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J-PARC Project Newsletter
No. 39, March 2010
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]
3 GeV RING MARKED 300 kW.
BUDGET DECIDED AT THE GOVERNMENT.
NEW IAC MEMBERS WERE APPOINTED.
THE NUMBER OF USERS INCREASES STEADILY.
J-PARC APPEARS ON SAZAE-SAN COMIC MOVIE ON TV.
2. [Accelerator Division]
SUCCESS IN 300 kW TEST OPERATION OF RCS.
120 kW OPERATION FOR MLF USER PROGRAM.
HIGH POWER TEST OF MR.
3. [Nuclear and Particle Physics Division]
SECONDARY BEAM COMMISSIONING STARTED.
9TH PAC MEETING HELD ON JANUARY 15-17.
STATUS OF THE NEUTRINO FACILITY.
4. [Materials and Life Science Division]
THE WORLD STRONGEST NEUTRON PULSE WAS PRODUCED.
THE USER OPERATION FOR 2008B PERIOD HAS BEEN STARTED.
THE WORLD STRONGEST PULSED MUON BEAM WAS ACHIEVED AT
J-PARC MUSE ON THE NOVEMBER, 2009 BEAM CYCLE.
5. [Exotic Nuclear Science Group]
A COMPACT TWO-GAP PRE-BUNCHER WAS NEWLY INSTALLED
UPSTREAM OF THE LINAC OF THE TOKAI RADIOACTIVE ION
ACCELERATOR COMPLEX (TRIAC) FOR NUCLEAR ASTROPHYSICS
EXPERIMENTS.
6. [Nuclear Transmutation Section]
INTERNATIONAL ADS WORKSHOP WAS ORGANIZED
7. [Safety Division]
THE SAFETY INSPECTION OF THE HADRON EXPERIMENTAL FACILITY
SUCCESSFULLY CONDUCTED BY NUSTEC.
8. [Information System Division]
HIGH SPEED NETWORK SINET SUPPORTS J-PARC EXPERIMENTS
9. [Announcement of Symposia and Meetings]
10. [Editorial Note]
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1. [Overview] by Shoji NAGAMIYA
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3 GeV RING MARKED 300 kW
In November we reached 120 kW, as announced in the
previous Newsletter. Subsequently in December of 2009 the
acceleration of 300 kW was successfully achieved for one
hour. This implies that beam intensity per pulse reached
for a short time the highest in the world, since pulse
interval is longer at J-PARC than at SNS. Currently, we
returned back to a standard 120 kW operation and it
has been very stable. The run is very smooth during the
past three months. Please note that the power at KEK-Booster
ring was 3 kW. We thus obtained 40 times the intensity as
compared to the KEK-Booster ring, though we are still
very far from the goal of 1 MW power.
BUDGET DECIDED AT THE GOVERNMENT
At the end of December and at the beginning of January
a new budget for JFY2010 was announced. We were allowed to
run 6 Cycles (10 Cycles is the maximum). As compared with
the goal for a budget at full intensity and full beam time,
the allocation of the operation budget in JFY2010 is 71 %
of this full amount. Namely, the total operation budget
that will be granted is 67.7 Oku Yen for KEK and 65.3 Oku
Yen for JAEA. In addition, the Linac Upgrade and neutron
beamlines were approved at JAEA (total of 25.0 Oku Yen for
JFY2010 plus JFY2009 Supplemental). You may know that the
government revitalization unit in the new cabinet tried to
make a large cut in the science budget for JFY2010. However,
the actual cut was not very dramatic. Our J-PARC received
even an increased operational budget as compared to the
corresponding one in the previous year.
NEW IAC MEMBERS WERE APPOINTED
From the spring of 2010 members of IAC, A-TAC, etc,
were renewed. New International Advisory Committee (IAC)
members are as follows: J. White (Australian U., Chair for
2010), J.-M.Poutissou (TRIUMF, Chair after 2011),
A. Taylor (RAL), B. Frois (CEA), S. Henderson (ORNL),
S. Tanaka (U. Tokyo), H. Fukuyama (Tokyo U. of Science),
I. Anderson (ORNL)*, S. Bertolucci (CERN)*, Y.-K. Kim (FNAL)*,
H. Montgomery(JLab)*, T. Roser (BNL)*, H. Stoecker (GSI)*,
E. Torikai (U. Yamanashi)*, T. Shintake (SPring-8)*,
with an asterisk are new members.
