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J-PARC Project Newsletter
No.55, July 2014
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]
USER RUNS AT THE NEUTRINO EXPERIMENTAL FACILITY WERE RESTARTED ON MAY
26 FOLLOWING THE COMPLETION OF THE STRICT INSPECTION TO ENSURE THE
SAFETY.
ON MAY 23, THE WORKSHOP FOR FOSTERING SAFETY CULTURE AT J-PARC WAS
HELD IN ORDER TO IMPROVE SAFETY AWARENESS AND NOT TO FORGET THE
ACCIDENT AT THE HADRON EXPERIMENTAL FACILITY LAST YEAR.
2. [Accelerator Division]
ONE-MONTH LONG-TERM OPERATION OF THE RF-DRIVEN NEGATIVE ION SOURCE
AND THE NEW RADIO FREQUNECY QUADRUPOLE (RFQ) FOR PEAK CURRENT OF 50 MA
WAS SUCCESSFULLY ACHIEVED.
THE BEAM LOSS WAS REDUCED AND MINIMIZED IN HIGH INTENSITY BEAM STUDY
AT THE RAPID CYCLING SYNCHROTRON (RCS).
THE MR RESUMED BEAM DELIVERY TO THE T2K EXPERIMENT.
3. [Particle and Nuclear Physics Division]
NEUTRINO BEAM LINE OPERATION RESUMED.
RENOVATIONS FOR IMPROVEMENTS OF THE HADRON EXPERIMENTAL FACILITY ARE
IN PROGRESS.
PROTON BEAM ACCELERATION TEST FOR THE MU-E CONVERSION SEARCH
EXPERIMENT WAS CONDUCTED AT 8GEV SUCCESSFULLY.
PREPARATION FOR A PRECISE MEASUREMENT OF MUON MAGNETIC AND ELECTRIC
DIPOLE MOMENTS IS IN PROGRESS.
PROGRAM ADVISORY COMMITTEE MEETING.
4. [Materials and Life Science Division]
NEUTRON PRODUCTION WITH 300 KW PROTON BEAMS HAS STEADILY CONTINUED
FOR THE 2014A USER PROGRAM PERIOD FROM APRIL TO JUNE.
CONSTRUCTION OF THREE NEW INSTRUMENTS IS IN PROGRESS.
USER PROGRAM FOR 2014A HAS BEEN STARTED.
TWO HUNDRED EIGHTY NINE GENERAL NEUTRON PROPOSALS FOR 17 INSTRUMENTS
WERE SUBMITTED FOR 2014B PERIOD.
AT THE U-LINE, DAMAGE OF THERMAL INSULATION WINDOW WHICH PREVENTS
FROM THE HEAT RADIATION COMING FROM THE COMPONENTS AT ROOM TEMPERATURE
WAS FOUND.
5. [Nuclear Transmutation Section]
DEMONSTRATION OF LIQUID METAL HANDLING TECHNOLOGIES FOR TRANSMUTATION
EXPERIMENTAL FACILITY.
6. [Safety Division]
THE SAFETY INSPECTION OF NEW NEUTRON BEAMLINE IN MLF.
7. [Editorial Note]
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1. [Overview] by Yujiro IKEDA
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USER RUNS AT THE NEUTRINO EXPERIMENTAL FACILITY WERE RESTARTED ON MAY
26 FOLLOWING THE COMPLETION OF THE STRICT INSPECTION TO ENSURE THE
SAFETY
ON MAY 23, THE WORKSHOP FOR FOSTERING SAFETY CULTURE AT J-PARC WAS
HELD IN ORDER TO IMPROVE SAFETY AWARENESS AND NOT TO FORGET THE
ACCIDENT AT THE HADRON EXPERIMENTAL FACILITY LAST YEAR
1) The FY2015 budget proposal was prepared based on the principle
for user operation and the strategy for facility improvement at
J-PARC, which are (1) nine cycles of user operation, (2) development
of MR power supply, (3) instrumentation of neutron and muon beam-
lines, (4) improvement of sample environment, and (4) R&D for the
construction of the Accelerator Driven System (ADS). The total amount
of the proposed budget is more than 200 Oku-Yen. Due to a difficult
funding-situation of the government, drastic cutbacks on the budget
are expected.
2) Following the resumption of user operations at MLF on February
17, experiments were resumed at the Neutrino Experimental Facility
(NU) on May 26 after passing the strict safety inspection. Now, two
facilities were back on the track and renovation work on the Hadron
facility is being continued.
