[Neutron] J-PARC Newsletter No.58

Mon May 4 10:18:48 CEST 2015

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     J-PARC Project Newsletter
                                                    No.58, April 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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EDITORIAL NOTE-------------------------------------------------------
     In the process of editing this newsletter, we have received two 
more important news on the operation of the Materials and Life Science 
Experimental Facility with 500 kW from April 14 and resumption of the 
operation at the Hadron Experimental Facility from April 24. More 
details will be reported in a next special issue of J-PARC newsletter.
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HEADLINES AND CONTENTS

1. [Overview]

 ACCELERATION OF A PROTON BEAM PULSE EQUIVALENT TO 1-MW WAS 
SUCCESSFULLY DEMONSTRATED. 
 THE HADRON EXPERIMENTAL FACILITY RENOVATION HAS COMPLETED.

2. [Accelerator Division]

 J-PARC ACCELERATOR DELIVERED 400-kW BEAM TO MLF USERS AND 320-KW BEAM 
TO T2K EXPERIMENT.

3. [Particle and Nuclear Physics Division]

 OBSERVATION OF A "K-PP"-LIKE STRUCTURE IN THE D(PI+, K+) REACTION.
 NEUTRINO BEAM OPERATION WITH 320 KW BEAM POWER AND ACHIEVEMENT OF 
1x10^21 PROTONS ON TARGET.
 PROGRESS IN MUON PARTICLE PHYSICS PROGRAMS.
 THE WORKSHOP "FLAVORS OF NEW PHYSICS". 

4. [Materials and Life Science Division]

 1 MW EQUIVALENT PROTON BEAM PULSE WAS DELIVERED FOR THE FIRST TIME. 
 PROTON BEAM POWER FOR USER PROGRAM WAS RAMPED UP TO 400 KW.
 168 NEUTRON PROPOSALS WERE APPROVED FOR THE 2015A PERIOD BY THE 
NEUTRON SCIENCE PROPOSAL REVIEW COMMITTEE.
 A FIRE FROM THE MUON D-LINE SEPTUM MAGNET POWER SUPPLY.

5. [Nuclear Transmutation Division]

 CHALLENGES FOR LIQUID METAL APPLICATION IN HIGH TEMEPRATURE 
CONDITION.

6. [Safety Division]

 SYMPOSIUM ON SAFETY IN ACCELERATOR FACILITY.
 J-PARC SAFETY MEASURES REINFORCED AFTER THE FIRE IN THE MATERIALS 
AND LIFE SCIENCE EXPERIMENTAL FACILITY (MLF).

7. [Information System Section]

 NEW NETWORK SEVICES "USER LAN" STARTED.

8. [Editorial Note]

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1. [Overview] by Yujiro IKEDA
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 ACCELERATION OF A PROTON BEAM PULSE EQUIVALENT TO 1-MW WAS 
SUCCESSFULLY DEMONSTRATED

 THE HADRON EXPERIMENTAL FACILITY RENOVATION HAS COMPLETED  

     A proton beam pulse was accelerated to the power equivalent of 
1-MW and injected to the mercury target. This achievement implies 
great promise to realize the stable 1-MW beam supply to users soon.

     All of the renovation to prevent a recurrence of similar 
accidents has been completed at the Hadron Experimental Facility. 

     Because of the fire of a transformer in a power supply at the 
muon area of the Materials and Life science Experimental Facility 
(MLF), J-PARC suspended all the J-PARC beam operation for a month. All 
facilities were inspected to confirm the safety. Further safety 
measures against these potential risks in normal work were implemented 
in the J-PARC safety procedures.

     The 400-kW beam operation at MLF has started right after 
restarting the user programs. At MR, proton beams at 320-kW power have 
been delivered to the neutrino experiment. Very recently, 1.0 x 10^21 
protons on target was recorded.

