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J-PARC Project Newsletter
No.70, April 2018
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]
NEW FISCAL YEAR STARTED TOWARDS NEW STAGE OF FACILITY OPERATION.
2. [Accelerator Division]
OPERATION STATUS OF THE ACCELERATORS.
ACCELERATOR TECHNICAL ADVISORY COMMITTEE (A-TAC) MEETING.
3. [Particle and Nuclear Physics Division]
SUCCESSFUL BEAM TIME WITH 50 KW BEAM POWER.
J-PARC NEUTRINO FACILITY CONTINUES TO ACCUMULATE T2K DATA IN ANTI-
NEUTRINO MODE.
STATUS OF THE MUON G-2/ ELECTRIC DIPOLE MOMENT (EDM) (E34).
STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET).
PROGRAMS OF ADVISORY COMMITTEE MEETINGS.
4. [Materials and Life Science Division]
STEADY NEUTRON PRODUCTION OPERATION CONTINUES WITH PROTON BEAM POWER
OF 400 KW.
SCHEDULED NEUTRON BEAM DELIVERY FOR 8-RUN CYCLES WAS ACHIEVED IN FY
2017.
GENERAL USER AND NEW USER PROMOTION NEUTRON PROPOSALS APPROVED FOR
THE 2018A PERIOD.
QUANTUM BEAM SCIENCE FESTA WAS HELD ON MARCH 2 TO 4.
COMING OF THE SEASON FOR MEETINGS.
5. [Nuclear Transmutation Division]
MATERIALIZATION OF ACCELERATOR-DRIVEN SYSTEM IN COLD LIQUID METAL
LOOP.
6. [Safety Division]
5TH SYMPOSIUM ON SAFETY IN ACCELERATOR FACILITIES.
THE APPLICATION FOR A LICENSE OF THE OPERATION WAS GRANTED.
7. [Editorial Note]
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1. [Overview] by Naohito SAITO
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NEW FISCAL YEAR STARTED TOWARDS NEW STAGE OF FACILITY OPERATION
We have just started the new Japanese fiscal year. I am now
reappointed as the director of J-PARC for three more years, which is
the end of the terms under the regulation. In the last three years, I
believe that we went through a phase change in the J-PARC operation
from the construction and initial production stage to a full
production stage as a research facility. The changes are not
complete yet, therefore the goal of the next three years is to
continue the phase change to accelerate the science production and
innovations.
The beam power at the Material and Life Science Facility (MLF)
is now brought up to 500 kW, which is 50% of the design. This
represents the third trial to operate the facility at 500 kW, the
previous two efforts were cut short due to a water leak in the
protection layer of the mercury target vessel. As was reported in the
previous newsletter, we went through a thorough investigation of the
cause and careful production of the new target, a.k.a. target#8, and
careful operation of that target at 300 kW in the beginning, then 400
kW from the beginning of the year. Through this process, we have
built our confidence to operate the target at 500 kW based on various
measurements and model calculations. We really hope that all MLF
users will be able to enjoy the higher power beam until the summer
shutdown. We plan to install an even more robust target, target#10,
to achieve higher beam power for more science production and
innovations with users.
The Main Ring is approaching 500 kW for the fast extraction
(FX), which is 67% of the design. The slow extraction (SX) also
achieved the 50 kW representing 50% of the expected maximal beam
power for SX. The accelerator team never stops improvements of the
beam power and quality even before the installation of the new power
supply. The new power supply is being prepared for further
exploitation of the high intensity frontiers in particle and nuclear
physics. While we are still waiting for the main funding, the
management is working together with the project team to minimize the
delay of the implementation of the power supply, especially
considering the power supply is an important prerequisite of world
leading physics program at the neutrino and hadron experimental
facilities.
All these facility improvements are for more science and
innovations to be produced with the users at J-PARC. We are looking
forward to working with more users for more excitements!
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2. [Accelerator Division] by Kazuo HASEGAWA
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OPERATION STATUS OF THE ACCELERATORS
After the New Year's holiday, the beam operation started on
January 7 as a new operation run: Run#78. The user program resumed
for the Materials and Life Science experimental facility (MLF) on
January 10. The beam power was increased to 400 kW, while it was 300
kW as of December.
A cooling water pump had a failure and was replaced on January
16. Therefore, the user program for the hadron experimental facility
(HD) was delayed from January 15 to 17. The beam power was 10 kW at
the start-up, but thanks to the beam tuning, the beam power achieved
50 kW, which was a long-desired power level. The other highlights in
this run were a successful slow extraction and delivery test at 8 GeV
for the Coherent Muon to Electron Transition (COMET) experiment. The
delivery to the HD ended on February 26 as scheduled.
