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"Goodman, M C"
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The nature of electrostatic potential fluctuations in Cu2ZnSnS4 and their role on photovoltaic device performance
2013
Aberration corrected STEM EELS is used to investigate point defects in Cu2ZnSnS4 (CZTS). Nano-scale clusters of ZnCu anti-site donors are observed with the donor concentration being sufficiently high to degenerately dope the semiconductor. Uncompensated donors and acceptors result in electrostatic potential fluctuations within the material. The effect of these potential fluctuations on the photovoltaic device properties is discussed.
Journal Article
Improved measurements of the neutrino mixing angle θ13 with the Double Chooz detector
by
Dracos, M.
,
Furuta, H.
,
Shimojima, S.
in
Classical and Quantum Gravitation
,
Elementary Particles
,
INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
2014
A
bstract
The Double Chooz experiment presents improved measurements of the neutrino mixing angle
θ
13
using the data collected in 467.90 live days from a detector positioned at an average distance of 1050 m from two reactor cores at the Chooz nuclear power plant. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties with respect to previous publications, whereas the efficiency of the
ν
¯
e
signal has increased. The value of
θ
13
is measured to be sin
2
2
θ
13
= 0.090
− 0.029
+ 0.032
from a fit to the observed energy spectrum. Deviations from the reactor
ν
¯
e
prediction observed above a prompt signal energy of 4 MeV and possible explanations are also reported. A consistent value of
θ
13
is obtained from a fit to the observed rate as a function of the reactor power independently of the spectrum shape and background estimation, demonstrating the robustness of the
θ
13
measurement despite the observed distortion.
Journal Article
Model for Mammalian Metallothionein Structure
by
Forte, Carla P.
,
Fesik, Stephen W.
,
Armitage, Ian M.
in
Amino Acid Sequence
,
Amino acids
,
Base Sequence
1983
The results of physicochemical studies of mammalian metallothioneins are summarized and used to propose a model of the protein. The primary structures of all mammalian metallothioneins are very homologous; there are 38 invariant residues and 20 of them are cysteines. The results of UV and CD optical studies indicated that all 20 cysteines are involved in the ligation of 7 mol of metal per mol of metallothionein and that the protein does not contain any α -helix structure. A theoretical analysis by the Chou-Fasman method has predicted 11 β -bends, each one involving at least one cysteine residue. The most significant structural data, provided by113Cd NMR, demonstrated that the 7 mol of bound Cd2+are arranged in two separate metal clusters, one containing four metal ions and the other containing three, with all Cd2+tetrahedrally coordinated to cysteine thiolate ligands. The 11 cysteine residues of the carboxyl-terminal portion of the metallothionein chain (residues 30-61) are ligated to the 4-metal cluster as shown by113Cd NMR of this enzymatically cleaved fragment. The remaining cysteine residues from the amino-terminal polypeptide portion (residues 1-29) form the 3-metal cluster. Such a division of the chain is consistent with the presence of an intron in the mouse metallothionein-1 gene corresponding to residue 32 in the polypeptide chain. A two-domain molecular model has been constructed based on an analysis of all the available data and is described in detail. The accuracy of this model was tested by1H NMR at 500 MHz and the data are in agreement with our proposed structure.
Journal Article
Reactor Rate Modulation oscillation analysis with two detectors in Double Chooz
2020
A \\(\\theta_{13}\\) oscillation analysis based on the observed antineutrino rates at the Double Chooz far and near detectors for different reactor power conditions is presented. This approach provides a so far unique simultaneous determination of \\(\\theta_{13}\\) and the total background rates without relying on any assumptions on the specific background contributions. The analysis comprises 865 days of data collected in both detectors with at least one reactor in operation. The oscillation results are enhanced by the use of 24.06 days (12.74 days) of reactor-off data in the far (near) detector. The analysis considers the \\nue interactions up to a visible energy of 8.5 MeV, using the events at higher energies to build a cosmogenic background model considering fast-neutrons interactions and \\(^{9}\\)Li decays. The background-model-independent determination of the mixing angle yields sin\\(^2(2\\theta_{13})=0.094\\pm0.017\\), being the best-fit total background rates fully consistent with the cosmogenic background model. A second oscillation analysis is also performed constraining the total background rates to the cosmogenic background estimates. While the central value is not significantly modified due to the consistency between the reactor-off data and the background estimates, the addition of the background model reduces the uncertainty on \\(\\theta_{13}\\) to 0.015. Along with the oscillation results, the normalization of the anti-neutrino rate is measured with a precision of 0.86\\%, reducing the 1.43\\% uncertainty associated to the expectation.
Measurement of θ 13 in Double Chooz using neutron captures on hydrogen with novel background rejection techniques
by
Dracos, M.
,
Furuta, H.
