[Neutron] J-PARC Newsletter No.54

Wed Apr 30 08:06:47 CEST 2014

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     J-PARC Project Newsletter
                                                 No.54, April 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]

400 MeV LINAC ENERGY UPGRADE WAS SUCCESSFULLY ACHIEVED.
USER OPERATION FOR MLF HAS STARTED.

2. [Accelerator Division]

THE DESIGNED 400 MEV BEAM WAS ACHIEVED IN THE LINAC ON JANUARY 17, 2014. 
THE BEAM DELIVERY FROM RCS IS STARTED FOR THE MLF USERS ON FEBRUARY 17,
2014. 
BEAM STUDY OF THE MAIN RING SYNCHROTRON (MR) WAS RESUMED AT THE END OF MARCH
2014.

3. [Particle and Nuclear Physics Division]

INTERNATIONAL REVIEWS FOR IMPROVEMENTS OF HADRON EXPERIMENTAL FACILITY. 
RECENT RESULTS OF SEARCHING FOR NEUTRON RICH HYPERNUCLEI.
T2K STATUS: RELEASE OF THE RESULT WITH ALL DATA ACCUMULATED SO FAR AND
MAINTENANCE WORK FOR NEUTRINO BEAM OPERATION FROM MAY.
CONSTRUCTION OF SUPER-CONDUCTING MAGNET SYSTEM FOR THE MU-E CONVERSION
SEARCH EXPERIMENT HAS STARTED. 
PREPARATION OF A PRECISE MEASUREMENT OF MUON MAGNETIC AND ELECTRIC DIPOLE
MOMENTS IS IN PROGRESS.
FIFC: FACILITIES IMPACT AND FUNDING COMMITTEE.

4. [Materials and Life Science Division]

STEADY NEUTRON PRODUCTION WITH 300 KW PROTON BEAM WAS RESUMED WITH IMPROVING
THE PRESSURE WAVE MITIGATION IN MERCURY TARGET SINCE FEBRUARY 2014.
CONSTRUCTION OF THREE NEW INSTRUMENTS WAS STARTED. 
GENERAL NEUTRON PROPOSALS FOR 17 INSTRUMENTS WERE SUBMITTED FOR 2014A
PERIOD.
A NEW MUSR SPECTROMETER WAS INSTALLED AT THE D1 AREA.

5. [Nuclear Transmutation Section]

PROMOTE TRANSMUTATION STUDY AS AN OPTION OF NUCLEAR WASTE MANAGEMENT.

6. [Safety Division]

THE 18TH RADIATION SAFETY COMMITTEE OF J-PARC MET IN JANUARY.
THE SAFETY INSPECTION OF NEW MUON BEAMLINE IN THE MATERIALS AND LIFE SCIENCE
EXPERIMENTAL FACILITY (MLF).

7. [Editorial Note]

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1. [Overview] by Yujiro IKEDA
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 400 MeV LINAC ENERGY UPGRADE WAS SUCCESSFULLY ACHIEVED
 USER OPERATION FOR MLF HAS STARTED

     1) The year of 2014 has started with an exciting achievement that the
LINAC energy upgrade to 400 MeV was successfully demonstrated by the
accelerator team on January 17. It should be an important step forward to
the 1MW power goal of J-PARC.

     2) Along a schedule for recovery of the Hadron Experimental Facility,
restructuring of the beam-line structure, shielding block realignment,
installation of a new air-conditioning system, extension of a building for
the radiation control, etc., have been conducted and there is steady
progress in all work in the experimental hall.

     3) Resuming the user beam operation to MLF with 300 kW power on
February 17 was encouraging news and after a 9-months long effort on
preventive measures to the Hadron accident last year. This accomplishment by
J-PARC team is also worthy of praise.

     4) International Advisory Committee (IAC) meeting was held on 10th and
11th March, 2014. Most importantly, facility safety aspect was highlighted
along with J-PARC progress in the restart of user operation. Accelerator
Technical Advisory Committee (ATAC), Neutron Advisory Committee (NAC) and
Muon Advisory Committee (MAC) meetings were also held independently, but
associated with IAC. Committees gave us invaluable and critical comments in
terms of being a real user facility.

     5) 2014 Budget scheme was announced that operation of 8 cycles for RCS
is to be assured, but it revealed severe cut for MR operation. All efforts
are to be put on a possible recovery of operation cycle of MR.

     6) Two proposals of large scale facility associated with J-PARC were
selected in review of the Japanese Science Council as top 27 important
project to be pursued.

