Search results for "Spectral"
showing 10 items of 3116 documents
η′-Nucleus optical potential and possible η′ bound states
2012
Abstract Starting from a recent model of the η ′ N interaction, we evaluate the η ′ -nucleus optical potential, including the contribution of lowest order in density, t ρ / 2 m η ′ , together with the second-order terms accounting for η ′ absorption by two nucleons. We also calculate the formation cross section of the η ′ bound states from ( π + , p ) reactions on nuclei. The η ′ -nucleus potential suffers from uncertainties tied to the poorly known η ′ N interaction, which can be partially constrained by the experimental modulus of the η ′ N scattering length and/or the recently measured transparency ratios in η ′ nuclear photoproduction. Assuming an attractive interaction and taking the c…
Monte Carlo simulation of alpha spectra in low-geometry measurements
1994
Abstract Monte Carlo simulation of alpha spectra obtained with semiconductor detectors in low-geometry has been developed. The proposed method reproduces adequately experimental spectra of alpha emitters by taking into account the energy losses and trajectory changes of alpha particles as consequences of their interactions in the source, backing and detector.
Properties of the 13/2+ isomeric decay in201Hg
1990
The isomeric decay of theT1/2=94 us isomeric state in201Hg was studied in beam via the reaction198Pt(α, n). Gamma-ray and conversion-electron spectra were recorded. From the conversion coefficients, the multipolarities of the two depopulating transitions were determined to beM 2 + 10%E 3 andE 2, respectively. These assignments give the depopulating transitions to be 13/2+ → 9/2− and 9/2− → 5/2−, and these thus substantiate the previous suggestion that the isomeric state hasJπ=13/2+. For the 13/2+ → 9/2−M 2 transition a detailed study ofE 3 andM 4 admixed amplitudes was done. The microscopic properties of the 13/2+ and 9/2− states are discussed, and a comparison to the corresponding ones in1…
Collectivity ofPo196at low spin
2009
Absolute electromagnetic transition probabilities in $^{196}\mathrm{Po}$ have been measured using the recoil distance Doppler-shift technique. The lifetimes of the three lowest yrast states in $^{196}\mathrm{Po}$ were extracted from singles \ensuremath{\gamma}-ray spectra by using the recoil-decay tagging method. In addition, configuration mixing calculations of angular momentum projected mean-field states have been carried out for $^{196}\mathrm{Po}$. The present study sheds light on the onset of collectivity and mixing of competing structures in neutron-deficient Po nuclei.
Level structure of170Er observed in the decay of the 2.76 min170Ho
1978
TheΒ−-decay of the longer-lived170Ho isomer produced through the170Er(n, p)170Ho reaction has been investigated by using a versastile detector and coincidence equipment. The half-life andΒ−-decay energy were determined to beT1/2=2.76±0.05 min andQβ =3.85±0.15 MeV, respectively. In addition to the ground state band and some higher energy levels, the proposed level scheme of170Er contains 11 states between 1.0 and 1.6 MeV (6 new ones), which are connected mutually by previously unknown low-energy transitions. Spin and/or parity assignments based mainly on coincidence data and multipolarity determinations are suggested for most of these states. By using systematic considerations and the nuclea…
Ground-state spins and moments of72,74,76,78Ga nuclei
2011
Laser spectroscopy was performed on the ${}^{72,74,76,78}$Ga isotopes at On-Line Isotope Mass Separator (ISOLDE) facility, CERN. Ground-state nuclear spins and moments were extracted from the measured hyperfine spectra. The results are compared to shell-model calculations, which provide a detailed probe of the nuclear wave function. The spin is established from the shape of the hyperfine structure and the parity inferred from a comparison of shell-model calculations with the measured nuclear moments. The ground states of ${}^{76,78}$Ga are both assigned a spin and parity of ${I}^{\ensuremath{\pi}}={2}^{\ensuremath{-}}$, while ${}^{74}$Ga is tentatively assigned as ${I}^{\ensuremath{\pi}}={3…
A two-detector spectrometer for measurements of Doppler broadened positron annihilation spectra
2004
Abstract A two-detector spectrometer for measurements of Doppler broadened positron annihilation spectra has been constructed and tested. The energy difference of the annihilation quanta is measured in the analogue, not in the digital manner. The peak to background ratio in the measured spectra is of the order of 10 6 , the FWHM representing the energy resolution, equals to 1.1 keV , thus enabling the very subtle physical effects to be revealed. Some information on electronic structure of the investigated 3-d metals (Ti, V, Cr, Fe, Ni, Cu and Zn) has been determined using this spectrometer. It has been shown that the apparatus permits to detect the impurity-vacancy pairs in dilute nickel al…
BeppoSAX observations of EXO 0531-66 in outburst and X persei
1999
Abstract We report temporal and spectral analysis of two Be/X-ray systems observed by the BeppoSAX NFI. EXO 0531-66 was in outburst during the BeppoSAX observation: it is not a well known source because it is not detectable during the low states and the outbursts are unforeseeable and at temporal distances of years. X Persei is a well known source, but the band spectrum, obtained for the first time from the BeppoSAX observation, revealed an unexpected complexity.
12C(p,p′) scattering measurement at forward angles
2006
Experimental method of measuring inelastic proton scattering with high-resolution at forward angles including zero degrees has been developed. An energy resolution of 20 keV and a scattering angle resolution of 0.5 degrees have been achieved as well as low background condition and a reliable background subtraction method. The experimental technique was applied to the 12 C (p,p′) reaction for studying the property of the second 0+ state at 7.7 MeV and a broad bump around Ex~10 MeV , where the presence of a 2+ state was reported from the 12 C (α,α′) measurement. Preliminary spectra and angular distributions are shown.
CMB anisotropies: cosmic confusion and polarization
2001
Abstract Some physical effects producing Cosmic Microwave Background (CMB) anisotropies are briefly described. The CMB angular power spectrum is calculated -in appropriate cases- with the essential aim of estimating and comparing the effects produced by reionization and gravitational waves; thus a problem of Cosmic Confusion is pointed out. Accurate measurements of the CMB polarization could solve this problem in future. Some comments about the PLANCK mission —ESA project for anisotropy detection— are given.