,
Jochum, J.
in
electroweak interaction
,
flavor physics
,
neutrino detectors and telescopes
2016
We observed a measurement of the Double Chooz collaboration and the neutrino mixing angle θ13 using reactor $\\bar{v}$e via the inverse beta decay reaction in which the neutron is captured on hydrogen. Our measurement is based on 462.72 live days data, approximately twice as much data as in the previous such analysis, collected with a detector positioned at an average distance of 1050 m from two reactor cores. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties. Accidental coincidences, the dominant background in this analysis, are suppressed by more than an order of magnitude with respect to our previous publication by a multi-variate analysis. Furthermore, these improvements demonstrate the capability of precise measurement of reactor $\\bar{v}$e without gadolinium loading. Spectral distortions from the $\\bar{v}$e reactor flux predictions previously reported with the neutron capture on gadolinium events are confirmed in the independent data sample presented here. A value of sin2 2θ13= 0.0950.039+0.038 (stat+syst) is obtained from a fit to the observed event rate as a function of the reactor power, a method insensitive to the energy spectrum shape. A simultaneous fit of the hydrogen capture events and of the gadolinium capture events yields a measurement of sin2 2θ13 = 0.088 ± 0.033(stat+syst).
Journal Article
Measurement of $\\theta_{13}$ in Double Chooz using neutron captures on hydrogen with novel background rejection techniques
2016
The Double Chooz collaboration presents a measurement of the neutrino mixing angle $\\theta_{13}$ using reactor $\\overline{\\nu}_{e}$ observed via the inverse beta decay reaction in which the neutron is captured on hydrogen. This measurement is based on 462.72 live days data, approximately twice as much data as in the previous such analysis, collected with a detector positioned at an average distance of 1050m from two reactor cores. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties. Accidental coincidences, the dominant background in this analysis, are suppressed by more than an order of magnitude with respect to our previous publication by a multi-variate analysis. These improvements demonstrate the capability of precise measurement of reactor $\\overline{\\nu}_{e}$ without gadolinium loading. Spectral distortions from the $\\overline{\\nu}_{e}$ reactor flux predictions previously reported with the neutron capture on gadolinium events are confirmed in the independent data sample presented here. A value of $\\sin^{2}2\\theta_{13} = 0.095^{+0.038}_{-0.039}$(stat+syst) is obtained from a fit to the observed event rate as a function of the reactor power, a method insensitive to the energy spectrum shape. A simultaneous fit of the hydrogen capture events and of the gadolinium capture events yields a measurement of $\\sin^{2}2\\theta_{13} = 0.088\\pm0.033$(stat+syst).
Journal Article
Design and performance of a 35-ton liquid argon time projection chamber as a prototype for future very large detectors
2020
Liquid argon time projection chamber technology is an attractive choice for large neutrino detectors, as it provides a high-resolution active target and it is expected to be scalable to very large masses. Consequently, it has been chosen as the technology for the first module of the DUNE far detector. However, the fiducial mass required for \"far detectors\" of the next generation of neutrino oscillation experiments far exceeds what has been demonstrated so far. Scaling to this larger mass, as well as the requirement for underground construction places a number of additional constraints on the design. A prototype 35-ton cryostat was built at Fermi National Acccelerator Laboratory to test the functionality of the components foreseen to be used in a very large far detector. The Phase I run, completed in early 2014, demonstrated that liquid argon could be maintained at sufficient purity in a membrane cryostat. A time projection chamber was installed for the Phase II run, which collected data in February and March of 2016. The Phase II run was a test of the modular anode plane assemblies with wrapped wires, cold readout electronics, and integrated photon detection systems. While the details of the design do not match exactly those chosen for the DUNE far detector, the 35-ton TPC prototype is a demonstration of the functionality of the basic components. Measurements are performed using the Phase II data to extract signal and noise characteristics and to align the detector components. A measurement of the electron lifetime is presented, and a novel technique for measuring a track's position based on pulse properties is described.
Improved measurements of the neutrino mixing angle θ 13 with the Double Chooz detector
2014
The Double Chooz experiment presents improved measurements of the neutrino mixing angle θ13 using the data collected in 467.90 live days from a detector positioned at an average distance of 1050 m from two reactor cores at the Chooz nuclear power plant. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties with respect to previous publications, whereas the efficiency of the ν¯e signal has increased. The value of θ13 is measured to be sin22θ13=0.090+0.032-0.029 from a fit to the observed energy spectrum. Deviations from the reactor ν¯e prediction observed above a prompt signal energy of 4 MeV and possible explanations are also reported. A consistent value of θ13 is obtained from a fit to the observed rate as a function of the reactor power independently of the spectrum shape and background estimation, demonstrating the robustness of the θ13 measurement despite the observed distortion.
Journal Article