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Transition Quadrupole Momens

Member of the US Nuclear Data Program. Transition Quadrupole Momens. This is a joint report with B. Singh (McMaster University) following action item #34 from the 16 th NSDD meeting in McMaster. Would like to acknowledge contributions from J. Tuli & T. Burrows (BNL) & C. Baglin (LBNL).

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Transition Quadrupole Momens

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  1. Member of the US Nuclear Data Program Transition Quadrupole Momens This is a joint report with B. Singh (McMaster University) following action item #34 from the 16th NSDD meeting in McMaster Would like to acknowledge contributions from J. Tuli & T. Burrows (BNL) & C. Baglin (LBNL) Filip G. Kondev1 & Balraj Singh2 1Nuclear Engineering Division, ANL 2McMaster University, Canada This topic is relevant mostly to the high-spin physics community– many such data in the last 10 years - should have been considered several years ago! 17th Meeting of the NSDD Network, St. Petersburg, Russia, 2007

  2. Transition Quadrupole Moment (measured) (rotational model) transition quadrupole moment • What do we need to know? • the level scheme • Pg, Eg & t Supported by the Office of Nuclear Physics, US DOE

  3. Lifetime of excited states 1 ns – 1ps < 1ps Others: • Direct width measurements • Inelastic electron scattering • Blocking technique • Mossbauer technique Supported by the Office of Nuclear Physics, US DOE

  4. DSAM Method • thin target (where reaction takes place) backed by high Z material to stop the recoils – the stopping powers govern this process in the ~ps time scale – act as a “clock” • emitted g-rays expire Doppler effect where the line-shape profile depends on nuclear lifetime • short lifetime - full shift, but long lifetime - no shift Supported by the Office of Nuclear Physics, US DOE

  5. DSAM Line-shape Technique SF SF SF SF velocity histories (depend on the lifetime) are converted into line-shapes, as seen by the individual detectors (after correcting for detector’s geometry and efficiency

  6. DSAM Centroid-shift Technique SF SF SF SF F.G. Kondev et al., Phys. Rev. C60 (1999) fit with a single Qt value for the whole band

  7. Modeling of the side feeding

  8. DSAM Centroid-shift Technique F.G. Kondev et al., Phys. Rev. C60 (1999) Supported by the Office of Nuclear Physics, US DOE

  9. To summarize … • The transition quadrupole moment (Qt) deduced from the DSAM technique is dependent on: • the model used for the stopping powers of the recoiling nuclei, which act as a clock in the DSAM technique • the model used for the side-feeding time distribution. Usually, a rotational cascade consisting of three or more transitions is used, which has a different Qt value than that for the main cascade • the validity of the rotational model at high-angular momentum • Therefore, the transition quadrupole moment (Qt) deduced using the DSAM technique should be distinguished from the directly measured (for a list of methods see 2005St24) spectroscopic (static) quadrupole moment (Q).

  10. Recommendations Recommendation 1: In ENSDF, a new symbol MOME2T is introduced to represent the transition quadrupole moment in units of barns, deduced using the DSAM technique. Recommendations 2: When MOME2T values are reported for individual levels (“line-shape” DSAM), these should be given in a continuation record that follows the corresponding level record (see Example 1). When a single MOME2T value is assigned to the whole band (“centroid-shift” DSAM), it should be given in the comment records for band ID label (see Example 2). Example 1: L 1000.0 12+ 3.2 PS 3 2 L $ MOME2T=4.7 2 (2010YYxx) L 1200.0 14+ 1.2 PS 1 2 L $ MOME2T=4.5 5 (2010YYxx) Example 2: CL BAND(A)$ BAND LABEL or BAND ID. 2CL MOME2T=4.7 2 (2010YYxx) L 1800 14+ A

  11. Recommendations – cont. Recommendation 3: It would be useful to include additional information about the model(s) or/and the assumptions used for the stopping powers and the side-feeding patterns (see Example 3) Example 3: CL BAND(A)$ BAND LABEL or BAND ID. 2CL MOME2T=4.7 2 (2010YYxx). Deduced using the centroid-shift DSAM. The stopping powers of Ziegler et al. (^TRIM computer code) were used. The side feeding was modeled as a cascade of three transitions with MOME2T(side feeding)=2.5 3. Recommendation 4:It would be useful that corresponding NSR key-numbers be assigned to references that deal with various stopping powers models, for example J.F. Ziegler, J.P. Biersack and U. Littmark, The Stopping and Range of Ions in Solids (Pergamon, New York, 1985); http://www.srim.org/ and L. C. Northcliffe and R. F. Schilling, Nuclear Data Tables, 7, 233 (1970).

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