Y Liu

Limit on the Electron Neutrino Magnetic Moment from the Kuo-Sheng Reactor Neutrino Experiment

A search of neutrino magnetic moment was carried out at the Kuo-Sheng Nuclear Power Station at a distance of 28 m from the 2.9 GW reactor core. With a high purity germanium detector of mass 1.06 kg surrounded by scintillating NaI(Tl) and CsI(Tl) crystals as anti-Compton detectors, a detection threshold of 5 keV and a background level of 1 kg(-1) keV(-1) day(-1) at 12-60 keV were achieved. Based on 4712 and 1250 h of reactor ON and OFF data, respectively, the limit on the neutrino magnetic moment of mu(nu;(e))<1.3x10(-10)mu(B) at 90% confidence level was derived. An indirect bound of the nu;(e) radiative lifetime of m(3)(nu)tau(nu)>2.8x10(18) eV(3) s can be inferred.

Measurement of Nu(e)-bar -Electron Scattering Cross-Section with a CsI(Tl) Scintillating Crystal Array at the Kuo-Sheng Nuclear Power Reactor

The {nu}{sub e}-e{sup -} elastic scattering cross section was measured with a CsI(Tl) scintillating crystal array having a total mass of 187 kg. The detector was exposed to an average reactor {nu}{sub e} flux of 6.4x10{sup 12} cm{sup -2} s{sup -1} at the Kuo-Sheng Nuclear Power Station. The experimental design, conceptual merits, detector hardware, data analysis, and background understanding of the experiment are presented. Using 29882/7369 kg-days of Reactor ON/OFF data, the standard model (SM) electroweak interaction was probed at the squared 4-momentum transfer range of Q{sup 2{approx}}3x10{sup -6} GeV{sup 2}. The ratio of experimental to SM cross sections of {xi}=[1.08{+-}0.21(stat){+-}0.16(sys)] was measured. Constraints on the electroweak parameters (g{sub V},g{sub A}) were placed, corresponding to a weak mixing angle measurement of sin{sup 2{theta}}{sub W}=0.251{+-}0.031(stat){+-}0.024(sys). Destructive interference in the SM {nu}{sub e}-e process was verified. Bounds on anomalous neutrino electromagnetic properties were placed: neutrino magnetic moment at {mu}{sub {nu}{sub e}} <3.3x10{sup -32} cm{sup 2}, both at 90% confidence level.

A CsI(Tl) scintillating crystal detector for the studies of low-energy neutrino interactions

Abstract Scintillating crystal detector may offer some potential advantages in the low-energy, low-background experiments. A 500 kg CsI(Tl) detector to be placed near the core of Kuo-sheng Nuclear Power Station in Taiwan is being constructed for the studies of electron–neutrino scatterings and other keV–MeV range neutrino interactions. The motivations of this detector approach, the physics to be addressed, the basic experimental design, and the characteristic performance of prototype modules are described. The expected background channels and their experimental handles are discussed.Scintillating crystal detector may offer some potential advantages in the low-energy, low-background experiments. A 500 kg CsI(Tl) detector to be placed near the core of Nuclear Power Station II in Taiwan is being constructed for the studies of electron-neutrino scatterings and other keV−MeV range neutrino interactions. The motivations of this detector approach, the physics to be addressed, the basic experimental design, and the characteristic performance of prototype modules are described. The expected background channels and their experimental handles are discussed. PACS Codes: 14.60.Pq; 29.40.Mc

Studies of prototype CsI(Tl) crystal scintillators for low-energy neutrino experiments

Crystal scintillators provide potential merits for the pursuit of low-energy low-background experiments. A CsI(Tl) scintillating crystal detector is being constructed to study low-energy neutrino physics at a nuclear reactor, while projects are underway to adopt this technique For Dark Matter searches. The choice of the geometrical parameters of the crystal modules. as well as the optimization of the readout scheme, are the results of an R&D program. Crystals 40 cm in length were developed. The detector requirements and the achieved performance of the prototypes are presented. Future prospects for this technique are discussed

The Electronics and Data Acquisition Systems of a CsI(Tl) Scintillating Crystal Detector for Low Energy Neutrino Experiment

Be solar neutrinos and other topics. The merits of scintillating crystal detector inlow-energy low-background experiment were recently discussed [2]. An experiment witha CsI(Tl) detector placed near a reactor core to study neutrino interactions at low energyis being constructed [3]. In the first data-taking phase, the detector is based on 200 kg ofCsI(Tl) scintillating crystals

Prospects of scintillating crystal detector in low-energy low-background experiments

A scintillating crystal detector offers potential advantages in low-energy (keV-MeV range) low-background experiments for particle physics and astrophysics. The merits are discussed using CsI(T1) crystal as illustrations. The various physics topics, which can be pursued with this detector technology, are summarized. A conceptual design for a generic detector is presented

Nuclear recoil measurement in CsI(Tl) crystal for Cold Dark Matter detection

The potential merits of CsI(TI) scintillating crystals for Dark Matter experiments make it a subject of recent interest. The scattering signatures by neutrons on a CsI(Tl) detector were studied using a neutron beam generated by a 13 MV Tandem accelerator. The energy spectra of nuclear recoils from 7 keV to 132 keV were measured, and their quenching factors for scintillating light yield were derived. The data represents the first confirmation of the Optical Model predictions on neutron elastic scatterings with a direct measurement on the nuclear recoils of heavy nuclei

Near threshold pulse shape discrimination techniques in scintillating CsI(Tl) crystals

There are recent interests with CsI(T1) scintillating crystals for Dark Matter experiments. The key merit is the capability to differentiate nuclear recoil (nr) signatures from the background beta/gamma-events due to ambient radioactivity on the basis of their different pulse shapes. One of the major experimental challenges is to perform such pulse shape analysis in the statistics-limited domain where the light output is close to the detection threshold. Using data derived from measurements with low-energy gammas and nuclear recoils due to neutron elastic scatterings, it was verified that the pulse shapes between beta/gamma-events are different. Several methods of pulse shape discrimination (PSD) are studied, and their relative merits are compared. Full digitization of the pulse shapes is crucial to achieve good discrimination. Advanced software techniques with mean time, neural network and likelihood ratios give rise to satisfactory performance, and are superior to the conventional Double Charge method commonly applied at higher energies. PSD becomes effective starting at a light yield of about 20 photo-electrons. This corresponds to a detection threshold of about 5 keV electron-equivalence energy, or 40-50 keV recoil kinetic energy, in realistic experiments