3) In this quarterly period, we experienced some problems in
several components, which led to a suspension of user operation.
However, overall we could have delivered appreciable amounts of beams
for users at 300 kW for MLF and 200 kW for NU. This thanks largely to
a sincere endeavor of the accelerator team. The experiments before the
summer shutdown were safely completed as scheduled on June 26.
4) The J-PARC center management team had face-to-face sessions to
discuss issues and also have suggestions directly from more than 200
J-PARC center staff members at the beginning of FY2014. These sessions
were being very effective to deepen our understanding and get clues to
improve the center.
5) Construction of the J-PARC Users Research Building (a
tentative name) has begun and will be completed by the end of March
2015.
6) On May 23, the first anniversary of the accident at the Hadron
Experimental Facility, we hosted the workshop for fostering Safety
Culture at J-PARC. We re-acknowledged that the development process of
counter and preventive measures was a very important learning process.
7) In order to improve the response to an emergency, we
periodically carried out emergency drills on the assumption of an
abnormal incident, which may cause radioactive materials leakage. The
most recent one was held at the Neutrino Experimental Facility on June
26. In this drill, the TV conference system was used for the first
time to be as a communication tool among local, JAEA, and KEK
headquarters, whereas JAEA and KEK were supposed to jointly establish
main headquarters in an emergency. We will continue to make an effort
to develop an efficient communication method to ensure safety for
users, workers, and neighbors.
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2. [Accelerator Division] by T. KOSEKI, H. OGURI, M. KINSHO
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ONE-MONTH LONG-TERM OPERATION OF THE RF-DRIVEN NEGATIVE ION SOURCE
AND THE NEW RADIO FREQUNECY QUADRUPOLE (RFQ) FOR PEAK CURRENT OF 50
MA WAS SUCCESSFULLY ACHIEVED (by H. OGURI)
On June 30, 2014, a HVTR (high voltage transformer) of the
klystron power supply #5 was broken due to the destruction of the
diode module. The failure was caused by applying overvoltage to the
capacitor. We are considering improvement of the transformer to
protect the device against the surge voltage. Recently, frequency of
the failure of the klystron power supply system tends to increase. We
will implement some countermeasures against the failure in the 2014
summer shutdown period.
For the upgrade of the linac peak current, a new front-end
system, which is composed of a cesium-seeded rf-driven negative ion
source and a new RFQ for the peak current of 50 mA, was tested in an
RFQ test stand. In June, 2014, a long-term continuous operation test
was performed. At the operation test, approximately 680 hours
continuous operation was achieved without any serious trouble. The
test was terminated at the end of June, and the installation of the
new front-end system in the linac tunnel was started on July 1, 2014.
THE BEAM LOSS WAS REDUCED AND MINIMIZED IN HIGH INTENSITY BEAM STUDY
AT THE RAPID CYCLING SYNCHROTRON (RCS) (by M. KINSHO)
User operation with beam power of 300kW has been performed with
no serious trouble except for only one trouble, which happened on the
15th of April. A choke transformer of a dipole magnet could not work
due to breakdown of an oil circulating pump which was used for
cooling. User operation could be restarted after replacing the broken
pump with new one, but this trouble disabled user operation for one
week.
High intensity beam study was performed for 3 days from the 28th of
June. Beam power could be increased to the equivalent of 573kW with
beam loss of 0.07% by tuning of injection beam and betatron tune.
The cause of beam loss is only charge-exchange foil scattering which
was used for charge exchange injection and it was found that beam loss
could be minimized in this beam study.
THE MR RESUMED BEAM DELIVERY TO THE T2K EXPERIMENT (by T. KOSEKI)
The MR resumed beam delivery to the neutrino beam line on May 16,
2014. After high power beam tuning of the MR and the neutrino beam
line, user operation for the T2K experiment started with a beam power
of 210-230 kW and continued until the morning of June 30, 2014.
In the high power beam operation, a bunch-by-bunch feedback system
suppresses transverse beam instabilities, which are observed during
the injection and beginning of acceleration. The system, however, can
only damp the coherent dipole motion of the bunch, and internal bunch
oscillations still remain and occasionally causes the beam loss.
Recently, a new bunch feedback system, called intra-bunch feedback
system was developed. The intra-bunch feedback system is more wideband
and precise system than the bunch-by-bunch system and can suppress the
internal bunch oscillations. The intra-bunch feedback system was
switched in the user run since the end of May. The bunch feedback
technique is quite effective and plays an important role at present
and in future high power operation.
