Measurement and analysis of the ν2 band of D216O

The rotational structure of the ν₂ band of D₂¹⁶O between 700 and 1550 cm^?1 has been analyzed from spectra recorded with a Fourier transform spectrometer (nominal resolution: 0.1 cm^?1). By applying Watson's reduced Hamiltonian and a least squares method to the set of observed transitions, together with microwave data and the infrared data of Williamson, 22 rotational constants for the ground state and 17 for the upper state have been obtained which predict the positions of more than 700 observed lines with a standard deviation of 0.04 cm^?1.     

Infrared Spectroscopy of the ν1 Band of Sulfur Tetrafluoride, SF4

Infrared absorption spectra of the ν₁ axial S-F stretching vibrational bands of sulfur tetrafluoride, SF₄, have been recorded and analyzed. A diode-laser jet spectrometer was used to record high-resolution spectra of ³²SF₄, with 87 vibration-rotation lines of the ν₁ fundamental being assigned. Least-squares fitting of the data yielded a precise vibrational band origin, as well as rotational parameters for the upper state. In addition, lower-resolution spectra of a static sample of SF₄ held at room temperature were recorded using a Fourier transform (FTIR) spectrometer. The progressions of prominent features observed in the room-temperature FTIR spectra are attributed to summation bands arising from ν₁ transitions from excited vibrational levels of the low-frequency ν₄ manifold of both ³²SF₄ and ³⁴SF₄.     

Multiplicity dependence of intermediate-energy 12C, 18O and 20Ne induced reactions

Energy spectra of light particles emitted in the interaction of 84 MeV·A ¹⁸O and 48 MeV·A²⁰Ne ions with different targets have been measured with telescopes consisting of NaI, BGO and surface-barrier detector stacks. The inclusive data have been analysed within a moving-source parametrization. By using a large-area plastic-scintillator detector arrangement covering the target with a solid angle of about 2π, light-charged-particle multiplicity distributions have been measured and multiplicity-selected light-particle spectra have been obtained. It is shown that multiplicity selection allows a rough separation of peripheral and central processes and will be a suitable means for probing different theoretical models of nucleon emission.     

Analysis of prompt fission neutron spectrum and multiplicity for 237Np（n,f） in the frame of multi-modal Los Alamos model

The improved version of Los Alamos model with the multi-modal fission approach is used to analyse the prompt fission neutron spectrum and multiplicity for the neutron-induced fission of 237Np. The spectra of neutrons emitted from fragments for the three most dominant fission modes (standard Ⅰ, standard Ⅱ and superlong) are calculated separately and the total spectrum is synthesized. The multi-modal parameters contained in the spectrum model are determined on the basis of experimental data of fission fragment mass distributions. The calculated total prompt fission neutron spectrum and multiplicity are better agreement with the experimental data than those obtained from the conventional treatment of the Los Alamos model.     

Coincidence spectroscopy of pion-nucleaus interactions in 60Ni

The preevaporation phase of the interaction of 70 MeV pions with ⁶⁰Ni has been studied by measuring multinucleon removal spectra via prompt γ-ray spectra in coincidence with energetic charged particles. The data provide a direct estimate of the reaction cross section due to inelastic scattering and of the multiplicity of energetic protons emitter by the excited nucleus.     

Infrared diode laser spectroscopy of FCO: The ν1 and ν2 bands

The ν₁ (CO stretching) and ν₂ (CF stretching) bands of the FCO radical were observed with Doppler-limited resolution by an infrared diode laser spectrometer with Zeeman and source modulation. The FCO radical was generated by a 60-Hz discharge in one of the following three gas mixtures: O₂ + C₂F₄, CO + SF₆, and CO + C₂F₄, all diluted with He. The observed spectra were analyzed to determine the rotational constants, the centrifugal distortion constants, and the spin-rotation interaction constants. The band origins, 1861.6372(1) and 1026.1283(1) cm^?1 [with standard errors in parentheses], which were obtained, were found to agree well with matrix data, 1857 and 1023 cm^?1, respectively. The assignment of the observed spectra to the FCO radical was further supported by observing the ν₁ band of F¹³CO, which was obtained from ¹³CO and SF₆. The molecular structure and the force field of FCO are briefly discussed by using molecular constants obtained from the observed spectra.     

Quasielastic channel of single-stage nuclear fission induced by 1-GeV protons

Experimental indications that there exists single-stage fission of ²³⁸U and ²³²Th nuclei that is induced by a nearly transverse flux of intranuclear nucleons are obtained from an experiment that employs a two-arm time-of-flight spectrometer exposed to a beam of 1-GeV protons. A nearly transverse flux of mean multiplicity about 10 to 15 nucleons is initiated by a recoil nucleon of mean momentum about 240 MeV/c in the quasielastic scattering of an incident proton.     

