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Balraj Singh and Scott Geraedts

Review of Enhanced Reduced Magnetic Dipole Transition Probabilities (BM1W>0.4) in ENSDF (March 2007 version). Balraj Singh and Scott Geraedts Department of Physics and Astronomy, McMaster University, Hamilton, Canada. IAEA-NSDD-07 meeting St. Petersburg, Russia June 11-15, 2007. Introduction.

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Balraj Singh and Scott Geraedts

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  1. Review of Enhanced Reduced Magnetic Dipole Transition Probabilities (BM1W>0.4) in ENSDF (March 2007 version) Balraj Singh and Scott Geraedts Department of Physics and Astronomy, McMaster University, Hamilton, Canada IAEA-NSDD-07 meeting St. Petersburg, Russia June 11-15, 2007

  2. Introduction • From 1974 to 1993 P.M. Endt published 6 articles on the compilation and evaluation of BELW and BMLW values in different mass regions. Values of RULs based on 5 publications (1974-1981) have been used in ENSDF for spin-parity assignments and other parameters. • In March 2007, we were approached by a physicist from Notre Dame about some recent compilation of (very) fast M1 transitions e.g. BM1W>0.4 or so. Through a code written at McMaster, complete ENSDF was scanned for BM1W>0.4 in different mass regions as classified by Endt. Nuclide, level energy, gamma-ray energy and BM1W value are tabulated for each region. • The survey is presented in this work. It reveals possible need for reassessment of the RUL values for M1 transitions.

  3. Published BM1W values for A=6-44 (by P.M. Endt) • ADNDT 13, 67 (1974): RUL=10; A=21-44 • 1974En05: NP A 235, 27: RUL=10; A=6-44 • 1979En05: ADNDT 23, 3 (1979): RUL=10; A=6-44 • 1993En03: ADNDT 55, 171: RUL=10 for A=6-20; RUL=5 for A=21-44 (not considered for ENSDF!) • Highest values: 10.8(20) for 18F: 1041γ g.s. transition (not in Endt’s 1974 papers); 8.6(2) for 6Li: 3560γ g.s transition; 4.3(5) for 40Ca. • ENSDF: RUL=10 for A=6-44 (ref: 1979En05)

  4. A=6-44 • Our search of ENSDF shows 118 values above 0.4 W.u. in this region • The highest value is 10.9(21) W.u. for Eγ=1041 keV g.s. transition from the E=1041 level in 18F.

  5. BM1W>0.4 vs. Mass number (6-20) RUL RUL

  6. BM1W>0.4 in A=6-20 mass range RUL

  7. BM1W>0.4 vs. Mass number (21-44) RUL=5 RUL

  8. BM1W>0.4 in A=21-44 mass range

  9. A=45-90 • 1979En04: Endt: ADNDT 23, 547: RUL=3 from highest value of 2.5(4) for 56Fe. However, this value is erroneous. The branching ratios of the two gamma rays from 3756, 6+ level got reversed! (StrangeEndt error!!Even Homer and Vyāsa took a nap now andthen……).The value should be 0.6. The next highest value in Endt’s paper was 1.6(5) for 940γ from 1330 level in 50V. • ENSDF: RUL=3 (ref. 1979En04, 1981En06). • Our search of ENSDF found 119 values with BM1W>0.4 W.u. • The highest value now is 2.3(6) for 54.5-keV g.s. transition in 54Mn.

  10. BM1W>0.4 vs. Mass number (45-90) RUL

  11. BM1W>0.4 in A=45-90 mass range RUL

  12. A=91-150 • 1981En06: Endt: ADNDT 26, 27: RUL=1 from value of 0.50(8) for 30-keV g.s. transition in 140La. • ENSDF: RUL=3 for A=45-150 (ref. 1979En04,1981En06) • Our scan shows there are 84 values >0.4 in ENSDF • There are seven values with BM1W>3; and 26 values >1.