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3. [Particle and Nuclear Physics Division] by T. TSUKAMOTO, K. OZAWA,
S. MIHARA, T. KOMATSUBARA
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NEUTRINO BEAM LINE OPERATION RESUMED (by T. TSUKAMOTO)
During a long period of shutdown, all three electromagnetic horns
with graphite target and an OTR (Optical Transition Radiation) proton
profile monitor attached to the most upstream horn were successfully
replaced. The new horns have higher cooling capacity than the old ones
and can now accept the beam power of 750kW. Because all the replaced
components had been highly radioactive, the replacement work had to be
done by remote handling. The remote maintenance scenario and the
hardware system have been very carefully designed and developed for
many years, and they led to this success.
After commissioning to check the functionality of all the beam
line components, the neutrino beam line operation was resumed on May
26 to supply neutrino beam for the T2K experiment. The beam power was
smoothly increased up to about 220kW, which is the same level as the
last operation in 2013. The first anti-neutrino beam operation in T2K
was carried out in June. Neutrino beam operation which was accumulated
with 0.57x10^20 POT (protons on target) before summer maintenance
finished on June 26.
RENOVATIONS FOR IMPROVEMENTS OF THE HADRON EXPERIMENTAL FACILITY ARE
IN PROGRESS (by K. OZAWA)
Renovation work to improve radiation safety of the Hadron
Experimental Facility is currently underway. It includes the
installation of the ventilation equipment with filters in the
experimental hall and the improvement in the air tightness of the
primary beam line. Machine buildings beside the hall are also being
upgraded.
PROTON BEAM ACCELERATION TEST FOR THE MU-E CONVERSION SEARCH
EXPERIMENT WAS CONDUCTED AT 8GEV SUCCESSFULLY
PREPARATION FOR A PRECISE MEASUREMENT OF MUON MAGNETIC AND ELECTRIC
DIPOLE MOMENTS IS IN PROGRESS (by S.MIHARA)
The COMET experiment aims at searching for the mu-e conversion,
strictly forbidden in the standard model (SM), with a target
sensitivity of 10^{-14} in Phase I and 10^{-16} in Phase II. The
experiment requires the proton beam extracted at 8GeV for producing
muons with a significant suppression of antiproton-induced
backgrounds. Protons of 8GeV are extracted without destroying its
bunched time structure for producing the pulsed-muon beam. This pulse
structure has to be extremely precise; namely there should not be
proton leakage from a pulse to in-between pulses above the level of
10^{-9} to 10^{-10}. An acceleration test and beam property
measurement at 8GeV were conducted with help of the accelerator group
in May. The leakage ratio, called extinction factor, was measured to
be well below the level of 10^{-11} at 8GeV using a beam monitor
installed in the abort line. R&D of detectors identifying the signal
electrons is also in progress along with superconducting magnet coil
production.
Preparation of the muon magnetic and electric dipole moments
measurement is also in progress. A series of test experiments has been
conducted to verify an efficient production of muonium in an aerogel
plate with many tiny holes that has been used as a muon source, at
J-PARC MLF in May. A prototype of the silicon strip detector with a
new read-out electronics to measure the positron tracks from muon
decays was successfully tested at MLF in June.
Related Meeting
The COMET group had a collaboration meeting at the Institute of
High Energy Physics (IHEP) in China in May and new collaborators from
Nanjing, Peking, and North China Electric Power Universities were
approved to join the collaboration.
PROGRAM ADVISORY COMMITTEE MEETING (by T. KOMATSUBARA)
This committee evaluates and assesses joint-usage proposals on
the experiments at the J-PARC Main Ring as well as important issues to
push forward the research program. The 18th meeting was held from May
14 through 16, and the comments and evaluations will be summarized as
the meeting minutes in the near future.
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4. [Materials and Life Science Division] by Masatoshi ARAI
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NEUTRON PRODUCTION WITH 300 KW PROTON BEAMS HAS STEADILY CONTINUED
FOR THE 2014A USER PROGRAM PERIOD FROM APRIL TO JUNE
1) Neutron Source
The mercury target has steadily run with the 300 kW proton beam
for the 2014A user period from the 14th of April to the 24th of June
during which the gas micro-bubble injection successfully continued to
mitigate the pressure waves generated in mercury. Other components
such as the cryogenic hydrogen moderators and water cooling systems
have also worked without any trouble. As a result, a 59-day neutron
production was completed for the 2014A user period as of the 24th of
June, and 6.5 days were cancelled in April due to a trouble occurring
at the 3-GeV RCS.
