[Neutron] J-PARC Newsletter No. 60

shibata.kaoru shibata.kaoru at jaea.go.jp
Fri Oct 30 05:01:18 CET 2015


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     J-PARC Project Newsletter
                                                     No.60, October 2015
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 PRIMED FOR MORE SCIENCE AND USER COMFORT.

2. [Accelerator Division]
 
 MAINTENANCE AND IMPROVEMENT WORK DURING SUMMER SHUTDOWN.

3. [Particle and Nuclear Physics Division]

 BEAM TIME AND MAINTENANCE WORKS AT HADRON HALL.
 FIRST LOOK AT ANTINEUTRINO APPEARANCE FROM T2K. 

4. [Materials and Life Science Division]

 MERCURY TARGET VESSEL HAS BEEN REPLACED.
 CKORJ-PARC AND J-PARC HOSTED THE 1ST JAPAN-KOREAN JOINT WORKSHOP. 
 CONSTRUCTION OF A NEW INSTRUMENT AND MAINTENANCE FOR EXISTING 
INSTRUMENTS.
 BRAND-NEW SOLENOID AND SCRAPER ARE IN PLACE.
 CONCLUDED ARRANGEMENT ON COOPERATION WITH THE AUSTRALIAN NUCLEAR 
SCIENCE AND TECHNOLOGY ORGANIZATION (ANSTO).

5. [Nuclear Transmutation Division]

 NATIONAL REVIEW WORKING PARTY ENDORSED RESEARCH ACTIVITIES FOR 
PARTITIONING AND TRANSMUTATION.

6. [Safety Division]
 
 THE FIRST 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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 J-PARC PRIMED FOR MORE SCIENCE AND USER COMFORT

     We are very happy to begin this message with congratulations to 
Prof. Takaaki Kajita of University of Tokyo, who will be awarded the 
Nobel Prize in physics together with Prof. Arthur B. McDonald of 
Queen's University. This moment has been hoped for by many 
collaborators and relevant people including us. We are proud of 
ourselves for carrying out the T2K experiment at J-PARC, the precision 
measurements of neutrino oscillations which are the subject of the 
award. We will continue our efforts to provide more beam power and 
more protons onto the T2K target to solidify a hint for CP violation 
in the neutrino sector.
     
     Our summer was very busy as usual for maintenance and 
improvement work in all facilities. A major challenge was the 
replacement of the mercury target at MLF, which had a minor water leak 
from the protection layer surrounding the mercury vessel. As reported 
in the previous newsletter, the problem led to two months of beam time 
loss. 

     We have formed a dedicated review committee for the target vessel 
issues comprising experts external to J-PARC. Our investigation of the 
causes of the leak and preventive measures were evaluated and endorsed 
by the committee. In addition, we have received many useful 
suggestions for upcoming replacements. We are very grateful to the 
committee members for their dedicated work even with a short notice. 

     As for the lost beam time for users at the MLF, we decided to 
provide the beam to all users based on the 2015A proposal evaluations. 
Consequently, we will not call for proposals in the period of 2015B, 
while emergency proposals are always accepted as in the past. We will 
continue to operate the facility with special care for stable and 
reliable operation, balancing the beam power upgrade and careful 
inspection of target health. We aim to achieve more than 90% 
beam availability, which was achieved in the past with lower beam 
power. We are also open to any suggestions from users so that we can 
provide more convenient and comfortable research environment to the 
users. 

     There were many other work activities during the summer shutdown 
period, including the neutrino facility, hadron facility, and 
accelerator facilities. Those are covered in the following articles.  
We also worked hard on the budget negotiations with MEXT through KEK 
and JAEA, and we hope to hear better news towards the end of the 
calendar year.  

     In the end of this message, we announce the start of a series of 
workshops, "J-PARC workshop", especially to stimulate more scientific 
discussions under the J-PARC organization. There are already several 
proposals for interesting topics of science. We hope that various 
scientific outputs would emerge from the discussions in and after the 
workshops. 


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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 made in the accelerator facilities.

