Measurement of gamow-teller strength for 176Yb --> 176Lu and the efficiency of a solar neutrino detector

We report a 0 degrees 176Yb(p,n)176Lu measurement at IUCF where we used 120 and 160 MeV protons and the energy dependence method to determine Gamow-Teller (GT) matrix elements relative to the model independent Fermi matrix element. The data show that there is an isolated concentration of GT strength in the low-lying 1(+) states making the proposed Low Energy Neutrino Spectroscopy detector (based on neutrino captures on 176Yb) sensitive to pp and 7Be neutrinos and a promising detector to resolve the solar neutrino problem.     

Nuclear responses for neutrinos and neutrino studies by double beta decays and inverse beta decays

This is a brief report on recent studies of nuclear responses for neutrinos (v) by charge exchange reactions, v masses by double beta (ββ) decays and of solar and supernova v’s by inverse β decays. Subjects discussed include (1) v studies in nuclear micro-laboratories, (2) v masses studied by ββ decays of ¹⁰⁰Mo and nuclear responses for ββ — v, (3) solar and supernova v’s by inverse β decays and v responses for ⁷¹Ga and ¹⁰⁰Mo, and (4) MOON (molybdenum observatory of neutrinos) for spectroscopic studies of Majorana v masses with sensitivity of m _v ∼ 0.03 eV by ββ decays of ¹⁰⁰Mo and real-time studies of low energy solar and supernova v’s by inverse β decays of ¹⁰⁰Mo.     

The proton-proton reaction,solar neutrinos,and a relativistic field theoretic model of the deuteron

In a series of recent papers, Ivanov et al. and Oberhummer et al. have calculated the rate for the p + p → d + e⁺ + ν_e reaction with a zero-range four-fermion effective interaction and find a result 2.9 times higher than the standard value calculated from non-relativistic potential theory. Their procedure is shown to give a wrong answer because their assumed interaction disagrees with low-energy pp scattering data.     

Feasibility of detection of solar neutrinos and other astrophysical particles using superconducting filaments

Neutrinos from the sun or from a supernova will scatter coherently from target nuclei, and the associated nuclear recoil energy could in principle be detected using the significant local temperature rise produced at low temperatures in materials with a negligible electronic specific heat. Heavy ‘dark matter’ particles such as photinos might also be detected in this way. Drukier and Stodolsky [7] have suggested the use of a target in the form of superheated grains of superconductor which would be switched to the resistive state by individual neutrino scattering events, producing small but detectable local magnetic flux changes. The present paper considers the alternative scheme of a target consisting of coils of fine single or multi-filament superconducting wires, allowing the local resistive transitions to be detected as voltage pulses at the coil input. Calculations are presented of neutrino event rate versus energy deposited as a function of the target (A, Z) value, and the required filament diameter as a function of temperature and recoil energy, taking into account the latent heat requirements of the superconductor at transition. The possibility of using electrically parallel arrays of filaments is analysed, and the magnitude of the external voltage pulse is estimated for a range of type 1 and type 2 superconducting materials, including the effect of propagation of the normal zone. It is concluded that measurable voltage signals could in general be obtained with both type 1 and type 2 superconductors, and for operating temperatures in the region 10–100 mK typical filament diameters would range from 10–40 micron (for 30 eV recoil energy sensitivity) 40–160 micron (for 3 keV recoil energy sensitivity).     

Investigation of hyperfine structure and isotope shift of the 605.5 nm-line of Lu176 by laser spectroscopy

Using a tunable single mode dye laser the hyperfine structure of the transition 5d6s ^{2 2} D _5/2 — 5d6s6p ⁴ F _5/2 has been investigated for the Lu-isotopes Lu¹⁷⁵ and Lu¹⁷⁶. From our measurements the following values for the hyperfine constantsA andB could be deduced Lu¹⁷⁶ 5d6s6p ⁴ F _5/2:A=698.4 (0.4) MHz,B=1,564 (10) MHz 5d6s ^{2 2} D _5/2:A=104.1 (0.3) MHz.B=2,631 (6) MHz Lu¹⁷⁵ 5d6s6p ⁴ F ^5/2:A=987.2(0.4) MHz,B=1,117(6) MHz. The isotope shift between the line centers has been determined to be IS(176-175, 605.5 nm)=?420(10) MHz.     

