Vol.35,

Jin-Cheng Wang，Jie Ren，Wei Jiang，Xi-Chao Ruan，Ying-Yi Liu，Hao-Lan Yang，Kuo-Zhi Xu，Xin-Yi Pan，Qi Sun，Jie Bao，Han-Xiong Huang，Hao-Fan Bai，Jiang-Bo Bai，Ping Cao，Qi-Ping Chen，Yong-Hao Chen，Wen-Hao Duan，An-Chuan Fan，Rui-Rui Fan，Chang-Qing Feng，Min-Hao Gu，Chang-Cai Han，Zi-Jie Han，Guo-Zhu He，Yong-Cheng He，Yang Hong，Yi-Wei Hu，Zhi-Jie Jiang，Ling Kang，Chang-Lin Lan，Bo Li，Feng Li，Qiang Li，Xiao Li，Yang Li，Jie Liu，Rong Liu，Shu-Bin Liu，Yi-Na Liu，Guang-Yuan Luan，Chang-Jun Ning，Yi-Jia Qiu，Wen-Kai Ren，Zhi-Zhou Ren，Zhao-Hui Song，Kang Sun，Zhi-Xin Tan，Jing-Yu Tang，Sheng-Da Tang，Li-Jiao Wang，Peng-Cheng Wang，Zhao-Hui Wang，Zhong-Wei Wen，Xiao-Guang Wu，Xuan Wu，Ze-Peng Wu，Cong Xia，Li-Kun Xie，Han Yi，Tao Yu，Yong-Ji Yu，Guo-Hui Zhang，Hang-Chang Zhang，Qi-Wei Zhang，Xian-Peng Zhang，Yu-Liang Zhang，Zhi-Yong Zhang，Mao-Yuan Zhao，Zhi-Hao Zhou，Ke-Jun Zhu，Chong Zou

The back-streaming white-neutron beam line (Back-n) of the China Spallation Neutron Source is an essential neutron-research platform built for the study of nuclear data, neutron physics, and neutron applications. Many types of cross-sectional neutron-reaction measurements have been performed at Back-n since early 2018. These measurements have shown that a significant number of gamma rays can be transmitted to the experimental stations of Back-n along with the neutron beam. These gamma rays, commonly referred to as in-beam gamma rays, can induce a non-negligible experimental background in neutron-reaction measurements. Studying the characteristics of in-beam gamma rays is important for understanding the experimental background. However, measuring in-beam gamma rays is challenging because most gamma-ray detectors are sensitive to neutrons; thus, discriminating between neutron-induced signals and those from in-beam gamma rays is difficult. In this study, we propose the use of the black resonance filter method and a CeBr₃ scintillation detector to measure the characteristics of the in-beam gamma rays of Back-n. Four types of black resonance filters, ¹⁸¹Ta, ⁵⁹Co, ^natAg, and ^natCd, were used in this measurement. The time-of-flight (TOF) technique was used to select the detector signals remaining in the absorption region of the TOF spectra, which were mainly induced by in-beam gamma rays. The energy distribution and flux of the in-beam gamma rays of Back-n were determined by analyzing the deposited energy spectra of the CeBr₃ scintillation detector and using Monte Carlo simulations. Based on the results of this study, the background contributions from in-beam gamma rays in neutron-reaction measurements at Back-n can be reasonably evaluated, which is beneficial for enhancing both the experimental methodology and data analysis.

269

Understanding the properties of nuclei near the double magic nucleus ⁴⁰Ca is crucial for both nuclear theory and experiments. In this study, Ca isotopes were investigated using an extended pairing-plus-quadrupole model with monopole corrections. The negative-parity states of ⁴⁴Ca were coupled with the intruder orbital g_9/2 at 4 MeV. The values of E₄₊/E₂₊ agree well with experimental trend from ⁴²Ca to ⁵⁰Ca, considering monopole effects between νf_7/2 and νp_3/2 (νf_5/2). This monopole effect, determined from data of ⁴⁸Ca and ⁵⁰Ca, supports the proposed new nuclear magic number N = 34 by predicting a high-energy 2⁺ state in ⁵⁴Ca.

