J-PARC Project Newsletter No.76, October 2019 dispatch
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J-PARC Project Newsletter
No.76, October 2019
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]
RECOVERING FROM SUMMER MAINTENANCE; ENTERING THE
NEW PHASE OF OPERATION
2. [Accelerator Division]
MAINTENANCE AND RECOVERY WORK DURING SUMMER SHUTDOWN
3. [Particle and Nuclear Physics Division]
NEW EXPERIMENT IS BEING PREPARED AT THE HADRON FACILITY.
STERILE NEUTRINO SEARCH BY T2K EXPERIMENT.
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]
1 MW BEAM OPERATION WAS CARRIED OUT SUCCESSFULLY.
PROPOSALS FOR 2019B PERIOD WERE REVIEWED. ANNUAL MEETING
OF INDUSTRIAL APPLICATION AT J-PARC MLF WAS HELD.
MUON PRODUCTION TARGET REPLACED.
5. [Nuclear Transmutation Division]
DEVELOPMENT OF BEAM PROFILE MONITOR FOR ADS.
6. [Editorial Note]
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1. [Overview] by Naohito SAITO
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RECOVERING FROM SUMMER MAINTENANCE; ENTERING THE
NEW PHASE OF OPERATION
We are in the process to recover the facility from the summer maintenance.
During this summer shutdown, we were able to replace the beam-transfer
bending magnet, which malfunctioned in the spring beam time. In addition,
a new primary beamline and new target system are being prepared at the
Hadron Experimental Facility (HEF). The new primary beamline will be used
for the measurement of hadron mass modification in the nuclear medium
(E16), as well as muon to electron conversion experiment (COMET-phase1).
These two experiments represent a new phase of the experiments at HEF.
The new target system has a doubled cooling power, which bring us to a
world-highest beam-power era for slow extraction (SX). While the beam time
at the Main Ring was limited, we have been preparing the new power supply
(PS) for higher repetition rate for fast extraction (FX) and better stable
uniformity for SX. A partial test of the new PS was successfully done,
showing the expected stability. It has provided a reasonable level of confidence
to reach the design goal of 750 kW and more after the new PS implementation.
Together with the successful 1 MW operation for more than 10 hours at
Materials and Life Science Facility, which was reported in the last newsletter,
the J-PARC facility is clearly entering the new phase after 10 years of user
operation.
This important moment of transition of the facility to enter this new phase was
also witnessed by more than 600 participants at the ceremony held on 24th of
September, celebrating the 10th anniversary of J-PARC user operation. The
ceremony was also a part of the scientific symposium, J-PARC 2019. The
presentations and photo are available at the link below:
https://j-parc.jp/symposium/j-parc2019/
Now the accelerator commissioning is ongoing from the linac. We intend to
return the beam to users on schedule. We are all excited to restart the beam to
share more discoveries with users and society!
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2. [Accelerator Division] by Kazuo HASEGAWA
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MAINTENANCE AND RECOVERY WORK DURING SUMMER SHUTDOWN
Beam operation was suspended for maintenance during the summer
shutdown from July to September. Maintenance of the components and
some recovery work from failures 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, which
we cleaned using acetone dipped cloths. During the inspection in
the maintenance, we found several failures for the klystron systems: slight
water leaks for a 972 MHz klystron and insulator damages in an oil tank.
They were replaced with spares and we confirm that the other systems are
healthy.
The 3 GeV Rapid Cycling Synchrotron (RCS) also had been operated
stably before summer. But in March, we had damages in some of the
magnetic alloy (MA) cores in an accelerating cavity. We had operated with
a temporary measure, but we replaced these cores as a permanent measure
in this summer. The failure of the bending magnet coil in the beam transport
line from the RCS to the Main Ring (MR) stopped beam operation for two
months before summer. The important task for the MR is a recovery of the
magnet. The upper yoke was dismounted and the damaged coil was removed, then
a spare coil was mounted. We confirm that the electric property is as we
expected. We will connect to the power supply and have a test before beam
operation.
The J-PARC accelerator facilities are scheduled to start beam tuning at the
linac on October 22. After the tuning and study of the accelerators, the
user operation is expected to start in November.
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3. [Particle and Nuclear Physics Division] by K.OZAWA,
M.HARTZ, T.ISHIDA, S.MIHARA, T.MIBE, T.KOMATSUBARA
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NEW EXPERIMENT IS BEING PREPARED AT THE HADRON
FACILITY. (K. OZAWA)
A new experiment and a new beam line are being prepared at the Hadron
Experimental Facility. The experiment aims to study hadron properties in the
nucleus and its relation to QCD properties of nuclei. The experiment
measures mass spectra of vector mesons in a nucleus, since the vector
mesons can be considered as excitations of “QCD vacuum” and its mass
spectra have fruitful information for “QCD medium” at a finite
density region.
The vector mesons are generated using proton-nucleus reactions.
