Search results for "Spectral"
showing 10 items of 3116 documents
Persistence of the Z=28 shell gap in A=75 isobars: Identification of a possible (1/2−) μs isomer in Co75 and β decay to Ni75
2021
Background: The evolution of shell structure around doubly-magic exotic nuclei is of great interest in nuclear physics and astrophysics. In the `south-west' region of $^{78}$Ni, the development of deformation might trigger a major shift in our understanding of explosive nucleosynthesis. To this end, new spectroscopic information on key close-lying nuclei is very valuable. Purpose: We intend to measure the isomeric and $\beta$ decay of $^{75}$Co, with one proton- and two neutron-holes relative to $^{78}$Ni, to access new nuclear structure information in $^{75}$Co and its $\beta$-decay daughters $^{75}$Ni and $^{74}$Ni. Methods: The nucleus $^{75}$Co is produced in relativistic in-flight fiss…
Direct Observation of aρDecay of theD13(1520)Baryon Resonance
2001
The reaction {gamma}p{yields}{pi}{sup +}{pi}{sup 0}n has been measured at MAMI for photon energies up to 820MeV. Invariant mass spectra of the particles in the final state ({pi}{sup +}n) , ({pi}{sup 0}n) , ({pi}{sup +}{pi}{sup 0}) have been determined for several bins of incident photon energy. Differences in {pi}{sup +}{pi}{sup 0} and simultaneously measured {pi}{sup 0}{pi}{sup 0} invariant mass distributions are assigned to a {rho} branch of the D{sub 13}(1520) nucleon resonance.
Target thickness dependence of the Be(p,xn) neutron energy spectrum
2014
We report on the current status of the analysis of an experiment performed at The Svedberg Laboratory, with the aim of investigating the produced neutron field by Be(p,xn) converters of three different thicknesses with a 30 MeV proton beam. The neutron energy spectra were measured with the Time of Flight technique using a BC-501 liquid scintillator with good n-γ Pulse Shape Discrimination properties, while the detected events were recorded simultaneously by two Data AcQuisition systems. In this paper, we present the experimental setup, the analysis technique and some preliminary results. AlFONS
Unveiling the K1(1270) double-pole structure in the B¯→J/ψρK¯ and B¯→J/ψK¯*π decays
2021
By looking at the pseudoscalar-vector meson spectra in the $\overline{B}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\rho}\overline{K}$ and $\overline{B}\ensuremath{\rightarrow}J/\ensuremath{\psi}{\overline{K}}^{*}\ensuremath{\pi}$ weak decays, we theoretically investigate the double-pole structure of the ${K}_{1}(1270)$ resonance by using the chiral unitary approach to account for the final-state interactions between the pseudoscalar ($P$) and vector ($V$) mesons. The ${K}_{1}(1270)$ resonance is dynamically generated through these interactions in coupled channels and influences the shape of the invariant mass distributions under consideration. We show how these shapes are affect…
Harmonic Coupling of the Red Noise in X‐Ray Pulsars
1997
The power spectra of X-ray pulsars often show the presence of a red-noise component. This noise is produced by aperiodic variability believed to be associated with instabilities that seem to occur in accretion flows onto compact objects. In this paper we discuss how, independently of the details of the physical processes that generate these instabilities, a careful analysis of the power spectra can furnish some constraints on the distance from the stellar surface at which the sudden energy release associated with the instabilities occurs. In particular, any aperiodic variability coming from the accretion flow funneled toward the magnetic poles should be modulated at the pulsar spin period (…
A walk-free centroid method for lifetime measurements with pulsed beams
1978
Abstract A delayed-coincidence lifetime measurement method based on a comparison of walk-free centroids of time spectra is presented. The time is measured between the cyclotron rf signal and the pulse from a plastic scintillation detector followed by a fixed energy selection. The events to be time-analyzed are selected from the associated charge-particle spectrum of a silicon detector which is operated in coincidence with the scintillator, i.e. independently of the formation of the signal containing the time information. With this technique, with the micropulse fwhm of typically 500 to 700 ps, half-lives down to the 10 ps region can be measured. The following half-lives are obtained with th…
Some spectral properties for operators acting on Rigged Hilbert spaces
2015
Operators on Rigged Hilbert spaces have been considered from the 80s of the 20th century on as good ones for describing several physical models whose observable set didn’t turn out to be a C∗-algebra.A notion of resolvent set for an operator acting in a rigged Hilbert space \(\mathcal{D}\subset \mathcal{H}\subset \mathcal{D}^{\times }\) is proposed. This set depends on a family of intermediate locally convex spaces living between \(\mathcal{D}\) and \(\mathcal{D}^{\times }\), called interspaces. Some properties of the resolvent set and of the corresponding multivalued resolvent function are derived and some examples are discussed.
A Study of the Correlation between the Amplification of the Fe Kα Line and the X‐Ray Continuum of Quasars due to Microlensing
2006
The observed enhancement of the Fe Kα line in three gravitationally lensed QSOs (MG J0414+0534, QSO 2237+0305, and H1413+117) is interpreted in terms of microlensing, even when equivalent X-ray continuum amplification is not observed. In order to interpret these observations, first we studied the effects of microlensing on quasar spectra produced by a straight fold caustic crossing over a standard relativistic accretion disk. The disk emission was analyzed using the ray-tracing method, considering Schwarzschild and Kerr metrics. When the emission is separated into two regions (an inner disk corresponding to the Fe Kα line and an outer annulus corresponding to the continuum, or vice versa), …
Measuring Microlensing using Spectra of Multiply Lensed Quasars
2012
We report on a program of spectroscopic observations of gravitationally-lensed QSOs with multiple images. We seek to establish whether microlensing is occurring in each QSO image using only single-epoch observations. We calculate flux ratios for the cores of emission lines in image pairs to set a baseline for no microlensing. The offset of the continuum flux ratios relative to this baseline yields the microlensing magnification free from extinction, as extinction affects the continuum and the lines equally. When we find chromatic microlensing, we attempt to constrain the size of the QSO accretion disk. SDSSJ1004+4112 and HE1104-1805 show chromatic microlensing with amplitudes $0.2< |\Delta …
Generalized Bloch spheres form-qubit states
2006
m-Qubit states are imbedded in $\mathfrak{Cl}_{2^m}$ Clifford algebras. Their probability spectra then depend on $O(2m)$ or $O(2m+1)$ invariants. Parameter domains for $O(2m(+1))-$ vector and tensor configurations, generalizing the notion of a Bloch sphere, are derived.