5001215
Measurement of neutrino oscillation with KamLAND: evidence of spectral distortion.
We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 nu (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor nu (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from nu (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2) and tan((2)theta=0.40(+0.10)(-0.07), the most precise determination to date.
56005177
Inclusive J production in Z0 decays
Abstract Inclusive J production in Z0 decays is observed via the leptonic decay mode J → l+l− (l = e,μ). We measure the branching ratio Br(Z0 → J + X) = (4.1 ± 0.7 (stat.) ± 0.3 (sys.)) × 10−3. We have calculated the fraction of the J mesons from b-hadron decay and find a branching ratio of Br(b → J + X)= (1.3±0.2(stat.)±0.2(sys.)) × 10−2. We determine the average fractional energy of bottom hadrons 〈XE > = 0.70±0.03 (stat.)+0.02−0.01 (sys.) using the momentum spectrum of the J mesons. From a study of the angle between the J and the most energetic jet, we set an upper limit on the branching ratio Br ( Z 0 → q q g ∗ ; g ∗ → J + X ) −4 at 90% confidence level.
18893994
The mass production and quality control of RPCs for the Daya Bay experiment
Abstract Resistive plate chambers will be used in the Daya Bay reactor neutrino experiment to help veto backgrounds created by cosmic-ray muons. The mass production of RPCs began in 2008 and by the end of 2009, 1600 RPCs (3500 m 2 ) had been produced and tested. This paper describes the production and quality control procedures, and quality assurance using cosmic-ray testing.
125677069
TUBE CHAMBERS FOR THE MUON FILTER OF THE L3 DETECTOR
122214277
A water Cherenkov calorimeter for long baseline neutrino oscillation experiments
Abstract We propose a water-based large homogeneous calorimeter as the next generation neutrino detector for ν factories and/or conventional ν beams. The Cherenkov light produced in water is sufficient to have good energy resolution, and the pattern recognition is realized by a modular water tank structure. Monte Carlo simulations show that the detector performance is excellent for identifying neutrino CC events while rejecting backgrounds.
118039047
Physics of tau and charm
The physics of tau and charm started in early 70's after J/$\psi$ and $\tau$ were discovered. Since then several dedicated accelerators and experiments were built with increasing luminosities and studies on light hadron spectroscopy, charmonium, electroweak and QCD were never interupted. New interests and surprises are not rare in this area. With the newly built BEPCII/BESIII, an even brighter future is foreseen.
34106953
Crosstalk research of long strip timing RPC
The time-of-flight (TOF) wall of CBM is proposed to be assembled with MRPCs. In a relative high particle multiplicity situation (about 20kHz/cm2), multi-hit capability is one of the most demanding requirement of the detector. Crosstalk is an important reason for the deterioration the multi-hit capability of a detector. To reduce the crosstalk level, a kind of shielded long-strip two-end readout MRPC was developed. 1mm width guard strips were added between strips of a 1m-long MRPC. Beam test with 2.5GeV protons was performed in GSI in August, 2009. Horizontal and vertical scans were done. Combined with data from silicon detector, we get the crosstalk between four neighbor strips. The results show that the crosstalk level can be reduced and double hits can affect the time resolution. It also shows that the crosstalk increase with high voltage and decrease with surface resistivity of electrode.
119289656
Testing quantum gravity effects with latest CMB observations
Abstract Inspired by quantum gravitational physics, the approach of non-commutative (NC) phase space leads to a modified dispersion relation of gravitational waves. This feature, if applied to the very early universe, gives rise to a modified power spectrum of primordial tensor perturbations with a suppression of power on large scales. We confront this phenomenon with the BICEP2 and Planck experiments, and show that inflation with the modified dispersion relation can simultaneously fit the observations better than the standard inflationary paradigm. In particular, the numerical result implies that with the latest cosmological microwave background (CMB) observations, a quantum gravity modified power spectrum of primordial tensor modes is preferred at a statistical significance of more than 3 σ compared with the minimal model. Our study indicates that the potential tension between the BICEP2 and Planck data may be resolved by quantum gravity effects.
119291496
A covering theory of special relativity
Abstract: Under the assumption of closed-path velocity of light invariant, we show both thegeneral expression of velocity of light in an ordinary inertial reference frame and the generalizedLorentz transformation between the ordinary inertial reference frame and the absolute privilegedreference frame. Although such assumption cannot determine theory unambiguously, somesigniﬁcant results can still be obtained by the assumption. Furthermore, the study shows that therelativity of simultaneity is not a universal concept. © 2011 Physics Essays Publication . DOI: 10.4006/1.3589801 Re´sume´: Dans l’hypothese de l’invariabilite de la vitesse de lumiere dans un chemin ferme, onobtient soit l’expression generale de la vitesse de la lumiere dans un cadre referentiel inertielordinaire, soit la transformation de Lorentz generalisee entre le cadre referentiel inertiel ordinaire etcelui-la absolue privilegie . Bien que cette hypothese ne soit pas sufﬁsante pour determiner latheorie sans ambiguite, on peut avoir quand meme certains resultats importants. En plus, l’etudemontre que la relativite de la simultaneite n’est pas un concept universel.
121847945
NEUTRINO ASTRONOMY AND COSMIC RAYS AT THE SOUTH POLE: LATEST RESULTS FROM AMANDA AND PERSPECTIVES FOR ICECUBE
The AMANDA neutrino telescope has been in operation at the South Pole since 1996. The present final array configuration, operational since 2000, consists of 677 photomultiplier tubes arranged in 19 strings, buried at depths between 1500 and 2000 m in the ice. The most recent results on a multi-year search for point sources of neutrinos will be shown. The study of events triggered in coincidence with the surface array SPASE and AMANDA provided a result on cosmic ray composition. Expected improvements from IceCube/IceTop will also be discussed.
18759679
Primordial power spectrum reconstruction
In order to reconstruct the initial conditions of the universe it is important to devise a method that can efficiently constrain the shape of the power spectrum of primordial matter density fluctuations in a model-independent way from data. In an earlier paper we proposed a method based on the wavelet expansion of the primordial power spectrum. The advantage of this method is that the orthogonality and multiresolution properties of wavelet basis functions enable information regarding the shape of Pin(k) to be encoded in a small number of non-zero coefficients. Any deviation from scale invariance can then be easily picked out. Here we apply this method to simulated data to demonstrate that it can accurately reconstruct an input Pin(k), and present a prescription for how this method should be used on future data.