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On the mass eigenstate purity of Boron-8 solar neutrinos

Description: We give a brief report on our recent paper, Ref. [1], in which we calculate the {nu}{sub 2} mass eigenstate purity of {sup 8}B solar neutrinos as 91 {+-} 2%.
Date: January 1, 2006
Creator: Parke, Stephen J.; /Fermilab; Nunokawa, Hiroshi; /Rio de Janeiro, Pont. U. Catol.; Zukanovich Funchal, Renata & U., /Sao Paulo
Partner: UNT Libraries Government Documents Department

Reactions of halo states: Coulomb excitations

Description: Coulomb dissociation is a relatively clean probe of the structures of one- and two-nucleon halo nuclei. This is illustrated by the breakup of {sup 11}Be, {sup 8}B and {sup 11}Li and is discussed in terms of first order perturbation theory. First-order dipole transitions usually dominate the Coulomb dissociation but quadrupole transitions are not insignificant for a proton halo (e.g. {sup 8}B). Higher-order processes can also distort the observables, such as the momentum distributions of the fragments and the excitation energy spectrum.
Date: September 1, 1997
Creator: Esbensen, H.
Partner: UNT Libraries Government Documents Department

Tandem Terminal Ion Source

Description: OAK-B135 Tandem Terminal Ion Source. The terminal ion source (TIS) was used in several experiments during this reporting period, all for the {sup 7}Be({gamma}){sup 8}B experiment. Most of the runs used {sup 1}H{sup +} at terminal voltages from 0.3 MV to 1.5 MV. One of the runs used {sup 2}H{sup +} at terminal voltage of 1.4 MV. The other run used {sup 4}He{sup +} at a terminal voltage of 1.37 MV. The list of experiments run with the TIS to date is given in table 1 below. The tank was opened four times for unscheduled source repairs. On one occasion the tank was opened to replace the einzel lens power supply which had failed. The 10 kV unit was replaced with a 15 kV unit. The second time the tank was opened to repair the extractor supply which was damaged by a tank spark. On the next occasion the tank was opened to replace a source canal which had sputtered away. Finally, the tank was opened to replace the discharge bottle which had been coated with aluminum sputtered from the exit canal.
Date: October 23, 2000
Partner: UNT Libraries Government Documents Department

{sup 7}Be(p, {gamma}){sup 8}B and the high-energy solar neutrino flux

Description: Despite thirty years of extensive experimental and theoretical work, the predicted solar neutrino flux is still in sharp disagreement with measurements. The solar neutrino measurements strongly suggest that the problem cannot be solved within the standard electroweak and astrophysical theories. Thus, the solar neutrino problem constitutes the strongest evidence for physics beyond the Standard Model. Whatever the solution of the solar neutrino problem turns out to be, it is of paramount importance that the input parameters of the underlying electroweak and solar theories rest upon solid ground. The most uncertain nuclear input parameter in standard solar models is the low-energy {sup 7}Be(p, {gamma}){sup 8}B radiative capture cross section. This reaction produces {sup 8}B in the Sun, whose {beta}{sup +} decay is the main source of the high-energy solar neutrinos. Here, the importance of the {sup 7}Be(p, {gamma}){sup 8}B reaction in predicting the high energy solar neutrino flux is discussed. The author presents a microscopic eight-body model and a potential model for the calculation of the {sup 7}Be(p, {gamma}){sup 8}B cross section.
Date: August 1, 1997
Creator: Csoto, A.
Partner: UNT Libraries Government Documents Department

The Mass-8 experiment -- Measuring the {beta}-{alpha} angular correlations

Description: The objective of the Mass-8 experiment is to perform a precision test of the conservation of the vector current hypothesis and a search for second class currents. The authors present preliminary data on the correlation coefficients of the {beta}-{alpha} angular correlations of the {beta}-delayed {alpha}-decays of {sup 8}Li and {sup 8}B.
Date: December 31, 1997
Creator: Amsbaugh, J.F.; Beck, M.; Braeckeleer, L. de; Storm, D.W.; Swanson, E.; Swartz, K.B. et al.
Partner: UNT Libraries Government Documents Department