The accelerators had a beam study time from March 1 to 7, and
then the beam delivery resumed to the MLF. The main ring operation
switched to the fast extraction mode and delivered beam to the
neutrino experimental facility from March 9 at the beam power of 470
kW.
The availability in the Japanese Fiscal Year 2017 (from April
2017 to March 2018) was high: about 93 percent for the MLF since we
had no serious troubles at the linear accelerator (linac), the Rapid
Cycling Synchrotron (RCS) and the MLF. The availability for the
Neutrino Experimental Facility (NU) and HD facility users was 89% and
66%, respectively. The cause of the low availability for the HD was
an electro-static septum trouble in April 2017.
ACCELERATOR TECHNICAL ADVISORY COMMITTEE (A-TAC) MEETING
The 17th A-TAC meeting was held at the J-PARC Research Building
from March 1 to 3. Eight committee members attended, and 15 reports
were presented such as operational status, commissioning results, and
performance upgrade. The committee deliberated the improvements,
directivity, etc., and gave recommendations.
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3. [Particle and Nuclear Physics Division] by T. TAKAHASHI,
T. NOMURA, K. OZAWA, T. ISHIDA, T. MIBE, S. MIHARA, AND
T. KOMATSUBARA
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SUCCESSFUL BEAM TIME WITH 50 KW BEAM POWER (by T. TAKAHASHI,
T. NOMURA, K. OZAWA)
Slow extraction (SX) beams from the Main Ring were delivered for
user operation from Jan. 13 to Feb. 26 in the beam time. We achieved
the beam power of 50 kW, and it was the important milestone in the
beam power development of the SX beam.
In the beam time, several experiments were conducted. The
E14/KOTO experiment continued taking physics data. KOTO accumulated
about 1e19 POT for physics data, which roughly doubled the total data
amount in 2017. For the operation at 50 kW beam, the experiment
implemented a new feature in the trigger scheme. To judge the
existence of associated extra hits in the detector, the information
of individual channels, each of which was energy calibrated, was
utilized in the new scheme. This scheme provided a sharper cut in
energy deposit distribution and thus enabled setting a tighter cut
condition and control of the trigger rate.
At the K1.8BR beamline, the E31 experiment was conducted to
accumulate three times larger statistics data than previously
obtained. The E31 experiment aims to study the structure of the
Lambda (1405) hyperon resonance using K- beam and a deuteron target.
The internal structure of the Lambda (1405) resonance is a long-
standing problem in hadron physics and the E31 experiment can provide
important information about a molecular-like structure of the Lambda
(1405) resonance.
At the K1.8 beamline, a new experiment E40 started to study
hyperon proton interactions by direct measurements of Sigma-hyperon
proton scatterings. In the experiment, Sigma hyperons are produced by
the (pi, K+) reaction on a liquid hydrogen target and are scattered
by protons in the same target. The released K+ is detected by the
rearranged KURAMA spectrometer, and a Sigma-hyperon proton scattering
is reconstructed with a newly installed detector. In this beam time,
the spectrometer and the detector were commissioned.
J-PARC NEUTRINO FACILITY CONTINUES TO ACCUMULATE T2K DATA IN ANTI-
NEUTRINO MODE (by T. ISHIDA)
The neutrino experimental facility at J-PARC has continued its
operation since last October for the T2K experiment. The beam is
stable with anti-neutrino mode at about 485 kW beam power.
Accumulated protons-on-target (POT) in last March has reached
1.5x10^20, which is to be added to the data already accumulated until
last December, 3.8x10^20.
We plan to continue the operation two more months towards the
end of May, in order to double the statistics of anti-neutrino mode
data until 2017 (7.6x10^20). Our primary interest is to see if
electron antineutrino "appears" as electron neutrino does in the
neutrino mode data, which was confirmed by T2K in 2013. With doubled
statistics, T2K has a sensitivity of 2.7 sigma on the electron
antineutrino appearance signal.
STATUS OF THE MUON G-2/ ELECTRIC DIPOLE MOMENT (EDM) (E34)
(by T. MIBE)
The E34 collaboration prepares for precision measurements of
muon anomalous magnetic moment and electric dipole moment.
An international workshop on hadronic vacuum polarization
contribution to muon g-2 was organized at KEK Tsukuba campus on Feb
12-14 (http://www-conf.kek.jp/muonHVPws/index.html). New theoretical
and experimental developments towards precise calculation of the muon
g-2 were presented. A white paper will be prepared from the outcomes
of this workshop and following ones.
