Knockout of proton-neutron pairs from 16O with electromagnetic probes

Middleton, D. G.; Annand, J. R. M.; Barbieri, C.; Giusti, C.; Grabmayr, P.; Hehl, T.; MacGregor, I. J. D.; Martin, Ian; McGeorge, J. C.; Moschini, F.; Pacati, F.D.; Schwamb, M.; Watts, D. P.

doi:10.1140/epja/i2009-10902-7

Cited by 8 publications

(6 citation statements)

References 49 publications

(84 reference statements)

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“…A similar two-nucleon knockout study can also be performed using an 16 O projectile, for which np pair knockout using electromagnetic probes has been measured [37,38] and supports the SRC observations for 12 C. In this case, the 14 O residue is also of interest, given that only the 0 + ground state is bound, and where the results of Refs. [13,36] indicate a correspondingly small cross section and a narrow momentum distribution, consistent with theoretical expectations.…”

Section: Discussionsupporting

confidence: 66%

Two-nucleon correlation effects in knockout reactions fromC12

Simpson

Tostevin

2011

Phys. Rev. C

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Reactions that involve the direct and sudden removal of a pair of like or unlike nucleons from a fast projectile beam by a light target nucleus are considered. Specifically, we study the three two-nucleon removal channels from 12 C that populate final states in the 10 Be, 10 B, and 10 C reaction residues. The calculated two-nucleon removal cross sections and the residue momentum distributions are compared with available high-energy data at 250, 1050, and 2010 MeV per nucleon, i.e., data that are inclusive with respect to the bound final states of the residues. The measured np removal cross sections only are significantly greater than the values calculated, suggesting that the reaction mechanism observes enhanced np spatial correlations compared to those present in the shell-model wave functions.

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Section: Discussionsupporting

confidence: 66%

Two-nucleon correlation effects in knockout reactions fromC12

Simpson

Tostevin

2011

Phys. Rev. C

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“…3NFs also reduce the average energy separation of the two major valence shell, sd and pf, by a factor of two and bring these in closer agreement with the experiment. In our calculations we find that the neutron separation energy to the J π = 3/2 + state of 43 Ca is about -16 MeV. This is close to the phenomenological predictions based on the DOM of Ref.…”

Section: Studies Of Correlations and Optical Potentialssupporting

confidence: 89%

“…Thus, in general, a full FRPA calculation involves the calculations of the particle-hole (ph) response and of the two-body spectral function. The latter has been employed, for example, to investigate nuclear correlations from two-nucleon emission experiments [41,42,43]. The difference between the two approaches is in the fact that vibrations in the ph and particle-particle/hole-hole (pp/hh) channels are calculated in Tamn-Dancoff approximation for ADC(3) and in random phase approximation for FRPA.…”

Section: Second-order Self-energiesmentioning

confidence: 99%

Many-body Propagator Theory with Three-Body Interactions: a Path to Exotic Open Shell Isotopes

Barbieri

2014

J. Phys.: Conf. Ser.

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Ab-initio predictions of nuclei with masses up to A∼100 or more are becoming possible thanks to novel advances in computations and in the formalism of many-body physics. Some of the most fundamental issues include how to deal with many-nucleon interactions, how to calculate degenerate-open shell-systems, and pursuing ab-initio approaches to reaction theory. Self-consistent Green's function (SCGF) theory is a natural approach to address these challenges. Its formalism has recently been extended to three-and many-body interactions and reformulated within the Gorkov framework to reach semi-magic open shell isotopes. These exciting developments, together with the predictive power of chiral nuclear Hamiltonians, are opening the path to understanding large portions of the nuclear chart, especially within the sd and pf shells. The present talk reviews the most recent advances in ab-initio nuclear structure and many-body theory that have been possible through the SCGF approach.A second and major challenge to ab-initio theory is that standard implementations of the above methods are limited to doubly closed (sub-)shell nuclei and to their immediate neighbors [23,14]. As one increases the nuclear mass, longer chains of truly open shell nuclei emerge that cannot be accessed with these approaches. Many-body techniques that could tackle genuine open shell systems-or, at least, singly open shells-would immediately extend the reach of ab-initio studies from a few tens to several hundreds of mid-mass isotopes. Our collaboration has proposed to exploit ideas based on breaking particle-number symmetry in order to achieve this goal [24,25,26]. This has led to reformulating the SCGF in the Gorkov formalism (Gorkov-GF) [26,27,28], which will be discussed in this talk. Applications of Gorkov-GF have been successful for the Ca and neighbouring isotopes up to 54 Ti [29]. Recently, similar developments have also been introduced within the IMSRG framework [13].The last challenge to theory is to provide consistent descriptions of the structure and reactions of nuclei in order to constrain and improve the analysis of experimental data. Microscopic calculations of elastic nucleon scattering were achieved, e.g., for a 16 O target in [30,31]. Recently, ab-initio calculations, including cluster projectiles, have been possible for few-body targets by combining the ab-initio no-core shell model (NCSM) with the resonating-group method (RGM) [32,33]. For larger masses, the SCGF becomes the method of choice due to the equivalence between the many-body self-energy and Fesbach theory of elastic scattering. This fact has guided recent advances of phenomenological dispersive optical models (DOM) [34,35] and microscopic calculations of optical potentials [2,30,36]. Further developing these approaches to proper ab-initio methods will be crucial to advance our understanding of exotic radioactive beam experiments.This talk reports about recent progress on the above topics within the SCGF approach to quantum many-body physics. The new details of the formalis...

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“…In reality, the 2h strength corresponding with (n 1 l 1 ) −1 (n 2 l 2 ) −1 extends over a wide energy range [38]. Current A(e, e pN ) measurements are performed at Q 2 -values of the order of GeV 2 not allowing one to measure cross sections for real exclusive processes as could be done at lower Q 2 values [26,39,40]. Accordingly, rather than probing the individual 2h contributions to P 2 , the measured semi-inclusive A(e, e pN ) cross sections can be linked to the P 2 (P 12 | nl = 00) which involves a summation over the 2h states.…”

Section: Ho Wsmentioning

confidence: 99%

Factorization of exclusive electron-induced two-nucleon knockout

et al. 2014

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We investigate the factorization properties of the exclusive electroinduced two-nucleon knockout reaction A(e,e pN). A factorized expression for the cross section is derived and the conditions for factorization are studied. The A(e,e pN) cross section is shown to be proportional to the conditional center-of-mass (c.m.) momentum distribution for close-proximity pairs in a state with zero relative orbital momentum and zero radial quantum number. The width of this conditional c.m. momentum distribution is larger than the one corresponding with the full c.m. momentum distribution. It is shown that the final-state interactions (FSIs) only moderately affect the shape of the factorization function for the A(e,e pN) cross sections. Another prediction of the proposed factorization is that the mass dependence of the A(e,e pp) [A(e,e pn)] cross sections is much softer than[NZ].

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Knockout of proton-neutron pairs from 16O with electromagnetic probes

Cited by 8 publications

References 49 publications

Two-nucleon correlation effects in knockout reactions fromC12

Two-nucleon correlation effects in knockout reactions fromC12

Many-body Propagator Theory with Three-Body Interactions: a Path to Exotic Open Shell Isotopes

Factorization of exclusive electron-induced two-nucleon knockout

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