     Concerning the process for the full recovery from the accident at 
the Hadron Experimental Facility on May 23, 2013, we reported critical 
points, the measures for the incident, and the renewed procedures to 
strengthen safety throughout J-PARC activities, to the Governor of 
Ibaraki Prefecture, the Mayor of Tokai-village, and neighboring 
municipalities. The report has been accepted for the safety measures 
being properly implemented, and they kindly encouraged us to proceed 
toward restart of the facility operation.

     This is the final newsletter for me (Yujiro IKEDA) to report on 
J-PARC to you. By taking this opportunity, I would like to express my 
sincere gratitude to everyone: all of the J-PARC users, J-PARC staff, 
High Energy Accelerator Research Organization (KEK), Japan Atomic 
Energy Agency (JAEA), Ministry of Education, Culture, Sports, Science 
and Technology (MEXT), Tokai village, Ibaraki prefecture, and others 
for your enthusiastic support during my term as J-PARC Center 
Director. Because of your great support and understanding, we 
conquered big challenges. I hope you would like to give us your 
continuing support and cooperation in the future. 
Thank you very much.
I wish you all the best. 

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2. [Accelerator Division] by Tadashi KOSEKI
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 J-PARC ACCELERATOR DELIVERED 400-kW BEAM TO MLF USERS AND 320-KW BEAM 
TO T2K EXPERIMENT

     After the beam shutdown due to the fire at the muon facility of 
the Materials and Life Science Experimental Facility (MLF), the J-PARC 
accelerator resumed beam delivery to the T2K experiment on February 25 
and to the neutron users of the MLF on February 26. 
Before the restart of user operation for the T2K experiment, 
accelerator studies were performed in the Main Ring synchrotron (MR) 
for suppression of transverse beam instability and correction of 
betatron resonances. For suppression of the beam instability, 
parameters of two types of bunch feedback systems, patterns of rf 
voltage, and sextupole magnet field were optimized in the timings of 
beam injection and acceleration. As to correction of the resonance, 
parameters of four skew-quadrupole magnets were optimized to correct 
linear coupling resonance. As a result of these studies, the beam loss 
in the MR was reduced and the beam intensity could be raised from 260 
kW to 320 kW. The MR stably continued the beam operation with the 
320-kW beam power for the T2K experiment until the end of March. The 
number of delivered protons on the neutrino target exceeded 1x10^21 on 
March 26.  
For the MLF users, the Rapid Cycling Synchrotron (RCS) increased beam 
power from 300 kW to 400 kW on March 10. After one day of operation 
with 400 kW, residual radioactivity was measured in the linac and the 
RCS and it was confirmed that serious radioactivity was not observed 
on the accelerator components. Since then, the RCS has delivered 
stable 400 kW beam to the MLF users. The further increase of the beam 
intensity from 400 kW to 500 kW is now planned for the middle of 
April.  

     In the first week of April, accelerator studies of the linac and 
the RCS were performed for stable beam operation with higher beam 
intensity. For the MR, a newly-manufactured small kicker magnet was 
installed during one-week maintenance. The magnet, which is called 
compensation kicker can correct an extra kick of the circulating 
bunches by imperfect magnetic field pattern of the injection kicker 
system.  The compensation kicker is expected to reduce beam loss 
during beam injection and to lead an operation with a second harmonic 
rf system, which can decrease the incoherent tune shift due to space 
charge force. The second harmonic rf system is one of the key devices 
to achieve higher beam power in the MR. The beam study with the second 
harmonic rf system is planned in May.

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3. [Particle and Nuclear Physics Division] by Y. ICHIKAWA, 
T. TSUKAMOTO, S. MIHARA and T. KOMATSUBARA
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 OBSERVATION OF A "K-PP"-LIKE STRUCTURE IN THE D(PI+, K+) REACTION
(by Y. ICHIKAWA)

     Study of di-baryon systems including strangeness, such as a 
KbarNN system, is one of the most important topics in modern nuclear 
physics, since introducing a new degree of freedom in the nucleus is 
an important touchstone to understand hadron interactions based on 
Quantum Chromodynamics.

     A bound state of K-pp is predicted theoretically; however, its 
existence is not clear experimentally. Measurements of the binding 
energy and the width of the K-pp system would give fruitful 
information particularly on the Kbar-N interaction.

