The Analysis of Angular Correlation and Angular Distribution Data

Abstract. The astrophysical S(E) factor of14 N(p, γ) 15 O has been measured for effective center-of-mass energies between E ef f = 119 and 367 keV at the LUNA facility using TiN solid targets and Ge detectors. The data are in good agreement with previous and recent work at overlapping energies. R-matrix analysis reveals that due to the complex level structure of 15 O the extrapolated S(0) value is model dependent and calls for additional experimental efforts to reduce the present uncertainty in S(0) to a level of a few percent as required by astrophysical calculations. .KvX -and γ ray spectroscopy -97.10.CvStellar structure and evolution PACS

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“…where a k are the angular distribution coefficients and Q k the attenuation coefficients calculated according to [22]. 1.E-02…”

Section: Angular Distributionsmentioning

confidence: 99%

S-factor of 14N(p,γ)15O at astrophysical energies⋆

et al. 2005

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“…[17,18], using the computer code COR-LEONE [19,20]. The code takes into account the attenuation factors of the detectors [21,22]. An example of a γγ angular correlations analysis is shown in Fig.…”

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confidence: 99%

Evidence for shape coexistence in98Mo

et al. 2013

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A γγ angular correlation experiment has been performed to investigate the low-energy states of the nucleus 98 Mo. The new data, including spin assignments, multipole mixing ratios and lifetimes reveal evidence for shape coexistence and mixing in 98 Mo, arising from a proton intruder configuration. This result is reproduced by a theoretical calculation within the proton-neutron interacting boson model with configuration mixing, based on microscopic energy density functional theory. The microscopic calculation indicates the importance of the proton particle-hole excitation across the Z = 40 sub-shell closure and the subsequent mixing between spherical vibrational and the γ-soft equilibrium shapes in 98 Mo.PACS numbers: 21.60. Jz, 21.60.Fw, 23.20.En, 27.80.+w For decades, to clarify the nature of shape coexistence has been one of the major objectives in nuclear structure physics [1,2]. The phenomenon has been observed in various regions of the nuclear chart, from light The A ∼ 100 mass region also presents a unique laboratory for the evolution of nuclear shape and shape coexistence [6,7]. The interplay between single-particle and collective degrees of freedom leads to shape phase transitions along isotopic and isotonic chains [8]. The most dramatic examples for shape coexistence and shape transition occur in the Zr isotopic chain, as recently revealed for 94 Zr [9]. Especially in the N = 50−56 Zr isotopes the 0 + 1 state and the very low-lying 0 + 2 state are considered strongly mixed 0p-0h and 2p-2h proton configurations, where protons are promoted from the pf shell to the g 9/2 orbital, as also found in shell model calculations [6,10]. The structure of the low-lying 0 + 2 state in N ≥ 58 Zr isotopes is somewhat more complicated due to neutron contributions. In Mo isotopes, starting from N = 50 the nuclear shape gradually evolves from a sphere and, driven by the enhanced proton-neutron residual interac- * tim.thomas@ikp.uni-koeln.de tion, large deformation sets in at N ≈ 60 [11]. Situated in between, 98 42 Mo 56 is pivotal for understanding shape transitions in this mass region. In particular, the concept of shape coexistence can apply to this nucleus, where proton cross-shell excitations from the Z = 28 − 40 pf shell to the πg 9/2 orbit may play an important role [12]. In fact, experimentally, the first excited state of 98 Mo has been shown to be an coexisting isomeric 0 + state of different shape [13,14]. The mixing between the proton 2p-0h and 4p-2h configurations forms the first excited 0 + state and the ground state as revealed by the investigation of γ transitions depopulating 1 + states with equal strengths to both 0 + states [12], akin to the findings for 92 Zr [6].To address the important issue of the nature of lowlying structure in 98 Mo, we performed a γγ angular correlation experiment. In this paper, the results of this experiment are reported as well as the identification of shape coexistence and the role of a proton intruder configuration in 98 Mo. events were collected using a γγ coincidence tri...

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“…, where a 2 is the anisotropy coefficient and Q 2 is an attenuation factor for the finite γ-ray counter [31] (0.98 in our case). From a best fit to the data, shown with a solid (dashed) line for the 40 Ca+ 152 Sm ( 48 Ca+ 144 Sm) reaction, we found a 2 = -0.13 ± 0.03 for the 40 Ca+ 152 Sm reaction and a 2 = -0.06 ± 0.02 for the 48 Ca+ 144 Sm one.…”

Section: Fusion-evaporation Resultsmentioning

confidence: 99%

Dynamical Dipole mode in heavy-ion fusion reactions

et al. 2017

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Abstract. The excitation of the Dynamical Dipole mode along the fusion path was investigated for the first time in the formation of a heavy compound nucleus in the A∼190 mass region. The compound nucleus was formed at identical conditions of excitation energy and spin from two entrance channels having different charge asymmetry: the charge asymmetric 40 Ca + 152 Sm and the nearly charge symmetric 48 Ca + 144 Sm at E lab =11 and 10.1 MeV/nucleon, respectively. Both fusion-evaporation and fission events were studied simultaneously for the first time. The Dynamical Dipole mode excitation in the charge asymmetric channel was evidenced, in a model-independent way, by comparing the γ-ray multiplicity spectra and angular distributions of the two entrance channels with each other.

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The Analysis of Angular Correlation and Angular Distribution Data

Cited by 616 publications

References 5 publications

S-factor of 14N(p,γ)15O at astrophysical energies⋆

S-factor of 14N(p,γ)15O at astrophysical energies⋆

Evidence for shape coexistence in98Mo

Dynamical Dipole mode in heavy-ion fusion reactions

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