THE NUMBER OF USERS INCREASES STEADILY
The number of users is steadily increasing. Last November
the number exceeded 3000 persons*day in a month, which is
about 100 persons/day. Fifty percent are non Japanese (this
is a registered number at the Users Office so that the number
of visitors could be much more). The lack of lodging space is
now a big issue. As announced before, KEK is constructing about
50 lodgings (to start its operation from December of 2010).
Other efforts to increase lodging capability are also in
progress. The Tokai Village is cooperating to construct a
hotel. This village is also cooperating with us to construct
an access road which is directly connected to J-PARC from a
public main road, Rt. 245.
J-PARC APPEARS ON SAZAE-SAN COMIC MOVIE ON TV
Sazae-san is a very popular TV comic. It is broadcast
at 6:30 pm on every Sunday. In the opening screen of this
comic, a scene of J-PARC appears (though, only for a very
short time alone) from January to the end of March.
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2. [Accelerator Division] by Ainosuke ANDO
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SUCCESS IN 300 kW TEST OPERATION OF RCS (3-GeV Rapid
Cycling Synchrotron)
On December 10th, the 300-kW proton beam was guided to
the Hg-target of MLF (Material and Life science Facility) to
produce neutron beams for almost one hour. This high power
test was started at 10:45 because the official permission of
the maximum intensity is 250 kW*hour in every hour. The peak
power is considered as the highest in the world.
120 kW OPERATION FOR MLF USER PROGRAM
Since November 10th, the operation at 120 kW has been
started for the MLF user program. This is the expected
achievement after the drastic improvement and careful
conditioning of the RFQ linac. Since there are still some
issues to be solved for the power higher than 120 kW, for
example, beam loss due to multi-passage of the charge
exchange foil at injection to RCS and the huge energy
deposit on the Hg-target, the user program of MLF has been
carried out with the 120 kW operation. For the future an
operation around 200 kW is now under discussion for the MLF
user programs.
HIGH POWER TEST OF MR (50-GeV Synchrotron)
The MR is now operated with the cycle period of 3.52
sec and with six bunches (three batches) for the fast
extraction mode to produce a neutrino beam. In the one-shot
operation mode, 3.1E13 protons per pulse were successfully
extracted to an abort dump. This is equivalent of 42 kW
beam power if it is operated continuously, and also
corresponds to 60 kW for the design level of eight bunches
with a period of 3.3 sec. The dominant beam loss is ~2 %
occurring at collimators during about 20 ms just after each
batch injection. A simple estimation leads to a 200 W loss
for a 100 kW operation, which is well acceptable for the
present limit of 400 W. The high power operation has
revealed many issues. For example, non-negligible beam losses
at regions with a large momentum dispersion and at components
for injection and extraction and a large out-gas in the kicker
magnets. The latter one is sensitive to the peak beam current
and occurs often during acceleration, when the bunch length
becomes shorter. We admit afresh that observations and controls
of bunch shapes in both longitudinal and transverse directions
are extremely essential to realize stable high intensity beams.
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3. [Nuclear and Particle Physics Division]
by T.TAKAHASHI and J.IMAZATO
by Y.FUJII, Y.YAMADA and T.TSUKAMOTO
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SECONDARY BEAM COMMISSIONING STARTED
(by T.TAKAHASHI and J.IMAZATO)
Following the first delivery of a secondary beam in
K1.8BR in the fall of last year, the K1.8 beamline has been
commissioned during December. This beamline, taken off the
T1 production target and equipped with two stages of
electro-static separators (ESS), should deliver separated
K and pi beams up to 2.0 GeV/c. After confirming good
performance of the beam instruments such as MWPCs and
hodoscopes, all the beam line elements were started to be
tuned. By switching on the two ESS high voltages, the
enrichment of K+ to more than 80% content could be
successfully observed. This was, however, only the first
step toward full commissioning in the upcoming beam period
this year. During the beam tuning, the SKS spectrometer,
which had gone through cooling and an excitation test earlier,
was set in operation, and the basic performance of tracking
and particle identification was confirmed. Unfortunately,
the beam intensity of the slow extraction beam was still
weak and the beam spill structure has not yet been optimized
for carrying out high rate experiments. The E19 experiment
(pentaquark search) is now being prepared as the first SKS
experiment. At the same time, the neutral kaon KL beamline,
which is the K1.8 counterpart of T1, was commissioned and
made progress. For the beam tuning, efforts have been made
to survey KL and measure its beam profile using fiber
hodoscopes etc.
