=====================================================================
J-PARC Project Newsletter
No.57, January 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
=====================================================================
HEADLINES AND CONTENTS
1. [Overview]
RESTORATION WORK OF THE HADRON EXPERIMENTAL FACILITY PROCEEDS
STEADILY.
2. [Accelerator Division]
1-MW EQUIVALENT BEAM WAS DEMONSTRATED SUCCESSFULLY IN ACCELERATION
AND EXTRACTION.
3. [Particle and Nuclear Physics Division]
NEW RESULTS ON THE INCLUSIVE SPECTRUM MEASUREMENT OF THE D(PI+, K+)
REACTION.
PROGRAM ADVISORY COMMITTEE MEETING.
NEUTRINO BEAM LINE HAS BEEN OPERATING AND T2K HAS BEEN TAKING DATA
STABLY.
4. [Materials and Life Science Division]
THE MERCURY TARGET WAS REPLACED WITH AN ADVANCED TYPE.
PROPOSALS FOR 2015A, COMMISSIONIG FOR BL22, AND INTERIM ASSESSMENTS
FOR 5 BEAMLINES.
A NEWLY DESIGNED ROTATING GRAPHITE TARGET WAS SUCCESSFULLY INSTALLED.
5. [Nuclear Transmutation Section]
INTERNATIONAL COOPERATION FOR THE REALIZATION OF ACCELERATOR-DRIVEN
SYSTEMS.
6. [Safety Division]
THE SAFETY AUDIT.
THE SAFETY INSPECTION IN THE 50-GEV MAIN RING (MR) AND HADRON
EXPERIMENTAL FACILITY (HD).
7. [Editorial Note]
---------------------------------------------------------------------
1. [Overview] by Yujiro IKEDA
---------------------------------------------------------------------
We would like to express our sincere apology for any
inconvenience caused by the suspension of the J-PARC operation due to
the fire in the Materials and Life Science Experimental Facility (MLF)
on January 16, 2015.
Around 15:01, the fire occurred in a power supply of the Muon
experimental area of the MLF. The fire was immediately extinguished.
There were neither injuries nor leaks of radioactive materials in the
hall and into the environment.
The cause of the fire was identified to be the design error of
the modification applied to the power supply.
We have been working to develop preventive measures against
reoccurrence of similar incidents and to provide the safer
experimental environment to users.
We would deeply appreciate your understanding and continuous
support.
RESTORATION WORK OF THE HADRON EXPERIMENTAL FACILITY PROCEEDS
STEADILY
Due to the Lower House election in December the FY2015 budgetary
process is delayed. At the end of 2014, we could only tell you that
there has been officially no significant change in the budget amount
shown in the last newsletter.
Regarding our endeavor for restarting the Hadron Experimental
Facility, we reached a few milestones as follows:
1) On October 29, the 7th External Expert Panel, which has
reviewed "The radioactive material leak accident at the J-PARC Hadron
Experimental Facility", was held. It was confirmed by the panel that
efforts are being properly carried out, and that the schedule for
restarting facilities is appropriate.
2) On November 25, the emergency evacuation drill was carried
out for a situation, assuming a scenario of target damage like the
Hadron accident 2013. The drill went smoothly, showing new emergency
procedures worked properly. We are hoping to restart beam operation
at the Hadron facility within this fiscal year.
I am proud of the J-PARC accelerator team for their important
achievement of 1 MW equivalent pulse, even though it was a few shots.
Details are given by the accelerator division in this newsletter.
The Nishina Memorial Prize 2014 award goes to Takeshi Kobayashi,
Head of the Particle & Nuclear Physics Division and T. Nakaya of Kyoto
Univ. for their outstanding achievement by the T2K experiment of
discovering the phenomenon in which electron neutrinos appear from a
beam of muon neutrinos.
Outreach activities:
In order to promote rigorously exchanges with local residents for
increasing mutual understanding of our activity, J-PARC jointly
participated in an open-air market in Tokai Village, called "Ozora
Marche", for the first time and set up a "Science Experiment Corner".
Many people participated, ranging in age from children to adults, and
the event was a great success. J-PARC also provided other outreach
programs such as "Hello Science" (a science lab class) and "a public
lecture" to the local residents. These outreach activities will be
continued.