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2. [Accelerator Division] by Tadashi KOSEKI
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 THE DESIGNED 400 MEV BEAM WAS ACHIEVED IN THE LINAC ON JANUARY 17, 2014 
 THE BEAM DELIVERY FROM RCS IS STARTED FOR THE MLF USERS ON FEBRUARY 17,
2014 

     The beam commissioning of the linac with a newly installed accelerating
structure system, Annular-ring Coupled Structure linac (ACS), was started on
December 16, 2013. The designed beam energy of 400 MeV was achieved on
January 17, 2014. The beam commissioning of the Rapid Cycling Synchrotron
(RCS) was started on January 30, 2014 and the 400 MeV injection beam was
accelerated to 3 GeV on February 5, 2014. For the beam injection at 400 MeV,
power supplies of horizontal shift-bump magnets were replaced with new ones
in the 2013 shutdown period. The new power supply has 16 power supplies in
parallel and is designed to reduce the current ripple, which induced dipole
oscillation of the circulating beam and caused beam losses. At the present
time, the new power supplies have a problem of current droop on the flat
top. This effect is temporarily compensated by the other injection magnets,
two pulse steering magnets in the beam transport line just upstream of the
injection straight section, and four paint bump magnets in the injection
straight section of the RCS. In the accelerator study, the RCS has
demonstrated the high beam intensity of 560 kW, the same level of the
maximum intensity before the energy upgrade of the linac. The beam losses
are drastically improved by the reduced current ripple in the new shift bump
magnet power supplies. The remaining beam losses are only due to the foil
scattering in the charge exchange beam injection. This high power
demonstration with low beam losses is an important milestone for 1 MW beam
operation in the near future. The user operation of the Materials and Life
Science Experimental Facility (MLF) was resumed on February 17, 2014 with
the beam intensity of 300 kW after the nine months beam shutdown since May
24, 2013. The user operation will be continued till the end of June 2014
before the summer shutdown.

     For the upgrade of the linac peak current, a new front-end system,
which is composed of a cesium-seeded rf-driven negative-hydrogen ion source
and a new Radio Frequency Quadrupole linac (RFQ) for the peak current of 50
mA, is now being tested in an RFQ test stand. On February 6, 2014, the first
50-mA H- beam was successfully accelerated by the RFQ. After a test of
long-term stability through continuous beam operation, the new front-end
system will be installed in the linac tunnel in the 2014 summer shutdown
period.

 BEAM STUDY OF THE MAIN RING SYNCHROTRON (MR) WAS RESUMED AT THE END OF
MARCH 2014   

     Beam study of the MR was restarted on March 24, 2014. The injection
beam from the RCS was accelerated to 30 GeV and extracted by the fast
extraction system to the abort beam dump on March 30 for the first time
after the accident in the hadron hall. To improve the optics correction in
the beam transport line between the RCS and the MR (3-50 BT), one
multi-ribbon profile monitor (MRPM), three beam position monitors (BPMs) and
three steering magnets have been additionally installed in the collimator
section of the 3-50BT in the 2013 shutdown. The dispersion free optics in
the collimator section of the 3-50BT has been successfully obtained. This
optics correction is necessary to control the balance of the beam losses in
the two collimator systems, the 3-50 BT collimators and the MR collimators,
for the high power operation in the near future.  

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3. [Particle and Nuclear Physics Division] by K. OZAWA, T. TSUKAMOTO, S.
MIHARA, T. KOMATSUBARA
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 INTERNATIONAL REVIEWS FOR IMPROVEMENTS OF HADRON EXPERIMENTAL FACILITY 
 RECENT RESULTS OF SEARCHING FOR NEUTRON RICH HYPERNUCLEI (by K. OZAWA)

     Review committees for the J-PARC Hadron Facility were convened to
evaluate renovation and upgrade plans of the facility.
    The first one was held on October 8 and 9 to review our renovation plan
of the target and related matters. The plan was intensively discussed mainly
from several viewpoints including the safety. The committee agreed the plan
is suitable for the renovation, and they also provided a great deal of
advice. More details of the meeting are shown on the web page:
http://j-parc.jp/en/news/2013/J-PARC_News-e1310.html
     A follow-up meeting was held on January 29 to report advances to the
committee.
     On January 30, another review committee was held for the primary beam
line to be constructed at the Hadron facility. The design and safety issues
were discussed at the meeting. The committee approved the design basically
filled the requirements for considerations on the safety.

