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Articles de revues sur le sujet « Single beta decay »

Auteur : Grafiati
Publié le 9 mars 2023
Mis à jour le 10 mars 2023

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1

Díaz, Jorge S. « Tests of Lorentz Symmetry in Single Beta Decay ». Advances in High Energy Physics 2014 (2014) : 1–7. http://dx.doi.org/10.1155/2014/305298.

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Low-energy experiments studying single beta decay can serve as sensitive probes of Lorentz invariance that can complement interferometric searches for deviations from this spacetime symmetry. Experimental signatures of a dimension-three operator for Lorentz violation which are unobservable in neutrino oscillations are described for the decay of polarized and unpolarized neutrons as well as for measurements of the spectral endpoint in beta decay.
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2

Krmpotić, F., J. Hirsch et H. Dias. « Double-beta decay within a single-mode model ». Nuclear Physics A 542, no 1 (juin 1992) : 85–96. http://dx.doi.org/10.1016/0375-9474(92)90398-4.

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3

Kohyama, Y., K. Kubodera et K. Yazaki. « Comment on neutrinoless double-beta decay between pairs of single-beta emitters ». Physics Letters B 168, no 1-2 (février 1986) : 21–25. http://dx.doi.org/10.1016/0370-2693(86)91452-8.

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4

MATSUDA, KOICHI, TATSURU KIKUCHI, TAKESHI FUKUYAMA et HIROYUKI NISHIURA. « CONSTRAINTS FROM NEUTRINOLESS DOUBLE BETA DECAY ». Modern Physics Letters A 17, no 39 (21 décembre 2002) : 2597–603. http://dx.doi.org/10.1142/s0217732302009362.

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We examine the constraints from the recent HEIDELBERG–MOSCOW double beta decay experiment. It leads us to the almost degenerate or inverse hierarchy neutrino mass scenario. In this scenario, we obtain possible upper bounds for the Majorana CP violating phase in the lepton sector by incorporating the data from the neutrino oscillation, the single beta decay experiments, and from the astrophysical observation. We also predict the neutrino mass that may be measurable in the future beta decay experiments.
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5

Borzov, I. N. « Evolution of single-particle structure and beta-decay near78Ni ». EPJ Web of Conferences 38 (2012) : 12002. http://dx.doi.org/10.1051/epjconf/20123812002.

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6

Skalsey, M. « Feasibility of detecting neutrinoless double-beta decay between pairs of single-beta emitters ». Physical Review C 36, no 2 (1 août 1987) : 820–21. http://dx.doi.org/10.1103/physrevc.36.820.

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7

Severyukhin, A. P., N. N. Arsenyev, I. N. Borzov, R. G. Nazmitdinov et S. Åberg. « Two-phonon structures for beta-decay theory ». EPJ Web of Conferences 194 (2018) : 02008. http://dx.doi.org/10.1051/epjconf/201819402008.

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The β-decay rates of 60Ca have been studied within a microscopic model, which is based on the Skyrme interaction T45 to construct single-particle and phonon spaces. We observe a redistribution of the Gamow–Teller strength due to the phonon-phonon coupling, considered in the model. For 60Sc, the spin-parity of the ground state is found to be 1+. We predict that the half-life of 60Ca is 0.3 ms, while the total probability of the βxn emission is 6:1%. Additionally, the random matrix theory has been applied to analyze the statistical properties of the 1+ spectrum populated in the β-decay to elucidate the obtained results.
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8

Kohyama, Y., K. Kubodera et M. Takizawa. « Comment on ‘‘Feasibility of detecting neutrinoless double-beta decay between pairs of single-beta emitters’’ ». Physical Review C 37, no 4 (1 avril 1988) : 1778–79. http://dx.doi.org/10.1103/physrevc.37.1778.

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9

Lenske, Horst. « Heavy Ion Charge Exchange Reactions as Probes for Beta–Decay ». EPJ Web of Conferences 223 (2019) : 01031. http://dx.doi.org/10.1051/epjconf/201922301031.

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Peripheral heavy ion single and double charge reactions are described by fully quantum mechanical distorted wave methods. A special class of nuclear double charge exchange (DCE) reactions proceeding as a one-step reaction through a two-body process are shown to proceed by nuclear matrix elements of a diagrammatic structure as found also in 0ν2ß decay. These hadronic Majorana-type DCE reactions (MDCE) have to be distinguished from second order DCE reactions, given by double single charge exchange (DSCE) processes, resembling 2ν2ß decay. The theoretical concepts of MDCE are discussed. First results show that ion-ion DCE reactions are the ideal testing grounds for investigations of rare second order nuclear processes, giving insight into nuclear in-medium two-body correlation.
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10

Moreno, O., R. Álvarez-Rodríguez, P. Sarriguren, E. Moya de Guerra, F. Šimkovic et A. Faessler. « Single- and low-lying-states dominance in two-neutrino double-beta decay ». Journal of Physics G : Nuclear and Particle Physics 36, no 1 (31 octobre 2008) : 015106. http://dx.doi.org/10.1088/0954-3899/36/1/015106.

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11

Hirsch, Jorge G., Peter O. Hess et Osvaldo Civitarese. « Single- and double-beta decay Fermi transitions in an exactly solvable model ». Physical Review C 56, no 1 (1 juillet 1997) : 199–211. http://dx.doi.org/10.1103/physrevc.56.199.

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12

Aryal, P., A. Khan, H. J. Kim, P. Q. Vuong, J. Kaewkhao, S. Kothan et S. Kaewjaeng. « Development of Tin-Based Single Crystal Scintillator for Double-Beta Decay Experiments ». IEEE Transactions on Nuclear Science 67, no 6 (juin 2020) : 922–26. http://dx.doi.org/10.1109/tns.2020.2978903.

