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The mass dependence of the transverse flow for $Z=1$--5 fragments from the collisions of $^{40}\mathrm{Ar}+^{27}\mathrm{Al}, ^{40}\mathrm{Ar}+^{48}\mathrm{Ti}$, and $^{40}\mathrm{Ar}+^{58}\mathrm{Ni}$ at 47 MeV/nucleon is investigated experimentally in this article. The transverse flow values are determined using the in-plane components of the fragment transverse momenta, where three conventional methods, i.e., the kinetic flow tensor method, the transverse momentum analysis method, and the azimuthal correlation method, are applied to reconstruct the reaction plane in an event-by-event basis. It is demonstrated from the comparison of the present experimental mass dependent flow measurements and the model simulations using an improved antisymmetrized molecular dynamics model that the experimentally observed abnormal $\ensuremath{\alpha}$ transverse flow enhancement is closely related to the reaction plane reconstruction procedure in the flow extraction. We further investigate the physical existence of the abnormal $\ensuremath{\alpha}$ flow behavior using a two-particle azimuthal correlation method, which allows us to provide the relative flow magnitude information with an identification of fragment charge number without the knowledge of the reaction plane differing from the three conventional methods. It is found that the relative flow magnitudes deduced from the two-particle azimuthal correlation functions with an identification of $Z$, with the correction for the recoil effect imposed by the momentum conservation, show a monotonically increasing trend as a function of fragment charge number, with no exception of the $\ensuremath{\alpha}$ flow enhancement. These results, in addition to those from the improved antisymmetrized molecular dynamics model simulations, definitely provide experimental evidences for the inexistence of the abnormal $\ensuremath{\alpha}$ flow behavior in the heavy-ion collisions at the present incident energy region in nature.

The neutron capture cross section of $$^{197}\hbox {Au}$$ was measured using the time-of-flight (TOF) technique at the Back-n facility of the China Spallation Neutron Source (CSNS) in the 1 eV to 100 keV range. Prompt $$\gamma $$ -rays originating from neutron-induced capture events were detected by four C $$_{6}$$ D $$_{6}$$ liquid scintillator detectors. Pulse height weighting technology (PHWT) was used to analyze the data. The results are in good agreement with ENDF/B-VIII.0, CENDL-3.1, and other evaluated libraries in the resonance region, and in agreement with both n $$\_$$ TOF and GELINA experimental data in the 5–100 keV range. Finally, the resonance peaks in the energy range from 1 eV to 1 keV were fitted by the SAMMY R-matrix code.

The experimentally observed abnormal $\ensuremath{\alpha}$ flow behavior from heavy-ion collisions at intermediate energies is investigated using the events of $^{40}\mathrm{Ca}+^{40}\mathrm{Ca}$ at 35 MeV/nucleon simulated with an improved antisymmetrized molecular dynamics model with specific consideration of the Fermi motion in the nucleon-nucleon collision process. Its possible origins in the processes from the fragment formation to the experimental flow extraction, i.e., dynamical process, sequential decay, experimental detection, and data analysis, are closely examined. It is found that the observed abnormal $\ensuremath{\alpha}$ flow behavior originates from the reconstruction of reaction planes in the flow extraction. How the abnormal $\ensuremath{\alpha}$ flow behavior is generated from the reaction plane reconstruction procedure is discussed.

We propose a hybrid approach between the sudden model and the adiabatic model to explain the fusion hindrance in heavy-ion fusion reactions at deep subbarrier energies. Due to the strong Pauli blocking effects at the density overlap region, the $\ensuremath{\alpha}$ particle approaching the target $^{208}\mathrm{Pb}$ becomes enlarged and its density distribution gets changed. By introducing energy dependence into this density variation effect, the potentials at different colliding energies are diverse. With the decrease of colliding energies, the significantly enhanced density variation effects make the nuclear potential more attractive and result in a deeper pocket in the inner part. A reasonable description of the experimental fusion cross sections is achieved for the $\ensuremath{\alpha} + ^{208}\mathrm{Pb}$ reaction. On account of highlighting the influence of density variation effects on the fusion process at deep subbarrier energies, we further investigate the density variation effects in the $^{16}\mathrm{O} + ^{208}\mathrm{Pb}$ fusion reaction based on the $\ensuremath{\alpha}$-cluster structures in $^{16}\mathrm{O}$ nuclei. The fusion hindrance at deep subbarrier energies is described well by considering the density variation effects. In addition, an astrophysical $S$ factor between the sudden model and adiabatic model is predicted at the energies below the experimental data.