229

We investigated the properties of the phase diagram of high-order susceptibilities, speed of sound, and polytropic index based on an extended Nambu-Jona-Lasinio model with an eight-quark scalar-vector interaction. Non-monotonic behavior was observed in all these quantities around the phase transition boundary, which also revealed the properties of the critical point. Further, this study indicated that the chiral phase transition boundary and critical point could vary depending on the scalar-vector coupling constant G_SV. At finite densities and temperatures, the negative G_SV term exhibited attractive interactions, which enhanced the critical point temperature and reduced the chemical potential. The G_SV term also affected the properties of the high-order susceptibilities, speed of sound, and polytropic index near the critical point. The nonmonotonic (peak or dip) structures of these quantities shifted to a low baryon chemical potential (and high temperature) with a negative G_SV. G_SV also changed the amplitude and range of the nonmonotonic regions. Therefore, the scalar-vector interaction was useful for locating the phase boundary and critical point in QCD phase diagram by comparing the experimental data. The study of the non-monotonic behavior of high-order susceptibilities, speed of sound, and polytropic index is of great interest, and further observations related to high-order susceptibilities, speed of sound, and polytropic index being found and applied to the search for critical points in heavy-ion collisions and the study of compact stars are eagerly awaited.

256

Multinucleon transfer in low-energy heavy-ion collisions is increasingly considered a promising approach for generating exotic nuclei. Understanding the complex mechanisms involved in multinucleon transfer processes presents significant challenges for the theoretical investigation of nuclear reactions. A Langevin equation model was developed and employed to investigate multinucleon transfer processes. The ⁴⁰Ar + ²³²Th reaction was simulated, and the calculated Wilczyński plot was used to verify the model. Additionally, to study the dynamics of multinucleon transfer reactions, the ¹³⁶Xe + ²³⁸U and ¹³⁶Xe + ²⁰⁹Bi reactions were simulated, and the corresponding TKE-mass and angular distributions were computed to analyze the energy dissipation and scattering angles. This investigation enhances our understanding of the dynamics involved in multinucleon transfer processes.

226

Precise knowledge of the nuclear symmetry energy can be tentatively calibrated using multimessenger constraints. The neutron skin thickness of a heavy nucleus is one of the most sensitive indicators for probing the isovector components of effective interactions in asymmetric nuclear matter. Recent studies have suggested that the experimental data from the CREX and PREX2 collaborations are not mutually compatible with existing nuclear models. In this study, we review the quantification of the slope parameter of the symmetry energy L from the neutron skin thicknesses of ⁴⁸Ca and ²⁰⁸Pb. Skyrme energy density functionals classified by various isoscalar incompressibility coefficients K were employed to evaluate the bulk properties of finite nuclei. The calculated results suggest that the slope parameter L deduced from ²⁰⁸Pb is sensitive to the compression modulus of symmetric nuclear matter, but not that from ⁴⁸Ca. The effective parameter sets classified by K=220 MeV can provide an almost overlapping range of L from ⁴⁸Ca and ²⁰⁸Pb.

207

The covariant density functional theory (CDFT) and five-dimensional collective Hamiltonian (5DCH) are used to analyze the experimental deformation parameters and moments of inertia (MoIs) of 12 triaxial nuclei as extracted by Allmond and Wood [J. M. Allmond and J. L. Wood, Phys. Lett. B 767, 226 (2017)]. We find that the CDFT MoIs are generally smaller than the experimental values but exhibit qualitative consistency with the irrotational flow and experimental data for the relative MoIs, indicating that the intermediate axis exhibites the largest MoI. Additionally, it is found that the pairing interaction collapse could result in nuclei behaving as a rigid-body flow, as exhibited in the ^186-192Os case. Furthermore, by incorporating enhanced CDFT MoIs (factor of f≈1.55) into the 5DCH, the experimental low-lying energy spectra and deformation parameters are reproduced successfully. Compared with both CDFT and the triaxial rotor model (TRM), the 5DCH demonstrates superior agreement with the experimental deformation parameters and low-lying energy spectra, respectively, emphasizing the importance of considering shape fluctuations.

213

Interest has recently emerged in potential applications of (n, 2n) reactions of unstable nuclei. Challenges have arisen because of the scarcity of experimental cross-sectional data. This study aims to predict the (n, 2n) reaction cross-section of long-lived fission products based on a tensor model. This tensor model is an extension of the collaborative filtering algorithm used for nuclear data. It is based on tensor decomposition and completion to predict (n, 2n) reaction cross-sections; the corresponding EXFOR data are applied as training data. The reliability of the proposed tensor model was validated by comparing the calculations with data from EXFOR and different databases. Predictions were made for long-lived fission products such as ⁶⁰Co, ⁷⁹Se, ⁹³Zr, ¹⁰⁷Pd, ¹²⁶Sn, and ¹³⁷Cs, which provide a predicted energy range to effectively transmute long-lived fission products into shorter-lived or less radioactive isotopes. This method could be a powerful tool for completing (n, 2n) reaction cross-sectional data and shows the possibility of selective transmutation of nuclear waste.