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13

Minakata, Hisakazu, et Hiroaki Sugiyama. « Lower bound on |Ue3|2 from single and double beta decay experiments ». Physics Letters B 526, no 3-4 (février 2002) : 335–44. http://dx.doi.org/10.1016/s0370-2693(01)01508-8.

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14

Auerbach, Naftali, et Minh-Loc Bui. « Study of the double Gamow-Teller transitions using the shell model approach ». EPJ Web of Conferences 194 (2018) : 02003. http://dx.doi.org/10.1051/epjconf/201819402003.

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The double Gamow-Teller strength distributions in the lightest double beta-decay candidate 48Ca and its isotope 46Ca were calculated using the nuclear shell model by applying the single Gamow-Teller operator two times sequentially on the ground state of parent nucleus. The nuclear matrix element of the double Gamow- Teller transition from the ground state to the ground state that goes into the double beta decay calculation was shown as a small fraction of the total transition.
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15

Skalsey, M. « Reply to ‘‘Comment on ‘Feasibility of detecting neutrinoless double-beta decay between pairs of single-beta emitters’ ’’ ». Physical Review C 37, no 4 (1 avril 1988) : 1780. http://dx.doi.org/10.1103/physrevc.37.1780.

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16

Khatun, Amina, Adam Smetana et Fedor Šimkovic. « Three Flavor Quasi-Dirac Neutrino Mixing, Oscillations and Neutrinoless Double Beta Decay ». Symmetry 12, no 8 (5 août 2020) : 1310. http://dx.doi.org/10.3390/sym12081310.

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The extension of the Standard model by three right-handed neutrino fields exhibit appealing symmetry between left-handed and right-handed sectors, which is only violated by interactions. It can accommodate three flavor quasi-Dirac neutrino mixing scheme, which allows processes with violation of both lepton flavor and total lepton number symmetries. We propose a 6×6 unitary matrix for parameterizing the mixing among three flavors of quasi-Dirac neutrino. This mixing matrix is constructed by two 3×3 unitary matrices that diagonalizes the Dirac mass term in the Lagrangian. By only assuming the Standard Model V−A weak interaction, it is found that probabilities of neutrino oscillations among active flavor states and effective masses measured by single beta decay, by neutrinoless double-beta decay and by cosmology only depend on single 3×3 unitary matrix relevant to mixing of active neutrino flavors. Further, by considering 1σ and 3σ uncertainties in the measured oscillation probability of electron antineutrino from reactor, derivation of the constraint on the Majorana neutrino mass component is demonstrated. The consequence for effective Majorana neutrino mass governing the neutrinoless double-beta decay is discussed.
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17

Simkovic, F., P. Domin et S. V. Semenov. « The single state dominance hypothesis and the two-neutrino double beta decay of100Mo ». Journal of Physics G : Nuclear and Particle Physics 27, no 11 (3 octobre 2001) : 2233–40. http://dx.doi.org/10.1088/0954-3899/27/11/304.

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18

Kotila, Jenni. « Role of Single-Particle Energies in Microscopic Interacting Boson Model Double Beta Decay Calculations ». Universe 7, no 3 (11 mars 2021) : 66. http://dx.doi.org/10.3390/universe7030066.

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Single-particle level energies form a significant input in nuclear physics calculations where single-particle degrees of freedom are taken into account, including microscopic interacting boson model investigations. The single-particle energies may be treated as input parameters that are fitted to reach an optimal fit to the data. Alternatively, they can be calculated using a mean field potential, or they can be extracted from available experimental data, as is done in the current study. The role of single-particle level energies in the microscopic interacting boson model calculations is discussed with special emphasis on recent double beta decay calculations.
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19

Ejiri, Hiroyasu. « Neutrino-Mass Sensitivity and Nuclear Matrix Element for Neutrinoless Double Beta Decay ». Universe 6, no 12 (27 novembre 2020) : 225. http://dx.doi.org/10.3390/universe6120225.

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Neutrinoless double beta decay (DBD) is a useful probe to study neutrino properties such as the Majorana nature, the absolute neutrino mass, the CP phase and the others, which are beyond the standard model. The nuclear matrix element (NME) for DBD is crucial to extract the neutrino properties from the experimental transition rate. The neutrino-mass sensitivity, i.e., the minimum neutrino-mass to be measured by the DBD experiment, is very sensitive to the DBD NME. Actually, the NME is one of the key elements for designing the DBD experiment. Theoretical evaluation for the DBD NME, however, is very hard. Recently experimental studies of charge-exchange nuclear and leptonic reactions have shown to be used to get single-β NMEs associated with the DBD NME. Critical discussions are made on the neutrino-mass sensitivity and the NME for the DBD neutrino-mass study and on the experimental studies of the single-β NMEs and nuclear structures associated with DBD NMEs.
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20

LITVINOV, YURI A. « MASS AND LIFETIME MEASUREMENTS AT THE PRESENT ESR FACILITY ». International Journal of Modern Physics E 18, no 02 (février 2009) : 323–34. http://dx.doi.org/10.1142/s0218301309012355.

