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J-PARC Project Newsletter
No.68, October 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]
BACK TO OPERATION AFTER THE SUMMER MAINTENANCE.
2. [Accelerator Division]
MAINTENANCE AND IMPROVEMENT WORK DURING SUMMER SHUTDOWN.
3. [Particle and Nuclear Physics Division]
ACTIVITIES OF HADRON EXPERIMENTAL FACILITY IN THIS SUMMER.
BEAM WINDOW REPLACEMENT AND NEUTRINO BEAM INSTRUMENTATION WORKSHOP.
STATUS OF COMET.
STATUS OF THE MUON G-2/EDM (E34).
PROGRAM ADVISORY COMMITTEE MEETING.
4. [Materials and Life Science Division]
VARIOUS MAINTENANCE WORK OF NEUTRON SOURCE COMPONENTS WAS
COMPLETED.
NEW NEUTRON PRODUCTION TARGET VESSEL WILL BE READY TO USE AFTER
REPLACEMENT.
PROPOSALS FOR 2017B PERIOD WERE REVIEWED.
REPORT MEETING OF INDUSTRIAL APPLICATION WAS HELD.
CONSTRUCTION OF ELECTRIC POWER SUBSTATION FOR H-LINE IS IN PROGRESS.
5. [Nuclear Transmutation Division]
SCOOPING UP THE 10 W BEAM FROM 250 kW PROTON STREAM (3).
6. [Safety Division]
FY2017 MEETING OF THE LIAISON COMMITTEE ON SAFETY AND HEALTH FOR
CONTRACTORS WORKING AT J-PARC.
7. [Editorial Note]
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1. [Overview] by Naohito SAITO
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BACK TO OPERATION AFTER THE SUMMER MAINTENANCE
J-PARC is back to its user operation since mid-October after
three months of summer shutdown for maintenance. One of the
highlights of this summer was the installation of the newly-made
target vessel for neutron production at the MLF (target#8).
Target#8 is a new design after the water leakage of the target#7
back in November, 2015. Because the leakage was due to incomplete
treatment of the joint region, e.g. welding lines, the new target#8
has a monolithic structure in the most severe area of heat stress.
The target has been inspected very carefully not only after
fabrication but also during the fabrication process at several
stages. Since the first time of introduction of beam to the
target#8, we have been monitoring various aspects of the target
vessel such as temperature at several locations and vibrations
measured by the Doppler-shift method, to make sure the target is
functioning as we have expected based on the design.
We also increased the understanding of target#8 by changing the
power, targeting point, and the shape of the beam leading to
different a heat load onto the vessel. We will keep our eyes on the
target vessel to maximize the life of the target as well as the
knowledge of the target materials for even more robust target
systems.
Other facility status is described in the following articles.
Basically they are in good condition to produce more results with the
highest available beam power. While the data are being accumulated
for more upcoming results, we have a new press release on the
electron spin configuration in materials probed by the neutron
transmission measurements. Stay tuned for more protons on the
targets, more results, and more excitement!
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2. [Accelerator Division] by Kazuo HASEGAWA
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MAINTENANCE AND IMPROVEMENT WORK DURING SUMMER SHUTDOWN
Beam operation was suspended for maintenance during the summer
shutdown from July to September. Maintenance of the components and
various improvement work were conducted in the accelerator
facilities.
The linac started beam commissioning in 2006 and some of the
components are approaching the end of life. For the 324-MHz radio
frequency systems, we are using 20 klystrons, and we have replaced
some of them in these years based on the conditions. As preventive
measures during this summer shutdown, we have replaced four
klystrons. Most of them exceeded operation time of 55,000 hours and
have shown lowering of their performance. We have performed
reliability improvement work continuously such as cleanup inside the
separated type drift tube linac cavities and cooling water flow
stabilization.
At the 3 GeV Rapid Cycling Synchrotron (RCS), radioactivity of
some of the components is increasing as the accelerated proton number
accumulates. One of the advance preparations, a maintenance booth, in
which air can be fed to the air conditioning system and inspected by
the radiation monitor, has been constructed to repair the pumps
contaminated by tritium. Last summer, we installed a collimator which
does not have a movable function to keep the trouble in April 2016
from reoccurring. We had a plan to install a new collimator with
movable functions this summer, but we found some improvement points
for the current contact parts, and the installation has been
postponed. It will not affect the power level for the schedule of the
upcoming year.