     Results of the J-PARC E10 experiment were published, entitled "Search
for 6(Lamda)H hypernucleus by the 6Li(pi-,K+) reactions at p_pi = 1.2 GeV/c"
(Phys. Lett. B729 (2014) 39). The experiment aimed to search for
neutron-rich Hyper6(Lambda)H hypernucleus; the results set an upper limit of
the production cross section.

 T2K STATUS: RELEASE OF THE RESULT WITH ALL DATA ACCUMULATED SO FAR AND
MAINTENANCE WORK FOR NEUTRINO BEAM OPERATION FROM MAY (by T.TSUKAMOTO)

     T2K released the results on muon-neutrino disappearance using all data
accumulated so far (until May 2013) corresponding to 6.57 x 10^20 POT and on
combined analysis with muon-neutrino disappearance and electron-neutrino
appearance. The results were presented at Rencontres de Moriond, 2014. 
http://moriond.in2p3.fr/
https://indico.in2p3.fr/materialDisplay.py?contribId=176&sessionId=4&materia
lId=slides&confId=9116.  
     Maintenance work for the neutrino beam facility is being carried out.
There are many items as reported in the previous newsletter (#53). We would
like to report as one of results of maintenance that replacement of all
three magnetic horns was carried out successfully by the end of Mar. The
neutrino beam facility and the near detector ND280 will be prepared for
neutrino beam operation which is planned from May.

 CONSTRUCTION OF SUPER-CONDUCTING MAGNET SYSTEM FOR THE MU-E CONVERSION
SEARCH EXPERIMENT HAS STARTED 
 PREPARATION OF A PRECISE MEASUREMENT OF MUON MAGNETIC AND ELECTRIC DIPOLE
MOMENTS IS IN PROGRESS (by S. MIHARA)

     The COMET experiment aims at searching for the mu-e conversion, which
is strictly forbidden in the standard model (SM), with a target sensitivity
of 10^{-14} in Phase I and 10^{-16} in Phase II by using the J-PARC
high-power proton beam. In this experiment, a long chain of super-conducting
solenoid magnets will be used to collect pions/muons and transport muons to
the experiment area. In early 2014, production of solenoid magnet coils has
been successfully started. Coil winding will be continued until 2015 to
produce in total 10 coils. They will be assembled in a cryostat to form a
large collection magnet to produce a strong magnetic field surrounding the
pion production target. R&D of detectors to identify the signal electrons is
also in progress; detector prototypes were tested using an electron beam in
March 2014. Preparation of the muon magnetic and electric dipole moment
measurement is also in progress. Precise measurement of these properties of
muons is considered to be an important clue to investigate the physics
beyond the SM. At the beginning of 2014, a series of test experiments
verifying efficient production of muonium, used as a muon source in this
g-2/EDM measurement, have been conducted both at TRIUMF and J-PARC MLF.
Detector R&D is being intensively performed in the framework of the
international collaboration.

     Related Meetings:
     COMET and Muon g-2/EDM collaborations had a joint workshop on the
silicon detector at LPNHE in Paris in February 2014. A mini-collaboration
meeting of the g-2/EDM experiment was held at J-PARC in March 2013.

 FIFC: FACILITIES IMPACT AND FUNDING COMMITTEE (by T. KOMATSUBARA)

     This committee evaluates the feasibility of the various aspects
including the safety-related issues of the experiments in the Hadron
Experimental Facility and in other facilities of J-PARC. It was held on
March 24 and the evaluation will be reported in the next PAC meeting in May.

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4. [Materials and Life Science Division] by Masatoshi ARAI
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 STEADY NEUTRON PRODUCTION WITH 300 KW PROTON BEAM WAS RESUMED WITH
IMPROVING THE PRESSURE WAVE MITIGATION IN MERCURY TARGET SINCE FEBRUARY 2014

     1) Neutron Source
     Operating the pulsed spallation neutron source was resumed on the 11th
of February, 2014. The flow rate of helium gas micro-bubbles into the
mercury target vessel was increased up to 7.2 l/m, which was much higher by
a factor of six than the previous rate. This increase of the flow rate was
achieved after a maintenance of the mercury circulation loop. It enhanced
mitigation for the effect caused by the pressure wave induced in mercury by
a factor of three to four. The user program for the 2013B period was started
on the 17th of February, 2014 with the 120 kW beam. The beam power was
increased up to 220 kW on the 19th of February and then finally recovered to
300 kW on the 26th of February.
     At the 3-GeV proton beam transport facility, the proton beam profile
that was a Gaussian shape was successfully flattened with two octupole
magnets which were installed in the last summer, so that the peak height was
reduced by 30 to 40%. 

