Hot Topics From BaBar Experiment (open access)

Hot Topics From BaBar Experiment

The authors search for a new light non-Standard Model CP-odd Higgs boson, A{sup 0}, decaying to {tau}{sup +}{tau}{sup -}, {mu}{sup +}{mu}{sup -}, and invisible in radiative decays of the {Upsilon}(2S) and {Upsilon}(3S). We search for the light scalar particle produced in single-photon decays of the {Upsilon}(3S) resonance through the process {Upsilon}(3S) {yields} {gamma}A{sup 0}, A{sup 0} {yields} invisible. We also search for evidence of an undetectable {Upsilon}(1S) decay recoiling against the dipion system. The data samples contain 99 x 10{sup 6} {Upsilon}(2S) and 122 x 10{sup 6} {Upsilon}(3S) decays collected by the BABAR detector at the SLAC PEP-II B factory.
Date: October 27, 2010
Creator: Godang, Romulus
Object Type: Article
System: The UNT Digital Library
Hot Topics in BaBar (open access)

Hot Topics in BaBar

The authors present recent results concerning the searches for light Higgs-like particles in the decay {Upsilon}(3S) {yields} {gamma}A{sup 0},A{sup 0} {yields} {mu}{sup +}{mu}{sup -} as well as for the lepton flavor violation in the decays {Upsilon}(3S) {yields} e{sup {+-}}{tau}{sup {-+}}, {mu}{sup {+-}}{tau}{sup {-+}} and {tau} {yields} 3l (l = e, {mu}) with the BABAR experiment.
Date: June 11, 2010
Creator: da Costa, Joao Firmino
Object Type: Article
System: The UNT Digital Library
Leptonic Decays of the Charged B Meson (open access)

Leptonic Decays of the Charged B Meson

The authors present a search for the decay B{sup +} {yields} {ell}{sup +}{nu}{sub {ell}} ({ell} = {tau}, {mu}, or e) in (458.9 {+-} 5.1) x 10{sup 6} {Upsilon}(4S) decays recorded with the BABAR detector at the SLAC PEP-II B-Factory. A sample of events with one reconstructed exclusive semi-leptonic B decay (B{sup -} {yields} D{sup 0}{ell}{sup -}{bar {nu}}X) is selected, and in the recoil a search for B{sup +} {yields} {ell}{sup +}{nu}{sub {ell}} signal is performed. The {tau} is identified in the following channels: {tau}{sup +} {yields} e{sup +}{nu}{sub e}{bar {nu}}{sub {tau}}, {tau}{sup +} {yields} {mu}{sup +}{nu}{sub {mu}}{bar {nu}}{sub {tau}}, {tau}{sup +} {yields} {pi}{sup +}{bar {nu}}{sub {tau}}, and {tau}{sup +} {yields} {pi}{sup +}{pi}{sup 0}{bar {nu}}{sub {tau}}. The analysis strategy and the statistical procedure is set up for branching fraction extraction or upper limit determination. They determine from the dataset a preliminary measurement of {Beta}(B{sup +} {yields} {tau}{sup +}{nu}{sub {tau}}) = (1.8 {+-} 0.8 {+-} 0.1) x 10{sup -4}, which excludes zero at 2.4{sigma}, and f{sub B} = 255 {+-} 58 MeV. Combination with the hadronically tagged measurement yields {Beta}(B{sup +} {yields} {tau}{sup +}{nu}{sub {tau}}) = (1.8 {+-} 0.6) x 10{sup -4}. They also set preliminary limits on the branching fractions at …
Date: June 11, 2010
Creator: Corwin, Luke A.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Measurement of the Absolute Branching Fractions for $D^-_s\!\rightarrow\!\ell^-\bar{\nu}_{\ell}$ and Extraction of the Decay Constant $f_{D_s}$ (open access)

Measurement of the Absolute Branching Fractions for $D^-_s\!\rightarrow\!\ell^-\bar{\nu}_{\ell}$ and Extraction of the Decay Constant $f_{D_s}$

