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We designed an impedance tuner consisting of an inductive material, FINEMET, to cancel the space charge impedance in the longitudinal direction. It was installed in the KEK Proton Synchrotron (PS) main ring. We observed the frequency shift of the coherent quadrupole oscillations and inferred the shift of the incoherent synchrotron oscillation. The total reactive impedance can be estimated as the coefficient between the shift and the beam intensity. The measured impedance is reduced from −j2475Ω to −j1182Ω by the impedance tuner which consists of 12 pieces of FINEMET cores. We demonstrated that the space charge impedance is compensated by the impedance tuner. This is the first time for FINEMET to be equipped with an accelerator component. One may think that the characteristics of FINEMET deteriorate under an environment with strong radiation generated by unavoidable beam loss. We have proved that the radiation dose not affect FINEMET even with a total neutron dose of 1.83×1012(n cm−2), which is considered ...

We studied the beam loading effects on the High Gradient Cavity (HGC) loaded with Magnetic Alloy (MA) by multiparticle tracking simulation. The Q-value of the cavity is variable from 0.6 to more than 10. From the view point of multi-bunch effect, it was found that either very high Q-value or low Q-value was preferable to suppress the periodic transient beam loading. The experimental results of the beam loading compensation using an electron beam are also described.

A high gradient cavity (HGC) using high permeability magnetic alloy (MA) cores has been developed at KEK for the JHF (Japan Hadron Facility) proton synchrotrons. In this paper, we describe two types of push-pull amplifiers to drive the cavity, which were constructed for verifying the cavity performance. An accelerating voltage of 20 kV across the gap of the HGC was generated by the high power push-pull amplifier. This is equivalent to high gradient field of 50 kV/m. The other amplifier and the cavity were prepared for accelerating heavy ions at the HIMAC (Heavy Ion Medical Accelerator in Chiba). For this purpose, it is necessary to sweep the frequency over the wide range from 1 MHz to 8 MHz.

Very high field-gradient has become available by a new magnetic alloy (MA)-loaded cavity developed for high intensity proton synchrotrons. The available RF voltage per core is ten times larger than that of the ordinary ferrite core. The maximum voltage of 20 kV has been achieved by the high-field gradient cavity (HGC) of 40 cm in length. Because the intrinsic Q-value of the MA core is low, acceleration without any tuning system also becomes possible. The first beam acceleration test using the HGC has been performed successfully at the HIMAC (Heavy Ion Medical Accelerator in Chiba). Furthermore, the dual harmonic RF and barrier bucket experiments have been carried out. Another advantage of the MA-loaded cavity is that it is easy to compensate the beam loading. The feed forward beam compensation was applied for both HGC on the test bench using an electron beam and MA-loaded cavity installed in the AGS for the barrier bucket experiment. A new development for high-Q HGC using a cut core configuration will be also reported.

The first beam acceleration test using a high gradient cavity (HGC) loaded with magnetic alloy (MA) cores has been carried out at the HIMAC (Heavy Ion Medical Accelerator in Chiba). Acceleration of heavy ions, which required a wide frequency sweep from 1 MHz to 8 MHz, was successfully carried out without resonant frequency tuning.

This paper introduces a new type of chopper, which is similar to a beam transformer first discussed by R. Wideroe (1928). It is based on the fact that the RFQ has a rather small energy window. A pulsed beam transformer that provides 10% energy modulation to the beam in front of an RFQ can effectively chop the beam. It has fast rise- and fall-time and a short physical length. A prototype, which consists of a cavity and a high voltage pulsed power supply, has been constructed and tested. Two types of magnetic materials were tried for making the core of the cavity-the Finemet and the ferrite Philips 4M2. While the former gave good performance, the latter failed the test. Results from the bench measurements and a plan for beam tests are briefly described.

In collaboration with KEK two barrier cavities, each generating 40 kV per turn have been installed in the Brookhaven AGS. Machine studies are described and their implications for high intensity operations are discussed.

A multi-orbit synchrotron (MOS) with fixed field alternating gradient (FFAG) focusing is attractive for acceleration of high intensity hadron beams because acceleration cycle could be increased. The magnetic field of MOS is static, therefore, the repetition rate of acceleration could be increased more than 10 times larger than that of ordinary rapid cycling synchrotron (RCS) if an efficient high voltage RF accelerating system becomes available. Recently, a new type of high gradient RF cavity (HGC) using high permeability magnetic alloy (MA) has been developed and MOS with FFAG focusing becomes very promising. In order to clarify the feasibility of rapid cycling MOS (RCMOS) experimentally, proof-of-principle (POP) machine, which accelerates protons up to 1 MeV with 1 kHz repetition, is under development. We have also made several designs on high intensity proton accelerators with RCMOS for various applications such as an accelerator driven system (ADS) as an energy breeder, a spallation neutron source and a proton driver for a muon collider.

