J-PARC Project Newsletter No.77, January 2020 dispatch
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J-PARC Project Newsletter
No.77, January 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]
MORE POWER TO THE USERS AND TO SOCIETY.
2. [Accelerator Division]
STABLE OPERATION OF THE ACCELERATORS FROM OCTOBER TO DECEMBER.
3. [Particle and Nuclear Physics Division]
INSTALLATION OF A NEW PRODUCTION TARGET FOR SECONDARY
PARTICLES AT THE HADRON EXPERIMENTAL FACILITY.
RESTART OF THE NEUTRINO BEAM OPERATION FOR T2K.
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 REPLACEMENT OF THE MERCURY TARGET VESSEL WAS
CARRIED OUT.
THE START OF BEAM OPERATION WAS DELAYED FOR ONE MONTH
DUE TO THE FUNCTIONAL PROBLEM OF THE GAS PROCESS SYSTEM.
THE COLLABORATION MEETING WITH SNS FOR R&D OF SPALLATION
NEUTRON SOURCE DYSTEM WAS HELD.
THE 4TH NEUTRON AND MUON SCHOOL AND MIRAI PHD SCHOOL
2019 WAS HELD.
260 NEUTRON GENERAL PROPOSALS HAVE BEEN RECEIVED FOR
THE 2020A PERIOD.
THE MUON ROTATING TARGET WAS REPLACED.
40 MUON GENERAL PROPOSALS HAVE BEEN RECEIVED FOR THE
2020A PERIOD.
5. [Nuclear Transmutation Division]
LAUNCHING OPERATION OF CORROSION EXPERIMENT LOOP.
6. [Safety Division]
FY2019 J-PARC SAFETY AUDIT.
7. [Note]
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1. [Overview] by Naohito SAITO
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MORE POWER TO THE USERS AND TO SOCIETY.
This is the first newsletter in the year 2020.
As reported in the following sections, our facility has fully
recovered from the summer shutdown last year, and continued the operation
until the end of the year. Now we have restarted the facilities after the
end-of-year and new-year holidays, and all facilities are running stably.
Among many improvements in the facility operation, the Main Ring (MR)
is now operated beyond 500 kW for the first time for its user operation.
It is two thirds of the design power. Our plan has been and still is to
achieve
the design power of 750 kW by shortening the repetition time in the
Fast Extraction (FX) mode from 2.48 seconds to 1.32 seconds, which implies
the beam power should be around 400 kW before the new power supply (PS)
would be installed. The user operation at 500 kW is the result of
accelerator physicists' efforts in creative and persistent ways. We are
really
looking forward to a new era of MR operation with the new PS to come in two
years.
Along the line of the MR power upgrade, the budget for facility upgrades
towards the Hyper-Kamiokande project is now included in the Budget Bill of
JFY2021 supplemental budget together with the budget for the new PS. It
will definitely boost the particle and nuclear physics at J-PARC. In the
Hadron
Experimental Facility, a new beamline, referred to as B-line, to utilize
the primary proton beam will start to operate for the experiment to study
the
mass modification in the nuclear medium. The beam line is to be shared
with the COMET experiment, which will run in a few years in a search for
muon to electron conversion. We hope to provide new scientific results
out of these new initiatives in coming years to explore the fundamentals
of nature further.
In addition, both muon target holder and neutron production target
vessels
have been renewed. The new muon target is expected to last for another
decade even with 1 MW operation at the Material and Life Science
Experimental Facility (MLF). The new neutron target vessel is designed and
built under a completely new concept, which we believe will lead us to
1 MW operation soon at the MLF. We have been producing press-release
level outputs at an average rate of more than one per month. Some of them
are relevant to a possible solution to the world-wide energy problems. We
definitely hope to contribute to mitigate the climate crisis.
Having all
these
advances, we are definitely entering to a new phase of facility operation,
where the operation with even more stability and higher power can be
achieved for more science production at all facilities.
Hi-power beams for the next stage of our life!
