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Probing Novel Properties of Nucleons and Nuclei via Parity Violating Electron Scattering

Description: This thesis reports on two experiments conducted by the HAPPEx (Hall A Proton Parity Experiment) collaboration at the Thomas Je#11;erson National Accelerator Facil- ity. For both, the weak neutral current interaction (WNC, mediated by the Z{sup 0} boson) is used to probe novel properties of hadronic targets. The WNC interaction amplitude is extracted by measuring the parity-violating asymmetry in the elastic scattering of longitudinally polarized electrons o#11; unpolarized target hadrons. HAPPEx-III, con- ducted in the Fall of 2009, used a liquid hydrogen target at a momentum transfer of Q{sup 2} = 0.62 GeV{sup 2}. The measured asymmetry was used to set new constraints on the contribution of strange quark form factors (G{sup s}{sub E,M} ) to the nucleon electromagnetic form factors. A value of A{sub PV} = -23.803{+-}#6; 0.778 (stat){+-}#6; 0.359 (syst) ppm resulted in G{sup s}{sub E} + 0:517G{sup s}{sub M} = 0.003{+-} 0.010 (stat){+-} #6;0.004 (syst){+-}#6; #6;0.009 (FF). PREx, conducted in the Spring of 2010, used a polarized electron beam on a 208Pb target at a momentum transfer of Q{sup 2} = 0.009 GeV{sup 2}. This parity-violating asymmetry can be used to obtain a clean measurement of the root-mean-square radius of the neutrons in the {sup 208}Pb nucleus. The Z{sup 0} boson couples mainly to neutrons; the neutron weak charge is much larger than that of the proton. The value of this asymmetry is at the sub-ppm level and has a projected experimental fractional precision of 3%. We will describe the accelerator setup used to set controls on helicity-correlated beam asymmetries and the analysis methods for #12;nding the raw asymmetry for HAPPEx-III. We will also discuss in some detail the preparations to meet the ex- perimental challenges associated with measuring such a small asymmetry with the degree of precision required for PREx.
Date: May 31, 2012
Creator: Mercado, Luis
Partner: UNT Libraries Government Documents Department

QUARTERLY REPORT, JANUARY 1, 1960-MARCH 31, 1960

Description: Three methods for the determination of radium were evaluated. In two methods, the radium is finally precipitated with barium sulfate as carrier and alpha-counted. In the other method, the radium is recovered in a carrierfree condition for alpha counting. A method for determining radium by removing interfering elements with solvent extraction technniques and precipitating the radium with barium sulfate is described. A method which gives a rapid estimation of radium isotopic composition in samples, based on precipitation with barium sulfate, conversion to the carbonate, and alpha counting, is described. Flowsheets are contained on all five processes discussed. Two processes for the determination of thorium were evaluated. One method consists essentially of extraction of carrierfree thorium in TTA-benzene, stripped in nitric acid, and direct plating of the nitric acid solution for counting. The second method consists of thorium precipitation on lanthanum hydroxide, then on lanthanum fluoride, dissolution in nitric acid aluminum nitrate, thorium extraction into TTA solution, stripping into nitric acid, and counting. Flowsheets for the processes are given. The effects of pH, sulfate ion concentration, calcium and other contaminants, and temperature on the adsorption of radium from acid leach liquors by barite were studied. Coprecipitation studies of radium with barium sulfate from mill effluent streams were investigated. (For preceding period see WlN-115.) (C.J.G.)
Date: October 31, 1960
Creator: Herrington, A.C. comp. and ed.
Partner: UNT Libraries Government Documents Department

Strange Particle Production in $p+p$ Collisions at $\sqrt{s}$= 200GeV

Description: We present strange particle spectra and yields measured atmid-rapidity in sqrt text s=200 GeV proton-proton (p+p) collisions atRHIC. We find that the previously observed universal transverse mass(mathrm mT \equiv\sqrt mathrm p_T 2+\mathrm m2) scaling of hadronproduction in p+p collisions seems to break down at higher \mt and thatthere is a difference in the shape of the \mt spectrum between baryonsand mesons. We observe mid-rapidity anti-baryon to baryon ratios nearunity for Lambda and Xi baryons and no dependence of the ratio ontransverse momentum, indicating that our data do not yet reach thequark-jet dominated region. We show the dependence of the mean transversemomentum (\mpt) on measured charged particle multiplicity and on particlemass and infer that these trends are consistent with gluon-jet dominatedparticle production. The data are compared to previous measurements fromCERN-SPS, ISR and FNAL experiments and to Leading Order (LO) and Next toLeading order (NLO) string fragmentation model predictions. We infer fromthese comparisons that the spectral shapes and particle yields from $p+p$collisions at RHIC energies have large contributions from gluon jetsrather than quark jets.
Date: July 31, 2006
Creator: Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett,J.; Anderson, B.D. et al.
Partner: UNT Libraries Government Documents Department

