[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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Information on the project can be also obtained at the web site:
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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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