Isotope effects in the infrared spectra of the polar and nonpolar isomers of N2O dimer

The rotationally resolved spectra of ¹⁵N¹⁵N¹⁶O dimer for the polar and nonpolar isomers are studied in the region of the N-N stretching fundamental of the monomer (∼2150 cm⁻¹) using a rapid-scan tunable diode laser spectrometer to probe a pulsed supersonic jet expansion. These spectra are very similar to the corresponding spectra of the normal species, (¹⁴N¹⁴N¹⁶O)₂. Structural parameters and vibrational shifts obtained here are compared with those of the normal species and ab initio values. These results confirm that the nonpolar isomer has a centrosymmetric slipped-antiparallel structure while the polar isomer consists of two slipped and (approximately) parallel monomer units.     

The breakup of 16O into He: An event-by-event study of nucleus-nucleus collisions at 75, 175 and 2000 MeV/A

We present an event-by-event study of the breakup of the ¹⁶O in ¹⁶O + emulsion nucleus interactions at 75, 175 and 2000 MeV/A. The events are categorized according to their multiplicity of projectile He nuclei. The multiplicity depends on the degree of target destruction. Although the fragmentation model describes the gross features of inclusive He spectra, an event-by-event study reveals deviations from the model. The momenta of the He nuclei, emitted from the projectile, depend on helium multiplicity and the breakup properties of the target nucleus. The probability that the ¹⁶O projectile breaks up into multiple He fragments is larger at 75 MeV/A than at 2000 MeV/A. At 75 MeV/A the mean velocity of projectile He is on the average 0.06c below the projectile velocity. This recoil velocity depends on the target nucleus destruction also for the most peripheral collisions.     

Simulation of the xenon gamma spectrometer for analyzing radioactive materials

The results of the calculation of the detection efficiency of gamma-rays for the xenon gamma spectrometer (XGS) obtained using the GEANT4 Monte Carlo simulation are presented. The gamma spectra of the set of basic standard gamma-sources (OSGI) are analyzed for a real detector, and the calculated and actual detection efficiencies are compared. The XGS spectra are analyzed to determine the minimum concentration of the ¹⁵²Eu radio nuclide in the ¹³⁷Cs and ⁶⁰Co mixture. It is shown that the xenon gamma spectrometer is capable of detecting the isotope at concentrations above 40% in the mixture.     

The 63Cu(p,p'γ) reaction and the structure of 63Cu

Levels in ⁶³Cu were studied by means of the ⁶³Cu(p, p'γ) reaction at incident proton energies E_p = 4.2, 5.0 and 6.0 MeV. Singles γ-ray spectra were obtained with a Ge(Li)-NaI(Tl) spectrometer. A total of 57 γ-transitions up to 2889.4 keV have been found and a detailed level scheme for the de-excitation of 22 levels in ⁶³Cu is proposed.     

Classical-equations-of-motion calculations of multiplicities for high-energy collisions of 20Ne+20Ne

Nucleon multiplicity distributions have been obtained as a function of impact parameter b for ²⁰Ne + ²⁰Ne at a laboratory energy of 800 MeV/nucleon with classical-equations-of-motion calculations. The average multiplicity decreases-quite rapidly with b, but there is a quite wide spread of multiplicities for a given b. This indicates, at least for equal-mass, light nuclei, that the multiplicity can only determine the impact parameter with rather poor resolution.     

Determination of the Isotope Shift of the 00Band of the First Singlet–Singlet Electronic Transition of Cl- and Br-Benzene in a Supersonic Beam

By using resonance-enhanced two-photon ionization in a supersonic beam, photoionization spectra of the 0⁰₀band of the first singlet–singlet electronic transition of³⁵Cl-,³⁷Cl-,⁷⁹Br-, and⁸¹Br-C₆H₅have been obtained at a rotational temperature of 1 K. The ions have been analyzed according to their masses in a time-of-flight mass spectrometer. From the spectra of³⁵Cl- and³⁷Cl-C₆H₅obtained simultaneously, an isotope shift of 0.14 ± 0.02 cm⁻¹has been determined. Similarly, from the spectra of⁷⁹Br- and⁸¹Br-C₆H₅the isotope shift resulted to be smaller than 0.02 cm⁻¹. The spectra obtained have been interpreted by considering the geometrical structure and symmetry of each molecule, and values for the rotational constants and geometrical parameters in the upper and lower states have been obtained in agreement with the experimental results.     