---------------------------------------------------------------------
2. [Accelerator Division] by Tadashi KOSEKI
---------------------------------------------------------------------
1-MW EQUIVALENT BEAM WAS DEMONSTRATED SUCCESSFULLY IN ACCELERATION
AND EXTRACTION
During the summer shutdown period from July to September, the
front-end system of the linac was replaced to increase the peak
current from 30 mA to 50 mA. The new front-end system consists of an
rf (radio-frequency)-driven ion source and RFQ (Radio Frequency
Quadrupole linac), which is designed to be optimized for accelerating
the 50 mA beam.
The beam operation of Linac was resumed on September 29 and
achieved 50 mA beam acceleration on October 15. The RCS and Main Ring
Synchrotron (MR) restarted beam study on October 15 and 26,
respectively. In the study period, the RCS successfully demonstrated
the beam acceleration and extraction with the intensity up to 773 kW-
equivalent (6.44x10^13 particles) in a single-shot operation mode.
However, the beam acceleration with the intensity larger than 800-kW-
equivalent could not be achieved due to insufficient current capacity
of the anode power supplies for the rf power amplifiers.
After the accelerator study, user operation was restarted for the T2K
experiment and the Materials and Life Science Experimental Facility
(MLF) users on November 2 and 4, respectively. The delivered beam
power in the operation in November and December for the T2K
experiment was 220 - 260 kW and that for the MLF users was 300 kW.
At the end of 2014, we tried high power beam acceleration in the RCS
again after the end of the user operation in December 2014. In order
to increase the RCS intensity larger than 800 kW, the resonance
frequencies of all of the twelve rf cavities were shifted from 1.7
MHz to 2.1 MHz to reduce required current in the anode power supplies.
As a result, the RCS successfully accelerated and extracted a 1-MW-
equivalent beam (8.32x10^13) in the single shot mode on the morning
of December 27. Although more study time is required to reduce beam
loss and also reinforcement of the anode power supplies of the rf
power amplifiers is necessary, the achievement of 1-MW-equivalent
beam acceleration is an important milestone for the J-PARC
accelerator.
In the MR, the first prototype power supply, which was developed
for the main magnet power supply in the near future high repetition
rate operation of 1 Hz, was manufactured and tested at a manufacturer.
The prototype power supply has a capability to output 25% of the
full scale power supply. All of the electric-circuit components have
the same specification as the ones in full scale power supply.
Therefore the prototype power supply can be modified to the full
scale power supply just by adding two or three chopper units to the
existing unit in parallel. The operation test of the prototype power
supply has been successfully done by the close collaboration with the
manufacturer. Now we are almost ready for starting mass production of
the main magnet power supply system for the high repetition rate
operation.
---------------------------------------------------------------------
3. [Particle and Nuclear Physics Division] by Y. ICHIKAWA,
T. TAKAHASHI, K. OZAWA, T. KOMATSUBARA AND T. TSUKAMOTO
---------------------------------------------------------------------
NEW RESULTS ON THE INCLUSIVE SPECTRUM MEASUREMENT OF THE D(PI+, K+)
REACTION (by Y. ICHIKAWA, T. TAKAHASHI, K. OZAWA)
Study of interactions between nucleon and hyperon, which contains
strange quark(s), attracts wide interest in nuclear physics research
field, since the Hyperon-Nucleon interactions are keys to understand
Baryon-Baryon interactions from the fundamental theory, quantum
chromodynamics (QCD). The Baryon-Baryon interactions, such as a
nuclear force, make a variety of nuclei and a variety of the elements
and they have essential roles in developments of our material world.
Several experiments are performed at J-PARC Hadron Experimental
Facility to study characteristics of Hyperon-Nucleon interactions.
One of the most useful methods to study the interactions is the
measurement of hyperon production with a nucleus. At the J-PARC E27
experiment, a pi+ beam and a deuteron target were used to produce
hyperons. The production of hyperons was identified by detecting
emitted Kaons. An inclusive missing-mass spectrum of the above
reaction at the beam momentum of 1.69 GeV/c was measured with high
statistics and high energy resolution.
Several new features were observed in the spectrum. A yield
enhancement between Lambda and Sigma peaks was observed. The
enhancement could be understood as a SigmaN cusp, which is important
to study the SigmaN-LambdaN coupling strength.
The other observation is a shift of a known broad bump structure.
We don't yet have a clear explanation of the shift. To explain the
observed puzzling "shift", further theoretical developments of the
Hyperon-Nucleon interactions will be required and also it will lead
to better understanding of fundamental materials. The results were
published in Progress of Theoretical and Experimental Physics (PTEP
2014, 101D03).
