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J-PARC Project Newsletter
No.71, July 2018
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]
J-PARC MOVES TO A NEW STAGE OF OPERATION.
2. [Accelerator Division]
STABLE OPERATION AND 1 MW DEMONSTRATION OF THE ACCELERATORS.
3. [Particle and Nuclear Physics Division]
DETAILED STUDY OF A HEAVY HYPERNUCLEUS, 19-LAMBDA-F.
T2K HAS DOUBLED ANTI-NEUTRINO DATA AND RELEASED PRELIMINARY
ANALYSIS.
STATUS OF THE MUON G-2/ ELECTRIC DIPOLE MOMENT (EDM).
STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET).
4. [Materials and Life Science Division]
STEADY NEUTRON PRODUCTION OPERATION IS CONTINUING WITH PROTON BEAM
POWER AT 500 KW.
REACHED THE WORLD'S HIGHEST POWER LEVEL PER ONE PROTON BEAM PULSE.
285 NEUTRON GENERAL PROPOSALS HAVE BEEN RECEIVED FOR THE 2018B
PERIOD.
INFLUENCE OF COSMIC-RAY MUONS TO MICROCHIPS IN FOCUS.
5. [Nuclear Transmutation Division]
MEASUREMENT OF DISPLACEMENT CROSS SECTION FOR PROTONS.
6. [Safety Division]
FY2018 SAFETY DAY AT J-PARC.
7. [Editorial Note]
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1. [Overview] by Naohito SAITO
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J-PARC MOVES TO A NEW STAGE OF OPERATION
Now we are in the middle of the summer maintenance.
Before this break, we were able to make significant progress
in our operation from both technological and organizational
viewpoints.
As a technological achievement, we have successfully
demonstrated stable operation of the Materials and Life Science
Experimental Facility (MLF) for one hour at 1MW, which is yet another
J-PARC-wide teamwork including accelerators, targetry, beamlines,
and safety work. As we have been reporting in past newsletters,
we have been upgrading the beam power exposed onto two target
systems, a mercury target for neutron production and the graphite
target for muon production, step by step, from 300 kW to 500 kW in
Fast eXtraction (FX) mode and 525kW in Slow eXtraction (SX) mode
after the last summer shutdown. (Number of beam prtons available for
MLF depends on how much portion of protons from LINAC/RCS are
extracted to FX/SX via, ie. more protons are extracted to FX than
SX.)
Through this process, we have accumulated confidence on the high-
power operation from various viewpoints: the beam acceleration and
its transport with minimal beam loss, heat and shock management on
the target vessel, and the radiation level at the experimental hall.
And on July 3, we exposed a 1 MW beam onto the two target systems at
the MLF. The temperature rise measured at several locations in the
target systems, vibrations measured on the mercury target system, and
the radiation level measured at the experimental hall were fully
consistent with the expected values.
In addition, the Main Ring (MR) operation was successfully
improved in its power and stability in both Fast eXtraction (FX) mode
and Slow eXtraction (SX) mode, at 490 kW and 51 kW, respectively.
These successes opened the door to the J-PARC operation at its full
capacity at all facilities.
In parallel with these technological advancements, we were under
governmental review, which has been held every five years for big
projects like J-PARC. The scope of the review was to assess the
progress since the last review held back in 2012, which recommended
the enhancement of competence in research activities at J-PARC. More
specifically, more science driven directions at MLF and machine
improvements at the Main Ring (MR) were raised as key issues. Our
responses have been positively received by the review committee
chaired by Dr. Kikuchi from Toyota Central Laboratory including near
future upgrade plans. Among several suggestions by the committee,
they also encouraged that J-PARC should proceed to build a concrete
plan for open-access to the J-PARC site. We, the J-PARC Center, will
accelerate the planning process with the relevant stakeholders.
We will be waiting for the users to come back for the autumn-to-
winter beam operation of J-PARC, which has now entered a new stage of
beam-power at all facilities!
