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J-PARC Project Newsletter
No.56, October 2014
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]
FY2015 BUDGET.
J-PARC SYMPOSIUM.
TEF-TAC (TRANSMUTATION EXPERIMENTAL FACILITY TECHNICAL ADVISORY
COMMITTEE).
2. [Accelerator Division]
FRONT END SYSTEM OF THE LINAC HAS BEEN REPLACED.
3. [Particle and Nuclear Physics Division]
SEARCH FOR A PENTAQUARK STATE USING A DIFFERENT BEAM ENERGY.
MAINTENANCE OF NEUTRINO BEAM LINE FOR COMING OPERATION.
PROGRESS IN MUON PARTICLE PHYSICS PROGRAMS.
4. [Materials and Life Science Division]
MAINTENANCE WORK OF NEUTRON SOURCE COMPONENTS.
ONE HUNDRED SIXTY ONE GENERAL NEUTRON PROPOSALS WERE APPROVED FOR
2014B PERIOD.
CONSTRUCTION OF THREE NEW INSTRUMENTS AND MAINTENANCE FOR EXISTING
INSTRUMENTS.
AT THE U-LINE, THERMAL INSULATION WINDOW WAS FIXED.
5. [Nuclear Transmutation Section]
STEADY PROGRESS OF R&Ds FOR TRANSMUTATION EXPERIMENTAL FACILITY (TEF)
CONSTRUCTION.
6. [Safety Division]
THE 19TH & 20TH RADIATION SAFETY COMMITTEES OF J-PARC.
APPLICATION FOR LICENSES OF THE OPERATION WAS GRANTED.
7. [Editorial Note]
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1. [Overview] by Yujiro IKEDA
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FY2015 BUDGET
J-PARC SYMPOSIUM
TEF-TAC (TRANSMUTATION EXPERIMENTAL FACILITY TECHNICAL ADVISORY
COMMITTEE)
1) The FY2015 budget proposal of J-PARC has been recently
submitted from MEXT (Ministry of Education, Culture, Sports and
Technology) to MOF (Ministry of Finance). Although it has not yet
been finalized, the budget situation of KEK seems very severe for
keeping the requested amount of beam time.
2) Following the public lecture on July 12, the second J-PARC
symposium was held at the Tsukuba International Conference Center
from July 13 to July 15. A workshop on nuclear physics was also held
on July 16 to commemorate outstanding achievements by Prof. Shoji
Nagamiya, the former Director of the J-PARC Center.
3) During the summer shutdown time from July 1, 2014, a
tremendous effort has been invested on maintenance and upgrade work
of all facilities. Concurrently recovery work of the Hadron
Experimental Facility has been continued and has reached the important
stage of the target replacement.
4) The first meeting of the Technical Advisory Committee on the
accelerator driven nuclear transmutation experimental facility (TEF)
was held on July 10 and 11 to promote the facility construction
project at an early time. (See the report from the Nuclear
Transmutation Group)
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2. [Accelerator Division] by Tadashi KOSEKI
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FRONT END SYSTEM OF THE LINAC HAS BEEN REPLACED
During the summer shutdown period from July to September,
maintenance of the accelerator components and various improvements
for the operation with higher beam intensity were made in the
accelerators.
For the linac, replacement of the front-end part to increase the
peak current from 30 mA to 50 mA was one of the most important
improvements in this shutdown period. The peak current of 50 mA is
necessary to achieve the design beam intensities, 1 MW for the RCS
and 750 kW for the MR. The new front-end system consists of an rf
(radio-frequency)-driven ion source and RFQ for 50 mA operation. The
ion source, which is based on a design of the ion source of Spallation
Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL), was
developed. It achieved the maximum peak current of 70 mA by seeding
cesium in a test bench. After a demonstration of one-month continuous
operation with 50 mA at the output of the RFQ, the new front-end
system was installed in the linac tunnel in August 2014.
In order to chop the 50 mA beam for making the intermediate time
structure of the linac beam pulse, the rf chopper cavity was also
replaced with a newly fabricated one, which has a larger aperture and
longer gap length between electrodes to decrease unexpected beam loss
in the chopper. Two new scrapers were also installed to absorb the
higher power of the deflected beam by the chopper cavity.
A beam dump called "100 degree dump" is used to dump the proton
beam, which is generated at a beam collimator section in the beam
transport line between linac and the RCS. High residual radioactivity
on the accelerator components near the beam dump is one of the
concerns for high power beam operation. To decrease the residual
activity, the 10 mm thick Ni (Nickel) vacuum window of the beam dump
has been replaced with a 2 mm thick Ti (Titanium) window with
radiation shields. Additionally, a wire scanner and a current
transformer are installed just upstream of the beam dump to monitor
the dumped beam.