Nuclear physics input for solar models

Description: The authors discuss microscopic cluster model descriptions of two solar nuclear reactions, {sup 7}Be(p,{gamma}){sup 8}B, and {sup 3}He({sup 3}He, 2p){sup 4}He. The low-energy reaction cross section of {sup 7}Be(p,{gamma}){sup 8}B, which determines the high-energy solar neutrino flux, is constrained by {sup 7}Be and {sup 8}Be observables. The results show that a small value of the zero-energy cross section is rather unlikely. In {sup 3}He({sup 3}He, 2p){sup 4}He the authors study the effects of a possible virtual state on the cross section. Although, they have found no indication for such a state so far, its existence cannot be ruled out yet. They calculated the {sup 3}He({sup 3}He, 2p){sup 4}He and {sup 3}H({sup 3}H, 2n){sup 4}He cross sections in a continuum-discretized coupled channel approximation, and found a good general agreement with the data.
Date: March 1, 1998
Creator: Csoto, A.
Partner: UNT Libraries Government Documents Department

Neutral-current detectors for the Sudbury Neutrino Observatory

Description: With its heavy water target, the Sudbury Neutrino Observatory has the unique opportunity to measure both the {sup 8}B flux of electron neutrinos from the Sun and the flux of all active neutrino species independently, thus offering a direct and model-independent test of a neutrino oscillation solution to the solar neutrino problem. The authors report on the physics intent and design of a discrete method of neutral-current detection in the Sudbury neutrino observatory that will utilize ultra-low background {sup 3}He proportional counters dispersed throughout the heavy water volume. Projections of background in all components of the detector are considered in an analysis of the ability to extract the neutral-current signal and the neutral-current to charged-current ratio.
Date: September 1, 1997
Creator: Hime, A. & Collaboration, SNO
Partner: UNT Libraries Government Documents Department

Mass measurements of highly neutron-excess nuclei in the light elements

Description: The $sup 26$Mg($sup 7$Li,$sup 8$B)$sup 25$Ne reaction at 78.9 MeV was used to measure the mass-excess of $sup 25$Ne (-2.18 +- 0.10 MeV) and several low- lying excited states. Mass-excesses for $sup 43$Ar (-31.98 +- 0.07 MeV), $sup 45$Ar (-29.727 +- 0.06 MeV), and $sup 46$Ar (-29.732 +- 0.07 MeV) were determined from the $sup 48$Ca($alpha$,$sup 9$,$sup 7$Be)$sup 43$,$sup 45$Ar reactions at 77.7 MeV and the $sup 48$Ca($sup 6$Li,$sup 8$B)$sup 46$Ar reaction at 80.1 MeV. Several excited states of $sup 43$Ar and $sup 45$Ar were observed. These and the excited states of $sup 25$Ne are compared with theoretical predictions. Ground state differential cross sections are given for all reactions, ranging from 0.1 to 1 $mu$b/sr at forward angles. Upper limits of about 1 to 25 nb/sr were determined for the ground state cross sections of the reactions $sup 48$Ca($alpha$,$sup 8$,$sup 10$,$sup 11$B)$sup 44$,$sup 42$,$sup 41$Cl and $sup 48$Ca($alpha$,$sup 10$-$sup 13$C)$sup 42$-$sup 39$S at 110 MeV. Recoil coincidence techniques were used to measure the mass-excess of the particle- unbound nucleus $sup 10$Li(33.83 +- 0.25 MeV) by the $sup 9$Be($sup 9$Be,$sup 8$B)$sup 10$Li reaction at 121 MeV; the ground state cross section was 30 nb/sr. The $sup 14$C($sup 9$Be,$sup 8$B)$sup 15$B reaction at 120 MeV was also investigated using coincidence techniques. Contamination problems only permitted determining a ground state cross section upper limit of 50 nb/sr. A simple mass relation is derived, similar in approach to the Garvey-Kelson method but taking more explicit account of shell effects. Comparison is made with the Garvey- Kelson relation, and predictions of masses and of the stability of neutron-excess light nuclei are given for both methods. The modified mass relation is shown to offer better account for highly neutron-excess nuclei, including the values reported here for $sup 25$Ne and $sup 43$,$sup 45$,$sup 46$Ar. (26 figures, 2 ...
Date: May 1, 1975
Creator: Wilcox, K.H.
Partner: UNT Libraries Government Documents Department

