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J-PARC Project Newsletter
No.58, April 2015
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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EDITORIAL NOTE-------------------------------------------------------
In the process of editing this newsletter, we have received two
more important news on the operation of the Materials and Life Science
Experimental Facility with 500 kW from April 14 and resumption of the
operation at the Hadron Experimental Facility from April 24. More
details will be reported in a next special issue of J-PARC newsletter.
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HEADLINES AND CONTENTS
1. [Overview]
ACCELERATION OF A PROTON BEAM PULSE EQUIVALENT TO 1-MW WAS
SUCCESSFULLY DEMONSTRATED.
THE HADRON EXPERIMENTAL FACILITY RENOVATION HAS COMPLETED.
2. [Accelerator Division]
J-PARC ACCELERATOR DELIVERED 400-kW BEAM TO MLF USERS AND 320-KW BEAM
TO T2K EXPERIMENT.
3. [Particle and Nuclear Physics Division]
OBSERVATION OF A "K-PP"-LIKE STRUCTURE IN THE D(PI+, K+) REACTION.
NEUTRINO BEAM OPERATION WITH 320 KW BEAM POWER AND ACHIEVEMENT OF
1x1021 PROTONS ON TARGET.
PROGRESS IN MUON PARTICLE PHYSICS PROGRAMS.
THE WORKSHOP "FLAVORS OF NEW PHYSICS".
4. [Materials and Life Science Division]
1 MW EQUIVALENT PROTON BEAM PULSE WAS DELIVERED FOR THE FIRST TIME.
PROTON BEAM POWER FOR USER PROGRAM WAS RAMPED UP TO 400 KW.
168 NEUTRON PROPOSALS WERE APPROVED FOR THE 2015A PERIOD BY THE
NEUTRON SCIENCE PROPOSAL REVIEW COMMITTEE.
A FIRE FROM THE MUON D-LINE SEPTUM MAGNET POWER SUPPLY.
5. [Nuclear Transmutation Division]
CHALLENGES FOR LIQUID METAL APPLICATION IN HIGH TEMEPRATURE
CONDITION.
6. [Safety Division]
SYMPOSIUM ON SAFETY IN ACCELERATOR FACILITY.
J-PARC SAFETY MEASURES REINFORCED AFTER THE FIRE IN THE MATERIALS
AND LIFE SCIENCE EXPERIMENTAL FACILITY (MLF).
7. [Information System Section]
NEW NETWORK SEVICES "USER LAN" STARTED.
8. [Editorial Note]
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1. [Overview] by Yujiro IKEDA
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ACCELERATION OF A PROTON BEAM PULSE EQUIVALENT TO 1-MW WAS
SUCCESSFULLY DEMONSTRATED
THE HADRON EXPERIMENTAL FACILITY RENOVATION HAS COMPLETED
A proton beam pulse was accelerated to the power equivalent of
1-MW and injected to the mercury target. This achievement implies
great promise to realize the stable 1-MW beam supply to users soon.
All of the renovation to prevent a recurrence of similar
accidents has been completed at the Hadron Experimental Facility.
Because of the fire of a transformer in a power supply at the
muon area of the Materials and Life science Experimental Facility
(MLF), J-PARC suspended all the J-PARC beam operation for a month. All
facilities were inspected to confirm the safety. Further safety
measures against these potential risks in normal work were implemented
in the J-PARC safety procedures.
The 400-kW beam operation at MLF has started right after
restarting the user programs. At MR, proton beams at 320-kW power have
been delivered to the neutrino experiment. Very recently, 1.0 x 1021
protons on target was recorded.
Concerning the process for the full recovery from the accident at
the Hadron Experimental Facility on May 23, 2013, we reported critical
points, the measures for the incident, and the renewed procedures to
strengthen safety throughout J-PARC activities, to the Governor of
Ibaraki Prefecture, the Mayor of Tokai-village, and neighboring
municipalities. The report has been accepted for the safety measures
being properly implemented, and they kindly encouraged us to proceed
toward restart of the facility operation.
This is the final newsletter for me (Yujiro IKEDA) to report on
J-PARC to you. By taking this opportunity, I would like to express my
sincere gratitude to everyone: all of the J-PARC users, J-PARC staff,
High Energy Accelerator Research Organization (KEK), Japan Atomic
Energy Agency (JAEA), Ministry of Education, Culture, Sports, Science
and Technology (MEXT), Tokai village, Ibaraki prefecture, and others
for your enthusiastic support during my term as J-PARC Center
Director. Because of your great support and understanding, we
conquered big challenges. I hope you would like to give us your
continuing support and cooperation in the future.
Thank you very much.
I wish you all the best.
