Authors: Balraj Singh, Sukhjeet Singh |  Citation: ENSDF |  Cutoff date: 08-Mar-2022 

Authors: Sukhjeet Singh, Balraj Singh |  Citation: Nucl. Data Sheets 130, 127 (2015) |  Cutoff date: 15-Oct-2015 

 Full ENSDF file | Adopted Levels (PDF version) 

Q(β-)=2923 keV 11S(n)= 4705 keV 11S(p)= 5930 keV 14Q(α)= 4948 keV 18
Reference: 2021WA16

  A  224Rn β- decay (107 M) 

General Comments:

1981Ku02, 1969Ha03: 224Fr produced and identified in Th(p,X),E=600 MeV at ISOLDE-CERN facility. Measured β and γ radiation, half-life.

1964Bu02: searched for 224Fr activity but no evidence was found, authors estimated half-life to be <2 min

2014Kr09: mass determination with Penning-trap mass spectrometer ISOLTRAP facility at ISOLDE, CERN. Measured mass excess=21748 12.

2012Ch19 (also 2008ChZI): precise mass measurement by Schottky Mass Spectrometry

Theoretical calculations: 11 references extracted from the NSR database are listed in document records.

α 4.27 MeV 4 α group has been assigned to the decay of 228Ac with branching=5.5×10-8 22 per 228Ac decay in a chemically separated source (1969Lu12). This group would feed a level at 330 keV 42 in 224Fr. However, such a group would have an unreasonably low α hindrance factor, HF=4×10-4. Therefore, the assignment of this α group to the decay of 228Ac is considered as questionable by evaluators

Ten γ rays have been observed (1979Va20) in the decay of 224Rn, and are listed in the table, but no decay scheme has been proposed as yet. Evaluators note that a 202.21γ and 63.55γ cascade with 265.76γ as a crossover transition is suggested by 202.21 5 + 63.55 10=265.76 11 consistent with observed γ of 265.806 keV 17. Also, almost equal intensities of 260.581γ and 265.806γ suggest a cascade of these two gamma rays.

Q-value: S(2n)=10772 13, S(2p)=13782 19 (2021Wa16)

XREFJπ(level) T1/2(level)
  0.0A 1(-) 3.33 m 10 
% β- = 100

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Additional Level Data and Comments:

  0.01(-) 3.33 m 10 
% β- = 100
μ=+0.40 1 (1985Co24,2019StZV), Q=+0.523 9 (1985Co24,2021StZZ)
Measured δ<r2>=1.28937 4 relative to 212Fr (1987Co19) (correction of earlier value of 0.52269 2 quoted in 1985Co24). Other: 1.487 15 (2005Dz02).

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