252ES 256MD A DECAY 2000Ah02 21NDS 202103
252ES H TYP=FUL$AUT=A.M. MATTERA, S. ZHU, A.B. HAYES, E.A. MCCUTCHAN$
252ES2 H CIT=NDS 172, 543 (2021)$CUT=1-Jan-2021$
252ES c 2000Ah02: {+256}Md was produced in reactions of {+253}Es(|a,2n) at
252ES2c the Argonne 152-cm cyclotron, and was removed from the target by a
252ES3c helium jet system and chemically isolated. |a, |g and |a-|g were
252ES4c measured with Si and Ge(Li) detectors. Five |a decays were observed
252ES5c and their energies were measured with samples covering small solid
252ES6c angle to the Si detector for minimizing |a-electron summing, and with
252ES7c calibration standards from 1991Ry01. Total 4 |g rays with E|g=99.4
252ES8c keV, 122.8 keV, 378.5 keV and 408.5 keV were observed in coincidence
252ES9c with the 7206-keV |a. One |g ray with E|g=445 keV {I1} was in
252ESac coincidence with the 7142-keV |a. These |g rays were not placed in
252ESbc the level scheme of {+252}Es because of the complexity of levels in
252EScc an odd-odd nucleus.
252ES c Other: 2019Ah04, 1993Mo18, 1971Ho16, 1970Ri12.
252ES c The 5 |a branches are adopted from 2000Ah02 based on the following
252ES2c considerations. The peak shape of high energy and weak |a rays in the
252ES3c spectrum is clearly visible. No peaks with intensity larger than 1%
252ES4c are visible. In 1993Mo18, the determination of the high energy |a
252ES5c rays was not a unique solution because of poor detector resolution
252ES6c and conversion-electron summing incurred by the large detector solid
252ES7c angle (|?30% of 4|p). In 1971Ho16, the peaks in the region beyond 7.3
252ES8c MeV are statistically less certain. In 1970Fi12, the statistics in
252ES9c the high energy region are also poor to make a definite assignment of
252ESac every peak.
252ES cG $Es K x-rays measured by 2000Ah02: K|a{-1}| = 118.0 keV, K|a{-2}| =
252ES2cG 112.5 keV, K|b{-1}'| = 132.5 keV, K|b{-2}'| = 137.0 keV
252ES cA E,IA$From 2000Ah02 unless otherwise noted. Other measurements:
252ES2cA 1993Mo18, 1971Ho16 and 1970Fi12. 1993Mo18 with E|a calibration
252ES3cA standards of 1973Ry07: 7155 {I5} (21% {I2}); 7221 {I3} (47% {I3});
252ES4cA 7455 {I6} (4.5% {I5}); 7532 {I10} (2.5% {I5}); 7611 {I10} (1.5%
252ES5cA {I5}); 7678 {I6} (4.0% {I4}); 7773 {I16} (0.5% {I3}), and an
252ES6cA unresolved group of |a between 7221 and 7455 (19% {I2}). 1971Ho16
252ES7cA with E|a({+253}Es)=6.640 MeV and E|a({+256}Fm)=6.925 MeV as
252ES8cA calibration energies: 7.160 MeV {I15} (16% {I2}); 7.23 MeV {I1} (63%
252ES9cA {I4}); 7.33 MeV {I3} (4% {I1}); 7.46 MeV {I3} (5% {I1}); 7.49 MeV
252ESacA {I2} (6% {I1}); 7.67 MeV {I3} (2% {I1}) and 7.72 MeV {I2} (4% {I1}).
252ESbcA 1970Fi12 with E|a({+253}Es)=6.632 MeV and E|a({+256}Fm)=6.911 MeV as
252ESccA calibration energies: 7.136 MeV {I5} (21% {3}); 7.202 MeV {I5} (69%
252ESdcA {I5}); 7.44 MeV {I1} (|?2%); 7.58 MeV {I1} (|?2%); 7.64 MeV {I1}
252ESecA (|?4%) and 7.67 MeV {I1} (|?2%).
252ES cA HF$r{-0}({+252}Es)=1.488 {I7}, unweighted average of
252ES2cA r{-0}({+250}Cf)=1.4887 {I8}, r{-0}({+252}Cf)=1.499 {I4} and
252ES3cA r{-0}({+252}Fm)=1.4762 {I19}.
252ES cL E$Calculated from E|a's by assuming that the 7676-keV |a feeds the
252ES2cL {+252}Es g.s based on the fact that it is not in coincidence with any
252ES3cL of the observed |g rays and having the highest energy of all of the
252ES4cL observed |a transitions.
252ES cL J$From the Adopted Levels. Support derived from this dataset is given
252ES2cL in the comments.
252ES cG E$Assigned to {+252}Es based on them in coincidence with 7207|a,
252ES2cG except 445|g which is in coincidence with 7142|a (2000Ah02).
256MD P 0.0 (1-) 77.5 M 16 7737 SY
256MD cP T$weighted average of 78.1 min {I18} (1993Mo18), 77 min {I5}
256MD2cP (1971Ho16), and 75 min {I4} (1970Fi12).
256MD cP QP$From 2017Wa10. Deduced Q(|a)=7798 {I8} assuming the 7676-keV
256MD2cP |a decays to the {+252}Es g.s.
252ES N 0.095 5
252ES cN BR$weighted average of 8.5% {I8} (1970Fi12), 9.9% {I5} (1971Ho16) and
252ES2cN 11% {I3} (1993Mo18).
252ES G 99.4
252ES G 122.8
252ES G 378.5
252ES G 408.5
252ES G 445 1
252ES L 0.0 (5-)
252ES A 7676 8 2.5 5 4.31E3 91
252ES L 35 11
252ES A 7642 8 2.1 5 3.8E3 10
252ES L 436 9
252ES A 7247 5 2.5 5 96 21
252ES L 476 8 (1-)
252ES cL J$Favored |a from {+256}Md g.s, which was suggested to be J=1-, K=0
252ES2cL with configuration |p7/2{+-}[514]~#|n7/2{++}[613] (1993Mo18).
252ES A 7207 2 71 2 2.33 16
252ES cA E$From 2019Ah04.
252ES L 542 9
252ES A 7142 5 22 1 4.1 4