The discrete contribution to ψ′→J/ψ+γγ\psi^{\prime}\to J/\psi+\gamma\gamma

The decay mode $\psi(2S)\to J/\psi+\gamma\gamma$ is proposed in order to experimentally identify the effects of the coupling of charmonium states to the continuum $D\bar D$ states. To have a better understanding of such a two-photon decay process, in this work we restrict ourselves to investigate the contribution of the discrete part, in which the photons are mainly produced via the intermediate states $\chi_{cJ}(nP)$. Besides calculating the resonance contributions of $\chi_{cJ}(1P)\; (J=0,1,2)$, we also take into account the contributions of the higher excited states $\chi_{cJ}(2P)$ and the interference effect among the 1P and 2P states. We find that the contribution of the 2P states and the interference terms to the total decay width is very tiny. However, for specific regions of the Dalitz plot, off the resonance peaks, we find that these contributions are sizable and should also be accounted for. We also provide the photon spectrum and study the polarization of $J/\psi$.Comment: 19 pages, 5 figures, minor changes, references added, accepted version in PR

Tokamak burn extension by radial electric field control

This study considers a TFTR-sized plasma operating on a long cycle. The temperature profile is fixed in time, and the plasma is not refuelled. In order to isolate the electric field effects, this last condition is extended to prohibit the electric field at the plasma edge from returning more fuel to the plasma than gradient-driven forces expel

Impact of resonance decays on critical point signals in net-proton fluctuations

The non-monotonic beam energy dependence of the higher cumulants of net-proton fluctuations is a widely studied signature of the conjectured presence of a critical point in the QCD phase diagram. In this work we study the effect of resonance decays on critical fluctuations. We show that resonance effects reduce the signatures of critical fluctuations, but that for reasonable parameter choices critical effects in the net-proton cumulants survive. The relative role of resonance decays has a weak dependence on the order of the cumulants studied with a slightly stronger suppression of critical effects for higher-order cumulants

A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector

We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an assortment of interchangeable radioactive sources could be attached to a weight at the end of the cable. All components exposed to the radiopure liquid scintillator were made of chemically compatible UHV-cleaned materials, primarily stainless steel, in order to avoid contaminating or degrading the scintillator. To prevent radon intrusion, the apparatus was enclosed in a hermetically sealed housing inside a glove box, and both volumes were regularly flushed with purified nitrogen gas. An infrared camera attached to the side of the housing permitted real-time visual monitoring of the cable's motion, and the system was controlled via a graphical user interface.Comment: Revised author affiliations, corrected typos, made minor improvements to text, and revised reference

Search for extraterrestrial antineutrino sources with the KamLAND detector

We present the results of a search for extraterrestrial electron antineutrinos ($\bar{\nu}_{e}$'s) in the energy range $8.3 MeV < E_{\bar{\nu}_{e}} < 31.8 MeV$ using the KamLAND detector. In an exposure of 4.53 kton-year, we identify 25 candidate events. All of the candidate events can be attributed to background, most importantly neutral current atmospheric neutrino interactions, setting an upper limit on the probability of $^{8}$B solar $\nu_{e}$'s converting into $\bar{\nu}_{e}$'s at $5.3 \times 10^{-5}$ (90% C.L.), if we assume an undistorted $\bar{\nu}_{e}$ shape. This limit corresponds to a solar $\bar{\nu}_{e}$ flux of $93 cm^{-2} s^{-1}$ or an event rate of $1.6 events (kton-year)^{-1}$ above the energy threshold $(E_{\bar{\nu}_{e}} > 8.3 MeV)$. The present data also allows us to set more stringent limits on the diffuse supernova neutrino flux and on the annihilation rates for light dark matter particles.Comment: 22 pages, 6 figure

Measurement of the 8B Solar Neutrino Flux with the KamLAND Liquid Scintillator Detector

