NewsLetter #6.
Masatoshi ARAI
masatoshi.arai at kek.jp
Wed Oct 24 20:30:06 CDT 2001
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JAERI-KEK Joint (JKJ) Project Newsletter No. 6 October, 2001
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High Intensity Proton Accelerator Project proposed jointly
by the Japan Atomic Energy Research Institute (JAERI)
and the High Energy Accelerator Research Organization (KEK)
http://jkj.tokai.jaeri.go.jp/
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1. Recent Progress of the Joint Project between JAERI and KEK on High-
Intensity Proton Accelerators (Shoji NAGAMIYA)
2. Report from the Accelerator Group (Yoshishige YAMAZAKI)
3. Report from the Nuclear and Particle Physics Experimental Facility
(Jun IMAZATO)
4. Report from the Neutron Science Group (Yujiro IKEDA)
(Materials & Life Science Experimental Facility Group)
5. Report from the Muon Science Group (Yasuhiro MIYAKE)
6. Report of the Exotic Nuclear Beam Science Group (Hiroari MIYATAKE)
7. Report from the Accelerator Driven Transmutation (ADS)
Experimental Facility Group (Hiroyuki OIGAWA)
8. Announcement of Workshop
9. Editorial note
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1. Recent Progress of the Joint Project between JAERI and KEK on High-
Intensity Proton Accelerators
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by Shoji Nagamiya
This time, there are a few items to report in relation to the
Local and Central Governments. In July, 2001, the Local Village
officially agreed to the construction of our facility. With this
approval, practical geological studies before the actual construction
of the tunnels and buildings were initiated in the summer.
The summer is a busy season for the project team to appeal for
the next year's budget. Although the actual decision on the budget
for JFY02 will be made at the end of this calendar year, a preliminary
indication from the Government is not unreasonable for this project.
Currently, the project team is working on many details: finding
places to store soils, deciding on methods for making roads and a bridge,
preparing the Agreement document on safety for the Ibaraki Prefecture,
and preparing a petition on cutting trees, etc. etc. These are not items
to report in detail in the Newsletter. However, most of our time has
been used for these activities.
An important item of news is that the ion-source group attained
72 mA while the design value was 60 mA. Another piece of good news is
that the 50 GeV group completed the field mapping test and, then, signed
a document for the massive purchase of the 50 GeV magnets. The design
team of the 3 GeV ring conducted lengthy discussions, and this team is
now finalizing the lattice design as well as other related construction
design. These are the areas of significant progress during the past
three months. See the article below for details.
The management team plans to have the first "Users Committee"
meeting soon. The name of the accelerator complex has not been
decided. We extended the deadline of applications to October 31,
2001. Please try to suggest a nice nickname or acronym for our
future facility.
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2. Report from the Accelerator Group
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by Yoshishige YAMAZAKI
The 3-GeV ring lattice has been recently optimized in order to
ensure more margin for the beam intensity. First, we have increased the
circumference by a factor of 10/9 to make more space available for the
beam position monitors and steering magnets. Second, we minimized the beta
function at the bending magnets to maximize the beam emittance,
keeping the same size for the bending magnets. The incoherent tune shift
now becomes - 0.16, assuming a bunching factor of 0.41, which will be
possible with the second harmonics field. The bidding of all the major
magnets for the 50-GeV ring was finished. Now, the production of these
magnets will be started. The Medium Energy Beam Transport (MEBT) of the
linac (at 3 MeV between the RFQ and DTL) was installed, while the chopper
is under conditioning. The commissioning of the MEBT will be started soon.
Several problems to be solved have been identified for the following
components, which are in the R&D phase.
1) The development of the 3-GeV ring bending magnets: This big magnet
must withstand a rapidly cycling magnetic field. A shorting problem
happened between the coils of the R&D bending magnet of the 3-GeV ring
during the rapid cycling excitation test.
2) The development of the klystron: Gun oscillation was observed in the
972-MHz klystron for the high-energy proton linac.
3) The development of the annular-ring coupled structure: A side coupling
cell is located between the end cell and bridge coupler. A vacuum leak
was found between the side coupling cell and the end cell.
