[Neutron] J-PARC Newsletter No. 64
shibata.kaoru
shibata.kaoru at jaea.go.jp
Tue Nov 15 05:14:33 CET 2016
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J-PARC Project Newsletter
No.64, October 2016
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]
J-PARC IS BACK ONLINE AFTER THE SUMMER/AUTUMN SHUTDOWN.
2. [Accelerator Division]
MAINTENANCE AND IMPROVEMENT WORK DURING THE SUMMER SHUTDOWN.
3. [Particle and Nuclear Physics Division]
NEW INSIGHT ON K-PP BOUND STATE.
R & D FOR NEUTRINO BEAM LINE AND T2K.
STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET) (E21).
STATUS OF THE MUON G-2/EDM (E34).
PROGRAM ADVISORY COMMITTEE MEETING.
4. [Materials and Life Science Division]
COMPONENTS OF HELIUM REFRIGERATOR WERE OVERHAULED TO RECOVER ITS
PERFORMANCE.
NINETY NEUTRON PROPOSALS WERE APPROVED FOR THE 2016B PERIOD.
MAINTENACE & CONSTRUCTION OF INSTRUMENTS ARE ONGOING.
MAKING THE RAD-HARD BASE OF S/H-LINES.
5. [Nuclear Transmutation Division]
SCOOPING UP A 10 W BEAM FROM 250 KW PROTON STREAM (2).
6. [Safety Division]
THE APPLICATION FOR LICENSES OF THE OPERATION WAS GRANTED.
THE SECOND MEETING OF THE LIAISON COMMITTEE ON SAFETY AND HEALTH FOR
CONTRACTORS WORKING AT J-PARC.
7. [Information System Section]
COMPUTING SYSTEM FOR PHYSICS ANALYSIS WAS UPGRADED.
8. [Editorial Note]
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1. [Overview] by Naohito SAITO
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J-PARC IS BACK ONLINE AFTER THE SUMMER/AUTUMN SHUTDOWN
All J-PARC facilities are back now after the relatively long
shutdown during the summer and autumn. Since the beginning of
October, the accelerator facilities resumed its operation gradually,
then the neutrino facilities started at the end of October, now the
Materials and Life Science Experimental Facility (MLF) is fully
operational. There were some minor struggles in starting some
facilities, but those were immediately solved by the teamwork of
J-PARC and relevant groups. Now we have all facilities online to
produce more exciting results.
One of the major shutdown works was the recovery of the
performance of the helium refrigerator for the neutron source at MLF.
Details are described in the MLF section in this newsletter; the
recovery work was successful and we are now back to normal operation
mode, in contrast to the last half year when we had to suspend
operation for a week every three weeks. While we had to reduce the
beam power from 200 kW to 150 kW at MLF to prolong the lifetime of
the current target system until the next summer, when the new target
will be ready for installation, we hope that users will enjoy the
beam time to produce more results.
Even during the shutdown, science is moving ahead. There were a
couple of major press releases during the shutdown. One of them is on
the neutrino program. The international T2K Collaboration announced
their first results on the CP violation search.
(http://j-parc.jp/en/topics/2016/Press160808.html)
The release reads "T2K's observed electron antineutrino appearance
event rate is lower than what would be expected based on the electron
neutrino appearance event rate, assuming that CP symmetry is
conserved."
It is certainly an encouraging result for a future discovery and we
hope that current beam time will add more significance to this
profound result!
In the end, I would like to report on the cooperation with
universities and industries. As was reported in the previous
newsletter, a J-PARC branch was established by Osaka University last
March. In April, Ibaraki University has created a new graduate course
for quantum beam science, which includes lectures and lab-course of
J-PARC/MLF. More universities are preparing their branches at J-PARC
for deeper cooperation on the research and education. In addition, we
have been preparing for a fellowship with an industry to boost the
cooperation between J-PARC and industries. We hope to expand our
cooperation with universities, institutes, and industries so that
J-PARC can be fully and deeply utilized by the users for more output
on science and technology and for fostering the next generations.
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2. [Accelerator Division] by Kazuo HASEGAWA
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MAINTENANCE AND IMPROVEMENT WORK DURING THE SUMMER SHUTDOWN
Beam operation was suspended for maintenance during the summer
shutdown from July to September. Maintenance of the components and
various improvements were made in the accelerator facilities.
