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Neutrino observations from the Sudbury Neutrino Observatory

Description: The Sudbury Neutrino Observatory (SNO) is a water imaging Cherenkov detector. Its usage of 1000 metric tons of D{sub 2}O as target allows the SNO detector to make a solar-model independent test of the neutrino oscillation hypothesis by simultaneously measuring the solar {nu}{sub e} flux and the total flux of all active neutrino species. Solar neutrinos from the decay of {sup 8}B have been detected at SNO by the charged-current (CC) interaction on the deuteron and by the elastic scattering (ES) of electrons. While the CC reaction is sensitive exclusively to {nu}{sub e}, the ES reaction also has a small sensitivity to {nu}{sub {mu}} and {nu}{sub {tau}}. In this paper, recent solar neutrino results from the SNO experiment are presented. It is demonstrated that the solar flux from {sup 8}B decay as measured from the ES reaction rate under the no-oscillation assumption is consistent with the high precision ES measurement by the Super-Kamiokande experiment. The {nu}{sub e} flux deduced from the CC reaction rate in SNO differs from the Super-Kamiokande ES results by 3.3{sigma}. This is evidence for an active neutrino component, in additional to {nu}{sub e}, in the solar neutrino flux. These results also allow the first experimental determination of the total active {sup 8}B neutrino flux from the Sun, and is found to be in good agreement with solar model predictions.
Date: September 24, 2001
Creator: Ahmad, Q.R.; Allen, R.C.; Andersen, T.C.; Anglin, J.D.; Barton,J.C.; Beier, E.W. et al.
Partner: UNT Libraries Government Documents Department

MEASUREMENT OF SPECTRAL DISTRIBUTION OF POSITRON FLUX IN AN INFINITE COPPER MEDIUM CONTAINING Cu$sup 64$ (thesis)

Description: The spectral distribution of the flux of positrons inside a beta radioactive medium was experimentally determined using an anthracene coincidence scintillation spectrometer. Positrons leaving a copper cavity source containing Cu/sup 64/ were absorbed in a thin anthracene crystal. The light pulse from the anthracene was recorded in a 256 channel analyzer if a NaI scintillation spectrometer nearby recorded simultaneously a count under the total absorption peak for annihilation radiation. Thus, discrimination against negative and secondary electrons was obtained which permitted observation of the primary positron slowing down flux. Data were corrected for the non-linear pulse height vs energy relationship in anthracene by a semi-empirical theory due to Birks, the validity of which was demonstrated by its use in obtaining a linear Fermi plot of Pm/sup 147/. Positron spectra were corrected also for Compton absorption of the annihilation radiation in the anthracene. Results were compared with the theoretical continuous-slowing-down model. Over the energy range measured (20-- 650 kev) it was concluded that the continuous-slowing-down model gives the correct shape for the primary slowing-down spectrum. 43 references. (auth)
Date: December 24, 1963
Creator: Wilkie, W.H. & Birkhoff, R.D.
Partner: UNT Libraries Government Documents Department

Low Temperature Thermal Expansion of G-10 Plastic and Mylar

Description: This engineering note is a summary of test information and conclusions from the thermal expansion tests conducted at D-O during the fall of 1992. Each test was conducted separately but using the same basic procedure and equipment. While information on material properties at room temperature and above for these products is quite well doccumented, the companies producing these products had no available data about the thermal properties of these materials at cryogenic temperatures. This lack of readily available information prompted these tests to determine the accuracy of using the elevated temperature data for lower temperatures also. The results of each test were written up separately as stand alone short reports for immediate use in the design stages of the V.L.P.C. cryostat cassette. Both short reports are gathered here for convenient reference.
Date: May 24, 1993
Creator: Bell, D.
Partner: UNT Libraries Government Documents Department

