from the primary beamline area.
 The COMET collaboration is making intensive efforts to prepare the beam studying system for the COMET Phase-alpha, the engineering run, scheduled in JFY 2023. The system is composed of charged particle trackers and range counter to measure the beam profile and particle contents in the secondary beam. Beam extinction monitor based on a new semiconductor technology will also be tested in Phase-alpha. It is also an important issue to survey environmental radiation such as neutrons and gammas to clarify the detector operating conditions.

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STATUS OF THE MUON g-2/ ELECTRIC DIPOLE MOMENT (EDM) (E34)
(by Tsutomu MIBE)
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 The E34 collaboration aims for precision measurements of the muon anomalous magnetic moment and electric dipole moment.
 The radiation shielding blocks and walls were fabricated and installed at the H-line. For the preparation for extension beyond the MLF building, the re-location of the buried cables was completed. The relocation of drainage water piping in the area of the H-line of the experimental building is in preparation. The areal plan for the building is refined in the working group under the J-PARC center. The collaboration continues to develop the experimental apparatus.
There are two publications,
 1) Modeling the diffusion of muonium in silica aerogel
     (C. Zhang et al., NIM A 1042 167443(2022))
 2) High-power test of an interdigital H-mode drift tube linac
     (Y. Nakazawa et al., PRAB 25, 110101 (2022)).

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4. [Materials and Life Science Division] by Toshiya OTOMO
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 EXTENDED MLF OPERATION SCHEDULE FOR THE 2022B PERIOD
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 Upon the approval of supplementary budget, J-PARC has reviewed its operation schedule and decided to extend the MLF user operation until the middle of March.
(https://mlfinfo.jp/en/announce/221209.html)

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MAINTENANCE WORKS DURING THE SUMMER OUTAGE WERE COMPLETED AND THE BEAM OPERATION STARTED ON SCHEDULE
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1) Neutron Source
 On September 26th, specimens were cut out from the fore front wall of the used target vessel which was operated with 836 kW at maximum. This time, the specimen of the inner wall of the mercury vessel, which was protected against the pitting damage by micro-bubble injection into mercury flow, could not be obtained, because the specimen fell into the mercury vessel. But, the damage on the specimen of the outer wall of the mercury vessel, the mercury boundary wall, was negligibly small, which was a promising result for the stable beam operation with greater beam power. On October 11th, the used mercury target vessel was replaced with a new one which had the same structure of the mercury flow channel. 
 On November 21th, the user program started with 780 kW, which was a little bit less than the former power due to the trouble of the accelerator component, and the stable beam operation has continued with the availability of over 90%.

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PROPOSALS FOR 2023A PERIOD WERE RECEIVED
THE NEUTRON AND MUON SCHOOL WAS HELD IN A HYBRID STYLE
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2) Neutron Instruments and Science
 The MLF 2023A call for proposal on general use (short-term and one-year) was closed on November 7th. We have received 277 neutron proposals including 4 new user promotion proposals and 1 one-year proposal. All the proposals are now under review process, whose results will be announced around February 2023.
( https://mlfinfo.jp/en/user/proposals/2023A/)
 The 6th Neutron and Muon School (NM-school) was held December 12th-16th in a hybrid style, with lectures online/on-site and hands-on training on-site. The school provides lectures and practical training for newcomers to neutron and muon beam research. The 18 on-site participants experienced beam-on experimental practices and data analyses on neutron/muon instruments at J-PARC MLF or JRR-3 (a research reactor of JAEA in operation at 20 MW), where two facilities are located adjacent to the JAEA Tokai area.
(https://mlfinfo.jp/sp/school/6th-nms/index.html)
The recent scientific press releases at MLF from neutron instruments were issued as follows:
(1) “Magnon mode transition in real space”
https://doi.org/10.1038/s41598-022-22555-9
(2) "Partial breakdown of translation symmetry at a structural quantum critical point associated with a ferroelectric soft mode"
https://doi.org/10.1103/PhysRevB.106.134111
(3) "Non-Hookean large elastic deformation in bulk crystalline metals"
https://doi.org/10.1038/s41467-022-32930-9
It was selected as one of the featured articles by the editor.