In the MR, a new rf cavity was installed in the ring tunnel in
this September. The cavity has been developed for near future high
repetition rate operation of 1 Hz. It has a new type of magnetic
alloy core, named FT3L (Hitachi Metals), which is processed by
annealing in a magnetic field. The core shows two times higher
impedance than present cores, which are used in the MR and RCS. The
newly installed FT3L loaded rf cavity has five gaps and produces 75
kV/ cavity while the other present cavities in the MR produce 30 kV/
cavity in routine operation.
The J-PARC accelerator resumed beam operation on September 29.
After beam study of the linac with the new front-end system, the first
trial of 1-MW beam demonstration of the RCS will be started in the
middle of October 2014.
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3. [Particle and Nuclear Physics Division] by M. MORITSU, K. OZAWA,
T. TSUKAMOTO and S. MIHARA
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SEARCH FOR A PENTAQUARK STATE USING A DIFFERENT BEAM ENERGY
(by M. MORITSU and K. OZAWA)
The study of exotic hadrons, which cannot be interpreted as
ordinary three-quark baryons or quark-antiquark mesons, would offer a
good opportunity for us to investigate low-energy quark dynamics. The
first observation of pentaquark called Theta+, which has a strangeness
quantum number +1 with its minimal quark configuration of uudds-bar,
was reported at the Laser Electron Photon beamline (LEPS) of Spring-8.
Pentaquarks were intensively searched at many experimental facilities,
and both positive and negative results have been reported including
the one from the J-PARC E19 experiment.
Updates from the J-PARC E19 collaboration, using a different beam
energy, will be published soon in Phys. Rev. C. (http://arxiv.org/abs/1407.0669
). The Theta+ has been searched for via the pi- + p -> K- + X
reaction with beam momenta of 1.92 and 2.01 GeV/c at the K1.8 beam
line of the J-PARC Hadron Experimental Facility. A missing mass
resolution of 2 MeV (FWHM) was achieved, but a sharp peak structure
expected for Theta+ was not observed with both energies. The upper
limit on the forward production cross section was found to be 0.28 ub/
sr at the 90% C.L. Constraints on the Theta+ decay width were also
evaluated with theoretical calculations using an effective Lagrangian
model. The present result implies that the width should be less than
0.36 and 1.9 MeV for the spin-parity of 1/2^+ and 1/2^- respectively.
The result will be published in Physical Review (Phys. Rev. C70,
035205 (2014)).
MAINTENANCE OF NEUTRINO BEAM LINE FOR COMING OPERATION
(by T. TSUKAMOTO)
Neutrino beam line maintenance is being carried out for upcoming
operation from the end of October.
One major maintenance work is replacement of power supplies
for normal-conducting magnets of the proton beam-line. The old power
supplies were brought from KEK-PS beam lines and had been used for
more than 30 years. New power supplies were delivered in August and
installed in September. Tests with magnets are being carried out and
all will be ready for upcoming beam operation.
Other important items are installation of new power supply for
horns and maintenance of beam monitor CTs (current transformer) and
SSEM (Segmented Secondary Emission profile Monitor), which is also
being carried out successfully.
T2K near detector magnet was opened in July for maintenance of
P0D (pi-zero detector) and will be closed in the beginning of October
to start operation from the middle of October.
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. Recently the prototype of the trigger counter was
tested with an electron beam around 105 MeV. A series of aging tests
of the CDC wire has been performed to understand the detector behavior
in the high radiation environment. Production of superconducting
magnet coils is also ongoing along with detailed design work of the
magnet cryostat and radiation shield surrounding the target used for
protecting coils from heavy radiation. Preparation for a precision
determination of the muon magnetic and electric dipole moments is also
in progress. A new method of efficiently producing muonium from
laser-ablated silica aerogel in vacuum was published in the PTEP
journal and also released to press (*). Preparation for further
optimization is in progress. A test experiment to develop a source of
negatively charged muonium was started to test the muon acceleration
technique. Evaluation of prototype silicon-strip sensor and frontend
electronics for decay positron detection were completed. They will be
tested with a positron beam at the end of September.
(*) http://j-parc.jp/ja/topics/2014/Pulse140918.html (in Japanese)
Related meeting
The COMET group had a collaboration meeting at Tbilisi State
University in Georgia in September.
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4. [Materials and Life Science Division] by Masatoshi ARAI
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MAINTENANCE WORK OF NEUTRON SOURCE COMPONENTS
1) Neutron Source
Various maintenances have been carried out during the summer
shutdown period. In the level survey carried out in last and this
summer, 0.6 mm deviation of the floor levels in the 3-GeV proton beam
transport (3NBT) tunnel between the MLF building and the upstream
section was observed. Therefore, magnets and beam monitors of 3NBT
were realigned to compensate for the deviation.
The proton beam window made from aluminum alloy was inspected by
a camera from downstream. It was confirmed that the window surface of
the atmospheric pressure side was sound after irradiation of 300-kW
beam for 585 MWh. Periodical inspection of the cryogenic hydrogen loop
was conducted and an electric motor for a helium compressor was
overhauled for the first time.