Higgs charged bosons and the problem of solar neutrinos

For a model with the SU(2)L×SU(2)_R×U(1)_{B−L} gauge group, the passage of neutrino flux through a substance is studied. It is shown that Higgs charged physical bosons can considerably change the potential of neutrino interaction with the solar substance. An analytical expression for the survival probability of left-handed electron neutrinos is derived in the two-flavor approximation. Yanka Kupala Grodno State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 32–37, January, 2000.     

On the question of the magnitude of day-night asymmetry for solar neutrinos

The effect of flavor day-night asymmetry is considered for solar neutrinos of energy about 1 MeV under the assumption that the electron-density distribution within the Earth is approximately piecewise continuous on the scale of the neutrino-oscillation length. In this approximation, the resulting asymmetry factor for beryllium neutrinos does not depend on the structure of the inner Earth’s layers or on the properties of the detector used. Its numerical estimate is on the order of ?4 × 10^?4, which is far beyond the reach of present-day experiments.     

Method for recording of solar neutrinos with a lithium detector

A method for solar neutrino recording on a laboratory bench with a lithium detector is developed. The efficiency of extraction of beryllium from lithium as high as 96.4% is achieved, and it is shown that lithium extraction losses are less than 1%. The results of a full-scale experiment with a 10-t lithium detector consisting of 20 500-kg modules are presented. Technical solutions based on the experimental results open the way to designing a pilot facility intended for 500 kg of lithium.     

Hard gamma radiation in the decay of Lu176m

Gamma lines 1·05 MeV(4 × 10^–6 quanta/decay) and 1·14 MeV (9 × 10^–6 quanta/decay), giving evidence of the existence of a new level in Hf¹⁷⁶ with an energy of 1·14 MeV, were found in the decay of Lu^176m with a half-life of 3·7 hours, using the scintillation method. The component of the beta spectrum, exciting this level, has a maximum energy of 0·17 MeV and logft=8·3. The spin of this level proved to be equal to one. The level was interpreted as a single-particle neutron level withn ₀: 5/2^– (512),n ₁: 7/2^– (514);I=1⁺.

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- Lu^176m

Lu^176m 3,7 - 1,05 MeV (4.10^–6 /) 1,14 MeV (9.10^–6 / /), Hf¹⁷⁶ 1,14 MeV. -, , 0,17 MeV logft = =8,3. . cn ₀: 5/2^– (512),n ₁: 7/2^– (514);I = 1⁺h

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The authors thank L. K. Peker from the Leningrad State University for a helpful discussion of their results.     

Oscillator strengths for SiH and SiH deduced from the solar spectrum

Recent identifications of SiH (A²Δ-X²Π) and SiH⁺ (A¹Π-X¹Σ⁺) in the solar photospheric spectrum have enabled us to derive absolute oscillator strengths for the (0, 0) bands of these transitions: f₀₀(SiH) = 0.0033 and f₀₀(SiH⁺) = 0.0005. Our result for SiH is compared with other values.     

Oscillations of three generations of neutrinos and the solar neutrino problem

The resonant neutrino oscillations in matter are assumed to be responsible for the observed reduction in the capture rate for the ³⁷Cl detector. The expression of the probability that a solar v_e reaches the Earth as a v_e is given in the case of three generations. In the small mixing angle approximation, we describe all the regions of neutrino parameters which give rise to a capture rate of 2.1 SNU for ³⁷Cl and we give the corresponding prediction for the ⁷¹Ga detector.     

Search for cold dark matter and solar neutrinos with GENIUS and GENIUS-TF

The new project GENIUS will cover a wide range of the parameter space of predictions of supersymmetry for neutralinos as cold dark matter. Further, it has the potential to be a real-time detector for low-energy (pp and ⁷Be) solar neutrinos. The GENIUS Test Facility has just been funded and will come into operation by the end of 2001.     

Solar neutrinos, the presolar abundance of helium and the solar metallicity

Summary The observational estimates of the presolar abundance of helium (Y _s) are reviewed and a lower value ofY _s ({-0.19 by mass fraction) is suggested to solve the solar-neutrino problem. With this reduced value ofY _s it is argued from the point of view of maintaining the luminosity of the Sun at its observed level that the metallicity requirement isZ _s{-0.013. Previous workers, while considering lowerY _s in the range of 0.15÷0.20, have assumedZ _s in the range of either 0.018÷0.020 or 0.001÷0.004. We suggest that forY _s=0.15÷0.20, one should rather considerZ _s=0.01÷0.02 in order to obtain a global solution that explains the observed modes of solar oscillation as well as the observed neutrino flux. This solution is quite interesting as we find that the real uncertainties in the determination of the solar metallicity arising from the diversity in existing models of the solar atmosphere suggestZ _s{-{0.018±0.005.

