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2020.11.19

J-PARC Project Newsletter No.80, October 2020 dispatch

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     J-PARC Project Newsletter
                                                   No.80, October 2020
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]

   RESUMING OPERATION; OVERCOMING COVID-19 AT J-PARC.

2. [Accelerator Division]

   MAINTENANCE WORK DURING SUMMER SHUTDOWN.

3. [Particle and Nuclear Physics Division]

   NEW RESULTS FOR A KAON-NUCLEUS BOUND STATE: HINT OF A LAMBDA(1405)-NUCLEUS.
   NEW T2K ANALYSIS RESULTS AT SUMMER CONFERENCE AND COMMISSIONING OF
 NEW BEAM MONITOR PROTOTYPE.
   STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION. (COMET)
   STATUS OF THE MUON G-2/ ELECTRIC DIPOLE MOMENT. (EDM) (E34)
   PROGRAM ADVISORY COMMITTEE MEETING.

4. [Materials and Life Science Division]

  MAINTENANCE WORKS ARE GOING ON.
  PROPOSALS FOR 2020B + 2021A ROUND WERE RECEIVED.
  CONSTRUCTION AND MAINTENANCE WORKS IN PROGRESS WHILE COVID-19 WOES
  CONTINUE.

5. [Nuclear Transmutation Division]

  MEASUREMENT OF SPECTRAL INTENSITY OF NEUTRONS PRODUCED AT THE
  TARGET.

6. [Safety Division]

  J-PARC SAFETY DAY 2020.

7. [Editorial Note]

 

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1. [Overview] by Naohito SAITO
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  RESUMING OPERATION; OVERCOMING COVID-19 AT J-PARC

     We hope you all are doing well and staying healthy. In Japan,
the number of positive cases once peaked out around the beginning of
August, but started to increase gradually over the last month.
Therefore, we are maintaining the preventive measures against COVID-19
as described at our special homepage:
http://j-parc.jp/c/en/j-parc-covid/index.html. As the nature of the
virus is revealed by many researchers all over the world, we are
learning about more effective preventive measures at the office and
at the experimental hall. We trying to reflect those newly learned
measures onto our daily exercise.  For example, recognizing the
importance of ventilation and fresh air, all cabins at the Material
and Life Science Facility are now equipped with air purifiers.
     Resumption from the summer shutdown was only slightly affected
by the COVID-19, but we have regretfully announced the delay of the
user operation of Material and Life Science Experimental Facility
(MLF) by three weeks, from November 9 to December 1, due to more
careful execution of the target vessel replacing work. As a result,
the beamtime of this fiscal year will continue until the very end of
coming March. Our beamline scientists are communicating with the
users whose beamtime was assigned to affected period to minimize the
impact of the delays.
     While many maintenance works were carried out, we also held the
open house online for the first time due to the COVID-19 pandemic.
The online-open house included a live streaming from the experimental
areas, science talks, and special discussion session with the Mayor of
Tokai Village, Mr. Osamu YAMADA. The event was broadcast through
YouTube, and now archived at our homepage:
http://j-parc.jp/c/OPEN_HOUSE/2020/ .
     Mayor Yamada expressed his willingness to openly welcome all
users from domestic and overseas institutions to Tokai Village. He
reiterated the importance of open access to the J-PARC site. We have
agreed to work together to realize open access at the earliest occasion.
     Regarding the future of J-PARC, two major items of progress have
been made. One is the Roadmap of our funding agency, the Ministry of
Education, Culture, Sports, and Science and Technology (MEXT)
(https://www.mext.go.jp/b_menu/shingi/gijyutu/gijyutu4/toushin/1388523_00001.htm)
which was established to include our project as one of fifteen important
projects based on the Master Plan 2020 by Science Council of Japan.
The roadmap will be the basis of funding in the next decade, and
we are happy that the importance and the urgency of our project were
highly recognized by the MEXT. The other is the KEK roadmap, which is
undergoing revision in communication with relevant communities. The
interim report was just released worldwide for comments. See details at
https://kds.kek.jp/event/35643/. The roadmap widely covers wish lists
of relevant communities, and is the basis of Project Implementation
Plan (PIP) which will be the prioritized list of projects for future
funding request from KEK. Therefore, it is the important blueprint
of our future research programs. Comments are most welcome until
December 4th. 
     With the refreshed facilities after maintenance, continuously
improved infection prevention measures, and established future plans,
we would like to create more excitement together with users from all
over the world!

