Energetical structure of muonic molecular ions ddµ and dtµ

The long-lived states lying below then=2 threshold in muonic molecular ions ddµ and dtµ are reviewed. We have considered all the known long-lived states both of normal and anomalous spatial parity, the bound states as well as resonant three-body states of shape and Feshbach types. It is shown that these states could be satisfactorily classified in terms of the Born-Oppenheimer adiabatic theory. We calculate some characteristic properties of the Feshbach resonances, thus obtaining that the life-time of the 3d states is greater than 10^–11 s, and the fusion rate from these states less than 10⁹ s^–1. The geometry of the 4f(J=0,v=0) state shows that it does not obey approximate ungerade symmetry. On the contrary, the low vibrational 3d states are approximately of gerade symmetry, as a result these states decay ejecting dµ atoms in the same proportion as tµ atoms.     

µ -symmetry and µ -conservation law for the extended mKdV equation

In this paper, we obtain µ -symmetry and µ -conservation law of the extended mKdV equation. The extended mKdV equation dose not admit a variational problem since it is of odd order. First we obtain µ -conservation law of the extended mKdV equation in potential form because it admits a variational problem, using it, we can obtain µ -conservation law of the extended mKdV equation.     

New RIKEN-RAL pulsed µCF facility and X-ray studies on DT-µCF

In November 1994, the construction of a new superconducting muon channel of the RIKEN-RAL muon facility at ISIS of Rutherford Appleton Laboratory was completed. Subsequently, important features, such as the highest instantaneous intensity with a single-pulse structure and a high purity have been confirmed. Along with the installation of advanced µCF experimental equipment, including a high-purity D-T mixture target system with an in situ³He removal capability and a 4 T confinement magnet, an advanced µCF experiment, e.g. a precise X-ray measurement on µ- sticking in dtµ-µCF will be realized. An account of the commissioning experiments, a plan for the earliest phase of the µCF experiment and possible future directions are reported.     

Inflationary cosmology with aR+λT µν R µν /R Lagrangian

We consider an alternative fourth-order gravity Lagrangian which is nonanalytic in the Ricci scalar, and apply it to a Robertson-Walker metric. We find vacuum solutions which undergo power-law inflation. Once matter is introduced the theory behaves very much like ordinary General Relativity, except that the radiation evolution t is not allowed since it corresponds toR=0. We comment on the possibility of wormhole solutions in such a theory.Also on leave from Fudan University, Shanghai, China     

Resonant ddµ-molecule formation in solid deuterium

The resonant ddµ-molecule formation process in solid deuterium is considered. It is shown that the rate of this process does not depend on temperature and is estimated to be _ddµ3µs^–1.     

Coulomb predissociation rates of He dµ molecular ions

The predissociation or particle emitting decay rates of muonic molecular ions³He dµ and⁴He dµ are estimated by means of the complex rotation method. We use a highly accurate variational three-bodyP-wave function based on random-tempered Slater-type exponential expansion. A resonance eigenvalue ofE=–48.420 89 eV and =0.348 × 10^–3 eV for the³He dµ ion and a resonance eigenvalue ofE=–58.225 303 eV and =0.118 × 10^–3 eV for the⁴He dµ ion have been obtained. These results are in a good agreement with the ones previously obtained by Kino and Kamimura by scattering calculation with the non-adiabatic coupled-rearrangement-channel method.     

A 300 µA Upgrade for the ISIS Accelerator

The Rutherford Appleton Laboratory (RAL) is home to the world's leading spallation neutron source ISIS [1]. The ISIS neutron producing target is driven by a 50 Hz, 800 MeV, 200 _A proton beam from a rapid cycling synchrotron, which is fed by a 70 MeV H_ drift tube linac (DTL) which in turn accepts beam from an H_ 665 keV Cockcroft-Walton preinjector. The ever increasing international demand for neutrons has motivated a bid to build a second target station at ISIS, for which £100 million funding has recently been approved by the U.K. government [2]. The second target station, operating at 10 Hz, will provide new scientific opportunities in soft condensed matter, biology and advanced materials.     

DNA interaction,anticancer, cytotoxicity and genotoxicity studies with potential pyrazine-bipyrazole dinuclear µ-oxo bridged Au(III) complexes

Molecular Diversity - Pyrazine-bipyrazole-based µ-oxo bridged dinuclear Au(III) complexes were synthesized and characterized by various spectrometric (1H-NMR, 13C (APT) NMR, FT-IR, Mass...     

