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In this work, we apply relativistic impulse approximation (RIA) with a modern density functional PC-PK1 to systematically analyze the available experimental data at 40 < E p ≤ 200 MeV. The theoretical calculations successfully reproduce the numerous experimental data of the elastic-scattering cross sections and analyzing power for both even and odd nuclei in a wide range of mass number ( 12 ≤ A ≤ 232 ) and incident energies ( 40 < E p ≤ 200 MeV). Moreover, a strong correlation between the root-mean-square (rms) radius of the neutron distribution and the inverse of momentum transfer corresponding to the minimum of the cross section is demonstrated again. We have further confirmed the validity of RIA and the universality of the density functional PC-PK1. This work also provides a good basis to incorporate the ab-initio relativistic chiral force and the medium effect using G-matrix to the present RIA framework. [ABSTRACT FROM AUTHOR]

The recent advances in nuclear mass measurement have sparked discussions on the isospin-symmetry breaking reflected in the Coulomb displacement energy (CDE). The current data suggested that the regular phase of the odd–even staggering in CDE for the T = 1/2 mirror nuclei persists up to A = 67 and changes at A = 69. Shell-model calculations using the modern GXPF1A and JUN45 effective interactions with a proper treatment of the Coulomb and isospin-nonconserving forces cannot describe the observation. Inspired by recent work (Kaneko 2013 Phys. Rev. Lett.110 172505), we investigate the systematic behavior of CDE along the N = Z line up to the heaviest available masses. Starting from A ≈ 65, a systematic deviation is observed between the experimental data and the model estimations assuming the nucleus as a homogeneously charged sphere. Possibilities that may resolve the conflict between the experimental mass and theoretical expectations for the 69Br-region are discussed, and new mass experiments are called for. [ABSTRACT FROM AUTHOR]

An evident odd-even staggering (OES) in fragment cross sections has been experimentally observed in many fragmentation and spallation reactions. However, quantitative comparisons of this OES effect in different reaction systems are still scarce for neutron-rich nuclei near the neutron drip line. By employing a third-order difference formula, the magnitudes of this OES in extensive experimental cross sections are systematically investigated for many neutron-rich nuclei with (N-Z) from 1 to 23 over a broad range of atomic numbers (Z≈3-50). A comparison of these magnitude values extracted from fragment cross sections measured in different fragmentation and spallation reactions with a large variety of projectile-target combinations over a wide energy range reveals that the OES magnitude is almost independent of the projectile-target combinations and the projectile energy. The weighted average of these OES magnitudes derived from cross sections accurately measured in different reaction systems is adopted as the evaluation value of the OES magnitude. These evaluated OES magnitudes are recommended to be used in fragmentation and spallation models to improve their predictions for fragment cross sections. [ABSTRACT FROM AUTHOR]

Lifetime measurements of α-decaying highly charged ions have been performed in the experimental storage ring (CSRe) by applying the isochronous Schottky mass spectrometry. The fully ionized 49Cr and 53Fe ions were produced in projectile fragmentation of 58Ni primary beam and were stored in the CSRe tuned into the isochronous ion-optical mode. The new resonant Schottky detector was applied to monitor the intensities of stored uncooled 49Cr24+ and 53Fe26+ ions. The extracted half-lives T1/2(49Cr24+)=44.0(27) min and T1/2(53Fe26+)=8.47(19) min are in excellent agreement with the literature half-life values corrected for the disabled electron capture branchings. This is an important proof-of-principle step towards realizing the simultaneous mass and lifetime measurements on exotic nuclei at the future storage ring facilities. [ABSTRACT FROM AUTHOR]

