[Neutron] J-PARC Newsletter No. 76
shibata.kaoru
shibata.kaoru at jaea.go.jp
Fri Nov 8 11:25:03 CET 2019
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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
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Editorial Board:
Toshifumi TSUKAMOTO (Chair): toshifumi.tsukamoto at kek.jp Kaoru SHIBATA:
shibata.kaoru@ jaea.go.jp Taketoshi MORISHITA:
morishita.takatoshi at jaea.go.jp Dick MISCHKE (English Editor):
mischke at triumf.ca Tomoko KAWAMURA (Secretary): kawamura.tomoko at jaea.go.jp
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