List of levels for 191AT

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 21	Q(α)= 7822 keV 14
Reference: 2012WA38

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).

J^π	T_1/2/Decay

E(level) (keV)	J^π(level)	T_1/2(level)
0.0	(1/2+)	1.7 ms +11-5 % α ≈ 100
55 30	(7/2-)	2.1 ms +4-3 % α ≈ 100

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

T_1/2(level): Values reported in 2003Ke08

E(level)	J^π(level)	T_1/2(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).