Anisotropic flow can offer significant information of evolution dynamics in heavy-ion collisions. A systematic study of the directed flow $v_1$ and elliptic flow $v_2$ of hard photons and free nucleons is performed for $^{40}$Ca+$^{40}$Ca collisions in a framework of isospin dependent quantum molecular dynamics (IQMD) model. The study firstly reveals that thermal photons emitted in intermediate-energy heavy-ion collisions have the behaviors of directed and elliptic flows. The interesting phenomena of incident energy dependence of $v_1$ and $v_2$ for thermal photons in central collisions also confirmed that it can be regarded as a good probe of evolution dynamics. Moreover, the multiplicities of hard photons and free nucleons and their correlation are also investigated. We find that direct photon emission is positively related to free nucleons emission, however, there exists an anti-correlation for thermal photons with free nucleons., 9 pages, 10 figures

In this study, the Pauli blocking potential between two colliding nuclei in the density overlapping region is applied to describe the heavy nuclei fusion process. Inspired by the Pauli blocking effect in the -decay of heavy nuclei, the Pauli blocking potential of single nucleon from the surrounding matter is obtained. In fusion reactions with strong density overlap, the Pauli blocking potential between the projectile and target can be constructed using a single folding model. By considering this potential, the double folding model with a new parameter set is employed to analyze the fusion processes of 95 systems. A wider Coulomb barrier and shallower potential pocket are formed in the inner part of the potential between the two colliding nuclei, compared to that calculated using the Akyüz-Winther potential. The fusion hindrance phenomena at deep sub-barrier energies are described well for fusion systems O + Pb and Ni + Ni.

Theoretical prediction shows that about 9000 nuclei could be bounded, of which the properties will be hot topics in the new nuclear physics era opened by the new third generation of radioactive nuclear beam (RNB) facilities. Projectile fragmentation reactions are important to produce rare nuclei with extreme large N / Z asymmetry even to the drip lines. Variety of key questions in nuclear physics, for example, the nuclear Equation of State, the extreme of nuclides at drip lines, the shell evolution, etc, are hoped to be answered. A review is presented on the topic related to projectile fragmentation reactions, including the historical review of RNB facilities, the characteristics of modern RNB facilities, the particle identification techniques for searching rare isotopes in RNB experiments and benchmark projectile fragmentation reactions. Furthermore, the theory reviews for fragment production predictions are also made, which include the empirical formula, transport models, statistical models, machine learning methods, etc. Some important probes to nuclear properties have also been presented, which are the temperature/thermometer, the isoscaling, the isobaric ratio difference scaling, the neutron-skin thickness, etc.

A Compact Spectrometer for Heavy IoN Experiments (CSHINE) has been recently built for the studies of heavy ion reactions at intermediate energies. CSHINE consists of a Si-Si-CsI telescope array and a parallel plate avalanche counter (PPAC) array. Each telescope consists of a thin single-sided silicon strip detector and a thick double-sided silicon strip detector backed by a 3 × 3 CsI(Tl) crystal hodoscope . The thicknesses of the silicon detectors are optimized in order to identify various types of light charged particles in a wide energy range. PPAC is a large-area two-dimensional position-sensitive gas detector, which records fission fragments with the intrinsic efficiency of approximately 100% but filters out light charged particles at properly selected working conditions. In the phase-II run, four Si-Si-CsI telescopes and three PPACs have been installed and operated in the beam experiment with 25 MeV/u Kr+Pb reactions. Particle identification for isotopes from Hydrogen to Boron has been achieved with the Si-Si-CsI telescopes, while excellent timing and position resolution have been achieved with the PPACs.

Fragments productions in spallation reactions are key infrastructure data for various applications. Based on the empirical parameterizations {\sc spacs}, a Bayesian-neural-network (BNN) approach is established to predict the fragment cross sections in the proton induced spallation reactions. A systematic investigation have been performed for the measured proton induced spallation reactions of systems ranging from the intermediate to the heavy nuclei and the incident energy ranging from 168 MeV/u to 1500 MeV/u. By learning the residuals between the experimental measurements and the {\sc spacs} predictions, the BNN predicted results are in good agreement with the measured results. The established method is suggested to benefit the related researches in the nuclear astrophysics, nuclear radioactive beam source, accelerator driven systems, and proton therapy, etc., Comment: 7 figures, accepted by Chinese Physics C

A scaling phenomenon has been found for the cross section of a fragment, which is defined as a “square” cross section (SCS). This phenomenon can unify the cross sections of fragments in projectile fragmentation (PF) reactions. An empirical formula is proposed to calculate SCS for a fragment with parameters determined by an extensive investigation of measured reactions ranging from Fermi energies to relativistic energies. The scaling phenomenon of SCS has been verified using different techniques, showing that the scaling of SCS generally exists in PF reactions. The concept of SCS, which can be assumed as a standard value for a fragment, is shown to accurately predict the cross sections of isotopes in PF reactions with incident energies ranging from tens of A MeV to approximately 1000A MeV.