     We carried out the E27 experiment, at the K1.8 beam line of 
J-PARC Hadron Experimental Facility using the d(pi+, K+) reaction at 
1.69 GeV/c to investigate the K-pp system. In this reaction, a K-pp 
bound state is expected to be formed through Lambda (1405) production 
as a doorway. The key experimental technique is a coincidence of high-
momentum proton(s) at large emission angles, which enhances the 
signal-to-background ratio.

     We have measured a missing-mass spectrum in the pi+ d -> K+ + X 
reaction by requiring two protons emission in the reaction for the 
first time.  The spectrum shows "K-pp"-like structure, which can be 
interpreted as an evidence of "K-pp" bound state. The evaluated K-pp 
binding energy is 100 MeV with a large width.
Other possibilities are also discussed. The results were published in 
Progress of Theoretical and Experimental Physics (PTEP 2015, 021D01):
http://dx.doi.org/10.1093/ptep/ptv002.

 NEUTRINO BEAM OPERATION WITH 320 KW BEAM POWER AND ACHIEVEMENT OF 
1x10^21 PROTONS ON TARGET (by T. TSUKAMOTO)

     Neutrino beam line started operation on Jan. 12 but J-PARC 
accelerators stopped from Jan.16 due to the fire of a power supply at 
MLF. Neutrino beam operation was resumed from Feb. 25 and then soon 
320 kW beam power was achieved. T2K experiment continued until the 
morning of Apr.1 with anti-neutrino beam. The POT (protons on target) 
so far reached at 1x10^21 (http://t2k-experiment.org/2015/03/j-parc-
delivers-1x1021-protons-on-target-to-t2k/).
     T2K collaboration released the result of measurements of neutrino 
oscillation using data from the T2K long-baseline neutrino experiment 
collected from 2010 to 2013, which corresponds to 6.6E20 POT. This 
result was submitted to Physical Review D and http://arxiv.org/abs/
1502.01550.
     Takashi Kobayashi (KEK), Tsuyoshi Nakaya (Kyoto Univ.) and Masato 
Shiozawa (ICRR) were awarded the 6th Yoji Totsuka prize (http://www.
hfbs.or.jp/orito-totsuka-prize-index.html (only in Japanese)). The 
research theme for their award is "The observation of electron 
neutrino appearance in a muon neutrino beam". They have played a 
leading role in the T2K collaboration. Takashi Kobayashi (KEK) was 
also chosen to receive the 21st Yomiuri Techno Forum Gold Medal Prize 
(http://info.yomiuri.co.jp/event/2015/03/18.php).

 PROGRESS IN MUON PARTICLE PHYSICS PROGRAMS (by S. MIHARA) 

     The COMET experiment aims at searching for the mu-e conversion 
with a target sensitivity of 10^{-14} in Phase I. R&D of detectors to 
identify the signal electrons has been conducted intensively by the 
COMET collaboration. Facility construction at J-PARC is also in 
progress.
     In March 2015, one of the ingredients of the experiment, the muon 
transport solenoid magnet, has been installed in the experimental area. 
The solenoid magnet is to transport a high intensity muon beam from 
a pion production target located in the primary beam line. 
Conditioning of the magnet will follow in JFY 2015.
     Preparation for a precision determination of the muon magnetic 
and electric dipole moments is also in progress. The muon g-2/EDM 
group is preparing for a technical design report. Initial acceleration 
apparatus for muon acceleration R&D was assembled at MLF.