The absolute branching fractions for the decays D{sub s}{sup -} {yields} {ell}{sup -}{bar {nu}}{sub {ell}} ({ell} = e, {mu}, or {tau}) are measured using a data sample corresponding to an integrated luminosity of 521 fb{sup -1} collected at center of mass energies near 10.58 GeV with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at SLAC. The number of D{sub s}{sup -} mesons is determined by reconstructing the recoiling system DKX{gamma} in events of the type e{sup +}e{sup -}DKXD*{sub s}{sup -}, where D*{sub s}{sup -} {yields} D{sub s}{sup -}{gamma} and X represents additional pions from fragmentation. The D{sub s}{sup -} {yields} {ell}{sup 0}{nu}{sub {ell}} events are detected by full or partial reconstruction of the recoiling system DKX{gamma}{ell}. The branching fraction measurements are combined to determine the D{sub s}{sup -} decay constant f{sub D{sub s}} = (258.6 {+-} 6.4 {+-} 7.5) MeV, where the first uncertainty is statistical and the second is systematic.
Date: October 27, 2010
Creator: del Amo Sanchez, P.; Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J. et al.
Object Type: Article
System: The UNT Digital Library
Measurement of the Decay B to Omega L Nu with the BaBar Detector and Determination of V_Ub (open access)

Measurement of the Decay B to Omega L Nu with the BaBar Detector and Determination of V_Ub

We measure the branching fraction of the exclusive charmless semileptonic decay B {yields} {omega}{ell}{nu}{sub {ell}}, where {ell} is either an electron or a muon, with the charged B meson recoiling against a tag B meson decaying in the charmed semileptonic modes B {yields} D{ell}{nu}{sub {ell}} or B {yields} D*{ell}{nu}{sub {nu}}. The measurement is based on a dataset of 426.1 fb{sup -1} of e{sup +}e{sup -} collisions at a CM energy of 10.58 GeV recorded with the BABAR detector at the PEP-II asymmetric B Factory located at the SLAC National Accelerator Laboratory. We also calculate the relevant B {yields} {omega} hadronic form factors to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |V{sub ub}|.
Date: September 10, 2010
Creator: Nagel, Martin
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Measurements of B to V(Gamma) Decays (open access)

Measurements of B to V(Gamma) Decays

The standard model has been highly successful at describing current experimental data. However, extensions of the standard model predict particles that have masses at energy scales that are above the electroweak scale. The flavor-changing neutral current processes of the B meson are sensitive to the influences of these new physics contributions. These processes proceed through loop diagrams, thus allowing new physics to enter at the same order as the standard model. New physics may contribute to the enhancement or suppression of rate asymmetries or the decay rates of these processes. The transition B {yields} V{gamma} (V = K*(892), {rho}(770), {omega}(782), {phi}(1020)) represents radiative decays of the B meson that proceed through penguin processes. Hadronic uncertainties limit the theoretical accuracy of the prediction of the branching fractions. However, uncertainties, both theoretical and experimental, are much reduced when considering quantities involving ratios of branching fractions, such as CP or isospin asymmetries. The most dominant exclusive radiative b {yields} s transition is B {yields} K*{gamma}. We present the best measurements of the branching fractions, direct CP, and isospin asymmetries of B {yields} K*{gamma}. The analogous b {yields} d transitions are B {yields} {rho}{gamma} and B {yields} {omega}{gamma}, which are suppressed by a factor …
Date: September 2, 2010
Creator: Yarritu, Aaron K.
Object Type: Report
System: The UNT Digital Library
Effects of Temperature and Contamination on Mpcms Electrodes in 241-Ay-101 and 241-an-107 Tank Waste Simulants (open access)

Effects of Temperature and Contamination on Mpcms Electrodes in 241-Ay-101 and 241-an-107 Tank Waste Simulants