An isoratio method is proposed to study the chemical potential of neutrons (protons) from the yield ratio of isotopes (isotones) differing in neutron-excess (I = N − Z). The measured fragments in the 140 A MeV 40,48Ca and 58,64Ni + 9Be reactions, as well as those in the simulated 58,64Ni + 9Be reactions by using the antisymmetric molecular dynamics (AMD) model plus the secondary decay model gemini, have been adopted to perform the isoratio analysis. The results of the isoratio method verify that they are similar to that of the well known isoscaling method. The isoratio scaling phenomenon suggested by the isoratio method has also been found in the measured data and the fragments simulated by the AMD + gemini models.

An isoratio method, i.e., the isotopic (isotonic) ratio among three isotopes (isotones), is proposed to study the free energy and temperature effects in the intermediate mass fragments produced in heavy-ion collisions. The parameterizations for the free energy of nucleus at low temperature, which have been proposed in the framework of the density functional theory using the SKM skymre interaction, are adopted to calculate the temperature-dependent free energy of fragment. By analyzing the measured yields of fragments in the 140A MeV 58,64Ni + 9Be reactions, it is verified that the free energy in the isoratio is almost the same for different reactions. A temperature-dependent pairing-energy is introduced into the parameterizations for free energy, which reveals that the weakened pairing energy at the low temperature accounts for the weakened or disappearing odd-even staggering in isoratio.

Complementary metal-oxide-semiconductor (CMOS) sensors can convert X-rays into detectable signals; therefore, they are powerful tools in X-ray detection applications. Herein, we explore the physics behind X-ray detection performed using CMOS sensors. X-ray measurements were obtained using a simulated positioner based on a CMOS sensor, while the X-ray energy was modified by changing the voltage, current, and radiation time. A monitoring control unit collected video data of the detected X-rays. The video images were framed and filtered to detect the effective pixel points (radiation spots). The histograms of the images prove there is a linear relationship between the pixel points and X-ray energy. The relationships between the image pixel points, voltage, and current were quantified, and the resultant correlations were observed to obey some physical laws.

A new method is proposed to determine the binding energy ($B$) of near proton-drip line isotopes from isotopic cross section distribution. To determine $B$ of $Z~=$ 22-28 isotopes (with $T_{z}=-$2 and $-$5/2), the lack of cross sections for proton-rich isotopes in the 345$A$ MeV $^{78}$Kr + $^9$Be is overcome by predicting the proton-rich isotopes from a newly discovered scaling phenomenon found in the proton-rich isotopes measured in the 140$A$ MeV $^{40,~48}$Ca($^{58,~64}$Ni) + $^9$Be reactions. The cross sections for proton-rich isotopes are verified to exponentially depend on the average binding energy per nucleon, based on which $B$ of the $Z~$=22-28 isotopes with $T_{z}=~-$2 and $-$5/2 are determined from cross sections. The determined $B$ of the isotopes are justified from obeying the scaling phenomenon of the difference between the mass of mirror nuclei. The cross sections for the $Z~=$ 22-28 isotopes with $T_{z}=~-$1 and $-$3/2, which in potential can be experimentally studied in mass storage ring, are also predicted.

The production of $\ensuremath{\alpha}$-particle decaying heavy nuclei in reactions of 7.5--6.1 MeV/nucleon $^{238}\mathrm{U}$ +$^{232}\mathrm{Th}$ was explored using an in-beam detection array composed of YAP scintillators and gas ionization chamber-Si telescopes. Comparisons of $\ensuremath{\alpha}$ energies and half-lives for the observed products with those of the previously known isotopes and with theoretically predicted values indicate the observation of a number of previously unreported $\ensuremath{\alpha}$ emitters. $\ensuremath{\alpha}$-particle decay energies reaching as high as 12 MeV are observed. Many of these are expected to be from decay of previously unseen relatively neutron rich products. While the contributions of isomeric states require further exploration and specific isotope identifications need to be made, the production of heavy isotopes with quite high atomic numbers is suggested by the data.

Because the properties of the QCD phase transition and the chiral magnetic effect (CME) depend on the number of quark flavors ($N_{f}$) and quark mass, relativistic heavy-ion collisions provide a natural environment to investigate the flavor features if quark deconfinement occurs. We introduce an initial two-flavor or three-flavor dipole charge separation into a multiphase transport (AMPT) model to investigate the flavor dependence of the CME. By taking advantage of the recent ALICE data of charge azimuthal correlations with identified hadrons, we attempt to disentangle two-flavor and three-flavor CME scenarios in Pb+Pb collisions at 2.76 TeV. We find that the experimental data show a certain potential to distinguish the two scenarios, therefore we further suggest to collect more data to clarify the possible flavor dependence in future experiments., 12 pages, 4 figures; final published version

The Shannon information entropy theory is used to explain the recently proposed isobaric yield ratio difference (IBD) probe which aims to determine the nuclear symmetry energy. Theoretically, the difference between the Shannon uncertainties carried by isobars in two different reactions (Delta In-21), is found to be equivalent to the difference between the chemical potentials of protons and neutrons of the reactions [the IBD probe, IB-Delta (beta mu)(21), with beta the reverse temperature]. From the viewpoints of Shannon information entropy, the physical meaning of the above chemical potential difference is interpreted by Delta In-21 as denoting the nuclear symmetry energy or density difference between neutrons and protons in reactions more concisely than from the statistical ablation-abrasion model. (C) 2015 The Authors. Published by Elsevier B.V.

