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We report our studies in various fields of Physics through nuclear moments utilizing the β-NMR technique, including material sciences, nuclear structures and fundamental symmetries. Especially, we focus on the recent progress in the studies on the electronic structure in Pt through Knight shifts of various impurities, lattice locations of impurities, electric field gradients, the analysis of nuclear spin in terms of its components, anomaly in the spin expectation value for 9C-9Li mirror pair, the G-parity conservation law, and the Ramsey resonance on UCN for future neutron EDM measurements.

SAGA HIMAT [1], the fourth carbon ion beam therapy facility in Japan, is located in Tosu city, Saga prefecture (Figures 1 and 2). The SAGA HIMAT Project is a collaborative work among the local governments, regional industries, and medical societies in the Kyushu area. The initial cost of this facility was approximately ¥15 billion, which was covered by donations, investments, and local government aid. The facility is managed by a nonprofit organization, SAGA HIMAT Foundation. At SAGA HIMAT [2], carbon ions are accelerated to up to 70% of light speed by 2 linear accelerators and a synchrotron. The accelerated ion beams are transported to treatment rooms A and B. The range of extracted energy is 140 to 400 MeV/u (Table 1). Room A has horizontal and 458 oblique beam lines; room B has horizontal and vertical beam lines. Broad beams are used and each outlet measures 15 cm3 15 cm (Figures 3 and 4). In preparation for treatment, radiation technologists create an immobilization device customized for each patient placed on a mock treatment couch. Dose compensation boluses adjusted to the shape of the irradiation fields are designed from the computed tomography (CT) simulation data and produced by outside manufacturers. We also have a regular CT scanner and magnetic resonance imaging for diagnosis. Treatment room C is now under construction for pencil beam scanning therapy. SAGA HIMAT is a stand-alone outpatient clinic specialized for carbon ion cancer therapy. The patients initially visit a cancer treatment facility of their choice, receive a diagnosis and staging of the cancer, and are referred to our institution for carbon ion

A fast three-dimensional scanning irradiation method is under development at the Heavy Ion Medical Accelerator in Chiba (HIMAC) as the next stage of heavy ion cancer therapy. This method requires highly accurate control of the beam size, energy, and intensity. To improve the accelerated beam’s quality, a new scheme for the synchrotron RF system has been developed. The new system adopts a periodic time clock system (T-clock) instead of an ordinary B-clock system. The new T-clock system is synchronized with a power line frequency of 50 Hz for synchronization with the synchrotron power supply. An ordinary B-clock system results in error pulses owing to the small analog signal of the magnetic field of the main dipole magnet, and the errors cause dipole oscillation of the beam in the RF bucket. Using the new T-clock generator at 192 kHz, we have observed an improvement in the acceleration efficiency and bunch shape compared to the B-clock generator.

A systematic investigation on the longitudinal and transverse momentum (P_L and P_T distributions of projectile-like fragments (PLFs) produced at intermediate energies has been performed experimentally. The momentum distributions of PLFs in a broad range of mass and charge, produced from 290 MeV/u Ar- and Kr-beams with various targets (C, Al, Nb, Tb and Au), were observed. The analysis of P_L distributions with an asymmetric Gaussian function provides the deceleration effect and the width of the distributions with good precision. A definite systematics is found in both the deceleration effect and the width. The broader width obtained at the low-momentum side indicates the contribution of multi-step processes at this energy. The target and energy dependencies of the induced momentum width are also shown. The analysis of P_T distributions with an off-centered Gaussian function provides not only the width, but also the orbital-deflection effect. In principle, the width is independent on the target, and is consistently reproduced based on the previously proposed formulation. In contrast, the deflection effect shows a strong target dependence. In the case of one-nucleon removed fragments, the main part of the deflection effect can be understood by the Coulomb repulsion. The systematics of the momentum distributions, shown in the present studies, is important for evaluating the production cross sections of PLFs. Especially, the P_T distribution is crucial to deduce production cross sections from the production rates of PLFs, which are observed at the forward angle within the limited angular acceptance.

