939 research outputs found
Motion of a Vector Particle in a Curved Spacetime. I. Lagrangian Approach
From the simple Lagrangian the equations of motion for the particle with spin
are derived. The spin is shown to be conserved on the particle world-line. In
the absence of a spin the equation coincides with that of a geodesic. The
equations of motion are valid for massless particles as well, since mass does
not enter the equations explicitely.Comment: 6 pages, uses mpla1.sty, published in MPLA, replaced with corrected
typo
Superconducting microstrip detectors
Superconducting NbN microstrip counters feature radiation hardness two orders of magnitude higher than conventional Si strip detectors, spatial resolution limited only by lithographic techniques (0.1 - 2 microns), intrinsic signal rise time of 2 ps, and signal transport over large distances without losses. The aim of this proposal is to improve understanding of the physics of such detectors and to establish their large- scale feasibility
Sterile Neutrinos, Coherent Scattering and Oscillometry Measurements with Low-temperature Bolometers
Coherent neutrino-nucleon scattering offers a unique approach in the search
for physics beyond the Standard Model. When used in conjunction with
mono-energetic neutrino sources, the technique can be sensitive to the
existence of light sterile neutrinos. The ability to utilize such reactions has
been limited in the past due to the extremely low energy threshold (10-50 eV)
needed for detection. In this paper, we discuss an optimization of cryogenic
solid state bolometers that enables reaching extremely low kinetic energy
thresholds. We investigate the sensitivity of an array of such detectors to
neutrino oscillations to sterile states. A recent analysis of available reactor
data appears to favor the existence of such such a sterile neutrino with a mass
splitting of eV and mixing strength of
at 95% C.L. An array of such
low-threshold detectors would be able to make a definitive statement as to the
validity of the interpretation.Comment: 14 pages, 10 figures. Version 2: Temperature dependence on alpha
fixed from earlier versio
Superconducting NbN microstrip detectors
Superconducting NbN strip transmission line counters and coupling circuits were processed on silicon wafers using thin film techniques, and they were characterized with several methods to verify the design principles. The stripline circuits, designed using microwave design rules, were simulated using a circuit design tool enhanced to include modelling of the superconducting lines. The strips, etched out of the 282 nm thick top NbN film with resistivity 284 ”?cm at 20 K, have critical temperatures in the range 12 to 13 K and a critical current density approximately Jc(0) = 3.3·105 A/cm2. The linearized heat transfer coefficient between the strip and the substrate is approximately 1.1·105 W/(m2K) and the healing length is about 1.6 ”m between 3 and 5 K temperatures. Traversing 5 MeV a-particles caused the strips to quench. No events due to electrons could be detected in agreement with the predicted signal amplitude which is below the noise threshold of our wideband circuitry. The strip bias current and hence the signal amplitude were limited due to a microbridge at the isolator step of the impedance transformer
Low-saturated-fat and low-cholesterol diet does not alter pubertal development and hormonal status in adolescents
Large enhancement of deuteron polarization with frequency modulated microwaves
We report a large enhancement of 1.7 in deuteron polarization up to values of
0.6 due to frequency modulation of the polarizing microwaves in a two liters
polarized target using the method of dynamic nuclear polarization. This target
was used during a deep inelastic polarized muon-deuteron scattering experiment
at CERN. Measurements of the electron paramagnetic resonance absorption spectra
show that frequency modulation gives rise to additional microwave absorption in
the spectral wings. Although these results are not understood theoretically,
they may provide a useful testing ground for the deeper understanding of
dynamic nuclear polarization.Comment: 10 pages, including the figures coming in uuencoded compressed tar
files in poltar.uu, which also brings cernart.sty and crna12.sty files neede
Results and perspectives of the solar axion search with the CAST experiment
The status of the solar axion search with the CERN Axion Solar Telescope
(CAST) will be presented. Recent results obtained by the use of He as a
buffer gas has allowed us to extend our sensitivity to higher axion masses than
our previous measurements with He. With about 1 h of data taking at each of
252 different pressure settings we have scanned the axion mass range 0.39 eV 0.64 eV. From the absence of an excess of x rays when the
magnet was pointing to the Sun we set a typical upper limit on the axion-photon
coupling of g GeV at 95% C.L., the
exact value depending on the pressure setting. CAST published results represent
the best experimental limit on the photon couplings to axions and other similar
exotic particles dubbed WISPs (Weakly Interacting Slim Particles) in the
considered mass range and for the first time the limit enters the region
favored by QCD axion models. Preliminary sensitivities for axion masses up to
1.16 eV will also be shown reaching mean upper limits on the axion-photon
coupling of g GeV at 95% C.L.
Expected sensibilities for the extension of the CAST program up to 2014 will be
presented. Moreover long term options for a new helioscope experiment will be
evoked.Comment: 4 pages, 2 pages, to appear in the proceedings of the 24th Rencontres
de Blois V2 A few affiliations were not corrected in previous version V3
Author adde
Polarized neutron scattering by polarized protons of bovine serum albumin in deuterated solvent
Effects of Randomized Controlled Infancy-Onset Dietary Intervention on Leukocyte Telomere LengthâThe Special Turku Coronary Risk Factor Intervention Project (STRIP)
Reduced telomere length (TL) is a biological marker of aging. A high inter-individual variation in TL exists already in childhood, which is partly explained by genetics, but also by lifestyle factors. We examined the influence of a 20-year dietary/lifestyle intervention on TL attrition from childhood to early adulthood. The study comprised participants of the longitudinal randomized Special Turku Coronary Risk Factor Intervention Project (STRIP) conducted between 1990 and 2011. Healthy 7-month-old children were randomized to the intervention group (n = 540) receiving dietary counseling mainly focused on dietary fat quality and to the control group (n = 522). Leukocyte TL was measured using the Southern blot method from whole blood samples collected twice: at a mean age of 7.5 and 19.8 years (n = 232; intervention n = 108, control n = 124). Yearly TL attrition rate was calculated. The participants of the intervention group had slower yearly TL attrition rate compared to the controls (intervention: mean = â7.5 bp/year, SD = 24.4 vs. control: mean = â15.0 bp/year, SD = 30.3; age, sex and baseline TL adjusted ÎČ = 0.007, SE = 0.004, p = 0.040). The result became stronger after additional adjustments for dietary fat quality and fiber intake, serum lipid and insulin concentrations, systolic blood pressure, physical activity and smoking (ÎČ = 0.013, SE = 0.005, p = 0.009). A long-term intervention focused mainly on dietary fat quality may affect the yearly TL attrition rate in healthy children/adolescents
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