The deformation evolution of giant dipole resonance (GDR), in the chains of Sm and Nd isotopes, are investigated in the framework of an extended quantum molecular dynamics (EQMD) model. The mass number dependence of resonance peak position (Em) in the major and minor axis directions of deformed nuclei as well as the difference Delta E-m between them are described in detail. The correlation between the splitting (Delta E-m/(E) over bar (m)) of the GDR spectra and the deformation (beta(2)) is further studied. The results confirm that Delta Em/(E) over barE(m) is proportional to beta(2). By comparing the calculation with the experimental data on photon absorption cross section sigma(gamma), it shows that the EQMD model can quite well reproduce the shape of GDR spectra from spherical to prolate shape. The GDR shapes in Sm-134, Sm-136, Sm-138, Nd-130, Nd-132, and Nd-134 are also predicted. In addition, the symmetry energy coefficient (E-sym) dependence of GDR spectra of Nd-150 is also discussed. It is found that the calculated GDR spectrum in the EQMD model is perfectly consistent with the experimental results when Esym equals 32 MeV.

The drift of the isospin degree of freedom (IDOF) is experimentally visualized through the wide-range angular distribution and the beam energy dependence of the isospin composition of light charged particles (LCP) produced in heavy ion collisions. It is evidenced that the net isospin transport is presented in the whole process from early dynamic emission to the statistical evaporation lasting to very late stage. Due to the long-time accumulation of the isospin effect, the angular distribution of the relative neutron excess summing over the LCPs is utilized as a sensitive probe to the symmetry energy. With S fixed at 28.3 MeV, a soft density dependence with L=33–61 MeV (0.95 confidential level) at ρ0 is circumstantially deduced using an improved quantum molecular dynamics transport model attached with a statistical emission afterburner.

The Bayesian neural network (BNN) method is proposed to predict the isotopic cross-sections in proton induced spallation reactions. Learning from more than 4000 data sets of isotopic cross-sections from 19 experimental measurements and 5 theoretical predictions with the SPACS parametrization, in which the mass of the spallation system ranges from 36 to 238, and the incident energy from 200 MeV/u to 1500 MeV/u, it is demonstrated that the BNN method can provide good predictions of the residue fragment cross-sections in spallation reactions.

The isoscaling and the isobaric yield ratio difference (IBD) probes, which both are constructed by yield ratio of fragment, provide cancelation of parameters. The information entropy theory is introduced to explain the physical meaning of the isoscaling and IBD probes. The similarity between the isoscaling and IBD results is found, i.e., the information uncertainty determined by the IBD method equals to $\beta-\alpha$ determined by the isoscaling [$\alpha$ ($\beta$) is the parameter fitted from the isotopic (isotonic) yield ratio]., Comment: accepted by Communications in Theoretical Physics

Background: The isobaric ratio difference scaling phenomenon, which has been found for the fragments produced in projectile fragmentation reactions, is related to the nuclear density change in reaction systems.Purpose: To verify whether the isobaric ratio difference scaling exists in the fragments produced in the spallation and fission reactions.Methods: The isobaric ratio difference scaling, denoted by ${S}_{\mathrm{\ensuremath{\Delta}}ln{R}_{21}}$, is in theory deduced within the framework of the canonical ensemble theory at the grand-canonical limitation. The fragments measured in a series of projectile fragmentation, spallation, and fission reactions have been analyzed.Results: A good ${S}_{\mathrm{\ensuremath{\Delta}}ln{R}_{21}}$ scaling phenomenon is shown for the fragments produced both in the projectile fragmentation reactions and in the spallation reactions, whereas the ${S}_{\mathrm{\ensuremath{\Delta}}ln{R}_{21}}$ scaling phenomenon for the fragments in the fission reaction is less obvious.Conclusions: The ${S}_{\mathrm{\ensuremath{\Delta}}ln{R}_{21}}$ scaling is used to probe the properties of the equilibrium system at the time of fragment formation. The good scaling of ${S}_{\mathrm{\ensuremath{\Delta}}ln{R}_{21}}$ suggests that the equilibrium state can be achieved in the projectile fragmentation and spallation reactions. Whereas in the fission reaction, the result of ${S}_{\mathrm{\ensuremath{\Delta}}ln{R}_{21}}$ indicates that the equilibrium of the system is hard to achieve.