At the Main Ring synchrotron (MR), one of the main tasks is a
reallocation of the collimator system. We had five collimators and we
will replace two of them by the four-axis movable type for final
power goal in the future. For minimizing the radiation exposure by
the residual dose during the rearrangement of the collimators, one
fixed type collimator was just removed and replaced with a four-axis
type. After the electric short trouble by cutting wires of the
Electro-Static Septum (ESS) in April, we have treated a new ESS made
of Titanium off-line. Based on the analysis of the trouble, some
modifications around the electrode have been made to prevent the
electric short by the broken wire and to detect the sign of that. The
ESS has been installed in the MR tunnel and will be ready for the
next slow extraction operation.
The J-PARC accelerator facilities resumed beam operation from
the linac on October 2 as scheduled. After beam tuning and study of
the accelerators, the user operation in the new period is expected to
start at the middle of October for the neutrino facility and for the
materials and life science experimental facility (MLF).
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3. [Particle and Nuclear Physics Division] by K. OZAWA, T. ISHIDA,
S. MIHARA, T. MIBE, AND T. KOMATSUBARA
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ACTIVITIES OF HADRON EXPERIMENTAL FACILITY IN THIS SUMMER
(by K. OZAWA)
Rearrangements of experimental setups and construction works for
a new beam line were performed in this summer.
An experiment to study properties of double-strangeness nuclei
was carried out before the summer shutdown and the assigned beam time
of the experiment was successfully finished. During the maintenance
period this summer, rearrangement of the experimental area at the
K1.8 beamline was performed to prepare a next experiment. The next
experiment aims to study baryon-baryon scattering using strangeness
baryons.
A new beamline to provide primary 30 GeV protons is under
construction in the transport tunnel (Switch Yard) and the south area
of the Hadron Experimental Facility. In this summer, additional
radiation shields were placed and part of the vacuum pipes was
connected in the Switch Yard. In the Hadron Experimental Facility,
the construction of a beamline dump for the primary proton beam was
finished, and concrete shield walls for the COMET beamline were
built. The construction works for the new beamline made progress step
by step.
BEAM WINDOW REPLACEMENT AND NEUTRINO BEAM INSTRUMENTATION WORKSHOP
(by T. ISHIDA)
After the successful neutrino beam production until April,
various scheduled summer maintenance works were carried out at the
neutrino experimental facility. One of the biggest tasks was beam
window replacement. The beam window separates the target station
helium vessel and primary beamline vacuum, and it must endure extreme
heating and resulting thermal stresses from penetration of intense
proton beam. The first beam window made of Titanium alloy was in
operation continuously after installation in 2008. After the
unprecedented proton beam exposure which all the atoms in the beam
spot experience nuclear reactions and displacement a few times,
significant loss of ductility was expected due to radiation damage.
To perform the replacement work in full remote operation, a 9 meter
tall special handling machine to remove the irradiated beam window
and to install a new one was developed. The sealing to the target
station vessel and the upstream monitor stack is achieved using
remotely-controllable inflatable bellows, so called "pillow" seals.
All these systems were operated successfully, and the replacement
work was completed in August. The beam operation will resume in the
middle of October, just after the next T2K collaboration meeting at
Tokai.
The 10th international workshop on neutrino beams and
instrumentation (NBI2017) was held at Tokai-mura village from
September 18 to 22, 2017.
This workshop series was initiated at KEK in 1999. It has rotated
among KEK/J-PARC, CERN, and Fermilab every two years since then,
giving unique opportunities for meeting together to physicists and
engineers working on high-intensity neutrino beam facilities and
sharing mutual knowledge, operational experience, and upgrade plans
to realize Mega-Watt-class beam power facilities. This time NBI2017
was jointly organized with the meeting of the RaDIATE collaboration,
Radiation Damage In Accelerator Target Environments, to better
understand and predict the radiation response of materials utilized
in target, beam window, and other beam intercepting applications. 56
participants, including 29 from foreign institutions, joined and 75
contributions were reported through the workshop. For more details,
visit the website: http://www-conf.kek.jp/NBI2017
STATUS OF 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 collaboration is intensively preparing
detectors towards the start of the experiment along with construction
of the facility to provide a dedicated pulsed muon beam for the
experiment. The experiment uses a long chain of superconducting
solenoid magnets to capture pions, transport muons (pions decay to
muons and neutrinos while being transported), and analyze electrons
from muonic atoms. Those solenoid magnets will be cooled down to
liquid helium temperature efficiently using two-phase helium flow.