KL could be confirmed successfully by the three-pion decays,
with a yield consistent with expectations from simulation.
The collimator system, one of the key elements of this
beamline, was found to function satisfactorily and was
optimized for its position. These studies were also an
opening act for the following full beam survey planned this
year, in which neutron backgrounds should be investigated
in detail towards the E14 KOTO experiment (KL -> p0 nu nu-bar
rare decay). The K1.8BR beamline, which had been commissioned
and reported before, turned out to show a sufficiently high
K/pi ratio also in the subsequent beam study in December,
enough to start the E17 (He-3 kaonic X-ray) experiment
this year.
9TH PAC MEETING HELD ON JANUARY 15-17
(by J.IMAZATO)
The 9th PAC meeting was held on January 15-17 at the
KEK Tsukuba campus. Since half of the committee members come
to the end of their terms now, new appointed members joined
the meeting this time. Also, at the occasion of the first
beam delivery to T2K and the Hadron Hall, the status of
the J-PARC and the accelerator was reviewed. In addition
to four new experimental proposals, the currently running
experiments and preparing experiments were reported and
discussed for evaluation. The results will be published
soon as the meeting minutes.
STATUS OF THE NEUTRINO FACILITY
(by Y.FUJII, Y.YAMADA and T.TSUKAMOTO)
Based on the first beam experience in May, we performed
major improvements such as installation of wide-aperture
beam pipes and semi-remote vacuum equipment, as well as
re-alignment of magnets during the summer shut-down. With
all those countermeasures, we were ready for the next beam
by Oct.13. During the second beam period from October to
December, we carried out beam commissioning with higher-
intensity beam of typically 20kW. We also tried 50kW-equivalent
beam power operation for a short time without significant beam
loss. The OTR (Optical Transition Radiation) monitor
successfully measured the beam profile with a Ti-foil with 50kW
intensity. These are very encouraging results toward yet higher
beam intensity. In the winter shut-down, we installed a
collimator to be prepared for beam power of more than 100kW.
The primary proton beam line is now ready for the beam.
After the installation of the 2nd and 3rd horns into the
helium vessel, the vessel was evacuated before filling with
helium gas. Small vacuum leaks were observed, but were confirmed
to be no problem for the operation by measuring the oxygen
contamination after filling with 1500 m3 of helium gas into
the vessel in November.
Then, the test operation of the horns started. A small
discharge was observed somewhere in the helium vessel, but it
could be overcome by modifying the voltage level of the horn
electrodes. Then, three horns were successfully operated during
the 20 kW beam run in December. In the continuous beam operation
at 20 kW, the radiation level in the air in the surface building
(NU3) over the beam dump became not-negligible, and it limited
the beam operation time. Some air-leaking points from
underground rooms in NU3 were found and are being closed now
in order to have more continuous beam operation in the future.
The commissioning and calibration of the on-axis near
detector INGRID was carried out after the installation in August;
then it operated for the neutrino beam from November.
Sub-detectors of the near detector, the P0D (Pi-zero Detector),
the FGD (Fine Grained Detector), and the DSECAL (Down Stream
Electromagnetic CALorimeter) were installed in the Basket which
is sitting in the magnet and the off-axis detector operated for
the neutrino beam also from November. INGRID observed the
first neutrino event on November 22 and Following this
observation the off-axis detector also observed a neutrino
event on December 19.