PROGRAM ADVISORY COMMITTEE MEETING (by T. KOMATSUBARA)
The 19th PAC meeting was held at Tokai during Dec. 3 - 5, 2014.
Status of experiments were reported and machine time allocation was
discussed in the meeting.
http://kds.kek.jp/conferenceDisplay.py?confId=17089
NEUTRINO BEAM LINE HAS BEEN OPERATING AND T2K HAS BEEN TAKING DATA
STABLY (by T. TSUKAMOTO)
The operation of the neutrino beam line was started from the
beginning of November and T2K took data stably until December 22.
After the operation was stopped, the accelerator maintenance and study
were carried out until December 26. It is particularly worth noting
that replaced beam line magnet power supplies and new power supply for
horns had been working without affecting beam operation efficiency.
After the shutdown in the year-end and new-year holidays, the
operation of the neutrino beam line and the T2K near detector were
resumed from January 12.
Professor T. Kobayashi (KEK) and professor T. Nakaya (Kyoto
University) were awarded the 2014 Nishina Memorial prize on
"Discovery of electron neutrino appearance from muon neutrino beam",
which has appeared on the web :
http://www.nishina-mf.or.jp/index_e.html
---------------------------------------------------------------------
4. [Materials and Life Science Division] by Masatoshi ARAI
---------------------------------------------------------------------
THE MERCURY TARGET WAS REPLACED WITH AN ADVANCED TYPE
1) Neutron Source
The mercury target vessel was replaced in October 2014 with an
advanced type, which has a double-walled structure at the top portion
of the container to make a faster mercury flow in a narrow channel.
The neutron source has been operated stably with a proton beam power
of 300 kW in the 2014A user program.
The former target vessel had been used since December 2011 and
the accumulated beam power was 2050 MWh. We cut out a specimen with a
diameter of 5 cm from the top portion of the container. No prominent
pitting damage was observed on the inner surface of the specimen.
This result indicates that the gas micro-bubbles injection functioned
well to mitigate the pitting damage from the cavitation that occurred
with the proton bombardment in the mercury.
PROPOSALS FOR 2015A, COMMISSIONIG FOR BL22, AND INTERIM ASSESSMENTS
FOR 5 BEAMLINES
2) Neutron Instruments and Science
After the summer shutdown, the user program resumed on the 4th
of November. The period of 2014B was started from the 11th of December
and will be continued to April 2015. We called the general proposals
for 2015A. The call for proposals was closed in the beginning of
November and 275 neutron proposals were submitted. Those proposals
will be sent to the Neutron Science Proposal Review Committee for
reviewing process.
An inspection on radiation shielding was carried out by Nuclear
Safety Technology Center on the 7th of November and it was approved
without any serious problems. During this process, BL22, RADEN (Pulsed
Neutron Imaging Instrument) received its first neutron beam to test
the shielding ability. After the inspection, BL22 proceeded to its
commissioning phase.
Interim assessment and reviews for the neutron instruments, which
have run for 5 years from starting the operation, are in progress by
the Neutron Instrument Proposal Review Committee. The beam
lines included are BL05, BL12, BL14, BL16 and BL21. The committee will
evaluate the performance of the instruments, and advise on the
operation in the next five-year term.
We held the 2nd MLF School from 16th to 19th of December. We had
22 participants from domestic (13), Korea (4), China (4) and Mongol
(1). They took lectures on Neutron and Muon science and enjoyed
grouped experiments using one of 7 neutron instruments or a muon
instrument.
A NEWLY DESIGNED ROTATING GRAPHITE TARGET WAS SUCCESSFULLY INSTALLED
3) Muon Science Facility (MUSE)
Since September, 2008, we have been utilizing an edge-cooled
graphite target successfully for the muon and pion production at
J-PARC MUSE. The buffer layer of the Ti interface was inserted between
the graphite and copper frame in order to release stress by
considering the degradation of the thermal conductivity by the neutron
irradiation.
However, this structure may not have enough tolerance to accept
the proton beam power planned to be upgraded to 1MW in one and a half
years. Therefore, we decided to replace the present target with a
newly designed rotating graphite target, which can accept a proton
beam with much wider area, for reducing the radiation damage. The
outer and inner diameters are 330 mm and 230 mm respectively, and the
thickness is 20 mm. It is designed to be operated at a 15-r.p.m.
rotation speed (rotation per minute) with use of WS_{2} solid
lubricant for the bearings. We expect that the lifetime can be longer
than 10 years at the 1 MW operation. We tested it and confirmed that
it had been stably operated with 300 kW proton beam without any
troubles since the beginning of November.
