[Neutron] J-PARC Newsletter No. 85

Wed Feb 9 08:28:43 CET 2022

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     J-PARC Project Newsletter No.85, January 2022 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]

J-PARC OPEN HOUSE HELD ONLILNE ON NOV. 13th.
DETAILED DESIGN OF NEW ACCESS ROAD WILL BE MADE IN JFY2022.
J-PARC INTERNATIONAL ADVISORY COMMITTEE (IAC) WILL BE HELD ON MARCH 3 AND 4 ONLINE.

2. [Accelerator Division]

STABLE OPERATION OF THE ACCELERATORS FROM OCTOBER TO DECEMBER.

3. [Particle and Nuclear Physics Division]

ACCURATE MEASUREMENT OF DIFFERENTIAL CROSS SECTIONS OF SIGMA^{-}-PROTON ELASTIC SCATTERING.
IN THE T2K COLLABORATION MEETING, EXTENSIVE DISCUSSION WAS HELD ON PHYSICS OUTCOME AND UPGRADE PROGRAM CHALLENGES.
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]

THE MAINTENANCE WORKS DURING THE SUMMER OUTAGE HAVE BEEN CARRIED OUT CAREFULLY AND SUCCESSFULLY.
PROPOSALS FOR 2022A PERIOD WERE RECEIVED.
A LONG SUMMER OF MAINTENANCE & CONSTRUCTION WORK FOLLOWS.

5. [Nuclear Transmutation Division]

CORROSION EXPERIMENT GOES TO THIRD CAMPAIGN.

6. [Safety Division]

AN EMERGENCY DRILL WAS HELD ASSUMING RADIATION EXPOSURE ACCIDENT.

7. [Editorial Note]

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1. [Overview] by Takashi KOBAYASHI
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J-PARC OPEN HOUSE HELD ONLILNE ON NOV. 13th

   J-PARC open house was held online again in this year on Nov. 13th in order to prevent the spread of COVID infection. The videos were broadcasted through YouTube and niconico douga (Japanese localized streaming video service). The recorded videos can be watched on those sites.
https://j-parc.jp/c/information/2021/11/13000765.html (Only available in Japanese)

DETAILED DESIGN OF NEW ACCESS ROAD WILL BE MADE IN JFY2022

   In FY2021, J-PARC office made extensive effort to realize the new access road to the J-PARC area which has been desired for a long time by J-PARC user’s communities. We plan to make detailed design of the access road in JFY2022 to prepare for the construction when funded.

J-PARC INTERNATIONAL ADVISORY COMMITTEE (IAC) WILL BE HELD ON MARCH 3 AND 4 ONLINE

   Again this year, J-PARC IAC will be held online in Japanese night time. 

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2. [Accelerator Division] by Michikazu KINSHO
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STABLE OPERATION OF THE ACCELERATORS FROM OCTOBER TO DECEMBER

   A new operation run was started late in November after the summer shutdown. Accelerator studies at beam currents of 5 mA, 50 mA, and 60 mA were carried out at the linac.
   The studies were followed at the 3 GeV Rapid Cycling Synchrotron (RCS) with linac beam current of 50 mA for user operation and 60 mA for higher beam power.
   The main purposes of the studies were to startup the machine, reproduce the accelerator parameters, confirm the performance of some new components installed during the summer shutdown, new parameter survey for lower beam loss, etc. Beam study of linac and RCS has been performed until December 17th.
   The neutron production target of the MLF was replaced during the summer shutdown. Due to the delay of target related work, beam user operation was postponed to January 15th, from the original schedule of end of November.
   The beam power for user operation is scheduled at 700 kW as before the summer shutdown.
   The Main Ring (MR) has entered a long maintenance period for upgrade from July 1st. until next autumn.
   The work has been progressing smoothly in preparation for the beam study operation in June next year.

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3. [Particle and Nuclear Physics Division] by Toshiyuki TAKAHASHI and Kyoichiro OZAWA
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ACCURATE MEASUREMENT OF DIFFERENTIAL CROSS SECTIONS OF SIGMA^{-}-PROTON ELASTIC SCATTERING (by Koji MIWA)

   The study of the hyperon-nucleon (YN) interactions is important to understand the nucleon-nucleon and baryon-baryon interactions and to reveal the origin of the short-range repulsive core owing to the interactions between quarks. Also, the YN interactions have essential roles in a high-density matter, such as a neutron star. One of the best methods to investigate the YN interactions is a scattering experiment between hyperons and protons. However, our knowledge on the YN scatterings is very limited due to the low experimental statistics obtained before.
   The J-PARC hadron experimental facility would become a game changer thanks to the potential to deliver high-intensity secondary beams. The J-PARC E40 experiment was performed to measure differential cross sections of Sigma-proton scatterings at the K1.8 beam line in Feb. 2019.
   By handling the high-intensity pi- beam of 20M/spill using novel detectors with a fast time response, approximately 100 times more Sigma^{-} hyperons are used as a Sigma^{-} beam. The Sigma^{-}-proton scattering events were identified by the recoil proton and pi- from Sigma^{-} decay which were detected by a newly constructed so-called CATCH system. The measured differential cross sections show a clear forward peaking structure as predicted by theoretical models. The success of the Sigma^{-} proton scattering experiment is a major breakthrough in providing accurate data to establish realistic baryon interactions.
   This result was published recently in Phys. Rev. C 104, 045204 (2021).