In-beam study of 136Ce and 138Nd isotones with N = 78

Excited states in ¹³⁶Ce and ¹³⁸Nd have been investigated by means of in-beam spectroscopy with the (p, 4nγ) reaction. Excitation functions and angular distributions of γ-rays were measured with a Ge(Li) detector, and conversion electron spectra were taken with a magnetic spectrometer. Time-dependent spectra of γ-rays revealed delayed components with half-lives of 2.2μsec and 0.41μsec in ¹³⁶Ce and ¹³⁸Nd, respectively. Most of the excited states are classified as belonging to the quasi-ground-state rotational band and the quasi-gamma band. Negative parity 5^? and 7^? states were also observed.     

On spectral temperatures of negative pions produced in d 12C, 4He12C, and 12C12C collisions at 4.2 A GeV/c

The experimental transverse momentum distributions of negative pions produced in d ¹²C, ⁴He¹²C, and ¹²C¹²C collisions at 4.2 A GeV/c were analyzed in the framework of Hagedorn Thermodynamic Model. The spectral temperatures of π ^? mesons as well as their relative contributions to the total multiplicity of π ^? mesons were extracted from fitting the p _t spectra by two-temperature Hagedorn function. The results were compared systematically with the earlier results obtained from analysis of non-invariant center-of-mass energy spectra of negative pions produced in the analyzed collisions.     

The diode laser spectrum of the ν2 band of 14ND3 and 15ND3

The spectra of the ν₂ bands of ¹⁴ND₃ and ¹⁵ND₃ were measured under Doppler-limited resolution with a diode laser spectrometer in order to resolve the K structure of the sR(J, K) and aR(J, K) multiplets. By a simultaneous least-squares analysis of these data, the Fourier spectra of the ν₂ band measured by Jones [J. Mol. Spectrosc.74, 409 (1979)], and the ground-state microwave transitions, sets of improved ν₂-band parameters were obtained, including the sextic centrifugal distortion coefficients.     

Broadening of the R(0) and P(2) lines in the CO fundamental by helium atoms from 300 K down to 12 K: Measurements and comparison with close-coupling calculations

We present measurements of He-broadening parameters for the R(0) and P(2) lines in the fundamental band of ¹³CO at different temperatures between 12 K and room temperature. The broadening parameters are determined, taking into account confinement narrowing, by simultaneous least-squares fitting of spectra recorded using a frequency stabilized diode laser spectrometer. The pressure broadening cross sections are deduced and compared to close-coupling calculations and earlier results obtained for rotational transitions of ¹²CO.     

EPR studies of Gd3+-doped Ce2(SO4)3.8H2O and La2(SO4)3.9H2O single crystals

EPR spectra of Gd³⁺-doped Ce₂(SO₄)₃.8H₂O and La₂(SO₄)₃.9H₂O single crystals have been measured with an X-band spectrometer at room and low temperatures. The absolute signs of spin Hamiltonian parameters have been determined for the La₂(SO₄)₃.9H₂O host from intensities of lines at liquid helium temperature; for the Ce₂(SO₄).8H₂O host the lines broaden considerably below 60 K, not permitting the determination of absolute signs of spin Hamiltonian parameters. The data are analysed using a rigourous least-squares procedure, fitting simultaneously all lines obtained for several orientations of the external magnetic field. The zero-field splittings have been computed for both the hosts. The characteristics of EPR spectra of Gd³⁺ in these hosts are compared with those obtained in other rare-earth trisulphate octahydrate hosts.     

Multiplicity structure of proton and kaon diffractive dissociation in 10 and 16 GeV/c K-p interactions

A new method to calculate diffractive mass spectra has been developed. It is applied to K^-p interactions at 10 and 16 GeV/c. Cross sections and mass spectra are given for the difractive dissociation processes p→(N+iπ) and K^-p→(K+iπ) for i = 1 to 5 and also summed over all multiplicities. In addition to the diffractive peak at low mass coming from low multiplicities, a long tail extending to high masses and high multiplicities has been found. The multiplicity structure of diffraction dissociation can be understood in the context of the two-step dynamical picture of Pokorsky and Van Hove.     

Multiplicity dependence of particle spectra: A peripheral phase-space description with application to 19 GeV/c pp reactions

As an attempt to describe the overall features of spectra of particles produced in hadronic interactions at high energy, we propose a peripheral phase-space model which incorporates restricted transverse momenta to the outgoing particles as well as a leading particle effect. Simulating proton-proton interactions at 19 GeV/c beam momentum, we examine the effect of modifying Monte-Carlo generated events by a matrix element containing a factor (?bp_⊥²) for each outgoing particle and an exponential damping exp (at) in the momentum transfer to each of the final baryons. With a fixed set of cut-off constants, we give a survey of spectral shapes obtained for particles of different types, pions, kaons, nucleons and hyperons. In particular, the generated longitudinal spectra are shown to have a distinct dependence on multiplicity. A comparison is carried out with existing data on 19 GeV/c pp interactions obtained by the Scandinavian Bubble Chamber Collaboration.