Tauwer Test

Description: TAUWER is a proposed astroparticle experiment to detect ultrahigh energy TAU neutrinos, using detector towers arrayed on a mountainside looking down into a valley. This test is to study the possibility of replacing Hamamatsu miniature PMTs with SiPMs for readout by determining the response of scintillation detectors with SiPM readout to low energy electrons, 2 GeV or lower, as the beam will provide. The detector itself is a compact package shown in the picture on the cover. it was used in a parasitic test beam run on December 15, 2010, to compare the relative timing of the signals from three counters for MIPs. The only change for this new run is the insertion of 1.5 cm of Pb in front of counter 2 or counter 3 during most of the running. The experiment takes some electron data without Pb for calibration purposes. The apparatus will be mounted on the moving table in MT6.2B.
Date: January 24, 2011
Creator: Russ, James; U., /Carnegie Mellon; Iori, Maurizio; U., /Rome; Ronzhin, Anatoly & /Fermilab
Partner: UNT Libraries Government Documents Department

D0 Clean Room ODH Analysis

Description: Table A shows the steady state situation. One ofthe two dewars would be supplying purge gas at (a maximum of) 20 scfm, which would leak: into the room through the welding orifice. Instantaneous uniform diffusion and exhaust are assumed. Note the probability is 1 for the 20 scfm leak since it is a planned occurrence. Table B is the same situation in the event of a power failure, estimated for twice a year (2.29 x 10{sup -4} fails/hour). This assumes that the exhaust is shut down, and the dewars are not turned off. This would require the minimum exhaust to be the same as the leak: (as an approximation). These results, however, would only be valid for an infinite supply of the purge gas, and for an exceedingly long power failure. Since the supply of LAr would only last a day at most, and the power failure would not last for weeks, this result has no real significance. In fact, the time constant for the ODH equation in this case is 5717 minutes, which means it would take 20 days for all the oxygen to be displaced. A worst case scenario would be a full dewar completely emptying into the clean room in a short time relative to the ventilation rate, but slow enough for uniform dispersion. We can do a leak/exhaust independent (ventilation rate=O) analysis. This also assumes instantaneous and uniform mixing. This suggests that even with a complete dewar failure, the oxygen content would not decrease to a safety hazard. The probability ofa simultaneous, catastrophic. dewar failure would be so low as to offset the consequences as insIgnificant, and even so. those consequences would be only a slight oxygen deficiency (17.5% 0{sub 2}) These same arguments could be followed for LN2 dewarst and would have the same results ...
Date: May 24, 1990
Creator: Michael, J.
Partner: UNT Libraries Government Documents Department

MFH Top-Half Ring Connectros

Description: In the end calorimeter of the D-zero experiment, uranium and stainless steel plates are assembled into modules which are to be installed into the cryostat as individual units. A single inner module will be surrounded by 16 middle modules, which are surrounded by 16 outer modules. The 16 modules which comprise the middle ring are to be connected at the outer radius by a link, which is pinned to each front plate. The expected forces at each of the 16 connections vary from 1400 Ib to 69,000 lb (Appendix 1). At the inner radius. the forces are known to be compressive; hence, the edges of the front plates will be allowed to bear directly upon one another. Since it is desirable to minimize the volume of material used, an Inconnel connector plate and pins were chosen. Furthermore, it was observed that the forces between the 9 modules of the top half of the ring are all less than 7,700 lb. Accordingly, a connector was designed for the top half of the ring, with the intention that a separate design be performed for the bottom connections. The purpose of the test was to experimentally verify that the connector scheme designed for the top half of the MH ring (end calorimeter) was adequate for the expected structural loads. The test proved that the design was acceptable.
Date: October 24, 1988
Creator: Nachtrieb, Rob
Partner: UNT Libraries Government Documents Department

Sigma: Web Retrieval Interface for Nuclear Reaction Data

Description: The authors present Sigma, a Web-rich application which provides user-friendly access in processing and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The main interface includes browsing using a periodic table and a directory tree, basic and advanced search capabilities, interactive plots of cross sections, angular distributions and spectra, comparisons between evaluated and experimental data, computations between different cross section sets. Interactive energy-angle, neutron cross section uncertainties plots and visualization of covariance matrices are under development. Sigma is publicly available at the National Nuclear Data Center website at www.nndc.bnl.gov/sigma.
Date: June 24, 2008
Creator: Pritychenko,B. & Sonzogni, A.A.
Partner: UNT Libraries Government Documents Department

