Search

A search of neutrino magnetic moments 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 $\cpd$ near threshold were achieved. Details of the reactor neutrino source, experimental hardware, background understanding and analysis methods are presented. Based on 570.7 and 127.8 days of Reactor ON and OFF data, respectively, at an average Reactor ON electron anti-neutrino flux of $\rm{6.4 \times 10^{12} cm^{-2} s^{-1}}$, the limit on the neutrino magnetic moments of $\rm{\munuebar < 7.4 \times 10^{-11} \mub}$ at 90% confidence level was derived. Indirect bounds on the $\nuebar$ radiative decay lifetimes were inferred., 16 pages, 15 figures, 9 tables

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 $1\text{ }\mathrm{k}{\mathrm{g}}^{\mathrm{\ensuremath{-}}\mathrm{1}}\text{ }\mathrm{k}\mathrm{e}{\mathrm{V}}^{\mathrm{\ensuremath{-}}\mathrm{1}}\text{ }\mathrm{d}\mathrm{a}{\mathrm{y}}^{\mathrm{\ensuremath{-}}\mathrm{1}}$ 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 ${\ensuremath{\mu}}_{{\overline{\ensuremath{\nu}}}_{e}}l1.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}{\ensuremath{\mu}}_{\mathrm{B}}$ at $90%$ confidence level was derived. An indirect bound of the ${\overline{\ensuremath{\nu}}}_{e}$ radiative lifetime of ${m}_{\ensuremath{\nu}}^{3}{\ensuremath{\tau}}_{\ensuremath{\nu}}g2.8\ifmmode\times\else\texttimes\fi{}{10}^{18}\text{ }\mathrm{e}{\mathrm{V}}^{\mathrm{3}}\text{ }\mathrm{s}$ can be inferred.

The photofission cross section of $^{232}\mathrm{Th}$ was measured in the 5.8--12 MeV energy range with an average photon energy resolution of 600 eV. Intermediate structure was observed at 5.91, 5.97, and 6.31 MeV. The experimental fission probability and various properties of the intermediate structure were compared with calculated values based on a double-humped fission barrier as well as a triple-humped one. The results favor, though not decisively, the presence of a shallow third well in the barrier. Certain features of both barriers, a rather high first hump and a deep secondary well, are quite different from those predicted by current theoretical barrier calculations.

The simultaneous formation of the two deuterium plasma foci has been reported recently by Hou et al. in a Mather type two-gun plasma focus assembly with maximum bank energy of ∼700 kJ. In addition, these plasmas will evolve and then produce a disk-shaped plasma in the middle of the two plasma foci. Soft X-ray filter techniques which allow measurements of the electron temperature at both pinch points and the middle point yielded a few hundred eV for these three regions. Neutron localization measurements which were carried out with a collimator and a scintillator-fiber-photomultiplier assembly indicate that an enhancement of ∼80% in neutron yield is observed in the middle region as the separation between two electrodes is 9.1cm. Further experimental evidence shows that the neutron production in the middle region is the result of the beam-beam interaction in nature.

High intensity proton beams from the Dynamitron at Brooklyn College are used to generate monochromatic gamma rays from known (p, r) resonances in various nuclei. The gamma rays, whose energy varies continuously as a function of the angle with the proton beam, are used in turn to measure photofission cross sections in 238U and 232Th. The number of suitable (p, r) resonances is sufficient to cover the 5 - 13 MeV range of excitation energy with an average step of ~ 100 keV. For a resonance of average strength the yield is 103 photons per ?A of protons on target. The energy spread is typically 20 - 40 keV and a gamma ray energy resolution of 200 eV can easily be reached. This resolution is adequate for investigating structure in the photofission cross sections resulting from class II states in the second well of the fission barrier.