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4. [Materials and Life Science Division] by Yujiro IKEDA
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THE WORLD STRONGEST NEUTRON PULSE WAS PRODUCED
THE USER OPERATION FOR 2008B PERIOD HAS BEEN STARTED
THE WORLD STRONGEST PULSED MUON BEAM WAS ACHIEVED
AT J-PARC MUSE ON THE NOVEMBER, 2009 BEAM CYCLE
1. Neutron Source
In the 300 kW high power operation in December 2009,
the world record in pulse neutron intensity among spallation
neutron sources in the world was achieved probably.
The number of cold+thermal neutrons below 0.4 eV leaking
from the coupled moderator surface for each pulse is
estimated to be 5E12 n/sr/pulse. This value amounts
to a neutron flux of 5E6 n/cm^2/pulse at 10 m from the
moderator without a neutron guide tube.
International workshop on pulsed spallation neutron
sources was held on 9th to 12th Nov. 2009 at J-PARC center
and in parallel the satellite workshop on cavitation damage
mitigation technology for mercury target on 11th and 12th.
It was a good timing for SNS/US and JSNS/J-PARC to discuss
on the common issues that they noticed through experienced
operations, and for the European Spallation Source and the
China Spallation Neutron Source to learn for their expecting
facilities.
2. Neutron Science
User operation for the 2009B period (the second half
of FY2009) has been started on Dec. 18. 61 accepted general
proposals for 8 neutron instruments are being carried out
during the period before the end of March. The High-
Performance Neutron Reflectometer with a Horizontal Sample
Geometry (BL16) has newly accepted general users from this
period. 4 instruments are under on-beam commissioning.
The 120 kW stable operation has inspired both instrumental
scientists and users. Experiments with small-size samples and/
or higher resolution experiments, etc., which cannot be carried
out with 20 kW, have been started. The 120 kW operation also
resulted in the increase of users from December as well as
the speed-up of commissioning for the 4 instruments under
commissioning.
A completion ceremony for the High Intensity Chopper
Spectrometer (4SEASONS, BL01) was held at the MLF on
December 25. The feature, construction process, software
development, and scientific goal of 4SEASONS were explained
in the ceremony. The ceremony finished with a group photograph
of about 60 participants stood on the shield of 4SEASONS.
3. Muon Science
By undergoing the beam tuning at the D2 area, we were able
to extract, at present, surface muons (positive muons) rate of
1.7E6/s with use of 120 kW of proton from RCS, which is
calibrated to be 1.5E7/s surface muons when future proton beam
reached at the intensity of 1MW.
Even at the D1 area, we observed 0.3E6/s of the decayed
positron with use of a collimator with a hole of 40 mm in
diameter, with use of the 300 kW of proton from RCS, which was
calibrated to be 1.2E7/s surface muons when future proton beam
reached at the intensity of 1MW.
These intensities, at the future 1 MW operation, will
correspond to more than ten times those at the RIKEN/RAL Muon
facility.
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5. [Exotic Nuclear Science Group] by Hiroari MIYATAKE
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A COMPACT TWO-GAP PRE-BUNCHER WAS NEWLY INSTALLED
UPSTREAM OF THE LINAC OF THE TOKAI RADIOACTIVE ION
ACCELERATOR COMPLEX (TRIAC) FOR NUCLEAR ASTROPHYSICS
EXPERIMENTS
A brand-new pseudo saw-tooth wave pre-buncher with
non-pi mode has been developed and installed downstream of a
beam chopper. The pre-buncher has two gaps, to which two
rf-waves, being combined together into the saw-tooth for
beam-bunching, are respectively applied.
It makes it possible to bunch continuous beams to 2-4 MHz
pulsed beams with a width of less than 38 ns, which corresponds
to the acceleration frequency of the Split Coaxial RFQ linac
just downstream the buncher. A typical pulse width of the beam
after acceleration (1.1 MeV/nucleon) was achieved to have a
2 ns standard deviation at the target position 10m away from
the exit of TRIAC.
The beam chopper consists of 20 foil-electrodes with a
2 mm gap stacked vertically to the beam direction. The beam
particles of out-of-bunch phase are deflected by these
electrodes. The ratio of pulsed-beam particles to background
ones has been further improved by the beam chopper from the
order of 10^3 to 10^5 at the target position. This S/N-ratio
was almost constant, irrespective of the output energies
ranging from 0.17 to 1.1 MeV/nucleon. As a result, this
system bunched 40% of continuous beam particles, i.e.,
bunching gain was found to be 6.53.
