Results from the NOMAD experiment

The NOMAD experiment has sought ν_μ ? ν_τ oscillations by looking for the emergence of τ^? in events from the CERN SPS neutrino beam. With some improvements in the techniques of analysis in relation to the results published previously and with the inclusion of data from the 1998 run, no evidence for the oscillations has been found, which results in an updated limit on the oscillation probability [P(ν_μ → ν_τ) < 0.5 × 10^?3 at a 90% C.L.]. The corresponding limit on the oscillation mixing angle is given by sin²2θ_μτ < 1.0 × 10^?3 for large Δm ². By using a 1% contamination of ν_e in the neutrino beam, we can also rule out ν _e ? ν_τ oscillations and constrain the probability of the relevant transition as P(ν _e → ν_τ) < 3 × 10^?2 at a 90% C.L. (sin²2θ _eτ < 6 × 10^?2 at large Δm ²).     

Present status of the opera experiment for the direct observation of neutrino oscillations in the νμ → ν τ channel

The OPERA experiment (Oscillation Project with an Emulsion-Tracking Apparatus) for the direct observation of neutrino oscillations in the ν_μ → ν _τ channel has been underway at the underground laboratory in Gran Sasso since 2007. In the course of data collection, more than 3000 ν_μ interactions have been registered in emulsion detectors. Twenty charmed neutrino interaction candidates have been found. Multidimensional criteria have been developed in order to select ν _τ interactions against νμ interactions accompanied by charmed hadron production. The first results from automated PAVIKOM emulsion scanning have been obtained. We discuss the measurements of the muon charge ratio of μ⁺ to μ^?.     

The ντ-mass and the τ-decay modes

The behaviour of the different decay modes of the charged heavy lepton τ versus the neutrino ν_τ-mass is analyzed in detail. The τ→ν_τ A ₁ and τ→ν_τ K ^* decay rates have been evaluated using finite energy sum rules. The τ→ν_τ+ “Hadron Continuum” decay rate has been estimated within the framework of Quantum Chromodynamics (QCD). We find that the branching ratios of the semi-leptonic processes: τ→ν_τρ, τ→ν_τπ and τ→ν_τ+ “Hadron Continuum” are very sensitive to the value of the ν_τ-mass. Thus a more precise measurement of these branching ratios could provide an improved upper bound for the neutrino ν_τ-mass.     

Vibrational relaxation time measurements in CH4 and CH4-rare gas mixtures

With a spectrophone vibrational relaxation times in CH₄ and in mixtures of CH₄ with rare gases were measured. Both the amplitude and the phase method were used. The two infrared active modes of CH₄ (ν₄ and ν₃) were investigated separately. The relaxation times, at one atmosphere, after exciting the lowest mode ν₄, were found to be: τ(CH₄-CH₄) = 1.65 μs; τ(CH₄-He) = 1.97 μs; τ(CH₄-Ne) = 8.6 μs; τ(CH₄-Ar) = 12 μs and τ(CH₄-Kr) ≈ 60 μs. From these values one may in that vibrational-rotational (V-R) energy transfer is the dominant relaxation mechanics. By exciting the higher mode the first step in the deactivation of ν₃ was found to be a V-V transfer to the lowest modes ν₄, ν₂.     

Measurements of tau decay modes and a precise determination of the mass

The cross sections for e⁺e^? → e⁺(μ⁺ + non showering track + any photons have been measured for cm energies between 3.1 GeV and 5.2 GeV. We observe τ-pair production below the thresholdfor charm production and determine the τ mass to be 1.807 ± 0.020 GeV from a fit to the energy dependence of the cross section. The ration of the leptonic branching ratios B_μ/B_e = 0.92 ± 0.32 is consistent with eμ-universality. The following branching ratios are determined for a V-A coupling: $\text{B(τ → ν}{}_{\mathrm{\tau }}\text{e}\text{ν}\text{) = B(τ → ν}{}_{\mathrm{\tau }}\text{μ}\text{ν}\text{) = 0.182 + 0.028}$. B(τ → ν_τ + charged hadron + any photons) = 0.29 ± 0.11, B(τ → ν_τ + three or more charged hadrons + any photons) = 0.35 ± 0.11.     

The OPERA experiment

The OPERA (oscillation project with emulsion-tracking apparatus) experiment aims to observe an unambiguous ν_π?ν_τ oscillation in the parameter region allowed by previous experiments. The OPERA detector will be installed in the underground Gran Sasso Laboratory, 732 km away from CERN, where the CNGS (CERN neutrino beam to Gran Sasso) ν_π beam will be produced. The signature of the presence of ν_τ's in the ν_π beam will be the detection of τ leptons produced by ν_τ interactions. Nuclear emulsions will be used for precise event reconstruction, while electronic detectors will be used for triggering.     

