Showing papers by "S. Roccia published in 2010"
TL;DR: In this paper, the Gamow-Teller decay was measured by polarizing the radioactive nuclei with the brute force low-temperature nuclear-orientation method, and the result was in agreement with the Standard-Model value of $-0.014(12)_{stat}(16)
Abstract: The $\beta$-asymmetry parameter $\widetilde{A}$ for the Gamow-Teller decay of $^{60}$Co was measured by polarizing the radioactive nuclei with the brute force low-temperature nuclear-orientation method. The $^{60}$Co activity was cooled down to milliKelvin temperatures in a $^3$He-$^4$He dilution refrigerator in an external 13 T magnetic field. The $\beta$ particles were observed by a 500 ${\mu}m$ thick Si PIN diode operating at a temperature of about 10 K in a magnetic field of 0.6 T. Extensive GEANT4 Monte-Carlo simulations were performed to gain control over the systematic effects. Our result, $\widetilde{A} = -1.014(12)_{stat}(16)_{syst}$, is in agreement with the Standard-Model value of $-0.987(9)$, which includes recoil-order corrections that were addressed for the first time for this isotope. Further, it enables limits to be placed on possible tensor-type charged weak currents as well as other physics beyond the Standard Model.
29 citations
TL;DR: In this paper, an original test of Lorentz invariance in the interaction between a particle spin and an electromagnetic field and report on the first measurement using ultracold neutrons.
Abstract: We propose an original test of Lorentz invariance in the interaction between a particle spin and an electromagnetic field and report on a first measurement using ultracold neutrons. We used a high-sensitivity neutron electric dipole moment (nEDM) spectrometer and searched for a direction dependence of an nEDM signal leading to a modulation of its magnitude at periods of 12 and 24 hours. We constrain such a modulation to d12 1010 GeV.
18 citations
TL;DR: In this paper, an original test of Lorentz invariance in the interaction between a particle spin and an electromagnetic field and report on the first measurement using ultracold neutrons.
Abstract: We propose an original test of Lorentz invariance in the interaction between a particle spin and an electromagnetic field and report on a first measurement using ultracold neutrons. We used a high sensitivity neutron electric dipole moment (nEDM) spectrometer and searched for a direction dependence of a nEDM signal leading to a modulation of its magnitude at periods of 12 and 24 hours. We constrain such a modulation to $d_{12} 10^{10}$~GeV.
13 citations
TL;DR: In this article, the half-life of the alpha-decaying nucleus {sup 221}Fr was determined in different environments, that is, embedded in Si at 4 K, and embedded in Au at 4 k and about 20 mK.
Abstract: The half-life of the {alpha}-decaying nucleus {sup 221}Fr was determined in different environments, that is, embedded in Si at 4 K, and embedded in Au at 4 K and about 20 mK. No differences in half-life for these different conditions were observed within 0.1%. Furthermore, we quote a value for the absolute half-life of {sup 221}Fr of t{sub 1/2}=286.1(10) s that is of comparable precision to the most precise value available in the literature.
6 citations
TL;DR: In this article, the status of the new measurement of the neutron electric dipole moment (nEDM) to be performed at the strong source of ultra-cold neutrons at the Paul Scherrer Institut is described.
6 citations