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Riassunto Si esaminano le stime di osservazione dell'abbondanza presolare di elio (Y _s) e si sugge risce un valore diY _s inferiore ({-0.19 in posizione di massa) per risolvere il problema dei neutrini solari. Con questo valore ridotto diY _s si deduce dal punto di vista di mantenere la luminosità del Sole al livello osservato che il requisito di metallicità èZ _s=0.013. Alcuni ricercatori in precedenza, considerando unY _s inferiore, nell'intervallo 0.15÷0.20, hanno ipotizzato cheZ _s si trovi nell'intervallo 0.018÷0.020 o 0.001÷0.004. Si suggerisce che perY _s=0.15÷0.20, si dovrebbe piuttosto considerareZ _s=0.01÷0.02 per ottenere una soluzione globale che spieghi i modi osservati di oscillazione solare cosí come il flusso di neutrini osservato. Questa soluzione è piuttosto interessante poiché si trova che le incertezze reali nella determinazione della metallicità solare che derivano dalla diversità in modelli esistenti dell'atmosfera solare suggeriscono cheZ _s{-0.018±0.005.

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Резюме Предлагается обзор оценок распространенности гелия на солнце (Y _s). Предполагается, что низшая величинаY _s ({-0.19 массовой доли) решает проблему солнечных нейтрино. Эта величинаY _s приводит к требованию металлических свойствZ _s{-0.013. В предыдущих работах, где рассматривалась меньшая величинаY _s в области 0.15÷0.020, предполагалось, чтоZ _s находится либо в области 0.018÷0.020, либо в области 0.001÷0.004. Мы предполагаем, что дляY _s=0.15÷0.20 следует принятьZ _s в областиZ _s=0.01÷0.02, чтобы получить глобальное решение, которое объясняет наблюдаемые моды солнечных осцилляций и наблюдаемый поток нейтрино. Это решение представляет интерес, т.к. мы получаем, что реальные неопределенности при определении металлических свойств солннца, обусловленные разбросом существующих модей солнечной атмосферы, предлагают, чтоZ _s{-0.18±0.005.

     

Oscillator strengths for the resonance transition in Fe15+

Summary We report Hartree-Fock and configuration-interaction calculations of both the length and velocity forms of the oscillator strengths for the resonance excitation 1s ²2s ² p ⁶3s ² S _J ^e →1s ²2s ²2p ⁵3s ^{2 2} P _J ⁰ , transition, which leads to autoionization (Auger transition), in the Fe¹⁵⁺ ion of the sodium isoelectronic sequence both inLS and intermediate coupling schemes. Comparison is made with available results. A part of this work was done while the author was Research Director and Professor, CNRS Laboratory, University of Paris-Sud, Paris and Observatoire de Paris, Meudon, Paris, France.     

The Sudbury Neutrino Observatory: Observation of flavor change for solar neutrinos

The Sudbury Neutrino Observatory (SNO) experiment was constructed by an international scientific collaboration primarily to provide a clear determination of whether solar neutrinos change their flavor in transit from the core of the sun to the earth. The detector used 1000 tonnes of heavy water (>99.92% D2O) in an ultra‐clean location 2 km underground in INCO's Creighton mine near Sudbury, Canada to observe two separate reactions of neutrinos on deuterium. The first reaction was sensitive only to electron flavor neutrinos and the second reaction was equally sensitive to all neutrino flavors. The measurements by SNO showed clearly that the hypothesis of no neutrino flavor change was ruled out by more than 5.3 standard deviations. The observation of flavor change for neutrinos implies that they have a non‐zero mass. The measured total flux of active neutrinos from ⁸B decay in the sun was found to be in excellent agreement with the predictions of solar model calculations. This paper describes the history and scientific measurements of the SNO experiment. 2     

On the possibilities for studying the electromagnetic properties of monoenergetic solar neutrinos in the borexino experiments

Electroweak (EW) and electromagnetic (EM) scattering of solar beryllium neutrinos by electrons are analyzed. An analysis of the influence of the mean-square charge radius of an electron neutrino $ r_{\nu _e } = \sqrt {\left\langle {r_{_{\nu _e } }^2 } \right\rangle } $ r_{\nu _e } = \sqrt {\left\langle {r_{_{\nu _e } }^2 } \right\rangle } on differential and total cross sections is performed. The possibility of measuring the magnetic moment of an electron neutrino (μ_v) on the basis of isolating its contribution to the section of the discussed processes is considered.