Isochronous mass spectrometry was applied to measure isomeric yield ratios of fragmentation reaction products. This approach is complementary to conventional γ-ray spectroscopy in particular for measuring yield ratios for long-lived isomeric states. Isomeric yield ratios for the high-spin I=19/2ℏ states in the mirror nuclei 53Fe and 53Co are measured to study angular momentum population following the projectile fragmentation of 78Kr at energies of ~480A MeV on a beryllium target. The 19/2 state isomeric ratios of 53Fe produced from different projectiles in the literature have also been extracted as a function of mass number difference between projectile and fragment (mass loss). The results are compared to ABRABLA07 model calculations. The isomeric ratios of 53Fe produced using different projectiles suggest that the theory underestimates not only the previously reported dependence on the spin but also the dependence on the mass loss. [ABSTRACT FROM AUTHOR]

Fundamental properties of doubly-magic nuclei, such as radius and binding energy, play a key role in theoretical calculations. Reported matter radii of 16 O have a large discrepancy, especially for results obtained from interaction cross sections. To address this issue, the published small-angle differential cross sections of proton-nuclei elastic scattering in the energy region of 200–700 MeV were reanalyzed using the Glauber model. A precise matter radius of 2.554(20) fm for 16 O was extracted. The calculated neutron skin thicknesses of 16 O by different interactions do not obviously depend on the symmetry energy, and agree with our result. [ABSTRACT FROM AUTHOR]

Revolution frequency measurements of individual ions in storage rings require sophisticated timing detectors. One of common approaches for such detectors is the detection of secondary electrons released from a thin foil due to penetration of the stored ions. A new method based on the analysis of intensities of secondary electrons was developed which enables determination of the charge of each ion simultaneously with the measurement of its revolution frequency. Although the mass-over-charge ratios of 51Co27+ and 34Ar18+ ions are almost identical, and therefore, the ions cannot be resolved in a storage ring, by applying the new method the mass excess of the short-lived 51Co is determined for the first time to be ME(Co51)=-27342(48) keV. Shell-model calculations in the fp-shell nuclei compared to the new data indicate the need to include isospin-nonconserving forces. [ABSTRACT FROM AUTHOR]

Strong odd-even staggering (OES) of the yields of fragments, produced by fragmenting 78Kr projectiles, has been measured by employing the combination of an in-flight fragment separator and a storage ring. It is shown that the OES of fragment yields of Tz=-1/2 and Tz=1/2 mirror nuclei critically depends on both pairing and shell structure, especially at the closed shells Z = 20 and 28. A comparison of the relative OES of yields and of particle-emission threshold energies reveals unambiguously that the origin of the OES of fragment yields is mainly determined by the OES of the particle-emission threshold energies, which contain both pairing and shell effects. [ABSTRACT FROM AUTHOR]

The very first in-ring reaction experiment at the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR), namely proton elastic scattering on stable 58Ni nuclei, is presented. The circulating 58Ni19+ ions with an energy of 95 MeV/u were interacting repeatedly with an internal hydrogen gas target in the experimental storage ring (CSRe). Low-energy proton recoils from the elastic collisions were measured with an ultra-high vacuum compatible silicon-strip detector. Deduced differential cross sections were normalized by measuring k-shell x rays from 58Ni19+ projectiles due to the 58Ni19+-H2 ionization collisions. Compared to the experimental cross sections, a good agreement has been achieved with the theoretical predictions in the measured region, which were obtained by using the global phenomenological optical model potentials. Our results enable new research opportunities for optical model potential studies on exotic nuclides by using the in-ring reaction setup at the HIRFL-CSR facility. [ABSTRACT FROM AUTHOR]

The longitudinal momentum distributions of 7Be fragments in the breakup of 8B on a carbon target have been measured at 36 MeV/u. The different mechanisms have been distinguished by coincidence measurements. The longitudinal momentum distributions of 7Be fragments from both the stripping and the diffraction mechanisms are consistent with the results of noneikonal calculations and CDCC calculations. The full widths at half maximum of the longitudinal momentum distributions are 124 ± 17 and 92 ± 7 MeV/c for the stripping and diffraction components, respectively. The comparison with the different model calculations is discussed. It is crucial to separate the different reaction mechanisms experimentally to benchmark nuclear reaction theories. [ABSTRACT FROM AUTHOR]