The causes of these problems are now under investigation.
The 10th Workshop on RF Supercondutivity was held in Tsukuba from
September 6 to 11. The workshop was hosted by both JAERI and KEK and was
chaired by S. Noguchi. The electropolishing technology developed at KEK
has now become the world-standard owing to the efforts of K. Saito et al.,
which was especially highlighted in the summary talk by H. Padamsee.
This technique will be fully employed for our project also.
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3. Report from the Nuclear and Particle Physics Experimental Facility
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by Jun IMAZATO
One of the issues in constructing a high-current beam facility is
the design of the beam tunnel and beam line elements that will allow
maintenance work in a high radiation environment. Therefore, the
conceptual design of the tunnel structure and routing of utilities are
very important. In order to visualize the spatial constraints and to
check the ease of work around magnets to disconnect and connect wiring
and piping, etc., a mockup of the experimental hall tunnel was setup using
concrete shielding at KEK. At the moment a typical bending magnet has been
installed there and all necessary parameters are being investigated in
practice. The prototypes of other elements such as the target and beam
monitors will also be tested in this tunnel mockup before going into
real production.
The design of a target for secondary beam production is also
underway at KEK. To accommodate the very high energy deposition
corresponding to the maximum allowed beam loss of 30% of the full
760kW proton beam, a rotating target with water cooling as has been
adopted for the BNL g-2 experiment and at FNAL appears to be the most
promising choice. The construction team is now working on the heat
transfer analysis, the design of a rotation mechanism, and a water
cooling system by conducting model experiments. The treatment of
activated air in the surroundings and tritium production in the
cooling water is also being investigated.
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4. Report from the Neutron Science Group
(Materials & Life Science Experimental Facility Group)
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by Yujiro Ikeda
Short-term milestones towards the construction of the experimental
facility were set at the beginning of the project group formation as
follows; by the end of September, 2001, all of base parameters are to be
fixed for the design guide to prepare a conceptual design report (CDR), by
the end of December, 2001, parameters for the detailed engineering design
are to be confirmed, and by the end of March, 2002, the specification order
for detailed design is to be completed, and some fabrication of parts will
be started. The conceptual design of the target vessel structure has been
finished based on thermal stress analysis and hydraulic study of cooling
mercury. A double walled safety hull with water jackets of heavy water is
planned to cover the mercury target to ensure the safety of the target.
The structural strength of the safety hull is under analysis. Major design
base parameters for cold moderators and reflectors have almost been fixed
based on the neutronics analyses. Target remote-handling demonstration
tests using a gantry robot with a 6-axis powered manipulator and master
slave manipulators are being conducted now.
To carry out its function of interfacing between target-station
engineering and instruments development, the neutron beam-line & device
group is intensively working on the conceptual design of neutron beam
shutters, target-vessel windows (in relation to guide- and collimator
-inserts), and moderator. An instrument layout, which is under study in
parallel, is also being taken into account. Neutron beam-line shielding
calculations are underway and the first-round design has been completed.
We are also developing key components of the neutron scattering
instruments, like He-3 gas micro-strip counter systems, scintillation
detector systems, various neutron optical devices, and He-3 neutron
polarizer/analyzer system using spin-exchange method. A preliminary layout
of neutron instruments has been determined for the conceptual design study
of materials & life science experimental facility. The number of
instruments to be utilized for the purpose of science and industrial
applications is about 25.
The structure of a proton beam line inside the experimental facility
had been studied intensively with regard to activation of the air, NOx
formation, and airflow around beam line components. A basic concept has
been established and the technical design is proceeding. According to a
recent revision of the beam lattice of the 3-GeV synchrotron, which
resulted in a significant increase of the extracted beam emittance, the
beam optics of the whole transport line, magnets, power supplies and even
the beam line tunnel have been redesigned. Also, the main factors that
cause the beam to deviate from the center of the beam line are under
detailed study.
