18098456
A broad-band FT-ICR Penning trap system for KATRIN
The KArlsruhe TRItium Neutrino experiment KATRIN aims at improving the upper limit of the mass of the electron antineutrino to about 0.2 eV (90% c.l.) by investigating theβ-decay of tritium gas molecules T2→ ( 3 HeT) + + e − + ¯ νe. The experiment is currently under construction to start firs t data taking in 2012. One source of systematic uncertainties in the KATRIN experiment is the formation of ion clusters when tritium decays and decay products interact with residual tritium molecules. It is essential to monitor the a bundances of these clusters since they have different final state energies than tritium ions. For this purpose, a protot ype of a cylindrical Penning trap has been constructed and tested at the Max-Planck-Institute for Nuclear Physics in Heidelberg, which will be installed in the KATRIN beam line. This system employs the technique of Fourier-Transform Ion-Cyclotron-Resonance in order to measure the abundances of the different stored ion species.
14807424
TRIGA-SPEC: A setup for mass spectrometry and laser spectroscopy at the research reactor TRIGA Mainz
Abstract The research reactor TRIGA Mainz is an ideal facility to provide neutron-rich nuclides with production rates sufficiently large for mass spectrometric and laser spectroscopic studies. Within the TRIGA-SPEC project, a Penning trap as well as a beamline for collinear laser spectroscopy are being installed. Several new developments will ensure high sensitivity of the trap setup enabling mass measurements even on a single ion. Besides neutron-rich fission products produced in the reactor, also heavy nuclides such as 235 U or 252 Cf can be investigated for the first time with an off-line ion source. The data provided by the mass measurements will be of interest for astrophysical calculations on the rapid neutron-capture process as well as for tests of mass models in the heavy-mass region. The laser spectroscopic measurements will yield model-independent information on nuclear ground-state properties such as nuclear moments and charge radii of neutron-rich nuclei of refractory elements far from stability. TRIGA-SPEC also serves as a test facility for mass and laser spectroscopic experiments at SHIPTRAP and the low-energy branch of the future GSI facility FAIR. This publication describes the experimental setup as well as its present status.
53658744
Q value and half-life of double-electron capture in 184Os
The observation of neutrinoless double-beta transitionswould reveal physics beyond the Standard Model, asit would establish neutrinos to be Majorana particles,which implies a violation of the lepton number conserva-tion. Experiments searching for these transitions have fo-cused on the detection of neutrinoless double-beta decay(0 ) rather than neutrinoless double-electron capture(0). One reason among others is in general the sig-ni cantly shorter half-life of the 0 process. However,in the case of neutrinoless double-electron capture, thetransition is expected to be resonantly enhanced if theinitial and the nal state of the transition are degeneratein energy [1{3].In this work, we investigate neutrinoless double-electron capture in
122032402
High-frequency Ramsey excitation in a Penning trap
The Ramsey excitation method for high-precision mass-measurements of highly-charged ions has been investigated and benchmarked using H2+ ions in the Penning-trap mass-spectrometer SMILETRAP. The reason for using H2+ ions are their high cyclotron frequency which is typical for the highly-charged ions usually used at SMILETRAP. Two-, three- and four-pulse Ramsey excitation data are analyzed with the help of recent theoretical work and are compared with the previously used single-pulse excitation data. An improvement factor of 2.9 in the statistical uncertainty is achieved. Furthermore the mass of 76Se, included in the previous Q-value measurement of the 76Ge neutrinoless double beta decay, is checked using 76Se25+ ions and a three-pulse Ramsey excitation. The results show a convincing agreement with the measurement when using single-pulse excitation and therefore our Q-value of 2039.006(50) keV, performed with single-pulse excitation, is confirmed.
18678380
Position-sensitive ion detection in precision Penning trap mass spectrometry
A commercial, position-sensitive ion detector was used for the first time for the time-of-flight ion-cyclotron resonance detection technique in Penning trap mass spectrometry. In this work, the characteristics of the detector and its implementation in a Penning trap mass spectrometer will be presented. In addition, simulations and experimental studies concerning the observation of ions ejected from a Penning trap are described. This will allow for a precise monitoring of the state of ion motion in the trap.
119181705
AN HST/WFC3-IR MORPHOLOGICAL SURVEY OF GALAXIES AT z = 1.5-3.6. I. SURVEY DESCRIPTION AND MORPHOLOGICAL PROPERTIES OF STAR-FORMING GALAXIES*
We present the results of a 42-orbit Hubble Space Telescope Wide-Field Camera 3 (HST/WFC3) survey of the rest-frame optical morphologies of star-forming galaxies with spectroscopic redshifts in the range z = 1.5-3.6. The survey consists of 42 orbits of F160W imaging covering ~65 arcmin2 distributed widely across the sky and reaching a depth of 27.9 AB for a 5σ detection within a 0.2 arcsec radius aperture. Focusing on an optically selected sample of 306 star-forming galaxies with stellar masses in the range M_* = 10^9-10^(11) M_☉, we find that typical circularized effective half-light radii range from ~0.7 to 3.0 kpc and describe a stellar mass-radius relation as early as z ~ 3. While these galaxies are best described by an exponential surface brightness profile (Sersic index n ~ 1), their distribution of axis ratios is strongly inconsistent with a population of inclined exponential disks and is better reproduced by triaxial stellar systems with minor/major and intermediate/major axis ratios ~0.3 and 0.7, respectively. While rest-UV and rest-optical morphologies are generally similar for a subset of galaxies with HST/Advanced Camera for Surveys imaging data, differences are more pronounced at higher masses M_* > 3 × 10^(10) M_☉. Finally, we discuss galaxy morphology in the context of efforts to constrain the merger fraction, finding that morphologically identified mergers/non-mergers generally have insignificant differences in terms of physical observables such as stellar mass and star formation rate, although merger-like galaxies selected according to some criteria have statistically smaller effective radii and correspondingly larger Σ_(SFR).
