βdecay of the 21/2^+ isomer in ^<93>Mo and level structure of ^<93>Nb

The γ rays associated with β decay of the 21/2^+ isomer in ^Mo (Ex=2.425 MeV, T_=6.85 h) were measured with a selective sensitivity to long-lived isomer decays. A new 1262-keV transition was found in the γ-γ coincidence measurement, and it was attributed to a transition in ^Nb, which is the daughter nucleus of the β decay of the ^Mo isomer, from the 2.753- to the 1.491-MeV levels. Accurate γ-ray intensity balances have determined the β-decay intensity from the ^Mo isomer to the 2.753-MeV level in ^Nb and placed no appreciable intensity for the previously reported β-decay branching to the 2.180-MeV level, for which a recent in-beam γ-ray experiment assigned to be I^π = 17/2^-. Based on the γ-ray intensities from the 2.753-MeV level, spin-parity assignment of this level was revised from 21/2^+ to 19/2^+. The observed β-decay intensity and the spin-parity assignment were explained by the jj-coupling shell model calculations

β decay of 129Cd and excited states in 129In

J. Taprogge et al.; 11 pags.; 8 figs.; 2 tabs.; PACS number(s): 23.20.Lv, 23.40.−s, 21.60.Cs, 27.60.+j©2015 American Physical Society. The β decay of 129Cd, produced in the relativistic fission of a 238U beam, was experimentally studied at the RIBF facility at the RIKEN Nishina Center. From the γ radiation emitted after the β decays, a level scheme of 129In was established comprising 31 excited states and 69 γ -ray transitions. The experimentally determined level energies are compared to state-of-the-art shell-model calculations. The half-lives of the two β-decaying states in 129Cd were deduced and the β feeding to excited states in 129In were analyzed. It is found that, as in most cases in the Z < 50, N 82 region, both decays are dominated by the ν0g7/2 → π0g9/2 Gamow–Teller transition, although the contribution of first-forbidden transitions cannot be neglected.This work was supported by the Spanish Ministerio de Ciencia e Innovacion under contracts FPA2009-13377-C02 and FPA2011-29854- C04, the Generalitat Valenciana (Spain) under grant PROMETEO/2010/101, the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. NRF-2012R1A1A1041763), the Priority Centers Research Program in Korea (2009-0093817), OTKA contract number K-100835, JSPS KAKENHI (Grant No. 25247045), the European Commission through the Marie Curie Actions call FP7-PEOPLE-2011-IEF under Contract No. 300096, the US Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357, the “RIKEN foreign research program,” and the German BMBF (No. 05P12RDCIA and 05P12RDNUP) and HIC for FAIR.Peer Reviewe

Structural evolution in the neutron-rich nuclei 106Zr and 108Zr

The low-lying states in 106Zr and 108Zr have been investigated by means of {\beta}-{\gamma} and isomer spectroscopy at the RI beam factory, respectively. A new isomer with a half-life of 620\pm150 ns has been identified in 108Zr. For the sequence of even-even Zr isotopes, the excitation energies of the first 2+ states reach a minimum at N = 64 and gradually increase as the neutron number increases up to N = 68, suggesting a deformed sub-shell closure at N = 64. The deformed ground state of 108Zr indicates that a spherical sub-shell gap predicted at N = 70 is not large enough to change the ground state of 108Zr to the spherical shape. The possibility of a tetrahedral shape isomer in 108Zr is also discussed.Comment: 10 pages, 3 figures, Accepted for publication in Phys. Rev. Let

β-Decay Half-Lives of 110 Neutron-Rich Nuclei across the N = 82 Shell Gap: Implications for the Mechanism and Universality of the Astrophysical r Process