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2. [Accelerator Division] by Kazuo HASEGAWA
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STABLE OPERATION AND 1 MW DEMONSTRATION OF THE ACCELERATORS
We delivered beam from January as Run#78 until the morning of
April 2 as scheduled. After the replacement of the ion source and
short maintenance work, we started new Run#79 from April 4. We
delivered beams for the user operation of the Materials and Life
Science Experimental Facility (MLF) at the beam power of 400 kW, and
the beam power was increased to 500 kW on April 19.
The Main Ring (MR) delivered beams to the neutrino Experimental
Facility (NU) at about 480 kW until May 31. Then we switched the
extraction mode from fast to slow and started tuning for the Hadron
Experimental Facility (HD). We smoothly ramped up the power to 51 kW,
which exceeded the previous power of 37 kW in June 2017 and recorded
a new power level.
The user operation ended in the morning of June 30, which was
extended by 17 hours from the original schedule. The availability
from April to June for the MLF, NU and HD was generally good at about
93%, 86%, and 88%, respectively. We had an accelerator study time
until noon of July 4 and stopped the operation for the summer
shutdown. During the study time, we successfully demonstrated 1 MW
equivalent (8.3x10^13 protons per pulse) and one-hour duration
operation for the MLF. The first time of the 1 MW demonstration was
in January 2015 and it was only the single shot operation. We
advanced the operation experience toward the design goal of J-PARC.
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3. [Particle and Nuclear Physics Division] by T. TAKAHASHI,
T. ISHIDA, T. MIBE, AND S. MIHARA
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DETAILED STUDY OF A HEAVY HYPERNUCLEUS, 19-LAMBDA-F
(by T. TAKAHASHI)
The study of a heavy hypernucleus, which contains strange quark
baryons in the nucleus, attracts wide interest for understanding
general characteristics of Baryon-Baryon interactions. Especially,
the level structure of a relatively heavy hypernucleus is important
to have crucial experimental information about nuclear matter.
The J-PARC E13 experiment was carried out in June 2015 at the
K1.8 beamline to measure the level structure of the 19-Lambda-F
hypernucleus by gamma-ray spectroscopy. The 19-Lambda-F hypernucleus
was generated by irradiating a liquid CF4 target with a 1.5 GeV/c
negative kaon beam and was identified by an outgoing negative pion
with a spectrometer system. In the E13 experiment, gamma rays emitted
by level transitions of a 19-Lambda-F hypernucleus were measured.
De-excitation gamma rays were identified coincidentally by Ge
detector arrays and the Hyperball-J detector. Four gamma rays of 316,
895, 953, and 1266 keV were well observed and were assigned level
transitions among three excited levels.
The gamma ray of 316 keV is assigned to a M1 transition from a
3/2+ state to a 1/2+ state. The energy difference between these two
states is related to a spin-spin interaction between a Lambda in
s-orbit and nucleons at the outermost orbit. Thus, new experimental
data with heavier hypernucleus gave an additional information to
Lambda-Nucleon interactions in larger radial region. The energy level
of 316 keV is in good agreement with the theoretical model
calculation, which is established with light hypernuclear data using
spin-dependent Lambda-Nucleon interactions. This result was published
recently in Phys. Rev. Lett. 120, 132505.
T2K HAS DOUBLED ANTI-NEUTRINO DATA AND RELEASED PRELIMINARY ANALYSIS
(by T. ISHIDA)
The T2K experiment has successfully completed its data taking
before the summer shutdown on May 31 as scheduled. This time of data
taking was mostly in the anti-neutrino mode, which the total amount
of protons on target (pot) in the anti-neutrino mode reached 1.65 x
10^21. It more than doubled the pot before 2017, and is now
comparable to those in neutrino mode, 1.51 x 10^21 pot.