Isochronous mass spectrometry has been applied to neutron-deficient 58Ni projectile fragments at the HIRFL-CSR facility in Lanzhou, China. Masses of a series of short-lived Tz = -3/2 nuclides including 41Ti, 45Cr, 49Fe, and 53Ni have been measured with a precision of 20-40 keV. The new data enable us to test for the first time the isobaric multiplet mass equation (IMME) in fp-shell nuclei. We observe that the IMME is inconsistent with the generally accepted quadratic form for the A - 53, T = 3/2 quartet. We perform full space shell model calculations and compare them with the new experimental results. [ABSTRACT FROM AUTHOR]

With the commissioning of the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR), a pilot experiment operating the CSRe in isochronous mode to test the power of HIRFL-CSR for measuring the mass of the short-lived nucleus was performed in December of 2007. The transition point γt of CSRe in isochronous mode is 1.395 which corresponds to the energy about 368 MeV/u for the ions with atomic number-to-charge ratio A/q = 2. The fragments with A/q = 2 of 36Ar were injected into CSRe and their revolution frequencies were measured with a fast time pick-up detector with a thin foil in the circulating path of the ions. A mass resolution of better than 105 for m/Δm was achieved. [ABSTRACT FROM AUTHOR]

The status of the HIRFL (Heavy Ion Facility in Lanzhou) – Cooler Storage Ring (CSR) at the IMP is reported. The main physics goals at the HIRFL-CSR are the researches on nuclear structure and decay property, EOS of nuclear matter, hadron physics, highly charged atomic physics, high energy density physics, nuclear astrophysics, and applications for cancer therapy, space industries, materials and biology sciences. The HIRFL-CSR is the first ion cooler-storage-ring system in China, which consists of a main ring (CSRm), an experimental ring (CSRe) and a radioactive beam line (RIBLL2). The two existing cyclotrons SFC (K = 70) and SSC (K = 450) are used as its injectors. The 7 MeV/u 12C6+ ions were stored successfully in CSRm with the stripping injection in January 2006. After that, realized were the accelerations of 12C6+, 36Ar18+, 78Kr28+ and 129Xe27+ ions with energies of 1 GeV/u, 1 GeV/u, 450 MeV/u and 235 MeV/u, respectively, including accumulation, electron cooling and acceleration. In 2008, the first two isochronous mass measurement experiments with the primary beams of 36Ar18+ and 78Kr28+ were performed at CSRe with the Δp/p ~ 10-5. [ABSTRACT FROM AUTHOR]

Two generic methods based on frequentism and Bayesianism are presented in this work aiming to adequately estimate decay lifetimes from measured data, while accounting for restricted observation times in the measurements. All the experimental scenarios that can possibly arise from the observation constraints are treated systematically and formulas are derived. The methods are then tested against the decay data of bare isomeric 94mRu44+, which were measured using isochronous mass spectrometry with a timing detector at the CSRe in Lanzhou, China. Applying both methods in three distinct scenarios yields six different but consistent lifetime estimates. The deduced values are all in good agreement with a prediction based on the neutral-atom value modified to take the absence of internal conversion into account. Potential applications of such methods are discussed. [ABSTRACT FROM AUTHOR]

Masses of 52g,52mCo were measured for the first time with an accuracy of ~10 keV, an unprecedented precision reached for short-lived nuclei in the isochronous mass spectrometry. Combining our results with the previous β−γ measurements of 52Ni, the T=2, Jπ=0+ isobaric analog state (IAS) in 52Co was newly assigned, questioning the conventional identification of IASs from the β-delayed proton emissions. Using our energy of the IAS in 52Co, the masses of the T=2 multiplet fit well into the isobaric multiplet mass equation. We find that the IAS in 52Co decays predominantly via γ transitions while the proton emission is negligibly small. According to our large-scale shell model calculations, this phenomenon has been interpreted to be due to very low isospin mixing in the IAS. [ABSTRACT FROM AUTHOR]