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2. [Accelerator Division] by Tadashi KOSEKI
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J-PARC ACCELERATOR DELIVERED 400-kW BEAM TO MLF USERS AND 320-KW BEAM
TO T2K EXPERIMENT
After the beam shutdown due to the fire at the muon facility of
the Materials and Life Science Experimental Facility (MLF), the J-PARC
accelerator resumed beam delivery to the T2K experiment on February 25
and to the neutron users of the MLF on February 26.
Before the restart of user operation for the T2K experiment,
accelerator studies were performed in the Main Ring synchrotron (MR)
for suppression of transverse beam instability and correction of
betatron resonances. For suppression of the beam instability,
parameters of two types of bunch feedback systems, patterns of rf
voltage, and sextupole magnet field were optimized in the timings of
beam injection and acceleration. As to correction of the resonance,
parameters of four skew-quadrupole magnets were optimized to correct
linear coupling resonance. As a result of these studies, the beam loss
in the MR was reduced and the beam intensity could be raised from 260
kW to 320 kW. The MR stably continued the beam operation with the
320-kW beam power for the T2K experiment until the end of March. The
number of delivered protons on the neutrino target exceeded 1x1021 on
March 26.
For the MLF users, the Rapid Cycling Synchrotron (RCS) increased beam
power from 300 kW to 400 kW on March 10. After one day of operation
with 400 kW, residual radioactivity was measured in the linac and the
RCS and it was confirmed that serious radioactivity was not observed
on the accelerator components. Since then, the RCS has delivered
stable 400 kW beam to the MLF users. The further increase of the beam
intensity from 400 kW to 500 kW is now planned for the middle of
April.
In the first week of April, accelerator studies of the linac and
the RCS were performed for stable beam operation with higher beam
intensity. For the MR, a newly-manufactured small kicker magnet was
installed during one-week maintenance. The magnet, which is called
compensation kicker can correct an extra kick of the circulating
bunches by imperfect magnetic field pattern of the injection kicker
system. The compensation kicker is expected to reduce beam loss
during beam injection and to lead an operation with a second harmonic
rf system, which can decrease the incoherent tune shift due to space
charge force. The second harmonic rf system is one of the key devices
to achieve higher beam power in the MR. The beam study with the second
harmonic rf system is planned in May.
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3. [Particle and Nuclear Physics Division] by Y. ICHIKAWA,
T. TSUKAMOTO, S. MIHARA and T. KOMATSUBARA
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OBSERVATION OF A "K-PP"-LIKE STRUCTURE IN THE D(PI+, K+) REACTION
(by Y. ICHIKAWA)
Study of di-baryon systems including strangeness, such as a
KbarNN system, is one of the most important topics in modern nuclear
physics, since introducing a new degree of freedom in the nucleus is
an important touchstone to understand hadron interactions based on
Quantum Chromodynamics.
A bound state of K-pp is predicted theoretically; however, its
existence is not clear experimentally. Measurements of the binding
energy and the width of the K-pp system would give fruitful
information particularly on the Kbar-N interaction.
We carried out the E27 experiment, at the K1.8 beam line of
J-PARC Hadron Experimental Facility using the d(pi+, K+) reaction at
1.69 GeV/c to investigate the K-pp system. In this reaction, a K-pp
bound state is expected to be formed through Lambda (1405) production
as a doorway. The key experimental technique is a coincidence of high-
momentum proton(s) at large emission angles, which enhances the
signal-to-background ratio.
We have measured a missing-mass spectrum in the pi+ d -> K+ + X
reaction by requiring two protons emission in the reaction for the
first time. The spectrum shows "K-pp"-like structure, which can be
interpreted as an evidence of "K-pp" bound state. The evaluated K-pp
binding energy is 100 MeV with a large width.
Other possibilities are also discussed. The results were published in
Progress of Theoretical and Experimental Physics (PTEP 2015, 021D01):
http://dx.doi.org/10.1093/ptep/ptv002.
NEUTRINO BEAM OPERATION WITH 320 KW BEAM POWER AND ACHIEVEMENT OF
1x1021 PROTONS ON TARGET (by T. TSUKAMOTO)
Neutrino beam line started operation on Jan. 12 but J-PARC
accelerators stopped from Jan.16 due to the fire of a power supply at
MLF. Neutrino beam operation was resumed from Feb. 25 and then soon
320 kW beam power was achieved. T2K experiment continued until the
morning of Apr.1 with anti-neutrino beam. The POT (protons on target)
so far reached at 1x1021 (http://t2k-experiment.org/2015/03/j-parc-
delivers-1x1021-protons-on-target-to-t2k/).
T2K collaboration released the result of measurements of neutrino
oscillation using data from the T2K long-baseline neutrino experiment
collected from 2010 to 2013, which corresponds to 6.6E20 POT. This
result was submitted to Physical Review D and http://arxiv.org/abs/1502.01550.
