Beta decay of 31Ar

Axelsson, L.; Äystö, J.; Borge, M. J. G.; Fraile, L. M.; Fynbo, H. O. U.; Honkanen, A.; Hornshøj, P.; Jokinen, A.; Jonson, B.; Lipas, P.O.; Martel, I.; Mukha, I.; Nilsson, T.; Nyman, G.; Petersen, B.; Riisager, K.; Smedberg, M. H.; Tengblad, O.

doi:10.1016/s0375-9474(98)00172-9

Cited by 46 publications

(61 citation statements)

References 36 publications

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“…[30], with the new high-precision 31 Cl mass excess, a fit of the quadratic IMME fails, requiring a large coefficient for the cubic term, d = −3.5(11) keV. Using our value of 6279.0(6) keV for the observed IAS excitation energy, the quadratic fit also fails, requiring a coefficient for the cubic term of d = −4.3 (11) keV.…”

Section: Immementioning

confidence: 81%

“…[30] and the other, precisely known values for 31 Si and 31 P [43]. However, this does little to fix the breakdown problem: the reduced chisquared value of the quadratic fit actually increases from χ 2 /ν = 11.6, in Ref.…”

Section: Immementioning

confidence: 97%

“…A 1977 experimental measurement of the 36 Ar( 3 He, 8 Li) 31 Cl Q-value resulted in a mass excess value of ∆ = −7070 ± 50 keV [20]. Subsequent evalutions of the IMME [6][7][8]21] 31 Si [27][28][29]), the 50-keV uncertainty in the 31 Cl mass excess has hindered attempts to test the IMME stringently in the lowest quartet.…”

Section: Introductionmentioning

confidence: 99%

“…Subsequent evalutions of the IMME [6][7][8]21] 31 Si [27][28][29]), the 50-keV uncertainty in the 31 Cl mass excess has hindered attempts to test the IMME stringently in the lowest quartet. A recent Penning trap mass measurement of 31 Cl finally obtained a value for the ground state mass excess 15 times more precise than previous estimates [30], leading to an IMME breakdown in the lowest quartet; the IMME fit required an unusually large cubic term, with d = −3.5(11) keV.…”

Section: Introductionmentioning

confidence: 99%

“…In fact, a tentative measurement of the first 31 Cl excited state via 31 Ar β decay [31] was the only evidence for the observation of that state [32] until a recent Coulombbreakup experiment was performed to confirm the existence of the state [33]. The excitation energy was found in Ref.…”

Section: Introductionmentioning

confidence: 99%

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Isobaric multiplet mass equation in theA=31,T=3/2quartets

Bennett¹,

Wrede²,

Brown³

et al. 2016

Phys. Rev. C

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Background: The observed mass excesses of analog nuclear states with the same mass number A and isospin T can be used to test the isobaric multiplet mass equation (IMME), which has, in most cases, been validated to a high degree of precision. A recent measurement (Kankainen et al., Phys. Rev. C 93 041304(R) (2016)) of the ground-state mass of 31 Cl led to a substantial breakdown of the IMME for the lowest A = 31, T = 3/2 quartet. The second-lowest A = 31, T = 3/2 quartet is not complete, due to uncertainties associated with the identity of the 31 S member state.Purpose: To populate the two lowest T = 3/2 states in 31 S and use the data to investigate the influence of isospin mixing on tests of the IMME in the two lowest A = 31, T = 3/2 quartets.Methods: Using a fast 31 Cl beam implanted into a plastic scintillator and a high-purity Ge γ-ray detection array, γ rays from the 31 Cl(βγ) 31 S sequence were measured. Shell-model calculations using USDB and the recently-developed USDE interactions were performed for comparison.Results: Isospin mixing between the 31 S isobaric analog state (IAS) at 6279.0(6) keV and a nearby state at 6390.2(7) keV was observed. The second T = 3/2 state in 31 S was observed at Ex = 7050.0(8) keV. Calculations using both USDB and USDE predict a triplet of isospin-mixed states, including the lowest T = 3/2 state in 31 P, mirroring the observed mixing in 31 S, and two isospin-mixed triplets including the second-lowest T = 3/2 states in both 31 S and 31 P.Conclusions: Isospin mixing in 31 S does not by itself explain the IMME breakdown in the lowest quartet, but it likely points to similar isospin mixing in the mirror nucleus 31 P, which would result in a perturbation of the 31 P IAS energy. USDB and USDE calculations both predict candidate 31 P states responsible for the mixing in the energy region slightly above Ex = 6400 keV. The second quartet has been completed thanks to the identification of the second 31 S T = 3/2 state, and the IMME is validated in this quartet.

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Section: Immementioning

confidence: 81%