The system will be utilized for the measurement of 12C
(alpha, gamma) reaction cross-sections at the stellar energy,
which is one of important reactions describing element-
synthesis in the evolution of massive stars. The improved
S/N-ratio is supposed to be good enough for cross-section
measurements at the 10 pb/sr level.
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6. [Nuclear Transmutation Section] by Hirofumi TSUJIMOTO
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INTERNATIONAL ADS WORKSHOP WAS ORGANIZED
A workshop related to Accelerator-Driven System (ADS),
"Accelerator-driven Transmutation System for European and
Asian Young Scientists and Engineers", was held on December
1-4 at Tokai-site of JAEA in cooperation with J-PARC,
Nuclear Science and Energy Directorate, and Nuclear
Technology and Education Center. This workshop was organized
as part of a research cooperation with the IP-EUROTRANS
project and JAEA, and also as a part of a training
course of the European Nuclear Education Network (ENEN) with
which the Nuclear Technology and Education Center of JAEA
has a cooperative relationship. It was opened for young
scientists in Asian and European countries, and there were 55
participants including 32 foreign participants from 15
countries. In the workshop, four lectures for research
fields related to ADS and research activities for ADS in
Japan, China, Korea, and Europe were provided. Moreover, 20
presentations from young participants were presented, and
important issues for ADS and international collaborations
were actively discussed. In a technical tour, the
participants visited MLF and Hadron Hall in J-PARC.
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7. [Safety Division] by Taichi MIURA and Hiroshi NAKASHIMA
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THE SAFETY INSPECTION OF THE HADRON EXPERIMENTAL
FACILITY SUCCESSFULLY CONDUCTED BY NUSTEC
The inspections of the Hadron Experimental Facility (HD)
were conducted successfully on December 16, 2009, by the
Nuclear Safety Technology Center (NUSTEC): the inspection
items were working conditions of emergency and interlock
signals from secondary beam lines (K1.8 and KL) and shielding
structures, and were measurements of ambient doses around
the radiation control areas and at the boundary of the
J-PARC facility.
The 8th Radiation Safety Committee of J-PARC met on
December 15, 2009, to discuss the application of HD. The main
change point is the enlargement of two secondary beam lines
in HD: K1.1BR and KL.
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8. [Information Sytem Division] by Atsushi MANABE
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HIGH SPEED NETWORK SINET SUPPORTS J-PARC EXPERIMENTS
The SINET3 information network (http://www.sinet.ad.jp/)
has linked the J-PARC Tokai site and the KEK Tsukuba site
with 1Gbps bandwidth since Oct. 2008. Thanks to the support
of the Japan National Institute of Informatics (NII) which
manages the SINET network, the link bandwidth was doubled
to 2Gbps just before the 2009 autumn RUN and in JFY2011 it
will be expanded up to about 10Gbps. J-PARC provides
computing resources of 1600 SPECint06 computing power,
150TBytes RAID disks and 2PBytes tape libraries in the KEK
Central computer system at the Tokai site. The link speed-up
of the two sites is expected to enhance the data analysis
for J-PARC experiments.
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9. [Announcement of Symposia and Meetings]
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1) NIAC (Neutron International Advisory Committee), Feb.24-26,2010
2) A-TAC(Accelerator Technology Advisory Committee), Mar.11-13,2010
3) IAC(International Advisory Committee), Mar.15-17,2010
4) MLF symposium, March 29-31, 2010 in Tokai
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10. [Editorial Note]
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Editorial Board:
Masatoshi ARAI (chair): masatoshi.arai@j-parc.jp
Fujio MAEKAWA: maekawa.fujio@jaea.go.jp
Nobuo OUCHI: ouchi.nobuo@jaea.go.jp
Shinya SAWADA: shinya.sawada@kek.jp
Toshifumi TSUKAMOTO: toshifumi.tsukamoto@kek.jp
English Editor: Dick MISCHKE mischke@triumf.ca
Secretary: Chikako KAIBARA kaibara.chikako@jaea.go.jp
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