40AR 40K EC DECAY (1.248E+9 Y) 1999BEZQ,1999BEZS 17NDS 201702
40AR H TYP=FUL$AUT=JUN CHEN$CIT=NDS 140, 1 (2017)$CUT=30-Sep-2015$
40AR D THE EVALUATION OF R. G. HELMER (1999BEZQ,1999BEZS) IS UPDATED
40AR2D by the evaluator
40AR C 1999BEZQ, 1999BEZS: EVALUATIONS OF 40K DECAY
40AR C MEASUREMENTS: 2014Be25, 2013Be06, 2004Ko09, 2002GR01, 2001NO10,
40AR2C 1977CE04, 1972GO21, 1967Mc10, 1966FE09, 1965LE15, 1965BR25, 1962FL05,
40AR3C 1962EN01, 1961GL07, 1960Sa31, 1960EG01, 1959KE26, 1957WE43, 1956MC20,
40AR4C 1955BA25, 1955KO21, 1955Su38, 1953BU58, 1952FE16, 1951GO29, 1951DE34,
40AR5C 1950SA52, 1949Ov01,1948EV09, 1947GL07. This list is not complete, see
40AR6C 1978LeZA for several other references that are not present in ^NSR
40AR7C database.
40AR c The decay scheme, which includes the |b{+-} decay to the
40AR2c ground state of {+40}Ca and two levels in {+40}Ar, is complete since
40AR3c these are the only levels in the daughter nuclides below the
40AR4c respective decay energies.
40AR c In principle, the 1460-keV |g ray could be used for energy
40AR2c calibration. However, in a Ge semiconductor detector the
40AR3c apparent |g-ray energy depends on the source-detector
40AR4c configuration and {+40}K sources usually consist of a large volume
40AR5c of material, so this E|g is usually not useful. This also means
40AR6c that in most cases the uncertainty in the observed energy is
40AR7c much larger than that given here.
40AR d Decay data evaluated by R. G. Helmer, September 1996 with
40AR2d minor editing in July 1998. This
40AR3d evaluation was done under the collaboration including evaluator
40AR4d from Laboratoire Primaire des Rayonnments Ionisants (LPRI) in
40AR5d France; Physikalisch-Technische Bundesanstalt (PTB) in Germany;
40AR6d Imperial College in the United Kingdom; and Brookhaven National
40AR7d Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL),
40AR8d and Idaho National Engineering and Environmental Laboratory
40AR9d (INEEL) in the United
40AR0d States. This evaluation was reviewed and accepted by
40ARAd evaluator in this collaboration.
40K P 0 4- 1.248E+9 Y 3 1504.40 6
40K cP J$From unique 3rd forbidden |b{+-} spectral shape for decay
40K 2cP to 0+ level and L transfer in charge-particle reactions.
40K CP T$From 2004Ko09 and 2002Gr01; the same value from measurements of
40K 2CP specific activity of natural potassium salts using liquid-scintillation
40K 3CP counting (^LSC) technique. (2002Gr01 reported a value of 1.248E+9 Y 2,
40K 4CP later adjusted to 1.248E+9 Y 3 by 2004Ko09 to correct the quoted
40K 5CP uncertainty on measured isotopic abundance of 40K). Both papers used
40K 6CP natural abundance of 40K as 0.01167% 2 (1975Ga24). The natural
40K 7CP abundance of 40K=0.0117% 1 (as recommended in the International Union
40K 8CP of Pure and Applied Chemistry 70, 217 (1998), based on the measured
40K 9CP value of 1975Ga24) would give about four times larger uncertainty on
40K ACP T1/2. The earlier values of 1.265E+9 Y 13 (1999BeZS,1999BeZQ)
40K BcP based on recomputation of 1.277|*10{+9} y {I8} (evaluation by
40K CCP 1973EnVA); and 1.26E+9 Y 1 (evaluation by 1990Ho28 from 14 different
40K DCP measurements out of a total of 34 measurements listed) are in good
40K ECP agreement. VARIATION OF T1/2 DUE TO ENVIRONMENTAL CONDITIONS HAS BEEN
40K FCP STUDIED BY 2001NO10, WHERE NO SIGNIFICANT EFFECT HAS BEEN REPORTED.
40K GCP Earlier (pre-1977) measurements of partial (B- and CE) and/or total
40K HCP T1/2 of 40K:
40K ICP 1977Ce04, 1972Go21, 1966Fe09, 1965Le15, 1965Br25, 1962Fl05, 1961Gl07,
40K JCP 1960Sa31, 1960Eg01, 1959Ke26, 1957We43, 1956Mc20, 1955Ba25, 1955Ko21,
40K KCP 1955Su38, 1953Bu58, 1950Sa52, 1947Gl07. Another 16 references (from
40K LCP 1931 to 1971) are listed by 1990Ho28 and in the 1978 ^Table of
40K MCP ^Isotopes (1978LeZA); but are not present in the ^NSR database.