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Mass and lifetime measurements of stored exotic nuclei is one of the successful experimental programs at the FRS-ESR facility of GSI, Darmstadt. Two experimental techniques, namely Isochronous and time-resolved Schottky mass spectrometry have been developed. Nuclides in a very broad range of half-lives starting from stable down to only a few ten microseconds can be addressed. Single stored ions can be measured which makes these techniques highly efficient. More than 1100 atomic masses have been measured meanwhile. Half-life measurements are performed with bare and few-electron ions. Decay properties of such highly-charged ions can be dramatically different from the ones known in neutral atoms. Single-particle decay spectroscopy has been developed for investigations of two-body beta decays. A brief description of the experimental methods and recent results will be presented. Future experiments at the present facility and the perspectives with the new NuSTAR/ILIMA project at FAIR will be outlined.
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21

Ejiri, Hiroyasu. « Single- and Double-Charge Exchange Reactions and Nuclear Matrix Element for Double-Beta Decay ». Universe 8, no 9 (2 septembre 2022) : 457. http://dx.doi.org/10.3390/universe8090457.

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Neutrino properties such as the Majorana nature and the masses, which go beyond the standard model, are derived from the experimental double-beta decay (DBD) rate by using the DBD nuclear matrix element (NME). Theoretical evaluations for the NME, however, are very difficult. Single-charge exchange reactions (SCERs) and double-charge exchange reactions (DCERs) are used to study nuclear isospin (τ) and spin (σ) correlations involved in the DBD NME and to theoretically calculate the DBD NME. Single and double τσ NMEs for quasi-particle states are studied by SCERs and DCER. They are found to be reduced with respect to the quasi-particle model NMEs due to the τσ correlations. The impact of the SCER- and DCER-NMEs on the DBD NME is discussed.
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22

Moreno, O., R. Álvarez-Rodríguez, E. Moya de Guerra, P. Sarriguren, F. Šimkovic et Amand Faessler. « Test of the single state dominance hypothesis for the two-neutrino double beta decay ». Journal of Physics : Conference Series 203 (1 janvier 2010) : 012063. http://dx.doi.org/10.1088/1742-6596/203/1/012063.

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23

Bondy, Aaron T., et Gordon W. F. Drake. « Charge-State Distributions after Beta Decay of 6He to Form 6Li+ ». Atoms 11, no 3 (23 février 2023) : 41. http://dx.doi.org/10.3390/atoms11030041.

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The shake-off processes and charge-state fractions of 6Li+, 6Li++, and 6Li3+ were studied following the beta decay of 6He in the 1s21S0, 1s2s1S0, and 1s2s3S1 initial states. The sudden approximation was used, together with fully correlated Hylleraas wave functions and pseudostates. A projection operator method was introduced to separate the charge-state fractions in the positive energy region of overlapping continua. The results show that 6Li++ (single-ionisation) remains dominant, even in the energy range E>0, where the formation of 6Li3+ (double-ionisation) is energetically allowed. The results reduce disagreements with the experiment for the fraction of 6Li3+ by nearly an order of magnitude, but substantial disagreements remain that are inconsistent with the sudden approximation widely used in other similar work.
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24

Kondev, F. G., D. J. Hartley, R. Orford, J. A. Clark, G. Savard, K. Auranen, A. D. Ayangeakaa et al. « Masses and Beta-decay Studies of Neutron-rich Nuclei using the X-array and Gammasphere ». EPJ Web of Conferences 223 (2019) : 01028. http://dx.doi.org/10.1051/epjconf/201922301028.

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Properties of neutron-rich nuclei in the A˜160 region are important for achieving a better understanding of the nuclear structure in this region where little is known owing to diffculties in the production of these nuclei at the present nuclear physics facilities. These properties are essential ingredients in the interpretation of the rareearth peak at A˜160 in the r process abundance distribution, since theoretical models are sensitive to nuclear structure input. Predicated on these ideas, we have initiated a new experimental program at Argonne National Laboratory. During the first experiment, beams from the Californium Rare Isotope Breeder Upgrade radioactive beam facility were used in conjunction with the SATURN decay station and the X-array. We focused initially on several odd-odd nuclei, where β decays of both the ground state and an excited isomer were investigated. Because of the spin difference, a variety of structures in the daughter nuclei were selectively populated and characterized based on their decay properties. Mass measurements using the Canadian Penning Trap aimed at establishing the excitation energy of the β-decaying isomers were also carried out. Evidence was found for a change in the single-particle structure, which in turn results in the formation of a sizable N=98 sub-shell gap at large deformation. Results from the first experimental campaign using the newly-commissioned β-decay station at Gammasphere are also presented.
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Jones, B. J. P., A. D. McDonald et D. R. Nygren. « Single molecule fluorescence imaging as a technique for barium tagging in neutrinoless double beta decay ». Journal of Instrumentation 11, no 12 (15 décembre 2016) : P12011. http://dx.doi.org/10.1088/1748-0221/11/12/p12011.

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26

Civitarese, O., H. Muther, L. D. Skouras et A. Faessler. « Single beta+-decay in26Mg : a comparison between the shell model and quasiparticle random phase approximation ». Journal of Physics G : Nuclear and Particle Physics 17, no 9 (1 septembre 1991) : 1363–73. http://dx.doi.org/10.1088/0954-3899/17/9/010.

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27

Arnaboldi, C., C. Brofferio, A. Bryant, C. Bucci, L. Canonica, S. Capelli, M. Carrettoni et al. « Production of high purity TeO2 single crystals for the study of neutrinoless double beta decay ». Journal of Crystal Growth 312, no 20 (octobre 2010) : 2999–3008. http://dx.doi.org/10.1016/j.jcrysgro.2010.06.034.

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28

Cheoun, M. K., Amand Faessler, F. Šimkovic et G. Teneva. « Two neutrino (2 ν) double and single beta decay by QRPA with neutron-proton pairing ». Progress in Particle and Nuclear Physics 32 (janvier 1994) : 315–27. http://dx.doi.org/10.1016/0146-6410(94)90028-0.