ONE HUNDRED SIXTY ONE GENERAL NEUTRON PROPOSALS WERE APPROVED FOR
2014B PERIOD
CONSTRUCTION OF THREE NEW INSTRUMENTS AND MAINTENANCE FOR EXISTING
INSTRUMENTS
2) Neutron Instruments and Science
The general proposals for 2014B (289 neutron proposals) were
reviewed by the Neutron Science Proposal Review Committee. Finally
161 proposals were approved by the MLF advisory board, in addition 37
proposals were reserved. The board accepted the beam schedule for
2014B extended till April, 2015. As a result, the total competition
rate (requested/ available beam time) is moderated to be 1.87 times.
In this summer shutdown period, construction of three new
instruments is being carried out: BL06 (Vin Rose, Spin Echo
Spectrometers), BL22 (Pulsed Neutron Imaging Instrument) and BL23
(POLANO, Polarized Neutron Spectrometer). Also maintenance and upgrade
works for existing instruments are conducted. Maintenance for
choppers, re-alignment of beam-transports, installation of detectors,
upgrading of shielding are continued till the end of October.
AT THE U-LINE, THERMAL INSULATION WINDOW WAS FIXED
3) Muon Science Facility (MUSE)
In the category of the muon user's program 2014B, 46 proposals
(Q1:18, Q2:28, S1:1, S2:1) were submitted.
Since it is found that the thermal insulation window of the
front-end superconducting magnet in the superconducting curved
solenoid was broken at the U-Line, we removed shields in the vicinity
of the superconducting curved solenoid. First we prepared a temporal
radiation control area to prevent radioactive materials from spilling
out and then moved the curved solenoid from the primary tunnel to the
experimental area in order to fix it. All the fixing works were
completed and it was verified that it was cooled down below the
superconducting temperature in August.
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5. [Nuclear Transmutation Section] by Toshinobu SASA
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STEADY PROGRESS OF R&Ds FOR TRANSMUTATION EXPERIMENTAL FACILITY (TEF)
CONSTRUCTION
The first TEF Technical Advisory Committee (T-TAC) met on July
10th and 11th at Tokai, and toured the J-PARC facilities including the
planned TEF construction site. The T-TAC reviewed design for TEF-T and
TEF-P based on technical information given by J-PARC staff, and
submitted a report of recommendation on July 31th. The report
concludes that the future scientific opportunities offered by TEF are
world-class and the appropriate resources can contribute in a
meaningful way to Japan's new strategic energy plan. In addition,
various essential comments were provided such as clarification of
design parameters, delivering of integrated safety analysis,
intensifying R&D on oxygen sensors and verification of the
availability of minor actinide fuel.
Last year, the Ministry of Education, Culture, Sports, Science
and Technology (MEXT) launched a working party (WP) to discuss the way
forward to facilitating the R&D on Partitioning-Transmutation (P-T)
technology using accelerator-driven system (ADS). Issues to be
reviewed in the WP include the current P-T research activities, TEF
construction in J-PARC, and international collaboration to accelerate
ADS R&Ds. In November 2013, the WP issued an interim report and it
mentioned that it should step up to the next stage to encourage the
research and development activities for ADS based P-T technology.
In this summer, WP held two meetings to review the progress of
R&Ds especially for the activities related to TEF construction.
Discussed are various activities to realize lead-bismuth eutectic
alloy spallation target for ADS Target Test Facility, TEF-T, minor-
actinide loaded core for Transmutation Physics Experimental Facility,
TEF-P, and efforts to enhance R&D activities such as international
collaboration and human resource development. In the beginning of
September, the WP summarized their opinion to the public. In the
report, WP approved the R&D for TEF construction was appropriate and
progressed steadily. Additionally, the knowledge from Russian lead-
bismuth application and academic review for TEF-P licensing were
recommended. The WP also approved enhancing activities related to the
TEF construction such as ground survey for candidate area of TEF
building.
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6. [Safety Division] by Tetsuro ISHII
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THE 19TH & 20TH RADIATION SAFETY COMMITTEES OF J-PARC
The 19th Radiation Safety Committee of J-PARC met on Apr. 9 and
discussed the alterative application of J-PARC facilities. The main
topics were safety measures for the operation of the Hadron
Experimental Facility, and a new secondary beam line BL22 in the
Materials and Life Science Experimental Facility (MLF).
The 20th Radiation Safety Committee of J-PARC met on Jul. 31 and
discussed the alterative application of J-PARC facilities. The main
topic was the enhancement of the beam intensity for the 1MW operation
of MLF.
APPLICATION FOR LICENSES OF THE OPERATION WAS GRANTED
The application for licenses of the operation of the whole
facility was granted by the Nuclear Regulation Authority (NRA) on Sep.
9. The main topics were the safety measures for the operation of the
Hadron Experimental Facility, and the new secondary beam line BL22 in
MLF.
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7. [Editorial Note]
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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
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