A magnetic alloy (MA) loaded cavity which was developed by KEK was used for the barrier bucket experiment at the AGS. The MA loaded cavity could generate a single sine-wave of 40 kV with less RF power than a ferrite loaded cavity because of its broad-band impedance. In order to reduce the voltage induced by beam, the feedforward system was applied and the beam loading was compensated. With the barrier bucket scheme, five bunches were transferred successfully. Total of 3/spl times/10/sup 13/ protons were accumulated without beam loss. They were re-bunched by the accelerating cavities and accelerated.

We have succeeded in canceling longitudinal space charge effects using the 'impedance tuner' at the KEK-PS. The impedance tuner consists of the new material, 'FINEMET' which has large permeability over the beam spectrum region. A frequency shift of coherent quadrupole mode is measured to infer the modified impedance. It turns out that nonlinearity unavoidable in a longitudinal RF bucket has to be treated carefully in order to digest observed beam signals. We describe how to measure the impedance from the beam signal, how to analyze the effect of impedance tuner, and how to succeed in canceling space charge effects.

Fixed Field Alternating Gradient (FFAG) is a strong candidate for muon accelerators of the neutrino factory because fixed field allows essential fast acceleration for muon. Roughly speaking, we have two schemes to design FFAG optics, scaling and non-scaling [1]. Scaling FFAG has constant betatron tunes, in principle, with the magnetic field having nonlinear components. However, tunes slightly change during acceleration because of imperfection of the field. On the other hand, a condition of constant tunes is given up in non-scaling FFAG to obtain other advantages such as simple lattice composed of only linear elements. Then, beam dynamics of resonance crossing has become an important issue for both scaling and non-scaling FFAG. Since keeping constant tunes is basic strategy to avoid resonance, dynamics of resonance crossing has not been studied sufficiently. There are especially not many experimental studies. We performed beam studies of third order resonance crossing at PoP FFAG and HIMAC synchrotron. Their main results are described in this paper.

A project to develop the fundamental technologies for accelerator magnets using coated conductors is in progress. A coil-dominated magnet and an iron-dominated magnet were designed, based on the conceptual design of spiral sector fixed field alternating gradient accelerator for carbon cancer therapy and that for accelerator-driven subcritical reactor, respectively. The required winding technologies were clarified through designing the magnets. The R&D of winding technologies for coils with three-dimensional shape and those with negative bend have been carried out. The influence of the magnetization of coated conductors on the field quality of magnets was studied experimentally.

Recent developments in scaling fixed field alternating gradient (FFAG) accelerators have opened new ways for lattice design, with straight sections. An experiment to study zero-chromatic straight sections is in progress at KURRI.

Pressure effect on the structure of proteins and peptides has recently been studied theoretically and experimentally. Some proteins are denatured under high pressure conditions while some peptides are more stable in the folded state than in the random coil state at high pressure. It is important to understand the molecular mechanism of pressure-induced structural changes of proteins and peptides.We studied pressure effect on the structure of peptides by using molecular dynamics simulations. Molecular simulations often get trapped in the local minimum states of the free energy. In order to overcome such difficulty, we used a generalized-ensemble algorithm, which gives more efficient sampling in a molecular simulation.We performed molecular dynamics simulations with a generalized-ensemble algorithm for helical peptides in explicit water molecules. We found that the population of the secondary structure of the peptides changes as pressure increases. We also calculated the free energy as a function of pressure. The detail molecular mechanism of the structural change induced by pressure will be shown in the meeting.

Coil-dominated magnets wound with coated conductors were designed for an FFAG accelerator for carbon therapy, which was designed by applying linear approximation. When designing the coil-end of the magnets, we applied differential geometry. To apply the differential geometry to three-dimensional windings with coated conductors, we introduced the concept of generalized flat-wise bending. Thereby, the combination of flat-wise bending and torsion was considered as bending of developable surface. Generated magnetic field was calculated, and the positions of conductors were optimized to minimize the field error. Three dimensional shapes of magnets were successfully designed with constraints on generalized flat-wise bending and edge-wise bending of coated conductors.

Present status and future prospect of optically pumped polarized ion source (OPPIS) are described.