IN THE T2K COLLABORATION MEETING, EXTENSIVE DISCUSSION WAS HELD ON PHYSICS OUTCOME AND UPGRADE PROGRAM CHALLENGES (by Yoshiaki FUJII)

   Neutrino experimental facility and the T2K collaboration continue working on the upgrade of neutrino beam line and near detectors. Progress and challenges we are facing under COVID circumstances were extensively discussed during the T2K collaboration meeting, which was held from 11/24 to 12/15 through video connection.
   While mechanical fabrication is going fairly well, several delays were identified on the delivery of electronics. Suspension of over-sea travel is another critical issue for assembling work at J-PARC.
   In addition to the T2K oscillation analysis, joint analysis of T2K beam data and SK atmospheric data, and T2K-NOvA joint analysis challenges were also discussed.
  At the conclusion of the meeting, the spokespersons strongly encouraged collaborators to patiently cooperate to overcome these difficulties to open the doors to the exciting physics. 

STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET) (by Satoshi 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 and detector construction work continues; construction of the cryostat for the pion capture solenoid magnet is close to the end. The coil assembly which was assembled in JFY 2020 will be installed into the cryostat in JFY2022. Excitation test of the capture solenoid is expected immediately after delivery and installation to the beam line.
   The COMET collaboration plans to carry out an engineering run, called COMET Phase-alpha within JFY 2022. In this operation, 8 GeV primary proton beam will be delivered to the COMET experiment hall for the first time. Studies of the primary proton beam such as measurements of the beam extinction factor and beam profile will be carried out along with backward pion production yield measurement and estimation of secondary beam particle contents ratio.
   The COMET collaboration discussed the status and plan toward starting beam operation in Phase-alpha and Phase-I in JFY 2022-2023 during CM35. The meeting ran fully online with participation of most collaborators in 9 different time zones.

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

   The E34 collaboration prepares for precision measurements of the muon anomalous magnetic moment and electric dipole moment.
   KEK continues to work on the engineering design of the relocation of the access road and buried facility infrastructure on the construction site. The design of the extension of the H-line for E34 installation was advanced. The collaboration worked on the commissioning of new experimental area with surface muon, the S2 experimental area where the demonstration of laser ionization of muonium is scheduled. Fabrication of a part of the cavities of the Inter-digital H-type Drift Tube Linac (IH-DTL) and Disk-And-Washer is in progress. A new laboratory for assembly of the silicon tracking detector has been set up at the KEK Tsukuba campus.
   Dr. Masashi Otani (KEK) was awarded the AAPPS C.N. Yang award 2021 for his development of the muon linac for realizing the muon acceleration for the E34.

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4. [Materials and Life Science Division] by Toshiya OTOMO
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THE MAINTENANCE WORKS DURING THE SUMMER OUTAGE HAVE BEEN CARRIED OUT CAREFULLY AND SUCCESSFULLY

1) Neutron Source
   In view of promoting the radiation work safety, a long enough maintenance period was secured to avoid parallel works to mitigate the risk of radiation release or contamination, which led to the late start of user operation from January 2022. On October 18th, specimens were cut out from the fore front wall of the used target vessel which was operated with 740 kW at maximum. The maximum damage depth on the specimens was less than 1 mm, which was a promising result for the stable beam operation with greater beam power. On November 1st, the used mercury target vessel was replaced with a new one which has an improved structure of the mercury flow channel. That is, the bubble generator was installed at a position closer to the beam window by 100 mm compared to the former one in order to increase the bubble number density near the beam window for promoting the pressure wave mitigation effect. There was also another maintenance work on the gas process system, which is a crucial device for the target replacement, to replace a vacuum pump, and it needed special care to suppress the release of radioactive materials. The remote handling test of the moderator/reflector assembly (MRA) was carried out for the first time since the beam operation of MLF started. Experiences from those works will be reflected in the improvement of the maintenance procedure and radiation safety.