     At the linac, some multipacting regions, where the radio 
frequency (RF) reflection is rather high, are observed at some of the 
separated type drift tube linac (SDTL) cavities after the great 
earthquake in 2011. In particular, the region of the SDTL5#B cavity 
has been shifted to the operation point. We attempted vacuum property 
improvement by degassing with warm water, etc., but they were not so 
effective. In this maintenance period, we took more active measures 
such as cleaning of the inside of the cavity with a cloth that was 
dipped with an organic solvent. A certain improvement of the RF 
characteristics is observed so far at the high-power conditioning and 
beam tuning. 

     At the 3 GeV Rapid Cycling Synchrotron (RCS), we have several 
items for improvement. One is to reinforce the Anode power supplies 
for the acceleration cavity system. The cause of the insufficient 
power supply capacity was revealed at the 1 MW trial study. This 
improvement will lead to more stable acceleration at the higher power 
beam operation. Another is to improve the power supplies of the 
horizontal shift bump magnets. This will be expected to improve the 
flatness of the bump magnetic fields and less beam loss during beam 
injection.

     In the Main Ring synchrotron (MR), we have a plan to have a 
double accelerating voltage with approximately 1 second period for 
the fast extraction. A high impedance metal magnetic alloy core 
(FT3L) which has been newly developed is used for it. 
In 2014, one prototype cavity was installed and has already been used 
for user operation. Based on the operational results, we have made a 
plan to replace 8 existing cavities in 2015 and 2016. In this summer, 
we finished replacement of 4 of those cavities as scheduled.
We have studied and tested a shortening of the acceleration period at 
the slow extraction for the hadron experiment facility. As a result, 
it will be feasible to reduce the period from 6 seconds to 5.52 
seconds. 

     The J-PARC accelerator facilities resumed beam operation on 
September 29 as scheduled. After beam tuning and study of the 
accelerator facilities, the user operation with the new period is 
expected to start from middle of October 2015.


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3. [Particle and Nuclear Physics Division] by T. HASHIMOTO, 
K. AOKI AND T. TSUKAMOTO
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 BEAM TIME AND MAINTENANCE WORKS AT HADRON HALL (by T. TAKAHASHI and 
K. AOKI)

     Slow extraction (SX) beam was delivered for user operation 
during April 24 to May 7 and June 5 to July 1. In the beam time, 
several experiments were executed after the Hadron Hall renovations. 
Measurement of neutral Kaon rare decays was successfully resumed. A 
new experiment for testing muon-electron universality was started in 
good shape.
     In addition, an experiment to study energy levels of hypernuclei 
by precise measurement of gamma-rays was successfully carried out. 
Gamma-rays from 4-Lambda-He and 19-Lambda-F hypernuclei were measured 
by a Ge-array detector, which is called Hyperball-J. The results were 
reported at the HYP2015 conference. It is one of the major conferences 
in this field and was held at Sendai in September (http://lambda.phys.
tohoku.ac.jp/hyp2015).
     During the summer shutdown, maintenance work in the hadron 
primary beam line room was performed for the vacuum system of the 
beam line and the cooling water line of the beam dump. In addition, 
the emergency collection system was improved and no longer requires 
frequent repumping during the beam operation. Thermo-switches were 
installed to the beam dump and implemented as Machine Protection 
System (MPS).
     Before and after the maintenance work, the double layer gas-tight 
sheets, which cover the primary beam line room, were successfully 
removed and restored. They passed the airtight test and are ready to 
accept the beam.

 FIRST LOOK AT ANTINEUTRINO APPEARANCE FROM T2K (by T. TSUKAMOTO)