11500580
Renormalization-group analysis of layered sine-Gordon type models
Abstract We analyze the phase structure and the renormalization group (RG) flow of the generalized sine-Gordon models with nonvanishing mass terms, using the Wegner–Houghton RG method in the local potential approximation. Particular emphasis is laid upon the layered sine-Gordon (LSG) model, which is the bosonized version of the multi-flavour Schwinger model and approaches the sum of two “normal”, massless sine-Gordon (SG) models in the limit of a vanishing interlayer coupling J . Another model of interest is the massive sine-Gordon (MSG) model. The leading-order approximation to the UV (ultraviolet) RG flow predicts two phases for the LSG as well as for the MSG, just as it would be expected for the SG model, where the two phases are known to be separated by the Coleman fixed point. The presence of finite mass terms (for the LSG and the MSG) leads to corrections to the UV RG flow, which are naturally identified as the “mass corrections”. The leading-order mass corrections are shown to have the following consequences: (i) for the MSG model, only one phase persists, and (ii) for the LSG model, the transition temperature is modified. Within the mass-corrected UV scaling laws, the limit of J → 0 is thus nonuniform with respect to the phase structure of the model. The modified phase structure of general massive sine-Gordon models is connected with the breaking of symmetries in the internal space spanned by the field variables. For the LSG, the second-order subleading mass corrections suggest that there exists a cross-over regime before the IR scaling sets in, and the nonlinear terms show explicitly that higher-order Fourier modes appear in the periodic blocked potential.
85464497
Functional renormalization group for quantized anharmonic oscillator
Abstract Functional renormalization group methods formulated in the real-time formalism are applied to the O ( N ) symmetric quantum anharmonic oscillator, considered as a 0 + 1 dimensional quantum field-theoric model, in the next-to-leading order of the gradient expansion of the one- and two-particle irreducible effective action. The infrared scaling laws and the sensitivity-matrix analysis show the existence of only a single, symmetric phase. The Taylor expansion for the local potential converges fast while it is found not to work for the field-dependent wavefunction renormalization, in particular for the double-well bare potential. Results for the gap energy for the bare anharmonic oscillator potential hint on improving scheme-independence in the next-to-leading order of the gradient expansion, although the truncated perturbation expansion in the bare quartic coupling provides strongly scheme-dependent results for the infrared limits of the running couplings.
115135571
A magic pyramid of supergravities
A bstractBy formulating $ \mathcal{N} $ = 1, 2, 4, 8, D = 3, Yang-Mills with a single Lagrangian and single set of transformation rules, but with fields valued respectively in $ \mathbb{R},\mathbb{C},\mathbb{H},\mathbb{O} $, it was recently shown that tensoring left and right multiplets yields a Freudenthal-Rosenfeld-Tits magic square of D = 3 supergravities. This was subsequently tied in with the more familiar $ \mathbb{R},\mathbb{C},\mathbb{H},\mathbb{O} $ description of spacetime to give a unified division-algebraic description of extended super Yang-Mills in D = 3, 4, 6, 10. Here, these constructions are brought together resulting in a magic pyramid of supergravities. The base of the pyramid in D = 3 is the known 4 × 4 magic square, while the higher levels are comprised of a 3 × 3 square in D = 4, a 2 × 2 square in D = 6 and Type II supergravity at the apex in D = 10. The corresponding U-duality groups are given by a new algebraic structure, the magic pyramid formula, which may be regarded as being defined over three division algebras, one for spacetime and each of the left/right Yang-Mills multiplets. We also construct a conformal magic pyramid by tensoring conformal supermultiplets in D = 3, 4, 6. The missing entry in D = 10 is suggestive of anexotic theory with G/H duality structure F4(4)/Sp(3) × Sp(1).
55685041
Infrared fixed point in quantum Einstein gravity
A bstractWe performed the renormalization group analysis of the quantum Einstein gravity in the deep infrared regime for different types of extensions of the model. It is shown that an attractive infrared point exists in the broken symmetric phase of the model. It is also shown that due to the Gaussian fixed point the IR critical exponent ν of the correlation length is 1/2. However, there exists a certain extension of the model which gives finite correlation length in the broken symmetric phase. It typically appears in case of models possessing a first order phase transitions as is demonstrated on the example of the scalar field theory with a Coleman-Weinberg potential.