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29

Rooh, Gul, Heedong Kang, H. J. Kim, H. Park et Sih-Hong Doh. « Scintillation Characteristics of the SrCl$_{2}$ Single Crystal for the Neutrinoless $\beta^{+}$/EC Decay Search ». IEEE Transactions on Nuclear Science 55, no 3 (juin 2008) : 1445–48. http://dx.doi.org/10.1109/tns.2008.920252.

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Khan, Arshad, Pabitra Aryal, Hongjoo Kim, Moo Hyun Lee et Yeongduk Kim. « PbMoO4 Synthesis from Ancient Lead and Its Single Crystal Growth for Neutrinoless Double Beta Decay Search ». Crystals 10, no 3 (27 février 2020) : 150. http://dx.doi.org/10.3390/cryst10030150.

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A powder synthesis of PbMoO4 (PMO) from ancient lead (Pb) and deeply purified commercial MoO3 powders was performed using a wet chemistry technique to achieve the low radioactivity scintillator for neutrinoless double beta decay search in 100Mo. The synthesized powders were used to grow single crystals of PbMoO4 by the Czochralski technique in an Ar environment. The luminescence and scintillation properties were measured with excitations using UV, X- and γ-rays in the temperature range of 10–300 K. Annealing of the grown PMO crystal in an air atmosphere significantly enhanced the scintillation light yield compared to that measured before annealing. The scintillation light yield of grown PMO crystal at 10 K was found to be 127% to that of a reference PMO crystal under 662 keV γ-rays excitation from a 137Cs source. The background measurement of the grown crystal performed at 50 K shows a lower internal activity from 210Pb compared to that of reference PMO (grown from modern Pb) crystal. These preliminary performances show that the PMO crystal grown from ancient Pb and deeply purified MoO3 powders has a great potential to be used as a cryogenic scintillator for the neutrinoless double beta decay search in 100Mo.
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Sahu, R., P. C. Srivastava et V. K. B. Kota. « Deformed shell model results for two-neutrino double-beta decay of 82Se ». Canadian Journal of Physics 89, no 11 (novembre 2011) : 1101–5. http://dx.doi.org/10.1139/p11-116.

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The half-life for two-neutrino double-beta decay has been calculated for 82Se, within the framework of the deformed shell model (DSM) based on Hartree–Fock states employing a modified Kuo interaction in 2p3/2, 1f5/2, 2p1/2, and 1g9/2 space with single particle energies (relative to a 56Ni core) for the four orbitals taken as 0.0, 0.78, 1.08, and 4.25 MeV, respectively. A reasonable description is obtained for the spectroscopic properties of yrast levels in 82Se, and similarly in the past 82Kr was studied successfully using DSM. The half-life calculated using DSM is ∼3.56 × 1020 a compared to the experimental value (0.92 ± 0.07) × 1020 a. We have also recalculated the half-life by including the 1f7/2 orbit in the preceding model space using the fpg interaction introduced by Sorlin et al. (Phys. Rev. Lett. 88, 092501 (2002)). The calculated half-life is 2.05 × 1019 a (0.58 × 1020 a if we include the quenching factor of 0.77).
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SAHU, R., et V. K. B. KOTA. « DEFORMED SHELL MODEL RESULTS FOR TWO-NEUTRINO POSITRON DOUBLE BETA DECAY OF 84Sr ». International Journal of Modern Physics E 20, no 08 (août 2011) : 1723–33. http://dx.doi.org/10.1142/s021830131101957x.

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Half-lives [Formula: see text] for two-neutrino positron double beta decay modes β+ EC/ECEC are calculated for 84 Sr , a nucleus of current experimental interest, within the framework of the deformed shell model based on Hartree–Fock states employing a modified Kuo interaction in (2p3/2, 1f5/2, 2p1/2, 1g9/2) space. For a reasonable description of the spectra of 84 Sr and 84 Kr and to generate allowed GT strengths, the single particle energies of the proton and neutron 1g9/2 orbitals, relative to the 2p3/2 orbital energy, are chosen to be 3.5 MeV and 1.5 MeV for both 84 Sr and 84 Rb and 1.5 MeV and 1.5 MeV for 84 Kr . With this, the calculated half-lives for the β+ EC and ECEC modes are ~1026 yr and ~4×1024 yr respectively.
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SARRIGUREN, P., R. ÁLVAREZ-RODRÍGUEZ, O. MORENO et E. MOYA DE GUERRA. « THE GAMOW-TELLER RESPONSE IN DEFORMED NUCLEI ». International Journal of Modern Physics E 15, no 07 (octobre 2006) : 1397–406. http://dx.doi.org/10.1142/s0218301306004958.

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We study Gamow-Teller strength distributions within a QRPA approach performed on top of a deformed Skyrme-Hartree-Fock+BCS single particle basis with the inclusion of residual spin-isospin interactions in both particle-hole and particle-particle channels. We focus our attention in several problems of interest in Nuclear Structure and Nuclear Astrophysics, such as the β-decay properties of proton-rich medium-mass nuclei of astrophysical interest and the deformation dependence of the Gamow-Teller strength distributions in neutron deficient Pb isotopes. We also discuss the role of deformation in the two-neutrino double beta decay.
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FIORINI, ETTORE. « NEUTRINO IN PHYSICS AND ASTROPHYSICS ». International Journal of Modern Physics D 22, no 11 (septembre 2013) : 1360003. http://dx.doi.org/10.1142/s0218271813600031.