Then, some fraction of vector mesons decay inside the nucleus and have
information about the nuclear medium. Decays of vector mesons are detected
through electron-positron decays, since hadrons from the decays can
be modified by the nucleus and can’t carry direct information of the
nuclear medium. The branching ratio of electron-positron decays are very
small and a very thin target must be used to avoid interactions between
decay electrons and the target. Thus, a high intensity beam and a
large acceptance spectrometer must be prepared for the experiment.
Currently, a new proton beam line is constructed to provide a high
intensity beam. All magnets of the new beam line are placed at their proper
places and tested. In addition, constructions of a new spectrometer is
underway. The spectrometer magnet is already set up and its magnetic
field has been measured. Lead Glass calorimeters for electron
identification are already installed. Remaining detectors are almost
produced and will be installed by the end of this year.
We will start the new experiment using the new beam line in
February 2020.
STERILE NEUTRINO SEARCH BY T2K EXPERIMENT. (by M. HARTZ, T. ISHIDA)
During summer maintenance, a bending magnet which caused unexpected
interruption of the Main Ring operation in last April was successfully replaced
by a new one. The fast extraction mode operation for T2K experiment will
be resumed from early November.
Recent publication: “Search for light sterile neutrinos with the T2K far
detector Super-Kamiokande at a baseline of 295 km”
Phys. Rev. D 99, 071103 (2019), DOI: 10.1103/PhysRevD.99.071103
T2K usually publishes neutrino oscillation measurements that assume
oscillations in the 3-neutrino mixing paradigm. However, it is possible that
additional “sterile” neutrinos exist that can only be detected through neutrino
mixing or oscillations. If these sterile neutrinos exist, T2K may observe
unexpected behavior in neutrino events at the Super-Kamiokande detector,
such as unexpected deficits in the total 3-flavor neutrino flux detected through
neutral current interactions, or unexpected distortions to the measured spectra
of muon-neutrinos and electron-neutrinos detected through charged current
interactions. In this paper, T2K finds no evidence for sterile neutrinos and
places limits on the parameters governing the mixing with hypothetical sterile
neutrinos. T2K places the strongest limit on the sterile mixing amplitude for
oscillation frequencies that are nearly degenerate with the standard 3-neutrino
oscillations observed in T2K.
“Search for neutral-current induced single photon production at the ND280
near detector in T2K” J. Phys. G: Nucl. Part. Phys. 46 (2019) 08LT01,
DOI: 10.1088/1361-6471/ab227d
T2K searches for neutrino oscillations by detected electron (anti)neutrino
events that produce a high energy electron or positron in the Super-K detector.
In Cherenkov detectors such as Super-K, neutral current neutrino-nucleus
interactions where a single visible high energy gamma ray is produced can
fake an electron or positron signal. T2K uses the precision tracking capabilities
of its ND280 near detector to search for this type of neutral current interaction
with a high energy gamma ray. T2K does not yet observe a statistically
significant signal for this interaction mode, but is able to place the first limits
on the interaction process for neutrino energies below 1 GeV, the energy range
that is most important for T2K.
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.
Construction of the COMET facility along with detector R&D is in progress.
Beamline elements are installed at the primary proton beam branching section
of the COMET beam line from the B-line. Winding of the last coil in the capture
solenoid will be completed within this fiscal year. The CDC, main detector of
COMET phase I physics measurement is tested with cosmic-ray muons with
full setup of electronics. The 1st station of the straw-tube tracker used in
beamline study is started. Intensive studies of radiation tolerance of detector
components are carried out at neutron and gamma-ray irradiation facilities.
Recently LYSO crystal and a new generation MPPC were newly investigated.
Qualification of the data is in progress. At the J-PARC symposium held in
Sep. 24-26, a status report of the COMET experiment was given along with poster
presentations describing the status of the experiment preparation.
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. There is a
theory initiative to improve the standard model calculation for g-2 of the
muon. They had a workshop at the University of Washington, Seattle in Sep.
9-13 to prepare for a white paper on the improved theoretical
calculation before the end of year. This number will be compared with the
ongoing experiment at Fermilab as well as the forthcoming E34. Following
an approval on stage 2 status for the experiment, the experiment works
with KEK for funding request. A task force to discuss resolutions on
extending the H-line area summarized the list of requirements and constraints
to be considered in the construction. A collaboration meeting on cross
calibration of magnetic field probes between E34 and Fermilab g-2 teams
was held in Sep. 2-4 at J-PARC, where results of the data analysis on cross
calibration were actively discussed.
PROGRAM ADVISORY COMMITTEE MEETING (by T. KOMATSUBARA)
The 28th Program Advisory Committee (PAC) meeting was held at
Tokai on July 16-18. To the committee, chaired by Dr. Rik Yoshida
(Jefferson Lab) since April 2018, Prof. Kam-Biu Luk (U.C. Berkeley)
joined as a new member from this meeting. Status of the experiments was
reported, and proposals and near-term machine time allocation were discussed.
https://kds.kek.jp/indico/event/31728/
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 on January 16-18, 2020.