We report recent situation of anomaly in spin expectation value found in 9 C- 9 Li mirror pair, recent analysis of the nuclear spin in terms of orbital or intrinsic and proton or neutron, and a result from the study of the G -parity conservation law through β -ray angular correlation in terms of its nuclear orientation.

Based on more than 10 years of experience with HIMAC, we have proposed a new treatment facility for the further development of therapy with HIMAC. The new facility, as an extension of the existing one, has been designed and the related R&D work has been carried out. The following descriptions give a summary account of the design study and the related R&D work for this new treatment facility at HIMAC.

We have tested the timing properties of several thin plastic scintillators (10-500 mu m) designed for the Rare-RI Ring project at the R I beam factory. The experiments were performed at the heavy-ion synchrotron facility, HIMAC (Heavy Ion Medical Accelerator in Chiba), using a Xe beam with an energy of 200 MeV/nucleon. The scintillation light was read Out by fast-timing photomultipliers through standard fishtail-shaped light guides. The resultant timing resolutions reached a few tens of picoseconds, which satisfied our requirement for the project. We also measured charge-state distributions for Xe42+ and Fe20+ ions penetrating carbon foils of 10-500 mu g/cm(2) thickness. The results were compared with a theoretical model calculation for charge-state evolution. (c) 2008 Elsevier B.V. All rights reserved.

The magnetic moment of short lived β-emitter 24mAl (426 keV, Iπ = 1 + , T1/2 = 131 ms) has been measured by means of β-NMR technique, for the first time. From the β-NMR spectrum, the magnetic moment was determined as \(\left| {\upmu}\left( ^{\rm 24m}{\rm Al} \right) \right|=\left( {2.99\pm 0.09} \right){\upmu}_{\rm N}\). Combined with the known magnetic moment of the mirror partner 24mNa, the expectation value of is obtained to be (0.08 ± 0.12). These values are reproduced well by the shell model calculation.

For the effective utilization of the favorable properties of heavy-ion beams in cancer treatment, it is important to evaluate the range of incident ions and the deposited dose distribution in a patient's body. For this purpose, the utilization of positron emitters induced in therapeutic irradiation is, at present, the only feasible method for in situ and non-invasive monitoring of heavy-ion therapy. In this study, we performed irradiation experiments with three species of ions to a water target, and the annihilation gamma-ray distributions were obtained with a positron camera. We applied the maximum likelihood estimation (MLE) method for the detected distributions to derive the range of incident ions and the deposited dose distribution in the target. As a result, the ranges were determined with a difference between the MLE range R MLE and the experimental range R exp less than 1.1 mm. The good agreement between the estimated dose distribution with the MLE method and the measured one implies that a deposited dose distribution in a target could be estimated from a detected annihilation gamma-ray distribution.

In proton therapy, it is important to evaluate the field irradiated with protons and the deposited dose distribution in a patient's body. Positron emitters generated through fragmentation reactions of target nuclei can be used for this purpose. By detecting the annihilation gamma rays from the positron emitters, the annihilation gamma ray distribution can be obtained which has information about the quantities essential to proton therapy. In this study, we performed irradiation experiments with mono-energetic proton beams of 160 MeV and the spread-out Bragg peak beams to three kinds of targets. The annihilation events were detected with a positron camera for 500 s after the irradiation and the annihilation gamma ray distributions were obtained. In order to evaluate the range and the position of distal and proximal edges of the SOBP, the maximum likelihood estimation (MLE) method was applied to the detected distributions. The evaluated values with the MLE method were compared with those estimated from the measured dose distributions. As a result, the ranges were determined with the difference between the MLE range and the experimental range less than 1.0 mm for all targets. For the SOBP beams, the positions of distal edges were determined with the difference less thanmore » 1.0 mm. On the other hand, the difference amounted to 7.9 mm for proximal edges.« less

Reaction cross sections of Li-8 on stable targets were measured at intermediate energies. With the existing experimental data of interaction cross sections at 790 MeV/nucleon the nucleon density distribution of Li-8 was extracted by the use of the modified Glauber model. Meanwhile, the existing data of B-8 have been also reanalyzed. Structures of Li-8 and B-8 were compared through the density. On the basis of dilute surface densities, the discussion of Li-7(n,gamma) Li-8 and Be-7(p,gamma) B-8 capture reactions was performed within the framework of the direct capture reaction mechanism. The calculations agreed quite well with the experimental data as well as other analyses.