199

The neutron radiation field has vital applications in areas such as biomedicine, geology, radiation safety, and many others for neutron detection and neutron metrology. Correcting neutron fluence rate perturbation accurately is an important yet challenging problem. This study proposes a correction method that analyzes three physical processes. This method, which transforms the detection process from point detection to area detection, is based on a novel physical model and has been validated through theoretical analyses, experiments, and simulations. According to the average differences between the calculated and experimental results, the new method (1.67%)demonstrated better accuracy than the traditional simulation (2.17%). In a closed thermal neutron radiation field, the detector or strong neutron absorption material significantly perturbs the neutron fluence rate, whereas its impact on the energy spectrum shape and neutron directionality is relatively minor. Furthermore, based on the calculation results of the perturbation rate formula for medium materials with different compositions and sizes, the larger the volume and capture cross-section of the medium, the higher the perturbation rate generated in the closed radiation field.

174

The newly developed software, Nucleus++, is an advanced tool for displaying basic nuclear physics properties from Nubase and integrating comprehensive mass information for each nuclide from Atomic Mass Evaluation. Additionally, it allows users to compare experimental nuclear masses with predictions from different mass models. Building on the success and learning experiences of its predecessor, Nucleus, this enhanced tool introduces improved functionality and compatibility. With its user-friendly interface, Nucleus++ was designed as a valuable tool for scholars and practitioners in the field of nuclear science. This article offers an in-depth description of Nucleus++, highlighting its main features and anticipated impacts on nuclear science research.

249

Synchrotron microscopic data commonly suffer from poor image quality with degraded resolution incurred by instrumentation defects or experimental conditions. Image restoration methods are often applied to recover the reduced resolution, providing improved image details that can greatly facilitate scientific discovery. Among these methods, deconvolution techniques are straightforward, yet either require known prior information or struggle to tackle large experimental data. Deep learning (DL)-based super-resolution (SR) methods handle large data well, however data scarcity and model generalizability are problematic. In addition, current image restoration methods are mostly offline and inefficient for many beamlines where high data volumes and data complexity issues are encountered. To overcome these limitations, an online image-restoration pipeline that adaptably selects suitable algorithms and models from a method repertoire is promising. In this study, using both deconvolution and pretrained DL-based SR models, we show that different restoration efficacies can be achieved on different types of synchrotron experimental data. We describe the necessity, feasibility, and significance of constructing such an image-restoration pipeline for future synchrotron experiments.

209

In addition to the tens of millions of medical doses consumed annually around the world, a vast number of nuclear magnetic resonance imaging (MRI) contrast agents are being deployed in MRI research and development, offering precise diagnostic information, targeting capabilities, and analyte sensing. Superparamagnetic iron oxide nanoparticles (SPIONs) are notable among these agents, providing effective and versatile MRI applications while also being heavy-metal-free, bioconjugatable, and theranostic. We designed and implemented a novel two-pronged computational and experimental strategy to meet the demand for the efficient and rigorous development of SPION-based MRI agents. Our MATLAB-based modeling simulation and magnetic characterization revealed that extremely small maghemite SPIONs in the 1–3 nm range possess significantly reduced transversal relaxation rates (R₂) and are therefore preferred for positive (T₁-weighted) MRI. Moreover, X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) analyses demonstrated that the diffraction pattern and radial distribution function of our SPIONs matched those of the targeted maghemite crystals. In addition, simulations of the X-ray near-edge structure (XANES) spectra indicated that our synthesized SPIONs, even at 1 nm, maintained a spherical structure. Furthermore, in vitro and in vivo MRI investigations showed that our 1-nm SPIONs effectively highlighted whole-body blood vessels and major organs in mice and could be cleared through the kidney route to minimize potential post-imaging side effects. Overall, our innovative approach enabled a swift discovery of the desired SPION structure, followed by targeted synthesis, synchrotron radiation spectroscopic studies, and MRI evaluations. The efficient and rigorous development of our high-performance SPIONs can set the stage for a computational and experimental platform for the development of future MRI agents.