 

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2. [Accelerator Division] by Michikazu KINSHO
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  MAINTENANCE WORK DURING SUMMER SHUTDOWN

     Beam operation was suspended for maintenance during the summer
shutdown from July to October. Maintenance of the components and
study of new components were conducted in the accelerator facilities.
     The linac had been operated stably in these several months. But
one of the Separated-type Drift Tube Linac (SDTL) cavities had a
symptom of increasing the radio frequency reflection power in the
vicinity of the designed operation power. The reason was a dirty
surface of the cavity. So we cleaned it with dilute sulfuric acid
dipped cloths. During the inspection in the maintenance, we found a
failure for the klystron system: slight oil leaks for a capacitor
bank of klystron power supply. It was replaced with spare and we
confirmed that the other systems are healthy.
     The 3 GeV Rapid Cycling Synchrotron (RCS) also had been operated
stably before summer. Since beam power was increased, high residual
dose chronically exists in the RCS injection area by the highly
radio-activated vacuum chambers and magnetic cores due to beam
scattering by the 1st charge stripping foil. To protect maintenance
workers, we prepared a stand on which a backup shield can be installed
during maintenance work in this area.
     The Main Ring (MR) also had been operated stably before summer.
We have worked to achieve faster repetition and increased beam
intensity. Specially, we have tested a new power supply for main
magnets and installed two additional 2nd harmonic cavities in the beam line.
     The J-PARC accelerator facilities are scheduled to start beam
tuning at the linac on October 30. After the tuning and beam study of
the accelerators (linac and RCS), the user operation of the MLF is
expected to start in November, and MR beam tuning and beam study will
be started from December 10.

 

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3. [Particle and Nuclear Physics Division] by T. TAKAHASHI and K. OZAWA
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  NEW RESULTS FOR A KAON-NUCLEUS BOUND STATE: HINT OF A LAMBDA(1405)-NUCLEUS
(Y. ICHIKAWA)

     Kaonic nucleus is a bound state between anti-kaon and nucleus
and it attracts wide interest for study of interactions between kaon
and baryons.  An experiment performed at Hadron Experimental Facility
of J-PARC shows new results for study of kaonic nucleus.

     In the past, several experiments studied the simplest kaonic
nucleus, such as a K-pp system, using measurements of X-rays emitted
by kaonic atom. However, the depth of the potential is under
discussion, because both a "shallow" potential (-80 ~ -40 MeV) and a
"deep" (-200 ~ -150 MeV) potential can reproduce the systematic data
sample of the kaonic atom X-rays. Therefore, a new experimental
constraint without kaonic atom data is awaited.

     Recently, the inclusive missing-mass spectrum of K-p reactions
on a carbon target is measured by the J-PARC E05 experiment. In this
experiment, both momenta of incoming K- and outgoing protons are
measured accurately and the missing mass is reconstructed. The measured
spectrum is compared with a theoretical calculation by varying the
potential depth between anti-kaon and nucleus. The measured spectrum
shape is best reproduced with the potential depth of -80 MeV,
corresponding to a "shallow" potential. The measured spectrum is
difficult to reproduce with the "deep" potential. Moreover,
a significant event excess regarding the reproduced spectrum is
observed in the deeply bound region (~ 100 MeV). A possible
interpretation is a deeply bound state of a Y: -nucleus system,
where Y: means Lambda(1405) or Sigma(1385). This report will be
published as Progress of Theoretical and Experimental Physics.
(https://academic.oup.com/ptep/advance-article/doi/10.1093/ptep/ptaa139/5904281?guestAccessKey=c9e2316a-e795-4998-96f3-d1bda4bc3a42)

 

  NEW T2K ANALYSIS RESULTS AT SUMMER CONFERENCE AND COMMISSIONING OF
NEW BEAM MONITOR PROTOTYPE (by M. FRIEND, S. CAO and T. MATSUBARA)

     In the NEUTRINO 2020 conference, T2K released new oscillation
analysis results with about 30% more v-mode data, corresponding to
1.97x10^21 (neutrino beam mode) and 1.63x10^21 (antineutrino beam mode)
protons on target from the accelerator. Significant improvements were
made in the modeling of neutrino interactions and flux for the analysis.
A large range of values on the leptonic CP violating phase around +90 deg
were excluded at the 99.7% (3 sigma) confidence level, which is
consistent with previous results. Future upgrade programs including
higher beam power and improved near detectors were also presented.

     A new Beam Induced Fluorescence (BIF) monitor is under development
in the T2K primary beamline, where the proton beam profile will be
measured by detecting fluorescence light produced by proton interactions
with gas injected into the beam pipe. It allows us to carry out a
continuous and non-destructive beam profile measurement, which is not
accessible with the present beam profile monitors. A working prototype
was installed in the beamline in 2019, and BIF light was successfully
observed in the neutrino beamline for the first time in early 2020.
The beam profile measured by the prototype BIF monitor was relatively
consistent with that measured by neighboring monitors. Analysis of the
first BIF data is ongoing.