 THE WORKSHOP "FLAVORS OF NEW PHYSICS" (by T. KOMATSUBARA) 

     The Workshop "Flavors of New Physics" was held on Mar. 9 and 10, 
2015 at Tokai to discuss the potential of the new physics discoveries 
at J-PARC and other frontier facilities. This workshop is supported by 
KEK Theory Center.
http://kds.kek.jp/conferenceDisplay.py?confId=17388

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4. [Materials and Life Science Division] by Masatoshi FUTAKAWA
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 1 MW EQUIVALENT PROTON BEAM PULSE WAS DELIVERED FOR THE FIRST TIME 

 PROTON BEAM POWER FOR USER PROGRAM WAS RAMPED UP TO 400 KW

     1) Neutron Source
     On January 12, 1MW equivalent proton beam pulses were 
successfully delivered through the 3-GeV proton beam transport 
facility to the neutron production mercury target for the first time. 
A beam study was also conducted changing the power from 300 kW to 593 
kW, and the intensities of cold and thermal neutrons were verified to 
be proportional to the incident beam power.
     Neutron production for the user program was started with a proton 
beam power of 300 kW on February 26 after a month of suspension due 
to the fire in the Materials and Life Science Experimental Facility 
(MLF). The proton beam power was ramped up to 400 kW from March 10.

 168 NEUTRON PROPOSALS WERE APPROVED FOR THE 2015A PERIOD BY THE 
NEUTRON SCIENCE PROPOSAL REVIEW COMMITTEE

     2) Neutron Instruments and Science
     The general proposals for the 2015A period were reviewed by the 
Neutron Science Proposal Review Committee, and finally 168 neutron 
proposals were approved from 281 proposals by the MLF Advisory Board; 
in addition, 33 proposals were reserved. The total competition rate 
(requested / available beam time) is as high as 1.8.
     The beam operation for RUN #60 originally scheduled from January 
17 was canceled due to the fire in MLF. Parts of the beam time in RUN 
#61 were also canceled due to the troubles at RCS and with the neutron 
source. In total, 33.5 days of user beam time were lost. A number of 
users, both domestic and abroad, were affected by these troubles. The 
experiments that were canceled in RUN #60 and RUN #61 have been 
carried over into the 2015A period. As a result, the period of 2015A 
will be extended. 
     The J-PARC Center hosted the 14th Korea-Japan meeting on Neutron 
Science from January 7 to 9 at Ibaraki Quantum Beam Research Center in 
Tokai, Japan. The meeting had 29 participants from Korea and 50 from 
domestic (including Korean scientists living in Japan), and had 56 
presentations in oral sessions and a poster session. We discussed 
further collaborations from various perspectives between Korea and 
Japan in the meeting.
     Construction of a polarized neutron chopper spectrometer, POLANO 
at BL23 is in progress. A scattering chamber was delivered to the MLF 
experimental hall on January 15. We are expecting to receive the first 
neutron beam to POLANO at the beginning of JFY 2015.

 A FIRE FROM THE MUON D-LINE SEPTUM MAGNET POWER SUPPLY

     3) Muon Science Facility (MUSE)
     A fire at the Second Experimental Hall of the Materials and Life 
Science Experimental Facility, occurred at 15:01 on January 16. The 
power supply for the septum magnet at the muon D-line caught fire. To 
improve the stability of the current to the septum magnet, a newly 
fabricated transformer was added to the existing power supply. 
Electric power was turned on for the first time on January 16. In a 
few minutes, the transformer started smoking and partly on fire. 
Fortunately, the fire was immediately controlled by a hand 
extinguisher. The fire arose from a mistake in the circuit design of 
the power supply. The root causes of the incident were the 
insufficient safety check of the circuit, and the failure of the 
performance test of the whole system by the manufacturer. It was also 
pointed out that the J-PARC staff had not been fully aware of risks 
behind the power test in a radiation controlled area.

