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 18 F: 1041γ g.s. transition (not in Endt’s 1974 papers); 8.6(2) for 6 Li: 3560γ g.s transition; 4.3(5) for 40 Ca. 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 18 F.

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

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

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

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 56 Fe. However, this value is erroneous. The branching ratios of the two gamma rays from 3756, 6+ level got reversed! (Strange Endt error!! Even Homer and Vyāsa took a nap now and then …… ). The value should be 0.6. The next highest value in Endt’s paper was 1.6(5) for 940γ from 1330 level in 50 V. 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 54 Mn.

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 140 La. 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. NUCLIDEElevelEgammaBM1WJπJπ 91MO 5243.3 284.52.4 (31/2-) 109IN 3410.3 207.95.2(19) (23/2-) 113SN 2039.99 172.45(3) 7/2+ 113CD 680.526 382.04.4(12) (3/2+) 113CD 680.526 364.35.0(13) (3/2+) 136ND 9492 544.03.3(17) (24+) 136ND 8947.7 481.03.2(15) (23+) 142EU 2751.33+X 140.62.2(5) 15- 142CE 2540.2 358.76(3) 4+ 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 199 Pb. ● Most of these are in the region 193-199 Pb; and for magnetic-dipole rotational bands.

17. Highest BM1W values A>150 NUCLIDEElevelEgammaBM1WJπJπ 194PB 6396.1 375.52.4(4)(22-) 194PB 6020.5 336.23.0(3)(21-) 194PB 5684.4 260.14.8(+13-9)(20-) 197PB 6712.3 446.12.4(12)51/2+ 198PB 9176.1 463.62.0(6)(29+) 198PB 8712.5 421.72.3(7)(28+) 198PB 8290.8 374.43.4(10)(27+) 198PB 6483.9 342.23(3)21- 198PB 6141.6 278.42.8(12)20- 198PB 5863.2 215.02.1(3)19- 198PB 5648.2 155.73.5(6)18- 199PB 1571.2+Y 377.13.2(16)(49/2+) 199PB 1194.2+Y 323.14(3)(47/2+) 199PB 7895.1+X 411.32.2(9)(53/2-) 199PB 7483.7+X 363.12.5(9)(51/2-) 199PB 7120.5+X 316.35.4(20)(49/2-) 199PB 6804.2+X 273.85.8(21)(47/2-) 199PB 6530.4+X 240.14(+4-3)(45/2-) 199PB 6290.3+X 234.64(+4-3)(43/2-) 208TL 39.858 39.92.1(3)4(+)

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. NUCLEUSLEVELGAMMABM1W 32 S12049392226.46 51 V11587 37.82 21 Na3544.33544.0 15.39 23 Na 10519 2627.710 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 values from energy levels above the proton (or neutron) separation energy, when the full width Γ (or total T 1/2 ) 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 Mass Region Endt RUL ENSDF RUL Number of values above RUL Highest value Possible new RUL 6-2010 110.9(21)12? 21-4451004.3(5)5? 45-903302.30(6)3 91-1501326,75.2(19)7? >1502205.8(21)8?

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 Laboratory Presented 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) Thomas W. Burrows NSDD 2007, St. Petersburg June 11-15, 2007

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.,  p or  n ) given on Level continuation record, derive   from  and  i –Else if %IT or %G given on Level continuation record, use for calculation (%IT is currently checked for) Thomas W. Burrows NSDD 2007, St. Petersburg June 11-15, 2007

29. RULER Upgrades (cont.) –If none of the above are given and T 1/2 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  -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  -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. Thomas W. Burrows NSDD 2007, St. Petersburg June 11-15, 2007 Preferred

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  T 1/2 and  %  ). Thomas W. Burrows NSDD 2007, St. Petersburg June 11-15, 2007