 

  Recent Publications

o First measurement of the charged current anti-muon neutrino double
differential cross section on a water target without pions in the final
state, K. Abe et al.
https://doi.org/10.1103/PhysRevD.97.012001

 

  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 sensitivity better
than 10^{-14} in Phase I.

     In the ICHEP 2020 conference H. Nishiguchi reported the status of
the COMET experiment. He summarized facility and detector
construction status along with schedule towards the start of the
experiment. He also explained the proton beam extinction factor study
at J-PARC, which is thought potentially to limit the experiment
sensitivity.

     Facility construction work continued in Summer after the B-Line
operation in the Hadron Experiment Facility completed in June.
Main work in the beam line construction is to complete air
sealing along the proton beam line for COMET (C-Line) with
strong support by the primary proton beam line group.
C-Line construction in the Hadron Experiment Hall will be
completed this year.

     The collaboration has been intensively working toward integrating
sub-detector components into a mu-e conversion search detector.
The Cylindrical Drift Chamber (CDC) and Cylindrical Trigger
Hodoscope (CTH) will be integrated and installed in a solenoid
magnet with 1 Tesla magnetic field. Detailed design of cabling
and piping as well as electronics cooling scheme is in progress.

     KEK held its open house on September 6th online where KEK COMET
members attended sessions and explained the physics of Lepton Flavor
Violation. An introductory video of the COMET facility has been
created for this purpose;
https://www.youtube.com/watch?v=Z-jiw_-gk0M&t=30s

 

  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.
A new beamline (H-line) is being constructed. Ground survey is in
progress for the area where a new experimental building is planned.
The collaboration received a new grant-in-aid funding for construction
of the detector system, field monitoring system, injection beamline,
and design and testing of accelerator cavities.

     Demonstration of laser ionization of muonium for the thermal
energy positive muon source is in preparation. The experimental setup
was reconfigured to fit to the upcoming experiment at J-PARC. A paper
on the study of muonium emission from laser-ablated silica
aerogel was accepted for publication in PTEP. Preparations for 1 MeV
acceleration of muons with RFQ and IH-DTL are in progress at the J-PARC
linac bldg. A design of coupling DAW (Disk And Washer) cavities for
middle range velocity has been made. A detail simulation on spin
dynamics of muon beam during acceleration is in progress. The
three-dimensional beam injection has been studied with a low energy
electron beam by KEK and Ibaraki University.
     M. A. Rehman (Sokendai) defended the Ph.D thesis on this research
in August. The silicon tracking detector is being assembled at
the KEK mechanical engineering center in collaboration with Kyushu
University. A paper on front-end electronics was published in IEEE TNS.

  PROGRAM ADVISORY COMMITTEE MEETING (by T. KOMATSUBARA)

     The 30th Program Advisory Committee (PAC) meeting was held,
for the first time as a video conference, on July 20-22. In the
committee, chaired by Dr. Rik Yoshida (Argonne National Laboratory),
both new and old members whose term began from April 2020 and
completed in March, respectively, participated jointly. Status of the
experiments was reported, and proposals and near-term machine
time allocation were discussed.
https://kds.kek.jp/indico/event/34935/

     PAC report will be available through the following web page.
http://j-parc.jp/researcher/Hadron/en/PAC_for_NuclPart_e.html
     The next PAC meeting will be held in January 2021.

 

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4. [Materials and Life Science Division] by Toshiya OTOMO
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  MAINTENANCE WORKS ARE GOING ON

1) Neutron Source
     On July 10, the used mercury target vessel, which was in
operation from 2016 to 2017, was transported from MLF to the storage
building, which is called RAM building where a total of 3 used target
vessels are stored now. To increase the storing capability of used
target vessels in RAM building, R&D for reduction of the volume of
used targets is on-going. The proton beam window #3 which was used for
3 years was replaced to #4. Since the proton beam window is a high
radioactive component, the replacement work was carried out with
special care to secure the radiation safety. On September 11, the
operation tests on the safety interlocks of MLF were carried out
successfully based on the periodical inspection that is conducted
once every 5 years by the Nuclear Safety Technology Center (NUSTEC).

