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Latest nH analysis in the Double Chooz experiment  [PDF]
Guang Yang
Physics , 2015,
Abstract: Precise measurement of the neutrino mixing angle $\theta_{13}$ is the primary goal of the Double Chooz Experiment (DC), which is located in Chooz, France. The inverse beta decay process provides a unique signature of reactor anti-neutrino interactions, giving prompt signals from positron annihilation and delayed signals from neutron capture by either Gadolinium (Gd) or Hydrogen (H). This paper is dedicated to the latest nH analysis in Double Chooz. Typically, The Gd analysis is primary since fewer background events are involved. However, with accurate estimates of backgrounds and a precise reconstruction of energy, the nH analysis gives a powerful independent measurement of $\theta_{13}$.
Muon capture on light isotopes in Double Chooz  [PDF]
Double Chooz collaboration,Y. Abe,T. Abrah?o,H. Almazan,C. Alt,S. Appel,J. C. Barriere,E. Baussan,I. Bekman,M. Bergevin,T. J. C. Bezerra,L. Bezrukov,E. Blucher,T. Brugière,C. Buck,J. Busenitz,A. Cabrera,L. Camilleri,R. Carr,M. Cerrada,E. Chauveau,P. Chimenti,A. P. Collin,E. Conover,J. M. Conrad,J. I. Crespo-Anadón,K. Crum,A. S. Cucoanes,E. Damon,J. V. Dawson,H. de Kerret,J. Dhooghe,D. Dietrich,Z. Djurcic,J. C. dos Anjos,M. Dracos,A. Etenko,M. Fallot,J. Felde,S. M. Fernandes,V. Fischer,D. Franco,M. Franke,H. Furuta,I. Gil-Botella,L. Giot,M. G?ger-Neff,H. Gomez,L. F. G. Gonzalez,L. Goodenough,M. C. Goodman,N. Haag,T. Hara,J. Haser,D. Hellwig,M. Hofmann,G. A. Horton-Smith,A. Hourlier,M. Ishitsuka,J. Jochum,C. Jollet,F. Kaether,L. N. Kalousis,Y. Kamyshkov,M. Kaneda,D. M. Kaplan,T. Kawasaki,E. Kemp,D. Kryn,M. Kuze,T. Lachenmaier,C. E. Lane,T. Lasserre,A. Letourneau,D. Lhuillier,H. P. Lima Jr,M. Lindner,J. M. López-Casta?o,J. M. LoSecco,B. Lubsandorzhiev,S. Lucht,J. Maeda,C. Mariani,J. Maricic,J. Martino,T. Matsubara,G. Mention,A. Meregaglia,T. Miletic,R. Milincic,A. Minotti,Y. Nagasaka,D. Navas-Nicolás,P. Novella,L. Oberauer,M. Obolensky,A. Onillon,A. Osborn,C. Palomares,I. M. Pepe,S. Perasso,A. Porta,G. Pronost,J. Reichenbacher,B. Reinhold,M. R?hling,R. Roncin,B. Rybolt,Y. Sakamoto,R. Santorelli,A. C. Schilithz,S. Sch?nert,S. Schoppmann,M. H. Shaevitz,R. Sharankova,D. Shrestha,V. Sibille,V. Sinev,M. Skorokhvatov,E. Smith,M. Soiron,J. Spitz,A. Stahl,I. Stancu,L. F. F. Stokes
Physics , 2015,
Abstract: Using the Double Chooz detector, designed to measure the neutrino mixing angle $\theta_{13}$, the products of $\mu^-$ capture on $^{12}$C, $^{13}$C, $^{14}$N and $^{16}$O have been measured. Over a period of 489.5 days, $2.3\times10^6$ stopping cosmic $\mu^-$ have been collected, of which $1.8\times10^5$ captured on carbon, nitrogen, or oxygen nuclei in the inner detector scintillator or acrylic vessels. The resulting isotopes were tagged using prompt neutron emission (when applicable), the subsequent beta decays, and, in some cases, $\beta$-delayed neutrons. The most precise measurement of the rate of $^{12}\mathrm C(\mu^-,\nu)^{12}\mathrm B$ to date is reported: $6.57^{+0.11}_{-0.21}\times10^{3}\,\mathrm s^{-1}$, or $(17.35^{+0.35}_{-0.59})\%$ of nuclear captures. By tagging excited states emitting gammas, the ground state transition rate to $^{12}$B has been determined to be $5.68^{+0.14}_{-0.23}\times10^3\,\mathrm s^{-1}$. The heretofore unobserved reactions $^{12}\mathrm C(\mu^-,\nu\alpha)^{8}\mathrm{Li}$, $^{13}\mathrm C(\mu^-,\nu\mathrm n\alpha)^{8}\mathrm{Li}$, and $^{13}\mathrm C(\mu^-,\nu\mathrm n)^{12}\mathrm B$ are measured. Further, a population of $\beta$n decays following stopping muons is identified with $5.5\sigma$ significance. Statistics limit our ability to identify these decays definitively. Assuming negligible production of $^{8}$He, the reaction $^{13}\mathrm C(\mu^-,\nu\alpha)^{9}\mathrm{Li}$ is found to be present at the $2.7\sigma$ level. Limits are set on a variety of other processes.
