No abstract available

No abstract available

[en] Using the one-dimensional field gradient distribution along the symmetry axis of quadrupole magnets, the conventional three-dimensional field distribution function has been successfully describing the magnetic field within the bore radius R. In the present study, the conventional formalism was found to cause singularities beyond the radius. A new distribution function has been derived which is free from the singularities. The region of the reliable magnetic field distribution function has been extended from r< R of the conventional formalism to xy< R²/2 of the new one. By positive use of the extended region, the electric power consumption of quadrupole magnets can be reduced more than one order of magnitude.

[en] A quadrupole magnet is proposed whose gap is not constant, but depends on the position along the symmetry axis. We were able to formulate a magnetic field distribution function that can reproduce the three-dimensional field distribution of any slanted-gap quadrupole magnet with seven parameters. The relative gain in the focusing power by the slanted-gap quadrupole magnet was estimated to be 0.3-0.7 times the gap difference divided by the mean gap, depending on the field strength. The slanted-gap quadrupole magnet will be useful when we need as high a field gradient and as large a gap as possible under tight spatial and electrical power restrictions

[en] A new method of describing the magnetic fringing field is proposed. While the traditional method gives the two-dimensional magnetic field distribution by terminating the summation of the Maclaurin expansions at a finite derivative order, we summed the expansions up to infinity using the complex variable method. The exact summation shows an occurrence of singularities to which no attention has been paid. Because the traditional empirical function causes many unnecessary singularities where there should not be in the two-dimensional space, we derived a new empirical function whose singularities are located where they should be. The new function can reproduce the two-dimensional field distribution seamlessly and very precisely in the full region where we need the field information

[en] The nuclear levels of Na-20 are studied experimentally using the (He-3, t) and (p, n) reactions on Ne-20. The spin parities and excitation energies are determined for the states near and above the p + Ne-19 threshold. The stellar reaction rate of the Ne-19(p, gamma) process is evaluated based on the data. The calculation shows a more than two orders of magnitude larger rate than the previous theoretical predictions. The finding of s-wave resonance just above the capture threshold may change the onset temperature of breakout from the CNO cycle and explains the strong enhancement of Ne and heavier elements in observations of nova V1370 Aql 1982. 16 refs

[en] KOBRA (KOrea Broad acceptance Recoil spectrometer and Apparatus) is a mass separator that is being designed for experiments to study nuclear astrophysics, nuclear spectroscopy, symmetry energy and spin polarization with low energy stable/RI beams up to ∼20 MeV/nucleon at RAON. KOBRA is divided into two-stage configurations consisting of in-flight separator and recoil spectrometer. The first stage as an in-flight separator consists of double achromatic separator and short length Wien filter. The second stage consists of rotatable QQD-type spectrometer with long length Wien filter. KOBRA has been designed to enable reaction experiments using the RI beams which are produced by not only transfer reactions but also quasi-projectile fragmentation. (author)

[en] Alpha-cluster states in ⁴⁰Ca, ⁴⁴Ti and ⁹⁴Mo have been investigated by the ³⁶Ar(⁶Li,d)⁴⁰Ca at E = 50 MeV, the ⁴⁰Ca(⁶Li,d)⁴⁴Ti reaction at E 50 and 37 MeV and the ⁹⁰Zr(⁶Li,d)⁹⁴Mo reaction at E = 37 MeV. Parity-doublet bands in ⁴⁰Ca and ⁴⁴Ti have been successfully established, while the trial to obtain the angular distributions of the ⁹⁰Zr(⁶Li,d)⁹⁴Mo reaction was unsuccessful. This report reviews our experimental search for the α-clustering states in A ≥ 40 nuclei. For the ⁴⁴Ti nucleus, the angular distributions of positive-parity members of the ground-state band (the K^π = 0⁺ band) in ⁴⁴Ti were well reproduced by the finite-range distorted-wave Born approximation calculations up to the transferred angular momentum of L = 8. The members of the negative-parity band (the K^π = 0^- band) with the principal quantum number N = 13 were fragmented into several levels. The summed spectroscopic factors for each spin give reasonable values as the α-clustering structure. The strongly excited state at E_x = 10.86 MeV by the 37 MeV experiment was found to be a candidate for the head of the higher-nodal K^π = 0⁺ band with N 14. For the ⁴⁰Ca nucleus, the J^π = 8⁺ state was found at 10.34 MeV, and the 6.93 MeV level was confirmed as a J^π 6⁺ state. These states are considered as the members of the K^π = 0⁺ band starting from the 0⁺ state at E_x = 3.35 MeV. The members of the negative-parity counterpart in the parity doublet bands were observed, in some fragments, from the 1^- state at 8.15 MeV to the 7^- state at 13.83 MeV of excitation energy. Members of the K^π = 2⁺ band with excited ³⁶Ar core (2⁺) and α-cluster, were also observed. The 0⁺, 2⁺, 4⁺ and 6⁺ members of a higher-nodal K^π = 0⁺ band with N = 14 were observed. They are also fragmented into strongly populated states in an excitation energy region from the 0⁺ state at 11 MeV to the 6⁺ state at 15 MeV. The large spectroscopic factors suggest a much stronger α-clustering character. The existence of a negative-parity band and the completion of the parity-doublet bands in ⁴⁰Ca and ⁴⁴Ti give considerable support to α-cluster models for nuclei heavier than A = 40. (author)

[en] The KOBRA (KOrea Broad acceptance Recoil spectrometer and Apparatus) is a multi-purpose recoil spectrometer for low-energy nuclear experiments at the RAON accelerator complex. It is divided into two stages based on the operational function: the first stage (F0-F3) is an in-flight separator or beam transport line, and the second stage (F3-F5) is a large acceptance spectrometer. For spectrometers using radioactive ion (RI) beams, high performance, such as high resolution and large acceptance, are especially required due to the limit of quality of RI beams. In this respect, a dispersion-matching technique and a movable magnet system were employed for high resolution and large acceptance, respectively. Reaction spectra at the focal plane for the dispersion matching mode were obtained and analyzed using a Monte Carlo simulation code. In addition, the geometrical angular acceptances with respect to the distance between the reaction target and the first Q-pole doublet of the second stage were calculated, and the expected maximum solid angle of the spectrometer was estimated.

[en] The HKS (Jlab E01-011) experiment on spectroscopy of Lambda-hypernuclei using (e,e'K+) reaction was successfully carried out in 2005. This paper gives a brief description of the experiment and its technique and shows some of the preliminary spectra that are still under analysis.