Search results for "SEP"
showing 10 items of 2642 documents
Energy-independent new physics in the flavour ratios of high-energy astrophysical neutrinos
2010
We have studied the consequences of breaking the CPT symmetry in the neutrino sector, using the expected high-energy neutrino flux from distant cosmological sources such as active galaxies. For this purpose we have assumed three different hypotheses for the neutrino production model, characterised by the flavour fluxes at production phi(0)(e) : phi(0)(mu) : phi(0)(tau) = 1 : 2 : 0, 0 : 1 : 0, and 1 : 0 : 0, and studied the theoretical and experimental expectations for the muon-neutrino flux at Earth, phi(mu), and for the flavour ratios at Earth, R = phi(mu)/phi(e) and S = phi(tau)/phi(mu). CPT violation (CPTV) has been implemented by adding an energy-independent term to the standard neutrin…
Low-energy scattering and photoproduction ofηmesons on three-body nuclei
2003
The optical potential approach for low-energy scattering of $\eta$-mesons on three-body nuclei is compared to an exact treatment of the $\eta 3N$ system using four-body scattering theory with separable interactions in s-waves only. The higher-order terms including the interaction of the struck nucleon with the surrounding nuclear medium and virtual target excitations in between successive $\eta$-scatterings are found to cause important corrections. Effects of final state interaction in $\eta$-photoproduction on $^3$H and $^3$He are also studied and sizable contributions beyond the optical model approach are found.
SKYRME-RANDOM-PHASE-APPROXIMATION DESCRIPTION OF SPIN-FLIP AND ORBITAL M1 GIANT RESONANCES
2010
The self-consistent separable random-phase approximation (SRPA) with Skyrme forces is extended to the case of magnetic excitations and applied to the description of spin-flip and orbital M1 giant resonances in the isotopic chain 142-152 Nd . The Skyrme forces SkT6, SkM*, SLy6 and SkI3 are used. The calculations show an onset of the scissors mode with increasing deformation. A specific three-peak structure of the spin-flip response is found and explained by particular neutron and proton spin-flip transitions. Although the employed forces provide an acceptable qualitative description, the Skyrme functional still needs further improvement to reproduce quantitatively the experiment for spin mo…
Identification of low-lying proton-based intruder states in189–193Pb
2002
Low-lying proton-based intruder states have been observed in the odd-mass isotopes Pb-189,Pb-191,Pb-193 in experiments at the RITU gas-filled recoil separator. The identification has been performed ...
The discovery of the serendipitous X-ray pulsar SAX J1802.7–2017 from a BeppoSAX observation of GX 9+1
2004
Abstract We have discovered a new X-ray source, SAX J1802.7–2017, ∼22′ away from the bright X-ray source GX 9+1, during a BeppoSAX observation of this latter one on 2001 September 16-20. The count rate of SAX J1802.7–2017 is comparable to the background (∼0.04 c/s) during the first 50 ks of the observation, then the count rate shows a large variability increasing up to ∼0.28 c/s. We have performed a temporal analysis finding that SAX J1802.7–2017 has a pulse period of ∼139.61 s, a projected orbital separation a x sin i of 48±5 lt-s and an orbital period of 3.7 +0.4 −0.2 days, allowing to classify the new object as an X-ray pulsar.
Two-proton emission in the decay of Ar-31
1998
18 pages, 7 figures, 2 tables.-- PACS nrs.: 23.40.Hc; 27.30.+t.
Breakthrough in pulse-shape based particle identification with silicon detectors
2000
Identification of charged particles is an important method in nuclear spectroscopy. We have achieved a major breakthrough that makes the pulse-shape discrimination (PSD) method with a single solid-state detector comparable to and sometimes better than the traditional telescope technique. By using rear-side injection in over-biased surface barrier n-type Si detectors made from homogeneously doped n-TD silicon, and extracting the pulse-shape information already at the preamplifier level we have reached improved Z and even A discrimination over a wide dynamic range. Previously good separation with the PSD technique required a major degradation of time resolution and inferior energy resolution.…
Spectroscopy ofAt201including the observation of a shears band and the29/2+isomeric state
2015
The excited states of $^{201}\mathrm{At}$ were studied and an isomeric $29/{2}^{+}$ state $[{T}_{\textonehalf{}}=3.39(9)\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{s}]$ was identified by using a fusion-evaporation reaction, a gas-filled recoil separator, and recoil gating techniques. The $29/{2}^{+}$ state is suggested to originate from the $\ensuremath{\pi}({h}_{9/2})\ensuremath{\bigotimes}|^{200}\mathrm{Po};{11}^{\ensuremath{-}}\ensuremath{\rangle}$ configuration, and it decays through the 269- and 339-keV $E2$- and $E3$-type transitions, respectively. Moreover, a cascade of magnetic dipole transitions that is suggested to originate from a shears band was observed by using recoil-…
First isochronous mass spectrometry at the experimental storage ring ESR
2000
Short-lived exotic nuclei can be produced and separated with the high-energy secondary nuclear beam facility FRS at GSI. These nuclides can be injected and stored in the storage ring ESR. The lower lifetime limit of the presently existing methods for mass measurements on these nuclides at the ESR is about a few seconds. We have developed and investigated an isochronous operational mode of the ESR, that makes mass measurements of nuclides with lifetimes down to a few ls feasible. It has been commissioned in experiments using long-lived nuclides with known masses. A mass resolving power of about 150 000 has been achieved in a "rst pilot experiment. A suitable detector system has been implemen…
The decay of 31 sec98Zr, 2.9 sec98Nb and 51 min98Nb
1976
TheΒ- andγ-radiations of98Zr and98m, g Nb have been investigated employing scintillation and semiconductor spectrometers and coincidence techniques. Sources of98Nb were produced by the98Mo(n, p)98Nb reaction, sources of98Zr by fission of235U with thermal neutrons applying chemical separations. For98Zr, a half-life of 30.7±0.4 sec and aQ β-value of 2.3±0.2 MeV were obtained, for the98Nb isomers, half-lives of 2.86±0.06 sec and 51.3±0.4 min, andQ β-values of 4.8±0.2 MeV and 4.5±0.2 MeV, respectively. Noγ-rays were observed in the decay of98Zr. The decay of 2.9 sec98Nb was found to involve 11γ-ray transitions. In the decay of 51 min98Nb, 54γ-transitions were detected. Spin and parity of 1+ and…