A compact cavity for acceleration has been developed with cobalt-based amorphous cores, which is a part of research and development (RD at both sides of the gap there are quarter-wave coaxial resonators. The total length of the cavity is as short as 1.5 m and the inner diameter of the vacuum chamber is 190 mm. Considering the requirements for easy operation and maintenance, a transistor RF amplifier was used instead of the commonly used tetrode in the final stage. Each resonator has a maximum impedance of 400 Ω at 2 MHz, and a 1:9 impedance transformer has been attached to use a solid state amplifier of 50 Ω output impedance. In the frequency range from 0.4 to 8 MHz, an acceleration voltage of more than 4 kV can be obtained with a total input RF power of 8 kW. In this paper the structure of the cavity, the obtained core impedance, and their performances under high-power test are presented.

Since 1994, the clinical trial for cancer therapy with HIMAC has successfully progressed, and more than 2100 cancer patients have been treated with a carbon beam. Based on the development of the accelerator and irradiation technologies for 10 years, we have designed a new carbon-therapy facility for widespread use in Japan, and key technologies for the new facility have been developed. We describe the conceptual design of the new facility and the status of development for the key technologies.

Based on 10 years experience of carbon therapy at HIMAC, new facility project is in progress at NIRS. In this paper, the design of the synchrotron and its transport system dedicated for carbon therapy based on the machine study at HIMAC and the results of the studies are presented. © 2001 Elsevier Science. All rights reserved

We developed a cobalt-based amorphous core as a new magnetic-alloy (MA) core for a loaded radio frequency (RF) cavity. Because of its low-quality-factor, high-permeability property, the core is suitable for constructing an untuned broadband accelerating cavity. While FINEMET FT-3M has been widely used as the core material, the permeability of our newly developed amorphous core is found to be approximately twice that of FINEMET FT-3M. This amorphous core is thus an excellent candidate for achieving a high-impedance cavity with low power consumption. Several measurements were taken in order to understand its feasibility and stability. The actual large-size cores were then manufactured for the first time for accelerator use.

Heavy ion cancer therapy using energetic 12C ions has been carried out successfully at the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. The method has advantages over traditional radiation therapy using an energetic photon beam in two respects: the dose concentration owing to the Bragg peak and high biological effects. The development of a cancer therapy using 11C ions is also currently underway at HIMAC, however, there remains the problem of beam attenuation due to nuclear fragmentation reactions in the body of the patient; this requires modification of the dose calculation for the therapy. To the best of our knowledge, no research on 11C-induced nuclear fragmentation reactions has yet been published. We propose a method of identifying the nuclear fragmentation reaction event induced by the carbon beams using a total-absorption-type target detector, that plays the role of a human phantom, and a system of plastic scintillation counters surrounding the phantom. We have carried out measurements for the carbon beams with the detector system. A portion of the beam energy is lost as escaping fragment particles from the phantom, leading to a decrease in beam intensity. We were able to successfully detect nuclear reaction events on an event-by-event basis

We performed an experimental study of charge identification of heavy ions from helium to carbon having energy of about 290 MeV/u using an emulsion chamber. Emulsion was desensitized by means of forced fading (refreshing) to expand a dynamic range of response to highly charged particles. For the track reconstruction and charge identification, the fully automated high speed emulsion read-out system, which was originally developed for identifying minimum ionizing particles, was used without any modification. Clear track by track charge identification up to Z=6 was demonstrated. The refreshing technique has proved to be a powerful technique to expand response of emulsion film to highly ionizing particles.