A geoneutrino experiment at Homestake

Description: A significant fraction of the 44 TW of heat dissipation from the Earth's interior is believed to originate from the decays of terrestrial uranium and thorium. The only estimates of this radiogenic heat, which is the driving force for mantle convection, come from Earth models based on meteorites, and have large systematic errors. The detection of electron antineutrinos produced by these uranium and thorium decays would allow a more direct measure of the total uranium and thorium content, and hence radiogenic heat production in the Earth. They discuss the prospect of building an electron antineutrino detector approximately 700 m{sup 3} in size in the Homestake mine at the 4850 feet level. This would allow us to make a measurement of the total uranium and thorium content with a statistical error less than the systematic error from the current knowledge of neutrino oscillation parameters. It would also allow us to test the hypothesis of a naturally occurring nuclear reactor at the center of the Earth.
Date: May 31, 2006
Creator: Tolich, Nikolai; Chan, Yuen-Dat; Currat, Charles A.; Decowski, M.Patrick; Fujikawa, Brian K.; Henning, Reyco et al.
Partner: UNT Libraries Government Documents Department

THREE NEW DELAYED ALPHA EMITTERS OF LOW MASS

Description: Two new positron active isotopes, B{sup 8} and Na{sup 20}, have been found to decay to excited states of Be{sup 8} and Ne{sup 20}, which in turn decay 'instantaneously' by alpha emission. Their half-lives are 0.65 {+-} 0.1 sec. and 1/4 sec. respectively. N{sup 12} is also found to have a low energy positron group which leads to an {alpha}-unstable excited state in C{sup 12}. The masses of B{sup 8} and Na{sup 20} are 8.027 and 20.015 respectively. B{sup 8} decays by a 13.7 {+-} 0.3 Mev positron, through the same excited state of Be{sup 8} as does Li{sup 8}. Estimates of the energies of the excited state in C{sup 12} and Ne{sup 20} are made.
Date: May 31, 1950
Creator: Alvarez, Luis W.
Partner: UNT Libraries Government Documents Department

USE OF SILICON SURFACE-BARRIER COUNTERS IN FAST-NEUTRON DETECTION AND SPECTROSCOPY

Description: A neutron-sensitive semiconductor counter was constructed by depositing a thin layer of Li/sup 6/F between two silicon surface-barrier counters. Neutrons are detected by observing the alpha + T pair resulting from the Li/sup 6/(n, alpha )T reaction; pulses from the two counters are added, and the sum pulse is amplified and recorded on a multichannel analyzer. Since the sandwich geometry permits simultaneous detection of both reaction products, the magnitude of the resulting sum pulse is proportional to the energy of the incoming neutron. Pulse-height spectra from slow neutrons and monoenergetic fast neutrons. in the energy region 0.6 to 3.5 Mev, were recorded from two counters of this type; in both counters the sensitive area was about 0.7 cm/sup 2/, with a Li/sup 6/F layer of order 150 mu g/cm thick. In all cases. a well defined neutron peak was observed in the pulse-height spectrum. In a typical case the full width at half maximum of the fast-neutron peak was about 300 kev. Counters of this type are relatively insensitive to background effects, notably gamma rays, and thus may prove to be useful in the detection and spectroscopy of fast neutrons. (auth)
Date: May 31, 1960
Creator: Love, T A & Murray, R B
Partner: UNT Libraries Government Documents Department

O.H. Module Vacuum Lifting Fixture

Description: In order to move the 800 lb. copper plates that make up the O.H. modules a vacuum lifting device has been made that will lift the plates safely. The purpose of this report is to provide documentation for the structural integrity of the system and to make sure that it passes all of the safety requirements that have been established for a system of this nature. The vacuum system is composed of a PIAB model M125 vacuum pump that has the pumping capacity of 27 in. Hg. This pump will produce vacuum for three 8 1/2 in. diameter suction cups or pads. A pressure gauge is fixed on the unit to allow the operator to continually monitor the pressure during all lifts. An additional safety feature is a mechanical vacuum monitoring device that is set to emit a shrill tone if the system vacuum falls below 24 in. Hg. A 'bleed' valve fixed on the unit will be used to let the system go to atmospheric pressure once the lift is complete. A 3 psi. check valve and a vacuum reserve of 384 in. is used to insure that the device will not just drop the object if the pump fails. A schematic for the pumping system is given in Figure 1.
Date: December 31, 1987
Creator: McGivern, Paul
Partner: UNT Libraries Government Documents Department