Measurement of $θ_{13}$ in Double Chooz using neutron captures on hydrogen with novel background rejection techniques  [PDF]
Double Chooz Collaboration,Y. Abe,T. Abrah?o,H. Almazan,C. Alt,J. C. dos Anjos,J. C. Barriere,E. Baussan,I. Bekman,M. Bergevin,T. J. C. Bezerra,L. Bezrukov,E. Blucher,T. Brugière,C. Buck,J. Busenitz,A. Cabrera,L. Camilleri,R. Carr,M. Cerrada,E. Chauveau,P. Chimenti,A. P. Collin,J. M. Conrad,J. I. Crespo-Anadón,K. Crum,A. S. Cucoanes,E. Damon,J. V. Dawson,J. Dhooghe,D. Dietrich,Z. Djurcic,M. Dracos,A. Etenko,M. Fallot,F. von Feilitzsch,J. Felde,S. M. Fernandes,V. Fischer,D. Franco,M. Franke,H. Furuta,I. Gil-Botella,L. Giot,M. G?ger-Neff,H. Gomez,L. F. G. Gonzalez,L. Goodenough,M. C. Goodman,N. Haag,T. Hara,J. Haser,D. Hellwig,M. Hofmann,G. A. Horton-Smith,A. Hourlier,M. Ishitsuka,J. Jochum,C. Jollet,F. Kaether,L. N. Kalousis,Y. Kamyshkov,M. Kaneda,D. M. Kaplan,T. Kawasaki,E. Kemp,H. de Kerret,D. Kryn,M. Kuze,T. Lachenmaier,C. E. Lane,T. Lasserre,A. Letourneau,D. Lhuillier,H. P. Lima Jr,M. Lindner,J. M. López-Casta?o,J. M. LoSecco,B. Lubsandorzhiev,S. Lucht,J. Maeda,C. Mariani,J. Maricic,J. Martino,T. Matsubara,G. Mention,A. Meregaglia,T. Miletic,R. Milincic,A. Minotti,Y. Nagasaka,D. Navas-Nicolás,P. Novella,L. Oberauer,M. Obolensky,A. Onillon,A. Osborn,C. Palomares,I. M. Pepe,S. Perasso,A. Porta,G. Pronost,J. Reichenbacher,B. Reinhold,M. R?hling,R. Roncin,B. Rybolt,Y. Sakamoto,R. Santorelli,A. C. Schilithz,S. Sch?nert,S. Schoppmann,M. H. Shaevitz,R. Sharankova,D. Shrestha,V. Sibille,V. Sinev,M. Skorokhvatov,E. Smith,M. Soiron,J. Spitz,A. Stahl,I. Stancu,L. F. F. Stokes
Physics , 2015,
Abstract: 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).
The Double Chooz Experiment  [PDF]
Charles E. Lane
Physics , 2008,
Abstract: The Double Chooz experiment returns to the site of the Chooz experiment with a pair of detectors for a differential neutrino flux measurement, providing sensitivity to sin^2(2theta13) > 0.03. Reaching this goal requires significant improvements in systematic uncertainties, based on the experience with previous reactor neutrino experiments.