The momentum dependences of the nuclear spin polarization P and alignment A of 13B(I π = 3/2+, T 1/2 = 17.36 ms) produced in the 100A MeV 15N + Be collisions have been measured by detecting β-ray asymmetry. Because both the P and A were significantly smaller than the prediction from a simple kinematical model, some relaxation mechanisms must be take into account. Comparing the signs of the observed alignment of 12B, the sign of the quadrupole coupling constant eqQ of 13B in TiO2 was determined to be positive.

A magnetic alloy (MA)-loaded cavity has been installed in Heavy Ion Medical Accelerator in Chiba (HIMAC). A beam study with a new Direct Digital Synthesis (DDS) system has been performed. The DDS system can generate multi-harmonic RF that includes up to 3 different RF frequencies. The multi-harmonic RF is amplified by a solid state and final amplifiers. These harmonic frequencies are in the band width of the MA RF system. Beam acceleration was performed by the system, and the acceleration efficiency was improved by both dual and triple harmonic RF.

This article gives a new experimental estimate of the fraction of 11 C nuclear absorption in plastic scintillator, (C 9 H 10 ) n , according to nuclear reactions, and compares the results with an empirical formula based on a microscopic nuclear reaction model by Kox et al. [Phys. Rev. C 35 (1987) 1678]. The result establishes that the model is applicable to 11 C.

The emitted particles from a β -delayed particle decay beam must enhance biological effects in the region of interest and such a radioactive ion beam may be useful in cancer treatment. To test this therapeutic purpose of β -delayed particle decay beams, 9 C beams were produced in the secondary beam line at HIMAC for the first time. The thickness of production target and degrader to yield a 9 C beam with higher production rate and purity was optimized and the momentum distribution of the produced 9 C beam under the optimal condition was measured. For upcoming radiobiological experiments, a uniform irradiation field for the produced 9 C beam was made by means of wobbling magnets.

Secondary beam courses have been constructed at HIMAC. There are two beam courses, SB1 and SB2, which were designed as branches from the PH2 (a primary beam course) at the same point. The SB1 course is used mainly for medical applications with a positron emitter beam, where an irradiation system was installed for this purpose. The SB2 course is expected for general experiments. In this paper, the current status of the secondary beam courses in HIMAC is presented.

The magnetic moment of 33 Cl ( I π = 3 / 2 + , T 1 / 2 = 2.51 s ) has been re-measured precisely by β -NMR method. The obtained magnetic moment | μ | = 0.7549 ( 3 ) μ N is consistent with the old value 0.7523 ( 16 ) μ N , but is 5 times more accurate. The value is well reproduced by the shell model calculation, μ S M = 0.70 μ N . Combined with the magnetic moment of the mirror partner 33 S, the nuclear matrix elements 〈 l p 〉 , 〈 l n 〉 , 〈 S p 〉 , and 〈 S n 〉 were derived.

To investigate the production mechanism of projectile-like fragments (PLFs) at intermediate energies, the momentum distributions of PLFs produced in reactions at E / A = 95, 290, and 430MeV were measured at RIKEN and NIRS. A correlation and a systematics in the width of the transverse momentum distribution were derived from the results. The production cross sections derived from the observed momentum distributions show the target and the incident energy dependences.

The nuclear moments of 13B(Iπ = 3/2−, T1/2 = 17.36ms) have been re-measured precisely in order to establish the spin manipulation technique for the study of the alignment correlation term in mass system A = 13. From the β-NMR on 13B in Pt, the magnetic moment was determined as |μ(13B)| = 3.1778(5)μN. From the β-NQR on 13B in TiO2, the Q moment has been determined as |Q(13B)| = 36.6(8)mb. We have measured the alignment correlation term α_E for 13B β decay for the first time and obtained a preliminary result as α−(13B) = 0.15(12)%/MeV.