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4. [Materials and Life Science Division] by Toshiji KANAYA
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1 MW BEAM OPERATION WAS CARRIED OUT SUCCESSFULLY.
1) Neutron Source
Stable and long-term beam operation for user program of more than 500kW
was achieved with high average availability of 95.8% since April 1 until July 3
in 2019. After the user program was ended on July 3, 1 MW beam operation was
carried out successfully with the duration time of 10.5 hours from 11:30 to 22:00
and the excellent availability of 98%. Due to the long duration time, facility data
of steady state under high power beam condition could be obtained for the first
time.
PROPOSALS FOR 2019B PERIOD WERE REVIEWED.
ANNUAL MEETING OF INDUSTRIAL APPLICATION AT J-PARC MLF WAS HELD.
2) Neutron Instruments and Science
The general and the new user promotion proposals for the 2019B period and long
term proposals were reviewed by the Neutron Science Proposal Review Committee
on August 26th. The total number of submitted neutron proposals was 385
(the general proposals: 372, the new users proposals: 7, long term proposals
from 2019B: 6). The number of proposals was the largest ever. Finally, 175 general
proposals, 7 new user promotion proposals, and 4 long term proposals were
approved by the MLF Advisory Board on September 5th. We will start the call for
proposals for the 2020A period from October 17th to November 7th. From the
next round, we will accept one-year-term proposals for BL11 (PLANET).
Annual meeting of industrial application at J-PARC MLF was held on July 18th and
19th at Akihabara Convention Hall. Total number of attendees was 282. According
to the theme of the meeting, “Collaborative Creation of Innovation”, three keynote
talks and oral presentations of collaborative research between industry and the
instrument group, which were carried out on four beamlines were held, as well as
a poster session and consultation of neutron beam usage for industrial purpose.
We held a J-PARC Workshop entitled “CSNS-J-PARC Collaboration Workshop on
Neutron Instrumentation”. From CSNS side, vice directors Prof. F. Wang,
Prof. T. Liang and eight instrumental scientists visited J-PARC. We have exchanged
the information of current status of each facility including neutron instruments
and have discussed possible future collaboration in neutron instrumentation.
MUON PRODUCTION TARGET REPLACED.
3) Muon Science Facility (MUSE)
Since the resumption of beam operation in November 2018, the soundness
of the muon rotation target was in limbo due to the potential damage of a
flexible joint for transferring motor rotation to the graphite disk target
(see Newsletter #73, 2018). Fortunately, the target served without trouble for
eight months, making those measures for potential hazards expected in case of
suspended target rotation almost useless. The target operation was then
continued for testing with 1 MW proton beam over a block of beam time for
10.5 hours towards the end of the cycle. The various physical parameters such
as target temperature and motor torque behaved nearly exactly as predicted
during the operation, and the muon-target team was convinced that the system
was ready to go for long-term 1 MW operation. Meanwhile, the team decided
to replace the current target with a brand-new copy after an unsuccessful attempt
to replace the suspected joint. This also served as the first occasion for the team
to replace the whole rotating muon target system after years of high-power
operation, where utmost precaution was taken to minimize radiation hazards
including that by tritium accumulated in the target system.
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5. [Nuclear Transmutation Division] by Shin-ichiro MEIGO
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DEVELOPMENT OF BEAM PROFILE MONITOR FOR ADS
Accelerator-driven transmutation system (ADS) using a high-intensity proton
accelerator such as with 30 MW beam power has been proposed. For steady
beam operation of the ADS, continuous diagnostic of the beam introduced to
the target by the profile monitor is essential. Therefore, a new profile monitor
has been developed using a luminescent material placed at the target. The
applicability for a beam monitoring system was examined at the cyclotron
facility at Takasaki Ion Accelerators for Advanced Radiation Application (TIARA).
In the experiment, the luminescent sample consisted of alumina doped 0.5% of
chromium (Cr) was utilized. In order to accelerate damage to the sample, the
150-MeV argon beam was irradiated on the sample to provide about 1 million times
dose for the proton. The beam profile was successfully obtained by the
radiation-hardened optical fiberscope system. In order to observe the degradation
of luminescence efficiency, a spectrometer was utilized. The spectrum of
luminescence had a prominent peak at 694 nm with several unresolved shoulder
peaks. After a few minutes of irradiation, the intensity decreased slowly and
steadily. The intensity of the unresolved peak in short-wavelength decreased less
than the intensity at the peak. By observing the shorter wavelength with optical
filter cutting out a long wavelength, the influence of degradation may be mitigated.
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6. [Editorial Note]
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Information on the project can be also obtained at the web site:
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
Taketoshi MORISHITA: morishita.takatoshi@jaea.go.jp
Dick MISCHKE (English Editor): mischke@triumf.ca
Tomoko KAWAMURA (Secretary): kawamura.tomoko@jaea.go.jp
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