This report documents the results of tests designed to characterize the relationship between temperature and the measured potential of electrodes installed on multi-probe corrosion monitoring systems in waste tanks. This report also documents the results of tests designed to demonstrate the impact of liquid in-leakage into electrode bodies as well as the contamination of primary reference electrodes by diffusion through the electrode tip.
Date: March 26, 2010
Creator: Dahl, M. M.; Philo, S. L.; Edgemon, G. L.; Bell, J. L. S. & Moore, C. G.
Object Type: Report
System: The UNT Digital Library
Performace of Multi-Probe Corrosion Monitoring Systems at the Hanford Site (open access)

Performace of Multi-Probe Corrosion Monitoring Systems at the Hanford Site

Between 2007 and 2009, several different multi-probe corrosion monitoring systems were designed and installed in high-level nuclear waste tanks at the U.S. Department of Energy's Hanford Site in WaShington State. The probe systems are being monitored to ensure waste tanks operate in regions that minimize localized corrosion (i.e., pitting) and stress corrosion cracking. The corrosion monitoring systems have been installed in wastes with different chemistry types. An ongoing effort during the same time period has generated non-radioactive simulants that are tested in the laboratory to establish baseline corrosion monitoring system performance and characterize data to allow interpretation of readings from the multiple corrosion monitoring systems. Data collection from these monitoring systems has reached the point where the results allow comparison with the laboratory testing. This paper presents analytical results from the corrosion monitoring system development program.
Date: January 14, 2010
Creator: Carothers, K. D.; Boomer, K. D.; Anda, V. S.; Dahl, M. M. & Edgemon, G. L.
Object Type: Article
System: The UNT Digital Library
Implementation of the MPC and A Operations Monitorying (MOM) System at JSC PO Sevmas (open access)

Implementation of the MPC and A Operations Monitorying (MOM) System at JSC PO Sevmas

The Material Protection, Control and Accounting (MPC&A) Program has been working since 1994 with nuclear sites in Russia to upgrade the physical protection (PP) and material control and accounting (MC&A) functions at facilities containing weapons usable nuclear material. In early 2001, the MPC&A program initiated the MPC&A Operations Monitoring (MOM) Project to monitor facilities where MPC&A upgrades have been installed to provide increased confidence that personnel are present and vigilant, provide confidence that security procedures are being properly performed and provide additional assurance that nuclear materials have not been stolen. The MOM project began as a pilot project at the Moscow State Engineering Physics Institute (MEPhI) and a MOM system was successfully installed in October 2001. Following the success of the MEPhI pilot project, the MPC&A Program expanded the installation of MOM systems to several other Russian facilities, including the JSC 'PO' Sevmash', Severodvinsk, Russia. The MOM system was made operational at Sevmash in September, 2008. This paper will discuss the objectives of the MOM system installed at Sevmash and indicate how the objectives influenced the development of the conceptual design. The paper will also describe activities related to installation of the infrastructure and the MOM system at Sevmash. Experience …
Date: July 11, 2010
Creator: Monogarov, Andrei; Taranenko, Vladimir; Serov, Andrei; Duncan, Cristen; Brownell, Lorilee; Pratt, William T. et al.
Object Type: Article
System: The UNT Digital Library
The Sloan Digital Sky Survey-II: Photometry and Supernova Ia Light Curves from the 2005 Data (open access)

The Sloan Digital Sky Survey-II: Photometry and Supernova Ia Light Curves from the 2005 Data

We present ugriz light curves for 146 spectroscopically confirmed or spectroscopically probable Type Ia supernovae from the 2005 season of the SDSS-II Supernova survey. The light curves have been constructed using a photometric technique that we call scene modeling, which is described in detail here; the major feature is that supernova brightnesses are extracted from a stack of images without spatial resampling or convolution of the image data. This procedure produces accurate photometry along with accurate estimates of the statistical uncertainty, and can be used to derive photometry taken with multiple telescopes. We discuss various tests of this technique that demonstrate its capabilities. We also describe the methodology used for the calibration of the photometry, and present calibrated magnitudes and fluxes for all of the spectroscopic SNe Ia from the 2005 season.
Date: August 26, 2010
Creator: Holtzman, Jon A.; Marriner, John; Kessler, Richard; Sako, Masao; Dilday, Ben; Frieman, Joshua A. et al.
Object Type: Article
System: The UNT Digital Library
Ecosystem feedbacks to climate change in California: Development, testing, and analysis using a coupled regional atmosphere and land-surface model (WRF3-CLM3.5) (open access)