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2. [Accelerator Division] by Kazuo HASEGAWA
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STABLE OPERATION OF THE ACCELERATORS FROM OCTOBER TO DECEMBER.
A new operation run was started late in October after the summer
shutdown. Accelerator studies at the beam current of 5 mA and
50 mA were carried out at the linac. The studies were followed at the
3 GeV Rapid Cycling Synchrotron (RCS) and Main Ring synchrotron (MR)
at the linac beam current of 50 mA for user operation. 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.
On November 4, the beam delivery to the neutrino experimental
facility (NU) was resumed at the beam power of 400 kW. After the fine
tuning of the MR, we delivered beam at around 490 kW, which was the
similar level as the previous operation.
The neutron production target of the Materials and Life Science
Experimental Facility (MLF) was replaced during the summer shutdown.
Due to the delay of target related work, beam tuning and user operation
was postponed to December 6 and 12, respectively, from the original
schedule of early November. The beam power for user operation was
500 kW as before the summer shutdown. The user operation for the NU
and the MLF ended in the morning of December 19 followed by the five
days of accelerator study before the year-end shutdown.
After the shutdown, we will start linac tuning on January 9 followed
by the RCS and MR tuning. The user program of the MLF and the NU will
start on January 14.
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3. [Particle and Nuclear Physics Division] by H.WATANABE,
H.TAKAHASHI,
S.SAWADA, T. ISHIDA, S. MIHARA, T. MIBE
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INSTALLATION OF A NEW PRODUCTION TARGET FOR SECONDARY
PARTICLES AT THE HADRON EXPERIMENTAL FACILITY.
(by H. WATANABE, H. TAKAHASHI, S. SAWADA)
A new production target for secondary particles was installed
in November, 2019 to receive higher power beam at the Hadron
Experimental Facility. The previous target had been in operation
since April, 2015 without any problems. The beam power was gradually
increased and reached 51 kW, which was close to the design maximum
power of the previous target. To receive more intense proton beam,
a new target was developed. The new target is made of gold and is
indirectly cooled by water through a copper block.
Although the
cooling structure is the same as that of the previous target, the
cooling efficiency is improved by doubling the copper cooling block.
The newly designed target is capable of receiving the primary-proton
beam up to 95 kW for a 5.2-seconds repetition cycle.
The replacement procedure was carefully planned, and tested using
a mockup of a target chamber and the surrounding shielding structure.
The procedure was also examined with substantial consultations and
discussions with the Radiation-Safety section. The replacement work
was carried out cautiously according to the procedure, and successfully
completed. After the installation, the whole target system including
the temperature monitors, the cooling-water lines and chamber
airtightness was checked and works well.
Beam operation with the new target is scheduled from February,
2020. In the first period of the beam time, the performance of the new
target such as the cooling efficiency will be measured.
RESTART OF THE NEUTRINO BEAM OPERATION FOR T2K. (by T. ISHIDA)
On November 5th, the neutrino beam-line resumed its operation,
being awaited by the T2K collaboration for more than 1 year. It is in
neutrino mode, and beam power reached to 496kW.
At the near detector hall, a new detector system "Wagasci", has
started its data taking. It aims a detailed measurement on
neutrino-nucleus (water and plastic scintillator) interactions at
different neutrino energy from those at the existing near detector
system, ND280. The system has a muon spectrometer, Baby MIND,
constructed as a CERN neutrino platform project NP05. By comparing to
the measurement by ND280, the Wagasci measurement will provide
better understanding of the neutrino-nucleus interaction, which
is now the largest source of systematic error for the T2K oscillation
measurement. Another experiment, observing neutrino-nucleus
interaction by nuclear emulsion (NINJA) has also started its operation.
On December 13, the budget request for the Hyper-Kamiokande project
was approved by the Japanese Cabinet, as the supplementary
budget for FY2019. It also covers upgrade of the beam-line and
construction of a new near detector system. Every effort should be
made to realize these upgrades and construction in a timely manner.