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5. [Nuclear Transmutation Division] by Toshinobu SASA
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 CHALLENGES FOR LIQUID METAL APPLICATION IN HIGH TEMEPRATURE CONDITION

     The operation of lead-bismuth eutectic (LBE) alloy for protecting 
structural materials from corrosion at a high temperature is a key 
technology to realize future accelerator-driven systems (ADS) for 
nuclear transmutation and the J-PARC ADS Target test Facility (TEF-T). 
Two sets of large-scale LBE loop equipment are in production and one 
of them is a mock-up LBE loop for TEF-T primary loop system. 
LBE is a fluid operated inside this loop in conditions of temperature 
from 250 to 500 degree centigrade. The loop has a capacity to set the 
temperature gradient of 100 degrees between hot-leg and cold-leg by 
60kW electric heater and secondary water-cooling circuit. LBE will 
circulate by electro-magnetic pump, which has the same specifications 
for TEF-T target system. A flow meter using ultrasonic waves is used 
to observe the flow rate of the LBE in the loop. A prototype of the 
spallation target for material irradiation is also set up in the loop 
to obtain a non-irradiated specimen to evaluate the irradiation 
effects in flowing LBE environment.
     The other loop is used for material corrosion studies at the 
temperature range below 550 degree centigrade. The loop is made of 316 
stainless steel except for high temperature sections made of T91, such 
as a surge tank and integrated corrosion test sections. The loop will 
be equipped with three test sections for corrosion tests at different 
temperatures and LBE flow speeds, simultaneously.
     Instruments to be needed to operate LBE loops are also under 
development. Two kinds of oxygen potential sensors using pure bismuth 
metal and platinum catalyst were fabricated. Because both sensors 
are made by fragile zirconia tube, an LBE leak-free sensor housing is 
also under development. In addition, the long-lasting ultrasonic flow 
meter for LBE with thousands of hours of operation is under 
development by collaboration with scientists for fast reactor 
developments.

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6. [Safety Division] by Tetsuro ISHII
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 SYMPOSIUM ON SAFETY IN ACCELERATOR FACILITY

     The 2nd Symposium on Safety in Accelerator Facility was held on 
March 6 at Tokai, and information on safety was shared with about 120 
participants. The J-PARC Center reported the preventive measures 
against the radioactivity leak incident in the Hadron Experimental 
Facility and the recovery from the incident.
Activities on safety in the European Organization for Nuclear Research 
(CERN) and Paul Scherrer Institute (PSI) were reported, followed by 
the report on the topics of the International Technical Safety Forum 
held on September, 2014. Safety issues as a user facility were also 
reported from Research Center for Nuclear Physics (RCNP), RIKEN, 
Spring-8, and the Materials and Life Science Experimental Facility 
(MLF) of J-PARC.

 J-PARC SAFETY MEASURES REINFORCED AFTER THE FIRE IN THE MLF

     Causes of the incident from the safety management aspect: 
1) Safety confirmation at the time of order was insufficient.
2) Risk estimation on the on-site test was insufficient.

     The J-PARC Center has established a basic framework for safety 
management and operated the facilities within the framework. However, 
this time, the risk on the on-site test was overlooked because of a 
low power device and as a result the work was "dropped off" from the 
safety inspection.
     The essential measure is to provide an adequate system to ensure 
nothing is overlooked. We established two procedures as follows:
1) J-PARC Center Work Flow Standard, which is the crucial procedure 
to ensure the safety works and stipulates the following processes at 
the time of order:
i. Oblige a contractor to provide documents/references to confirm the 
safety of equipment.
ii. Carry out safety confirmation by the J-PARC Center on the basis of 
the documents/references.
2) Provision of Safety Confirmation in Division/Section, which picks 
up high risks in the work and shares the information at regular 
meetings in each division, in view of the 3H keywords ("Hajimete"
(first time), "Henko"(modification), "Hisashiburi"(first time after a 
long interval)), to confirm safety under the responsibility of the 
division.

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7. [Information System Section] by Atsushi MANABE
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 NEW NETWORK SEVICES "USER LAN" STARTED

     Since 2009, J-PARC has offered a Guest network (GWLAN) service. 
The GWLAN is a wireless internet connection service for short-term 
visitors available in almost all J-PARC buildings. The visitors are 
requested to ask the J-PARC Users Office for a password before using 
the GWLAN. At the beginning of 2015, a new network service called User 
LAN started for J-PARC facility users. In the new service, users are 
authenticated by the same ID and password which are used in the User 
Support System for dormitory reservation and so on.
We hope the new system will contribute to improve usability of 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
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