Ecosystem feedbacks to climate change in California: Development, testing, and analysis using a coupled regional atmosphere and land-surface model (WRF3-CLM3.5)

A regional atmosphere model [Weather Research and Forecasting model version 3 (WRF3)] and a land surface model [Community Land Model, version 3.5 (CLM3.5)] were coupled to study the interactions between the atmosphere and possible future California land-cover changes. The impact was evaluated on California's climate of changes in natural vegetation under climate change and of intentional afforestation. The ability of WRF3 to simulate California's climate was assessed by comparing simulations by WRF3-CLM3.5 and WRF3-Noah to observations from 1982 to 1991. Using WRF3-CLM3.5, the authors performed six 13-yr experiments using historical and future large-scale climate boundary conditions from the Geophysical Fluid Dynamics Laboratory Climate Model version 2.1 (GFDL CM2.1). The land-cover scenarios included historical and future natural vegetation from the Mapped Atmosphere-Plant-Soil System-Century 1 (MC1) dynamic vegetation model, in addition to a future 8-million-ha California afforestation scenario. Natural vegetation changes alone caused summer daily-mean 2-m air temperature changes of -0.7 to +1 C in regions without persistent snow cover, depending on the location and the type of vegetation change. Vegetation temperature changes were much larger than the 2-m air temperature changes because of the finescale spatial heterogeneity of the imposed vegetation change. Up to 30% of the magnitude of the summer …
Date: November 1, 2010
Creator: Subin, Z. M.; Riley, W. J.; Kueppers, L. M.; Jin, J.; Christianson, D. S. & Torn, M. S.
Object Type: Article
System: The UNT Digital Library
A Distance Measure Comparison to Improve Crowding in Multi-Modal Problems. (open access)

A Distance Measure Comparison to Improve Crowding in Multi-Modal Problems.

Solving multi-modal optimization problems are of interest to researchers solving real world problems in areas such as control systems and power engineering tasks. Extensions of simple Genetic Algorithms, particularly types of crowding, have been developed to help solve these types of problems. This paper examines the performance of two distance measures, Mahalanobis and Euclidean, exercised in the processing of two different crowding type implementations against five minimization functions. Within the context of the experiments, empirical evidence shows that the statistical based Mahalanobis distance measure when used in Deterministic Crowding produces equivalent results to a Euclidean measure. In the case of Restricted Tournament selection, use of Mahalanobis found on average 40% more of the global optimum, maintained a 35% higher peak count and produced an average final best fitness value that is 3 times better.
Date: August 1, 2010
Creator: Vollmer, D. Todd; Soule, Terence & Manic, Milos
Object Type: Article
System: The UNT Digital Library
Metagenomic insights into evolution of heavy metal-contaminated groundwater microbial community (open access)

Metagenomic insights into evolution of heavy metal-contaminated groundwater microbial community

Understanding adaptation of biological communities to environmental change is a central issue in ecology and evolution. Metagenomic analysis of a stressed groundwater microbial community reveals that prolonged exposure to high concentrations of heavy metals, nitric acid and organic solvents ({approx}50 years) has resulted in a massive decrease in species and allelic diversity as well as a significant loss of metabolic diversity. Although the surviving microbial community possesses all metabolic pathways necessary for survival and growth in such an extreme environment, its structure is very simple, primarily composed of clonal denitrifying {gamma}- and {beta}-proteobacterial populations. The resulting community is overabundant in key genes conferring resistance to specific stresses including nitrate, heavy metals and acetone. Evolutionary analysis indicates that lateral gene transfer could have a key function in rapid response and adaptation to environmental contamination. The results presented in this study have important implications in understanding, assessing and predicting the impacts of human-induced activities on microbial communities ranging from human health to agriculture to environmental management, and their responses to environmental changes.
Date: July 1, 2010
Creator: Hemme, C. L.; Deng, Y.; Gentry, T. J.; Fields, M. W.; Wu, L.; Barua, S. et al.
Object Type: Article
System: The UNT Digital Library
Mapping swamp timothy (Cripsis schenoides) seed productivity using spectral values and vegetation indices in managed wetlands (open access)

