[Neutron] J-PARC Newsletter No. 68

shibata.kaoru shibata.kaoru at jaea.go.jp
Tue Dec 12 03:11:52 CET 2017


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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 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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