For this purpose, the refrigerator used in E36 experiment was moved
to the COMET experiment area for reuse.
An initial cooling test of the refrigerator was conducted in
August, and it resulted in achieving the cooling power of 115W.
This is sufficient to use in COMET Phase-I. Further detailed
performance test is planned in October 2017. The COMET group had a
collaboration meeting at the end of September 2017 in Dresden,
Germany. 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 reviews in Nov. 2016 and
the 24th meeting of the program advisory committee on particle and
nuclear physics experiments.
New data on the muonium production yield from laser-ablated
silica aerogel were successfully collected in June-July at TRIUMF.
Preliminary analysis indicated good polarization in vacuum and long-
term stability of the yield.
The first test of muon acceleration with Radio Frequency
Quadrupole (RFQ) is scheduled for November, 2017 at the Materials and
Life Science Experimental Facility (MLF). Towards this test, assembly
of a vacuum chamber for low-energy muon production with acceleration
electrodes, an RFQ, and beam diagnostic apparatus were successfully
completed. A Spiral injection Test Experiment (STE) for demonstration
of three-dimensional spiral beam injection to a solenoidal magnetic
field is ongoing in Tsukuba campus. Images of injected electron beam
trajectories were successfully observed.
Evaluation of the silicon strip sensor, an improved design of the
readout Application Specific Integrated Circuit (ASIC), and
development of data acquisition (DAQ) system for the positron
tracking detector are ongoing.
PROGRAM ADVISORY COMMITTEE MEETING (by T. KOMATSUBARA)
The 24th Program Advisory Committee (PAC) meeting was held at
Tokai on July 24-26. Status of the experiments was reported, and
proposals and near-term machine time allocation were discussed.
https://kds.kek.jp/indico/event/25037/
PAC report is 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 January 15-17, 2018.
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4. [Materials and Life Science Division] by Toshiji KANAYA
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VARIOUS MAINTENANCE WORK OF NEUTRON SOURCE COMPONENTS WAS COMPLETED
NEW NEUTRON PRODUCTION TARGET VESSEL WILL BE READY TO USE AFTER
REPLACEMENT
1) Neutron Source
Various maintenance work and overhauls planned for the summer
shut-down period have been carried out as scheduled. The highlights
are as follows: 1) The proton beam window #2 was replaced with a new
one after three years of use at 2500 MWh irradiation. Highly
activated proton beam window, which was mounted on a 3.8 m long iron
plug, was lifted up into a shielding cask on the top of the neutron
source station and was moved to the irradiated component room. The
replacement was done with remote handling tools. 2) The off-gas
process system to collect gaseous radioactive materials which are
generated in the target was improved so that processing of both
collected radioactive gas and exhaust gas stored in the gas holders
through the stack can be done in parallel. This is the second step
update to shorten the target vessel replacement time from 32 workdays
to 23 workdays after the addition of gas holders last March.
From October 2, replacement of the target vessel with improved
water shroud structure will be performed. With the new target vessel,
we are going to operate the target with power of 300 to 500 kW in the
operating period from autumn to next summer.
PROPOSALS FOR 2017B PERIOD WERE REVIEWED
REPORT MEETING OF INDUSTRIAL APPLICATION WAS HELD
2) Neutron Instruments and Science
General proposals and new user promotion proposals for the 2017B
period, and long-term proposals were reviewed by the Neutron Science
Proposal Review Committee on August 31. The total number of submitted
neutron proposals was 315 (the general proposals: 286, the new users
proposals: 5, long-term proposals: 24). Finally, 167 general
proposals, five new user promotion proposals and eight long term
proposals were approved by the Materials and Life Science
Experimental Facility (MLF) Advisory Board on September 6. The total
competition rate (number of submitted / approved proposals) became as
high as 1.7 for the general proposals and 3.0 for the long-term
proposals. All of five new user promotion proposals were approved.