Neutron Cross Section Uncertainties in the Thermal and Resonance Regions

Description: In the 'Atlas of Neutron Resonances', special care was expended to ensure that the resonance parameter information reproduces the various measured thermal cross sections, as well as the infinite dilute resonance integrals for Z = 1-100. In contrast, the uncertainties of the recommended quantities do not match those generated from the uncertainties of the resonance parameters. To address this problem, the present study was initiated to achieve consistency for 15 actinides and 21 structural and coolant moderator materials. This is realized by assigning uncertainties to the parameters of the negative-energy resonances and changing, if necessary, significantly the uncertainties of the low-lying positive-energy resonances. The influence of correlations between parameters on the derived uncertainties is examined and discussed.
Date: June 24, 2008
Creator: Mughabghab,S.F. & Oblozinsky, P.
Partner: UNT Libraries Government Documents Department

High gain FEL amplification of charge modulation caused by a hadron

Description: In scheme of coherent electron cooling (CeC) [1,2], a modulation of electron beam density induced by a copropagation hadron is amplified in high gain FEL. The resulting amplified modulation of electron beam, its shape, form and its lethargy determine number of important properties of the coherent electron cooling. In this talk we present both analytical and numerical (using codes RON [3] and Genesis [4]) evaluations of the corresponding Green functions. We also discuss influence of electron beam parameters on the FEL response.
Date: August 24, 2008
Creator: Litvinenko,V.; Ben-Zvi, I.; Hao, Y.; Kayran, D.; Pozdeyev, E.; Wang, G. et al.
Partner: UNT Libraries Government Documents Department

Can cross sections be accurately known for priori?

Description: Distinct maxima and minima in the neutron total cross section uncertainties were observed in our large scale covariance calculations using a spherical optical potential. In this contribution we investigate the physical origin of this oscillating structure. Specifically, we analyze the case of neutron reactions on {sup 56}Fe, for which total cross section uncertainties are characterized by the presence of five distinct minima at 0.1, 1.1, 5, 25, and 70 MeV. To investigate their origin, we calculated total cross sections by perturbing the real volume depth V{sub v} by its expected uncertainty {+-}{Delta}V{sub v}. Inspecting the effect of this perturbation on the partial wave cross sections we found that the first minimum (at 0.1 MeV) is exclusively due to the contribution of the s-wave. On the other hand, the same analysis at 1.1 MeV showed that the minimum is the result of the interplay between s-, p-, and d-waves; namely the change in the s-wave happens to be counterbalanced by changes in the p- and d-waves. Similar considerations can be extended for the third minimum, although it can be also explained in terms of the Ramsauer effect as well as the other ones (at 25 and 70 MeV). We discuss the potential importance of these minima for practical applications as well as the implications of this work for the uncertainties in total and absorption cross sections.
Date: June 24, 2008
Creator: Pigni,M.T.; Dietrich, F.S.; Herman, M. & Oblozinsky, P.
Partner: UNT Libraries Government Documents Department

Estimated 55Mn and 90Zr cross section covariances in the fast neutron energy region

Description: We completed estimates of neutron cross section covariances for {sup 55}Mn and {sup 90}Zr, from keV range to 25 MeV, considering the most important reaction channels, total, elastic, inelastic, capture, and (n,2n). The nuclear reaction model code EMPIRE was used to calculate sensitivity to model parameters by perturbation of parameters that define the optical model potential, nuclear level densities and strength of the pre-equilibrium emission. The sensitivity analysis was performed with the set of parameters which reproduces the ENDF/B-VII.0 cross sections. The experimental data were analyzed and both statistical and systematic uncertainties were extracted from almost 30 selected experiments. Then, the Bayesian code KALMAN was used to combine the sensitivity analysis and the experiments to obtain the evaluated covariance matrices.
Date: June 24, 2008
Creator: Pigni,M.T.; Herman, M. & Oblozinsky, P.
Partner: UNT Libraries Government Documents Department

