Development of modulating permanent magnet sextupole lens for focusing of pulsed cold neutrons

Modulating permanent magnet sextupole lens (PMSx) for focusing pulsed cold neutrons is under development. The synchronized modulation of its field gradient suppresses the chromatic aberration which arises from the Time Of Flight method. The strength of the magnetic field, the torque, and the rise of temperature during its operation are studied on a fabricated prototype. Experiments on focusing pulsed very cold neutrons (VCN) at ILL (Institute of Laue Langevin, France) were carried out and VCN with around λ=40 Å were focused by the PMSx at a focal length of about 0.5 m. The experimental results are presented in conjunction with the principle of the neutron focusing and the modulating method of the focal strength of permanent magnet lens with the double ring structure.     

Enhanced electron-capture decay rate of 7Be encapsulated in C60 cages

The decay rate of 7Be electron capture was measured in C60 and Be metal with a reference method. The half-life of 7Be endohedral C60 ((7)Be@C(60)) and 7Be in Be metal (Be metal (7Be)) is found to be 52.68+/-0.05 and 53.12+/-0.05 days, respectively. This amounts to a 0.83% difference in electron-capture decay half-life between (7)Be@C(60) and Be metal (7Be). Our result is a reflection of the different electron wave functions for (7)Be@C(60) inside C60 compared to the situation when 7Be is in a Be metal.     

Achievement of ultralow emittance beam in the accelerator test facility damping ring

For high luminosity in electron-positron linear colliders, it is essential to generate low vertical emittance beams. We report on the smallest vertical emittance achieved in single-bunch-mode operation of the Accelerator Test Facility, which satisfies the requirement of the x-band linear collider. The emittances were measured with a laser-wire beam-profile monitor installed in the damping ring. The bunch length and the momentum spread of the beam were also recorded under the same conditions. The smallest vertical rms emittance measured at low intensity is 4 pm at a beam energy of 1.3 GeV, which corresponds to the normalized emittance of 1.0x1.0(-8) m. It increases by a factor of 1.5 for a bunch intensity of 10(10) electrons. The measured data agreed to the calculation of intrabeam scattering within much better than a factor of 2.     

Absorption spectra and Zeeman effects of Tm3+ in CaF2

The absorption spectra of Tm³⁺ in CaF₂ were analyzed by the concentration series method at 4·2^°K. Systems of lines, belonging to Tm³⁺ion centers of different structure, are isolated from the general spectra. Some of structures of Tm³⁺ ion centers were made clear by studying optical Zeeman effects and a change of absorption lines during thermal treatment. The tetragonal crystal field parameters and g-value of the upper state are also discussed.     

Observation of rho/omega meson modification in nuclear matter

We measured the invariant mass spectra of electron-positron pairs in the target rapidity region of 12-GeV p+A reactions. We have observed a significant difference in the mass spectra below the omega meson between p+C and p+Cu interactions. This difference indicates that the spectral shape of mesons is modified at normal nuclear-matter density.     

Adhesion of ethylene-tetrafluoroethylene copolymer with silicate glasses

The adhesive strength of ethylene-tetrafluoroethylene copolymer (ETFE) was measured on silicate glass substrates. A value of over 300 kg/cm² obtained with a commercial soda-lime-silica glass and this initial adhesiveness was attributed to the marked wettability of molten ETFE and its chemical structure. Since the decrease in the adhesive strength was small after immersion in water for a dealkalized soda-lime-silica glass, Pyrex, and a soda-lime-silica glass coated witn In₂O₃, it was inferred that the sodium ions in the soda-lime-silica glass played a fundamental role in lowering the adhesive strength in the presence of water. Pretreatment with N-(β-aminoethyl)-γ-aminopropyl-trimethoxy silane markedly improved the water durability of the adhesive strength.     

Observation of incoherent diffraction radiation from a single-edge target in the visible-light region

An experiment to investigate the diffraction radiation from a single edge target has been performed at the accelerator test facility of KEK with the aim of developing noninvasive beam diagnostics. The yield and the angular distribution of diffraction radiation as a function of the impact parameter was measured in the visible light region. The distributions were qualitatively consistent with the theoretical expectation. This work exhibits the first observation of the incoherent diffraction radiation in the visible light region.     

Spin alignment of43Sc produced in the fragmentation of 500 MeV/u46Ti

In the fragmentation of 500 MeV/u⁴⁶Ti the spin alignment of^43mSc (I=19/2^?, T_1/2=473 ns) fragments was observed by the Time Dependent Perturbed Angular Distribution (TDPAD) method. The measurement was performed for different cuts in the longitudinal momentum distribution. A positive spin alignment of about 35% was observed in the center and a negative alignment of about 15% in the wing of the distribution. For the different cuts the relative production of the 19/2^? state was measured. In the wing of the distribution the isomeric ratio N(19/2^?)/total⁴³Sc is about 15 times larger than in the center. The results of this pilot experiment are discussed in the frame of a shell-model.     

Synthesis of 7-methoxy-2-methyl-3,5,8-isoquinolinetrione

Synthesis of 7-methoxy-2-methyl-3,5,8-isoquinolinetrione from either 7- or 8-isoquinolinol is described. 3,5,8-Isoquinolinetrione is a novel heteroeyelic quinune which constitutes the aromatic carbon skeleton of mimosamycin.