Muon transfer in dµ + H2 collisions

The impact of excited state muon transfer in dμ + H₂ collisions has been investigated. The formation of metastable pdμ^* molecules and their subsequent decay into the pμ (1s) + d channel opens a transfer channel that is otherwise closed at the n=2 level. This mechanism enlarges the fraction of muons arriving to the ground state of the lighter isotope. The resulting ground state population P _1s ^pμ as function of deuterium concentration appears to be in qualitative agreement with recent measurements of the K _α X-ray yield in H₂/D₂ mixtures. This revised version was published online in August 2006 with corrections to the Cover Date.     

Design issues of 1.55 µm emitting GaInNAs quantum dots

We present a theoretical study of the optical properties of GaInNAs quantum dot (QD) structures, emitting at 1.55 µm wavelength. The theoretical model is based on a 10 × 10 k · p band-anti-crossing Hamiltonian, incorporating valence, conduction and nitrogen-induced bands. We have investigated the influence of the nitrogen to the conduction band mixing, and piezoelectric field on the ground state optical matrix element. For QDs grown on GaAs substrate with a reduced amount of indium and an increased amount of nitrogen in the QD the e _x polarized optical matrix element becomes on the average larger and less sensitive to the variation of both the QD shape and size than is the case of an InNAs QD. For the QD grown on InP substrate the dominant optical dipole matrix element is of the e _z light polarization. Our results identify the specific In and N content in the QDs required for optimal long-wavelength emission on both substrates.     

New effects in low energy scattering of pµ atoms

Strong solid state effects in low energy scattering of pμ atoms in solid hydrogen are reported and analyzed. Such effects have been observed in TRIUMF experiment E742 where muons are stopped in thin frozen (3 K) layers of hydrogen. Emission of low energy pμ atoms from the hydrogen layer into adjacent vacuum was much higher than expected, based on calculations which ignored the solid nature of hydrogen. Monte Carlo simulations, performed using the scattering cross-sections with solid state effects taken into account, show the important role of the coherent elastic Bragg scattering in the diffusion of pμ atoms. For pμ energies lower than the Bragg cut-off limit (∼2 meV) the total scattering cross-section falls by several orders of magnitude, the hydrogen target becomes transparent and the emission of cold pμ atoms takes place. This revised version was published online in August 2006 with corrections to the Cover Date.     

A new project for the investigation of unsolved problems of ddµ and pdµ catalysis in D2 and H/D mixtures

We propose to study a number of open problems in ddµ and pdµ fusion using the new high-pressure ionization chamber for charged particle identification in coincidence with the n-/e-counter array for the detection of neutrons and µ-decay electrons. Our first objective will be a precise measurement of the absolute rates of resonant and non-resonant ddµ formation in D₂ and HD-gases and their temperature dependence from 40 to 350 K. Both output channels of the dd-reaction:³He + n and t + p will be observed and their ratio sensitive to contributions of S and P-waves will be determined. Simultaneously, we shall investigate the pdµ-cycle and determine the absolute pd-fusion yields in different molecular H/D compositions, observing tritons from nuclear muon capture in³Heµ: pdµ ³Heµ + . We have developed a special system for the preparation of HD-gas with high concentration (96%) of HD and a purity (10^–6).     

Short-term frequency characteristics of 2 µm single frequency Solid-state lasers

The Short term frequency stability characteristics of 2 μm single frequency Solid-state lasers was investigated. The two laser systems of 2 μm single longitudinal mode oscillation Tm, Ho:YLF microchip laser and Ho:YAG NPRO laser were designed and constructed. The Short term frequency stability of these two laser were measured with the fiber delay self-beating heterodyne method. The 3dB width of the relative frequency fluctuation of Tm, Ho:YLF microchip laser and Ho:YAG NPRO laser were measured to be 895 and 736 Hz with 500 m fiber optical (2.5 μs delay). The proportional relation between the lasing fluctuation and the delay time were 358 and 263 Hz/μs, respectively. The vibration experiment was presented and it indicated that the NPRO Ho:YAG was more terrible to the influence of vibration, which is important in the practical application of wind measurement lidar.     