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. The line is closed now
for providing the 1st beam through the B-line to E16 which uses the
primary proton beam for a nuclear physics experiment. Winding of the
last coil in the capture solenoid is underway to be completed within
this fiscal year. Significant progress has been made in the design work
of the tungsten alloy shield installed inside the capture solenoid for
protecting the super-conducting coils from radiation. Further detailed
investigation of the pion production target is initiated by involving
a new member with knowledge and experience of the material used in
high radiation environment. After the full setup test of the CDC, main
detector of COMET phase I physics measurement, optimization to achieve
the best performance of the detector is in progress. Construction of
the 1st station of the straw-tube tracker used in beamline study is
ongoing in good shape. The collaboration plans to have a collaboration
meeting at IIT-Bombay in India in February; participants from
the local area are expected to join the open session at the meeting
for the purpose of promoting the COMET experiment and J-PARC facility.
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. Following
approval of stage 2 status for the experiment, the experiment works
with KEK for funding request and engineering design for the construction.
The 19th collaboration meeting was held in Dec. 2-5 at J-PARC where
about 50 collaborators actively discussed progress and future plans.
Demonstration of laser ionization of muonium for the thermal energy
positive muon source is in preparation. Currently, a test setup was
constructed in KEK Tsukuba campus to ionize hydrogen atoms.
Preparations for 1 MeV acceleration of muon with RFQ and IH-DTL
are in progress at J-PARC linac bldg. The three-dimensional beam
injection has been studied with low-energy electron beam by KEK and
Ibaraki university.
The simulations confirmed the measured beam distributions.
The silicon tracking detector is being assembled at KEK mechanical
engineering center in collaboration with Kyushu University. A test
of magnet shimming and NMR probes has been carried out by the
J-PARC cryogenic group.
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4. [Materials and Life Science Division] by Toshiji KANAYA
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THE REPLACEMENT OF THE MERCURY TARGET VESSEL WAS CARRIED OUT.
THE START OF BEAM OPERATION WAS DELAYED FOR ONE MONTH DUE TO
THE FUNCTIONAL PROBLEM OF THE GAS PROCESS SYSTEM.
THE COLLABORATION MEETING WITH SNS FOR R&D OF SPALLATION
NEUTRON SOURCE DYSTEM WAS HELD.
1) Neutron Source
On October 8th, the replacement of the mercury target vessel was
carried out. The structure of the new mercury target vessel differs
significantly from the former ones in that the inner mercury vessel is
slotted
in the outer water shroud which is a water cooled vessel, and is fixed
together only at their rear end, while, in the former ones, the mercury
vessel and the water shroud were jointed with many ribs as a monolithic
structure. The new structure is expected to reduce thermal stress
generated by the difference of thermal expansion between those two
vessels. After that, due to the functional problem of the gas process
system which is a crucial device for the target replacement work, the
start of beam operation was delayed for one month, and finally the
neutron production for users began on December 12th with the beam
power of 500 kW. Before the user program started, the target beam
study was carried out. The temperature of the mercury target and sound
amplitude generated by the proton beam injection into the target were
compared with the former ones to check the structural soundness of
the new target vessel. The beam operation continued successfully an
user program ended on December 19th.
The collaboration meeting with SNS for R&D of spallation neutron
source system was held from December 10th to 13th. Five persons
came to J-PARC from SNS and had fruitful discussions on many aspects
of the target system.
THE 4TH NEUTRON AND MUON SCHOOL AND MIRAI PHD SCHOOL 2019
WAS HELD.
260 NEUTRON GENERAL PROPOSALS HAVE BEEN RECEIVED FOR THE
2020A PERIOD.
2) Neutron Instruments and Science
The user program after the summer shutdown was resumed from
December 12th. Due to the functional problem of the gas process
system, both of parts of 2019A and 2019B periods beam time were
cancelled. Compensation will be done by additional operation time in
March 2020 and in part of the 2020A period.