The pairing energy (${E}_{p}$) of fragments, which is assumed to have a finite temperature in heavy-ion collisions, is obtained using an isobaric yield ratio method in the framework of a modified Fisher model. The fragments in the measured and simulated $140A$ MeV $^{40,48}\mathrm{Ca}+\phantom{\rule{0.16em}{0ex}}^{9}\mathrm{Be}/^{181}\mathrm{Ta}$ and $^{58,64}\mathrm{Ni}+\phantom{\rule{0.16em}{0ex}}^{9}\mathrm{Be}/^{181}\mathrm{Ta}$ reactions have been adopted to perform the analysis. The results show that the ratio of the pairing-energy coefficient to the temperature (${a}_{p}/T$) is not significantly influenced by the reaction system, but depends on the neutron excess $(I=N\ensuremath{-}Z)$ of the fragment. For most fragments, ${a}_{p}/T$ falls in the range of $\ensuremath{-}1.0l{a}_{p}/Tl1.0$. Assuming $T\ensuremath{\approx}2.0$ MeV for the intermediate-mass fragments, ${a}_{p}\ensuremath{\sim}2.0$ MeV is suggested, which is much smaller than the value in the semiclassical mass formula. For a neutron-rich fragment, ${E}_{p}$ may disappear. The results are confirmed by the calculated ${E}_{p}$ of some $A=34$ isobars using the self-consistent finite-temperature relativistic Hartree-Bogoliubov model with the effective interaction PC-PK1 and the Gogny-pairing interaction D1S. The calculated ${E}_{p}$ depends on $T$ in the form of $y=Cexp(\ensuremath{-}a{T}^{4})$ and ${E}_{p}$ goes to zero fast with temperatures at around $T=0.8$ MeV. The results are useful for improving the secondary decay simulation for primary fragments in the heavy-ion collisions.

We have calculated the cross sections of the fragments produced in the projectile fragmentation of the even 36–52 Ca isotopes using the statistical abrasion-ablation model. The isospin effect in the projectile fragmentation are studied by investigating the peak positions and the widths of the fragment isotopic cross section distributions. The peak positions of the fragments isotopic cross section distributions have good linear correlation to the Z of the fragments and the correlations are fitted using the linear function. The correlations between slopes b and the binding energies of the neutron ( S n) of the projectile nuclei, the differences between the binding energies of the neutron and proton( S n- S p) of the projectile nuclei and the neutron-skin thickness (δnp) are studied. It is found that b and δnp has a good linear correlation for the neutron-rich projectile nuclei.

The ratio of pairing-energy coefficient to temperature ($a_{p}/T$) of neutron-rich fragments produced in spallation reactions has been investigated by adopting an isobaric yield ratio method deduced in the framework of a modified Fisher model. A series of spallation reactions, 0.5$A$ and 1$A$ GeV $^{208}$Pb + $p$, 1$A$ GeV $^{238}$U + $p$, 0.5$A$ GeV $^{136}$Xe + $d$, 0.2$A$, 0.5$A$ and 1$A$ GeV $^{136}$Xe + $p$, and $^{56}$Fe + $p$ with incident energy ranging from 0.3$A$ to 1.5$A$ GeV, has been analysed. An obvious odd-even staggering is shown in the fragments with small neutron excess ($I\equiv N - Z$), and in the relatively small-$A$ fragments which have large $I$. The values of $a_{p}/T$ for the fragments, with $I$ from 0 to 36, have been found to be in a range from -4 to 4, and most values of $a_{p}/T$ fall in the range from -1 to 1. It is suggested that a small pairing-energy coefficient should be considered in predicting the cross sections of fragments in spallation reactions. It is also concluded that the method proposed in this article is not good for fragments with $A/A_{s} >$ 85\% (where $A_{s}$ is the mass number of the spallation system)., 8 pages, 6 figures, to appear on Chinese Physics C

\item[Background] Temperature is an important parameter in studying many important questions in heavy-ion collisions. A thermometer based on the isobaric yield ratio (IYR) has been proposed [Ma \textit{et al.}, Phys. Rev. C \textbf{86}, 054611 (2012) and Ma \textit{et al.}, \textit{ibid.}, Phys. Rev. C \textbf{88}, 014609 (2013)]. \item[Purpose] An improved thermometer ($T_{IB}$) is proposed based on the difference between IYRs. $T_{IB}$ obtained from isobars in different reactions will be compared. \item[Methods] The yields of three isobars are employed in $T_{IB}$. The residual free energy of the three isobars are replaced by that of the binding energy. No secondary decay modification for odd $A$ fragment is used in $T_{IB}$. \item[Results] The measured fragment yields in the 140$A$ MeV $^{40, 48}$Ca + $^{9}$Be ($^{181}$Ta) and $^{58, 64}$Ni + $^9$Be ($^{181}$Ta), the 1$A$ GeV $^{124, 136}$Xe + Pb, and the $^{112,124}$Sn + $^{112,124}$Sn reactions have been analyzed to obtain $T_{IB}$ from IMFs. $T_{IB}$ from most of the fragments in the $^{40, 48}$Ca and $^{58, 64}$Ni reactions is in the range of 0.6 MeV $ < T_{IB} < $ 3.5 MeV. $T_{IB}$ from most of the fragments in the $^{124}$Xe and $^{112,124}$Sn reactions is in the range of 0.5 MeV $ < T_{IB} < $ 2.5 MeV, while the range is 0.5 MeV $ < T_{IB}, Comment: 7 pages, 9 figures. To appear on Physical Review C