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The recent impact of the discovery of neutrino oscillations and the related evidence of a finite neutrino mass has stimulated searches to actually measure or constraint the effective mass of this particle. Present and planned experiments based on cosmology and on single and double beta decay will be reviewed together with the suggested possibility of a Majorana nature of the neutrino.
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Michel, Thilo, Thomas Gleixner, Jürgen Durst, Mykhaylo Filipenko et Stefan Geißelsöder. « The Potential of Hybrid Pixel Detectors in the Search for the Neutrinoless Double-Beta Decay of116Cd ». Advances in High Energy Physics 2013 (2013) : 1–20. http://dx.doi.org/10.1155/2013/105318.

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We investigated the potential of the energy resolving hybrid pixel detector Timepix contacted to a CdTe sensor layer for the search for the neutrinoless double-beta decay ofCd. We found that a CdTe sensor layer with 3 mm thickness and 165 μm pixel pitch is optimal with respect to the effective Majorana neutrino mass (mββ) sensitivity. In simulations, we were able to demonstrate a possible reduction of the background level caused by single electrons by approximately 75% at a specific background rate of 10−3counts/(kg×keV×yr) at a detection efficiency reduction of about 23% with track analysis employing random decision forests. Exploitation of the imaging properties with track analysis leads to an improvement in sensitivity tomββby about 22%. After 5 years of measuring time, the sensitivity tomββof a 420 kg CdTe experiment (90%Cdenrichment) would be 59 meV on a 90% confidence level for a specific single-electron background rate of 10−3counts/(kg×keV×yr). Theα-particle background can be suppressed by at least about six orders of magnitude. The benefit of the hybrid pixel detector technology might be increased significantly if drift-time difference measurements would allow reconstruction of tracks in three dimensions.
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SUHONEN, JOUNI. « NUCLEAR-STRUCTURE EFFECTS ON DOUBLE BETA DECAYS TO 0+ STATES IN 76Ge ». International Journal of Modern Physics E 20, no 02 (février 2011) : 451–58. http://dx.doi.org/10.1142/s0218301311017843.

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Neutrinoless double beta (0νββ) decay of 76 Ge to the ground state and first excited 0+ state in 76 Se is discussed in terms of the associated nuclear matrix elements. The effects arizing from the size of the single-particle model space and the occupancies of the individual orbits are discussed in the framework of the (higher) quasiparticle random-phase approximation with effective, G -matrix-derived nuclear forces. It is found that the orbital occupancies play a role for the size of the nuclear matrix element. Contrary to the ground-state transition the transition to the first excited 0+ state does not depend sensitively on the size of the model space.
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37

Sah, P. « Role of calcium influx and buffering in the kinetics of Ca(2+)-activated K+ current in rat vagal motoneurons ». Journal of Neurophysiology 68, no 6 (1 décembre 1992) : 2237–47. http://dx.doi.org/10.1152/jn.1992.68.6.2237.

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1. Intracellular recordings were obtained from neurons of the dorsal motor nucleus of the vagus (DMV) in transverse slices of the rat medulla maintained in vitro. These neurons had a resting potential of -59.8 +/- 8.7 (SD) mV. Single action potentials elicited by brief depolarizing current pulses were followed by a prolonged afterhyperpolarization (AHP). Under voltage clamp, the current underlying the AHP was found to be a calcium-activated potassium current. 2. The outward current (GkCa,1) was voltage insensitive and was not blocked by tetraethylammonium (TEA) (10 mM). Unlike the slower time course calcium-activated potassium current recorded in some other neurons, GkCa,1 was blocked by apamin (25-100 nM), indicating that SK type calcium-activated potassium channels underlie this current. 3. GkCa,1 was maximal within 10 ms of the action potential and its decay was well described by a single exponential. After a single action potential the time constant of decay of GkCa,1 was 155 +/- 66 (+/- SD) ms. 4. Calcium influx was increased by adding TEA to the extracellular solution or by firing more than one action potential. As the calcium load was increased, both the peak amplitude and the time constant of decay of GkCa,1 increased. In cells impaled with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)-filled electrodes, the time constant of decay of GkCa,1 after a single action current was 71 +/- 19 ms. 5. A simple diffusion-based model that incorporates two intrinsic calcium buffers is developed that accounts for many of the properties of GkCa,1. It is concluded that the decay of GkCa,1 reflects the time course of removal of calcium that has entered the cell during the action potential.
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38

Theodórsson, Pall. « Simultaneously Measuring 14C and Radon in Benzene Dating Samples ». Radiocarbon 47, no 2 (2005) : 231–34. http://dx.doi.org/10.1017/s0033822200019731.

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After benzene synthesis, radiocarbon dating samples are usually stored for 3–4 weeks before counting to allow an eventual radon contamination to decay to a negligible level. This paper presents a technique that can minimize, and often eliminate, this delay by using a simple single-phototube liquid scintillation counting system, specifically designed for 14C dating. Radon contamination is assessed by pulses of 214Po (a 222Rn decay product, half-life 0.16 μs), identified through pulse-time analysis. For each 214Po pulse, 0.49 beta particle pulses of 214Pb and 214Bi fall in the 14C counting window, and the 214Po pulses are used to correct the 14C count rate. A 14C sample (count rate 11.6 cpm) was measured continuously for 16 days. It was then doped with radon, which increased the first 24-hr count rate in the 14C channel by 3.8 cpm, and the sample was measured for 27 more days. Radon did not measurably affect the 14C-corrected count rate. Counting a sample for 2 min reveals whether it needs storing. If the radon concentration is low, the sample can be measured immediately without degrading accuracy.
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39

Rittirong, A., T. Yoshimoto, R. Hazama, T. Kishimoto, T. Fujii, Y. Sakuma, S. Fukutani, Y. Shibahara et A. Sunaga. « Isotope separation by DC18C6 crown-ether for neutrinoless double beta decay of 48Ca ». Journal of Physics : Conference Series 2147, no 1 (1 janvier 2022) : 012015. http://dx.doi.org/10.1088/1742-6596/2147/1/012015.

