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J-PARC Project Newsletter
No.67, July 2017
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]
EVENTFUL SUMMER BEGINS.
2. [Accelerator Division]
OPERATION STATUS OF THE ACCELERATORS.
3. [Particle and Nuclear Physics Division]
SUCCESSFUL DATA-ACQUISITION AT THE HADRON EXPERIMENTAL FACILITY.
T2K EXCLUDED CP CONSERVATION AT 95% CL WITH DOUBLED STATISTICS.
STATUS OF THE COMET (COHERENT MUON TO ELECTRON TRANSITION) (E21).
STATUS OF THE MUON G-2/EDM (E34).
4. [Materials and Life Science Division]
STEADY NEUTRON PRODUCTION OPERATION WITH 150 KW PROTON BEAM WAS
ACHIEVED.
CONSTRUCTION AND COMMISSIONING OF TWO NEW BEAM LINES HAVE
PROGRESSED.
CALL FOR GENERAL PROPOSALS FOR 2017B PERIOD WAS CLOSED AND WE
RECEIVED TWO HUNDRED EIGHTYSIX NEUTRON PROPOSALS.
NEUTRON ADVISORY COMMITTEE (NAC) FINAL REPORT WAS RECEIVED.
STRUGGLE FOR ULTRA-SLOW MUONS CONTINUED.
5. [Nuclear Transmutation Division]
FULLY REMOTE REPLACEMENT OF THE LEAD-BISMUTH EUTECTIC ALLOY (LBE)
SPALLATION TARGET.
6. [Safety Division]
FY2017 SAFETY DAY AT J-PARC.
THE SAFETY INSPECTION WAS SUCCESSFULLY CONDUCTED.
7. [Editorial Note]
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1. [Overview] by Naohito SAITO
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EVENTFUL SUMMER BEGINS
We have entered the summer maintenance period after the
successful running in all facilities. As reported in the later
sections, Materials and Life Science Facility (MLF) achieved its
availability of 93.4%, which is remarkably high as an accelerator
based neutron and muon facility. There was a long break in the Hadron
Experimental Facility (HEF) due to the breakdown of the electro-
static septum (ESS) for the slow extraction, which leads to a
regrettable availability of 45%.
Nonetheless we were able to complete the beam exposure to the
emulsions of E07 (investigation of double-strangeness nuclei), which
waited for long years. Other experiments, including KOTO experiment,
have accumulated more events. The neutrino facility received the
highest beam power of 485 kW which leads the T2K experiment to double
the statistics.
Moreover, there was a press release of even more confirmed CP
violation at 95% confidence level. The results were officially
released at a KEK colloquium, and will be reported at the Lepton-
Photon Conference in Guangzhou, China from August 7th. The release
can be found at
(Japanese) http://j-parc.jp/ja/topics/2017/Press170804.html
(English) http://www.kek.jp/en/NewsRoom/Release/pressrelease20170808en.pdf
Now those facilities and the accelerator facility are on summer
maintenance aiming for more stable beam time starting in October.
Interest from industrial users at MLF is increasing. The
workshop on MLF industrial use was held right after the general
assembly of the industrial users society for neutron application on
July 20-21 at Akihabara. The meeting was attended by 452 total
participants which is 42% more compared to last year. One of the
highlights was the special invited talk by Dr. Noboru Kikuchi, the
president of Toyota Central R&D Labs. Inc. on "Neutron Application at
Toyota Central Laboratory".
Last but not least, the Memorandum of Collaboration (MoC)
between J-PARC and the European Spallation Source was signed in front
of Japanese Prime Minister Shinzo Abe and Swedenfs Prime Mister Stefan
Lofven on July 9th in Stockholm. Both labs will continue to work
closely as global partners for the neutron science around the world.
