January 2013

Contribution to A1:Contribution to A1: “ “E” means “Evaluated” in E” means “Evaluated” in

ENSDFENSDF

Alan Nichols

University of Surrey, UK

&

Manipal University, India

January 2013

Handling a half-life

Publication

Half-life (min) Publication Half-life (min)

1938 38.3 ± 0.5 1961 37.6 ± 0.3

1939 38 1965 39.0 ± 0.1

1939 38.5 ± 0.8 1968 38.4 ± 0.1

1947 38.3 ± 0.5 1969 37.9 ± 0.2

1948 38.3 1969 38.5 ± 0.1

1959 38.1 ± 0.3 1974 38.0 ± 0.1

1960 36 ± 2 1982 38.47 ± 0.05

1961 39.9 ± 0.8 2000 38.1 ± 0.8

1961 38.4 ± 0.2 (17 data sets)

January 2013

Handling a half-life

ENSDF

2001/2008: recommended a half-life value of (38.47 ± 0.05) minadoption of measured value from 1982

1991: recommended a half-life value of (38.47 ± 0.05) minadoption of measured value from 1982

1979: recommended a half-life value of (38.1 ± 0.3) minof uncertain origins; not specified

Currently adopted value represents a single subjective judgement

by the 1991 “evaluator”, while evaluators in 2001 and 2008

accepted what was done in 1991

January 2013

Handling a half-life

Publication

Half-life (min) Publication

Half-life (min)

1938 38.3 ± 0.5 1961 37.6 ± 0.3

1939 38 1965 39.0 ± 0.1

1939 38.5 ± 0.8 1968 38.4 ± 0.1

1947 38.3 ± 0.5 1969 37.9 ± 0.2

1948 38.3 1969 38.5 ± 0.1

1959 38.1 ± 0.3 1974 38.0 ± 0.1

1960 36 ± 2 1982 38.47 ± 0.05

1961 39.9 ± 0.8 2000 38.1 ± 0.8

1961 38.4 ± 0.2 (15 data sets)

ENSDF singular adoption

Limitation of relative statistical weight method 38.44 ± 0.08 minNormalised residual method 38.41 ± 0.06 min

Rajeval method 38.43 ± 0.04 min

January 2013

Handling a half-life

Publication

Half-life (min) Publication

Half-life (min)

1938 38.3 ± 0.5 1961 37.6 ± 0.3

1939 38 1965 39.0 ± 0.1

1939 38.5 ± 0.8 1968 38.4 ± 0.1

1947 38.3 ± 0.5 1969 37.9 ± 0.2

1948 38.3 1969 38.5 ± 0.1

1959 38.1 ± 0.3 1974 38.0 ± 0.1

1960 36 ± 2 1982 38.47 ± 0.05

1961 39.9 ± 0.8 2000 38.1 ± 0.8

1961 38.4 ± 0.2 (11 data sets)

Four outliers removed from final data set for analysis:Limitation of relative statistical weight method 38.37 ± 0.10 min

Normalised residual method 38.41 ± 0.04 minRajeval method 38.43 ± 0.04 min

January 2013

62 β− and 269 γ transitions – high-energy γ rays (relative Pγ):Eγ (keV) 1973 1974 1986

3601.7 0.32 ± 0.05 0.35 ± 0.05 0.53 ± 0.06

3627.1 0.13 ± 0.04 0.16 ± 0.04 0.16 ± 0.03

3636.7 0.08 ± 0.02 0.14 ± 0.03 0.22 ± 0.03

3657.5 − 0.06 ± 0.03 0.04 ± 0.02

3672.46 0.09 ± 0.02 0.16 ± 0.03 0.17 ± 0.03

3699.5 − 0.03 ± 0.03 0.07 ± 0.03

3756.1 0.18 ± 0.03 0.22 ± 0.04 −

3785.7 0.08 ± 0.03 0.14 ± 0.05 −

3793.4 0.34 ± 0.05 0.43 ± 0.06 −

↓ + 19 other γs ↓ + 15 other γs ↓ + 19 other γs −

4981.7 0.04 ± 0.02 0.07 ± 0.03 −

5227.6 − 0.02 ± 0.02 −

24 high-energy gammas omitted from ENSDF (3.75 to 5.23 MeV)

January 2013

High-energy γ transitions

24 high-energy gammas omitted from ENSDF (3.75 to 5.23 MeV)

Why?Data adopted wholesale from 1986 reference → loss of higher-energy gammas

Why?Year of publication? 1986 compared with 1973/74

Equipment? 1973, 1974 and 1986 appear to be entirely compatibleReasonably good agreement between 1973, 1974 and 1986,

while 1986 operated at a lower upper-energy cut off

High-energy nuclear levels lost entirely from proposed structure

Of some importance in decay heat calculations for irradiated fuel – 24 high-energy gammas represent 55 keV addition to total average gamma energy

(and 55 keV subtraction from total average beta energy)

January 2013

others

significant number of instances in which the crucial number in the databases assembled by ENSDF evaluators turns out to be

year of publication of measurements

– most recent data adopted simply on the basis of more recent date over which the work was undertaken, and assumption that

advances have occurred (equipment/understanding), while all earlier studies are effectively and often most unfairly rejected

January 2013

Problem of

available number of mass chain evaluators

V

maintenance of regular effort to cover needs

overall, there is a squeeze on time in order to undertake a healthy number of mass chain evaluations per annum

January 2013

“ “E” in ENSDFE” in ENSDF does not mean “Compilation” does not mean “Compilation”

oror “ “Brief Glance”Brief Glance”