A new muon beam profile monitor was tested at the Materials and
Life Science Experimental Facility (MLF). A small-scale prototype of
the positron tracking detector was used in the measurement of muonium
hyperfine splitting at MLF. A paper on magnetic design and method of
a superconducting magnet in a cylindrical volume with homogeneous
magnetic field was published.
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.
The COMET experiment requires a specially prepared proton beam
for producing the pulsed-muon beam as the beam timing information is
utilized to reduce the beam induced background well below the target
sensitivity; the proton beam of 8 GeV should have minimum leakage
from acceleration buckets to in-between pulses. The ratio of the
number of protons in-between two consecutive beam pulses to that in
a pulse, called extinction factor, should be less than 10^-10 to
achieve the target sensitivity of the experiment.
In January and February 2018, the first test of acceleration and
extraction of 8 GeV in this pulsed mode was executed by the
accelerator and beam transport groups, and the beam extinction
measurement was successfully carried out with help of the K1.8 group.
The preliminary result shows that the extinction level satisfies the
requirement by adopting a beam time window selection. It will further
continue the study to understand the details of the pulse time
structure.
PROGRAMS OF ADVISORY COMMITTEE MEETINGS (by T. KOMATSUBARA)
The 25th Program Advisory Committee (PAC) meeting was held at
Tokai on January 15-17. Status of the experiments was reported, and
proposals and near-term machine time allocation were discussed.
https://kds.kek.jp/indico/event/26624/
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 July 18-20, 2018.
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4. [Materials and Life Science Division] by Toshiji KANAYA
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STEADY NEUTRON PRODUCTION OPERATION CONTINUES WITH PROTON BEAM POWER
OF 400 KW
SCHEDULED NEUTRON BEAM DELIVERY FOR 8-RUN CYCLES WAS ACHIEVED IN FY
2017
1) Neutron Source
The proton beam power delivered to the neutron production
mercury target vessel has been increased up to 400 kW from January,
2018. The mercury target vessel, which is equipped with mechanically
coupled structure between the inner mercury vessel and outer water
shroud in the forward part has been running stably since last
October.
In March 20 2018, accumulated neutron beam delivery time reached
176 days (8-run-cycles), the operational goal of the fiscal year,
since April 2017. Resultant availability of the neutron source become
as high as 92 percent. Furthermore, fabrication of the spare target
vessel in the same structure as for current one was completed. The
current target vessel has a narrow channel mercury flow channel at
the front end of the target and equips a gas micro-bubbles generation
system as a measure of suppressing pitting damage induced by high
power pulsed proton beam injection.
GENERAL USER AND NEW USER PROMOTION NEUTRON PROPOSALS APPROVED FOR
THE 2018A PERIOD
QUANTUM BEAM SCIENCE FESTA WAS HELD ON MARCH 2 TO 4
2) Neutron Instruments and Science
From January 10, we resumed the last half of the user program
for the 2017B period, which continues until April 1. The 2018A user
program will start from April 4.
Proposals for 2018A were reviewed by the joint meeting between
Neutron Science Proposal Review Committee (NSPRC) and Proposal
Evaluation Committee (PEC) which was held on January 29. 174 general
user proposals for neutron instruments and five new user promotion
proposals for public beamlines were approved. The result was
authorized by the Materials and Life Science Experimental Facility
(MLF) Advisory Board and the Selection Committee in the joint meeting
on February 7. MLF also accepted one proprietary proposal. In this
period, the competition rate of general user proposals was 1.5.
Besides, urgent proposals are welcomed anytime.
Quantum Beam Science Festa, which is a conference for mainly
domestic users of J-PARC MLF and Institute of Materials Structure
Science (IMSS) of High Energy Accelerator Research Organization (KEK)
was held in Mito, Ibaraki Pref. on March 2 to 4 with 524
participants. In this Festa, MLF symposium was held on March 2 in
which MLF facility status, scientific results and developments were
reported. A meeting for MLF future planning, jointly organized by the
Japanese Society for Neutron Science and Society of Muon and Meson
Science of Japan, was also held on March 4, and a future planning for
the second target station of MLF was discussed.
COMING OF THE SEASON FOR MEETINGS
3) Muon Science Facility (MUSE)
The New Year started with a series of meetings for reviewing
2018A experimental proposals and the international advisory
committees over every level of J-PARC activities. Following the IMSS
Muon Program Advisory Committee for reviewing S-type proposals (long-
term projects), the Muon Science Proposal Review Committee was held
in the late January 2018 to review 27 general use proposals. The
committee approved 23 proposals for D1/2 and S1 instruments, while
three proposals that exclusively needed D1/2 instruments were set
priorities and put in the queue. The relatively sharp decline in the
number of submitted proposals in this round brought mild concern
among committee members to call for careful analysis, which was also
shared by the Muon Advisory Committee meeting held by order of
J-PARC director in late February.