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THE PLANNED MUSE MAINTENANCE WORKS WERE COMPLETED AND THE MUON TARGET AND ALL BEAMLINES OPERATED SMOOTHLY
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3) Muon Science Facility (MUSE)
 After the summer shutdown in 2022, MUSE resumed operation on November 21st, 2022, as scheduled. The planned maintenance works were completed and the muon target and all the beamlines operated smoothly to conduct the user experiments. 
 The rotating feeder unit of the muon production target was replaced in the summer maintenance. The old unit had trouble with the rotating torque turbulence due to the high accuracy requirement between two rotating shafts, and a more flexible one was newly adopted. With this replacement work, the interlock of the target was reviewed, and the new way could reliably find the signs of failure by monitoring the increase in the motor torque overlong periods. So far, the target has been operating smoothly up to the present.
 In the D line, the final focusing magnets of the quadrupole triplet and their power supplies for the D1 area were replaced with new ones to provide a higher momentum beam. The commissioning was performed just after the beam resumption and confirmed the beam transport. This will extend the muon use.
 The results in D2 were presented to the press: “Volatile analysis of the Hayabusa2 asteroid Ryugu sample revealing volatile sources and recent surface evolution” has been published in “Science”(https://www.science.org/doi/10.1126/science.abo0431), and “Muon experiment reveals more detail of asteroid Ryugu” especially about the elemental analysis by a negative muon beam.(https://doi.org/10.1126/science.abn8671)
 The result in D1 was presented to the press: “Direct Measurement of the Evolution of Magnetism and Superconductivity toward the Quantum Critical Point” (https://doi.org/10.1073/pnas.2209549119).
 The 7th symposium on research on arts and sciences integration was held at the KEK Tsukuba campus on October 2nd-3rd.
  MUSE received 41 muon proposals for the 2023A periods, and the review process for these proposals is now underway.

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5. [Nuclear Transmutation Division] by Hironari OBAYASHI
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THIRD CAMPAIGN OF CORROSION EXPERIMENT SUCCESSFULLY COMPLETED

 Accelerator-driven transmutation system (ADS) proposed by JAEA uses a lead-bismuth eutectic alloy (LBE) for spallation target and reactor coolant for the good neutronic performance for ADS. However, LBE has an issue of compatibility with standard reactor materials. LBE has the specific characteristic to dissolve out elements from steels and that drastically decreases the lifetime of the structural materials. A recommended method to solve this issue is to suppress the dissolution of elements in steel by controlling the oxygen concentration (OC) in LBE, which is studied worldwide. In this approach, an oxide film is formed on the steel surface by controlling OC to an appropriate range, thus avoiding direct contact between LBE and the steel. Under conditions where high-temperature LBE (400°C or higher) flows, oxygen is consumed by the growth of oxide film hence OC is constantly decreasing. OC in LBE is managed by intermittently supplying a mixture gas containing trace amounts of oxygen to a pure argon carrier gas to compensate for the consumed oxygen. The control sequence of OC was automated and installed into “OLLOCHI”, a corrosion test loop with high-temperature LBE. Since November 2020, the corrosion test campaign has been performed by using OLLOCHI.
 The planned annual operation time of JAEA's ADS is around 7,000 hours, however, the duration of previous two campaigns for the purpose of functional test of OLLOCHI was shorter than that. The third campaign started in October, 2021 as a substantial corrosion experiment for LBE application to ADS. Flow velocity at the test section was 1 m/s. The temperatures of the hot and cold legs of the LBE flow channel are 450°C and 350°C, respectively. A target control value of OC was set to one micro wt%. Three specimen holders, which stored 26 corrosion test specimens in one holder, were prepared to perform time dependent corrosion tests by changing exposure time for 2,000 hours, 5,000 hours, and 7,000 hours. During the campaign, the control system of OC worked well, and as a result, the OC was maintained around one micro wt% for more than 7,000 hours. Hence the third campaign of corrosion experiment was successfully completed. The post examinations of the obtained specimens including those of previous campaigns are being performed in parallel to check the compatibility of materials exposed to flowing high-temperature LBE.

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6. [Safety Division] by Yoshihiro NAKANE and Kotaro BESSHO
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AN EMERGENCY DRILL WAS HELD ASSUMING RADIATION EXPOSURE ACCIDENT
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 An emergency drill was held on Oct. 25 at the Materials and Life Science Experimental Facility (MLF).
 It was assumed that the beam operation was started without evacuating a worker in an experimental area of MLF and he was exposed to radiation.  The drill included contamination survey and transportation of the exposed worker, estimation of exposure dose, setup of the command post and communication with accidental site, report to headquarters via TV conference, and simulated press release.

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FISCAL 2022 J-PARC SAFETY AUDIT
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 The fiscal 2022 J-PARC safety audit was conducted by two auditors on Nov. 28th. They reviewed the points: 1) Organizational structure for safety management, 2) Safety management in works, 3) Emergency responses, and 4) Fostering and maintaining safety education and safety culture. The auditors gave us valuable recommendations, such as importance of looking back at completed works, thinking about margin for work schedules, and classification of acceptable minor troubles and accidents that must not happen.

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7. [Information] 
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8. [Editorial Note]
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BEAM COMMISSIONING OF THE MAIN RING WAS FURTHER POSTPONED 
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Beam commissioning of the Main Ring (MR) was postponed to late January 2023 from 12th December due to the failure of the beam extraction magnet which occurred after the article compilation date (middle of December). 　The scheduled start of user operation of the MR will be determined according to the results of the beam commissioning and it is decided there will be no neutrino beam operation until the end of March.

Past issues are available from the link below.
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 at jaea.go.jp 
┃ Takatoshi MORISHITA: morishita.takatoshi at jaea.go.jp
┃ Jean-Michel POUTISSOU (English Editor): jmp at triumf.ca 
┃ Chiaki SHIRAISHI (Secretary): shiraishi.chiaki at jaea.go.jp
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