Nuclear Electric Monopole Transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Ca</mml:mi></mml:mrow><mml:mrow><mml:mn>42</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>

Benczer‐Koller, N.; Nessin, M.; Kruse, T. H.

doi:10.1103/physrev.123.262

Cited by 23 publications

(6 citation statements)

References 15 publications

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“…In consequence the nu-._D clear transition time due to internal pair creation decreases also by 4 orders of magnitude in the considered Z range. Our calculated values for the inverse ratio l/r/ are compared in Table i with some available experimental data (see [13,22,23]) and with the calculations of Lombard [13]. 17 decreases by 7 orders of magnitude from oxygen (Z = 8) to polonium (Z= 84) mainly reflecting the change in the K-shell density distribution inside the nucleus.…”

Section: Results and Conclusionmentioning

confidence: 98%

Internal electron-positron pair production from electric monopole transitions

Soff¹,

Schlüter

Greiner

1981

Z Physik A

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Nuclear E0-transitions above the pair production threshold of co--2rn c2,-, 1 MeV are considered. The ration r/of the electron-positron pair creation probability to the K-shell conversion probability is calculated. For 92U and co= 1,450keV a typical value of t/ =2,10 .3 is obtained. Good agreement with experimental data is found. Our numerical results for finite size nuclei are compared with analytical expressions utilizing relativistic electron wavefunctions for point nuclei. The energy distributions of emitted positrons are presented for various nuclear charge values and transition energies. The possibility of monoenergetic positron emission is discussed. Of particular interest is the relation of the theoretical results to the recently observed structure in the positron spectra, which have been measured in high energy collisions of very heavy ions.

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Section: Results and Conclusionmentioning

confidence: 98%

Internal electron-positron pair production from electric monopole transitions

Soff¹,

Schlüter

Greiner

1981

Z Physik A

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“…[82]. The introduction of such a level does not affect the observed excitation pattern, as low-energy Coulomb excitation proceeds predominantly via E2 transitions; it, however, accounts for the alternative decay path of the 0 + 2 state.…”

Section: Coulomb-excitation Data Analysismentioning

confidence: 99%

“…1 electron intensities was determined to be equal to 1.03(10) in a (p,p ′ γ ) study [82]. This is equivalent to the I (E0; 0…”

Section: Coulomb-excitation Data Analysismentioning

confidence: 99%

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Quadrupole collectivity in Ca42 from low-energy Coulomb excitation with AGATA

Hadyńska-Klęk¹,

Napiórkowski²,

Zielińska³

et al. 2018

Phys. Rev. C

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K. HADYŃSKA-KLȨK et al. PHYSICAL REVIEW C 97, 024326 (2018) A Coulomb-excitation experiment to study electromagnetic properties of 42 Ca was performed using a 170-MeV calcium beam from the TANDEM XPU facility at INFN Laboratori Nazionali di Legnaro. γ rays from excited states in 42 Ca were measured with the AGATA spectrometer. The magnitudes and relative signs of ten E2matrix elements coupling six low-lying states in 42 Ca, including the diagonal E2 matrix elements of 2 + 1 and 2 + 2 states, were determined using the least-squares code GOSIA. The obtained set of reduced E2 matrix elements was analyzed using the quadrupole sum rule method and yielded overall quadrupole deformation for 0 + 1,2 and 2 + 1,2 states, as well as triaxiality for 0 + 1,2 states, establishing the coexistence of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in 42 Ca. The experimental results were compared with the state-of-the-art large-scale shell-model and beyond-mean-field calculations, which reproduce well the general picture of shape coexistence in 42 Ca.

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“…are also included in Table 1 [3] c From [4] basis of [1] and [17]. Numerical results, in tabular form, are given in [15].…”

Section: W (Eo) = Vv~( Eo) + Vv~(eo)= Z(eo) 'mentioning

confidence: 99%

First measurement ofK-shell-electron to internal-pair conversion probability ratios forE0 transitions inf p shell region

Passoja

1986

Z. Physik A - Atomic Nuclei

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Magnetic plus Si(Li) spectrometers designed for high-resolution conversion-electron and internal-pair measurements, are employed to obtain K-shell-electron to internal-pair conversion probability ratios for E0 transitions in 54Fe, 6~ 64Zn and V~ The results are found to be in good agreement with theoretical predictions. PACS: 23.20.Nx; 27.40. + z; 27.50. + eThe total E0 transition probability, neglecting twophoton and many-particle emissions, can be written in the form 1 W (EO) = VV~( EO) + VV~(EO)= z(EO) '(1) where z (E0) is the lifetime of the excited nucleus corresponding to the E0 transition, We is the total probability of electron conversion from different atomic shells, W. is the probability of internal pair formation. The electronic factors Or,. (Z, k) are associated with the electron transition probability from the K shell to the continuum state or with the formation of an electron-positron pair. These factors O~,.(Z, k) can be calculated for various models of the nuclear charge distribution, and are rather insensitive to the details of the model. Experimental K-shell-electron to internal-pair conversion probability ratios can be compared with the calculated ratios of Qr/O., since the monopole strength pZ(E0) is independent of the E0 decay mode. Experimental values for K-shell-electron to internal-pair conversion probability ratios have been obtained, for example, for E0 transitions in 160 [2], 4~ [3], 42Ca [4J and 9~ [3J. The lack of experimental data in the fp shell nuclei is due to difficulties in detecting weak E0 internal-pair transitions of 2-3 MeV energy. E0 internal-pair decay branches of the order of < 10 -3 and the fairly high level density in the fp shell nuclei make in E0 measurements a pair spectrometer with both a high resolution and a high electron-positron pair-collecting efficiency indispensable. All previous methods developed for in-beam studies of internal-pair transitions have difficulties with the pair-line efficiency; an increase of the efficiency has always led to a poor pair-line resolution [5][6][7].The present work was undertaken in order (i) to measure K-shell-electron to internal-pair conversion probability ratios for E0 transitions in 54Fe, 6~ 64Zn and 7~and (ii) to compare the experimental values with the theoretically predicted ratios. A new method for internal-pair spectrometry [8][9][10] featuring a unique combination of high resolution and efficiency has been used in these measurements: intermediate-image magnetic plus Si(Li) conversionelectron spectrometers [11][12] have been employed as conventional in-beam electron spectrometers and, after removal of baffles designed to stop positrons, as in-beam internal-pair spectrometers.The new method for high-resolution in-beam studies of internal-pair transitions [8][9][10] is based on the fact that the pair components (the electron and the positron) spiral, along the axial magnetic field, from the target to cooled Si(Li) detectors simultaneously, the sense of rotation being opposite. The energies of the particles are either ...

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Nuclear Electric Monopole Transition inCa42

Cited by 23 publications

References 15 publications

Internal electron-positron pair production from electric monopole transitions

Internal electron-positron pair production from electric monopole transitions

Quadrupole collectivity in Ca42 from low-energy Coulomb excitation with AGATA

First measurement ofK-shell-electron to internal-pair conversion probability ratios forE0 transitions inf p shell region

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