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5. Report from the Muon Science Group
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by Yasuhiro MIYAKE
A new PC cluster dedicated to calculations of radiation in the
vicinity of the muon production target and its duct-streaming along the
secondary beam line was built by Naritoshi Kawamura. A decay muon beam line,
which is one of the secondary muon beam lines, is modeled. It will extend
in the forward direction at an angle of 60-degree with respect to the
primary 3 GeV proton beamline.
To evaluate the duct-streaming or radiation shield along the
decay muon beam line, conventional formulas for evaluating radiation
are not applicable. A more sophisticated method of evaluation with
Monte-Carlo codes, NMTC/JAM, MCNP, and MCNPX is needed, although it
requires tremendously high performance in computing.
The PC cluster is composed of one master server with a 1.4 GHz Athlon
processor and 9 slave machines with 1.2 GHz Athlon processors. Its
performance is effectively about 50 times faster than a 700 MHz Pentium III
processor machine. At present, the cluster provides enough computing
power for our calculations.
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6. Report of the Exotic Nuclear Beam Science Group
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by Hiroari MIYATAKE
As reported before, KEK and JAERI have jointly started to construct
the KEK-JAERI Radioactive Nuclear Beam (RNB) Facility at the Tandem
accelerator of JAERI at the Tokai campus in FY2001. This facility is based
on the isotope separator on-line (ISOL) and post acceleration scheme and
has a potential to supply a heavy neutron-rich RNB with an energy of 9
MeV/u.
Several R&D projects, including the construction of the Charge
Breeding Electron Cyclotron Resonance Ion Source (CB- ECRIS), modification
of the frequencies of existing linacs, and development of the target-ion
source system, have been done. The CB-ECRIS will breed in flight those
charge states of ions from ISOL to inject them into the post linacs. The
trapping process of ions in an electron cyclotron resonance plasma has been
studied with a realistic simulation code and with the test bench from last
year. A newly designed 18 GHz CB-ECRIS is under construction and will be
installed at the end of this year.
Resonant frequencies of the heavy ion linacs (the split coaxial RFQ
linac and the interdigital H-type linac) will be modified by 2% in order to
connect them with the superconducting linacs as a tandem booster. A study
of how to change the resonant frequencies of these cavities has been done
by an equivalent circuit analysis, a computer code, and using a cold model.
Another R&D project on the production target-ion source system has been
started to keep stable operation and the safe replacement of the
uranium-carbide target.
A utility hut for housing the cooling water system and electronic
power supplies will also be constructed this year.
The semi-annual meeting on "The Science of the Low-Energy Radioactive
Nuclear Beams 2001" was held at KEK on Mar. 12-14, 2001 to exchange
information on recent studies and technical developments. About 80
scientists got together to discuss 30 reports, which include the nuclear
reaction mechanism near the barrier, the clustering feature of exotic
nuclei, relativistic effects of trans-actinides, the nuclear deformation,
material science by means of RNB probes, and technical developments
for RNB production.
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7. Report from the Accelerator Driven Transmutation (ADS)
Experimental Facility Group
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by Hiroyuki OIGAWA
As a part of the research and development for the ADS Target Test
Facility, a tube specimen of SUS316(stainless steel), which is a candidate
for the target vessel and primary coolant structure of the facility, was
dismantled from the loop after 3000 hours of operation to test corrosion of
the material. The liquid Pb-Bi was controlled to keep a temperature of 450C
at a flow rate of 0.5 - 1 m/s in the testing area. The cross section of
the specimen shows the surface was corroded/eroded locally. Detailed
inspections are under way.
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8. Announcement of Workshop
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International Workshop on Nuclear and Particle Physics
Experiments at 50-GeV PS, December 10-12, KEK
Correspondence: Dr. T. Nagae
E-mail: nagae at post.kek.jp, Fax: +81-298-64-5258
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9. Editorial note
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Editorial Board:
Masatoshi ARAI (chair): masatoshi.arai at kek.jp
Koji YOSHIMURA koji.yoshimura at kek.jp
Yujiro IKEDA: ikeda at cens.tokai.jaeri.go.jp
Nobuo OUCHI ouchi at linac.tokai.jaeri.go.jp
Shinya SAWADA: shinya.sawada at kek.jp
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