Search for the νμ → ντ oscillation with the OPERA hybrid detector

This work reviews the status of the international OPERA experiment aimed at searching for the ν_μ → ν_τ oscillation. Development of the emulsion techniques in the preceding DONUT and CHORUS experiments is described. A brief overview of the NOMAD experiment is given, in which properties of ν_τ interactions were thoroughly investigated. Characteristics of the CERN-Gran Sasso (CNGS) neutrino beam are given, the structure of the OPERA hybrid detector and the functions of its subsystems are considered, and the automatic emulsion scanning technique is briefly reviewed. Uncertainties in reconstruction of event parameters using the electronic and emulsion detectors are discussed and the procedure adopted in the experiment for identification of ν_τ interactions is described. The main sources of background in the search for ν_μ → ν_τ oscillation are considered. Topologies of the first two ν_τ candidates observed in the OPERA emulsion detector are presented. Possibilities of increasing the ν_τ interaction selection efficiency using multidimensional criteria are briefly discussed.     

The infrared spectrum of C3O2: The interaction between ν7 and the ν2 and ν4 vibrations

The 3ν¹₇, 3ν³₇, and 4ν⁰₇ hot bands of the ν₄ fundamental of C₃O₂ in the 1580 cm^?1 region were analyzed from tunable diode laser spectra and the ground state to ν₄ + 2ν⁰₇ band at 1644 cm^?1 from Fourier transform spectra (FTS). The molecular constants for all of the v₄ 1 ← 0 bands as well as the intensity of the ν₀ + 2ν⁰₇ sum band relative to the ν₄ fundamental were in agreement with the predictions of the model of Weber and Ford. FTS spectra at 0.05 cm^?1 resolution were obtained of the sum and difference bands of ν₂ with ν₇ in the 750–900 cm^?1 region. Sharp Q branches occur for each ν₇ state in the sum bands, but only a number of R-branch bandheads and no recognizable Q branches in the difference bands. Assignments of the sum band Q branches through v₇ = 6 were made and molecular constants were determined for the ν₂ + ν¹₇ ← 0 transition at 819.7 cm^?1. The ν₇ potential function in the v₂ = 1 state was found to have a 1.2 cm^?1 barrier with a minimum at α = 4.9°, where 2α is the angular deviation from linearity. The Q-branch positions predicted from the calculated energy levels fit those observed within several cm^?1.     

Rotational and vibrational states in 115Te

High-spin states of the ¹¹⁵Te were studied by in-beam spectroscopy with the ⁸⁹Y (²⁹Si, p2n) fusion-evaporation reaction at a beam energy of 108 MeV. γ?γ coincidence and γ?γ angular correlation analyses were employed for determining the level scheme of ¹¹⁵Te. We have identified two vibrational-like bands built on the νh_11/2 and νg_7/2 quasiparticle states and the noncollective oblate states from the full alignment of quasiparticle configurations. In addition, a regular ΔI = 2 sequence with positive-parity was found for the first time in odd-A Te nuclei. This sequence is interpreted as a deformed structure resulting from three-quasiparticle alignment having the [π(g_7/2, h _11/2) ? ν(h _11/2)] configuration. Calculations of total Routhian surfaces and cranked shell model were performed and were used for assigning quasiparticle configurations to the states in ¹¹⁵Te.     

Infrared spectrum of formaldehyde: Coriolis interactions in the combination bands ν2 + ν6 and ν2 + ν3

A high-resolution infrared spectrum of H₂CO was measured in the range from 2600 to 3300 cm^?1. Vibration-rotation lines assigned to the combination bands ν₂ + ν₃ (a-type) and ν₂ + ν₆ (b-type) were analyzed as asymmetric-rotor bands by taking account of the Coriolis interactions among the ν₂ + ν₃, ν₂ + ν₆, and ν₂ + ν₄ states, though none of the ν₂ + ν₄ band lines have yet been definitely identified. The main results in cm^?1 units (with 2.5 times standard errors in the last digits given in parentheses) are: ν₀ = 3238.45(1), A - B?= 8.252(3), B?= 1.2053(2), and B - C = 0.1719 (assumed) for ν₂ + ν₃; ν₀ = 3000.10(1), A - B?= 8.125(46), B?= 1.2075(5), and B - C = 0.1693(14) for ν₂ + ν₆; and ν₀ = 2904.6(48), A - B?= 8.225(54), B?= 1.2023(20), and B - C = 0.1522 (assumed) for ν₂ + ν₄; the effective Coriolis interaction terms are: ξ_26,24^a = 10.10(3)cm^?1 and ξ_23,26^c = 0.96(3)cm^?1 under the assumption that ξ_23,24^b = 1.2841cm^?1. A second combination band 2ν₂ + ν₆ measured with lower resolution gave ν₀ = 4734.81(6)cm^?1.     