The movie of the ceremony can be found at the Swedish government
website:
http://www.government.se/articles/2017/07/free-trade-agreement-and-export-issues-on-agenda-as-prime-minister-met-japanese-counterpart/
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2. [Accelerator Division] by Kazuo HASEGAWA
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OPERATION STATUS OF THE ACCELERATORS
We delivered beam from March as Run#74 until the morning of
April 19 as scheduled. After the replacement of the ion source and
short maintenance work, we started new Run#75 as a linac and 3 GeV
synchrotron (RCS) study time. We started user operation for the
Materials and Life science experimental facility (MLF) in the evening
of April 26 as scheduled at the beam power of 160 kW. Since then, we
delivered beams to the MLF almost on schedule until the summer
shutdown.
The Main Ring (MR) delivered beams to the neutrino experimental
facility (NU) until April 12 at the beam power of 460-470 kW, which
was slightly increased in January. Then we switched the extraction
mode from fast to slow and started tuning for the hadron experimental
facility (HD). We smoothly ramped up the power to 44 kW, which
exceeded the previous power of 42 kW in June 2016. But during the
startup after the scheduled maintenance day of April 26, one of the
Electro-Static Septum (ESS) had a failure, and beam operation was
suspended. We coped with this issue for about three weeks, then we
managed to start beam tuning on May 19. We had an inspection by the
regulation authority on May 31, and then started user operation on
June 2. We delivered beam to HD without long interruptions, though
the beam power was slightly down to 37 kW.
The user operation was to end on the morning of June 28 in the
original schedule, but it was extended by three and four days for
the HD and for the MLF respectively. We had an accelerator study time
until the morning of July 6 and stopped operation for the summer
shutdown. The Run#75 was the longest run in the J-PARC beam operation
history. A new record of 77 continuous operation days of the ion
source was also performed.
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3. [Particle and Nuclear Physics Division] by T. NOMURA,
T. TAKAHASHI, T. ISHIDA, S. MIHARA, AND T. MIBE
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SUCCESSFUL DATA-ACQUISITION AT THE HADRON EXPERIMENTAL FACILITY
(by T. Nomura and T. Takahashi)
In May and June, J-PARC delivered slow-extraction beams to the
Hadron Experimental Facility. The beam period was originally
scheduled from the middle of April. A serious trouble of a slow-
extraction device at the accelerator occurred, and it causes a delay
in the beam delivery for one month and the decrease of the beam
power. The trouble was fixed at the end of May. Stable operation of
the accelerator was achieved in June. In this period, two major
experiments such as the KOTO experiment and the E07 experiment were
carried out.
The KOTO experiment, which studies a CP-violating ultra-rare
decay of the neutral kaon, restarted taking physics data from the
beginning of June. A highlight for this period is an upgrade of the
trigger scheme.
The experiment installed newly-developed hardware that can count
the number of photons hitting the electromagnetic calorimeter with
the latency of ~2 microseconds. Thus, it can select interesting
events at an early stage of the data acquisition. It enables not only
efficient accumulation of the main physics data but also simultaneous
data collection for other interesting decay modes. As of late June,
KOTO is steadily accumulating data with this new scheme.
The E07 experiment was performed at the K1.8 beam line to study
properties of double-strangeness nuclei in detail. In the experiment,
Xi-hyperons were produced by applying K- beams to a diamond target
and the Xi- hyperons produced double-strangeness nuclei in nuclear
emulsions. Total 100 stacks of the emulsions were successfully
exposed and we expect to get 100 times larger statistics than we had
previously.
T2K EXCLUDED CP CONSERVATION AT 95% CL WITH DOUBLED STATISTICS
(by T. Ishida)
The neutrino beam-line operation in the neutrino mode (forward
horn current mode) successfully completed on April 12. The maximum
beam power has reached to 485 kW, and Protons On Target (POT) since
last October has been accumulated to 7.3 x 10^20. As a result, total
POT in neutrino mode since the start of the experiment (Jan. 2010)
has successfully been doubled to 14.9 x 10^20. With the existing
anti-neutrino mode data, total POT is now counted as 22.5 x 10^20. At
present, analysis upgrades are ongoing for upcoming summer
conferences(*).