206

This study investigates the effects of displacement damage on the dark signal of a pinned photodiode CMOS image sensor (CIS) following irradiation with back-streaming white neutrons from white neutron sources at the China Spallation Neutron Source (CSNS) and Xi’an Pulsed Reactor (XAPR). The mean dark signal, dark signal non-uniformity (DSNU), dark signal distribution, and hot pixels of the CIS were compared between the CSNS back-n and XAPR neutron irradiations. The non-ionizing energy loss and energy distribution of primary knock-on atoms in silicon, induced by neutrons, were calculated using the open-source package Geant4. An analysis combining experimental and simulation results showed a noticeable proportionality between the increase in the mean dark signal and the displacement damage dose (DDD). Additionally, neutron energies influence DSNU, dark signal distribution, and hot pixels. High neutron energies at the same DDD level may lead to pronounced dark signal non-uniformity and elevated hot pixel values.

267

Owing to the Thomson scattering between relativistic electrons and a laser, continuously polarization-tunable X-rays can be easily generated, providing an excellent probe for advanced X-ray imaging. In this paper, a method for simultaneous fluorescence and Compton scattering computed tomography is proposed using linearly polarized X-rays. The proposed method feasibility was verified using Monte Carlo simulations. In the simulations, the phantom is a polytetrafluoroethylene (Teflon) cylinder inside which are cylindrical columns containing aluminum, water, and gold (Au)-loaded water solutions with Au concentrations ranging between 0.5–4.0 wt%, and a parallel hole collimator imaging geometry was adopted. By adjusting the incident X-ray polarization direction, both the X-ray fluorescence computed tomography (XFCT) and Compton scattering computed tomography (CSCT) images of the phantom were accurately reconstructed using a maximum-likelihood expectation maximization algorithm. A similar attenuation contrast problem for the different cylindrical columns in the phantom can be resolved in the XFCT and CSCT images. The interplay between XFCT and CSCT was analyzed and the contrast-to-noise ratio (CNR) of the reconstruction was improved by correcting for the mutual influence between the two imaging modalities. Compared with K-edge subtraction imaging, XFCT exhibits a CNR advantage for the phantom.

211

Ultrahigh-dose rate radiotherapy (FLASH-RT) is a revolutionary radiotherapy technology that can spare normal tissues without compromising tumor control. Although qualitative experimental results have been reported, quantitative and systematic analysis of data is necessary. Particularly, the FLASH effect response model to the dose or dose rate is still unclear. This study investigated the relationships between the FLASH effect and experimental parameters, such as dose, dose rate, and other factors by analyzing published in vivo experimental data from animal models. The data were modeled based on logistic regression analysis using the sigmoid function. The model was evaluated using prediction accuracy, receiver operating characteristic (ROC) curve, and area under the ROC curve. Results showed that the FLASH effect was closely related to the dose, mean dose rate, tissue type, and corresponding biological endpoints. The dose rate corresponding to a 50% probability of triggering cognitive protection in the brain was 45 Gy s^-1. The dose rate corresponding to a 50% probability of triggering intestinal crypt survival and regeneration was 140 Gy s^-1. For the skin toxicity effect, the dose corresponding to a 50% probability of triggering the FLASH effect was 24 Gy. This study helps to characterize the conditions underlying the FLASH effect and provides important information for optimizing experiments.

205

The application of superconducting (SC) technology enables magnets to excite strong fields with small footprints, which has great potential for miniaturizing proton therapy gantries. However, the slow ramping rate of SC magnets results in a low treatment efficiency compared with normal-conducting (NC) gantries. To address this problem, this study proposes a compact proton therapy gantry design with a large momentum acceptance utilizing alternating-gradient canted-cosine-theta (AG-CCT) SC magnets. In our design, a high-transmission degrader is mounted in the middle of the gantry, and the upstream beamline employs NC magnets with small apertures. Downstream of the degrader, large-bore AG-CCT magnets with strong alternating focusing gradients are set symmetrically as a local achromat, which realizes a momentum acceptance of 20% (or 40% in the energy domain). Therefore, only three magnetic working points are required to cover a treatment energy of 70–230 MeV. Owing to the large momentum acceptance, the proton beam after the degrader can be directly delivered to the isocenter without truncating its energy spectrum, which can significantly increase the treatment efficiency but causes severe dispersion effects during pencil beam scanning. Therefore, a compensation method was introduced by tuning the normal and skewed quadrupoles during the scanning process. As a result, the new gantry not only presents a remarkable reduction in the size and weight of the facility but also shows good potential for fast treatment.