The acceleration of polarized protons in multi‐GeV machines is a great challenge for accelerator physicists. An essential part of such development is the primary source of polarized H− ions. Recent studies at TRIUMF and INR, Moscow, showed that pulsed Optically Pumped Polarized Ion Source (OPPIS) could produce up to 1.2 mA H− ion beam with polarization in excess of 80% within 1.5 π mm‐mrad normalized emittance. This current is ten times higher than the best currently available from atomic beam sources. The pulsed OPPIS is quite inexpensive in comparison with atomic beam source, and is ideally suited for high energy accelerator applications.

We present generalized-ensemble algorithms for isobaric–isothermal molecular simulations. In addition to the multibaric–multithermal algorithm and replica-exchange method for the isobaric–isothermal ensemble, which have already been proposed, we propose a simulated tempering method for this ensemble. We performed molecular dynamics simulations with these algorithms for an alanine dipeptide system in explicit water molecules to test the effectiveness of the algorithms. We found that these generalized-ensemble algorithms are all useful for conformational sampling of biomolecular systems in the isobaric–isothermal ensemble.

Direct fast H− beam chopping in a surface-plasma-type negative hydrogen ion source has been studied at KEK. The H− beam is chopped at several MHz by modulating the converter bias voltage of the ion source. However, in this case, a slow rise time of the chopped H− beam is one of the most serious problems for synchrotron injection. In order to make the rise time faster, a negative voltage was applied to the anode electrode. In the new scheme, mesh inserts were installed inside the ion extraction hole of the anode. Applying a retarding voltage on the meshes, the fast beam chopping was tested and the results are reported and discussed in the article.

The momentum dependence of the analyzing power ${\mathit{A}}_{\mathit{y}}$ in proton-proton elastic scattering has been measured in small steps using an internal target during polarized beam acceleration from 1 to 3 GeV/c. The momentum bin size ranges from 5 to 18 MeV/c. The relative uncertainty of ${\mathit{A}}_{\mathit{y}}$ is typically less than 0.01 for each momentum bin. Narrow structures have been found in the two-proton invariant mass distribution of ${\mathit{A}}_{\mathit{y}}$.

Negative ion sources based on plasma‐surface interactions (BLAKE ion source) have been developed at KEK for producing negative heavy ions. The first negative heavy ion source (BLAKE‐II) was developed by modifying the ordinary negative hydrogen ion source with converter (BLAKE‐I) placed into the plasma. It generates various species of negative heavy ions with intense beam currents. For example, a more than 10 mA Au− ion beam was obtained from the ion source. Recently, the large scaled negative heavy ion source (BLAKE‐III) has been developed and in the preliminary test experiment, more than 100 mA Cu‐ ion beam has been stably obtained with a 10% duty factor in pulsed operation. The BLAKE‐II ion source was attached to the BNL 15 MV and Tsukuba University TANDEM accelerators and large current negative heavy ion beams were successfully accelerated in pulsed mode operation. Also, it was found that the space charge effect should be carefully considered for such a large current acceleration in a tandem accelerato...

A pulse-operated polarized H− source of the Lamb-shift type has been developed at the National Laboratory for High Energy Physics in Japan (KEK) for future acceleration of polarized protons in the KEK 12 GeV proton synchrotron. A new spin selection principle proposed by Donnally has been adopted, in which only the hyperfine substate of 2 S 1 2 with zero total angular momentum is selected by causing the transitions of the other three substrates of 2 S 1 2 to 2 P 1 2 by an rf electric field making an angle of about 50° with the direction of a weak static magnetic field. In the preliminary experiments, a 350 nA H− beam of about 60% polarization has been obtained.

A polarimeter for the polarized proton beam has been constructed at KEK. The measurement of the beam polarization at 3.5 GeV was performed by the newly constructed polarimeter. Monitoring of the beam polarization during the experiment was successfully done by a polyethylene target. The present paper describes the structure, the characteristics and the results of practical use for the experiment.

The angular distributions of secondary electrons contained in a cascade shower are studied by using a streamer chamber ∗∗ . The primary electrons with energy of about 350 MeV are incident on a lead converter of various thickness. The angular data are analyzed for the number of electrons in a shower, and for the converter thickness. The obtained distributions show a systematic agreement with the Monte-Carlo calculations presented by Messel and Crawford.

Depolarization of the polarized proton beam accelerated in the 500 MeV booster was investigated as the first step of polarized proton acceleration in the KEK proton synchrotron. Beam polarization was measured in the 20 MeV beam transport line from the linac to the booster and in the main ring at the injection energy of 500 MeV. About 40 % of the linac beam polarization was kept in the main ring.