The linac was mostly responsible for the downtime during
operation days. To mitigate this situation, we have taken many
countermeasures. One example is cooling water flow decrease events in
the accelerating cavities. We have flushed clogging of quadrupole
magnet cooling water channels, and we have improved the cooling water
system. The previous system had one pump to drive two main flows and
it was not easy to balance the flow. Therefore we have installed
another pump to divide into two main flow channels to ease the flow
balance control. Another example is the high power radio frequency
components. We are using twenty 324-MHz klystrons and most of the
operation time is roughly 50,000 hours. As preventive measures, we
have replaced two klystrons which have shown reduced performance.
Also we have replaced old bias power supply modules, which have been
operated for nearly 10 years and occasionally break down these days.
At the 3 GeV Rapid Cycling Synchrotron (RCS), we have replaced
a temporarily installed beam duct with a new collimator at the vacuum
leakage in April. The collimator has iron shielding slabs to reduce
residual radioactivity in its vicinity, but it has no movable
collimation functions, which is expected in next summer. We have
taken treated the extraction kicker magnets by baking to improve the
vacuum pressure and to reduce the beam loss as would be expected.
In this summer, unusually, we have had many typhoons. The rain leaks
through the roof of the power supply room. We have applied a
waterproof treatment to the roof and it has successfully made the
beam operation in October.
In the Main Ring synchrotron (MR), we have a plan to have a
higher repetition frequency operation for a power upgrade in the fast
extraction mode. One major task is the replacement of high
impedance metal magnetic alloy cores (FT3L). We scheduled a
three-year replacement, and we replaced the last 4 cavities in this
summer. All the cavities are now high impedance ones, and the
accelerating voltage is nearly double that of the original
configuration. We have replaced an injection septum magnet and a
power supply for higher repetition operation. Also we have installed
a first unit of the main magnet power supply for one of the
quadrupole magnet families. The results show good performance in
terms of lower current ripple.
The J-PARC accelerator facilities resumed beam operation on
October 3 as scheduled. After beam tuning and study of the
accelerator facilities, user operation in the new period is expected
to start at the end of October for the neutrino experiments, and at
the beginning of November for the materials and life science
experimental facility (MLF), respectively.
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3. [Particle and Nuclear Physics Division] by Y. SADA, T. TSUKAMOTO,
S. MIHARA, T. MIBE AND T. KOMATSUBARA
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NEW INSIGHT ON K-PP BOUND STATE (by Y. SADA)
A Kaonic nuclear state is an exotic state which is a meson and
baryons bound state generated by the strong interaction. K-pp, the
bound state of anti-kaon (K-) and two protons is the simplest kaonic
nuclear state and attracts wide interests in nuclear physics studies,
since it provides fundamental information of meson-baryon
interactions. Such meson-baryon interactions become important in high
density matter, such as a compact star. Many theorists predict
existence of the K-pp bound state, and several experiments are
performed to search the K-pp in the world.
Our experiment, J-PARC E15, searched for the K-pp state by using
1.0 GeV/c kaon beam and helium-3 target. We detect forward emitted
neutron and calculate a missing mass to search for a bound state.
Also, a Lambda baryon and proton emitted from the bound state are
detected to identify the state, simultaneously.
We found a peak structure in Lambda proton invariant mass
spectra which can’t be explained by known processes. The peak
structure shows a binding energy of 20 MeV and width of 110 MeV/c^2
as a K-pp bound state. These values are consistent with a theoretical
calculation. The result is published in the following web page.
http://ptep.oxfordjournals.org/content/2016/5/051D01.abstract
Now we are analyzing new data accumulated in November and
December, 2015. Its statistics are 30 times larger than the current
data and we can have conclusive results soon.
R & D FOR NEUTRINO BEAM LINE AND T2K (by T. TSUKAMOTO)
Several conferences/workshops were held in the summer. As
reported in the previous issue (J-PARC Newsletter No. 63), T2K
presented the first CP violation search result at the international
conferences, NEUTRINO 2016 (http://neutrino2016.iopconfs.org/home )
and ICHEP2016 (http://www.ichep2016.org/). Not only such physics
results but also R & D for future plans were presented at NuFact 2016
(http://vietnam.in2p3.fr/2016/nufact/) and JPS (The Physical Society
of Japan) meeting (particle physics (experiment)
https://kds.kek.jp/indico/event/22451/ in Japanese).