PROPOSALS FOR 2022A PERIOD WERE RECEIVED

2) Neutron Instruments and Science
   The MLF 2022A call for general use proposals (short-term and one-year) was closed on November 8th. We have received 303 neutron proposals including 6 new user promotion proposals. All the proposals are now under review process whose results will be notified around next February 2022. The experimental periods are from the beginning of April 2022 to the end of June 2022 for short-term proposal (tentative) and from the beginning of April 2022 to the end of March 2023 for one-year proposal (tentative) respectively.
   The 5th Neutron and Muon School (NM-school) was held as KEK-IINAS (Inter-Institution Network for Accelerator Science) School from December 6th to 9th in an online style for both of lectures and practices. The practical training course was carried out using the in-situ pressure neutron diffraction, the inelastic neutron scattering, the single crystal neutron diffraction, the high intensity neutron total scattering, and the positive muon spin relaxation in MLF respectively. https://mlfinfo.jp/sp/school/5th-nms/index.html
   In December 2020, the arrangement for cooperation on research and development in the field of neutron scattering science between ANSTO (Australian Nuclear Science and Technology Organisation), J-PARC (KEK and JAEA) and CROSS (the registered institute for public beamlines), the AJ-MoU (ANSTO/J-PARC Memorandum of Understanding), has been extended. Recently, a series of online workshops on specific scientific scopes and R&D of devices on neutron scattering under the AJ-MoU was held.
   The recent scientific press releases at MLF were issued as follows:
(1)."Superconductivity-driven ferromagnetism and spin manipulation using vortices in the magnetic superconductor EuRbFe4As4"
https://doi.org/10.1073/pnas.2101101118
(2)."Fine-Structure Analysis of Perhydropolysilazane-Derived Nano Layers in Deep-Buried Condition Using Polarized Neutron Reflectometry"
https://doi.org/10.3390/polym12102180
(3)."Emergence of spin-orbit coupled ferromagnetic surface state derived from Zak phase in a nonmagnetic insulator FeSi"
https://doi.org/10.1126/sciadv.abj0498
(4)."Deep learning approach for an interface structure analysis with a large statistical noise in neutron reflectometry"
https://doi.org/10.1038/s41598-021-02085-6

A LONG SUMMER OF MAINTENANCE & CONSTRUCTION WORK FOLLOWS

3) Muon Science Facility (MUSE)
   This summer's maintenance is a six-month long project that started in mid-July. At the rotating target, the rotating feeder is being replaced as part of the maintenance. It is recommended to replace it every two years, considering the wear and tear on the bearings. This is the first time since the rotating target itself has been replaced, and the work was carried out under careful preparation. However, an abnormality in the motor torque was confirmed during the test operation after the work, and it was presumed to be caused by the misalignment of the joint connecting the target rotation shaft and the drive shaft on the vacuum side. The work to readjust the joint position was scheduled for mid-December.
   In the Experimental Hall No. 1, the cooling water piping and power cable laying work for the H-line has progressed and was almost completed by the end of November. Remaining works including the installation of control/monitoring systems for beamline components are being made with the aim of the first beam transport early next year. In addition, a major modification of the S-line is underway to install part of the power supply system for the kicker magnet outside the beamline shield to allow quick access for repair upon the failure of the power supply, which frequently occurs during beamtime. The stable operation of the kicker magnet is crucial for the simultaneous experiments in the S1 and S2 areas, which are scheduled to start in the next beamtime.
   Meanwhile, in this proposal round, MUSE received 50 muon proposals for the 2022A periods, and the review process for these proposals is now underway.

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5. [Nuclear Transmutation Division] by Toshinobu SASA
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CORROSION EXPERIMENT GOES TO THIRD CAMPAIGN 

   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 Nickel from steels and that drastically decreases the lifetime of the structural materials.
   There is a way to solve the issue by the technologies of controlling oxygen potential to suppress the dissolution of the elements in steel by flowing LBE which is studied worldwide. When oxygen potential is kept in appropriate range (around 10-7%), an oxide film formed on the steel and then, the direct contact of materials and flowing LBE are suppressed. Oxygen potential in LBE can be controlled by mixture of two carrier gases, oxygen-rich argon gas and hydrogen-rich argon gas. By controlling the flow amount of these two gases with inert pure argon carrier gas, the oxygen potential of the LBE can be managed. By applying this technology, automatic oxygen potential control systems are installed to our two large-scale LBE loops, “IMMORTAL E a mockup loop for LBE target, and “OLLOCHI E a corrosion test loop with flowing high-temperature LBE. 
   Since last fiscal year, the corrosion test campaign has started using OLLOCHI. The first campaign was successfully done last February and then, a second campaign was performed during last spring season. These two campaigns were performed under the same exact operation condition, 1 m/s of LBE flow speed at test section, 450 ºC to 350 ºC of temperature gradient, 10-6 % of oxygen concentration in LBE, and 2,000 operation hours. The purpose of these two campaigns was the functional test for corrosion test including the confirmation of reproducibility of the experimental conditions. The post examinations of the samples are underway to check the viability of the experiments using OLLOCHI.
   The third campaign has started in October, 2021 as a substantial corrosion experiment for LBE application to ADS. Three sample holders which stored 26 corrosion test specimens in one holder were prepared to perform the time dependent corrosion tests by changing exposure time from 2,000 hours, 5,000 hours, and 7,000 hours. Because the OLLOCHI has three test ports, the test can be performed in parallel using two of three ports by combination of 2,000 hours plus 5,000 hours exposure in one port and throughout 7,000 hours in another port. The test continues to next summer with short interruption for loop maintenance.

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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

   An emergency drill was held on Nov. 12, in cooperation with the Nuclear Science Research Institute of Japan Atomic Energy Agency. 
   It was assumed that the beam operation was started without evacuating a worker in the accelerator tunnel of Rapid Cycling Synchrotron and he was exposed to radiation. The drill included transportation and decontamination 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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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 
Jean-Michel POUTISSOU (English Editor): jmp at triumf.ca 
Keiko NEMOTO (Secretary): nemoto.keiko at jaea.go.jp
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