LAr Dewar Coil Feed Frame Pipe Analysis (Structural Analysis of General Structures, SAGS)

Description: This frame pipe analysis addresses the D0 LAr dewar Condenser tube (coil) feed pipe thermal contraction stresses and moments. The configuration is shown in PEI drawing C-32545, Rev 0, and the parameters detailed in the letter of November 20, 1989, located in appendix A. Note that all other thermal considerations for these condensing coils have been made in D0 EN 3740.512-234. The conclusion of this report is the feed lines, previously deemed appropriate without detailed analysis, have been demonstrated to be adequately designed for the intended service and require no further investigation.
Date: January 31, 1990
Creator: Parker, A.W.
Partner: UNT Libraries Government Documents Department

Crack Parameters

Description: One of the important variables in the design of the end cap calorimeter is the number of angular divisions that should be made in the face of the calorimeter array. While it would be ideal to have no such divisions, they are unavoidable because the maximum size for uranium sheets is less than the diameter of the array. These divisions create regions which are either partially or totally devoid of absorber and readout. It is the purpose of this note to analyze the effects of different parameters on the size of these cracks. This analysis assumes wedge shaped structures of significant depth (i.e. > 20% of the total depth). For such modules there are five variables which affect the size of a crack. They are: (1) The clearance between modules. The extent to which the module wall and the array extend into this region depends on the tolerances on the manufacture of the module. All of the module construction techniques currently under consideration have very tight tolerances (e.g. 2 mils). Therefore, this region is assumed to be void of solid material. In the C.C this region is thought to be .090 inches wide. (2) The thickness of the module walls. The wall thickness depends on which module is discussed. Design thicknesses range from .078 inches in the C.C. modules to .150 inches in the E.C leakage modules. Because tight tolerances are assumed on the construction of the modules the skin is assumed to be perfectly flat. (3) The dimension tolerance on the uranium width. The effect of the dimension tolerance varies depending on the location of the module. Modules near the a o'clock and 9 o'clock position will see a gray zone equal to the dimension tolerance at the top of each module. There will be a solid black zone ...
Date: October 31, 1985
Creator: Pitas, A.
Partner: UNT Libraries Government Documents Department

Argon Test Cell Coaxial Cable Feed Through Connector Testing

Description: Within each cryostat their will exist three Argon Monitoring Boxes. Located at different elevations these boxes are responsible for measuring the relative 'quality' of the Argon as far as it's ability to transfer electrons without recombination. Each box requires three miniature coaxial cables to provide a signal to the outside world. These cables are shielded in groups of three. Each cryostat requires three of these grouped cables which must pass through some form of feedthrough located in the Instrumentation Box. For reasons of minimizing crosstalk and signal loss it is best to provide uninterrupted coaxial service between the receiving device and the monitor boxes. In an attempt to provide such service Jerry Blazey obtained a connector whose manufacturer promised would provide uninterupted coaxial service. Results of cold shock and leakage tests preformed on this feedthrough comprise the remainder of this note. Under normal operating conditions this feed through would never reach temperatures as low as those used for these cold shock tests.
Date: October 31, 1988
Creator: Krasa, R.T.
Partner: UNT Libraries Government Documents Department

Long-Range Lepton Flavor Interactions and Neutrino Oscillations

Description: Recent results from the MINOS accelerator neutrino experiment suggest a possible difference between {nu}{sub {mu}} and {bar {nu}}{sub {mu}} disappearance oscillation parameters, which one may ascribe to a new long distance potential acting on neutrinos. As a specific example, we consider a model with gauged B - L{sub e} - 2L{sub {tau}} number which contains an extremely light new vector boson, m{sub Z}, < 10{sup -18} eV and extraordinarily weak coupling {alpha}{prime} {approx}< 10{sup -52}. In that case, differences between {nu}{sub {mu}} {yields} {nu}{sub {tau}} and {bar {nu}}{sub {mu}} {yields} {bar {nu}}{sub {tau}} oscillations can result from a long-range potential due to neutrons in the Earth and the Sun that distinguishes {nu}{sub {mu}} and {nu}{sub {tau}} on Earth, with a potential difference of {approx} 6 x 10{sup -14} eV, and changes sign for anti-neutrinos. We show that existing solar, reactor, accelerator, and atmospheric neutrino oscillation constraints can be largely accommodated for values of parameters that help explain the possible MINOS anomaly by this new physics, although there is some tension with atmospheric constraints. A long-range interaction, consistent with current bounds, could have very pronounced effects on atmospheric neutrino disappearance in the 20-50 GeV range that will be studied with the IceCube DeepCore array, currently in operation, and can have a significant effect on future high-precision long-baseline oscillation experiments which aim for {+-}1% sensitivity, in {nu}{sub {mu}} and {bar {nu}}{sub {mu}} disappearance, separately. Together, these experiments can extend the reach for new long-distance effects well beyond current bounds and test their relevance to the aforementioned MINOS anomaly. We also point out that long-range potentials originating from the Sun could lead to annual modulations of neutrino data at the percent level, due to the variation of the Earth-Sun distance. A similar phenomenology is shown to apply to other potential new gauge symmetries ...
Date: March 31, 2011
Creator: Davoudiasl, H.; Lee, H-S & Marciano, W.
Partner: UNT Libraries Government Documents Department

