81BR 81KR EC DECAY (2.13E5 Y) 1988AX01 25NDS 202501
81BR H TYP=FUL$AUT=M. Shamsuzzoha Basunia$CIT=NDS 199, 271 (2025)$
81BR2 H CUT=1-Sep-2024$
81BR c Others: 1974Ch40, 1972ScYQ, 2010Mi21, 2017Ra27, 2018Ga29.
81BR c 1988Ax01: {+81}Kr from {+81}Rb (4.576 h) decay; Ge, NaI
81BR2c and proportional counters;
81BR3c measured I(276|g), I(Br x rays), |g-x ray coin, M/L capture ratio.
81BR c 1972ScYQ, 1974Ch11: {+81}Kr from {+80}Kr(n,|g), enriched target.
81BR2c Measured with Ge(Li) and Si(Li) (1972ScYQ), or proportional counter
81BRxc (1974Ch40).
81BR c 2017Ra27, 2018Ga29: Detection of triple coincidences of two
81BR2c fluorescence photons and low-energy 'shaked' electrons (cascades of
81BR3c Auger electrons or Auger electrons + an ejected K-electron) emitted
81BR4c when double K-shell vacancy is caused in rare decay processes in
81BR5c {+81}Se decay. Measurements were carried out for several years
81BR6c at the deep-underground low-background laboratory of the Baksan
81BR7c Neutrino Observatory (BNO), Institute for Nuclear Research of the
81BR8c Russian Academy of Sciences, Neutrino, at a depth of 4900 m w.e. (water
81BR9c equivalent) depth. A large low-background proportional counter (LPC),
81BRac filled with the krypton sample was used to detect triple coincidences
81BRbc of 'shaked' electrons and two fluorescence photons. In the study of
81BRcc {+81}Kr |e decay, cosmogenic radioisotope {+81}Kr with a volume
81BRdc activity of 0.076 {I4}/minute/liter Kr was contained in the
81BRfc original atmospheric krypton. The source activity was |?4 |e
81BRgc decays/min. Data were collected for 1167 days of live measurement.
81BRhc Deduced probability of K-shell vacancies per K-electron capture,
81BRic produced as a result of the shake-off process.
81BR cG E From 1972ScYQ
81BR cG M,MR From Adopted Gammas
81BR cL E From E|g.
81BR cL J,T From Adopted Levels.
81BR dG CC$From BrIcc v2.3e (17-Jun-2020) 2008Ki07, "Frozen Orbitals" appr.
81BR N 0.00299 20 1.0 1.0
81BR cN NR 0.00299 {I20} from measured |e branching to 276 level=0.30%
81BR2cN {I2} (1988Ax01) and adopted |a(276|g). This conflicts with I|g
81BR3cN normalization=0.036 {I4} implied by measured I(276|g)/I(K x-ray,
81BR4cN Br)=0.068 {I8} (1972ScYQ), assuming fluorescence yield (Br)=0.618
81BR5cN {I19}, K-capture to total-capture ratio=0.847, |a=0.0112.
81BR PN 3
81KR P 0 7/2+ 2.13E5 Y +16-26 280.9 5
81KR cP J,T from {+81}Se Adopted Levels
81KR cP QP$from 2021Wa16
81BR L 0 3/2-
81BR cL $In 2010Mi21, total intensity of K component of the radiative electron
81BR2cL capture (REC) was measured to be 1.2|*10{+-4} {I1} and
81BR2cL 1.64|*10{+-4} {I8} from two measurements, with an average value of
81BR3cL 1.42|*10{+-4} {I22} per K capture.
81BR E 99.70 210.98 5 99.70 2 1U
81BRS E CK=0.84731 9$CL=0.12712 8$CM+=0.02557 2
81BR cE IE 100% minus branch to 276 level (0.30% {I2}).
81BR cE E measured |eL(exp)/|eK(exp)=0.146 {I5} (1974Ch40); this
81BR2cE corresponds to the theoretical ratio for Q(|e)=305 {I+35-29}.
81BR cE $2017Ra27, 2018Ga29 report measurement of probability of K-shell
81BR2cE vacancies per K-electron capture
81BR3cE P{-KK}=5.7|*10{+-5} {I8}(stat) {I4}(syst) (2017Ra27,2018Ga29), deduced
81BR4cE from a total of 42 {I7}(stat) {I3}(syst) triple-coincidence events
81BR5cE related to double-K-shell-vacancy production
81BR L 275.991 115/2- 9.7 PS 14
81BR E 0.30 2 9.35 15 0.30 2
81BRS E CL=0.69 3$CM+=0.31 3
81BR cE E from measured |e{-M}/|e{-L}=0.42 {I5}, 1988Ax01 deduce E=4.7
81BR2cE {I5} assuming capture ratios from allowed decay theory are applicable
81BR3cE to this highly hindered first forbidden nonunique transition.
81BR cE IE from measured I(276|g)/I(Br K| x ray)=0.30 {I2} (1988Ax01).
81BR G 275.990 11100 M1+E2 -0.10 3 0.0081614
81BRS G KC=0.00724 13$LC=0.000781 14$MC=0.0001242 23
81BRS G NC=1.158E-5 21