254FM 254ES B- DECAY (39.3 H) 1973AH04,1962UN01,1971PO2019NDS 201902
254FM H TYP=FUL$AUT=BALRAJ SINGH$CIT=NDS 156, 1 (2019)$CUT=31-Jan-2019$
254FM c 1973Ah04: mass-separated sources of {+254m}Es, measured E|a, I|a, E|g,
254FM2c I|g, x-ray energies and intensities, |a|g-, |a(ce)-, and
254FM3c |a(L x ray)-coin using Argonne magnetic |a-spectrometer and Au-Si
254FM4c surface-barrier detectors for |a detection, and Ge(Li) detectors for |g
254FM5c and x rays. This paper is mainly about the level scheme for {+250}Bk
254FM6c from |a decay of 39.3-hour {+254}Es.
254FM c 1962Un01: measured E|b{+-}, ce, E|g, I|g, x rays, (|b{+-})|g-coin,
254FM2c |g|g-coin using double-lens beta-ray spectrometer for |b{+-} and
254FM3c conversion electrons and NaI(Tl) detector for |g rays
254FM c 1971Po20: precise atomic-electron binding energies in fermium were
254FM2c deduced from precise measured energies of 40-, 45-, and 104-keV
254FM3c transitions in ce data.
254FM3c Also 1975FrZZ (priv. comm. from one of the authors of 1971Po20)
254FM4c provided additional details of internal conversion data. This
254FM5c communication mentioned a forthcoming paper on the decay of 39.3-h
254FM6c decay of {+254}Es, but no paper seems to have appeared according to
254FM7c the search of the NSR database
254FM c 1963Ho07: measurement of transition energies from ce data
254FM cB IB(X)$Note that the quoted feeding does not include transition
254FM2cB intensity of the 39.8-keV transition. This transition is
254FM3cB expected to be weak as mentioned in priv. comm. 1975FrZZ
254FM tG $----------------------------------------------------------------
254FM tG Energies and intensities of Fm x-ray) (1973Ah04)
254FM tG E(x-ray) I(x-ray) Fm x-ray
254FM tG ---------- ------------ ----------------------
254FM tG 115.280 {I15} 0.51 {I5} K|a{-2}
254FM tG 121.065 {I15} 0.77 {I7} K|a{-1}
254FM tG 135.18 {I4} K|b{-3}
254FM tG 0.33 {I4} K|b{-3}+K|b{-1}
254FM tG 136.55 {I4} K|b{-1}
254FM tG 140.49 {I4} K|b{-2}+K|b{-4}
254FM tG 0.110 {I15} K|b{-2}+K|b{-4}+O
254FM tG 141.72 {I5}
254FM tG
254FM tG $I(x-ray) values are per 100 decays of 39-h {+254}Es
254FM tG $Other measurements:
254FM tG $I(L x-rays):I(K x-rays):I(649|g)=90 {I15}:6 {I1}:100 (1962Un01).
254FM2tG Note that the measured L/K and L/(I(649|g) disagree with those
254FM3tG expected from the decay scheme
254FM tG $----------------------------------------------------------------
254FM cG $A |g with E|g=989 {I7}, I|g=0.7 and Ice(K)=0.011 {I4} was reported
254FM2cG by 1962Un01, but no such |g reported by 1973Ah04
254FM cG $The measured total intensity of I(K| x ray)=1.72 {I10} (1973Ah04) is
254FM2cG in good agreement with the total I(K| x ray)=1.63 {I7}, deduced by
254FM3cG evaluator from I|g and |a(K) data
254FM cG E$Measurements by 1973Ah04. Others: 1962Un01, 1963Ho07
254FM cG RI$Per 100 |b{+-} decays, obtained by 1973Ah04 from |a-count
254FM2cG rate of {+254}Fm which was in equilibrium with 39-h {+254}Es.
254FM cG M$Multipolarities are from ce data of 1962Un01. The electron
254FM2cG intensities from 1962Un01 listed here are per 100 |b decays (these
254FM3cG were measured relative to the total |b spectrum). Other
254FM4cG measurement: 1963Ho07.