The Double Chooz Experiment  [PDF]
Daniel M. Kaplan
Physics , 2006, DOI: 10.1063/1.2402699
Abstract: There is broad consensus in the worldwide physics community as to the need for a new reactor-neutrino experiment to measure or limit the neutrino mixing angle $\theta_{13}$. The Double Chooz Experiment, planned for operation in the years 2008-2011, will search for values of $\sin^2{2\theta_{13}}$ down to $\approx$0.03. This will be the first new information on $\theta_{13}$ in over a decade and will cover most of the remaining parameter space. A quick and relatively inexpensive project is made possible by the existing neutrino laboratory at the Chooz site.
Status of the Double Chooz Experiment  [PDF]
J. V. Dawson
Physics , 2009,
Abstract: The Double Chooz experiment is the first of the next wave of reactor experiments searching for a non-vanishing value of the mixing angle theta_13. The experimental concept and detector design are presented, and the most pertinent backgrounds are discussed. Operation of the far detector is expected to begin by the end of 2009. Installation of the near detector will occur in 2010. Double Chooz has the capacity to measure sin^2(2theta_13) to 3 sigma if sin^2(2theta_13) >0.05 or exclude sin^2 (2theta_13) down to 0.03 at 90% for Delta m_31^2 = 2.5 x 10^-3 eV^2 with three years of data with both near and far detectors.
Ortho-positronium observation in the Double Chooz Experiment  [PDF]
Y. Abe,J. C. dos Anjos,J. C. Barriere,E. Baussan,I. Bekman,M. Bergevin,T. J. C. Bezerra,L. Bezrukov,E. Blucher,C. Buck,J. Busenitz,A. Cabrera,E. Caden,L. Camilleri,R. Carr,M. Cerrada,P. -J. Chang,E. Chauveau,P. Chimenti,A. P. Collin,E. Conover,J. M. Conrad,J. I. Crespo-Anadon,K. Crum,A. S. Cucoanes,E. Damon,J. V. Dawson,J. Dhooghe,D. Dietrich,Z. Djurcic,M. Dracos,M. Elnimr,A. Etenko,M. Fallot,F. von Feilitzsch,J. Felde,S. M. Fernandes,V. Fischer,D. Franco,M. Franke,H. Furuta,I. Gil-Botella,L. Giot,M. Goger-Neff,L. F. G. Gonzalez,L. Goodenough,M. C. Goodman,C. Grant,N. Haag,T. Hara,J. Haser,M. Hofmann,G. A. Horton-Smith,A. Hourlier,M. Ishitsuka,J. Jochum,C. Jollet,F. Kaether,L. N. Kalousis,Y. Kamyshkov,D. M. Kaplan,T. Kawasaki,E. Kemp,H. de Kerret,D. Kryn,M. Kuze,T. Lachenmaier,C. E. Lane,T. Lasserre,A. Letourneau,D. Lhuillier,H. P. Lima Jr,M. Lindner,J. M. Lopez-Castano,J. M. LoSecco,B. Lubsandorzhiev,S. Lucht,J. Maeda,C. Mariani,J. Maricic,J. Martino,T. Matsubara,G. Mention,A. Meregaglia,T. Miletic,R. Milincic,A. Minotti,Y. Nagasaka,Y. Nikitenko,P. Novella,L. Oberauer,M. Obolensky,A. Onillon,A. Osborn,C. Palomares,I. M. Pepe,S. Perasso,P. Pfahler,A. Porta,G. Pronost,J. Reichenbacher,B. Reinhold,M. Rohling,R. Roncin,S. Roth,B. Rybolt,Y. Sakamoto,R. Santorelli,A. C. Schilithz,S. Schonert,S. Schoppmann,M. H. Shaevitz,R. Sharankova,S. Shimojima,D. Shrestha,V. Sibille,V. Sinev,M. Skorokhvatov,E. Smith,J. Spitz,A. Stahl,I. Stancu,L. F. F. Stokes,M. Strait,A. Stuken,F. Suekane
Statistics , 2014, DOI: 10.1007/JHEP10(2014)032
Abstract: The Double Chooz experiment measures the neutrino mixing angle $\theta_{13}$ by detecting reactor $\bar{\nu}_e$ via inverse beta decay. The positron-neutron space and time coincidence allows for a sizable background rejection, nonetheless liquid scintillator detectors would profit from a positron/electron discrimination, if feasible in large detector, to suppress the remaining background. Standard particle identification, based on particle dependent time profile of photon emission in liquid scintillator, can not be used given the identical mass of the two particles. However, the positron annihilation is sometimes delayed by the ortho-positronium (o-Ps) metastable state formation, which induces a pulse shape distortion that could be used for positron identification. In this paper we report on the first observation of positronium formation in a large liquid scintillator detector based on pulse shape analysis of single events. The o-Ps formation fraction and its lifetime were measured, finding the values of 44$\%$ $\pm$ 12$\%$ (sys.) $\pm$ 5$\%$ (stat.) and $3.68$ns $\pm$ 0.17ns (sys.) $\pm$ 0.15ns (stat.) respectively, in agreement with the results obtained with a dedicated positron annihilation lifetime spectroscopy setup.