The momentum dependences of the nuclear spin polarization P and alignment A of 12 B ( I π = 1 + , T 1 / 2 = 20.20 ms) [ 13 B ( I π = 3 / 2 − , T 1 / 2 = 17.36 ms)] produced in 100 A MeV 13 C [ 15 N] + Be collisions have been measured by detecting the β -ray asymmetry. Because both the P and A were significantly smaller than the prediction from a simple kinematical model, some depolarization mechanisms must be taken into account related with the collision process itself. Comparing the signs of the observed alignment of 12 B and 13 B, the sign of the quadrupole moment Q ( 13 B) was determined to be positive.

Owing to the potentially therapeutic enhancement of delayed particles in treating malignant diseases by radioactive 9C-ion beam, LET spectra at different penetration depths for a 9C beam with 5% momentum spread, produced in the secondary beam line (SBL) at HIMAC, were measured with a multi-wire parallel-plate proportional counter. To compare these LET spectra with those of a therapeutic 12C beam under similar conditions, the 12C beam was replaced with an 11C beam, yielded in the SBL as well and having almost the same range as that of the 9C beam. The LET spectra of the 9C beam and its counterpart, i.e. the 11C beam, at various depths were compared, especially around the Bragg peak regions. The results show that nearby the Bragg peak lower LET components decreased in the LET spectra of the 9C beam while extra components between the LET peak caused by the primary beam and the lower components due to the fragments could be observed. These additional contributions in the LET spectra could be attributed to parts of the emitted particles from the radioactive 9C ions with suitable conditions regarding the LET counter. Integrating these LET spectra in different manners, depth-dose and dose-averaged LET distributions were obtained for the 9C and 11C beams, forming the basic data sets for further studies. In general, the depth-dose distributions of the 9C and 11C beams are comparative, i.e. almost the same peak-to-plateau ratio. The ratio for the 9C beam, however, has room to increase due to the geometric structure limitation of the present detector. The dose-averaged LETs along the beam penetration are always lower for the 9C beam than for the 11C beam except at the falloff region beyond the Bragg peak. Applying the present depth-dose and dose-averaged LET data sets as well as the essential radiobiological parameters obtained with 12C beams previously for HSG cells, an estimate concerning the HSG cell surviving effects along the penetration of the 9C and 11C beams shows that lower survival fractions for the 9C beam at the distal part of the Bragg peak, corresponding to the stopping region of the incoming 9C ions, can be expected when the same entrance dose is given. It is still hard to appreciate the potential of 9C beams in cancer therapy based on the present LET spectrum measurement, but it provides a substantial basis for upcoming radiobiological experiments.

A fast stochastic cooling is an inevitable function for the pre-cooling of RI beam. A new pick-up structure is designed and tested with heavy ion beam of 200 MeV/u. The measured results of characteristics of pick-up were described. In addition, a beam simulator was developed for the off line measurement of pick-up characteristic. Results of measurement of new type pick-up electrode were presented with the beam simulator.

A new type of beam chopper has been developed and installed at HIMAC (Heavy Ion Medical Accelerator in Chiba) in NIRS (National Institute of Radiological Sciences). The chopper has only 11.6 cm length and has been set between the ion sources and the RFQ. It is similar to a beam transformer, and modulates the beam kinetic energy by 10%. The beam is successfully chopped because the RFQ has a rather small energy acceptance. A chopped beam was injected into the synchrotron and a beam study has been performed. A very short bunch was formed and accelerated to the top energy. The behavior of the short bunch shows that a dipole oscillation was excited because of an unexpected frequency error of the RF system. It was caused by noise in the B-clock (Gauss Clock) circuit. The dipole oscillation caused by the frequency error was significantly reduced and the acceleration efficiency was improved by replacing the B-clock module.