  13. Highest BM1W values A=91-150

  14. BM1W>0.4 vs. Mass number 91-150 RUL

  15. Number of occurrences of BM1W values RUL

  16. A>150 • ● No published compilation of BM1W data • ● The current RUL=2 is based on scan of data in ENSDF (version ~1980) by M. Martin: first appeared in NDS 36, Sept. 1982 issue. • ● Our search found 80 BM1W values >0.4 W.u. • ● 20 of these transitions are above the RUL=2; the highest being 5.8(21), for 273.8γ from 6804.2 level in 199Pb. • ● Most of these are in the region 193-199Pb; and for magnetic-dipole rotational bands.

  17. Highest BM1W values A>150

  18. BM1W>0.4 vs. Mass number >150 RUL

  19. Number of occurrences of each BM1W value RUL

  20. 4165 transitions. Average BM1W=0.176 Most probable value=0.040

  21. Errors found in ENSDF due to use/misuse of RULER code • Some of the values in ENSDF were found to be unrealistically high. • This is due to the misuse of the RULER code • The RULER code does not take into account proton (or neutron, α-particle) decay branches when calculating BM1W valuesfrom energy levels above the proton (or neutron) separation energy, when the full width Γ (or total T1/2 ) is given in a dataset.

  22. Errors found in ENSDF due to use/misuse of RULER code (contd.) • These errors have been communicated to NNDC/Evaluators for corrections in ENSDF. • It is possible that there are other incorrect B(E,M)W values in ENSDF because proton or other particle branches may not have been considered in using RULER code. (ENSDF entries need to be checked.) • All values affecting current RUL were re-evaluated, thus the highest values for different mass regions given in this report should be reliable.

  23. Changes to the RULER program • The RULER program will be upgraded to correct for this problem as will soon be shown in a presentation from Tom Burrows (BNL).

  24. Summary

  25. Conclusions • Our current survey of BM1W values shows need to reassess RUL. • It is possible that other multipolarities also need to be reassessed based on more recent ENSDF entries. • Many current values of BELW and BMLW in ENSDF may be incorrect due to use/misuse of the RULER code.

  26. RULER Upgrades Thomas W. Burrows* National Nuclear Data Center Brookhaven National LaboratoryPresented by Balraj Singh *Email: burrows@bnl.gov Brookhaven Science Associates

  27. RULER Upgrades • RULER must be upgraded to properly handle gamma transitions from states where there is competition between gamma decay and particle emission (e.g., proton or neutron emission) NSDD 2007, St. Petersburg June 11-15, 2007 Thomas W. Burrows

  28. RULER Upgrades (cont.) • The following will be done: • If WIDTHG given on Gamma continuation record, use for calculation • Else if WIDTHG given on Level continuation record, use for calculation • Also check for and, if possible, use WIDTHG0, WIDTHG1, etc. • Else if other partial widths (e.g., Gp or Gn) given on Level continuation record, derive Gg from G and SGi • Else if %IT or %G given on Level continuation record, use for calculation (%IT is currently checked for) NSDD 2007, St. Petersburg June 11-15, 2007 Thomas W. Burrows

  29. RULER Upgrades (cont.) • If none of the above are given and T1/2 on Level record indicates a width (eV, keV, or MeV) or is very short (»10-18 sec), do one of the following: • Treat as if the g-branching is 100% and do all calculations and creation of new Gamma continuation records. Output a warning that this has been done both in the report file and the terminal output. • Treat as if the g-branching is 100% and do all calculations but do not create new Gamma continuation records. Output a warning that this has been done both in the report file and the terminal output. • Do not do any calculations and indicate that this has been done both in the report file and the terminal output. Preferred NSDD 2007, St. Petersburg June 11-15, 2007 Thomas W. Burrows

  30. RULER Upgrades (cont.) • If the evaluator has entered the data correctly, this seems to be the best procedure to avoid correlations in the uncertainties (e.g., between DT1/2 and D%g). NSDD 2007, St. Petersburg June 11-15, 2007 Thomas W. Burrows

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