High-Resolution FTIR Spectra of CD2Cl2: Analysis of the ν3/ν7/ν9 Triad

The infrared spectra of isotopically pure CD₂³⁵Cl₂ have been recorded at a resolution of 0.0026 cm⁻¹ (FWHM) in the range 600-1160 cm⁻¹ with a Bruker IFS 120 HR Fourier transform interferometer. The absorption between 670 and 750 cm⁻¹ is due to three fundamentals, ν₃ (weak), ν₇ (very weak), and ν₉ (strong). A satisfactory analysis of the observed spectra has been obtained by including a c-Coriolis coupling between ν₃ and ν₉ and a b-Coriolis term between ν₇ and ν₉. Although no transitions could be observed for the very weak ν₇ band, its band origin could be estimated from the Coriolis interaction with ν₉. From the analysis of about 4200 assigned transitions of the ν₃ and ν₉ bands, excited state constants have been determined up to sextic terms. The Coriolis parameters obtained are compared to those calculated from a harmonic force field.     

The two-dimensional anharmonic oscillator: The CCC bending mode of C3O2

Newly observed data on the rotational constants of carbon su?ide in excited vibrational states of the low-wavenumber bending vibration ν₇ have been successfully interpreted in terms of the two-dimensional anharmonic oscillator wavefunctions associated with this vibration. By combining these results with published infrared and Raman spectra the vibrational assignment has been extended and a refined bending potential for ν₇ has been derived: this has a minimum at a bending angle of about 24° at the central C atom, with an energy maximum at the linear configuration some 23 cm^?1 above the minimum. From similar data on the combination and hot bands of ν₇ with ν₄ (1587 cm^?1) and ν₂ (786 cm^?1) the effective ν₇ bending potential has also been determined in the one-quantum excited states of ν₄ and ν₂. The effective ν₇ potential shows significant changes from the ground vibrational state; the central hump in the ν₇ potential surface is increased to about 50 cm^?1 in the v₄ = 1 state, and decreased to about 1 cm^?1 in the v₂ = 1 state. In the light of these results vibrational assignments are suggested for most of the observed bands in the infrared and Raman spectra of C₃O₂.     

Neutrino-astrophysics,nuclear physics,and particle physics at intense,pulsed, stopped-pion sources

Intense pulsed proton beams of ～ 1 GeV impinging on high-Z targets are intense sources of ν_μ from the (τ=26 ns) decay of π⁺, and \(\bar \nu _\mu \) and ν_e from the stopped μ⁺ decays. A pulse structure, narrow in time, allows the separation of reactions due to ν_μ from those from reactions involving \(\bar \nu _\mu\) and ν_e. The energy spectra are in the energy range of interest to nuclear astrophysics. A number of possible experiments relevant to solar neutrinos, supernovae collapse, weak interactions in nuclei, and intrinsic properties of neutrinos are discussed.     

High resolution infrared spectrum of the ν4 band of DCCF

The bending vibration-rotation band ν₄ of DCCF was studied. The measurements were carried out with a Fourier spectrometer at a resolution of about 0.03 cm^?1. The constants B₀=0.29141(1)cm^?1, α₄=?5.02(2)×10^?4cm^?1, q₄=4.52(3)×10^?4cm^?1, and D₀=9.2(4)×10^?8cm^?1 were derived. The rotational analysis of the “hot” bands 2ν₄(Δ) ← ν₄(II) and 2ν₄(Σ⁺) ← ν₄(II) was performed. In addition, the “hot” bands ν₄ + ν₅ ← ν₅ were assigned. A set of vibrational constants involved was derived.     

Heavy leptons,lepton mixing,and nonconservation of lepton-type number

Introducing a new weak doublet of heavy leptons, one is led to a mixing of the various lepton states with respect to the weak interaction and subsequently to the violation of electron and muon number conservation (e.g., the decay μ→eγ). The new charged lepton can only decay via such a mixing and is therefore relatively long-lived (τ>10^?11 sec). It can be produced singly in ν_μ nucleus scattering at high energies. Various other phenomenological consequences are discussed.     