Preliminary analysis results based on about 1.5/1.1x10^21 pot
for neutrino/anti-neutrino mode data were released at the Neutrino
2018 conference. The observed number of anti-nue appearance events is
nine in total while the expectation is 11.8 events, including 6.5
background events. At this stage, the anti-nue appearance signal
excess over the background is not yet conclusive. Analysis shows that
CP conserving values of δCP lie outside the 2σ region as
was the case mentioned last summer.
Between the two possible mass orderings, the normal mass ordering is
preferred with a posterior probability of 89 percent.
STATUS OF THE MUON G-2/ ELECTRIC DIPOLE MOMENT (EDM) (E34)
(by T. MIBE)
The E34 collaboration prepares for precision measurements of the
muon anomalous magnetic moment and electric dipole moment. The
collaboration received a report from the review committee under the
Program Advisory Committee (PAC). This review was focused on
Technical Design Report (TDR) updated in December 2017.
Construction of the surface muon beamline (H-line) is in
progress. Data on the cross calibration of magnetic field measurement
that was probed at J-PARC and Fermilab g-2 was collected with an MRI
magnet at Argonne National Laboratory at the end of March. This will
correlate the field measurements in both experiments.
A paper on the first muon acceleration using a radio-frequency
accelerator was published as Phys. Rev. Accel. Beams 21, 050101
(2018). Another paper on the development of a microchannel plate
based beam profile monitor for a re-accelerated muon beam was
published as Nucl. Instr. and Meth. A 899, 22 (2018).
STATUS OF THE COHERENT MUON TO ELECTRON TRANSITION (COMET)
(by S. MIHARA)
The COMET experiment aims to search for the lepton-flavor
violating muon reaction, mu-e conversion, with sensitivity better
than 10^{-14} in Phase I.
After successful proton beam acceleration and extraction tests
for the COMET experiment in January and February 2018, further study
of a new beam monitor using a diamond as a sensor is in progress.
Radiation tolerance of this monitor is investigated by irradiating
proton beam on it at the Main Ring abort line.
Construction of detectors for both physics and beam measurements is
in progress at KEK. Intensive studies of the main detector for the
physics measurement, the CDC, are conducted using cosmic-ray muons.
The collaboration had its 25th collaboration meeting at J-PARC
in May. Progress of facility and sub-detector construction status was
reported, and future schedule was discussed. At this meeting, the
collaboration board officially approved participation of two new
groups from Laboratoire de Physique Corpusculaire, Caen, France and
Institute of Nuclear Physics, Ministry of Energy, Kazakhstan.
The collaboration is now composed of 37 institutions from 18
countries.
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4. [Materials and Life Science Division] by Toshiji KANAYA
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STEADY NEUTRON PRODUCTION OPERATION IS CONTINUING WITH PROTON BEAM
POWER AT 500 KW
REACHED THE WORLD'S HIGHEST POWER LEVEL PER ONE PROTON BEAM PULSE
1) Neutron Source
On April 19, 2018, the proton beam power delivered to the
neutron-producing mercury target was increased from 400 kW to 500 kW.
Current mercury target vessel had been redesigned to have enough
structural strength for the beam power higher than 500 kW on the
basis of the cause analyses of the failures that occurred on the
previous target vessel in 2015. At the beginning of the power ramp-
up, we measured the temperature at a critical portion on the mercury
vessel where the highest stress was expected to be induced by the
proton beam injection. It confirmed that the resultant temperature
was much lower than the allowable value even if profile and/or
position of the proton beam changes in a possible range. The mercury
target system has successfully been providing neutrons with
availability of 92% at 500 kW to date.
At Oak Ridge National Laboratory, the mercury target of the
Spallation Neutron Source (SNS) had been in operation with a proton
beam power from 1 MW to 1.2 MW with the repetition period at 60 Hz.
At J-PARC, the repetition period of the proton beam pulse is 25 Hz
with the proton beam power of 500 kW. Taking into account the
difference in those repetition periods, the power per one proton beam
pulse injected onto the mercury target at J-PARC has reached the
world's highest level even at the proton beam power of 500 kW.