Fabrication of an advanced target vessel, which has a double-
walled structure with a narrow channel width of 2 mm at the proton
beam injection portion, has been approaching completion since it began
in the summer of 2013.
CONSTRUCTION OF THREE NEW INSTRUMENTS IS IN PROGRESS
USER PROGRAM FOR 2014A HAS BEEN STARTED
TWO HUNDRED EIGHTY NINE GENERAL NEUTRON PROPOSALS FOR 17 INSTRUMENTS
WERE SUBMITTED FOR 2014B PERIOD
2) Neutron Instruments and Science
Construction of three new instruments BL06 (Vin Rose, Spin Echo
Spectrometers), BL22 (Pulsed Neutron Imaging Instrument) and BL23
(POLANO, Polarized Neutron Spectrometer)) is in progress. Beam
inspection on radiation shielding of three instruments was conducted
by Nuclear Safety Technology Center on the 22nd of April and passed
without any serious problems.
User program for 2014A was started on the 21st of April. It will
be continued till December after four months break in summer.
We called the general proposals for 2014B (from the end of 2014).
Call for proposal was closed in the middle of June and 289 neutron
proposals were submitted. We have recorded the highest number of
proposals again. Those proposals will be sent to the Neutron Science
Proposal Review Committee for reviewing process.
AT THE U-LINE, DAMAGE OF THERMAL INSULATION WINDOW WHICH PREVENTS
FROM THE HEAT RADIATION COMING FROM THE COMPONENTS AT ROOM WAS FOUND
3) Muon Science Facility (MUSE)
In the category of the muon user's program 2014A, 26 proposals
were submitted. At the D-Line, not only muSR experiments, but also
non-destructive element analysis utilizing negative muons have been
performed at the D1 area, or D2 area, without any trouble, yielding a
variety of interesting results.
At the U-Line, the front-end superconducting magnet in the
superconducting curved solenoid transports intense surface muons
efficiently from the proton beam line to the experimental area. It was
found that the front-end superconducting magnet has difficulty to cool
down below the superconducting temperature. By inserting a fiber
telescope into the superconducting curved solenoid, it was finally
revealed that thermal insulation window which prevents from the heat
radiation coming from the components at room temperature, was broken.
We have to remove the shields in the vicinity of the superconducting
curved solenoid, to get access to it. Therefore, we are planning to
fix it as soon as beam will stop in the beginning of July, 2014.
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5. [Nuclear Transmutation Section] by Toshinobu SASA
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DEMONSTRATION OF LIQUID METAL HANDLING TECHNOLOGIES FOR TRANSMUTATION
EXPERIMENTAL FACILITY
The Materials and Life Science Experimental Facility (MLF) uses a
liquid metal as a spallation target in J-PARC. We can apply many
experiences for design and operation of liquid metal spallation
target. However, in the case of Lead-Bismuth Eutectic alloy (LBE),
which is a primary candidate of the spallation target and coolant of
future Accelerator-Driven System (ADS), the melting point is much
higher than room temperature and LBE requires special treatment to
keep it in liquid phase. In an ADS Target Test Facility (TEF-T), which
is a part of Transmutation Experimental Facility (TEF), LBE loop will
be installed as a liquid metal spallation target to perform the
engineering tests for future ADS studies.
Last year, we manufactured a special test equipment to establish
the handling technologies of LBE by remote operation. In the
equipment, the flange itself is designed based on the existing MLF
mercury loop. We added a detachable preheating device that is designed
based on the experiences from Fast Breeder Reactor "Monju". We
performed a first test to handle remote preheating system named
"Packaged Heater" by master-slave manipulator (MSM). Several
modifications, which requires to handle a "Packaged Heater" safely by
MSM, were indicated and revision of fully remote handled "Packaged
Heater" is underway. The equipment is also used to demonstrate process
instrumentations that are necessary to operate LBE target loop.
Results obtained from the equipment will be reflected to the newly
prepared LBE target mockup loop.
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6. [Safety Division] by Tetsuro ISHII
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THE SAFETY INSPECTION OF NEW NEUTRON BEAMLINE IN MLF
The safety inspection of the new neutron beamline (BL06) in the
Materials and Life Science Experimental Facility was successfully
conducted on Apr. 25 by the Nuclear Safety Technology Center (NUSTEC).
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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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