(*)While editing this newsletter issue there was a press release on
August 4, which can be found at
(Japanese) http://j-parc.jp/ja/topics/2017/Press170804.html
(English) http://www.kek.jp/en/NewsRoom/Release/pressrelease20170808en.pdf.
T2K excluded CP conservation at 95% CL with doubled statistics.
The results were officially released at a KEK colloquium and also
reported at the Lepton-Photon Conference in Guangzhou, China held
from August 7. http://indico.ihep.ac.cn/event/6183/
T2K has published its first results in the search for CP
violation in neutrino oscillations using appearance and disappearance
channels for neutrino- and antineutrino-mode beams since last summer
(15.0 x 10^20 POT). The CP conservation hypothesis has been excluded
at 90% C.L.. The article has appeared as an Editors Suggestion of
Physical Review Letters in the April 14 edition.
For more information visit:
https://journals.aps.org/prl/issues/118/15
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.151801
http://t2k-experiment.org/ja/2017/06/first-t2k-cp-violation-search-published/
STATUS OF THE COMET (COHERENT MUON TO ELECTRON TRANSITION) (E21)
(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 collaboration is intensively preparing
detectors toward the start of the experiment along with construction
of the facility to provide pulsed muon beam dedicated for the
experiment.
The experiment needs a proton beam with a pulse-to-pulse width of
about 1 micro sec and extremely small particle contamination in
between two consecutive pulses for producing the muon beam: these are
mandatory to reduce the main background in the search. The ratio of
the number of particles in between pulses is called an extinction
factor, which must be smaller than 10^{-9~-10} to reach the target
sensitivity of the experiment. Studies on the extinction factor of
the COMET proton beam have been conducted in collaboration with the
J-PARC accelerator group. Recently, diamond detector technology has
been introduced to measure the time structure of the proton beam as
the diamond detector is highly radiation tolerable with a fast
response. The initial irradiation test of the proton beam on the
diamond detector was successfully carried out in May. Further R&D
continues to build a profile monitor using diamond detector
technology as well as the extinction monitor R&D.
The COMET group had a collaboration meeting at the end of May
2017 in J-PARC. Status and schedule of the experiment preparation
was discussed by more than 40 participants from all over the world.
STATUS OF THE MUON G-2/EDM (E34) (by T. MIBE)
The E34 collaboration prepares for precision measurements of
muon anomalous magnetic moment and electric dipole moment. The
collaboration works for refinement of technical design and resolving
issues that were pointed out by the focused review in Nov. 2016. The
first test of muon acceleration with Radio Frequency Quadrupole (RFQ)
is scheduled in November, 2017 at the Materials and Life Science
Experimental Facility (MLF). Towards this test, data for
characterization of the low-energy muon beam for the input to the RFQ
was collected at MLF in March. A test module for the positron
tracking detector was developed with a silicon-strip sensor fully
connected with readout chips, which were prepared and tested with the
muon beam at MLF in June. Several new silica aerogel samples with
laser-ablated holes were produced for the measurements of muonium
production yield and its polarization from late June at TRIUMF.
The collaboration meeting was held in early June at the J-PARC
research building. The new collaboration chair, a spokesperson, and
executive board members were officially appointed in the meeting.
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4. [Materials and Life Science Division] by Toshiji KANAYA
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STEADY NEUTRON PRODUCTION OPERATION WITH 150 KW PROTON BEAM WAS
ACHIEVED
1) Neutron Source
Steady neutron production operation was achieved with 150 kW
proton beams for the 2017A user program from April 1 to the end of
June. Scheduled beam time of 66 days finished with good availability
of 93.4% so far. From July, maintenance of neutron source components
and 3 GeV proton beam transport facility is in progress.
Fabrication of the next target vessel has almost completed the
most important stage, which was assembling and welding of the main
body including the mercury vessel and the water shroud. Assembling of
the conventional parts such as piping and flanges to the main body is
in progress as the final stage of the fabrication.
The new target vessel will be in use from the autumn run.