Development of covariance capabilities in EMPIRE code

Description: The nuclear reaction code EMPIRE has been extended to provide evaluation capabilities for neutron cross section covariances in the thermal, resolved resonance, unresolved resonance and fast neutron regions. The Atlas of Neutron Resonances by Mughabghab is used as a primary source of information on uncertainties at low energies. Care is taken to ensure consistency among the resonance parameter uncertainties and those for thermal cross sections. The resulting resonance parameter covariances are formatted in the ENDF-6 File 32. In the fast neutron range our methodology is based on model calculations with the code EMPIRE combined with experimental data through several available approaches. The model-based covariances can be obtained using deterministic (Kalman) or stochastic (Monte Carlo) propagation of model parameter uncertainties. We show that these two procedures yield comparable results. The Kalman filter and/or the generalized least square fitting procedures are employed to incorporate experimental information. We compare the two approaches analyzing results for the major reaction channels on {sup 89}Y. We also discuss a long-standing issue of unreasonably low uncertainties and link it to the rigidity of the model.
Date: June 24, 2008
Creator: Herman,M.; Pigni, M.T.; Oblozinsky, P.; Mughabghab, S.F.; Mattoon, C.M.; Capote, R. et al.
Partner: UNT Libraries Government Documents Department

Measurement of electron clouds in large accelerators by microwave dispersion

Description: Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation at high currents. Furthermore, it is difficult to probe their density over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave transmitted over a section of the accelerator and used it to measure the average electron cloud density over a 50 m section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center.
Date: January 24, 2008
Creator: Desantis, Stefano; De Santis, Stefano; Byrd, John M.; Sonnad, Kiran G.; Pivi, Mauro T.F.; Krasnykh, Anatoly et al.
Partner: UNT Libraries Government Documents Department

Final Technical Report on STTR Project DE-FG02-06ER86282 Development and Demonstration of 6-Dimensional Muon Beam Cooling

Description: The overarching purpose of this project was to prepare a proposal for an experiment to demonstrate 6-dimensional muon beam cooling. The technical objectives were all steps in preparing the proposal, which was successfully presented to the Fermilab Accelerator Advisory Committee in February 2009. All primary goals of this project have been met.
Date: May 24, 2011
Creator: Muons, Inc.
Partner: UNT Libraries Government Documents Department

Emergence of the Persistent Spin Helix in Semiconductor Quantum Wells

Description: According to Noether's theorem, for every symmetry in nature there is a corresponding conservation law. For example, invariance with respect to spatial translation corresponds to conservation of momentum. In another well-known example, invariance with respect to rotation of the electron's spin, or SU(2) symmetry, leads to conservation of spin polarization. For electrons in a solid, this symmetry is ordinarily broken by spin-orbit (SO) coupling, allowing spin angular momentum to flow to orbital angular momentum. However, it has recently been predicted that SU(2) can be recovered in a two-dimensional electron gas (2DEG), despite the presence of SO coupling. The corresponding conserved quantities include the amplitude and phase of a helical spin density wave termed the 'persistent spin helix' (PSH). SU(2) is restored, in principle, when the strength of two dominant SO interactions, the Rashba ({alpha}) and linear Dresselhaus ({beta}{sub 1}), are equal. This symmetry is predicted to be robust against all forms of spin-independent scattering, including electron-electron interactions, but is broken by the cubic Dresselhaus term ({beta}{sub 3}) and spin-dependent scattering. When these terms are negligible, the distance over which spin information can propagate is predicted to diverge as {alpha} {yields} {beta}{sub 1}. Here we observe experimentally the emergence of the PSH in GaAs quantum wells (QW's) by independently tuning {alpha} and {beta}{sub 1}. Using transient spin-grating spectroscopy (TSG), we find a spin-lifetime enhancement of two orders of magnitude near the symmetry point. Excellent quantitative agreement with theory across a wide range of sample parameters allows us to obtain an absolute measure of all relevant SO terms, identifying {beta}{sub 3} as the main SU(2) violating term in our samples. The tunable suppression of spin-relaxation demonstrated in this work is well-suited for application to spintronics.
Date: August 24, 2011
Creator: Koralek, Jake; Weber, Chris; Orenstein, Joe; Bernevig, Andrei; Zhang, Shoucheng; Mack, Shawn et al.
Partner: UNT Libraries Government Documents Department