Mapping swamp timothy (Cripsis schenoides) seed productivity using spectral values and vegetation indices in managed wetlands

This work examines the potential to predict the seed productivity of a key wetland plant species using spectral reflectance values and spectral vegetation indices. Specifically, the seed productivity of swamp timothy (Cripsis schenoides) was investigated in two wetland ponds, managed for waterfowl habitat, in California's San Joaquin Valley. Spectral reflectance values were obtained and associated spectral vegetation indices (SVI) calculated from two sets of high resolution aerial images (May 11, 2006 and June 9, 2006) and were compared to the collected vegetation data. Vegetation data were collected and analyzed from 156 plots for total aboveground biomass, total aboveground swamp timothy biomass, and total swamp timothy seed biomass. The SVI investigated included the Simple Ratio (SR), Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), Transformed Soil Adjusted Vegetation Index (TSAVI), Modified Soil Adjusted Vegetation Index (MSAVI), and Global Environment Monitoring Index (GEMI). We evaluated the correlation of the various SVI with in situ vegetation measurements for linear, quadratic, exponential and power functions. In all cases, the June image provided better predictive capacity relative to May, a result that underscores the importance of timing imagery to coincide with more favorable vegetation maturity. The north pond with the June image using …
Date: January 15, 2010
Creator: Rahilly, Patrick; Li, Donghai; Guo, Qinghua; Zhu, Jinxia; Ortega, Ricardo; Quinn, Nigel W. T. et al.
Object Type: Article
System: The UNT Digital Library
Overhead Detection of Underground Nuclear Explosions by Multi-Spectral and Infrared Imaging (open access)

Overhead Detection of Underground Nuclear Explosions by Multi-Spectral and Infrared Imaging

None
Date: September 10, 2010
Creator: Henderson, J. R.; Smith, M. O. & Zelinski, M. E.
Object Type: Report
System: The UNT Digital Library
Aircraft Field Exercise to Develop Multi-Spectral and Infrared Imaging for CTBT On-Site Inspections (open access)

Aircraft Field Exercise to Develop Multi-Spectral and Infrared Imaging for CTBT On-Site Inspections

None
Date: September 10, 2010
Creator: Henderson, J. R.; Smith, M. O. & Zelinski, M. E.
Object Type: Report
System: The UNT Digital Library
Interferometric adaptive optics for the National Ignition Facility (open access)

Interferometric adaptive optics for the National Ignition Facility

None
Date: January 14, 2010
Creator: Baker, K.; Homoelle, D.; Stappaerts, E.; Siders, C. & Barty, C.
Object Type: Article
System: The UNT Digital Library
Microwave Processing of Simulated Advanced Nuclear Fuel Pellets (open access)

Microwave Processing of Simulated Advanced Nuclear Fuel Pellets

Throughout the three-year project funded by the Department of Energy (DOE) and lead by Virginia Tech (VT), project tasks were modified by consensus to fit the changing needs of the DOE with respect to developing new inert matrix fuel processing techniques. The focus throughout the project was on the use of microwave energy to sinter fully stabilized zirconia pellets using microwave energy and to evaluate the effectiveness of techniques that were developed. Additionally, the research team was to propose fundamental concepts as to processing radioactive fuels based on the effectiveness of the microwave process in sintering the simulated matrix material.
Date: August 29, 2010
Creator: Clark, D. E. & Folz, D. C.
Object Type: Report
System: The UNT Digital Library
Magnetic ordering in tetragonal FeS: Evidence for strong itinerant spin fluctuations (open access)