A positron camera, consisting of a pair of Anger-type scintillation detectors, has been developed to verify ranges by using positron emitter beams. Each detector head is equipped with a NaI(Tl) crystal (diameter: 600 mm , thickness: 30 mm ) for high detection efficiency. To get a low counting rate for this application, the electric circuit was designed for flexibility in measurement and analysis by software. The energy and position were calibrated for high measurement accuracy. A spatial resolution of 8.6 mm in FWHM within a ±50 mm region (field of view) and a linear response of a 0.3 mm standard deviation within a ±200 mm region were obtained. The camera was designed so as to measure the ranges within an accuracy of 1 mm under a dose limitation (about 100 mGyE ) to reduce the safety margin for the irradiation field, and it met the required characteristics.

An irradiation method for spot scanning has been developed in order to provide accurate irradiation even for an irregular target shape. In spot scanning irradiation, the beam is turned off while the beam position is shifted to the next spot for precise dose management. Recently, the fast beam cut-off method, which can achieve a cut-off time of around 50 μs, was proposed and verified at the Heavy Ion Medical Accelerator in Chiba synchrotron. In order to utilize such a speciality of the technique for spot scanning, the characteristics of fast beam switching were investigated while turning on/off both the transverse and longitudinal RF fields many times during a single flattop. As a result, it was verified that this technique provides more than 50 spots during a single flattop in the synchrotron operation pattern with a cut-off time of 50 μs. With an increase in a switching number, the momentum spread and the size of the extracted beam increase within the allowable range for practical usage.

Two advanced RF-knockout (RF-KO) slow-extraction methods have been developed at HIMAC in order to reduce the spill ripple for accurate heavy-ion cancer therapy: the dual frequency modulation (FM) method and the separated function method. As a result of simulations and experiments, it was verified that the spill ripple could be considerably reduced using these advanced methods, compared with the ordinary RF-KO method. The dual FM method and the separated function method bring about a low spill ripple within standard deviations of around 25% and of 15% during beam extraction within around 2 s, respectively, which are in good agreement with the simulation results.

The RF-knockout (RF-KO) slow-extraction method with frequency modulation (FM) and amplitude modulation (AM) has brought high-accuracy irradiation to the treatment of a cancer tumor moving with respiration, because of a quick response to beam start/stop. However, a beam spill extracted from a synchrotron ring through RF-KO slow-extraction has a huge ripple with a frequency of around 1 kHz related to the FM. The spill ripple will disturb the lateral dose distribution in the beam scanning methods. Thus, the source of the spill ripple has been investigated through experiments and simulations. There are two tune regions for the extraction process through the RF-KO method: the extraction region and the diffusion region. The particles in the extraction region can be extracted due to amplitude growth through the transverse RF field, only when its frequency matches with the tune in the extraction region. For a large chromaticity, however, the particles in the extraction region can be extracted through the synchrotron oscillation, even when the frequency does not match with the tune in the extraction region. Thus, the spill structure during one period of the FM strongly depends on the horizontal chromaticity. They are repeated with the repetition frequency of the FM, which is the very source of the spill ripple in the RF-KO method.

The magnetic moment of the short-lived β emitter 35Ar ( I π =3/2 + , T 1/2 =1.77 s) has been remeasured by means of the combined technique of polarized nuclear beams and β-NMR. The obtained magnetic moment is 0.6322(2) μN. This value is consistent with the old data, but is one order of more magnitude precise. The value is well reproduced by the shell model calculation.

In cancer treatment with heavy ions, verification of the ion range in the patient's body is important. For this purpose, a positron emitter beam provides the possibility of range verification. To use the positron emitter beam, we have constructed a secondary beam course and its irradiation system. In this paper the constructed system is presented together with some results of beam experiments.

We have precisely measured reaction cross sections (sigma(R)) for Li-8 using Be-9, C-12, Al-27, and proton targets at intermediate energies by the transmission method. From the energy dependence of the sigma(R) including the high energy data, the density distribution of Li-8 was deduced through a modified Glauber model. It is shown that Li-8 has a shorter tail structure in the density as compared with that of B-8 and the matter radius of Li-8 is similar to those of the other nonhalo Li isotopes. The result is consistent with the previous experiments that there is a tendency for Li-8 to be a skin nucleus.