Takashi Kobayashi (KEK), Tsuyoshi Nakaya (Kyoto Univ.) and Masato
Shiozawa (ICRR) were awarded the 6th Yoji Totsuka prize (http://www.
hfbs.or.jp/orito-totsuka-prize-index.html (only in Japanese)). The
research theme for their award is "The observation of electron
neutrino appearance in a muon neutrino beam". They have played a
leading role in the T2K collaboration. Takashi Kobayashi (KEK) was
also chosen to receive the 21st Yomiuri Techno Forum Gold Medal Prize
("http://info.yomiuri.co.jp/event/2015/03/18.php).
PROGRESS IN MUON PARTICLE PHYSICS PROGRAMS (by S. MIHARA)
The COMET experiment aims at searching for the mu-e conversion
with a target sensitivity of 10^{-14} in Phase I. R&D of detectors to
identify the signal electrons has been conducted intensively by the
COMET collaboration. Facility construction at J-PARC is also in
progress.
In March 2015, one of the ingredients of the experiment, the muon
transport solenoid magnet, has been installed in the experimental area.
The solenoid magnet is to transport a high intensity muon beam from
a pion production target located in the primary beam line.
Conditioning of the magnet will follow in JFY 2015.
Preparation for a precision determination of the muon magnetic
and electric dipole moments is also in progress. The muon g-2/EDM
group is preparing for a technical design report. Initial acceleration
apparatus for muon acceleration R&D was assembled at MLF.
THE WORKSHOP "FLAVORS OF NEW PHYSICS" (by T. KOMATSUBARA)
The Workshop "Flavors of New Physics" was held on Mar. 9 and 10,
2015 at Tokai to discuss the potential of the new physics discoveries
at J-PARC and other frontier facilities. This workshop is supported by
KEK Theory Center.
http://kds.kek.jp/conferenceDisplay.py?confId=17388
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4. [Materials and Life Science Division] by Masatoshi FUTAKAWA
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1 MW EQUIVALENT PROTON BEAM PULSE WAS DELIVERED FOR THE FIRST TIME
PROTON BEAM POWER FOR USER PROGRAM WAS RAMPED UP TO 400 KW
1) Neutron Source
On January 12, 1MW equivalent proton beam pulses were
successfully delivered through the 3-GeV proton beam transport
facility to the neutron production mercury target for the first time.
A beam study was also conducted changing the power from 300 kW to 593
kW, and the intensities of cold and thermal neutrons were verified to
be proportional to the incident beam power.
Neutron production for the user program was started with a proton
beam power of 300 kW on February 26 after a month of suspension due
to the fire in the Materials and Life Science Experimental Facility
(MLF). The proton beam power was ramped up to 400 kW from March 10.
168 NEUTRON PROPOSALS WERE APPROVED FOR THE 2015A PERIOD BY THE
NEUTRON SCIENCE PROPOSAL REVIEW COMMITTEE
2) Neutron Instruments and Science
The general proposals for the 2015A period were reviewed by the
Neutron Science Proposal Review Committee, and finally 168 neutron
proposals were approved from 281 proposals by the MLF Advisory Board;
in addition, 33 proposals were reserved. The total competition rate
(requested / available beam time) is as high as 1.8.
The beam operation for RUN #60 originally scheduled from January
17 was canceled due to the fire in MLF. Parts of the beam time in RUN
#61 were also canceled due to the troubles at RCS and with the neutron
source. In total, 33.5 days of user beam time were lost. A number of
users, both domestic and abroad, were affected by these troubles. The
experiments that were canceled in RUN #60 and RUN #61 have been
carried over into the 2015A period. As a result, the period of 2015A
will be extended.
The J-PARC Center hosted the 14th Korea-Japan meeting on Neutron
Science from January 7 to 9 at Ibaraki Quantum Beam Research Center in
Tokai, Japan. The meeting had 29 participants from Korea and 50 from
domestic (including Korean scientists living in Japan), and had 56
presentations in oral sessions and a poster session. We discussed
further collaborations from various perspectives between Korea and
Japan in the meeting.
Construction of a polarized neutron chopper spectrometer, POLANO
at BL23 is in progress. A scattering chamber was delivered to the MLF
experimental hall on January 15. We are expecting to receive the first
neutron beam to POLANO at the beginning of JFY 2015.
A FIRE FROM THE MUON D-LINE SEPTUM MAGNET POWER SUPPLY
3) Muon Science Facility (MUSE)
A fire at the Second Experimental Hall of the Materials and Life
Science Experimental Facility, occurred at 15:01 on January 16. The
power supply for the septum magnet at the muon D-line caught fire. To
improve the stability of the current to the septum magnet, a newly
fabricated transformer was added to the existing power supply.
Electric power was turned on for the first time on January 16. In a
few minutes, the transformer started smoking and partly on fire.