Magnetic ordering in tetragonal FeS: Evidence for strong itinerant spin fluctuations

Mackinawite is a naturally occurring layer-type FeS mineral important in biogeochemical cycles and, more recently, in the development of microbial fuel cells. Conflicting results have been published as to the magnetic properties of this mineral, with Moessbauer spectroscopy indicating no magnetic ordering down to 4.2 K but density functional theory (DFT) predicting an antiferromagnetic ground state, similar to the Fe-based high-temperature superconductors with which it is isostructural and for which it is known that magnetism is suppressed by strong itinerant spin fluctuations. We investigated this latter possibility for mackinawite using photoemission spectroscopy, near-edge x-ray absorption fine structure spectroscopy, and DFT computations. Our Fe 3{sub s} core-level photoemission spectrum of mackinawite showed a clear exchange-energy splitting (2.9 eV) consistent with a 1 {micro}{sub B} magnetic moment on the Fe ions, while the Fe L-edge x-ray absorption spectrum indicated rather delocalized Fe 3{sub d} electrons in mackinawite similar to those in Fe metal. Our DFT computations demonstrated that the ground state of mackinawite is single-stripe antiferromagnetic, with an Fe magnetic moment (2.7 {micro}{sub B}) that is significantly larger than the experimental estimate and has a strong dependence on the S height and lattice parameters. All of these trends signal the existence of …
Date: November 1, 2010
Creator: Kwon, Kideok D.; Refson, Keith; Bone, Sharon; Qiao, Ruimin; Yang, Wan-li; Liu, Zhi et al.
Object Type: Article
System: The UNT Digital Library
Mechanisms of nickel sorption by a bacteriogenic birnessite (open access)

Mechanisms of nickel sorption by a bacteriogenic birnessite

A synergistic experimental-computational approach was used to study the molecular-scale mechanisms of Ni sorption at varying loadings and at pH 6-8 on the biogenic hexagonal birnessite produced by Pseudomonas putida GB-1. We found that Ni is scavenged effectively by bacterial biomass-birnessite assemblages. At surface excess values below 0.18 mol Ni kg{sup -1} sorbent (0.13 mol Ni mol{sup -1} Mn), the biomass component of the sorbent did not interfere with Ni sorption on mineral sites. Extended X-ray absorption fine structure (EXAFS) spectra showed two dominant coordination environments: Ni bound as a triple-corner-sharing (Ni-TCS) complex at vacancy sites and Ni incorporated (Ni-inc) into the MnO{sub 2} sheet, with the latter form of Ni favored at high sorptive concentrations and decreased proton activity. In parallel to our spectral analysis, first-principles geometry optimizations based on density functional theory (DFT) were performed to investigate the structure of Ni surface complexes at vacancy sites. Excellent agreement was achieved between EXAFS- and DFT-derived structural parameters for Ni-TCS and Ni-inc. Reaction-path calculations revealed a pH-dependent energy barrier associated with the transition from Ni-TCS to Ni-inc. Our results are consistent with the rate-limited incorporation of Ni at vacancy sites in our sorption samples, but near-equilibrium state of Ni in …
Date: April 1, 2010
Creator: Pena, Jasquelin; Kwon, Kideok D.; Refson, Keith; Bargar, John R. & Sposito, Garrison
Object Type: Article
System: The UNT Digital Library
Challenges, uncertainties and issues facing gas production from gas hydrate deposits (open access)

Challenges, uncertainties and issues facing gas production from gas hydrate deposits