`The isobaric yield ratio difference between two reactions is found to equal Delta mu(21)/ T, which denotes the ratio of the difference between the neutron and proton chemical potentials to the temperature. A series of projectile fragmentation reactions induced by calcium isotopes are calculated using a modified statistical abrasion-ablation model, assuming the neutron density distribution to be the Fermi type. The Delta mu(21)/ T from the prefragments are found to be sensitive to the difference between the neutron density distributions of projectiles, while Delta mu(21)/ T from the final fragments are very similar for the reactions and insensitive to the difference between the neutron density distributions of projectiles. The Delta mu(21)/ T from the prefragments and final fragments verify that the deexcitation modifies the results largely.

The cross sections of fragments produced of the six pairs of | T Z | = 2 mirror nuclei projectile fragmentation were calculated using the statistical abrasion-ablation model. The isospin dependence of the projectile fragmentation are studied by investigating the fragments isotopic cross section distributions. It is found that the isospin dependence of the fragments production are related to the difference between the neutron and proton density distributions in the nuclei.

The residue Coulomb interaction (RCI), which affects the results of symmetry energy of neutron-rich nucleus in isobaric yield ratio (IYR) methods, is difficult to be determined. Four RCI approximations are investigated: (1) the M1--RCI adopting the $a_{c}/T$ (the ratio of Coulomb energy coefficient to temperature) determined from the IYR of mirror-nuclei fragment; (2) the M2--RCI by fitting the difference between IYRs; (3) the M3--RCI by adopting the standard Coulomb energy at a temperature $T=2$MeV; and (4) neglecting the RCI among the three isobars. The M1--, M2-- and M3--RCI is found to no larger than 0.4. In particular, the M2--RCI is very close to zero. The effects of RCI in the $a_{sym}/T$ of fragment are also studied. The M1-- and M4--$a_{sym}/T$ are found to be the lower and upper limitations of $a_{sym}/T$, respectively. The M2--$a_{sym}/T$ overlaps the M4--$a_{sym}/T$, which indicates that the M2--RCI is negligible, at the same time the RCI among the three isobars can be neglected. A relative consistent low values of M3--$a_{sym}/T$ ($7.5\pm2.5$) are found in very neutron-rich isobars., Comment: 7pages, 7 figures

The isobaric yield ratio difference (IBD) between two reactions of similar experimental setups is found to be sensitive to nuclear density differences between projectiles. In this article, the IBD probe is used to study the density variation in neutron-rich $^{48}$Ca. By adjusting diffuseness in the neutron density distribution, three different neutron density distributions of $^{48}$Ca are obtained. The yields of fragments in the 80$A$ MeV $^{40, 48}$Ca + $^{12}$C reactions are calculated by using a modified statistical abrasion-ablation model. It is found that the IBD results obtained from the prefragments are sensitive to the density distribution of the projectile, while the IBD results from the final fragments are less sensitive to the density distribution of the projectile., Comment: 3 figures

The isoscaling and isobaric ratio difference (IBD) methods are used to study the $\Delta\mu/T$ ($\Delta\mu$ being the difference between the chemical potentials of neutron and proton, and $T$ being the temperature) in the measured 1$A$ GeV $^{124}$Sn + $^{124}$Sn, $^{112}$Sn + $^{112}$Sn, $^{136}$Xe + Pb and $^{124}$Xe + Pb reactions. The isoscaling phenomena in the $^{124}$Sn/$^{112}$Sn and the $^{136}$Xe/$^{124}$Xe reactions pairs are investigated, and the isoscaling parameter $\alpha$ and $\beta$ are obtained. The $\Delta\mu/T$ determined by the isoscaling method (IS--$\Delta\mu/T$) and IBD method (IB--$\Delta\mu/T$) in the measured Sn and Xe reactions are compared. It is shown that in most of fragments, the IS-- and IB-- $\Delta\mu/T$ are consistent in the Xe reactions, while the IS-- and IB-- $\Delta\mu/T$ are only similar in the less neutron-rich fragments in the Sn reactions. The shell effects in IB--$\Delta\mu/T$ are also discussed., Comment: 5 figures, submitted to J. Phys. G: Nucl. Part. Phys