The design goal of J-PARC neutrino beam line is 750 kW
operation. The accelerator group and the neutrino beam line group
are not only working for it but also doing R & D to achieve mega-Watt
neutrino beam operation. There are many R & D items of neutrino beam
such as Wire Secondary Emission Monitor (WSEM), Beam Induced
Fluorescence Monitor, upgrade of target, beam window and horn,
neutrino beam line Data Acquisition (DAQ) etc. for high power with
high repetition rate.
T2K collaboration is discussing about the upgrade of near
detector ND280 for reduction of systematic uncertainty to enhance the
sensitivity toward the T2K-II phase. They are working hard to prepare
the document describing the preferred ND280 upgrade.
Maintenance in summer was carried out without problems. The
neutrino beam line and T2K near detector will be ready for the
neutrino beam start-up from Oct. 28.
STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET) (E21)
(by S. MIHARA)
The COMET experiment aims to search for the lepton-flavor
violating muon reaction, mu-e conversion, with a sensitivity better
than 10^{-14} in Phase I. In July 2016, the collaboration successfully
completed construction of the main physics detector to measure the
signal electron momentum, the Cylindrical Drift Chamber (CDC)
detector. A Cerium doped Lutetium Yttrium Orthosilicate (LYSO)
calorimeter is in progress in parallel with development of beam
measurement detector system composed of straw-tube tracker station.
In JFY 2016, tests of the CDC using cosmic rays and the beam
measurement detector system using an electron beam with 105 MeV are
planned for further advancement of the experiment.
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.
Preparations for muon acceleration test and a high-rate positron
tracking detector are in progress by the collaboration. An improved
technology to produce laser-ablated silica aerogel for the muonium
production material was developed in Canada. The first attempt to
inject charged particles by following three dimensional spiral
trajectory is being studied with a low-energy electron beam. The
design of the muon storage magnet was advanced by equipping an
additional coil for redundant system.
PROGRAM ADVISORY COMMITTEE MEETING (by T. KOMATSUBARA)
The 22nd Program Advisory Committee (PAC) meeting was held at
Tokai on July 27 - 29. Status of the experiments was reported, and
proposals and near-term machine time allocation were discussed.
https://kds.kek.jp/indico/event/21318/
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 11-13, 2017.
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4. [Materials and Life Science Division] by Toshiji KANAYA
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COMPONENTS OF HELIUM REFRIGERATOR WERE OVERHAULED TO RECOVER ITS
PERFORMANCE
1) Neutron Source
During the summer shutdown period, various maintenance and
overhauls were in progress at the 3-GeV proton transport facility and
the Neutron Source. The highlight of the maintenance was efforts to
recover performance of the helium refrigerator in the cryogenic
hydrogen circulation system.
We removed heat exchangers after cutting pipes around and
transported them to a factory to clean with Freon. We replaced the
cylindrical adsorber containing charcoal with a new one to initialize
its impurity removal performance. Furthermore, we overhauled all
elements of oil-separators of the compressor including replacement of
charcoal (ca. 370 kg). The performance recovery of the helium
refrigerator will be verified in a test operation scheduled in mid
October.
As for the neutron production target, the current target vessel
continues to be used because time is needed for fabrication of the
next target vessel aiming at improving robustness.
NINETY NEUTRON PROPOSALS WERE APPROVED FOR THE 2016B PERIOD
MAINTENACE & CONSTRUCTION OF INSTRUMENTS ARE ONGOING
2) Neutron Instruments and Science
The general proposals for the 2016B period were reviewed by the
Neutron Science Proposal Review Committee of the Materials and Life
Science Experimental Facility (MLF) and Proposal Evaluation Committee
of CROSS-Tokai in a joint meeting held on 28th July. The results were
approved by the MLF Advisory Committee and CROSS Selection Committee
in a meeting held on 31st August. The total number of submitted
neutron proposals was 234. Finally 90 proposals were approved. The
total competition rate (number of submitted / approved proposals) is
as high as 2.6.
The first half of the user program 2016A ended in June and the
second half will be resumed in November. During this summer
shutdown period, construction of Polarization Analysis Neutron
Spectrometer (POLANO, BL23) and maintenance of the other 20 neutron
beam lines was ongoing.