PRELIMINARY CROSS SECTION AND NU-BAR COVARIANCES FOR WPEC SUBGROUP 26

Description: We report preliminary cross section covariances developed for the WPEC Subgroup 26 for 45 out of 52 requested materials. The covariances were produced in 15- and 187-group representations as follows: (1) 36 isotopes ({sup 16}O, {sup 19}F, {sup 23}Na, {sup 27}Al, {sup 28}Si, {sup 52}Cr, {sup 56,56}Fe, {sup 58}Ni, {sup 90,91,92,94}Zr, {sup 166,167,168,170}Er, {sup 206,207,208}Pb, {sup 209}Bi, {sup 233,234,236}U, {sup 237}Np, {sup 238,240,241,242}Pu, {sup 241,242m,243}Am, {sup 242,243,244,245}Cm) were evaluated using the BNL-LANL methodology. For the thermal region and the resolved and unresolved resonance regions, the methodology has been based on the Atlas-Kalman approach, in the fast neutron region the Empire-Kalman method has been used; (2) 6 isotopes ({sup 155,156,157,158,160}Gd and {sup 232}Th) were taken from ENDF/B-VII.0; and (3) 3 isotopes ({sup 1}H, {sup 238}U and {sup 239}Pu) were taken from JENDL-3.3. For 6 light nuclei ({sup 4}He, {sup 6,7}Li, {sup 9}Be, {sup 10}B, {sup 12}C), only partial cross section covariance results were obtained, additional work is needed and they do not report the results here. Likewise, the cross section covariances for {sup 235}U, which they recommend to take from JENDL-3.3, will be included once the multigroup processing is successfully completed. Covariances for the average number of neutrons per fission, total {nu}-bar, are provided for 10 actinides identified as priority by SG26. Further work is needed to resolve some of the issues and to produce covariances for the full set of 52 materials.
Date: January 31, 2007
Creator: ROCHMAN,D.
Partner: UNT Libraries Government Documents Department

Investigation of Beam Instability Under the Effects of Long-Range Transverse Wake Fields in the Berkeley Future Light Source

Description: An ultra-relativistic charged particle bunch moving through a resonator cavity leaves behind a wake field that will affect subsequent bunches (if the bunch is not ultra-relativistic, the wake field will not be exclusively behind it). If the initial bunch enters the cavity off-axis, it will produce a transverse wake field that can then kick later bunches off the axis. Thus, even bunches that were initially traveling on axis could be displaced and, in turn, produce their own transverse wake fields, affecting following bunches. The offsets obtained by bunches could increase along the bunch train, leading to the so-called multi-bunch beam break-up instability [1]. The purpose of our investigation is to see whether such instability will occur in the superconducting, 1.3 GHz, 2.5GeV linac (see Table 1) planned for the Berkeley future light source (BFLS). We assume an initial steady-state situation established for machine operation; i.e. a continuous process where every bunch follows the same trajectory through the linac, with only small deviations from the axis of the rf structures. We will look at a possible instability arising from a bunch having a small deviation from the established trajectory. Such a deviation would produce a wake field that is slightly different from the one produced by the bunches following the established trajectory. This could lead to subsequent bunches deviating further from the established trajectory. We will assume the deviations are small (at first) and so the difference in the wake field caused by a bunch not traveling along the established trajectory is well approximated by a long-range transverse dipole wake. We are concerned only with deviations from the established trajectory; thus, in our models, a transverse position of zero corresponds to the bunch traveling along the established trajectory. Under this assumption, only the additional long-range transverse dipole wake remains in our ...
Date: August 31, 2008
Creator: Kur, Eugene & Zholents, Alexander A.
Partner: UNT Libraries Government Documents Department