Discovery of the New Isotope^(251)Lr

The products of the^(203,205)Ti(^(50)Ti,2n)fusion-evaporation reactions were studied by using the recently commissioned Argonne Gas-Filled Analyzer(AGFA)at Argonne National Laboratory.

Shape Coexistence in Neutron-De cient Nuclei with Z-82,N-104

Neutron-de cient nuclei around mid-shell at N-104 in the lead region provide many cases of shape coexistence and shape isomers^([1,2]).In order to study shape coexistence in this region,prompt and delayed-ray spectroscopy of the^(187)Pb,^(183)Hg,^(188)Bi and^(188)Po nuclei produced by the fusion-evaporation reaction^(50)Cr+^(142)Nd→192Po^(*)has been performed at the Argonne Gas-Filled Analyzer.

2-4 AME2016 Atomic Mass Evaluation

As a fundamental property of nuclei,atomic masses are widely used in many domains of science and engineering.A reliable atomic mass table derived from the experimental data,where the atomic masses and the relevant experi-mental information can be found conveniently,is in high demand by the research community.To meet the demands,the Atomic Mass Evaluation(AME)was initiated in 1950's and a series of AME mass tables have been published ever since.Currently the AME serves the research community by providing the most reliable and comprehensive information related to the atomic masses.The new atomic mass evaluation AME2016 was published in the March issue of Chinese Physics C as two com-plementary papers[1;2].

The NUBASE2020 evaluation of nuclear physics properties

The NUBASE2020 evaluation contains the recommended values of the main nuclear physics properties for all nuclei in their ground and excited,isomeric(T1/2≥100 ns)states.It encompasses all experimental data published in primary(journal articles)and secondary(mainly laboratory reports and conference proceedings)references,together with the corresponding bibliographical information.In cases where no experimental data were available for a particular nuclide,trends in the behavior of specific properties in neighboring nuclei were examined and estimated values are proposed.Evaluation procedures and policies that were used during the development of this evaluated nuclear data library are presented,together with a detailed table of recommended values and their uncertainties.

The Ame2020 atomic mass evaluation(II).Tables,graphs and references

This is the second part of the new evaluation of atomic masses,Ame2020.Using least-squares adjustments to all evaluated and accepted experimental data,described in Part I,we derived tables with numerical values and graphs which supersede those given in Ame2016.The first table presents the recommended atomic mass values and their uncertainties.It is followed by a table of the influences of data on primary nuclides,a table of various reaction and decay energies,and finally,a series of graphs of separation and decay energies.The last section of this paper provides all input data references that were used in the Ame2020 and the Nubase2020 evaluations.

The Ame2020 atomic mass evaluation (I). Evaluation of input data, and adjustment procedures

This is the first of two articles(Part I and Part II)that presents the results of the new atomic mass evaluation,Ame2020.It includes complete information on the experimental input data that were used to derive the tables of recommended values which are given in Part II.This article describes the evaluation philosophy and procedures that were implemented in the selection of specific nuclear reaction,decay and mass-spectrometric data which were used in a least-squares fit adjustment in order to determine the recommended mass values and their uncertainties.All input data,including both the accepted and rejected ones,are tabulated and compared with the adjusted values obtained from the least-squares fit analysis.Differences with the previous Ame2016 evaluation are discussed and specific examples are presented for several nuclides that may be of interest to Ame users.

The AME2012 atomic mass evaluation(Ⅰ).Evaluation of input data,adjustment procedures

This paper is the second part of the new evaluation of atomic masses, AME2012. From the results of a leastsquares calculation, described in Part I, for all accepted experimental data, we derive here tables and graphs to replace those of AME2003. The first table lists atomic masses. It is followed by a table of the influences of data on primary nuclides, a table of separation energies and reaction energies, and finally, a series of graphs of separation and decay energies. The last section in this paper lists all references to the input data used in Part I of this AME2012 and also to the data included in the NUBASE2012 evaluation （first paper in this issue）.

The AME2012 atomic mass evaluation(Ⅱ).Tables,graphs and references

This paper is the first of two articles （Part I and Part II） that presents the results of the new atomic mass evaluation, AME2012. It includes complete information on the experimental input data （including not used and rejected ones）, as well as details on the evaluation procedures used to derive the tables with recommended values given in the second part. This article describes the evaluation philosophy and procedures that were implemented in the selection of specific nuclear reaction, decay and mass-spectrometer results. These input values were entered in the least-squares adjustment procedure for determining the best values for the atomic masses and their uncertainties. Calculation procedures and particularities of the AME are then described. All accepted and rejected data, including outweighed ones, are presented in a tabular format and compared with the adjusted values （obtained using the adjustment procedure）. Differences with the previous AME2003 evaluation are also discussed and specific information is presented for several cases that may be of interest to various AME users. The second AME2012 article, the last one in this issue, gives a table with recommended values of atomic masses, as well as tables and graphs of derived quantifies, along with the list of references used in both this AME2012 evaluation and the NUBASE2012 one （the first paper in this issue）.

The NUBASE2012 evaluation of nuclear properties

This paper presents the NUBASE2012 evaluation that contains the recommended values for nuclear and decay properties of nuclides in their ground and excited isomeric （T1/2≥ 100 ns） states. All nuclides for which some experimental information is known are considered. NUBASE2012 covers all up to date experimental data published in primary （journal articles） and secondary （mainly laboratory reports and conference proceedings） references, together with the corresponding bibliographical information. During the development of NUBASE2012, the data available in the ＂Evaluated Nuclear Structure Data File＂ （ENSDF） database were consulted, and critically assessed of their validity and completeness. Furthermore, a large amount of new and somewhat older experimental results that were missing in ENSDF were compiled, evaluated and included in NUI3ASE2012. The atomic mass values were taken from the ＂Atomic Mass Evaluation＂ （AME2012, second and third parts of the present issue）. In cases where no experimental data were available for a particular nuclide, trends in the behavior of specific properties in neighboring nuclei （TNN） were examined. This approach allowed to estimate, whenever possible, values for a range of properties, and are labeled in NUBASE2012 as ＂non-experimental＂ （flagged ＂#＂）. Evaluation procedures and policies that were used during the development of this database are presented, together with a detailed table of recommended values and their uncertainties.