Prompt Neutron Lifetime for the NBSR Reactor

Description: In preparation for the proposed conversion of the National Institute of Standards and Technology (NIST) research reactor (NBSR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel, certain point kinetics parameters must be calculated. We report here values of the prompt neutron lifetime that have been calculated using three independent methods. All three sets of calculations demonstrate that the prompt neutron lifetime is shorter for the LEU fuel when compared to the HEU fuel and longer for the equilibrium end-of-cycle (EOC) condition when compared to the equilibrium startup (SU) condition for both the HEU and LEU fuels.
Date: June 24, 2012
Creator: Hanson, A.L. & Diamond, D.
Partner: UNT Libraries Government Documents Department

Observation of Magnetic Resonances in Electron Clouds in a Positron Storage Ring

Description: The first experimental observation of magnetic resonances in electron clouds is reported. The resonance was observed as a modulation in cloud intensity for uncoated as well as TiN-coated aluminum surfaces in the positron storage ring of the PEP-II collider at SLAC. Electron clouds frequently arise in accelerators of positively charged particles, and severely impact the machines performance. The TiN coating was found to be an effective remedy, reducing the cloud intensity by three orders of magnitude.
Date: August 24, 2011
Creator: Pivi, M.T.F.; Ng, J.S.T.; Cooper, F.; Kharakh, D.; King, F.; Kirby, R.E. et al.
Partner: UNT Libraries Government Documents Department

GLAST LAT And Pulsars: What Do We Learn from Simulations?

Description: Gamma-ray pulsars are among the best targets for the Large Area Telescope (LAT) aboard the GLAST mission. The higher sensitivity, time and energy resolution of the LAT will provide data of fundamental importance to understand the physics of these fascinating objects. Powerful tools for studying the LAT capabilities for pulsar science are the simulation programs developed within the GLAST Collaboration. Thanks to these simulations it is possible to produce a detailed distribution of gamma-ray photons in energy and phase that can be folded through the LAT Instrument Response Functions (IRFs). Here we present some of the main interesting results from the simulations developed to study the discovery potential of the LAT. In particular we will focus on the capability of the LAT to discover new radio-loud gamma-ray pulsars, on the discrimination between Polar Cap and Outer Gap models, and on the LAT pulsar sensitivity.
Date: October 24, 2007
Creator: Razzano, Massimiliano; /Pisa U. /INFN, Pisa; Harding, Alice K. & /NASA, Goddard
Partner: UNT Libraries Government Documents Department

Parameterization of the Angular Distribution of Gamma Rays Produced by P-P Interaction in Astronomical Environment

Description: We present the angular distribution of gamma rays produced by proton-proton interactions in parameterized formulae to facilitate calculations in astrophysical environments. The parameterization is derived from Monte Carlo simulations of the up-to-date proton-proton interaction model by Kamae et al. (2005) and its extension by Kamae et al. (2006). This model includes the logarithmically rising inelastic cross section, the diffraction dissociation process and Feynman scaling violation. The extension adds two baryon resonance contributions: one representing the {Delta}(1232) and the other representing multiple resonances around 1600 MeV/c{sup 2}. We demonstrate the use of the formulae by calculating the predicted gamma-ray spectrum for two different cases: the first is a pencil beam of protons following a power law and the second is a fanned proton jet with a Gaussian intensity profile impinging on the surrounding material. In both cases we find that the predicted gamma-ray spectrum to be dependent on the viewing angle.
Date: September 24, 2007
Creator: Karlsson, Niklas; /SLAC; Kamae, Tuneyoshi & /SLAC /KIPAC, Menlo Park
Partner: UNT Libraries Government Documents Department

CP Violation in B0 decays to Charmonium and Charm Final States

Description: We report on measurements of time-dependent CP-violation asymmetries in neutral B meson decays to charmonium and charm final states. The results are obtained from a data sample of (467 {+-} 5) x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II B factory.
Date: September 24, 2008
Creator: Chen, Chunhui
Partner: UNT Libraries Government Documents Department