The 4th Neutron and Muon School 2019 was held as a joint school
with MIRAI PhD School from October 28th to November 2nd. Forty one young
researchers and graduate students from China, India, Korea, Sweden,
Russia, Thailand, Malaysia, Nepal, Spain, Hungary, and the USA, as well as
Japan, participated in the school. From the neutron groups and the muon
groups, 11 neutron instruments and 2 muon spectrometers contributed
to hands-on experiments, respectively.
The call for General use proposals and New User Promotion proposals for
the 2020A period was closed on November 7th and we received 260 neutron
proposals. Those proposals will be sent to the Neutron Science Proposal
Review Committee / the Proposal Evaluation Committee for reviewing process.
Final results will be sent to users in February.
THE MUON ROTATING TARGET WAS REPLACED.
40 MUON GENERAL PROPOSALS HAVE BEEN RECEIVED
FOR THE 2020A PERIOD.
3) Muon Science Facility (MUSE)
As reported a year ago, the potential damage of a flexible joint
within the muon rotating target system was suspected during the
summer maintenance in FY2018. After careful assessment of the
risk expected in case of joint breakdown, a multitude of safety
measures were imposed to allow for restricted operation of the target
until the next summer shutdown. Fortunately, the target served for
muon production without trouble for ca. seven months, and it was
finally replaced with a brand-new spare in the last summer shutdown.
This was the first occasion for the muon target team to replace the
whole system after high proton power operation, and utmost care was
taken to minimize the risk of radiation hazard during the replacement
work. Now the new target seems ready to be exposed to 1 MW proton
beam in the years to come. In the meantime, the cabling work for H-line
electricity made steady progress during the summer shutdown, coming
to the stage of installing a power panel in the MLF No.1 hall. The
scaffolding around the main carry-in door (where power cables pass
through) was removed after the completion of cabling work from the
new power substation to the interior of MLF. Those planning
experiments on the H-line are hoping to see the electricity turned on
sometime next year.
Muon Science Facility Call for General use proposals for the 2020A
period was closed on November 7th and we received 40 muon proposals.
Those proposals will be sent to the Muon Science Proposal Review
Committee for reviewing process. Final results will be sent to users in
February.
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5. [Nuclear Transmutation Division] by Toshinobu SASA
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LAUNCHING OPERATION OF CORROSION EXPERIMENT LOOP.
Accelerator-driven system designed by JAEA applies the lead-bismuth
eutectic alloy (LBE) for spallation target and reactor coolant. The issue
for
LBE is the compatibility with reactor materials. LBE has a characteristic to
dissolve out Nickel from steels, and it drastically decreases the lifetime
of
the materials in LBE. As an optimum solution, technologies to control
oxygen potential to suppress the dissolution of the steel by flowing LBE
is studied worldwide. When oxygen potential kept in an appropriate range
(around 10-7 %), an oxide film is formed on the steel and then, the direct
contact of materials and flowing LBE is suppressed. Oxygen potential in
LBE can be controlled by a mixture of the 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 managed. During this fiscal year, automatic oxygen potential
control systems were installed to our two large-scale LBE loops, "IMMORTAL",
a mockup loop for LBE target, and "OLLOCHI", a corrosion test loop.
Especially for the OLLOCHI, the oxygen potential during corrosion tests was
specifically important during the thousands hours of continuous operation.
The performance of oxygen potential control will be tested and then, the
loop
is ready to collect the corrosion test data in various experimental
conditions.
These technologies together with precise oxygen potential measurement
technique are all applicable for future accelerator-driven system
development as a key elemental technologies.
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6. [Safety Division] by Kotaro BESSHO and Yoshihiro NAKANE
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The FY2019 J-PARC safety audit was conducted by two auditors on December
16. They reviewed the points: 1) Management of work safety, 2) Promotion of
safety culture, and 3) Work management for target vessel replacement at the
MLF facility. Inspection of some works proceeding in the Hadron Experimental
Facility was also carried out. The auditors gave us valuable suggestions for
future safety efforts in J-PARC.
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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
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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