254FM cL E$From least-squares fit to E|g data
254FM cL J,T$From Adopted Levels
254FM CL BAND(A)$Ground-state band
254FM CL BAND(B)$K|p=2+ |g-vibrational band
254ES P 84.2 25 2+ 39.3 H 2 1088 3
254ES cP J,T$From {+254}Es Adopted Levels
254ES cP QP$From 2017Wa10
254FM N 1.02 1.02 0.98 2 1.02
254FM cN NR$The |g intensities are per 100 decays of {+254}Es
254FM cN BR$%|b{+-}=98 {I2}
254FM PN 1.0 1.0 3
254FM L 0.0 0+ 3.240 H 2 A
254FM L 44.992 10 2+ A
254FM B 1127 2 25.0 36 8.5 1
254FMS B EAV=361.1 15
254FM cB E$measured by 1962Un01 (Kurie plot). The shape of the |b
254FM2cB spectrum showed that any contribution from a L=2 component was
254FM3cB insignificant. Contribution from second-forbidden |b branch to the 0+
254FM4cB g.s. is assumed negligible.
254FM cB IB$deduced by evaluator from 98 {I2}-(transition intensity of 693|g)-
254FM2cB (summed transition intensity of |g rays feeding the 45 level), assuming
254FM3cB no |b feeding to the g.s. that involves 2+ to 0+ |b transition
254FM G 44.992 10 0.062 4 E2 1172 72.3 43
254FMS G LC=841 12$MC=242 4
254FMS G NC=68.8 10$OC=17.33 25$PC=2.71 4$QC=0.00630 9
254FM cG E$weighted average of 45.000 {I15} (1973Ah04) and 44.988 {I10}
254FM2cG (1971Po20, deduced from precise ce data for 693.7 and 648.7 gamma rays)
254FM CG M$ELC>200 (1962Un01)
254FM cG TI$deduced by evaluator from summed transition intensity of |g rays
254FM2cG feeding the 45 level + I(|b) to 45 level
254FM cG RI$deduced by evaluator from I|g+ce(45|g) and total conversion
254FM2cG coefficient for 45|g. Other: measured value of 0.049 {I5} in 1973Ah04
254FM3cG seems to have been underestimated, possibly due to detection efficiency
254FM4cG issues for low-energy |g rays
254FM L 149.349 16 4+ A
254FM G 104.356 12 0.180 17 E2 21.7
254FMS G LC=15.60 22$MC=4.49 7
254FMS G NC=1.277 18$OC=0.323 5$PC=0.0515 8$QC=0.000203 3
254FM cG RI$other: 0.20 {I2} (1975FrZZ)
254FM cG E$weighted average of 104.350 {I15} (1973Ah04) and 104.360 {I12}
254FM2cG (1971Po20, deduced from precise ce data for 648.7 and 544.3 |g rays,
254FM3cG and 688.5 and 584.2 |g rays)
254FM CG M$ECC=20 {I5} (1962Un01); L1/L2=0.066 {I2} (1975FrZZ,1971Po20)
254FM cG $Ice(L):Ice(M+N+O)=3.0 {I4}:1.0 {I2} (1962Un01).
254FM L 693.66 4 2+ B
254FM B 56 4 6.9 1 X
254FMS B EAV=137.7 13
254FM cB IB$
254FM cB E$475 {I5} measured by 1962Un01 (Kurie plot), which may contain
254FM2cB contribution from |b transition with E|b(end-point)=440 feeding the
254FM3cB 734 level
254FM cB $From |b spectra, measured I|b(475|b)/I|b(1127|b)=3.0 {I5} (1962Un01)
254FM G 544.28 10 0.90 8 E2 0.0612
254FM cG RI$other: 0.98 {I7} (1975FrZZ)
254FMS G KC=0.0335 5$LC=0.0202 3$MC=0.00547 8
254FMS G NC=0.001542 22$OC=0.000397 6$PC=7.02E-5 10$QC=1.776E-6 25
254FM CG M$EKC=0.00256 {I40} (1975FrZZ), 0.03 {I1} (1962Un01)
254FM cG $Ice(K)=0.027 {I8} (1962Un01).
254FM G 648.69 7 29 2 E2(+M1) 9 GT 0.0427 13
254FMS G KC=0.0262 10$LC=0.0121 2$MC=0.00321 4
254FMS G NC=0.00090 2$OC=0.000234 3$PC=4.20E-5 7 $QC=1.27E-6 4
254FM cG E$648.12 {I40} (1963Ho07) from ce data
254FM cG RI$other: 31.6 {I22} (1975FrZZ)
254FM CG M,MR$from EKC=0.0255 {I7}, K/L1=4.91 {I15}, L1/L2=0.97 {I3},
254FM2CG L1/L3=5.32 {I25} (1975FrZZ). Others: EKC=0.023 {I3} (1962Un01). Using
254FM3CG ce intensities from 1962Un01 and I|g from 1973Ah04, evaluator obtains
254FM4CG EKC=0.0269 {I20}, ELC=0.0128 {I14} and EMC+=0.0045 {I15}
254FM CG MR$deduced by the evaluator from ce data in 1975FrZZ
254FM cG $Ice(K):Ice(L):Ice(M+N+O)=0.78 {I2}:0.37 {I3}:0.13 {I4} (1962Un01).