\item[Purpose] We suppose that the IYR(m) depends on the neutron-skin thickness ($\delta_{np}$) of the projectile, and check the idea of whether the neutron-skin thickness effects can fully explain the systematic dependence of the IYR(m). \item[Methods] A modified statistical abrasion-ablation model is used to calculate the reactions induced by projectiles of three series. \item[Results] The IYR(m) shows a distribution of a linear part in the small-$x$ fragments, and a nonlinear part in the large-$x$ fragments. The linear part of IYR(m) is fitted. (1) In the calcium isotopic reactions, the IYR(m) depends on the isospin or the volume of the projectile, but $\delta_{np}$ greatly influences the nonlinear part of the IYR(m). The IYR(m) does not depend on the colliding source in reactions of small $b_{\mbox{max}}$ for the nonneutron-rich projectiles, and does not depend on the collision sources in reactions by the neutron-rich projectiles; (2) In reactions of the $A = 45$ isobars, though IYR(m) depends on the isospin of projectile, IYR(m) shows small dependence on isospin if $\delta_{np} > 0$; (3) In the reactions of projectiles having similar $\delta_{np}$, the IYR(m) in the small mass fragments show no dependence on the volume and the isospin of the projectile when the mass of the projectile is relatively large. Specially, the dependence of IYR(m) on the mass of the isospin of the projectile vanishes when $\delta_{np}\sim0.02$fm. \item[Conclusions] The linear and nonlinear parts of the IYR(m) are governed by the core and the surface (skin) of the projectile, respectively. The neutron-skin effects can well explain the systematic dependence of the IYR(m)., Comment: 9 figures, to appear in Physical Review C

Background: The temperature in heavy-ion collisions is an important question because it reflects the violence of the collisions and affects the results of many important parameters in nuclear physics.Purpose: In this work, we focus on the investigation of the temperature of the measured fragments in the 1A GeV Sn-112,Sn-124 + Sn-112,Sn-124, and Xe-124,Xe-36 + Pb reactions.Methods: The isobaric yield ratio method is deduced in a grand-canonical theory. The decay contribution and the pairing energy contribution to the free energy of the fragment are considered in the analysis.Results: For the odd I (I N - Z) fragment the decay or pairing energy contribution is found unnecessary. For the even I fragments, both the decay contribution and the decay plus pairing energy contribution can weaken the staggering in the isobaric yield ratios. For the odd I fragment, the temperature in this work is consistent with that of the modified Fisher model [Phys. Rev. C 86, 054611 (2012)]. For the even I fragment, the temperature at which the decay plus the pairing energy contribution have been taken in account is consistent with that of the the odd I fragments. The isospin dependence of the temperature determined by the isobaric yield ratio method is also found.Conclusions: In the grand-canonical theory, after the correction of the decay plus pairing energy to the free energy of the fragments, reasonable temperature of the even I fragment can be obtained.

Using the isospin-dependent quantum molecular dynamics (IQMD) model, the sensitivity of isospin ratios from projectile and target fragmentation towards the density-dependent symmetry energy for the neutron-rich reaction systems Ca-40,Ca-48+ Ni-58,Ni-64 at 50 and 600 MeV/nucleon has been studied. The kinetic energy spectra of neutron-to-proton single and double ratios are elaborated in detail. The neutron-to-proton double ratio in neutron-rich projectile fragmentation is provided as a useful tool for the density dependence of symmetry energy near the subsaturation density. The sensitivity of the kinetic energy spectra of isospin ratios towards the isospin effect or symmetry energy reduces at suprasaturation density because of secondary nucleon-nucleon collisions.

An isobaric yield ratio difference (IBD) method is proposed to study the ratio of the difference between the chemical potential of neutron and proton to temperature ($\Delta\mu/T$) in heavy-ion collisions. The $\Delta\mu/T$ determined by the IBD method (IB-$\Delta\mu/T$) is compared to the results of the isoscaling method (IS-$\Delta\mu/T$), which uses the isotopic or the isotonic yield ratio. Similar distributions of the IB- and IS-$\Delta\mu/T$ are found in the measured 140$A$ MeV $^{40,48}$Ca + $^{9}$Be and the $^{58,64}$Ni + $^{9}$Be reactions. The IB- and IS-$\Delta\mu/T$ both have a distribution with a plateau in the small mass fragments plus an increasing part in the fragments of relatively larger mass. The IB- and IS-$\Delta\mu/T$ plateaus show dependence on the $n/p$ ratio of the projectile. It is suggested that the height of the plateau is decided by the difference between the neutron density ($\rho_n$) and the proton density ($\rho_p$) distributions of the projectiles, and the width shows the overlapping volume of the projectiles in which $\rho_n$ and $\rho_p$ change very little. The difference between the IB- and IS-$\Delta\mu/T$ is explained by the isoscaling parameters being constrained by the many isotopes and isotones, while the IBD method only uses the yields of two isobars. It is suggested that the IB-$\Delta\mu/T$ is more reasonable than the IS-$\Delta\mu/T$, especially when the isotopic or isotonic ratio disobeys the isoscaling. As to the question whether the $\Delta\mu/T$ depends on the density or the temperature, the density dependence is preferred since the low density can result in low temperature in the peripheral reactions., Comment: 6 pages, 6 figures, mistake of reference corrected

