First Precision Spectroscopy of Pionic Atoms at RI Beam Factory

We conducted an inclusive missing-mass spectroscopy of ¹²²Sn (d, ³He) reaction near the π¯ emission threshold at an incident energy of T _d = 250 MeV/nucleon. The experiment sets its goals to the research and development of the high precision spectroscopy of pionic atoms at the RI beam factory (RIBF) of RIKEN, which precedes a new project, pionic atom factory project (piAF), to observe pionic atoms systematically. Here, we report the preliminary results of the pilot experiment.     

Measurements of the strong-interaction widths of the kaonic (3)He and (4)He 2p levels

The kaonic (3)He and (4)He X-rays emitted in the [Formula: see text] transitions were measured in the SIDDHARTA experiment. The widths of the kaonic (3)He and (4)He 2p states were determined to be [Formula: see text], and [Formula: see text], respectively. Both results are consistent with the theoretical predictions. The width of kaonic (4)He is much smaller than the value of [Formula: see text] determined by the experiments performed in the 70's and 80's, while the width of kaonic (3)He was determined for the first time.     

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.     

Experimental investigation of ≈130 keV kinetic energy antiprotons annihilation on nuclei

The recent observation of single spins flips with a single proton in a Penning trap opens the way to measure the proton magnetic moment with high precision. Based on this success, which has been achieved with our apparatus at the University of Mainz, we demonstrated recently the first application of the so called double Penning-trap method with a single proton. This is a major step towards a measurement of the proton magnetic moment with ppb precision. To apply this method to a single trapped antiproton our collaboration is currently setting up a companion experiment at the antiproton decelerator of CERN. This effort is recognized as the Baryon Antibaryon Symmetry Experiment (BASE). A comparison of both magnetic moment values will provide a stringent test of CPT invariance with baryons.     

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.     

Conformationally selective transannular cyclizations of humulene 9,10-epoxide. Synthesis of the two skeletally different cyclohumulanoids: dl-bicyclohumulenone and dl-africanol

Two cyclohumulanoids, dl-bicyclohumulenone ($\text{4}$) and dl-africanol ($\text{7}$ were synthesized through newly developed conformationally selective transannular cyclization of humulene 9,10-epoxide ($\text{2}$). The epoxide $\text{2}$ was converted to a bicyclohumulenediol diacetate $\text{3a}$ in 70% yield by treatment with BF₃·OEt₂-Ac₂O, while treatment of $\text{2}$ with trimethylsilyl trifluoromethansulfonate gave an africen-10-ol ($\text{5}$a and $\text{5}$b) in 80% yield. The two intermediates $\text{3a}$ and $\text{5a}$ furnished the natural products $\text{4}$ and $\text{7}$ in 30 and 8 % yield from $\text{2}$ respectively.     

Towards antihydrogen trapping and spectroscopy at ALPHA

Spectroscopy of antihydrogen has the potential to yield high-precision tests of the CPT theorem and shed light on the matter-antimatter imbalance in the Universe. The ALPHA antihydrogen trap at CERN??s Antiproton Decelerator aims to prepare a sample of antihydrogen atoms confined in an octupole-based Ioffe trap and to measure the frequency of several atomic transitions. We describe our techniques to directly measure the antiproton temperature and a new technique to cool them to below 10 K. We also show how our unique position-sensitive annihilation detector provides us with a highly sensitive method of identifying antiproton annihilations and effectively rejecting the cosmic-ray background.     

Resolution enhancement of pHe+ atomic line profiles measured with a pulsed dye laser and a Fizeau wavelength meter

A Fizeau wavelength meter was used to compensate for fluctuations in the longitudinal mode structure and wavelength of a pulsed dye laser. The average laser linewidth was effectively narrowed by selection of laser pulses with a single longitudinal mode. These techniques were recently employed to measure some atomic transition wavelengths in pHe+ to fractional precisions greater than 1 part in 10(7). The wavelengths were absolutely calibrated against iodine or tellurium lines by absorption spectroscopy or against neon or argon lines by optogalvanic spectroscopy.