CONSTRUCTION AND COMMISSIONING OF TWO NEW BEAM LINES HAVE PROGRESSED
CALL FOR GENERAL PROPOSALS FOR 2017B PERIOD WAS CLOSED AND WE
RECEIVED TWO HUNDRED EIGHTYSIX NEUTRON PROPOSALS
NEUTRON ADVISORY COMMITTEE (NAC) FINAL REPORT WAS RECEIVED
2) Neutron Instruments and Science
Construction of POLANO (the polarized neutron spectrometer at
BL23) continues in the collaboration between KEK and Tohoku Univ.,
and on-beam performance test on the part of installed components has
been started from June. Commissioning work of VIN ROSE (the spin-echo
suite at BL06) progressed and part of the instrument will open to the
user program from the 2017B period.
Call for general proposals for the 2017B period was closed on
June 7 and we received 286 neutron proposals. Those proposals will be
sent to the Neutron Science Proposal Review Committee for reviewing
process. Final results will be sent to users in September. Apart from
this ordinary scheme, we newly called for general neutron proposals
for long term starting from 2017B with three-year validation and
received 24 proposals. Nine of them were selected to advance to
hearing examination in the Sub-Committee/ Expert panel. The number of
neutron proposals received in both schemes for general proposals
totaled 310, which is our record exceeding 289 in 2014B. We hope that
installation of new designed target expected in this summer shut-down
will be complete and increase of beam power will be accepted by
users. We received a final report of Neutron Advisory Committee (NAC,
Chair; Dr. Robert McGreevy (Director of ISIS)) which was held in
February 20-21, 2017 at the J-PARC Center. On a review of our efforts
to strengthen the facility, the Committee appreciated reliable
operation to conserve the remaining spare target, high probability of
success in solving the water shroud problem with the new fabrication
of targets completed structural analysis and mock-up testing. They
recommended us to operate the Materials and Life Science Experimental
Facility (MLF) at a mid-range constant power near 500 kW for at least
a year instead of aggressively aiming for 1 MW operation, considering
the following points: user programs, maturity of support systems and
science production, establishing a proven base reliability target
power level, and helping to promote understanding about power-
dependent cavitation damage.
Although the build-up of a high quality instrument suite from
the start of MLF has been impressive, existing beamlines are not yet
fully performing scientifically. The committee recommended giving
priority to develop the scientific productivity of the existing
instruments, rather than building new instruments for the next few
years. They also supported us for forming cross-organizational
science groups towards increasing the emphasis on science and so
raising scientific profile of MLF. On the Science Promotion Board
(SPB) which has been recently organized to monitor, evaluate, and
advise a scientific driven agenda of MLF, it is recommended that SPB
members should not necessarily be neutron users - advice from
synchrotron users or theoreticians/modelers would also be valuable.
On the other hand, the committee recognized that the separation
into different organizations is still a problem although there has
been progress towards improved cross-organizational working and the
support levels across instruments are still very inconsistent.
The committee advised the following improvements to MLF.
1) MLF is still in the transition from construction to operation.
This transition is always difficult for facilities.
2) MLF needs to always remember that the priority is to produce
science, neither to deliver accelerator or target power nor to
develop instruments.
3) MLF needs to build a productive scientific user program with
strong support. A critical analysis of the causes of low productivity
should be carried out.
4) Industrial use is clearly a high priority for the government. But
non-proprietary use must have some visible output.
We appreciate all the advice from the NAC.
STRUGGLE FOR ULTRA-SLOW MUONS CONTINUED
3) Muon Science Facility (MUSE)
Since the successful generation of ultra-slow muons (USMs) at
MUSE in FY2015, experimenters have been making ceaseless endeavors
to ramp up the USM yield to the level needed for practical
applications. They are still in a long crucial stretch, however, they
are fiddling with so many devices including muon beamline (U-line,
consisting of superconducting solenoids and axial-focusing solenoids)
for optimizing the muon stopping in the hot tungsten target, complex
laser systems for maximizing the ionization efficiency of thermal
muonium (Mu) atoms, and electrostatic lens and quadrupoles for the
efficient transport of the ionized USMs to the sample position.