Double-Chooz Neutrino Experiment  [PDF]
C. Palomares
Physics , 2009,
Abstract: The Double Chooz experiment will use the electron antineutrinos produced by the Chooz nuclear power station to search for a non-vanishing value of the Theta_13 neutrino mixing angle. Double Chooz will be the first of a new generation of neutrino experiments using identical detectors at different distances from the neutrino source to reduce the systematic errors due to the uncertainties on the neutrino flux and to the detector acceptance. The far detector is expected to be operative by the beginning of 2010. Installation of the near detector will occur in 2010.
The Double Chooz reactor neutrino experiment  [PDF]
I. Gil-Botella
Physics , 2007, DOI: 10.1088/1742-6596/110/8/082007
Abstract: The Double Chooz reactor neutrino experiment will be the next detector to search for a non vanishing theta13 mixing angle with unprecedented sensitivity, which might open the way to unveiling CP violation in the leptonic sector. The measurement of this angle will be based in a precise comparison of the antineutrino spectrum at two identical detectors located at different distances from the Chooz nuclear reactor cores in France. Double Chooz is particularly attractive because of its capability to measure sin2(2theta13) to 3 sigmas if sin2(2theta13) > 0.05 or to exclude sin2(2theta13) down to 0.03 at 90% C.L. for Dm2 = 2.5 x 10-3 eV2 in three years of data taking with both detectors. The construction of the far detector starts in 2008 and the first neutrino results are expected in 2009. The current status of the experiment, its physics potential and design and expected performance of the detector are reviewed.
The Trigger and Timing System of the Double Chooz Experiment  [PDF]
F. Beissel,A. Cabrera,A. Cucuanes,J. V. Dawson,D. Kryn,C. Kuhnt,S. Lucht,B. Reinhold,M. Rosenthal,S. Roth,A. Stahl,A. Stüken,C. Wiebusch
Physics , 2012, DOI: 10.1088/1748-0221/8/01/T01003
Abstract: Modern precision neutrino experiments like Double Chooz require a highly efficient trigger system in order to reduce systematic uncertainties. The trigger and timing system of the Double Chooz experiment was designed according to this goal. The Double Chooz trigger system is driven by the basic idea of triggering on multiple thresholds according to the total visible energy and additionally triggering on the number of active photomultiplier tubes (PMTs) in the detector. To do so, the trigger system continuously monitors the analogue signals from all PMTs in the detector. The amplitudes of these PMT-signals are summed for groups of certain PMTs (group signals) and for all PMTs (sum signal), respectively. The group signals are discriminated by two thresholds for each input channel and four thresholds for the sum signal. The resulting signals are processed by the trigger logic unit which is implemented in a FPGA. In addition to the proper trigger, the trigger system provides a common clock signal for all subsequent data acquisition systems to guarantee a synchronous readout of the Double Chooz detectors. The present design of the system provides a high flexibility for the applied logic and settings, making it useful for experiments other than Double Chooz. The Double Chooz trigger and timing system was installed and commissioned in 2011. This article describes the hardware of the trigger and timing system. Furthermore the setup, implemented trigger logic and performance of the trigger and timing system for the Double Chooz experiment is presented.
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