Review of Methods of Power-Spectrum Analysis as Applied to Super-Kamiokande Solar Neutrino Data

To help understand why different published analyses of the Super-Kamiokande solar neutrino data arrive at different conclusions, we have applied six different methods to a standardized problem. The key difference between the various methods rests in the amount of information that each processes. A Lomb-Scargle analysis that uses the mid times of the time bins and ignores experimental error estimates uses the least information. A likelihood analysis that uses the start times, end times, and mean live times, and takes account of the experimental error estimates, makes the greatest use of the available information. We carry out power-spectrum analyses of the Super-Kamiokande 5-day solar neutrino data, using each method in turn, for a standard search band (0 to 50 yr-1). For each method, we also carry out a fixed number (10,000) of Monte-Carlo simulations for the purpose of estimating the significance of the leading peak in each power spectrum. We find that, with one exception, the results of these calculations are compatible with those of previously published analyses. (We are unable to replicate Koshio's recent results.) We find that the significance of the peaks at 9.43 yr-1 and at 43.72 yr-1 increases progressively as one incorporates more information into the analysis procedure.Comment: 21 pages, 25 figure

Supernova burst and relic neutrino sensitivity studies in the Hyper-Kamiokande Korean sites

Hyper-Kamiokande is a next-generation water Cherencov detector for neutrino physics. Its large volume (260 kton × 2) allows Supernova burst (SN) neutrino and Supernova Relic Neutrino (SRN) search much more promising than current Super-Kamiokande detector (50 kton). With an alternative plan of locating one of the two identical detectors to Korea, better physics sensitivities are expected because of less muon flux and its spallation isotopes due to more overburden in Korean candidate sites than Japanese Hyper-Kamiokande site (Tochibora). According to our study using simple MC 102 SRN events (5.2 sigma) in a Korean site and 71 SRN events (4.2 sigma) in the Japanese site are expected for 10 years of operation for one detector. Sensitivity studies using a full MC will be performed in the near future

Effects of organic plant oils and role of oxidation on nutrient utilization in juvenile rainbow trout (Oncorhynchus mykiss)

The study compared the effect of four either fresh or force oxidized organic plant oils in diets for juvenile rainbow trout (Oncorhynchus mykiss) in which 47% of conventional LT fish meal protein was substituted by a mixture of 3 organic plant protein concentrates. Fish oil was completely substituted with either organic linseed oil; rape seed oil; sunflower oil or grape seed oil and evaluated based on feed intake, feed utilization, growth and digestibility. None of the plant oils affected feed intake and growth parameters. Organic plant oils had all a positive effect on lipid digestibility as compared with the fish oil based control diet, despite the very different FA profiles. The organic vegetable oils did not undergo autoxidation, as opposed to the fish oil control for which lipid digestibility was significantly negative influenced

Influence of Soya Oil Blended with Fish Oil on Growth Performance and Lipid Profile of Red Sea Bream Pagrus major