Fortunately, the fire was immediately controlled by a hand
extinguisher. The fire arose from a mistake in the circuit design of
the power supply. The root causes of the incident were the
insufficient safety check of the circuit, and the failure of the
performance test of the whole system by the manufacturer. It was also
pointed out that the J-PARC staff had not been fully aware of risks
behind the power test in a radiation controlled area.
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5. [Nuclear Transmutation Division] by Toshinobu SASA
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CHALLENGES FOR LIQUID METAL APPLICATION IN HIGH TEMEPRATURE CONDITION
The operation of lead-bismuth eutectic (LBE) alloy for protecting
structural materials from corrosion at a high temperature is a key
technology to realize future accelerator-driven systems (ADS) for
nuclear transmutation and the J-PARC ADS Target test Facility (TEF-T).
Two sets of large-scale LBE loop equipment are in production and one
of them is a mock-up LBE loop for TEF-T primary loop system.
LBE is a fluid operated inside this loop in conditions of temperature
from 250 to 500 degree centigrade. The loop has a capacity to set the
temperature gradient of 100 degrees between hot-leg and cold-leg by
60kW electric heater and secondary water-cooling circuit. LBE will
circulate by electro-magnetic pump, which has the same specifications
for TEF-T target system. A flow meter using ultrasonic waves is used
to observe the flow rate of the LBE in the loop. A prototype of the
spallation target for material irradiation is also set up in the loop
to obtain a non-irradiated specimen to evaluate the irradiation
effects in flowing LBE environment.
The other loop is used for material corrosion studies at the
temperature range below 550 degree centigrade. The loop is made of 316
stainless steel except for high temperature sections made of T91, such
as a surge tank and integrated corrosion test sections. The loop will
be equipped with three test sections for corrosion tests at different
temperatures and LBE flow speeds, simultaneously.
Instruments to be needed to operate LBE loops are also under
development. Two kinds of oxygen potential sensors using pure bismuth
metal and platinum catalyst were fabricated. Because both sensors
are made by fragile zirconia tube, an LBE leak-free sensor housing is
also under development. In addition, the long-lasting ultrasonic flow
meter for LBE with thousands of hours of operation is under
development by collaboration with scientists for fast reactor
developments.
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6. [Safety Division] by Tetsuro ISHII
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SYMPOSIUM ON SAFETY IN ACCELERATOR FACILITY
The 2nd Symposium on Safety in Accelerator Facility was held on
March 6 at Tokai, and information on safety was shared with about 120
participants. The J-PARC Center reported the preventive measures
against the radioactivity leak incident in the Hadron Experimental
Facility and the recovery from the incident.
Activities on safety in the European Organization for Nuclear Research
(CERN) and Paul Scherrer Institute (PSI) were reported, followed by
the report on the topics of the International Technical Safety Forum
held on September, 2014. Safety issues as a user facility were also
reported from Research Center for Nuclear Physics (RCNP), RIKEN,
Spring-8, and the Materials and Life Science Experimental Facility
(MLF) of J-PARC.
J-PARC SAFETY MEASURES REINFORCED AFTER THE FIRE IN THE MLF
Causes of the incident from the safety management aspect:
1) Safety confirmation at the time of order was insufficient.
2) Risk estimation on the on-site test was insufficient.
The J-PARC Center has established a basic framework for safety
management and operated the facilities within the framework. However,
this time, the risk on the on-site test was overlooked because of a
low power device and as a result the work was "dropped off" from the
safety inspection.
The essential measure is to provide an adequate system to ensure
nothing is overlooked. We established two procedures as follows:
1) J-PARC Center Work Flow Standard, which is the crucial procedure
to ensure the safety works and stipulates the following processes at
the time of order:
i. Oblige a contractor to provide documents/references to confirm the
safety of equipment.
ii. Carry out safety confirmation by the J-PARC Center on the basis of
the documents/references.
2) Provision of Safety Confirmation in Division/Section, which picks
up high risks in the work and shares the information at regular
meetings in each division, in view of the 3H keywords ("Hajimete"
(first time), "Henko"(modification), "Hisashiburi"(first time after a
long interval)), to confirm safety under the responsibility of the
division.
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7. [Information System Section] by Atsushi MANABE
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NEW NETWORK SEVICES "USER LAN" STARTED
Since 2009, J-PARC has offered a Guest network (GWLAN) service.
The GWLAN is a wireless internet connection service for short-term
visitors available in almost all J-PARC buildings. The visitors are
requested to ask the J-PARC Users Office for a password before using
the GWLAN. At the beginning of 2015, a new network service called User
LAN started for J-PARC facility users. In the new service, users are
authenticated by the same ID and password which are used in the User
Support System for dormitory reservation and so on.
We hope the new system will contribute to improve usability of J-PARC.
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8. [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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