G. Larusso et al.; 7 pags.; 5 figs.; 2 tabs.; PACS numbers: 23.40.-s, 26.30.Hj, 27.60.+j© 2015 American Physical Society. The β-decay half-lives of 110 neutron-rich isotopes of the elements from 37Rb to 50Sn were measured at the Radioactive Isotope Beam Factory. The 40 new half-lives follow robust systematics and highlight the persistence of shell effects. The new data have direct implications for r-process calculations and reinforce the notion that the second (A ≈ 130) and the rare-earth-element (A ≈ 160) abundance peaks may result from the freeze-out of an (n, γ) ⇄ (γ,n) equilibrium. In such an equilibrium, the new half-lives are important factors determining the abundance of rare-earth elements, and allow for a more reliable discussion of the r process universality. It is anticipated that universality may not extend to the elements Sn, Sb, I, and Cs, making the detection of these elements in metal-poor stars of the utmost importance to determine the exact conditions of individual r-process events.Part of the WAS3ABi was supported by the Rare Isotope Science Project which is funded by the Ministry of Education, Science, and Technology (MEST) and National Research Foundation (NRF) of Korea. This work was partially supported by KAKENHI (Grants No. 25247045, No. 2301752, and No. 25800130), the RIKEN Foreign Research Program, the Spanish Ministerio de Ciencia e Innovación (Contracts No. FPA2009-13377-C02 and No. FPA2011-29854-C04), the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, Contract No. DE-AC02-06CH11357, the NASA Grant No. NNX10AH78G, and the Hungarian Scientific Research Fund OTKA Contract No. K100835.Peer Reviewe

Study of High-Spin Structure in 151Er

Berdasarkan pengalaman di kelas V SDN 009 Pulau Kecamatan Bangkinang Seberang Kabupaten Kampar, penulis menemukan gejala-gejala atau fenomena khususnya pada pelajaran Ilmu Pengetahuan Alam, hal ini terlihat dari nilai rapor khususnya pada mata pelajaran Sains, dari 30 hanya 10 siswa atau 30% yang mencapai nilai Kriteria Ketuntasan Minimal (KKM) 65 yang ditetapkan sekolah. Adanya sebagian murid yang sulit memahami pelajaran yang disampaikan, hal ini terlihat dari hasil evaluasi yang dilaksanakan oleh guru hanya sebagian murid yang memperoleh nilai yang baik dan dapat mengerjakan soal dengan benar. Dan dari 30 orang murid hanya 30% dari jumlah keseluruhan murid yang dapat mengerjakan tugas atau latihan dengan benar dan sesuai dengan jadwal yang ditetapkan oleh guru. Penelitian ini bertujuan untuk mengetahui keberhasilan penerapan strategi pembelajaran rapat dewan kota dapat meningkatkan hasil belajar pada pelajaran Ilmu Pengetahuan Alam materi Sumber Daya Alam dan penggunaannya siswa kelas V SDN 009 Pulau. Penelitian ini dilakukan dalam dua siklus dan tiap siklus dilakukan dalam dua kali pertemuan. Agar penelitian tindakan kelas ini berhasil dengan baik tanpa hambatan yang mengganggu kelancaran penelitian, peneliti menyusun tahapantahapan yang dilalui dalam penelitian tindakan kelas, yaitu: 1) Perencanaan/persiapan tindakan, 2) Pelaksanaan tindakan, 3) Observasi, dan Refleksi. Hasil penelitian pada aktivitas guru siklus I Pertemuan pertama secara klasikal memperoleh skor 27 dengan kategori kurang sempurna dan pada pertemuan kedua memperoleh skor secara klasikal adalah 34 dengan kategori cukup sempurna. Sedangkan pada siklus II pertemuan pertama memperoleh skor secara klasikal adalah 42 dengan kategori sempurna dan pada pertemuan kedua meningkat dengan perolehan skor dengan kategori sangat sempurna. Aktivitas siswa pada siklus I pertemuan pertama memperoleh skor secara klasikal adalah 660 dengan kategori sangat rendah, dan pada pertemuan kedua memperoleh skor 864 dengan kategori rendah. Sedangkan pada siklus II pertemuan I memperoleh skor 1123 dengan kategori tinggi dan pada pertemuan kedua meningkat dengan memperoleh skor 1359 dengan kategori sangat tinggi. Berdasarkan sebelum tindakan hasil belajar siswa hanya mencapai rata-rata nilai 60 dengan kategori belum tuntas, pada siklus I hasil belajar siswa meningkat dengan rata-rata nilai 62 dengan kategori sedang, dan pada siklus II hasil belajar siswa mengalami peningkatan sangat memuaskan dengan perolehan rata-rata nilai 79 dengan kategori baik. Hal ini membuktikan bahwa melalui strategi pembelajaran rapat dewan kota dapat meningkatkan hasil belajar siswa khususnya pada mata pelajaran Ilmu Pengetahuan Alam Materi Sumber daya alam dan penggunaannya