 CONSTRUCTION OF THREE NEW INSTRUMENTS WAS STARTED
 GENERAL NEUTRON PROPOSALS FOR 17 INSTRUMENTS WERE SUBMITTED FOR 2014A
PERIOD

     2) Neutron Instruments and Science
     During the period of shutdown after the accident in the Hadron
Experimental Facility, construction of three new instruments was started:
BL06 (Vin Rose, Spin Echo Spectrometers), BL22 (RADEN, Pulsed Neutron
Imaging Instrument) and BL23 (POLANO, Polarized Neutron Spectrometer). The
user operation for 2013B (the second half of FY2013) was started on the 17th
of February, and it was ended on the 7th of April.
     The general proposals for 2014A (from the 14th of April to the 3rd of
December) was called for 17 instruments, and 283 neutron proposals were
submitted. Those proposals were reviewed by the Neutron Science Proposal
Review Committee, and finally 155 proposals were approved by the MLF
advisory board; in addition, 43 proposals were reserved. The total
competition rate (requested/ available beam time) is as high as 2.1 times. 

 A NEW MUSR SPECTROMETER WAS INSTALLED AT THE D1 AREA

     3) Muon Science Facility (MUSE)
     A new muSR spectrometer was installed at the D1 area. It consists of
1280 scintillators (640 telescopes) with their scintillation light detected
by multi-pixel avalanche photo diodes (MPPCs) covering a total solid angle
of 23.4%, which is 3.3 times larger than the conventional D1 spectrometer,
D-OMEGA1. The spectrometer is equipped with a Helmholtz coil up to 4 kG,
separated by a gap of 135 mm, which can be rotated by 90 degree, and allows
us to apply either transverse or longitudinal magnetic field. It is also
designed to be connected to a fly path chamber with a diameter of 410 mm.
During the commissioning, it was demonstrated that 200 million of coincident
positron events per hour were collected for a sample of 15 x 15 mm2 with a
20 mm collimator. The event rate is 2-3 times higher than that in ISIS-RAL,
thanks to the stronger muon beam intensity of J-PARC.

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5. [Nuclear Transmutation Section] by Toshinobu SASA
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 PROMOTE TRANSMUTATION STUDY AS AN OPTION OF NUCLEAR WASTE MANAGEMENT

     Last autumn, a national review committee, which is hosted by Ministry
of Education, Culture, Sports, Science and Technology in Japan, recommended
to promote partitioning and transmutation (P-T) technology as an important
alternative option of future nuclear waste management. Even though the
construction of J-PARC Transmutation Experimental Facility(TEF) is not
approved yet, the supplemental budget was allocated to enhance research and
development activities not only for the design of TEF but also for P-T fuel
cycle studies.
     For the design study of TEF, the supplemental budget was allocated to
the experimental studies of lead-bismuth eutectic (LBE) handling for the ADS
Target Test Facility (TEF-T) and remote operation of Minor Actinide (MA)
bearing fuel to be used in Transmutation Physics Experimental Facility
(TEF-P). For the study of LBE handling, engineering studies for loop
equipment including an electromagnetic pump will be performed with newly
prepared target mockup loop. Mockup of spallation target for material
irradiation will be also prepared for cold loop tests. As for the remote
operation tests for MA-bearing fuel, confirmation of remote operation, which
is designed to minimize the effect of experimental accuracy and to maximize
the reproducibility of experiments simultaneously, will be performed. The
experimental equipment will be completed within fiscal year 2014.

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6. [Safety Division] by Tetsuro ISHII
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 THE 18TH RADIATION SAFETY COMMITTEE OF J-PARC MET IN JANUARY

     The 18th Radiation Safety Committee of J-PARC met on Jan. 22 and
discussed the alternative application of J-PARC facilities and the revised
regulations on prevention from radiation hazards of J-PARC. The main topic
of the application was about the renovation of the Hadron Experimental
Facility.
    The application for a license of the renovation of the Hadron
Experimental Facility was approved by the Nuclear Regulation Authority (NRA)
on Mar. 19.

 THE SAFETY INSPECTION OF NEW MUON BEAMLINE IN THE MATERIALS AND LIFE
SCIENCE EXPERIMENTAL FACILITY (MLF) 

     The safety inspection of the new muon beamline (U-line) in the MLF was
successfully conducted on Mar. 3 by the Nuclear Safety Technology Center
(NUSTEC).

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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++++++++++++++++++++++++++++++++++++++++