In the meantime, the proton beam power ramped up to 400 kW while
keeping single bunch mode since January, and muon users enjoy the
world-highest flux for both positive and negative muons. It also
makes those comfortable who are working at the ultra-slow muon (USM)
commissioning on the U-line. While waiting for good news on the laser
ceramics for the UV laser final amplifier, they recently achieved 95
percent USM beam transport efficiency.
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5. [Nuclear Transmutation Division] by Toshinobu SASA
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MATERIALIZATION OF ACCELERATOR-DRIVEN SYSTEM IN COLD LIQUID METAL
LOOP
Lead-bismuth eutectic alloy (LBE), a typical liquid metal
coolant for fast reactor development, is adopted for the Accelerator-
driven System (ADS) proposed by JAEA to reduce the environmental
impact from minor actinides (MA). In the ADS, LBE acts both a
spallation target to produce spallation neutrons to drive the ADS and
a coolant of subcritical core to transmute MA by fission chain
reaction. The operation parameter for LBE-cooled ADS is specified to
maximize the MA transmutation efficiency and recovery of consumed
energy for ADS operation including high-current proton accelerator.
In the current design, maximum LBE temperature set to 450C and
100C of temperature difference are considered to transfer the
generated heat from the fission reaction of MAs loaded in subcritical
core. The spallation target, which will be installed in ADS Target
Test Facility (TEF-T), planned in J-PARC project, adopts the same
operation parameter to reproduce the operation environment of future
ADS in small spallation target and obtain irradiation data of
candidate structural materials for ADS components. The target is
bombarded by 250 kW proton beam from LINAC to irradiate various
materials, and deposited heat is taken out through the heat
exchanger. The secondary coolant of the heat exchanger is pressurized
water to miniaturize the heat exchanger mounted on movable trolley.
To gain the experience of entire LBE spallation target in
J-PARC, mockup loop IMMORTAL (Integrated Multi-functional MOckup for
TEF-T Real-scale TArget Loop) was built and has just started the
operation since the beginning of 2017. Operation tests progressed
steadily, by increasing flow amount of LBE, maximum operation
temperature up to 500C, and finally, set a temperature difference of
50C by running pressurized water heat exchanger. Each operation
test was succeeded in equable condition. Further tests reflecting
rated operation condition of future ADS will be performed in fiscal
year 2018.
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6. [Safety Division] by Yukihiro MIYAMOTO and Kotaro BESSHO
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5TH SYMPOSIUM ON SAFETY IN ACCELERATOR FACILITIES
After the accident at the Hadron Experimental Facility in 2013,
J-PARC Center holds a safety symposium every year in order to share
information on safety at accelerator facilities. The 5th Symposium on
Safety in Accelerator Facilities was held on January 25-26 at Ibaraki
Quantum Beam Research Center (IQBRC), and 124 participants exchanged
information on various safety issues at accelerator facilities. The
featured topics this time were radiation safety education and safety
in heavy load transportation works. Nine talks and eighteen posters
were presented by various institutions and universities in Japan. In
addition, two invited speakers from overseas gave talks on safety
training service at CERN by Mr. Christoph Balle and talks on ensuring
safety in the experiment using a tritium target by Mr. Albert
Manzlak, Jefferson Lab, USA. Domestic and international cooperation
between accelerator facilities is important for improving safety
status and continuing stable operations at accelerator facilities.
THE APPLICATION FOR A LICENSE OF THE OPERATION WAS GRANTED
The application for a license of the operation was granted by
the Nuclear Regulation Authority (NRA) on Feb. 26. The topics were
the increase of beam intensity for the Neutrino Experimental Facility
(NU) and the annex of the Materials and Life Science Experimental
Facility (MLF) for storing Radio-Activated Materials (RAM).
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7. [Editorial Note]
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Editorial Board:
Toshifumi TSUKAMOTO (Chair): toshifumi.tsukamoto@kek.jp
Kaoru SHIBATA: shibata.kaoru@ jaea.go.jp
Takashi ITO: itou.takashi@jaea.go.jp
Dick MISCHKE (English Editor): mischke@triumf.ca
Junko BEANBLOSSOM (Secretary): beanblossom.junko@jaea.go.jp
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