Isobaric quartets in nuclei

Benenson, W.; Kashy, E.

doi:10.1103/revmodphys.51.527

Cited by 127 publications

(97 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Observed fragmented states have been removed from the present study since the IMME is based on an inherent one mass to one IAS relationship which does not hold in this case. In this simple analysis, we also leave aside the possibility of a zero-valued cubic term and a non-zero quartic contribution [9]. T = 3 2 data: 26 datasets are availaible of which two contain observed fragmented states, 6 with only 3 unambiguous data points, and 2 cases (A = 31 and A = 41) where the data precision ranges over three orders of magnitude and the calculation of the associated errors did not converge.…”

Section: Data Selectionmentioning

confidence: 99%

“…It is also thought that non-zero d-coefficients may arise in the case of mass shifts due to isospin mixing but may also be generated by charge-dependent nuclear forces, and/or three-body (or many-body) forces. Since the sixties many phenomenological studies have been devoted to reviewing and calculating these effects, for example [8,9,[16][17][18], but more recently extensive shell-model calculations in the f pshell [19] have become available. This present study is, in part, a complementary analysis to the most recent detailed experimental study in this mass region, involving new mass measurements [20] using innovative techniques.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Beyond the Isobaric Multiplet Mass Equation

MacCormick¹

2015

Proceedings of the Conference on Advances in Radioactive Isotope Science (ARIS2014)

View full text Add to dashboard Cite

Isospin is a fundamental symmetry in nature and can be used to gleam information on nuclear structure. Within the charge independence hypothesis of the nuclear force, the Coulomb energy component of nuclear mass can be described as an isospin dependent function through the Isobaric multiplet Mass Equation. This symmetry has been studied in a recent up-to-date and complete evaluation of ground state Isobaric Analogue State masses and the associated Isobaric Multiplet Mass Equation coefficients have been extracted. In this paper, isobaric multiplets beyond the standard first-order quadratic description are presented, and repercussions on future experimental programs are explored.

show abstract

Section: Data Selectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Beyond the Isobaric Multiplet Mass Equation

MacCormick¹

2015

Proceedings of the Conference on Advances in Radioactive Isotope Science (ARIS2014)

View full text Add to dashboard Cite

show abstract

“…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. 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%

“…Ref. [10] reported, in addition to the findings on 21 Mg, a new 20 Mg mass and a resulting IMME breakdown requiring a cubic term of 2.8(11) keV for the A = 20, T = 2 quintent. In this case, a recent experimental measurement of 20 Mg beta decay [16] used the superallowed 0 + → 0 + transition to the T = 2 20 Na IAS and the state's subsequent gamma decay to deduce an excitation energy for the IAS.…”

Section: Introductionmentioning

confidence: 99%

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

Bennett¹,

Wrede²,

Brown³

et al. 2016

Phys. Rev. C

View full text Add to dashboard Cite

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.

show abstract

“…1 Production of particles, pions or other hadrons, energetic photons or fast protons, in nucleus-nucleus collisions at energies per nucleon well below the free nucleon-nucleon threshold for such production [1] gives clear evidence for nucleonic correlations in nuclear matter. These correlations may simply reflect the fermionic nature of the nucleons or they may be seen as true collective effects, like clustering of nucleons (see [2] for a review).…”

Section: Introductionmentioning

confidence: 99%

Multiplicity distributions associated to subthreshold events in heavy-ion collisions

2001

View full text Add to dashboard Cite

Subthreshold events (pion production, for instance) at energies E < m π are treated as rare events. The associated multiplicity distribution P c (n) and the unconstrained distribution P (n), when there is no rare event-trigger, are related by the model independent relation P c (n) = n 2 n 2 P (n) .This relation, and in particular its improved version inspired in clustering of nucleons, is in fair agreement with data. Moreover, it allows to extract from the multiplicity data information on the number of nucleons involved in meson production processes, occuring at energies below the production threshold in free nucleon collisions.1 Production of particles, pions or other hadrons, energetic photons or fast protons, in nucleus-nucleus collisions at energies per nucleon well below the free nucleon-nucleon threshold for such production [1] gives clear evidence for nucleonic correlations in nuclear matter. These correlations may simply reflect the fermionic nature of the nucleons or they may be seen as true collective effects, like clustering of nucleons (see [2] for a review).By clustering processes we mean here pion production mechanisms involving sub-systems with a number of nucleons between 2 and the mass number A, the simplest example being the interaction of a nucleon with a deuteron. In fact, schematically we can represent pion production in the pd→ π 0 pd reaction via resonance formation as in the diagram of Fig.1a. The threshold for the mentioned reaction is lower than the free nucleon threshold (Fig.1b). In contrast to this diagram, the one of Fig.1a is kinematically allowed at subthreshold production energies, because the two nucleons of the deuteron are correlated. Basic diagrams [3][4][5][6], like the one in Fig.1b, require a medium to be non vanishing, for energies below the production energy threshold.Higher mass resonances can be obtained if larger clusters supply the required energy. Our emphasis here is on clustering rather than on the specific mechanism of pion production (like higher-mass resonances [7,8]) In order to see, in a simplified manner, what the problem is, let us write the laboratory energy E L of nucleus A aswhere E N is the average nucleon energy. If one assumes that a collision results from the superposition of nucleon-nucleon collisions and ignores Fermi momentum and binding energy, the threshold kinetic energy per nucleon to produce, say, a pion is,This is the free nucleon threshold. In nuclear matter one may have nucleons with energy above E N and the threshold becomes lower than (2). The lowering of the threshold (2) can be very easily visualized if one allows for clustering of nucleons. If α ≤ A nucleons of nucleus A -with mass number A-collide with one nucleon of nucleus B -with mass number B -(or vice-versa) the threshold energy per nucleon becomes,This is, of course, the threshold for free nucleon-nucleus collisions. As experimental production of pions occurs even at energies bellow m π , this requires clustering from both nuclei, α ≤ A and β ≤ B,with the absolute thr...

show abstract

Isobaric quartets in nuclei

Cited by 127 publications

References 35 publications

Beyond the Isobaric Multiplet Mass Equation

Beyond the Isobaric Multiplet Mass Equation

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

Multiplicity distributions associated to subthreshold events in heavy-ion collisions

Contact Info

Product

Resources

About