40K dP T$1.277|*10{+9} y {I8} from evaluation of 1973EnVA, where the |b{++}
40K 2dP branch to the {+40}Ar ground state, whose intensity has been measured,
40K 3dP was taken into account, but it appears that the corresponding |e decay
40K 4dP was neglected. The |e/|b{++} ratio for this 3U transition has been
40K 5dP estimated as follows. For a 1U transition, the theoretical value
40K 6dP for this ratio is 8.5 and for a 2U transition it is 45.2. If
40K 7dP the 3U ratio is larger by the same factor, 45.2/8.5, than the
40K 8dP |e/|b{++} ratio is |?240. In the calculation of t{-1/2}, a value of
40K 9dP 200 {I100} was used. The revised |b{+-}, |b{++}, and |e branchings are
40K AdP given in the corresponding tables and are based on the |g/|b{+-} and
40K BdP |b{++}/|b{+-} data in 1973EnVA. There are 1.5405|*10{+22} atoms of
40K CdP {+40}K per gram of natural K based on an average atomic mass of 39.095
40K DdP and an atomic abundance of 1.178|*10{+-4} {I4} (1973EnVA). From the
40K EdP measured |b{+-} activity of 27.89 {I15} per second for 1 g of natural
40K FdP K and I(|b{+-})=89.14% {I11}, the total activity is 31.29 {I17} per s
40K GdP and T{-1/2}=4.0207|*10{+16} s or 1.274|*10{+9} y {I8}. With a later
40K HdP value of {+40}K/K=1.17|*10{+-4} {I1} (1990Ho28),
40K IcP T{-1/2}=3.992|*10{+16} s {I40} or 1.265|*10{+9} y {I13}.
40K cP QP$From 2012Wa38
40AR N 9.33 0.1072 11 9.33
40AR PN 1.0 1.0 3
40AR cN NR$I|g(1460 |g) is from the measured |g/|b{+-}
40AR2cN ratio (evaluated in 1973EnVA), which can be obtained from
40AR3cN I(|e,1460)/(1+|a+IPFC). |a(1460)=2.5|*10{+-5} and
40AR4cN IPFC=7.3|*10{+-5} {I5}, so the correction for these is 0.01% and is
40AR5cN completely negligible compared to the 1% uncertainty in
40AR6cN I(|e,1460).
40AR cN BR$deduced by the present evaluator based on
40AR2cN I|g(1460|g)/I|b{+-}=0.1195 {I14}, which is equal to
40AR3cN I(|e to 1461 level)/I|b{+-}, and I(|b{++})/I(|b{+-})=1.12|*10{+-5}
40AR4cN {I14} from evaluation of 1973EnVA, and
40AR5cN |e/|b{++}({+40}K to {+40}Ar g.s.)=45.2 {I14} (3U theory), with
40AR6cN all |b{++} decay proceeding to {+40}Ar ground state. Previously
40AR7cN evaluated value by 1999BeZQ,1999BeZS is 0.1086 {I13} based on the
40AR8cN estimation of |e/|b{++}=200 {I100} for the unique 3rd forbidden branch
40AR9cN to the {+40}Ar ground state.
40AR L 0 0+ STABLE
40AR E 0.00100 13 0.045 6 21.4 0.046 6 3U
40ARS E EAV=197.325 25$CK=0.5059 1$CL=0.04906 1$CM+=0.007191 2
40AR cE IE$from I|b{++}(to {+40}Ar g.s.)/I|b{+-}=1.12|*10{+-5} {I14} in
40AR2cE evaluation of 1973EnVA and adopted %I|b{+-}=89.28 {I11}, with
40AR3cE |e/|b{++}({+40}K to {+40}Ar g.s.)=45.2 {I14} (3U theory)
40AR cE LOGFT$from private communication from R. B. Firestone; see also
40AR2cE 1970Wa11.
40AR DE LOGFT$the LOGFT code gives LOGF0T=19.4 1, but it redivides the
40AR2DE intensity to give I(B+)=0.020 and I(EC)=0.026.
40AR L 1460.851 6 2+
40AR cL J$from Adopted Levels
40AR E 10.67 11 11.53 1 10.67 11 1U
40ARS E CK=0.7609 4$CL=0.2114 3$CM+=0.02771 4
40AR G 1460.820 5 10.66 13 E2 2.95E-5 9
40AR cG E$the evaluator has re-scaled the original values in 1979He13 using
40AR2cG the new calibration standards in 2000He14.
40AR3cG Others: 1460.75 {I6} (1967Ki10), 1460.95 {I7} (1970Ja15).
40AR cG RI$I|g(1460)=I(|e,1460)/(1+|a+IPFC)=10.67 {I11}/1.000102 {I5}.
40AR DG CC$|a(K)=2.65|*10{+-5} {I8} and
40AR2DG |a(L)=2.22|*10{+-6} {I7} interpolated from tables of 1976Ba63 and
40AR3DG |a=|a(K)+1.33*LC.
40AR4DG Internal-pair-formation coefficient is IPFC=7.3|*10{+-5}
40AR5DG {I5}, interpolated from tables of 1979Sc31.