The current paper complements the Moridis et al. (2009) review of the status of the effort toward commercial gas production from hydrates. We aim to describe the concept of the gas hydrate petroleum system, to discuss advances, requirement and suggested practices in gas hydrate (GH) prospecting and GH deposit characterization, and to review the associated technical, economic and environmental challenges and uncertainties, including: the accurate assessment of producible fractions of the GH resource, the development of methodologies for identifying suitable production targets, the sampling of hydrate-bearing sediments and sample analysis, the analysis and interpretation of geophysical surveys of GH reservoirs, well testing methods and interpretation of the results, geomechanical and reservoir/well stability concerns, well design, operation and installation, field operations and extending production beyond sand-dominated GH reservoirs, monitoring production and geomechanical stability, laboratory investigations, fundamental knowledge of hydrate behavior, the economics of commercial gas production from hydrates, and the associated environmental concerns.
Date: November 1, 2010
Creator: Moridis, G. J.; Collett, T. S.; Pooladi-Darvish, M.; Hancock, S.; Santamarina, C.; Boswell, R. et al.
Object Type: Article
System: The UNT Digital Library
Fission prompt gamma-ray multiplicity distribution measurements and simulations at DANCE (open access)

Fission prompt gamma-ray multiplicity distribution measurements and simulations at DANCE

The nearly energy independence of the DANCE efficiency and multiplicity response to {gamma} rays makes it possible to measure the prompt {gamma}-ray multiplicity distribution in fission. We demonstrate this unique capability of DANCE through the comparison of {gamma}-ray energy and multiplicity distribution between the measurement and numerical simulation for three radioactive sources {sup 22}Na, {sup 60}Co, and {sup 88}Y. The prospect for measuring the {gamma}-ray multiplicity distribution for both spontaneous and neutron-induced fission is discussed.
Date: August 24, 2010
Creator: Chyzh, A.; Wu, C. Y.; Ullmann, J.; Jandel, M.; Bredeweg, T.; Couture, A. et al.
Object Type: Report
System: The UNT Digital Library
Compact fission counter for DANCE (open access)

Compact fission counter for DANCE

The Detector for Advanced Neutron Capture Experiments (DANCE) consists of 160 BF{sub 2} crystals with equal solid-angle coverage. DANCE is a 4{pi} {gamma}-ray calorimeter and designed to study the neutron-capture reactions on small quantities of radioactive and rare stable nuclei. These reactions are important for the radiochemistry applications and modeling the element production in stars. The recognition of capture event is made by the summed {gamma}-ray energy which is equivalent of the reaction Q-value and unique for a given capture reaction. For a selective group of actinides, where the neutron-induced fission reaction competes favorably with the neutron capture reaction, additional signature is needed to distinguish between fission and capture {gamma} rays for the DANCE measurement. This can be accomplished by introducing a detector system to tag fission fragments and thus establish a unique signature for the fission event. Once this system is implemented, one has the opportunity to study not only the capture but also fission reactions. A parallel-plate avalanche counter (PPAC) has many advantages for the detection of heavy charged particles such as fission fragments. These include fast timing, resistance to radiation damage, and tolerance of high counting rate. A PPAC also can be tuned to be insensitive to …
Date: November 6, 2010
Creator: Wu, C. Y.; Chyzh, A.; Kwan, E.; Henderson, R.; Gostic, J.; Carter, D. et al.
Object Type: Report
System: The UNT Digital Library
Unfolding the fission prompt gamma-ray energy and multiplicity distribution measured by DANCE (open access)

Unfolding the fission prompt gamma-ray energy and multiplicity distribution measured by DANCE

The nearly energy independence of the {gamma}-ray efficiency and multiplicity response for the DANCE array, the unusual characteristic elucidated in our early technical report (LLNL-TR-452298), gives one a unique opportunity to derive the true prompt {gamma}-ray energy and multiplicity distribution in fission from the measurement. This unfolding procedure for the experimental data will be described in details and examples will be given to demonstrate the feasibility of reconstruction of the true distribution.
Date: October 16, 2010
Creator: Chyzh, A.; Wu, C. Y.; Bredeweg, T.; Couture, A.; Jandel, M.; Ullmann, J. et al.
Object Type: Report
System: The UNT Digital Library