219

The impact of the radiation dose produced by ²²²Rn/²²⁰Rn and its progeny on human health has garnered increasing interest in the nuclear research field. The establishment of robust, regulatory, and competent ²²⁰Rn chambers is crucial for accurately measuring radioactivity levels. However, studying the uniformity of the ²²⁰Rn progeny through experimental methods is challenging, because measuring the concentration of ²²⁰Rn and its progeny in multiple spatial locations simultaneously and in real time using experimental methods is difficult. Therefore, achieving precise control of the concentration of ²²⁰Rn and its progeny as well as the reliable sampling of the progeny pose significant challenges. To solve this problem, this study uses computational fluid dynamics to obtain the flow-field data of the ²²⁰Rn chamber under different wind speeds and progeny-replenishment rates. Qualitative analysis of the concentration distribution of the progeny and quantitative analysis of the progeny concentration and uniformity of the progeny concentration are conducted. The research findings indicated that the progeny-concentration level is primarily influenced by wind speed and the progeny-complement rate. Wind speed also plays a crucial role in determining progeny-concentration uniformity, whereas the progeny-complement rate has minimal impact on uniformity. To ensure the accuracy of ²²⁰Rn progeny-concentration sampling, we propose a methodology for selecting an appropriate sampling area based on varying progeny concentrations. This study holds immense importance for enhancing the regulation and measurement standards of ²²⁰Rn and its progeny.

221

The helical undulator is in high demand in synchrotron radiation facilities for circular polarization generation. Owing to the higher field strength provided by the superconducting undulator compared to the conventional permanent-magnet undulator, greater research efforts should be directed towards this area. The helical superconducting undulator holds great potential in synchrotron radiation facilities, especially in low-energy storage rings that seek circularly polarized radiation with the highest possible radiation flux. Following the successful development of planar superconducting undulators, the Institute of High Energy Physics conducted research and development for the helical superconducting undulator. A 0.5-m-long Delta-type superconducting undulator prototype was developed and tested. Detailed information on the design, fabrication, and cryogenic testing of the prototype are presented and discussed.

183

A compact 10 MeV S-band irradiation electron linear accelerator (linac) was developed to simulate electronic radiation in outer space and perform electron irradiation effect tests on spacecraft materials and devices. According to the requirements of space environment simulation, the electron beam energy can be adjusted in the range from 3.5 MeV to 10 MeV, and the average current can be adjusted in the range from 0.1 mA to 1 mA. The linac should be capable of providing beam irradiation over a large area of 1 m² with a uniformity greater than 90% and a scanning rate of 100 Hz. A novel method was applied to achieve such a high beam scanning rate by combining a kicker and a scanning magnet. Based on this requirement, a design for the 10 MeV linac is proposed with an RF power pulse repetition rate of 500 Hz; it includes a thermal cathode electron gun, a bunching-accelerating section, and a scanning transport line. The detailed physical design and dynamic simulation results of the proposed 10 MeV electron linac are presented in this paper.

209

This study investigates the coupling response of cables inside a metal cavity under X-ray irradiation using the finite-difference time-domain method, particle-simulation method, and transmission-line equation to solve the electromagnetic field inside the cavity and load voltage at the cable terminal under X-ray excitation. The results show that under a strong ionizing radiation environment of 1 J/cm², a strong electromagnetic environment is generated inside the cavity. The cable-shielding layer terminal couples a voltage of 15.32 V, whereas the core wire terminal couples a voltage of 0.31 V. Under strong X-ray irradiation, the metal cavity not only fails to provide electromagnetic shielding, but also introduces new electromagnetic interference. This study also provides a method for reducing the number of emitted electrons by adding low-Z materials, which can effectively reduce the coupled electric field and voltage.