Annual report of the Nuclear Physics Laboratory, University of Washington

Description: The Nuclear Physics Laboratory of the University of Washington has for over 40 years supported a broad program of experimental physics research. Some highlights of the research activities during the past year are given. Work continues at a rapid pace toward completion of the Sudbury Neutrino Observatory in January 1997. Following four years of planning and development, installation of the acrylic vessel began last July and is now 50% complete, with final completion scheduled for September. The Russian-American Gallium Experiment (SAGE) has completed a successful {sup 51}Cr neutrino source experiment. The first data from {sup 8}B decay have been taken in the Mass-8 CVC/Second Class Current study. The analysis of the measured barrier distributions for Ca-induced fission of prolate {sup 192}Os and oblate {sup 194}Pt has been completed. In a collaboration with a group from the Bhabha Atomic Research Centre they have shown that fission anisotropies at energies well above the barrier are not influenced by the mass asymmetry of the entrance channel relative to the Businaro-Gallone critical asymmetry. They also have preliminary evidence at higher bombarding energy that noncompound nucleus fission scales with the mean square angular momentum, in contrast to previous suggestions. The authors have measured proton and alpha particle emission spectra from the decay of A {approximately} 200 compound nuclei at excitation energies of 50--100 MeV, and used these measurements to infer the nuclear temperature. The investigations of multiparticle Bose-Einstein interferometry have led to a new algorithm for putting Bose-Einstein and Coulomb correlations of up to 6th order into Monte Carlo simulations of ultra-relativistic collision events, and to a new fast algorithm for extracting event temperatures.
Date: April 1, 1996
Creator: Snover, K. & Fulton, B.
Partner: UNT Libraries Government Documents Department

MSW effect and solar neutrino experiments

Description: We describe the MSW solutions to the /sup 37/Cl solar neutrino experiment, and their implications for the /sup 71/Ga experiment. Measurement of the spectrum of electron-type neutrinos arriving at earth is emphasized. 8 refs., 2 figs., 1 tab.
Date: January 1, 1986
Creator: Rosen, S.P.
Partner: UNT Libraries Government Documents Department

Molybdenum solar neutrino experiment

Description: The goal of the molybdenum solar neutrino experiment is to deduce the /sup 8/B solar neutrino flux, averaged over the past several million years, from the concentration of /sup 98/Tc in a deeply buried molybdenum deposit. The experiment is important to an understanding of stellar processes because it will shed light on the reason for the discrepancy between theory and observation of the chlorine solar neutrino experiment. Possible reasons for the discrepancy may lie in the properties of neutrinos (neutrino oscillations or massive neutrinos) or in deficiencies of the standard solar model. The chlorine experiment only measures the /sup 8/B neutrino flux in current times and does not address possible temporal variations in the interior of the sun, which are also not considered in the standard model. In the molybdenum experiment, we plan to measure /sup 98/Tc (4.2 Myr), also produced by /sup 8/B neutrinos, and possibly /sup 97/Tc (2.6 Myr), produced by lower energy neutrinos.
Date: January 1, 1984
Creator: Wolfsberg, K.; Cowan, G.A.; Bryant, E.A.; Daniels, K.S.; Downey, S.W.; Haxton, W.C. et al.
Partner: UNT Libraries Government Documents Department

Solar neutrino physics in the nineties

Description: The decade of the 1990's should prove to be landmark period for the study of solar neutrino physics. Current observations show 2--3 times fewer neutrinos coming from the sun than are theoretically expected. As we enter the decade, new experiments are poised to attempt and discover whether this deficit is a problem with our understanding of how the sun works, is a hint of new neutrino properties beyond those predicted by the standard model of particle physics, or perhaps a combination of both. This paper will briefly review the current status of the field and point out how future measurements should help solve this interesting puzzle. 11 refs., 3 figs., 1 tab.
Date: January 1, 1990
Creator: Wilkerson, J.F.
Partner: UNT Libraries Government Documents Department