We report a measurement of the neutrino-electron elastic scattering rate from 8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5 MeV analysis threshold is 1.49+/-0.14(stat)+/-0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a 8B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77+/-0.26(stat)+/-0.32(syst) x 10^6 cm^-2s^-1. The analysis threshold is driven by 208Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic 11Be. The measured rate is consistent with existing measurements and with Standard Solar Model predictions which include matter enhanced neutrino oscillation.Comment: 6 pages, 3 figure

Production of Radioactive Isotopes through Cosmic Muon Spallation in KamLAND

Radioactive isotopes produced through cosmic muon spallation are a background for rare-event detection in $\nu$ detectors, double-$\beta$-decay experiments, and dark-matter searches. Understanding the nature of cosmogenic backgrounds is particularly important for future experiments aiming to determine the pep and CNO solar neutrino fluxes, for which the background is dominated by the spallation production of $^{11}$C. Data from the Kamioka liquid-scintillator antineutrino detector (KamLAND) provides valuable information for better understanding these backgrounds, especially in liquid scintillators, and for checking estimates from current simulations based upon MUSIC, FLUKA, and GEANT4. Using the time correlation between detected muons and neutron captures, the neutron production yield in the KamLAND liquid scintillator is measured to be $(2.8 \pm 0.3) \times 10^{-4} \mu^{-1} g^{-1} cm^{2}$. For other isotopes, the production yield is determined from the observed time correlation related to known isotope lifetimes. We find some yields are inconsistent with extrapolations based on an accelerator muon beam experiment.Comment: 16 pages, 20 figure

The KamLAND Full-Volume Calibration System

We have successfully built and operated a source deployment system for the KamLAND detector. This system was used to position radioactive sources throughout the delicate 1-kton liquid scintillator volume, while meeting stringent material cleanliness, material compatibility, and safety requirements. The calibration data obtained with this device were used to fully characterize detector position and energy reconstruction biases. As a result, the uncertainty in the size of the detector fiducial volume was reduced by a factor of two. Prior to calibration with this system, the fiducial volume was the largest source of systematic uncertainty in measuring the number of anti-neutrinos detected by KamLAND. This paper describes the design, operation and performance of this unique calibration system.Comment: 30 pages, 22 figures, to be submitted to JINS

Precision Measurement of Neutrino Oscillation Parameters with KamLAND

The KamLAND experiment has determined a precise value for the neutrino oscillation parameter $\Delta m^{2}_{21}$ and stringent constraints on $\theta_{12}$. The exposure to nuclear reactor anti-neutrinos is increased almost fourfold over previous results to 2.44$\times10^{32}$ proton-yr due to longer livetime and an enlarged fiducial volume. An undistorted reactor $\bar{\nu}_{e}$ energy spectrum is now rejected at >5$\sigma$. Extending the analysis down to the inverse beta decay energy threshold, and incorporating geo-neutrinos, gives a best-fit at $\Delta m^{2}_{21}$= $7.58^{+0.14}_{-0.13}(stat)^{+0.15}_{-0.15}(syst)\times10^{-5}$ eV$^{2}$ and $\tan^2 \theta_{12}$=$0.56^{+0.10}_{0.07}(stat)^{+0.10}_{-0.06}(syst)$. Local $\Delta \chi^2$-minima at higher and lower $\Delta m^{2}_{21}$ are disfavored at >4$\sigma$. Combining with solar neutrino data, we obtain $\Delta m^{2}_{21}$= $7.59^{+0.21}_{-0.21}\times10^{-5}$ eV$^{2}$ and $\tan^2 \theta_{12}$=$0.47^{+0.06}_{-0.05}$.Comment: Version as published in PRL. Revised Fig. 2 (allowed contours) due to an error in the figure generating code (numbers or conclusions did not change). The full dChi2-map for this analysis is available at http://www.awa.tohoku.ac.jp/KamLAND/chi2map_3rdresult/chi2map.html . Fig. 3 (low E spectrum) was dropped due to space limitation