Among these, the current bottleneck is the vacuum-ultraviolet (VUV)
laser power for the Mu ionization.
It requires a crystal vendor to deliver a high-quality ceramic
crystal of yttrium-gallium-aluminum-garnet (YGAG) for the final laser
amplifier hampering improvement of total ionization efficiency for
the unfulfilled promise. In addition, relatively low proton beam
power (~150 kW) places a further limit to the net USM yield by
reducing the incident surface muon flux, making the entire tuning
work time-consuming.
It is desperately hoped that the crystal vendor will find a
solution to fabricate good enough YGAG crystals shortly.
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5. [Nuclear Transmutation Division] by Toshinobu SASA
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FULLY REMOTE REPLACEMENT OF THE LEAD-BISMUTH EUTECTIC ALLOY (LBE)
SPALLATION TARGET
Accelerator-driven system (ADS) designed by JAEA applies the LBE
for spallation target and coolant. The most serious issue to handle
LBE is the compatibility with versatile materials.
ADS Target Test Facility (TEF-T) in Transmutation Experimental
Facility (TEF) program equips a 250 kW LBE spallation target for
material irradiation to prepare design database for ADS. Because the
focused beam will be injected to increase irradiation damage on
materials, TEF-T target should be replaced annually. Normally, flange
connection is used for such periodic replacement components. However,
in this case, it is difficult to use flange to LBE spallation target
loop because of the higher operation temperature and corrosive
properties of LBE. Higher operation temperature gives specific heat
expansion and heat deformation not only for flange but also for other
loop components, such as piping, connection bolts/nuts and metal
gaskets. We already tried to apply remote flange system used in
J-PARC mercury target but it does not work well in high temperature
range above 200 degrees centigrade. Moreover, material
incompatibility of LBE sometimes gives serious leakage by corrosion
damage of gaskets. Considering above reasons and expert suggestions
by TEF Technical advisory committee (T-TAC), we selected welding
connection to replace TEF-T spallation target.
Target system design was changed to replace the target by
connection with welding. A space for remote operation to cut LBE loop
and weld new target unit is prepared in biological shield region.
Movable shields are allocated and related components such as package
heater for long straight piping, automatic welding machine, and pipe
cutting machine that can prevent scatter of cutting dust which are
under development to use them by master-slave manipulators. Test
stands are in preparation to perform the entire tests by remote
handling systems.
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6. [Safety Division] by Yukihiro MIYAMOTO and Kotaro BESSHO
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FY2017 SAFETY DAY AT J-PARC
The J-PARC Center has held Workshop for Fostering Safety Culture
every year around May 23 on which the radioactive material leak
incident occurred at the Hadron Experimental Facility in 2013. This
year, "Safety Day at J-PARC" was established as a day when every
staff places his/her priority on safety activities and FY2017 Safety
Day was set to May 25.
In the morning at the day, a meeting for exchanging information
on safety efforts was held. Various information on safety was
introduced, and a scientific talk on the radioactive material leak
incidents in 2013 was given by a staff member of the Radiation Safety
Section. Furthermore, recent good-practice efforts implemented at the
Hadron Experimental Facility was introduced by the Hadron Section. On
the afternoon, the 5.23 Workshop for Fostering Safety Culture was
held at the auditorium of the Nuclear Science Research Institute.
The main talk entitled "SAFETY treasured at the Tokyo Disney
Resort" was given by Mr. Hidemi Ishizaka, Improving Service & Peace.
He spoke based on his experiences on working as a person in charge of
various attractions at the Tokyo Disney Resort that smiles of staff
members and good atmosphere are important for keeping safety working
environment.
THE SAFETY INSPECTION WAS SUCCESSFULLY CONDUCTED
The safety inspection of the Hadron Experimental Facility (HD)
was successfully conducted, and the certificate was issued on June 2
by Radiation Management Institute, Inc. The inspection items were the
shielding construction prepared for a new beam line and the radiation
dose measurements around it in HD.
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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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