Neutrino mass and unification

I discuss the implications of the observed masses and mixings of neutrinos for unification beyond the standard model and point out the important role that ongoing searches for the remaining mixing angle θ₁₃, neutrinoless double beta decay as well as possible searches for a Z^′ at LHC can play in this discussion.     

Single- and double-pion production in nucleon collisions on the nucleon and on nuclei—the ABC effect and its origin in a dibaryonic resonance

The ABC effect-an intriguing low-mass enhancement in the ππ invariant mass spectrum-is known from inclusive measurements of two-pion production in nuclear fusion reactions. First exclusive measurements carried out at CELSIUS-WASA for the fusion reactions leading to d or ³He reveal this effect to be a σ-channel phenomenon associated with the formation of a ΔΔ system in the intermediate state and combined with a resonance-like behavior in the total cross-section. Together with the observation that the differential distributions do not change in shape over the resonance region the features fulfill the criteria of an isoscalar s-channel resonance in pn and NNππ systems, if the two emitted nucleons are bound. It obviously is robust enough to survive in nuclei as a dibaryonic resonance configuration. In this context also the phenomenon of NΔ resonances is reexamined.     

Neutrino-nucleus reactions in terrestrial experiments and astrophysics

We focus on the role and importance of neutrino-nucleus interactions to neutrino detection by terrestrial detector-nuclei and to various processes as well as scattering effects occurring inside the matter of stars (supernova, etc.) that generate the astrophysical neutrino energy spectra. We specifically concentrate on the parameterizations of the supernova neutrino energy distributions and examine the use of the low-energy β-beam spectra, originating from the boosted radioactive nuclei ⁶He and ¹⁸Ne, for such purposes.     

Alpha decay chains from superheavy nuclei

Magic islands for extra-stable nuclei in the midst of the sea of fission-instability were predicted to be around Z=114, 124 or, 126 with N=184, and Z=120, with N=172. Whether these fission-survived superheavy nuclei with high Z and N would live long enough for detection or, undergo α-decay in a very short time, remains an open question. α-decay half lives of nuclei with 130≥Z≥100 have been calculated in a WKB framework using density-dependent M3Y interaction with Q-values from different mass formulae. The results are in excellent agreement with the experimental data. Fission survived Sg nuclei with Z=106, N=162 is predicted to have the highest α-decay half life (∼3.2 h) in the Z=106-108, N=160-164 region called small island/peninsula. Superheavy nuclei with Z>118 are found to have α-decay half lives of the order of microseconds or less.     

In-beam and decay spectroscopy of transfermium nuclei

In recent years the body of experimental data on nuclei with masses A?250 has increased dramatically. Nuclei that had been out of reach for experimental studies have now become available for study through a variety of approaches, both with in-beam spectroscopic methods and through spectroscopy following the decay of isomeric states or alpha decays at the focal plane of powerful separators. This article aims to collect the currently available experimental data on nuclei between Cm (Z=96) and Db (Z=105). The review of this data builds on the evaluations in the literature and focusses on those datasets obtained most recently.     

Spin-dependent nuclear weak processes and nucleosynthesis in stars

Spin dependent nuclear weak processes and nucleosynthesis in stars are investigated based on recent advances in shell model studies of stable and unstable exotic nuclei. Three topics on (1) neutrino-nucleus reactions in supernova explosions and nucleosynthesis of light elements as well as Mn, (2) electron capture reaction rates on Ni and Co isotopes at high densities and temperatures in the core-collapse process, and (3) new β-decay half-lives of N=126 isotones obtained by including both the Gamow-Teller and the first-forbidden transitions, and the effects on the element abundance in the r-process at the third peak region (A∼195), are studied with the use of new shell model Hamiltonians.     

Universality in bibliometrics

Many discussions have enlarged the literature in Bibliometrics since the Hirsch proposal, the so called h-index. Ranking papers according to their citations, this index quantifies a researcher only by its greatest possible number of papers that are cited at least h times. A closed formula for h-index distribution that can be applied for distinct databases is not yet known. In fact, to obtain such distribution, the knowledge of citation distribution of the authors and its specificities are required. Instead of dealing with researchers randomly chosen, here we address different groups based on distinct databases. The first group is composed of physicists and biologists, with data extracted from Institute of Scientific Information (ISI). The second group is composed of computer scientists, in which data were extracted from Google-Scholar system. In this paper, we obtain a general formula for the h-index probability density function (pdf) for groups of authors by using generalized exponentials in the context of escort probability. Our analysis includes the use of several statistical methods to estimate the necessary parameters. Also an exhaustive comparison among the possible candidate distributions are used to describe the way the citations are distributed among authors. The h-index pdf should be used to classify groups of researchers from a quantitative point of view, which is meaningfully interesting to eliminate obscure qualitative methods.     

