ADOPTED LEVELS for 191At

Author: V.R. Vanin Et Al. |  Citation: Nucl. Data Sheets 108, 2393 (2007) |  Cutoff date: 1-Dec-2006 

 Full ENSDF file | Adopted Levels (PDF version) 


S(p)= -1139 keV 21Q(α)= 7822 keV 14
Reference: 2012WA38

General Comments:

Identification: Observation of recoil-α-α correlations with 187Bi in the reaction 141Pr(54Fe,4n)191At (2002LeZZ).

Observation of α decay in fusion-evaporation measurements using the 141Pr(54Fe,4n) reaction at E=248-266 MeV, at mid-target. Gas-filled recoil fragment separator RITU. Recoil and α-ray detection by position-sensitive Si strip detector (2003Ke08,2005Ke10).

Levels: Levels proposed on the basis of recoil-tagged α-α coincidences, measured E(α), and considering α-decay links to levels in the daughter nuclide 187Bi. No γ-rays from 187Bi were observed due to poor statistics (2003Ke08).

Q-value: Note: Current evaluation has used the following Q record

Q-value: Q(α), S(p) estimated by evaluators on the basis of the mass excess data deduced from the α-decay studies in 2003Ke08. These values are consistent with the extrapolation of the available S(p) and Q(α) data in 2003Au03.

Q-value: Other: S(p)=-1020 140 keV (2005Ke10).





E(level)
(keV)
Jπ(level) T1/2(level)
   0.0 (1/2+) 1.7 ms +11-5 
% α ≈ 100
  55 30  (7/2-) 2.1 ms +4-3 
% α ≈ 100

Jπ(level): Proposed Jπ values from 191At α-decay experiments (2003Ke08).

T1/2(level): Values reported in 2003Ke08

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Additional Level Data and Comments:

E(level)Jπ(level)T1/2(level)Comments
   0.0(1/2+) 1.7 ms +11-5 
% α ≈ 100
Proposed as the 191At g.s. in 2003Ke08, 2005Ke10. This state decays with an ≈100% α branching to the ≈112 keV (1/2+) level in 187Bi by a transition for which 2003Ke08 tabulate Eα=7552 keV 11, HF=0.4 3. From the general trend for n=104 isotones in the neighborhood a value of r0(187Bi)=1.52 1 can be estimated. Using this, together with the other α ray data, a value of HF=0.38 25 is then obtained by the Preston method. This hindrance factor indicates an unhindered α transition. This is similar to the case of the neighboring 193At ground state. α value of δ2=150 100 keV for this transition is quoted in 2003Ke08 (see also 2005Uu03).
E(level): Proposed as the 191At g.s. in 2003Ke08, 2005Ke10. This state decays with an ≈100% α branching to the ≈112 keV (1/2+) level in 187Bi by a transition for which 2003Ke08 tabulate Eα=7552 keV 11, HF=0.4 3. From the general trend for n=104 isotones in the neighborhood a value of r0(187Bi)=1.52 1 can be estimated. Using this, together with the other α ray data, a value of HF=0.38 25 is then obtained by the Preston method. This hindrance factor indicates an unhindered α transition. This is similar to the case of the neighboring 193At ground state. α value of δ2=150 100 keV for this transition is quoted in 2003Ke08 (see also 2005Uu03).
  55(7/2-) 2.1 ms +4-3 
% α ≈ 100
This level decays by an α transition to the ≈63 keV (7/2-) level in 187Bi, and by a second α ray to the (9/2-) 187Bi ground state (2003Ke08). For these transitions 2003Ke08 tabulate the properties: 1) Eα=7653 keV 13, Iα=98% 2, HF=1.1 3; 2) Eα=7715 keV 15, Iα=2% 2, HF=50 50. Using the extrapolated value of r0(187Bi)=1.52 1, a recalculation of the hindrance factors using the Preston method leads to the values 0.98 22 and 74 80, respectively. α reduced α decay width of δ2=59 13 and 1.3 13 keV is reported in 2003Ke08 for the 7653 and 7715 keV α transitions, respectively (also in 2005Uu03 for the former transition).
E(level): This level decays by an α transition to the ≈63 keV (7/2-) level in 187Bi, and by a second α ray to the (9/2-) 187Bi ground state (2003Ke08). For these transitions 2003Ke08 tabulate the properties: 1) Eα=7653 keV 13, Iα=98% 2, HF=1.1 3; 2) Eα=7715 keV 15, Iα=2% 2, HF=50 50. Using the extrapolated value of r0(187Bi)=1.52 1, a recalculation of the hindrance factors using the Preston method leads to the values 0.98 22 and 74 80, respectively. α reduced α decay width of δ2=59 13 and 1.3 13 keV is reported in 2003Ke08 for the 7653 and 7715 keV α transitions, respectively (also in 2005Uu03 for the former transition).

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