[Neutron] J-PARC Newsletter No. 77
shibata.kaoru
shibata.kaoru at jaea.go.jp
Wed Feb 5 12:08:47 CET 2020
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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 and 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. [Note]
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Past issues are available from the below link.
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
++++++++++++++++End of Letter++++++++++++++++++++++++++++++++++++++++
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