     The T2K collaboration observed 3 candidate electron antineutrino 
events in the muon antineutrino beam from J-PARC at Super-Kamiokande.
http://www2.kek.jp/ipns/articles/t2k-antinue-first-result/index.html
http://t2k-experiment.org/2015/07/first-look-at-antineutrino-
appearance-from-t2k/
     As reported in the last newsletter issue No.59, T2K started 
antineutrino beam operation from May 2014 and accumulated about 
4x10^20 POT (protons on target) so far, and released its first 
measurement of muon-antineutrino disappearance in May. The result of 
appearance of electron antineutrino was obtained with the same 
antineutrino beam data set. T2K would expect to observe 3.8 events, 
with 1.8 coming from backgrounds and 3 events were observed.
The search for electron antineutrino appearance with more antineutrino 
beam data is the next step in the exploration of charge-parity (CP) 
symmetry.
The result was presented at several international conferences etc. The 
details are as follows:
https://indico.cern.ch/event/356420/session/10/contribution/322
https://www2.kek.jp/physics-seminar/files2015/20150724_T2K.pdf
https://indico.fnal.gov/getFile.py/access?contribId=60&sessionId=17&
resId=0&materialId=slides&confId=9771
http://theory.fnal.gov/jetp/
http://www-conf.slac.stanford.edu/ssi/2015/
http://www.icas.ru/english/index.htm
https://indico.cern.ch/event/344173/


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4. [Materials and Life Science Division] by Toshiji KANAYA
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 MERCURY TARGET VESSEL HAS BEEN REPLACED

 1) Neutron Source
     In July, we concluded the cause of the trouble on the target 
vessel as follows. A part of the welded surface between two steel 
plates which were used to form a shroud of the target vessel for the 
cooling channel was incomplete in the fabrication process, and then a 
crack occurred with repetitive thermal stress induced by beam trips 
during the operating period. As a countermeasure against this defect, 
we changed the welding method for the shroud of a spare target vessel. 
The fabrication of the spare target vessel was completed in September 
2015. We replaced the target vessel with new one from late September 
to October 7.
     Regular maintenance from the spallation neutron source components 
to the 3-GeV proton beam transport facility was done. Periodic 
inspection and an overhaul of a hydrogen pump were conducted for the 
cryogenic hydrogen system. Survey and alignment of the 3-GeV proton 
beam transport components were also carried out.
     Pressure wave mitigation technology by using microbubbles, which 
had been developed for improving the performance of the mercury 
spallation target at J-PARC won the 2014 Japan Society of Mechanical 
Engineers (JSME) Medal for New Technology, and the mercury target 
vessel was displayed at the exhibition booth of the National Museum of 
Nature and Science from July 28 to August 10, 2015.

 CKORJ-PARC AND J-PARC HOSTED THE 1ST JAPAN-KOREAN JOINT WORKSHOP
 CONSTRUCTION OF A NEW INSTRUMENT AND MAINTENANCE FOR EXISTING 
INSTRUMENTS

 2) Neutron Instruments and Science
     The 1st Japan-Korean Joint Workshop on Polarized Neutron 
Reflectometry was held at J-PARC on July 30, 2015. It was organized 
by the Center for Korean J-PARC Users (CKorJ-PARC) and MLF. 18 
participants (Japan: 11, Korea: 7) joined this workshop. In the 
workshop, both Korea Atomic Energy Research Institute (KAERI) and 
J-PARC sides reported the current status of neutron reflectometers and 
development work on neutron optical devices including polarizing 
supermirrors and He-3 polarizing filters. Also, extensive discussion 
on future collaboration between Korea and Japan was held. The workshop 
provided a good opportunity for information exchange on this field, 
and hence CKorJ-PARC and J-PARC center agreed to enhance collaboration 
continuously.

     In this summer shutdown period, construction work of BL23 
(POLANO, Polarized Neutron Spectrometer) was carried out. The beam-
transport section and a slow chopper are being installed and tested. 
The existing instruments and auxiliary devices (choppers, optical 
devices and vacuum pumps, etc.) are being maintained and upgraded. 
Additional Si111 analyzer banks of BL02 (DNA, near-backscattering 
spectrometer) have been installed.