The positron camera system has been designed to measure heavy-ion ranges in patients' bodies. The pencil-like beam of positron emitters, such as /sup 11/C, is used to check the range directly and precisely by detecting pairs of annihilation gamma-rays emitted from the end point of the beam trajectory. The positron camera consists of a pair of Anger-type scintillation cameras. The efficiency and the spatial resolution are modeled and simulated by a Monte Carlo method and a numerical calculation so that the positron camera has a high position accuracy for a small amount of irradiation dose. The simulation shows that the optimum effective diameter of the camera crystal is 500 mm and its thickness is 30 mm. The crystal diameter is concluded to be 600 mm by taking the outermost photomultiplier mounting into account. The simulation moreover, indicates that the range can be measured within an accuracy of 1 mm under the limitation that the irradiation dose has to be less than a few percent of the therapeutic one.

Interaction cross sections have been measured for spin-aligned nuclear beams of deformed nucleus. The spin-aligned nuclear beams were created by selecting the momentum of fragments produced in the projectile fragmentation of intermediate energy heavy-ion beams. The directional correlation of nuclear reaction probability for heavy-ion beams of deformed nucleus has been directly observed for the first time.

Reaction cross sections ( σ R ) for 11Be and 8B on proton targets at 50 A ∼ 120 A MeV have been measured to distinguish between the proton- and neutron- density distributions at the nuclear surface. The σ R is connected with the nucleon density distributions by the Glauber theory. Since the nucleon-nucleon total cross sections in that energy region have a large isospin dependence, the σ R on proton targets should have a large difference between the proton and neutron in the halo structure. The experimental σ R on proton targets are in good agreement with the calculated ones assuming that the tail dominantly consists of a neutron for 11Be and a proton for 8B.

The magnetic dipole (μ) and electric quadrupole (Q) moments of short-lived nucleus 22F ( I π = 4 + , T 1 / 2 = 4.2 s ) have been measured for the first time by means of the β-NMR technique. A spin polarized 22F beam was produced through the charge exchange reaction of 22Ne and was implanted into single crysltals of NaF and MgF2 for μ and Q measurements, respectively. As a result, | μ ( F 22 ) | = ( 2.69443 ± 0.00039 ) μ N and | Q ( F 22 ) | = ( 3 ± 2 ) mb was obtained. These values are well reproduced by the shell model calculations.

The spin lattice-relaxation rates of short-lived unstable nuclei Al 25 and P 28 in Pt has been measured by means of the β-NMR technique, in order to study the electronic structure of dilute impurities in Pt. From the obtained spin-lattice relaxation rates, Knight shifts K c were estimated to be K c [ Al in Pt ] = ( 0.45 ± 0.09 ) × 10 − 3 and K c [ P in Pt ] = ( 4 − 4 + 2 ) × 10 − 3 using the Korringa relation. These values were evaluated by comparing to the first principle calculations.

An RF acceleration system, in which digital control with a direct digital synthesizer (DDS) is applied, has been developed for the Heavy Ion Medical Accelerator in Chiba (HIMAC) synchrotron. This digital system allows us to obtain stable operation of the acceleration system over a wide frequency range from 1.04 to 7.9 MHz. In this paper the designed digital RF control system and its performance are described.

High-intensity, high-quality beams originating from the electron-cooling method will be utilized for medical and other application at HIMAC. As a first step, an electron cooler with an adiabatic expansion factor of 10 has been designed and is under construction at HIMAC. So far, field measurements of the cooler have been completed. In this paper, the present status of the electron cooler under construction is described, and plans of medical and other application by using the electron-cooling method at HIMAC are presented.

