[Neutron] J-PARC Newsletter No.56

shibata.kaoru shibata.kaoru at jaea.go.jp
Wed Oct 29 02:29:08 CET 2014


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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 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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