 BRAND-NEW SOLENOID AND SCRAPER ARE IN PLACE

 3) Muon Science Facility (MUSE)
     One of the major tasks for Muon staff in this summer shutdown 
period was the replacement of superconducting solenoid coils (SSC) on 
the D-line. The SSC and its cooling system were partially damaged in 
the Great East Japan Earthquake that occurred in 2011 and were 
temporally fixed for quick restoration.  Since then, Muon staff have 
been working in a stepwise fashion with the aim of the complete 
recovery of the whole system.  Following the replacement of the helium 
compressor system in last summer, they proceeded to the final step of 
replacing SSC.  In last July, the cannon-shaped gigantic cryostat 
containing old SSC (~6 m long) was pulled out from the channel on the 
wall separating the experimental hall from the M2 tunnel, and the 
brand-new SSC in an orange-colored cryostat was finally set up in the 
fixed position and connected to the cooling system.  The soundness of 
the entire system was proven by the subsequent test operation for 
cooling and magnet excitation conducted in collaboration with J-PARC 
Cryogenics Section and thus is ready for beam operation this coming 
fall. 
     Another major task was replacement of the beam scraper system on 
the primary proton beamline. The scraper, consisting of a set of 
water-cooled massive copper collimators, is placed just behind the 
muon production target to clean up the beam halo induced by scattering 
in the muon target.  
It turned out that one of the thermometers monitoring the local 
temperature was not operating properly, which led to the decision to 
replace the entire system considering the scheduled beam power 
increment towards the end of FY2015.  The replacement work was 
successfully conducted with special precaution to prevent the 
radiation hazard early in September.  The used scraper is now safely 
stored in one of the storage pits for highly radioactive instruments.

 CONCLUDED ARRANGEMENT ON COOPERATION WITH THE AUSTRALIAN NUCLEAR 
SCIENCE AND TECHNOLOGY ORGANIZATION (ANSTO)

 (4) International agreement
     The High Energy Accelerator Research Organization (KEK), the 
Japan Atomic Energy Agency (JAEA), and ANSTO concluded an arrangement 
on cooperation in the field of neutron science at Manly, Sydney, on 
20th July at the opening of the 2nd Asia-Oceania Conference on Neutron 
Scattering. 
     Dr. Adi Paterson, the CEO of ANSTO, visited J-PARC on 18th August 
and extensively discussed future cooperation with the Director of 
J-PARC Center and MLF staff.


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5. [Nuclear Transmutation Division] by Toshinobu SASA
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 NATIONAL REVIEW WORKING PARTY ENDORSED RESEARCH ACTIVITIES FOR 
PARTITIONING AND TRANSMUTATION

     In August 2015, the 8th and 9th meetings of national review 
working party were held in Tokyo. The meetings were called to review 
current research and development (R&D) activities for overall 
partitioning and transmutation technologies for accelerator-driven 
systems (ADS). 
     In the meeting, J-PARC Center introduced the latest result of 
technology development for construction of Transmutation Experimental 
Facility, specifically for the ADS Target Test Facility, TEF-T. R&D 
activities for partitioning, minor actinide bearing fuel fabrication, 
and Transmutation Physics Experimental Facility, TEF-P, were also 
presented by Partitioning and Transmutation Technology Division of 
JAEA. 
     Though official recommendation has not been issued, the working 
party expressed its recognition of the proper progress in our 
activities and had opinions to endorse the R&Ds to establish 
transmutation technologies by ADS together with the technologies for 
partitioning and handling of fuels for transmutation in the meetings. 
     From the technical point of view of the R&D for TEF-T, increasing 
operation temperature, temperature gradient of target mockup loop and 
management of oxygen potential control in flowing high temperature 
liquid metal are identified as the most pressing concerns. The 
preparation of mockup loop operation including refurbishment of the 
loop components is underway.


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6. [Safety Division] by Yukihiro MIYAMOTO and Kotaro BESSHO
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 THE FIRST MEETING OF THE LIAISON COMMITTEE ON SAFETY AND HEALTH FOR 
CONTRACTORS WORKING AT J-PARC

     The Liaison Committee on Safety and Health for Contractors 
Working at J-PARC was established in order to share a common safety 
mindset and information concerning safe work at J-PARC. The first 
meeting of the committee was held on July 24 at an exhibition hall of 
JAEA, Atom World, with 80 participants from 75 companies. At the 
meeting, there were reports on recent accidents and troubles in 
J-PARC, and also lessons learned from them and precautions were 
presented. Based on these reports, some opinions were given by 
contractors for ensuring a safe work environment. We believe that 
these reports and discussions should be helpful to raising safety 
awareness for the contractors working at J-PARC. Furthermore, the 
latest safety information on J-PARC has been continuously shared 
through e-mail after the meeting.


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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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