Acceleration of the polarized proton beam at the KEK PS up to 3.5 GeV is described. In the booster synchrotron, 75% of the linac beam polarization was preserved without any correction for the depolarizing resonances. In the main ring, almost 100% of the booster beam polarization was preserved at 3.5 GeV by the fast passage method for the intrinsic resonances and by the closed orbit correction for the imperfection resonances. The KEK PS is the first cascaded synchrotron which has demonstrated acceleration of a polarized beam.

The spin-exchange reaction between hydrogen atoms and optically oriented sodium atoms was used to produce a polarized atomic hydrogen beam. The electron-spin polarization of the atomic hydrogen beam, which underwent the spin-exchange reaction with the optically oriented sodium atoms, was measured. A beam polarization of −(8.0 ± 0.6)% was obtained when the thickness and polarization of the sodium target were (5.78 ± 0.23) × 1013 atoms/cm2 and −(39.6 ± 1.6)%, respectively. The value of the spin-exchange cross section in the forward scattering direction, whose scattering angle in the laboratory system was less than 1.0°, was obtained from the experimental results as Δσex=∫dσdωdωθlab=0 →1.0°=(3.39±0.34)×−15cm2. This value is almost seven times larger than the theoretical value calculated from the NaH potential. The potential was computed quantum mechanically in the space of the appropriate wave functions of the hydrogen and the sodium atoms.

Faraday rotation of optically pumped sodium atoms in a weak magnetic field, which is lower than the critical field of hyperfine splitting, was obtained theoretically. The estimated rotation angles were compared with the experiments for various magnetic fields. The measured values showed good agreement with the values calculated from the theory.

A number of silicon surface barrier detectors has been arrayed in mosaic structure to increase the sensitive area by an order of magnitude. It has been used as a remote detector at the end of the flight tube in the double-energy single-time-of-flight measurements of 252 Cf spontaneous fission fragments and found to be as good in performance as a small detector ordinarily used.

The analyzing power for elastic pd scattering at 3.5 GeV has been measured in the region 0.1⩽−t⩽1.5 (GeV/ c ) 2 , using the polarized proton beam at KEK. The angular distribution shows a behavior similar to that in the lower energy region. It is reproduced fairly well by the predictions of a multiple scattering model based on the Glauber theory.

Several O-ethyl O-p-nitrophenyl substituted phenylphosphonates were prepared and the effects of the substituent on the alkaline hydrolysis were studied.The rate of these phosphonates on hydrolysis were measured by detection of p-nitrophenoxide ion in a phosphate buffer at pH 8.3 at 45°C.The rate constants were calculated from the kinetic data.

有機リン殺菌剤イネジン(O-ethyl, phenyl-S-benzylthiophosphonate)の水稲体内における吸収,移行代謝分解の実験を行ない,次の結果が得られた. (1) ラジオオートグラフィー法の定性的な検討によると,局所塗布法による32Pイネジンまたはその代謝産物の移行性は小さく,薬剤は同一節内部でのみ移行し,上方へ移行する傾向が見られた.ただし,節間での移行は認められず,塗布部位の違いによる差,経時的な差も認められなかった. (2) 経根的に吸収させたイネジンは植物全体に移行する. (3) 稲体からの抽出物の大部分の放射活性はn-ヘキサン層に認められ,ヘキサン可溶物質は代謝されずに残ったイネジンとして同定された. (4) 70%メタノール抽出物は3～8日の間増加し,代謝産物としてエトキシフェニルチオリン酸,脱エチルイネジン,フェニルチオリン酸,エトキシチオリン酸を同定し,そのほかに未確認物質を1つ得た. X線フィルムによるラジオオートグラムと代謝物を定量した結果より,イネジンの主な分解過程はエトキシフェニルチオリン酸ができ,それがフェニルチオリン酸に代謝されていく経路である.次にイネジンが脱エチルイネジンに代謝され,それがフェニルチオリン酸に分解される過程も多いと考えられる.

Optically pumped polarized H- ion source has been developed at KEK. Various improvements have been made for stably long term operation. Among them, efforts were concentrated to develop a control system for pumping dye lasers with a personal computer and an ECR ion source. We also examine polarizing effect of dissociated hydrogen atoms from H2+ ions and show that it could be possible to use H2+ ions instead of H+ ions in this type of polarized ion source.

The effect of radiation trapping in an optically pumped sodium target was measured with a Faraday rotation method. The experimental results were compared with calculations based on recent theoretical work, and good agreement was found between the two.

Dc mode operation was tried in the cusp-magnetic-field negative heavy ion source, which has been successfully operated in the pulsed mode recently to obtain intense negative heavy ion beams. In a preliminary experiment, a dc beam of more than 1.5 mA for negative copper ions has been obtained easily at the relatively low are current of 3.5 A