Continuous increase in fish feed prices due to deterioration of fish oil sources and quality catalyzes intensive research efforts to study alternatives for dietary fish oil such as soya oil.  Being rich in linolenic acid (C18:2n-6), soya oil has a competitive edge as an arachidonic acid (ARA) precursor. A 50-day feeding trial was conducted to evaluate the effects of dietary soya oil as a substitute for fish oil on growth performance and lipid composition of juvenile red seabream, Pagrus major.  Four types of iso-nitrogenous experimental diets formulated in this feeding trial consisted of 100% fish oil (10F), 80% fish oil and 20% soya oil (8F2S), 60% fish oil and 40% soya oil (6F4S), and finally, 40% fish oil and 60% soya oil (4F6S). All diets were fed to triplicate groups of 15 red seabream with an initial mean weight of 4.9 ± 0.1 g twice daily to apparent satiation. Our results demonstrated that inclusion of soya oil as a lipid source to partially replace fish oil in red seabream diet led to the highest body weight gain (BWG) in 10F (837.2 ± 2.2%), followed by 8F2S (786.9 ± 38.3%), 6F4S (764.6 ± 5.2%) and 4F6S (682.0 ± 17.2%), respectively, without any significant differences among 10F, 8F2S and 6F4S. Soya oil inclusion also gradually decreased BWG and specific growth rate (SGR); both BWG and SGR in 4F6S were significantly lower than other treatments. Feed conversion ratio (FCR) and feed intake (FI) showed no significant differences among treatments. Survival rate of all treatments exceeded 90% although the hepatosomatic index (HSI) in 4F6S was significantly higher than other treatments and serum glutamic-oxaloacetic transaminase (GOT) increased gradually with a higher inclusion of soya oil. Lipid deposition in the whole body was the highest in fish fed with dietary 10F and decreased in relation to the elevated concentration of soya oil in diets. The ventral muscles had doubled the amount of lipid deposition as compared to dorsal muscles. Dominance of saturates among total fatty acid composition particularly C16:0, was similarly observed in the dorsal and ventral muscles as well as the liver. Saturates, monoenes, n-3 and ratio of n-3/n-6 observed have a similar gradient degradation in the dorsal and ventral muscles and the liver. An inverse relationship of inclusion level of soya oil on eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) in both dorsal and ventral muscles including the liver was also observed. In conclusion, diets not exceeding 40% soya oil are suitable as fish oil replacement in the diet of juvenile red seabream without significantly affecting the overall growth performance of this fish. Keywords: Pagrus major, red seabream, soya oil, growth performances, lipid profile ABSTRAK Kenaikan harga makanan ikan yang berterusan akibat kekurangan sumber dan juga kualiti minyak ikan, telah menggalakkan lebih banyak penyelidikan untuk mengkaji minyak soya sebagai sumber alternatif kepada minyak ikan. Kekayaan sumber asid linolenik (C18:2n-6) telah menjadikan minyak soya sebagai pelopor kepada asid arakidonik (ARA). Satu kajian pemakanan selama 50 hari telah dijalankan untuk menilai kesan pemakanan dengan menggunakan minyak soya ke atas tumbesaran dan komposisi lemak dalam ikan merah, Pagrus major juvenil. Empat jenis diet kajian iso-nitrogenus telah diformulasikan dalam kajian ini; yang terdiri daripada 100% minyak ikan (10F), 80% minyak ikan dan 20% minyak soya (8F2S), 60% minyak ikan dan 40% minyak soya (6F4S), dan 40% minyak ikan dan 60% minyak soya (4F6S). Semua diet telah diberikan dua kali sehari sehingga kenyang kepada sejumlah 15 ekor ikan merah dengan purata berat awal 4.9 + 0.1 g secara triplikat. Keputusan menunjukkan bahawa penggunaan minyak soya sebagai sumber lemak untuk menggantikan sebahagian sumber minyak ikan dalam ikan merah telah memberikan BWG dalam perlakuan 10F (837.2 + 2.2%), diikuti dengan 8F2S (786.9 + 38.3%), 6F4S (764.6 + 5.2%) dan 4F6S (682.0 + 17.2%), masing-masing, tanpa perbezaan yang bererti di antara perlakuan 10F, 8F2S and 6F4S. Penggunaan minyak soya juga mengurangkan BWG dan SGR secara perlahan-lahan; kedua-dua BWG and SGR dalam perlakuan 4F6S menunjukkan nilai rendah yang bererti berbanding perlakuan yang lain. Nisbah penukaran makanan (FCR) dan kadar pengambilan makanan (FI) telah menunjukkan tiada perbezaan yang bererti di antara semua perlakuan. Kadar kemandirian untuk semua perlakuan adalah melebihi 90% walaupun indeks hepatosomatik (HSI) dalam perlakuan 4F6S adalah lebih tinggi secara bererti berbanding perlakuan yang lain, dan serum glutamik-oksaloasetik transaminase (GOT) pula berkurangan dengan penambahan minyak soya. Pengumpulan lemak di keseluruhan tubuh adalah tertinggi dalam ikan yang diberi makanan 10F dan berkurangan dengan penambahan kepekatan minyak soya dalam diet. Kandungan lemak pada otot ventral juga telah meningkat sebanyak dua kali ganda berbanding dengan pada otot dorsal. Kandungan saturat dari jumlah komposisi asid lemak terutamanya C16:0 adalah lebih dominan pada otot dorsal, otot ventral dan hati. Saturat, monoene, n-3 dan nisbah n-3/n-6 telah menunjukkan kecerunan degradasi yang sama pada otot dorsal, otot ventral dan hati. Peningkatan minyak soya menyebabkan kesan songsang terhadap aras asid eikosapentanoik (EPA) and asid dokosaheksanoik (DHA) di kedua-dua otot dorsal dan ventral dan juga hati. Sebagai kesimpulan, diet yang mengandungi minyak soya tidak melebihi 40% adalah paling sesuai sebagai pengganti minyak ikan tanpa memberi kesan yang bererti kepada tumbesaran ikan merah juvenil. Kata kunci: Pagrus major, ikan merah, minyak soya, tumbesaran, profil lipid