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Abstract The isotope separation via liquid-liquid extraction (LLE) using crown-ether (DC18C6) was carried out in order to demonstrate the feasibility of calcium isotope enrichment, which aimed to find a cost-effective way to enrich calcium-48 (48Ca) for the study of neutrinoless double beta decay (0vββ) in the CANDLES project. The LLE results revealed that the extraction was solvent dependent in the presence of HCl and the distribution coefficient (D) increased approximately threefold (0.0546±0.0012) with 12 M HCl solvent under a 3.9 M CaCl2 (aq) (30% w/w) system. Furthermore, the HCl solvent maintained the calcium content attached to the crown-ether at lower feed concentrations. The reaction cell ICP-MS (Agilent 7900) with an additional H2 gas was used to analyze the isotopic composition. The single-stage separation factor of organic phase was found to be 0.992±0.003, 0.994±0.003, 0.996±0.004 for 48Ca/42Ca, 48Ca/43Ca, and 48Ca/44Ca, respectively in the extracted organic phase of 3.3 M CaCl2 (aq) (30% w/w) system. The obtained results were comparable with the HCl solvent system. As a result, without the addition of an acidity reagent, the production of the enriched 48Ca isotope via LLE was highly feasible. To improve the mass production of enriched 48Ca, filter separation was applied in order to shorten the time required and to study various volumes of the extraction system. The results indicated that the extraction efficiency of filter LLE was comparable to conventional LLE. Filter LLE resulted in more than threefold reduction in time required (approximately 10 minutes for a complete single-stage separation) in comparison with a conventional LLE, consequently implying great potential in the enrichment and mass production via filter LLE.
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40

Ebrahiem, Sameera Ahmed, et Taghreed A. Younis. « Finding Most Stable Isobar for Nuclides with Mass Number (165- 175) against Beta Decay ». NeuroQuantology 19, no 4 (18 mai 2021) : 15–19. http://dx.doi.org/10.14704/nq.2021.19.4.nq21032.

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In the beta decay process, a neutron converts into a proton, or vice versa, so the atom in this process changes to a more stable isobar. Bethe-Weizsäcker used a quasi-experimental formula in the present study to find the most stable isobar for isobaric groups of mass nuclides (A=165-175). In a group of isobars, there are two methods of calculating the most stable isobar. The most stable isobar represents the lowest parabola value by calculating the binding energy value (B.E) for each nuclide in this family, and then drawing these binding energy values as a function of the atomic number (Z) in order to obtain the mass parabolas, the second method is by calculating the atomic number value of the most stable isobar (ZA). The results show that the mass parabolas of isobar elements with an even mass number (A=even) vary from the mass parabolas of isobar elements with an odd mass number (A=odd), In the case of single isobars, it has one parabola, meaning that it has one stable isobar, while we find that the pairs isobars appear to have two parabolas, meaning that it has more than one stable isobar. When we compared the two methods used in this study to determine the most stable isobars, we found that in two techniques for odd isobars, stable isobars are mostly the same nuclide, whereas in suitcases of even isobars with two stable isobars (only one of them are same stable isobars).
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41

van der Graaf, Harry. « Single electron sensitive GridPix TPCs and their application in Dark Matter search and v-less Double Beta Decay Experiments ». Journal of Physics : Conference Series 309 (10 août 2011) : 012016. http://dx.doi.org/10.1088/1742-6596/309/1/012016.

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42

Raduta, A. A., et C. M. Raduta. « Double beta decay to the first 2+ state within a boson expansion formalism with a projected spherical single particle basis ». Physics Letters B 647, no 4 (avril 2007) : 265–70. http://dx.doi.org/10.1016/j.physletb.2007.02.007.

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43

Ackerman, N., J. Albert, M. Auger, D. J. Auty, I. Badhrees, P. S. Barbeau, L. Bartoszek et al. « The EXO-200 detector, part II : auxiliary systems ». Journal of Instrumentation 17, no 02 (1 février 2022) : P02015. http://dx.doi.org/10.1088/1748-0221/17/02/p02015.

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Abstract The EXO-200 experiment searched for neutrinoless double-beta decay of 136Xe with a single-phase liquid xenon detector. It used an active mass of 110 kg of 80.6%-enriched liquid xenon in an ultra-low background time projection chamber with ionization and scintillation detection and readout. This paper describes the design and performance of the various support systems necessary for detector operation, including cryogenics, xenon handling, and controls. Novel features of the system were driven by the need to protect the thin-walled detector chamber containing the liquid xenon, to achieve high chemical purity of the Xe, and to maintain thermal uniformity across the detector.
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44

O'Rourke, B., D. K. Reibel et A. P. Thomas. « High-speed digital imaging of cytosolic Ca2+ and contraction in single cardiomyocytes ». American Journal of Physiology-Heart and Circulatory Physiology 259, no 1 (1 juillet 1990) : H230—H242. http://dx.doi.org/10.1152/ajpheart.1990.259.1.h230.

