Azimuthal asymmetry of direct photons in intermediate energy heavy-ion collisions

Liu, GH; Ma, Yugang; Xiang-Zhou, Cai; Fang, DQ; Shen, W. Q.; Tian, Wenlong; Wang, K

doi:10.1016/j.physletb.2008.04.037

Cited by 21 publications

(9 citation statements)

References 40 publications

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“…More details of the model can be found in Refs. [11,17]. The probability for emitting a photon in a single p-n collision can be written as…”

Section: Re-extract Nucleon's Kinetic Energy Considering Dynamic mentioning

confidence: 99%

“…frame and the velocity of the γ-emission source is close to half of the beam's velocity. Such a fact strongly suggests the incoherent proton-neutron (p-n) collision during the early stage of nuclear interaction is dominated for the hard photon bremsstrahlung [15][16][17][18][19]. Based on this mechanism, the inverse slope of hard photons could be taken as a measure of the energy and momentum distributions of nucleons which are responsible for hard photon production [2,3,20].…”

Section: Introductionmentioning

confidence: 99%

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Direct photon emission and influence of dynamical wave packets in an extended quantum molecular dynamics model

Shi

Cao

et al. 2020

Phys. Rev. C

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Direct photon produced from first proton-neutron (p-n) collision during the early stage of heavy ion reaction is a sensitive probe to reflect energy and momentum distribution of nucleons. In this work, we embedded the hard photon production channel in an extended quantum molecular dynamics (EQMD) model, and took the direct photon as a possible probe to improve namely the Fermi motion in the EQMD model. A possible scheme is offered to handle the dynamical wave packet width within incoherent bremsstrahlung process. Direct photons calculated by our modified EQMD were compared with data of 14 N + 12 C at beam energies E/A = 20, 30 and 40 MeV, and it is found that the yield, inverse slope and angular distribution of direct photons could be reasonably reproduced. In addition, asymmetric reaction systems of 4 He + C and 4 He + Zn at E/A = 53 MeV are also simulated in this work. It is found that the symmetric angular distribution in the nucleon-nucleon (N-N) center-of-mass (c.m.) frame and the velocity of theγ-emission source can be reasonably obtained from our method although there is some quantitative differences.

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“…More details of the model can be found in Refs. [11,17]. The probability for emitting a photon in a single p-n collision can be written as…”

Section: Re-extract Nucleon's Kinetic Energy Considering Dynamic mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Direct photon emission and influence of dynamical wave packets in an extended quantum molecular dynamics model

Shi

Cao

et al. 2020

Phys. Rev. C

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“…For example, the TAPS collaboration has done a series of experiments investigating properties of hot and dense matter using hard photons as messengers [79][80][81][82]. Theoretically, it was concluded that neutron-proton bremsstrahlungs in the early stage of the reaction are the main source of high energy photons [83,84]. It was also demonstrated that hard photon productions in heavy-ion collisions can be used to probe the reaction dynamics leading to the formation of dense matter [85][86][87][88][89].…”

Section: The Brief Description Of the Updated Ibuu Transport Modelmentioning

confidence: 99%

Interplay of short-range correlations and nuclear symmetry energy in hard-photon production from heavy-ion reactions at Fermi energies

Yong

2017

Phys. Rev. C

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Within an isospin-and momentum-dependent transport model for nuclear reactions at intermediate energies, we investigate the interplay of the nucleon-nucleon short-range correlations (SRC) and nuclear symmetry energy Esym(ρ) on hard photon spectra in collisions of several Ca isotopes on 112 Sn and 124 Sn targets at a beam energy of 45 MeV/nucleon. It is found that over the whole spectra of hard photons studied, effects of the SRC overwhelm those due to the Esym(ρ). The energetic photons come mostly from the high-momentum tails (HMT) of single-nucleon momentum distributions in the target and projectile. Within the neutron-proton dominance model of SRC based on the consideration that the tensor force acts mostly in the isosinglet and spin-triplet nucleon-nucleon interaction channel, there are equal numbers of neutrons and protons, thus a zero isospin-asymmetry in the HMTs. Therefore, experimental measurements of the energetic photons from heavy-ion collisions at Fermi energies have the great potential to help us better understand the nature of SRC without any appreciable influence by the uncertain Esym(ρ). These measurements will be complementary to but also have some advantages over the ongoing and planned experiments using hadronic messengers from reactions induced by high-energy electrons or protons. Since the underlying physics of SRC and Esym(ρ) are closely correlated, a better understanding of the SRC will in turn help constrain the nuclear symmetry energy more precisely in a broad density range.

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“…However, compared with nucleons, light fragments and projectile-like fragments produced in the reaction, hard photons have a considerable advantage not being disturbed by the final-state interactions. Therefore, hard photons provide a clean probe of the reaction dynamics and deliver an unperturbed picture of the emitting source [28][29][30][31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Effects of neutron-skin thickness on direct hard photon emission from reactions induced by the neutron-rich projectile $^{50}$Ca

Wang,

Ma,

Fang

et al. 2022

Preprint

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Direct hard photon emissions from incoherent proton-neutron bremsstrahlung in the collisions of neutron-rich projectile 50 Ca with 12 C and 40 Ca targets are simulated in the framework of IQMD model, respectively. By adjusting the diffuseness parameter of neutron density in the droplet model to obtain different neutron skin thickness for 50 Ca, the effects of neutron skin thickness on direct hard photon emission are investigated via several probes. The results show that more direct hard photons are produced with the increasing of the neutron skin thickness. Meanwhile, we find that yield ratio Rcp(σγ) and the rapidity dependence of multiplicity and multiplicity ratio Rcp(Nγ) for direct hard photons are apparently sensitive to neutron skin thickness. Furthermore, the direct hard photon differential and relative flows between central and peripheral collision are presented. We find that the differential flow is slightly more sensitive to neutron skin thickness than the relative flow. It is suggested that direct hard photon emission may be used as an experimental observable to extract the information of neutron skin thickness.

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Azimuthal asymmetry of direct photons in intermediate energy heavy-ion collisions

Cited by 21 publications

References 40 publications

Direct photon emission and influence of dynamical wave packets in an extended quantum molecular dynamics model

Direct photon emission and influence of dynamical wave packets in an extended quantum molecular dynamics model

Interplay of short-range correlations and nuclear symmetry energy in hard-photon production from heavy-ion reactions at Fermi energies

Effects of neutron-skin thickness on direct hard photon emission from reactions induced by the neutron-rich projectile $^{50}$Ca

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