Distillation of Liquid Xenon to Remove Krypton

A high performance distillation system to remove krypton from xenon was constructed, and a purity level of Kr/Xe = $\sim 3 \times 10^{-12}$ was achieved. This development is crucial in facilitating high sensitivity low background experiments such as the search for dark matter in the universe.Comment: 15 pages, 11 figure

Scintillation-only Based Pulse Shape Discrimination for Nuclear and Electron Recoils in Liquid Xenon

In a dedicated test setup at the Kamioka Observatory we studied pulse shape discrimination (PSD) in liquid xenon (LXe) for dark matter searches. PSD in LXe was based on the observation that scintillation light from electron events was emitted over a longer period of time than that of nuclear recoil events, and our method used a simple ratio of early to total scintillation light emission in a single scintillation event. Requiring an efficiency of 50% for nuclear recoil retention we reduced the electron background to 7.7\pm1.1(stat)\pm1.2 0.6(sys)\times10-2 at energies between 4.8 and 7.2 keVee and to 7.7\pm2.8(stat)\pm2.5 2.8(sys)\times10-3 at energies between 9.6 and 12 keVee for a scintillation light yield of 20.9 p.e./keV. Further study was done by masking some of that light to reduce this yield to 4.6 p.e./keV, the same method results in an electron event reduction of 2.4\pm0.2(stat)\pm0.3 0.2(sys)\times10-1 for the lower of the energy regions above. We also observe that in contrast to nuclear recoils the fluctuations in our early to total ratio for electron events are larger than expected from statistical fluctuations.Comment: 25 pages, 15 figure

Indications of Neutrino Oscillation in a 250 km Long-baseline Experiment

The K2K experiment observes indications of neutrino oscillation: a reduction of $\nu_\mu$ flux together with a distortion of the energy spectrum. Fifty-six beam neutrino events are observed in Super-Kamiokande (SK), 250 km from the neutrino production point, with an expectation of $80.1^{+6.2}_{-5.4}$. Twenty-nine one ring $\mu$-like events are used to reconstruct the neutrino energy spectrum, which is better matched to the expected spectrum with neutrino oscillation than without. The probability that the observed flux at SK is explained by statistical fluctuation without neutrino oscillation is less than 1%.Comment: 5 pages, 3 figures embedded, LaTeX with RevTeX style, accepted for publication in PRL on December 13, 200

Self-shielding effect of a single phase liquid xenon detector for direct dark matter search

Liquid xenon is a suitable material for a dark matter search. For future large scale experiments, single phase detectors are attractive due to their simple configuration and scalability. However, in order to reduce backgrounds, they need to fully rely on liquid xenon's self-shielding property. A prototype detector was developed at Kamioka Observatory to establish vertex and energy reconstruction methods and to demonstrate the self-shielding power against gamma rays from outside of the detector. Sufficient self-shielding power for future experiments was obtained.Comment: 8 pages, 8 figure

Constraints on neutrino oscillation parameters from the measurement of day-night solar neutrino fluxes at Super-Kamiokande

A search for day-night variations in the solar neutrino flux resulting from neutrino oscillations has been carried out using the 504 day sample of solar neutrino data obtained at Super-Kamiokande. The absence of a significant day-night variation has set an absolute flux independent exclusion region in the two neutrino oscillation parameter space.Comment: 11 pages, 3 figures, submitted to PRL, single-spacin