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A charge-coupled device (CCD) camera, with the capacity for simultaneous spatially resolved photon counting and rapid frame transfer, was utilized for high-speed digital image collection from an inverted epifluorescence microscope. The unique properties of the CCD detector were applied to an analysis of cell shortening and the Ca2+ transient from fluorescence images of fura-2-loaded [corrected] cardiomyocytes. On electrical stimulation of the cell, a series of sequential subimages was collected and used to create images of Ca2+ within the cell during contraction. The high photosensitivity of the camera, combined with a detector-based frame storage technique, permitted collection of fluorescence images 10 ms apart. This rate of image collection was sufficient to resolve the rapid events of contraction, e.g., the upstroke of the Ca2+ transient (less than 40 ms) and the time to peak shortening (less than 80 ms). The technique was used to examine the effects of beta-adrenoceptor activation, fura-2 load, and stimulus frequency on cytosolic Ca2+ transients and contractions of single cardiomyocytes. beta-Adrenoceptor stimulation resulted in pronounced increases in peak Ca2+, maximal rates of rise and decay of Ca2+, extent of shortening, and maximal velocities of shortening and relaxation. Raising the intracellular load of fura-2 had little effect on the rising phase of Ca2+ or the extent of shortening but extended the duration of the Ca2+ transient and contraction. In related experiments utilizing differential-interference contrast microscopy, the same technique was applied to visualize sarcomere dynamics in contracting cells. This newly developed technique is a versatile tool for analyzing the Ca2+ transient and mechanical events in studies of excitation-contraction coupling in cardiomyocytes.
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45

Stokes, C. L., D. A. Lauffenburger et S. K. Williams. « Migration of individual microvessel endothelial cells : stochastic model and parameter measurement ». Journal of Cell Science 99, no 2 (1 juin 1991) : 419–30. http://dx.doi.org/10.1242/jcs.99.2.419.

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Analysis of cell motility effects in physiological processes can be facilitated by a mathematical model capable of simulating individual cell movement paths. A quantitative description of motility of individual cells would be useful, for example, in the study of the formation of new blood vessel networks in angiogenesis by microvessel endothelial cell (MEC) migration. In this paper we propose a stochastic mathematical model for the random motility and chemotaxis of single cells, and evaluate migration paths of MEC in terms of this model. In our model, cell velocity under random motility conditions is described as a persistent random walk using the Ornstein-Uhlenbeck (O-U) process. Two parameters quantify this process: the magnitude of random movement accelerations, alpha, and a decay rate constant for movement velocity, beta. Two other quantities often used in measurements of individual cell random motility properties—cell speed, S, and persistence time in velocity, Pv—can be defined in terms of the fundamental stochastic parameters alpha and beta by: S =square root (alpha/beta) and Pv = 1/beta. We account for chemotactic cell movement in chemoattractant gradients by adding a directional bias term to the O-U process. The magnitude of the directional bias is characterized by the chemotactic responsiveness, kappa. A critical advantage of the proposed model is that it can generate, using experimentally measured values of alpha, beta and kappa, computer simulations of theoretical individual cell paths for use in evaluating the role of cell migration in specific physiological processes. We have used the model to assess MEC migration in the presence of absence of the angiogenic stimulus acidic fibroblast growth factor (aFGF). Time-lapse video was used to observe and track the paths of cells moving in various media, and the mean square displacement was measured from these paths. To test the validity of the model, we compared the mean square displacement measurements of each cell with model predictions of that displacement. The comparison indicates that the O-U process provides a satisfactory description of the random migration at this level of comparison. Using nonlinear regression in these comparisons, we measured the magnitude of random accelerations, alpha, and the velocity decay rate constant, beta, for each cell path. We consequently obtained values for the derived quantities, speed and persistence time. In control medium, we find that alpha = 250 +/− 100 microns 2h-3 and beta = 0.22 +/− 0.03h-1, while in stimulus medium (control plus unpurified aFGF) alpha = 1900 +/− 720 microns 2h-3 and beta = 0.99 +/− 0.37h-1.(ABSTRACT TRUNCATED AT 400 WORDS)
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46

Das, Pritam, et Mrinal Kumar Das. « Phenomenology of keV sterile neutrino in minimal extended seesaw ». International Journal of Modern Physics A 35, no 22 (7 août 2020) : 2050125. http://dx.doi.org/10.1142/s0217751x20501250.

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We explore the possibility of a single generation of keV scale sterile neutrino [Formula: see text] as a dark matter candidate within the minimal extended seesaw (MES) framework and its influence in neutrinoless double beta decay [Formula: see text] study. Three hierarchical right-handed neutrinos were considered to explain neutrino mass. We also address baryogenesis via the mechanism of thermal leptogenesis considering the decay of the lightest RH neutrino to a lepton and Higgs doublet. A generic model based on [Formula: see text] flavor symmetry is constructed to explain both normal and inverted hierarchy mass pattern of neutrinos. Significant results on effective neutrino masses are observed in presence of sterile mass [Formula: see text] and active-sterile mixing [Formula: see text] in [Formula: see text]. Results from [Formula: see text] give stringent upper bounds on the active-sterile mixing matrix element. To establish sterile neutrino as dark matter within this model, we checked decay width and relic abundance of the sterile neutrino, which restricted sterile mass [Formula: see text] within some definite bounds. Constrained regions on the CP phases and Yukawa couplings are obtained from [Formula: see text] and baryogenesis results. Co-relations among these observable are also established and discussed within this framework.
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47

FUKUYAMA, TAKESHI, et HIROYUKI NISHIURA. « MODEL INDEPENDENT CONSTRAINTS OF THE AVERAGED NEUTRINO MASSES REVISITED ». Modern Physics Letters A 28, no 39 (16 décembre 2013) : 1350186. http://dx.doi.org/10.1142/s0217732313501861.