This work focuses on the study of temperature associated with the final heavy fragments in reactions induced by both the neutron-proton symmetric and the neutron-rich projectiles, and with incident energy ranges from 60$A$ MeV to 1$A$ GeV. Isobaric yield ratio (IYR) is used to determine the temperature of heavy fragments. Cross sections of measured fragment in reactions are analyzed, and a modified statistical abrasion-ablation (SAA) model is used to calculate the yield of fragment in 140$A$ MeV $^{64}$Ni + $^{9}$Be and 1$A$ GeV $^{136}$Xe + $^{208}$Pb reactions. Relatively low $T$ of heavy fragments are obtained in different reactions ($T$ ranges from 1 to 3MeV). $T$ is also found to depend on the neutron-richness of the projectile. The incident energy affects $T$ very little. $\Delta\mu/T$ (the ratio of the difference between the chemical potential of neutron and proton to temperature) is found to increase linearly as $N/Z$ of projectile increases. It is found that $T$ of the $^{48}$Ca reaction, for which IYRs are of $A, Comment: 7 pages, 6 figures

In the framework of a modified Fisher model, the ratio of the symmetry-energy coefficient to temperature (a sym /T) is extracted from the fragment produced in the 124, 136Xe induced reactions using the isobaric yield ratio methods based on different approximations. It is found that for nuclei with the same neutron excess (I ≡ N − Z) increases when the mass of the fragment increases, while for isobar a sym /T decreases when I increases. It is also found that the extracted a sym /T of the nucleus has very little dependence on the n/p ratio of the projectile, target, and the incident energies in the reaction.

The neutron removal cross section [${\ensuremath{\sigma}}_{\ensuremath{-}N}(Z)$] is defined for the projectile-like fragment isotopes and extended to the lower $Z$ isotopes in the projectile fragmentation reaction. The cross sections of fragments in 1 $A$ GeV even $^{42\ensuremath{-}52}\mathrm{Ca}$$+$$^{12}\mathrm{C}$ projectile fragmentation reactions are calculated using the statistical abrasion-ablation model. The correlations between ${\ensuremath{\sigma}}_{\ensuremath{-}N}(Z)$ of different fragment isotopes and neutron skin thickness ($S$${}_{n}$) for finite neutron-rich nuclei are revisited. Good linear ${\ensuremath{\sigma}}_{\ensuremath{-}N}(Z)\ensuremath{-}{S}_{n}$ correlations are observed in fragment isotopes, and it is suggested that ${\ensuremath{\sigma}}_{\ensuremath{-}N}(Z)$ be used as an observable to determine $S$${}_{n}$ of neutron-rich nucleus in addition to ${\ensuremath{\sigma}}_{\ensuremath{-}N}$ for isotopes of the projectile nucleus.

Shannon information-entropy uncertainty is used to analyze fragments in the measured 140A MeV Ca + 9Be and Ni + 9Be reactions. A scaling phenomenon is found in the information-uncertainty difference of fragments between the reactions. The scaling phenomenon is explained in the manner of canonical ensemble theory, and is reproduced in simulated reactions using the antisymmetric molecular dynamics (AMD) and AMD + GEMINI models. The probes based on information uncertainty, requiring no equilibrium state of reaction, can be used in the non-equilibrium system, and bridge the results of the static thermodynamics models and the evolving dynamical transport models.

The cross sections of fragments produced in the 140 A MeV58,64Ni+9 Be projectile fragmentation reactions are calculated by using the antisymmetrized molecular dynamics (AMD) model, the modified statistical abrasion-ablation (SAA) model, and the empirical EPAX2/EPAX3 formulae. The Gogny-g0 interaction is taken as the effective nucleon-nucleon interaction in the AMD calculation, and the decays of fragments obtained from the AMD results are calculated by using the GEMINI code. The calculated cross sections of fragments are compared.

The neutron induced reactions on 23Na are investigated by using the Talys1.4 program. The calculated results for the 23Na(n, 2n)22Na reaction are found to agree with the experimental results. The cross sections of the residues of the (n, n), (n, γ), (n, p), and (n, np) channels in the reactions are presented, and at the same time, the neutron induced reactions on 22Ne are also investigated.