MAKING THE RAD-HARD BASE OF S/H-LINES
3) Muon Science Facility (MUSE)
The radiation shield around the muon beam exit for the H-line in
the experimental hall #1 was reinforced for 1 MW proton beam
operation in the near future. The design of additional shield takes
into account the first phase of H-line (at the experimental area, H1)
as well as the fully-fledged S-line (with four branches), so that it
would comprise a part of shields for both beamlines. More than 50
concrete and iron blocks were fabricated in JFY 2015 and delivered to
MLF in March, 2016. All these blocks were assembled from the
beginning of this July to the end of August. Although the assembling
work went on smoothly, it needed about 10 days longer than the
original schedule for completion. The renewed shield has been
submitted to regulatory agency for an inspection, which is planned in
the early November immediately after resuming the beam operation.
In the experimental hall #1, beams were provided for the
commissioning of a brand-new µSR spectrometer ARTEMIS which is
completed at the S1 area, one of 4 branches of the S-line.
Meanwhile, the other branches of the S-line and the entire H-line are
still under contemplation in stark contrast to the hall #2 where two
muon beam lines, D- and U-line are in full operation. Therefore early
completion of these beamlines is strongly awaited by the vast muon
users. In particular, some approved S1-type experiments in the field
of atomic and particle physics are waiting impatiently for beam on
the H-line.
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5. [Nuclear Transmutation Division] by Hayanori TAKEI
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SCOOPING UP A 10 W BEAM FROM 250 KW PROTON STREAM (2)
In the last issue of the J-PARC Newsletter #63, 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 high power proton beam stream of
the J-PARC linac. The LCE device consists of a bright 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 demonstrate the
charge exchange of the H-, a preliminary LCE experiment was conducted
after the commissioning of the 3-MeV linac. As a result of the
experiment, a charge-exchanged H+ beam with a power of 0.026W 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 about 5 W would be obtained, and
this value almost satisfied the power requirement (less than 10 W) of
the proton beam for the TEF-P.
In this experiment, we focused on the power of the stripped H+
beam. We will conduct a further experiment to confirm the beam
quality of the laser and the H-, as well as the long-term power
stability of the stripped H+ beam.
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6. [Safety Division] by Yukihiro MIYAMOTO and Kotaro BESSHO
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THE APPLICATION FOR LICENSES OF THE OPERATION WAS GRANTED
The application for licenses for the operation of the whole
facility was granted by the Nuclear Regulation Authority (NRA) on
Sep. 27. The main topics were a change of the shielding configuration
for a new muon beam line construction in the Materials and Life
Science Experimental Facility (MLF), and a change of the shielding
configuration between the switch yard and the experimental hall of
Hadron Experimental Facility (HD) for preparation of a new primary
beam line.
THE SECOND MEETING OF THE LIAISON COMMITTEE ON SAFETY AND HEALTH
FOR CONTRACTORS WORKING AT J-PARC
Liaison committee meetings started last year to share a common
safety mindset and information concerning safe work for J-PARC staff
members and contractors in J-PARC. The 2nd meeting of the committee
was held on July 6 with 74 participants from 66 companies. Tetsuro
Ishii, Deputy Director provided an overview of J-PARC and introduced
recent research topics. Then he reported on recent troubles at
J-PARC, gave precautions for work, and explained a new effort, the
"Mindful of Others: Speak out, if you find an act of danger!"
campaign.
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7. [Information System Section] by Atsushi MANABE
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COMPUTING SYSTEM FOR PHYSICS ANALYSIS WAS UPGRADED
J-PARC does not have its own computing facility and mainly uses
the KEK central computer system of KEK Tsukuba site for physics
analysis of data taken in the J-PARC facilities. In this September,
the KEK central computer system was upgraded, so that computer
resources of 4,700 CPU cores, 4.5 Pbyte disks, and 27 Pbyte tapes are
newly assigned to J-PARC. This assignment is 3.6 times CPU, 3.8 times
Disk and 5.4 times Tape resource compared to the former system. The
new system is expected to boost experiment groups’ activities at
J-PARC.
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8. [Editorial Note]
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+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Editorial Board:
Toshifumi TSUKAMOTO (Chair): toshifumi.tsukamoto at kek.jp
Kaoru SHIBATA: shibata.kaoru@ jaea.go.jp
Takashi ITO: itou.takashi at jaea.go.jp
Dick MISCHKE (English Editor): mischke at triumf.ca
Junko BEANBLOSSOM (Secretary): beanblossom.junko at jaea.go.jp
++++++++++++++++End of Letter++++++++++++++++++++++++++++++++++++++++
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