---------------------------------------------------------------------
5. [Nuclear Transmutation Section] by Toshinobu SASA
---------------------------------------------------------------------
INTERNATIONAL COOPERATION FOR THE REALIZATION OF ACCELERATOR-DRIVEN
SYSTEMS
In a previous national review working party held by the Ministry
of Education, Culture, Sports, Science and Technology (MEXT) of Japan,
the party suggested to us the international cooperation with foreign
countries to support studies of accelerator-driven systems (ADS).
In this autumn, JAEA joined three international meetings for ADS
development in foreign countries.
One was held at the Belgium Nuclear Research Centre (SCK・CEN)
about the research and developments for the safety issues of a Multi-
purpose hybrid research reactor for high-tech applications (MYRRHA).
A variety of research activities on MYRRHA design and also the
application of lead-bismuth eutectic (LBE) alloy for spallation target
and coolant of a subcritical core are performed in Europe.
Participation in MYRRHA program is one of the important items to
accelerate the realization of long-lived nuclide transmutation by ADS.
After the meeting, items for cooperation were discussed at SCK・CEN.
Another meeting concerning spallation target material
technologies was also held in Europe. In addition, a specialist
meeting for post irradiation examinations (PIE) for the Megawatt Pilot
Experiment (MEGAPIE) project was held at the same place. The MEGAPIE
is an international 1MW LBE spallation target experiment conducted
using the Spallation Neutron Source (SINQ) facility in Paul Scherrer
Institute in 2006. Japan is one of the participants who received
irradiated test pieces of the MEGAPIE target and showed some PIE
results. These results will be summarized as a database for LBE
target, and will be useful information for design and lifetime
evaluation of the ADS Target Test Facility, TEF-T, in the J-PARC
project.
The third meeting, Asian network initiatives for ADS and Nuclear
Transmutation Technologies, was held in China. The main participants
are from Japan, Korea and China to share information for ADS design
such as accelerators, spallation target design, LBE handling
technologies and subcritical reactor properties.
Throughout these international meetings, there is a consensus that
international cooperative studies to solve common issues are expected
to realize the innovative nuclear systems.
---------------------------------------------------------------------
6. [Safety Division] by Tetsuro ISHII
---------------------------------------------------------------------
THE SAFETY AUDIT
A J-PARC safety audit was conducted by outside auditors (Prof.
Takano of Keio Univ. and Prof. Ishibashi of Kyushu Univ.) on Oct. 21.
They pointed out future issues in the management system, particularly
the importance of sustaining the current high safety awareness.
Improvement of the safety management system will be effected in
response to this result.
THE SAFETY INSPECTION IN THE 50-GEV MAIN RING (MR) AND HADRON
EXPERIMENTAL FACILITY (HD)
The safety inspection requested by the Nuclear Regulation
Authority (NRA) was successfully conducted on Dec. 3 by the Nuclear
Safety Technology Center (NUSTEC).
The inspection items are as follows:
1) Shutdown of the magnet power supply on abnormality detection of
the beam extraction system
2) The target container air-tight
3) Monitoring of the radioactive concentration in the gas at the
beam line tunnel
4) Improvement of visibility of radiation monitoring information
5) Setting the alarm for warning level
APPLICATION FOR LICENSES OF THE OPERATION WAS GRANTED
The application for licenses of the operation of the whole
facility was granted by NRA on Dec. 11. The main topic was the
enhancement of the beam intensity for the 1MW operation of MLF.
---------------------------------------------------------------------
7. [Editorial Note]
---------------------------------------------------------------------
In case you do not wish to receive this Newsletter in the future,
please send an email to news-l-ctl@ml.j-parc.jp and simply write one
sentence in the body of the message as unsubscribe.
If you wish to receive, write one sentence in the body of the
message as subscribe.
You can get a help with a sentence of "help" in the body.
Information on the project can be also obtained at the web site:
http://j-parc.jp/index-e.html
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Editorial Board:
Toshifumi TSUKAMOTO (Chair): toshifumi.tsukamoto@kek.jp
Kaoru SHIBATA: shibata.kaoru@ jaea.go.jp
Takashi ITO: itou.takashi@jaea.go.jp
Dick MISCHKE (English Editor): mischke@triumf.ca
Junko BEANBLOSSOM (Secretary): beanblossom.junko@jaea.go.jp
++++++++++++++++End of Letter++++++++++++++++++++++++++++++++++++++++