In this summer shutdown period, construction of BL23 (POLANO) is
in progress. Maintenance and upgrade works for existing instruments
are also carried out. For example, maintenance for the beam-transport
sections of BL01 (4SEASONS) and BL19 (TAKUMI) have been done. A long-
term running test on newly developed T0 chopper has been started.
A report meeting of industrial application at J-PARC MLF was
held on July 20 and July 21 at Akihabara Convention Center. Total
number of attendees was 452 during the two days of this meeting. The
promotion of industrial application is one of the main missions of
MLF. The industrial application at MLF is growing but it is not
steady in terms of "creation of Innovation" through the industrial
application of neutron and muon experiments. In this report meeting,
it aimed to get common understanding of the essential output on the
innovation and requiring actions by MLF for results between
industrial users and facility staff.
CONSTRUCTION OF ELECTRIC POWER SUBSTATION FOR H-LINE IS IN PROGRESS
3) Muon Science Facility (MUSE)
While neutron users are enjoying a variety of fully-fledged
beamlines and instruments in MLF, the part of muon users who are
interested in fundamental physics experiments, in particular, is
still waiting for the construction of the promised new beamline "H-line" in
experimental hall No. 1. The beamline was named after "high-momentum"
muon beam which was envisaged to deliver in the original plan. Since
then, the plan underwent significant revisions to meet demands from
proposed experiments that required high muon flux as well as momentum
tunability. The detailed design of the beamline also made it clearer
that the electric power needed to drive the beamline magnets would
exceed the current capacity in supply from MLF. The issue has now
being taken up by constructing a new electric power substation near
the MLF building. As a first step, installation of cable racks and
pitting of building wall have started during this summer shutdown
period. The construction work that includes a part of outdoor
structures will be continued until the end of this fiscal year.
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5. [Nuclear Transmutation Division] by Hayanori Takei
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SCOOPING UP THE 10 W BEAM FROM 250 KW PROTON STREAM (3)
In the last issue of the J-PARC Newsletter #64, we described a
laser charge exchange method (LCE) for the Transmutation Physics
Experimental Facility, TEF-P. This LCE method is a meticulous low
power beam extraction method from the high-power proton beam stream
of the J-PARC linac. The LCE device consists of a bright Yttrium
Aluminum Garnet (YAG)-laser and laser transport system with beam
position controllers. The negative proton (H-) beam from the J-PARC
linac is exposed to the YAG-laser beam, which can strip one of the
two electrons, so as to change H- to neutral ones (H0). The other
electron of the H0 is finally stripped by a carbon foil so that the
positive protons (H+) are introduced into TEF-P.
We installed the LCE device at the end of the 3-MeV linac in
cooperation with J-PARC accelerator division. To measure the power
and stability of the charge-exchanged H+ beam, a LCE experiment was
conducted using the 3-MeV linac. As a result of the experiment, a
charge-exchanged H+ beam with a power of 0.0359 W was obtained. If
the laser light from this LCE device collided with the H- beam (400
MeV, 250 kW) delivered from the J-PARC linac, the stripped H+ beam
with a power of 7.99}0.22 W equivalent was obtained, and this value
almost satisfies the power requirement (less than 10W) of the proton
beam for the TEF-P. This experimental result was announced at the
2017 International Beam Instrumentation Conference (IBIC 17) held in
Michigan (USA) on August 23.
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6. [Safety Division] by Yukihiro MIYAMOTO and Kotaro BESSHO
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FY2017 MEETING OF THE LIAISON COMMITTEE ON SAFETY AND HEALTH FOR
CONTRACTORS WORKING AT J-PARC
Aiming to share safety-consciousness and ensure safety with the
contractors, the J-PARC Center has been holding a liaison meeting on
safety and health for contractors annually. This year's committee
meeting was held on July 7 and had 70 participants from 66 companies.
Kotaro Bessho, Deputy Head of Safety Division, and Tetsuro Ishii,
Deputy Director (Safety), gave reports on some troubles and near miss
accidents in recent years. They also discussed that J-PARC is
encouraging workers to share and praise good safety activities.
Furthermore, as a response to the requests from the contractors,
which were to improve climate control of the working area and
protective equipment for maintenance works, responsible personnel
from each facility suggested ideas for improvement.
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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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