CO-laser side-band spectrometer: Sub-Doppler heterodyne frequency measurements around 5 µm

We report the realization of a tunable sub-Doppler heterodyne spectrometer with high absolute accuracy, employing side-band generation with a CO laser. The fixed-frequency CO-gas laser, working from 4.7 to 8.4µm, is made partially tunable by the use of microwave side-band generation in a CdTe Electro-Optical Modulator (EOM). This leads to tunable radiation of high spectral purity. We describe the design of the microwave EOM, adapted to the CO laser, its performance and its first application to highly accurate frequency measurements. The side-band radiation is used for sub-Doppler stabilization of the CO laser, while the carrier frequency is mixed with the frequencies of two CO₂ reference lasers. As a first result, we present measurements of OCS transitions in the 4.9µm (61 THz) region, reaching an absolute accuracy of 30 kHz (/ = 5×1O^–10). Further application of our spectrometer to calibration gases will establish a variety of InfraRed (IR) calibration standards with a new quality of accuracy. On visit from: Fachbereich Physik, Humboldt-Universität zu Berlin     

High-efficiency 1.9 µm Tm3+:LiLuF4 thin-disk laser

We present the first demonstration of a 792 nm diode-pumped Tm3+:LiLuF4 thin-disk laser operation around 1.9 μm. In multimode configuration, up to 21 W of output power and a maximal slope efficiency of 49% with an optical-to-optical efficiency of 40% was demonstrated. A tuning range from 1899 nm to 1927 nm could be achieved by inserting an etalon into the cavity.     

New approach to the old problem of muon sticking in µCF

A new approach is presented for evaluation of the muon sticking probability to helium in muon-catalyzed fusion reactions. Use of the sudden approximation is avoided. The probability _s of muon sticking to helium in the reaction dtµ µ⁴He+n, calculated with the new method, agrees with previous results. Moreover, the energy and angular distributions for the emitted muon, as well as the dependence of w_s on the energy radiated during the muon-catalyzed fusion event, have been evaluated.     

The CO fundamental-band laser as secondary frequency standard at 5 µm

We present a very high-resolution heterodyne spectrometer based on a CO laser which operates down to fundamental-band transitions of the molecule. This allows us to detect saturated absorption signals on these transitions at very low pressure (0.4 Pa) and laser intensity (< 1 mW/cm²), yielding a linewidth of about 250 kHz. With the CO fundamental-band laser stabilized to these saturation signals we have measured the transition frequencies of the fundamental bands of three isotopic species to an accuracy of typically 20 kHz (v/v 3 × 10^–10), referenced to the CO₂ frequency standard. Together with additional frequency measurements of the first hot bands, these provide the first heterodyne frequency data of sub-Doppler accuracy for transitions in low lying bands of CO. They now represent the most accurate secondary frequency standard in the spectral region around 5 µm (60 THz).     

Measuring the top quark mass in the eµ channel: A study

We describe a simple method to measure the top quark mass in the channel that may be useful in Run II of D? detector. The method is validated by applying it to the Run Ib eμ data.     

The Intensities of Methane in the 3-5 µm Region Revisited

The analysis of the linestrengths of the infrared spectrum of methane (12 and 13) in the 3-5 μm region has been revisited on the basis of new measurements from Fourier transform spectra recorded at Kitt Peak under various optical densities. A simultaneous fit of these new data with previously reported tunable difference-frequency laser data has been done. An effective transition moment model in tensorial form up to the third order of approximation within the Pentad scheme has been used. The standard deviations achieved are very close to the experimental precision: 3 and 1.5%, respectively, for the two sets of data for the (12)CH(4) molecule, representing a substantial improvement with respect to earlier studies. The integrated bandstrengths obtained in the present work differ from previously reported values by factors ranging from -5 to +6%. The correction for the nu(3) band, the strongest band of the Pentad system, is +2% with respect to the study of Hilico et al. [J. C. Hilico, J. P. Champion, S. Toumi, V. G. Tyuterev, and S. A. Tashkun, J. Mol. Spectrosc. 168, 455-476 (1994)]. Copyright 2000 Academic Press.     

Beam steering characteristics in high-power quantum-cascade lasers emitting at∼4.6µm

A beam steering effect of high-power quantum cascade(QC) lasers emitting at 4.6 μm was investigated. The continuous wave(CW) output power of an uncoated, 6-mm-long, 7.5-μm-wide buried-heterostructure QC laser at 25℃ was as high as 854.2 m W. The maximum beam steering angle was offset by ±14.2° from the facet normal(0°) in pulsed mode. The phenomenon was judged explicitly by combining the diffraction limit theory and Fourier transform of the spectra. It was also verified by finite element method software simulation and the calculation of two-dimensional(2 D)effective-index model. The observed steering is consistent with a theory for coherence between the two lowest order lateral modes. Therefore, we have established an intrinsic linkage between the spectral instabilities and the beam steering by using the Fourier transform of the spectra, and further presented an extremely valid method to judge the beam steering. The content of this method includes both three equidistant peak positions in the Fourier transform of the spectra and the beam quality located between once the diffraction limit(DL) and twice the DL.