254FM G 693.67 7 24.8 17 E2 0.0359
254FMS G KC=0.0225 4$LC=0.00981 14$MC=0.00260 4
254FMS G NC=0.000731 11$OC=0.000189 3$PC=3.41E-5 5$QC=1.074E-6 15
254FM cG E$693.05 {I40} (1963Ho07) from ce data
254FM cG RI$other: 27.0 {I19} (1975FrZZ)
254FM CG M$from K/L1=4.90 {I15}, L1/L2=1.03 {I3}, L1/L3=6.06 {I25} (1975FrZZ).
254FM2CG Other: EKC=0.021 {I3} (1962Un01)
254FM cG $Ice(K):Ice(L):Ice(M+N+O)=0.83 {I3}:0.38 {I4}:0.15 {I4} (1962Un01)
254FM2cG for 694+689 doublet
254FM cG $Evaluator deduces Ice(K)=0.56 {I4} and Ice(L)=0.243 {I17} for 693.67|g
254FM2cG using its I|g value from 1973Ah04, |a(K)(theory)=0.0225 {I4}, and
254FM3cG |a(L)(theory)=0.00981 {I14} from BrIcc; the remaining Ice(K)=0.27 {I5}
254FM4cG Ice(L)=0.14 {I4} is assigned to the 688.5|g from 734 level
254FM L 733.54 4 3+ B
254FM B 16 4 7.3 1 X
254FMS B EAV=125.1 13
254FM G 39.881 10 (E2) 2.10E3
254FMS G LC=1507 22$MC=434 6$NC=123 2$OC=31.1 5$PC=4.84 7$QC=0.01054 15
254FM cG E$deduced from precise ce data for 688.5 and 648.7 |g rays, and
254FM2cG 584.2 and 544.3 |g rays (1971Po20)
254FM cG M,MR$E2(+M1) with |d>1.75 suggested by 1975FrZZ from measured L2/L3
254FM2cG and M2/M3 values, but the numerical values of these subshell ratios
254FM3cG were not listed in the communication. Also in an e-mail communication
254FM4cG of April 4, 2017, I. Ahmad (ANL), first author of 1973Ah04 and a
254FM5cG collaborator of author of 1975FrZZ, suggested that |d(E2/M1) cannot
254FM6cG be deduced since values for M1 multipolarity are very small.
254FM7cG Evaluator assigns this transition mainly as E2 based on estimate by
254FM8cG 1975FrZZ
254FM cG $Conversion electron intensity of the 39.8-keV transition is not
254FM2cG available but expected to be weak as mentioned in 1975FrZZ priv. comm.
254FM G 584.18 10 2.9 2 E2(+M1) 9 GT 0.0538 17
254FMS G KC=0.038 9$LC=0.0177 15$MC=0.0047 4
254FMS G NC=0.00133 10$OC=0.00034 3$PC=6.2E-5 6$QC=1.9E-6 4
254FM cG E$583.26 {I40} (1963Ho07) from ce data
254FM cG RI$other: 3.2 {I2} (1975FrZZ)
254FM CG M,MR$from EKC=0.0296 {I15}, K/L1=4.43 {I22}, L1/L2=0.86 {I5}
254FM2CG (1975FrZZ). Others: EKC=0.042 {I5} (1962Un01), using ce intensity from
254FM2CG 1962Un01 and I|g from 1973Ah04, evaluator also obtains EKC=0.042 {I5}
254FM cG $Ice(K)=0.123 {I13} (1962Un01).
254FM G 688.52 7 12.5 9 E2(+M1) 8 GT 0.0378 13
254FMS G KC=0.0239 11$LC=0.0102 2$MC=0.00270 5
254FMS G NC=0.000760 12$OC=0.000196 4$PC=3.55E-5 7 $QC=1.13E-6 6
254FM cG E$688.20 {I40} (1963Ho07) from ce data
254FM cG RI$other: 13.6 {I10} (1975FrZZ)
254FM cG $Ice(K)=0.27 {I5}, Ice(L)=0.14 {I4} deduced by the evaluator, see
254FM2cG comment for 693.67|g
254FM CG M,MR$from EKC=0.0240 {I7}, K/L1=5.17 {I15}, L1/L2=1.03 {I3}
254FM2CG (1975FrZZ). Other: EKC=0.022 {I4}, ELC=0.011 {I3} and K/L=1.9 {I6}
254FM3CG (deduced by evaluator from ce data given above)