AGATA Collaboration(Ralet, D. et al), Gadea, A., & Perez-Vidal, R. M. (2017). Toward lifetime and g factor measurements of short-lived states in the vicinity of Pb-208. Phys. Scr., 92(5), 054004–4pp.
Abstract: The multi-nucleon transfer reaction mechanism was used to produce and study nuclei in the vicinity of 208Pb. This mass region is a test case for the nuclear shell model. The mass identification of the fragments was performed with the large acceptance magnetic spectrometer VAMOS++ coupled to the AGATA gamma-tracking array. This experiment aimed to determine both lifetimes and gyromagnetic ratios of excited states with the Cologne plunger device. The analysis indicates promising results with the possibility to determine several new lifetimes in this region.
|
ALEPH, D. E. L. P. H. I., L3 and OPAL Collaborations, LEP Electroweak Working Group(Schael, S. et al), Costa, M. J., Ferrer, A., Fuster, J., Garcia, C., Oyanguren, A., et al. (2013). Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP. Phys. Rep., 532(4), 119–244.
Abstract: Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma – 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019.
|
Gariazzo, S., Mena, O., & Schwetz, T. (2023). Quantifying the tension between cosmological and terrestrial constraints on neutrino masses. Phys. Dark Universe, 40, 101226–8pp.
Abstract: The sensitivity of cosmology to the total neutrino mass scale E m & nu; is approaching the minimal values required by oscillation data. We study quantitatively possible tensions between current and forecasted cosmological and terrestrial neutrino mass limits by applying suitable statistical tests such as Bayesian suspiciousness, parameter goodness-of-fit tests, or a parameter difference test. In particular, the tension will depend on whether the normal or the inverted neutrino mass ordering is assumed. We argue, that it makes sense to reject inverted ordering from the cosmology/oscillation comparison only if data are consistent with normal ordering. Our results indicate that, in order to reject inverted ordering with this argument, an accuracy on the sum of neutrino masses & sigma;(m & nu;) of better than 0.02 eV would be required from future cosmological observations.
|
Gil, A., Diaz, J., Gomez-Cadenas, J. J., Herrero, V., Rodriguez, J., Serra, L., et al. (2012). Front-end electronics for accurate energy measurement of double beta decays. Nucl. Instrum. Methods Phys. Res. A, 695, 407–409.
Abstract: NEXT, a double beta decay experiment that will operate in Canfranc Underground Laboratory (Spain), aims at measuring the neutrinoless double-beta decay of the 136Xe isotope using a TPC filled with enriched Xenon gas at high pressure operated in electroluminescence mode. One technological challenge of the experiment is to achieve resolution better than 1% in the energy measurement using a plane of UV sensitive photomultipliers readout with appropriate custom-made front-end electronics. The front-end is designed to be sensitive to the single photo-electron to detect the weak primary scintillation light produced in the chamber, and also to be able to cope with the electroluminescence signal (several hundred times higher and with a duration of microseconds). For efficient primary scintillation detection and precise energy measurement of the electroluminescent signals the front-end electronics features low noise and adequate amplification. The signal shaping provided allows the digitization of the signals at a frequency as low as 40 MHz.
|
Goasduff, A., Valiente-Dobon, J. J., Lunardi, S., Haas, F., Gadea, A., de Angelis, G., et al. (2014). Counting rate measurements for lifetime experiments using the RDDS method with the new generation gamma-ray array AGATA. Nucl. Instrum. Methods Phys. Res. A, 758, 1–3.
Abstract: The differential Recoil Distance Doppler Shift (RDDS) method after multinucleon transfer (MNT) reactions to measure lifetimes of excited states in neutron-rich nuclei requires the use of a thick energy degrader for the recoiling ejectiles that are then detected in a spectrometer. This type of measurements greatly benefits from the use of the new generation segmented gamma-ray detectors, such as the AGATA demonstrator which offers unprecedented energy and angular resolutions. In order to make an optimized choice of the material and the thickness of the degrader for lifetime measurements using the RODS method after MNT, an experiment has been performed with the AGATA demonstrator. Counting rate measurements for different degraders are presented.
|
