Predicting access to persistent objects through static code analysis

In this paper, we present a fully-automatic, high-accuracy approach to predict access to persistent objects through static code analysis of object-oriented applications. The most widely-used previous technique uses a simple heuristic to make the predictions while approaches that offer higher accuracy are based on monitoring application execution. These approaches add a non-negligible overhead to the application’s execution time and/or consume a considerable amount of memory. By contrast, we demonstrate in our experimental study that our proposed approach offers better accuracy than the most common technique used to predict access to persistent objects, and makes the predictions farther in advance, without performing any analysis during application executionThis work has been supported by the European Union’s Horizon 2020 research and innovation program (grant H2020-MSCA-ITN-2014-642963), the Spanish Government (grant SEV2015-0493 of the Severo Ochoa Program), the Spanish Ministry of Science and Innovation (contract TIN2015-65316) and Generalitat de Catalunya (contract 2014-SGR-1051). The authors would also like to thank Alex Barceló for his feedback on the formalization included in this paper.Peer ReviewedPostprint (author's final draft

Lifetime measurements of the low-lying excited states of ²⁰⁸Po

In this study we present the preliminary results about the lifetimes of the 2₂⁺, 4₁⁺ states of ²⁰⁸Po and the upper limit of the lifetime of the 2₁⁺ state. For measuring the lifetimes of the 2₁⁺ and 4₁⁺ states the Recoil Distance Doppler Shift (RDDS) method and for the lifetime of the 2₂⁺ state the Doppler Shift Attenuation method (DSAM) were used. The resulting absolute transition strength B(M1 ; 2₂⁺ → 2₁⁺) ≥ 0.122(20) μN² reveals the predominant isovector nature of the 2₂⁺ state of ²⁰⁸Po

Lifetime measurements of the low-lying excited states of ²⁰⁸Po

In this study we present the preliminary results about the lifetimes of the 2₂⁺, 4₁⁺ states of ²⁰⁸Po and the upper limit of the lifetime of the 2₁⁺ state. For measuring the lifetimes of the 2₁⁺ and 4₁⁺ states the Recoil Distance Doppler Shift (RDDS) method and for the lifetime of the 2₂⁺ state the Doppler Shift Attenuation method (DSAM) were used. The resulting absolute transition strength B(M1 ; 2₂⁺ → 2₁⁺) ≥ 0.122(20) μN² reveals the predominant isovector nature of the 2₂⁺ state of ²⁰⁸Po

Lifetime measurements in Nb99 and Zr99 : Investigation of shape coexistence

The ≈100 mass region is of special interest due to a rapid shape transition, observed by going from neutron number 58 to 60, especially pronounced in the Zr isotopes, where 98Zr is weakly and 100Zr is strongly deformed. To further examine this intricate phenomenon, in this work lifetimes of low-lying excited states in the nuclei 99Zr and 99Nb were determined using fast-timing techniques and an experimental setup consisting of four LaBr3⁢(Ce) detectors. Neutron rich =99 fragments were produced in neutron induced fission and separated by the spectrometer LOHENGRIN at the Institut Laue-Langevin in Grenoble, France. Experimental values are compared to two different calculations in the framework of the interacting boson-fermion model and discussed in the context of shape coexistence

Tests of collectivity in Zr-98 by absolute transition rates

Lifetimes of low-spin excited states in Zr-98 were measured using the recoil-distance Doppler-shift technique , and the Doppler-shift attenuation method. The nucleus of interest was populated in a( 96)zr(O-18, O-16) Zr-98 two- neutron transfer reaction at the Cologne FN Tandem accelerator. Lifetimes of six low-spin excited states, of which four are unknown, were measured. The deduced B(E2) values were compared with Monte Carlo shell model and interacting boson model with configuration mixing calculations. Both approaches reproduce well most of the data but leave challenging questions regarding the structure of some low-lying states

Lifetime measurements in Pt-182 using gamma-gamma fast-timing

The level lifetimes of the 2(1)(+) and 4(1)(+) states in Pt-182 have been re-measured employing the gamma-gamma fast-timing technique using fast LaBr3(Ce) scintillators. Excited states in the nucleus of interest were populated by the fusion-evaporation reaction Yb-170(O-16, 4n)Pt-182 at a beam energy of 87 MeV provided by the FN Tandem accelerator of the University of Cologne. The lifetime of the 2(1)(+) state was re-measured with high accuracy to be tau = 563(12) ps and resolves inconsistencies from previous measurements. Experimental results are compared to theoretical calculations in the framework of the sd-IBM with and without configuration mixing

Lifetime measurements of Er-162: Evolution of collectivity in the rare-earth region

Lifetimes of low-lying yrast states in Er-162 are measured using the electronic gamma-gamma fast-timing technique. Excited states were populated in a Sm-154(C-12, (4)n)Er-162 fusion-evaporation reaction and gamma rays were detected in a combined setup of high purity germanium and LaBr3(Ce) scintillation detectors. The lifetimes of the 4(1)(+) and 6(1)(+) states are determined for the first time and the lifetimes of the 2(1)(+) and 7- states are remeasured with higher precision. Reduced transition probabilities are extracted and well reproduced by theoretical calculations in the framework of the confined beta soft model and the interacting boson model

Lifetime determination in Hg-190,Hg-192,Hg-194,Hg-196 via gamma-gamma fast-timing spectroscopy

Lifetimes of 2(1)(+) and 4(1)(+) states in Hg-190,Hg-192,Hg-194,Hg-196 and of some negative parity band members were measured using the gamma-gamma fast-timing technique with a high-purity germanium and LaBr3(Ce) detector array. The excited states were populated via fusion-evaporation reactions using the Tandem Van de Graaff accelerator of the Institute of Nuclear Physics in Cologne, Germany. The derived reduced transition probabilities of the 2(1)(+)-> 0(1)(+) and 4(1)(+) -> 2(l)(+) transitions are discussed in the framework of the interacting boson approximation with two models using configuration mixing: a phenomenological one and a microscopical one. Both models describe the observed quantities of the nuclei within the experimental uncertainties