High-Resolution Analysis of the ν6, ν17, and ν21 Bands of Dimethyl Ether

The ν₆, ν₁₇, and ν₂₁ fundamental bands of dimethyl ether have been assigned and rotationally analyzed. The spectra used were recorded at 0.005 cm⁻¹ spectral resolution with a Fourier-transform spectrometer coupled to a supersonic molecular beam leading to a rotational temperature of about 70 K. The ν₆ and ν₂₁ bands do not seem to be perturbed and the analysis of the rotational structure leads to band centers located at 933.906 6(9) and 1 103.951(1) cm⁻¹, respectively, and to accurate rotational and centrifugal distortion constants. For the ν₁₇ band at 2817.385(2) cm⁻¹, only the P and R branches could be assigned.     

Intracavity spectroscopy of high-temperature water vapor in the region of 1.06 μm

The absorption spectrum of water vapor is studied in the region of 9375–9460 cm^?1 and at temperatures within 300–1200 K using an intracavity laser spectrometer based on a Nd laser having a threshold absorption sensitivity of 10^?8 cm^?1. More than 270 absorption lines are detected in the high-temperature spectrum of water vapor, 70% of which are assigned to ten vibrational bands: 3ν₂ + ν₃, 2ν₁ + ν₂, ν₁ + ν₂ + ν₃, ν₂ + 2ν₃, ν₁ + 3ν₂, 3ν₃ ? ν₂, 2ν₂ + 2ν₃ ? ν₂, ν₁ + 2ν₂ + ν₃ ? ν₂, 2ν₁ + ν₃ ? ν₂, and ν₂ + 3ν₃ ? 2ν₂. The vibrational-rotational energy levels are determined.     

High-Resolution Infrared Spectrum of PH2Br: Rotational Analysis of the ν3 and ν4 Bands

The infrared spectrum of short-lived PH₂Br has been observed by studying the reaction of P₂H₄ with gaseous HBr. The a-type fundamental bands ν₃ at 812 cm⁻¹ and ν₄ at 399 cm⁻¹ have been recorded with a resolution of ca. 5×10⁻³ cm⁻¹, and their rotational fine structure has been observed. While the ν₄ band and its hot band 2ν₄−ν₄ associated with the P-Br stretching reveal compact ^qP and ^qRJ-clusters, the HPBr bending fundamental ν₃ shows a widely dispersed structure. A c-type Coriolis interaction of ν₃ (K_a) with the unobserved ν₆ state (K_a+1) at 795 cm⁻¹, with resonance between K_a=1 and 2, was detected and analyzed. Comparison with results of ab initio calculations revealed in general excellent agreement.     

ν<Subscript>μ</Subscript> → ν<Subscript> <Emphasis Type="Italic">e</Emphasis> </Subscript> oscillations search in the OPERA experiment

The tracking capabilities of the OPERA detector allow to reconstruct τ-leptons and electrons. It gives a possibility to observe ν_μ → ν_τ oscillations in the appearance mode and to study ν_μ → ν_e oscillations in the ν_μ CNGS beam. Current results on ν_μ → ν_e channel in the three-flavour mixing model are presented. The same data allow to constrain the presence of additional sterile neutrino states. The analysis of the full 2008–2012 OPERA data set and work on its improvement are going on. Details of the achievements are presented.     

Effects of conformation and hydrogen bonding on the CC and NCN stretching Raman bands of N‐deuterated histidinium

Histidine is an important and versatile amino acid residue that plays a variety of structural and functional roles in proteins. Although the Raman bands of histidine are generally weak, histidine in the N‐deuterated cationic form with imidazole N_π D and N_τ D bonds (N‐deuterated histidinium) gives two strong Raman bands assignable to the C₄C₅ stretch (ν_CC) and the N_π C₂ N_τ symmetric stretch (ν_NCN) of the imidazole ring. We examined the Raman spectra of N‐deuterated histidinium in 12 crystals with known structures. The observed ν_CC and ν_NCN wavenumbers were analyzed to find empirical correlations with the conformation and hydrogen bonding. The effect of conformation on the vibrational wavenumber was expressed as a threefold cosine function of the C_α C_β C₄C₅ torsional angle. The effect of hydrogen bonding at N_π or N_τ was assumed to be proportional to the inverse sixth power of the distance between the hydrogen and acceptor atoms. Multiple linear regression analysis clearly shows that the conformational effect on the vibrational wavenumber is comparable for ν_CC and ν_NCN. The hydrogen bond at N_π weakly lowers the ν_CC wavenumber and substantially raises the ν_NCN wavenumber. On the other hand, the hydrogen bond at N_τ strongly raises the ν_CC wavenumber but does not affect the ν_NCN wavenumber. These empirical correlations may be useful in Raman spectral analysis of the conformation and hydrogen bonding states of histidine residues in proteins. Copyright © 2010 John Wiley & Sons, Ltd.