 

 PROPOSALS FOR 2020B + 2021A ROUND WERE RECEIVED

2) Neutron Instruments and Science
     The proposal round for the period combined with 2020B + 2021A
was closed on July 15th. The largest ever number of 384 neutron
proposals has been recorded. All the proposals are now under the
review process whose results will be notified till the end of October.
     MLF was operated with 1MW proton beam power almost for 2 days at
the end of the last cycle. Some neutron instruments provided full
power of neutrons to user experiments, while some performed test
experiments such as high throughput data deduction, in situ
experiments and new type detector development, and so on.
     We are accelerating introduction of remote control and
automated measurement of neutron experiments with the aid of a
governmental grant, with adjusting to the "Corona era". We are going
to join a new government project organized by New Energy and
Industrial Technology Development Organization (NEDO) for the purpose
of promoting wide use of fuel battery.
     Outstanding scientific outcomes at MLF were issued with Press
Releases: 1) Research of transverse asymmetry of gamma rays from
neutron-induced compound state of 140La by T. Yamamoto and
co-workers, and 2) Neutron diffraction monitoring of ductile cast
iron under cyclic tension-compression by S. Harjo and co-workers.

 

  CONSTRUCTION AND MAINTENANCE WORKS IN PROGRESS WHILE COVID-19 WOES
CONTINUE

3) Muon Science Facility (MUSE)
     Since last March, MUSE experienced an unprecedented situation
of frequent rescheduling and temporal shutdown to cope with the
impact of COVID-19 that eventually led to the unscheduled shutdown of
the entire J-PARC due to the government emergency declaration and
associated regulations in mid-April. Fortunately, the operation
was resumed in mid-May in response to the partial mitigation of the
regulations. The proton beam power was then ramped up to 1 MW
(920 kW for MLF) towards the end of the beam cycle in June, providing
the first occasion for the renewed rotating muon production target to
be exposed to the full-power beam without interruption for 32 hours.
The target itself and surrounding devices were confirmed to respond
as designed, endorsing the future operation.
     In the MLF building, construction works for the new S2 area and
remaining part of H line have started in the summer maintenance
period.  The alignment of beamline magnets was completed for both H1
and S2 area, respectively, and installation works for various
supplies such as electricity, cooling water, and pressurized air are
underway. The regular maintenance is also in progress for the
rotating target and other beamline components in parallel with the
construction works.
     Meanwhile, in this proposal round, MUSE received record-many,
73 muon proposals for the 2020B + 2021A periods, where the call was
made for two periods together because of the delay due to COVID-19.
Although MUSE still faces an uneasy situation for scheduling experiments
in these rounds, the review process for these proposals is now underway.

 

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5. [Nuclear Transmutation Division] by Shin-ichiro MEIGO
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  MEASUREMENT OF SPECTRAL INTENSITY OF NEUTRONS PRODUCED AT THE TARGET
 
     Accelerator-driven transmutation system (ADS) using
a high-intensity proton accelerator has been proposed. For the
radiation safety of ADS, the yield of neutrons produced at the
target is essential, especially for the neutrons penetrating through
the proton beam duct with the inverse direction to the beam. To
validate the calculation code employed for the design of ADS and
spallation neutron source, such as Particle and Heavy Ion Transport
code System (PHITS), measurements of spectrum intensity of neutrons
produced from the target were carried out in J-PARC. The spectral
intensity of neutrons was observed by the detector placed upstream
of the beam direction of the mercury target of MLF using the
time-of-flight technique.
     Based on the present experiment, comparisons of calculations
were made. With the default new intra-nuclear cascade model of PHITS
(INCL4.6) coupled with the generalized evaporation model (GEM), the
calculation result reproduces the measured neutron yields fairly
well. In contrast, an apparent overestimation is observed for the former
default cascade model of Bertini coupled with GEM. This tendency is
consistent with the experimental results of neutron-induced reaction
rates obtained using the foils activation technique. Furthermore,
results of proton-induced neutron-production double-differential
cross-sections are found to be consistent with the present experimental
results. It was shown that INCL4.6/GEM is superior to Bertini/GEM in
terms of predicting 3-GeV proton-induced neutron production with the
inverse direction to the proton beam.

 

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

     The J-PARC Center had held "the J-PARC Safety Day" around May 23
on which the radioactive material leak incident occurred in 2013.
     However, due to concerns related to the novel coronavirus (COVID-19),
the Safety Day 2020 was postponed and held on September 9th by online
meeting.
     Following the introductory talk by the J-PARC director, some
good-practices related to safety and health were awarded. The main
talk entitled "Introduction to occupational behavior analysis" was
given by Dr. Rieko Hojo (National Institute of Occupational Safety
and Health, Japan). Further a newly-produced video on the radioactive
material leak incident in 2013 was presented.

 

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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@kek.jp
Kaoru SHIBATA: shibata.kaoru@ jaea.go.jp
Takatoshi MORISHITA: morishita.takatoshi@jaea.go.jp
Dick MISCHKE (English Editor): mischke@triumf.ca
Keiko NEMOTO (Secretary): nemoto.keiko@jaea.go.jp
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