285 NEUTRON GENERAL PROPOSALS HAVE BEEN RECEIVED FOR THE 2018B
PERIOD
2) Neutron Instruments and Science
Call for General proposals and New User Promotion proposals for
the 2018B period was closed on June 7 and we received 285 neutron
proposals. Those proposals will go through the Neutron Science
Proposal Review Committee / Proposal Evaluation Committee (NSPRC/PEC)
for reviewing process. Users will be informed of the final results in
September.
In addition to these regular schemes, General proposals for Long
Term proposal program (LTP) starting from 2018B with three-year
validation were also called. We received nine proposals. Five of these
proposals were selected to the next examination for hearing in the
Sub-Committee /Expert panel. The review results will also be sent to
the NSPRC/PEC.
The first half of the user program for the 2018A period ended in
the morning of June 29. The second half of 2018A period will be
resumed from October 22.
INFLUENCE OF COSMIC-RAY MUONS TO MICROCHIPS IN FOCUS
3) Muon Science Facility (MUSE)
The modern information technology based on microchips has become
an indispensable commodity in our daily life. This means that there
is the chance of some disaster associated with faulty operation.
Among many potential causes of such a fault, the single event
upset (SEU) induced by cosmic-ray radiation has become a recent
focus. The primary component of the cosmic rays is muons. In order to
make an experimental assessment on this issue, a collaboration group
of Kyushu-U, KEK-IMSS, Osaka-U., and JAEA have performed an
irradiation test of low-energy positive and negative muons on a 65-nm
ultra-thin body and thin buried oxide silicon-on-insulator (UTBB-SOI)
SRAMs.
The SEU cross sections were measured systematically as a
function of incident muon momentum and operating supply voltage. The
experimental results show that the negative muon SEUs occur at about
three times higher rate than the positive muon ones at the supply
voltage of 0.5 V when the incident muons stop near the sensitive
volume.
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5. [Nuclear Transmutation Division] by Shin-ichiro MEIGO
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MEASUREMENT OF DISPLACEMENT CROSS SECTION FOR PROTONS
Displacement per atom (DPA) is a damage index for materials,
which is estimated by displacement cross section and particle flux.
It is widely applied not only in accelerator facilities but also
in fission and fusion reactors. Nevertheless, the displacement
cross section for a proton in the kinematic energy range above 20 MeV
had not been measured. For the accurate damage estimation of
structural material such as the beam window utilized in the
accelerator-driven system (ADS), the displacement cross section was
measured for copper irradiated with 3-GeV protons.
The displacement cross section can be obtained from the resistivity
change of the sample due to the irradiation with protons under the
cryogenic condition. To carry out the experiment, we installed the
vacuum chamber with the cryocooler at the 3-GeV proton synchrotron
facility in J-PARC, where the energy of protons from 0.4 to 3 GeV is
available.
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6. [Safety Division] by Yukihiro MIYAMOTO and Kotaro BESSHO
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FY2018 SAFETY DAY AT J-PARC
The J-PARC Center sets "the Safety Day" around May 23 on which
the radioactive material leak incident occurred at the Hadron
Experimental Facility in 2013. The Safety Day in FY2018 was held on
May 25.
In the morning at the day, a meeting for exchanging information
on safety efforts was held. Some good-practices were awarded by the
director. Furthermore, a scientific talk on safety and good
activities concerning mitigation of tritium discharge at MLF and
electrical safety at MR were presented in the meeting.
In the afternoon, the 5.23 Workshop for Fostering Safety Culture
was held. The main talk entitled "Ensuring safety in automated
manufacturing processes and construction of safety culture at Toyota"
was given by Mr. Haruyasu Hoshino, Toyota Motor Corporation. Further,
a video record on the radioactive material leak incident was shown,
and a talk on the incident was given.
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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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