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Averaged neutrino masses defined by [Formula: see text] are reanalyzed using up-to-date observed MNS parameters and neutrino masses by the neutrino oscillation experiments together with the cosmological constraint on neutrino masses. The values of 〈mν〉ab are model-independently evaluated in terms of effective neutrino mass defined by [Formula: see text] which is observable in the single beta decay. We obtain lower bound for 〈mν〉ee in the inverted hierarchy (IH) case, 17 meV ≤〈mν〉ee and one for 〈mν〉τμ in the normal hierarchy (NH) case, 5 meV ≤〈mν〉τμ. We also obtain that all the averaged masses 〈mν〉ab have upper bounds which are at most 80 meV.
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48

Richard, S., F. Tiaho, P. Charnet, J. Nargeot et J. M. Nerbonne. « Two pathways for Ca2+ channel gating differentially modulated by physiological stimuli ». American Journal of Physiology-Heart and Circulatory Physiology 258, no 6 (1 juin 1990) : H1872—H1881. http://dx.doi.org/10.1152/ajpheart.1990.258.6.h1872.

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In cardiac muscle, Ca2+ entry through voltage-gated Ca2+ channels plays an important role in the generation of action potentials and in the development of tension. Although it had been assumed that there was a single type of cardiac Ca2+ channel, recent studies reveal that multiple Ca2+ channel types coexist in some myocardial cells. Here, we report that macroscopic Ca2+ current (ICa) waveforms in isolated adult rat ventricular myocytes comprise two kinetically distinct components; these are referred to here as ICa (fc) and ICa (sc) to denote the fast and slow components, respectively, of ICa decay. In contrast to findings in other cells, the properties of ICa (fc) and ICa (sc) suggest the presence of two pathways for gating of a single type of high-threshold Ca2+ channel rather than two distinct Ca2+ channel types. In addition, gating via ICa (fc) and ICa (sc) is regulated by changes in membrane potential and stimulation frequency. Hyperpolarized potentials and low stimulation frequencies reveal preferential activation via ICa (fc); depolarized potentials and high stimulation frequencies, in contrast, favor activation via ICa (sc). After exposure to beta-adrenergic agonists or the Ca2+ agonist BAY K 8644, peak ICa amplitudes increase owing to the preferential augmentation of ICa (fc); beta-agonists and BAY K 8644 also increase ICa (sc), albeit to a smaller extent than ICa (fc). Thus, in addition to voltage- and frequency-dependent regulation, the two pathways for Ca2+ channel gating are modulated differentially by beta-adrenergic and Ca2+ channel agonists.
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Shen, Dili, Wuyi Ming, Xinggui Ren, Zhuobin Xie, Yong Zhang et Xuewen Liu. « A Cuckoo Search Algorithm Using Improved Beta Distributing and Its Application in the Process of EDM ». Crystals 11, no 8 (6 août 2021) : 916. http://dx.doi.org/10.3390/cryst11080916.

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Lévy flights random walk is one of key parts in the cuckoo search (CS) algorithm to update individuals. The standard CS algorithm adopts the constant scale factor for this random walk. This paper proposed an improved beta distribution cuckoo search (IBCS) for this factor in the CS algorithm. In terms of local characteristics, the proposed algorithm makes the scale factor of the step size in Lévy flights showing beta distribution in the evolutionary process. In terms of the overall situation, the scale factor shows the exponential decay trend in the process. The proposed algorithm makes full use of the advantages of the two improvement strategies. The test results show that the proposed strategy is better than the standard CS algorithm or others improved by a single improvement strategy, such as improved CS (ICS) and beta distribution CS (BCS). For the six benchmark test functions of 30 dimensions, the average rankings of the CS, ICS, BCS, and IBCS algorithms are 3.67, 2.67, 1.5, and 1.17, respectively. For the six benchmark test functions of 50 dimensions, moreover, the average rankings of the CS, ICS, BCS, and IBCS algorithms are 2.83, 2.5, 1.67, and 1.0, respectively. Confirmed by our case study, the performance of the ABCS algorithm was better than that of standard CS, ICS or BCS algorithms in the process of EDM. For example, under the single-objective optimization convergence of MRR, the iteration number (13 iterations) of the CS algorithm for the input process parameters, such as discharge current, pulse-on time, pulse-off time, and servo voltage, was twice that (6 iterations) of the IBCS algorithm. Similar, the iteration number (17 iterations) of BCS algorithm for these parameters was twice that (8 iterations) of the IBCS algorithm under the single-objective optimization convergence of Ra. Therefore, it strengthens the CS algorithm’s accuracy and convergence speed.
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LaRoque, Benjamin. « Zero-deadtime processing in beta spectroscopy for measurement of the non-zero neutrino mass ». EPJ Web of Conferences 245 (2020) : 01014. http://dx.doi.org/10.1051/epjconf/202024501014.

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The Project 8 collaboration seeks to measure, or more tightly bound, the mass of the electron antineutrino by applying a novel spectroscopy technique to precisely measure the tritium beta-decay spectrum. The current system produces a single analog signal, which is digitized and processed in several stages before being saved to local disk storage. Online processing includes two stages, an FPGA connected to the analog to digital converter reduces the data down to the region of interest before shipping over the local network for further processing and storage. A normal CPU-based processing stage applies triggering logic to only save data at times when a signal is present, further reducing the total volume of data which needs to be written to disk or transferred for long-term storage. The next stage of the project will need to process many input channels and will integrate a necessary aggregation and combination step prior to applying the event search and triggering logic. We present the online processing system which has successfully been deployed for the current, singlechannel, phase. We also present the status and design for a many-channel platform.
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