Search results for "Isobaric process"
showing 10 items of 99 documents
Total absorption study of theβdecay of102,104,105Tc
2013
The $\ensuremath{\beta}$-feeding probabilities for three important contributors to the decay heat in nuclear reactors, namely ${}^{102,104,105}$Tc, have been measured using the total absorption spectroscopy technique. For the measurements, sources of very high isobaric purity have been obtained using a Penning trap (JYFLTRAP). A detailed description of the data analysis is given and the results are compared with high-resolution measurements and theoretical calculations.
Pressure and temperature dependence of the band-gap in CdTe
2003
In this paper we report on isothermal compression measurements (up to 5 GPa and 500 K) of the optical absorption edge of 1 μm epitaxial layers of CdTe growth by metalorganic chemical vapor deposition (MOCVD) on GaS substrates. The isothermal blue shift under pressure of the direct energy gap (Γ v 15 → Γ c 1 ) in the zinc-blende phase is about 7.1 × 10 -2 eV GPa -1 and is found to be independent of temperature within the experimental errors. The isobaric red shift in the stability range of the zinc-blende phase is about -3.76 × 10 -4 eV K -1 . Regarding the phase transitions, no discontinuity in the energy gap has been found in the narrow pressure range where the cinnabar phase can be presen…
Ellipsometric studies of behenic acid at the air-water interface
1991
The rich phase behaviour of monolayers of behenic acid (=docosanoic acid) has been analyzed by null ellipsometry in isothermic and isobaric measurements. By using structural data known from x-ray measurements the anisotropy and refractive indices in the vicinity of the S-CS phase transition have been calculated with a minimum of model assumptions. The calculated values are: nsx=1.47. ncsx=1.48. nsz=1.54. ncsz=1.55. and anisotropy γ=nx/nz ≈0.95. It is also shown that ellipsometry is a very sensitive and convenient method of detecting phase transitions. Its value for quantifying the roughness of the monolayer in the close vicinity of phase transitions due to thickness and density fluctuations…
Low-lying level structure of Cu56 and its implications for the rp process
2017
The low-lying energy levels of proton-rich Cu56 have been extracted using in-beam γ-ray spectroscopy with the state-of-the-art γ-ray tracking array GRETINA in conjunction with the S800 spectrograph at the National Superconducting Cyclotron Laboratory at Michigan State University. Excited states in Cu56 serve as resonances in the Ni55(p,γ)Cu56 reaction, which is a part of the rp process in type-I x-ray bursts. To resolve existing ambiguities in the reaction Q value, a more localized isobaric multiplet mass equation (IMME) fit is used, resulting in Q=639±82 keV. We derive the first experimentally constrained thermonuclear reaction rate for Ni55(p,γ)Cu56. We find that, with this new rate, the …
Statistical analysis ofβdecays and the effective value ofgAin the proton-neutron quasiparticle random-phase approximation framework
2016
We perform a Markov chain Monte Carlo (MCMC) statistical analysis of a number of measured ground-state-to-ground-state single ${\ensuremath{\beta}}^{+}$/electron-capture and ${\ensuremath{\beta}}^{\ensuremath{-}}$ decays in the nuclear mass range of $A=62--142$. The corresponding experimental comparative half-lives ($logft$ values) are compared with the theoretical ones obtained by the use of the proton-neutron quasiparticle random-phase approximation $(pn\mathrm{QRPA})$ with $G$-matrix-based effective interactions. The MCMC analysis is performed separately for 47 isobaric triplets and 28 more extended isobaric chains of nuclei to extract values and uncertainties for the effective axial-vec…
Emission of fragments in Ca+Ca reaction at 25 MeV/nucleon
2013
We discuss experimental data concerning 40,48Ca+ 40,48Ca reactions at 25 MeV/nucleon; the 4π multi-detector Chimera has been used as detection device. Effects that can be attributed to the neutron to proton ratios (N/Z) degree of freedom have been investigated. From the analysis of experimental data it seems that the neutron richness of the interacting system plays an important role on the evolution of fusion-like sources formed in semi-central collisions. In particular, it is observed that the larger is the neutron content and the larger is the emission of heavy residues. Experimental data have been compared with CoMD-II model calculations; a moderately stiff symmetry energy should be used…
Isospin dependence of electromagnetic transition strengths among an isobaric triplet
2019
*Aydın, Sezgin ( Aksaray, Yazar )
The β2p decay mechanism of Ar
2000
We have measured the beta-decay of Ar-31 with a high granularity setup sensitive to multiparticle decay branches. Two-proton emission is observed from the isobaric analog state in Cl-31 to the four lowest states in P-29 and furthermore from a large number of states fed in Gamow-Teller transitions. The mechanism of two-proton emission is studied via energy and angular correlations between the two protons. In all cases the mechanism is found to be sequential yielding information about states in S-30 up to 8 MeV excitation energy. Improved data on the beta-delayed one-proton branches together with the two-proton data provide precise information about the beta-strength distribution up to 15 MeV…
Measurement of the IAS resonance strength in 23Mg
2000
Abstract Beta decay of 23 Al to excited states in 23 Mg has been studied using low-energy proton and high-energy gamma-ray detection combined with ion-guide-based on-line mass separation. For the first time, a T =3/2 isobaric analogue state, at 7801(2) keV, was observed to decay by both proton and gamma emission, with a proton branching of 0.17(8)%. The deduced resonance strength ωγ =2.2(10) meV is in agreement with upper limits reported from 22 Na(p, γ ) reaction studies. Shell-model calculations are incorporated.
Selective laser ionization of N≥82 indium isotopes: The new r-process nuclide 135In
2002
Production yields and beta-decay half-lives of very neutron-rich indium isotopes were determined at CERN/ISOLDE using isobaric selectivity of a resonance-ionization laser ion-source. Beta-delayed neutron multiscaling measurements have yielded improved half-lives for 206(6)~ms $^{132}$In, 165(3)~ms $^{133}$In and 141(5)~ms $^{134}$In. With 92(10)~ms $^{135}$In, a new r-process nuclide has been identified which acts as an important `waiting-point' in the In isotopic chain for neutron densities in the range n$_n \simeq 10^{24}$--10$^{26}$ n/cm$^3$, where the r-matter flow has already passed the ${\rm A} \simeq 130$ abundance-peak region.