Structural modifications of diamond like carbon films induced by MeV nitrogen ion irradiation

Diamond-like carbon (DLC) films were deposited on Si(1 0 0) substrates using plasma deposition technique. The deposited films were irradiated using 2 MeV N⁺ ions at fluences of 1×10¹⁴, 1×10¹⁵ and 5×10¹⁵ ions/cm². Samples have been characterized by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). Analysis of Raman spectra shows a gradual shift of both D and G band peaks towards higher frequencies along with an increase of the intensity ratio, I(D)/I(G), with increasing ion fluence in irradiation. These results are consistent with an increase of sp² bonding. XPS results also show a monotonic increase of sp²/sp³ hybridization ratio with increasing ion fluence. Plan view TEM images show the formation of clusters in the irradiated DLC films. HRTEM micrographs from the samples irradiated at a fluence of 5×10¹⁵ ions/cm² show the lattice image with an average interplanar spacing of 0.34 nm, revealing that the clusters are graphite clusters. The crystallographic planes in these clusters are somewhat distorted compared to the perfect graphite structure.     

Magnetic-field induced quantum critical points of valence transition in Ce- and Yb-based heavy fermions

The mechanism of how the magnetic field controls the critical end point of the first-order valence transition is clarified, which is essentially ascribed to charge degrees of freedom. It is shown that the quantum critical point is induced by applying the magnetic field, which explains a peculiar magnetic response in CeIrIn₅ and sharp contrast between X=Ag and Cd for YbXCu₄. Significance of the proximity of the first-order valence transition in the Ce- and Yb-based heavy fermions is pointed out.     

Proximity effects in a superconductor/ferromagnet junction

A proximity effect in an s-wave superconductor/ferromagnet (SC/F) junction is theoretically studied using the second order perturbation theory for the tunneling Hamiltonian and Green's function method. We calculate a pair amplitude induced by the proximity effect in a weak ferromagnetic metal (FM) and a half-metal (HM). In the SC/FM junction, it is found that a spin-singlet pair amplitude (Ψ_s) and spin-triplet pair amplitude (Ψ_t) are induced in FM and both amplitudes depend on the frequency in the Matsubara representation. Ψ_s is an even function and Ψ_t is an odd function with respect to the Matsubara frequency (ω_n). In the SC/HM junction, we examine the proximity effects by taking account of magnon excitations in HM. It is found that the triplet-pair correlation is induced in HM. The induced pair amplitude in HM shows a damped oscillation as a function of the position and contains the terms of even and odd functions of ω_n as in the case of the SC/FM junction. We discuss that in our tunneling model the pair amplitude of even function of ω_n only contributes to a Josephson current.     

Cusps in KL→3π decays

The pronounced cusp in K→3π decays which is generated by the pion mass difference is directly related to the ππS-wave scattering lengths. We apply a nonrelativistic effective field theory framework to evaluate the amplitudes for K_L→3π decays in a systematic manner. Electromagnetic effects in the neutral channel K_L→3π⁰ are also discussed.     

Generalised Tsallis statistics in electron-positron collisions

The scaling of charged hadron fragmentation functions to the Tsallis distribution for the momentum fraction 0.01?x?0.2 is presented for various e⁺e⁻ collision energies. A possible microcanonical generalisation of the Tsallis distribution is proposed, which gives good agreement with measured data up to x≈1. The proposal is based on superstatistics and a Koba-Nielsen-Olesen (KNO) like scaling of multiplicity distributions in e⁺e⁻ experiments.     