Nuclear structure of proton-rich unstable nucleus 28P has been studied by measuring its g-factor for the first time. The g-factor of 28P (Iπ = 3+, T1/2 = 270.3 ms) was measured by means of β-NMR technique combined with the new polarization technique for charge exchange reaction product in the intermediate energy heavy ion collisions. The obtained g-factor of g = 0.1028(27) is very much quenched from the Schmidt value, but is well reproduced by the shell model (+0.102). In connection with the magnetic moment of the mirror partner and the β-ray transition probability, the orbital angular momenta and intrinsic spins of protons and neutrons have been determined as 〈lp〉 = 0.43(29), 〈ln〉 = 1.85(29), 〈Sp) = 0.28(4), and 〈Sn〉 = 0.44(4).

We proposed to apply the MLE method for determining the range of heavy ions and demonstrated the effectiveness of this method by experiments with 12 C beams. We performed irradiation experiments with stable 12 C ions of mono-energetic 290 MeV/u to a water, a polyethylene and a PMMA target. The theoretical ranges for 12 C ions of 290 MeV/u in these targets are 160.5, 157.9 and 139.8 mm, respectively. The annihilation events from positron emitters generated by 12 C ions were detected with a positron camera for 500 s just after the irradiation. To evaluate the range of 12 C ions, the MLE method was applied to the annihilation gamma ray distribution. The derived ranges for the three targets were 160.6, 158.9 and 140.4 mm, respectively. Therefore, we can conclude that the range of 12 C ions was determined within an accuracy of 1.0 mm for all targets.

Researchers explore the use of Bragg Ionization Peak in radiotherapy for tumors. Considerations for the production of a high quality radioactive beam include secondary beam production efficiency, primary beam survival, and multiple scattering. A Positron Emitting Beam Analyzing camera was developed and tested at BEVALAC using a neon-19 beam stopping point. Results indicate that in homogeneous brain tissues, CT measurements and radioactive beam measurements are between 1-2 mm; there can be substantial difference between CT measurements and radioactive beam estimates if the beam stopping point crosses the fossae; random coincidences due to detector activation also appear as diffused images in the image plane of the beam stopping point; and further enhancements are necessary to make reliable measurements in the human trunk and complex brain regions.

The angular distribution of proton-${}^{9}$C elastic scattering at 277--300 MeV/nucleon was measured with a newly designed recoil proton spectrometer. The angular distribution was analyzed using the relativistic impulse approximation. The root-mean-square matter radius of ${}^{9}$C was deduced to be $2.{43}_{\ensuremath{-}0.28}^{+0.55}$ fm with different two-parameter Fermi density distributions for protons and neutrons.

At the cooler-synchrotron TARN II, light- and heavy-ion beams are stored, electron-cooled and accelerated for the research of atomic physics and accelerator studies. In these experiments, the closed orbit distortion (COD) correction system plays an important role for improving the beam currents and lifetimes. In order to measure the position of a circulating faint beam in the ring, we developed beam diagnostic devices of high sensitivity and low noise. The beam positions can be measured with an accuracy of 0.3 mm at a circulating beam current of 1 μA. It is the purpose of the present paper to describe details concerning the beam position monitor (BPM) system, an investigation of the sensitivities of the BPM from the point of view the S N ratio, the experimental results of a COD correction and measurements of the accelerator parameters, such as the chromaticity and dispersion using this system.

A beam extraction method using a transverse rf electric field with amplitude and frequency modulation has been studied in order to develop an irradiation method which is synchronized with the breathing of a patient for high-quality charged particle therapy. The dependence of the extracted beam intensity on the voltage, the frequency band width and the center frequency of the transverse rf electric field has been investigated. The extracted beam intensity was slightly increased from that of the ordinary slow extraction method with a third order resonance. The response of the extracted beam intensity to the applied transverse rf electric field was as prompt as within 1 ms. The horizontal emittance of beams extracted by the present method was reduced by about 70% compared with that by the ordinary one due to utilizing a constant separatrix. Amplitude modulation can control the global beam spill structure. The frequency modulation reduced the effect of the current ripple of the main quadrupole magnets.