(. pi. /sup +/,p) and (. pi. /sup +/,d) reactions on light nuclei. [32 to 81 MeV]

Description: The (..pi../sup +/,p) and (..pi../sup +/,d) reactions on 1p shell nuclei are studied between T/sub ..pi../ = 32 and 81 MeV. The cross sections to both the continuum and discrete two-body final states are given. The spectra and angular distributions of the (..pi../sup +/,p) continuum are interpreted in terms of a two-nucleon pion absorption mechanism. The /sup 13/C(..pi../sup +/,p) spectrum of discrete states is similar to the /sup 13/C(p,d) spectrum at the same momentum transfer. The two-neutron-pickup (..pi..,d) reaction is found to strongly favor transitions in the 1p shell of angular momentum transfer, L = 2. The relative strength of these transitions varies the same way as the corresponding (p,t) cross sections. No L = 0 transitions are clearly identifiable. There is an indication of the S = 1 /sup 7/Li(..pi../sup +/,d)/sup 5/Li(16.7 MeV) 3/2/sup +/ transition, contrary to the prediction that S = 1 transitions are suppressed. The (..pi../sup +/,d) angular distributions are compared to the calculations of Betz and Kerman. 2 tables.
Date: unknown
Creator: Doss, K. G. R.; Barnes, P. D.; Colella, N.; Dytman, S. A.; Eisenstein, R. A.; Ellegaard, C. et al.
Partner: UNT Libraries Government Documents Department

Leap to explore the region of neutron-rich heavy element isotopes

Description: The research aims of the Large Einsteinium Activation Program (LEAP) are described. This program is a major initiative to exploit currently existing expertise in heavy element research and the potential for producing very heavy actinide target materials such as 285-day /sup 254/Es at the High Flux Isotope Reactor at Oak Ridge National Laboratory. The stated aims of the program are to produce heavy element isotopes, to conduct chemical studies of these isotopes, to study the nuclear properties of such isotopes, and to produce a superheavy element (183 neutrons) by the using a /sup 254/Es target and /sup 48/Ca projectiles. 13 refs., 2 figs., 2 tabs. (DWL)
Date: October 1, 1985
Creator: Hoffman, D.C.
Partner: UNT Libraries Government Documents Department

Pion absorption processes. [32 to 74 MeV]

Description: Proton and deuteron production from low-energy pion absorption in light nuclei leading to discrete and continuum states were measured. The LEP beam line at LAMPF was used with a stack of 8 intrinsic germanium crystals. The proton energy spectra are in general characterized by a broad bump at an energy approximately corresponding to ..pi../sup +/d ..-->.. pp reaction kinematics, suggestive of pion absorption on 2 nucleons. The energy-integrated cross-section for production of deuterons has an angular distribution similar to that for production of protons. The dependence of the total pion absorption cross-section on A is explained using a semi-classical model for pion transport in nuclei. The (..pi../sup +/,p) as well as (..pi../sup +/,d) reactions generally favor transitions involving larger angular momentum transfer to the residual nucleus when states of similar nuclear structure are considered. The low-energy excitation spectra from the (..pi../sup +/,p) reaction are similar to the spectra from (p,d) reaction on /sup 12/C and /sup 13/C. However, a calculation of the (..pi.. = ,p) cross-section using the measured (p,d) reaction with the formulation of Wilkin to relate the two reactions is in moderate disagreement with the measured (..pi../sup +/,p) cross-sections. The excitation spectra from the (..pi../sup +/,p) reaction indicte the importance of two-step processes for the reaction. The (..pi../sup +/,d) reaction leading to the ground state of -- residual nucleus has been seen for /sup 7/Li, /sup 12/C, and /sup 13/C targets. The measured cross section for the /sup 12/C(..pi../sup +/,d)/sup 10/C reaction to the 2/sup +/ state is much higher than that for the ground state. For the case of /sup 18/O, no counts were seen for excitation energy of < 10 MeV, at a sensitivity of approx. 100 nb/sr count. These features indicate a possible failure of the model of Betz and Kerman for the (..pi../sup +/,d) ...
Date: April 1, 1980
Creator: Doss, K G.R.
Partner: UNT Libraries Government Documents Department