Nanoscale observations of the operational failure for phase-change-type nonvolatile memory devices using Ge2Sb2Te5 chalcogenide thin films

In this study, a phase-change memory device was fabricated and the origin of device failure mode was examined using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Ge₂Sb₂Te₅ (GST) was used as the active phase-change material in the memory device and the active pore size was designed to be 0.5 m. After the programming signals of more than 2×10⁶ cycles were repeatedly applied to the device, the high-resistance memory state (reset) could not be rewritten and the cell resistance was fixed at the low-resistance state (set). Based on TEM and EDS studies, Sb excess and Ge deficiency in the device operating region had a strong effect on device reliability, especially under endurance-demanding conditions. An abnormal segregation and oxidation of Ge also was observed in the region between the device operating and inactive peripheral regions. To guarantee an data endurability of more than 1×10¹⁰ cycles of PRAM, it is very important to develop phase-change materials with more stable compositions and to reduce the current required for programming.     

Prospects of reactor neutrino experiments

Since the energy of a reactor neutrino is a few MeV, all , and oscillations are accessible by reactor neutrino experiments. KamLAND observed the oscillation and currently Double Chooz, RENO and Dayabay experiments are under construction aiming to detect oscillation. There are still good prospects for future reactor neutrino experiments after them. For example, there is room to further improve sin²2θ₁₃ accuracy at a baseline of ∼1.5 km, a very precise sin²2θ₁₂ measurement and the determination of mass hierarchy may be possible at a baseline ∼50 km, and if KamLAND is enlarged to the SuperKamiokande size, better measurement of and sin²2θ₁₂ will be anticipated. It is important to take into account such possibilities when planning future neutrino program after θ₁₃ is measured by current experiments.     

Nuclear matrix elements for rare decays

Neutrinoless double electron capture (0νECEC) is being vigorously investigated because of the possibility of it telling us something about the absolute mass scale of the neutrino. The resonant 0νECEC is particularly interesting due to the potentially huge enhancement of its decay rate by a resonance condition. Recently the mass differences of two atom pairs were measured in order to study the enhancement of the 0νECEC rates of ⁷⁴Se and ¹¹²Sn. The associated nuclear matrix elements were also evaluated. The neutrino mass can also be detected by using beta decays with low Q values. Related to this we have investigated the second-forbidden decay branch of ¹¹⁵In with its ultra-low Q value. Open questions about nuclear and atomic contributions to the associated decay rate emerge.     

Mean wind: Its velocity and temperature fluctuation in low-Prandtl-number thermal convection

Large-scale circulation in the confined thermal turbulence of mercury is studied experimentally. The instantaneous velocity profile at 128 points is directly measured using ultrasonic velocimetry and the temperature fluctuation is simultaneously obtained by a small thermistor at the cell center. The periodic velocity oscillation is observed for aspect ratios Γ=1,2, but for Γ=0.5. The temperature oscillation is confirmed only in the Γ=2 cell. It is found that the flow patterns depending on the aspect ratio are characterized sufficiently by the joint probability density function up to Ra=4×10⁸.     

The status of KATRIN

KATRIN will have the capability to push the limit on the mass of the electron anti-neutrino to 200 meV (90% C.L.) by investigating the kinematics of the electrons from tritium β decay very close to the endpoint of the β spectrum. The importance of this experiment will be discussed in various contributions to this school. KATRIN is currently under construction at KIT (Karlsruhe Institute of Technology). This talk gives an overview over the status of KATRIN with emphasis on the aspects of KATRIN not covered by the talks following this one.     

Soft x-ray PHA measurement of the long pulse discharge in HT-7 tokamak

By analyzing the soft x-ray energy spectrum measured by the soft x-ray pulse height analysis (PHA) system, the electron temperature (Te) and the effective charge number (Zeff) of the ultra-long pulse discharge driven by lower hybrid wave (LHW) were obtained in the HT-7 tokamak. Moreover, the information of medium-Z impurities such as Ti, Cr, Fe, and Ni intrinsic to HT-7 tokamak can also be inspected. The accuracy of the electron temperature derived from the soft x-ray energy spectrum measurements is verified by comparing with the temperature measured by the Thomson scattering system for various plasmas and electron cyclotron emission diagnostic system for ohmic plasmas. The bulk electron temperature of about 1 keV and Zeff≈2 were achieved for long pulse plasma. The appreciable Kα lines of Ti, Cr, Fe and Ni metallic impurities released from the antennas of radio frequency wave and/or the first wall and Ar injected into plasma can be observed, and they kept stable during the long duration discharges. As a result, the longest pulse discharge with relatively high temperature of Te(0)∼1 keV, and ne(0)∼0.5×¹⁰¹⁹ m−3 has been achieved with a duration of 400 s in the HT-7 experimental campaign in 2008.