189

Tritium, a radioactive nuclide discharged by nuclear power plants, poses challenges for removal. Continuous online monitoring of tritium in water is crucial for real-time radiation data, given its predominant existence in the environment as water. This paper presents the design, simulation, and development of a tritium monitoring device utilizing a plastic scintillation fiber (PSF) array. Experimental validation confirmed the device’s detection efficiency and minimum detectable activity. The recorded detection efficiency of the device is 1.6×10^-3, which exceeds the theoretically simulated value of 4×10^-4 by four times. Without shielding, the device can achieve a minimum detectable activity of 3165 BqL^-1 over a 1600-second measurement duration. According to simulation and experimental results, enhancing detection efficiency is possible by increasing the number and length of PSFs and implementing rigorous shielding measures. Additionally, reducing the diameter of PSFs can also improve detection efficiency. The minimum detectable activity of the device can be further reduced using the aforementioned methods.

228

To improve the heat transfer efficiency of the coolant in lead-based fast reactors, this study optimized the configuration and rotational direction of the spacer wires in fuel assemblies to design a new-pattern fuel assembly. This study conducted detailed comparisons between traditional and new pattern fuel assembly rod bundles utilizing the open-source computational fluid dynamics platform, OpenFOAM. The results indicated that the new design may significantly reduce the pressure drop along the rod bundle, which is beneficial for lowering the pressure drop. Furthermore, this new design improved coolant mixing in the subchannels, which facilitated a more uniform temperature distribution and lower thermal gradients at the assembly outlet. These factors collectively reduced the thermal fatigue and creep in nearby internal components. Overall, the new-pattern fuel assembly proposed in this study may have better heat transfer performance, thereby enhancing the Integrated Thermal-Hydraulic Factor by 48.2% compared to the traditional pattern.

177

The cooling storage ring (CSR) external-target experiment (CEE) is a spectrometer used in construction to study the properties of nuclear matter in high-baryon density regions at the Heavy-Ion Research Facility in Lanzhou (HIRFL). This study presents the design, simulation, manufacturing, and testing of a half-size prototype of a multi-wire drift chamber (MWDC) for the CEE. First, the performance of the MWDC connected to home-made electronics was simulated. The results demonstrated that an energy resolution of 18.5% for 5.9-keV X-rays and a position resolution of 194 μm for protons can be achieved by the current design. Because the size of the largest MWDC reached 176 cm × 314 cm, a set of 98 cm × 98 cm prototypes was built using the new techniques. The positioning accuracy of the anode wires in this prototype is better than 20 μm. After optimization, using commercially available electronics, the prototype can achieved an energy resolution of 19.7% for a ⁵⁵Fe X-ray source. The CEE-MWDC detector and electronics were simultaneously tested. An energy resolution of 22% was achieved for the ⁵⁵Fe source; the track residuals were approximately 330 μm for the cosmic rays. The results demonstrate that the current design and techniques meet the requirements of the CEE-MWDC array.

241

In energy-dispersive X-ray fluorescence spectroscopy, the estimation of the pulse amplitude determines the accuracy of the spectrum measurement. The error generated by the amplitude estimation of the pulse output distorted by the measurement system leads to false peaks in the measured spectrum. To eliminate these false peaks and achieve an accurate estimation of the distorted pulse amplitude, a composite neural network model is proposed, which embeds long and short-term memory (LSTM) into the UNet structure. The UNet network realizes the fusion of pulse sequence features and the LSTM model realizes pulse amplitude estimation. The model is trained using simulated pulse datasets with different amplitudes and distortion times. For the pulse height estimation, the average relative error of the trained model on the test set was approximately 0.64%, which is 27.37% lower than that of the traditional trapezoidal shaping algorithm. Offline processing of a standard iron source further validated the pulse height estimation performance of the UNet-LSTM model. After estimating the amplitude of the distorted pulses using the model, the false-peak area was reduced by approximately 91% over the full spectrum and was corrected to the characteristic peak region of interest (ROI). The corrected peak area accounted for approximately 1.32% of the characteristic peak ROI area. The results indicate that the model can accurately estimate the height of distorted pulses and has substantial corrective effects on false peaks.

160

In theoretical investigations of ³⁶Ar published by Ge Ren et. al in Physics Letters B, 138990(2024), ³⁶Ar bubble nuclei, characterized by central density depletions, were studied using the extended quantum molecular dynamics model. Three novel density distributions—micro-bubble, bubble, and cluster resonances—were identified, each showing distinct spectral signatures in the gamma-ray decay spectrum of the isoscalar monopole resonance. Notably, the oscillation frequency of the bubble mode mirrors macroscopic bubble dynamics, bridging classical and quantum phenomena in atomic nuclei.

189