This paper investigates the impact of differential rotation on the bulk properties and onset of rotational instabilities in neutron stars at finite temperatures up to 50 MeV.
Utilizing the relativistic Brueckner-Hartree-Fock (RBHF) formalism in full Dirac space, the study constructs equation of state (EOS) models for hot neutron star matter, including conditions relevant for high temperatures. These finite-temperature EOS models are applied to compute the bulk properties of differentially rotating neutron stars with varying structural deformations.
The findings demonstrate that the stability of these stars against bar-mode deformation, a key rotational instability, is only weakly dependent on temperature. Differential rotation significantly affects the maximum mass and radius of neutron stars, and the threshold for the onset of bar-mode instability shows minimal sensitivity to temperature changes within the examined range.
These findings are crucial for interpreting observational data from neutron star mergers and other high-energy astrophysical events. The research underscores the necessity of incorporating differential rotation and finite temperature effects in neutron star models to predict their properties and stability accurately.
The Shanghai high repetition rate XFEL and extreme light facility (SHINE) accelerates electrons up to 8 GeV using cryogenic-superconducting high-frequency cavity. Wire scanner system is applied to the beam profile measurement of SHINE due to its advantages such as fewer secondary particles generation compared with that of complete beam block, hence reduce the risk of superconducting cavity.
This study aims to design data acquisition system for wire scanner system and realize synchronous acquisition of beam loss signal and relative position between the wire and beam.
The data acquisition system for wire scanner was designed to include radio frequency (RF) daughter board with analog signal digitizer, digital motherboard, firmware, data processing software. A Zynq-UltraScale+ based system on chip (SoC) was employed as system central component, and a field programmable gate array (FPGA) was used for system control and data transmission whilst the advanced RISC machine (ARM) integrating Linux was implemented for data acquisition and communication. Finally, experimental test of this data acquisition system was performed on the testbed to verify its feasibility and functionalities.
The data acquisition system can correctly read back position of grating ruler, and achieve synchronous acquisition of sample beam loss signal and signal of cavity beam position monitor.
The data acquisition system meets the requirements of SHINE wire scanner system. It will be applied to the prototype of SHINE wire scanner system.
Digital bunch-by-bunch feedback control is the best way to control bunch instability. It will be applied to the super collider to suppress the beam oscillation within a dozen or even several cycles. The damping time of circular electron positron collider (CEPC) and FCC-ee ( Future Circle Collider e-e+ ) is very short, but it is impossible to realize through using traditional digital feedback system.
This study aims to cure the coupled-bunch instability by using a dual-feedback control system to reduce the damping time for BEPCII (Beijing Electron Positron Collider II).
Several feedback systems operate simultaneously and act on the same time beam in storage ring can superimpose the damping effect and then reduce the damping time of the system. With the favorable condition of two stripline kicker located on the outer ring, we make a experimental research about double feedback system in BEPCII synchrotron mode. Among the double feedback system, one system is the self-make digital bunch-by-bunch transverse feedback system based commercial card, the other system is the commercial feedback system produced by the Dimtel company.
The damping time of commercial feedback system is measured as 0.93 ms, the damping time of self-make digital bunch-by-bunch transverse feedback system based commercial card is measured as 2.98 ms, and the damping time of double feedback system is measured as 0.70 ms.
Several feedback systems work simultaneously can effectively reduce the damping time turn by turn.
The space environment contains numerous high-energy particles, and a single high-energy particle passing through a spacecraft shell bombards the electronic devices within, triggering single-particle effects such as device logic state upset and function failures, which, in turn, affect spacecraft operation reliability and mission accomplishment.
Notably, ground accelerator irradiation tests provide an important and effective means for simulating space single event effects and for predicting the risks of single event effect rates for electronic devices in space applications. Generally, electronic devices can be used in spacecraft only if their resistance radiation indicators meet astronautical application requirements.
Spacecraft are typically exposed to space radiation particles, primarily heavy ions and protons; therefore, single event effect simulation testing for electronic devices relies predominantly on heavy ion and proton accelerators. To address the requirements of single event effect testing, technologies such as large-area beam expansion and homogenization, high-precision beam current diagnosis, and efficient test terminals have been developed to fulfill the requirements of various test tasks.
Particular focus is placed on the CIAE's (China Institute of Atomic Energy) heavy ion single event and proton single event effect simulation test techniques and the heavy ion microbeam technique for radiation sensitive area identification for electronic devices. Subsequently, the aforementioned techniques are applied to a single event effect risk evaluation for astronautical electronic devices.
In the future, the demand for radiation-resistant devices is expected to continue to increase in the aerospace, nuclear industry, and other radiation application fields. It is, therefore, necessary to further exploit the irradiation potential of existing domestic single event effect simulation equipment and establish new accelerator platforms with improved capacity for single event effect simulation testing.
The expected signal rate of rare decay experiments, such as instance dark matter and neutrino less double beta decay experiments, is extremely low, which requires that the detector building materials have extremely low radioactivity. Low radioactive background control is one of the essential works in the rare decay experiments. 226Ra and 228Ra produced in the early decay chain of 238U and 232Th have low boiling point and high vapor pressure, removing the element Ra can break the 238U decay chain and keep a low radioactivity of 232Th-late for a long time.
This study aims to investigate vacuum melting technique for low background titanium to reduce the impurity of isotopes that have negative impact on rare decay experiments and creating a low background environment for the detector running.
Firstly, the low background material samples were acquired by manual separation of radionuclides using physical and chemical methods. Then, radioactive impurity elements, such as K, Cs, Ra, Pb, Po and Rn with low boiling point and high vapor pressure, were volatilized in environment with high temperature and high vacuum level. Finally, radioactivity of these testing samples were measured by two sets of high-purity germanium γ spectrometer with measurement time extended to 7 days.
Measurement results show signs of removal of radioactive isotopes by smelting-vacuum method, and the impurity in pure titanium smelted in vacuum electron beam furnace can reach the levels of (0.13±0.69) mBq∙kg-1 for 232Th-228Ac, and (0.07±0.29) mBq∙kg-1 for 238U-222Rn, respectively.
The smelting-vacuum method could provide reliable low background material for the container of the next generation PandaX detector.
Neutrons play an important role in nuclear detection applications, and make up for the shortcomings of X-ray detection insensitivity to the atomic number. In a specific energy range, the cross section of neutron reaction varies drastically with the neutron energy, and resonance occurs. The resonance spectrum of nuclides is unique, and qualitative and quantitative analysis of nuclides can be carried out based on this. Among them, the resonance energy range of medium-heavy nuclei is in the eV~keV energy range, which is an important part of neutron resonance analysis.
Due to the lack of conclusive articles on neutron resonance in medium-heavy nuclei, this paper summarizes the current research on neutron resonance.
By querying a large number of journal papers and books related to neutron resonance, the theory and application of neutron resonance of medium and heavy nuclear are summarized.
At present, there have been many research results, and they have been widely used in temperature measurement, imaging, non-destructive analysis, nuclear data measurement, and other aspects. In this regard, by reviewing the literature and books on neutron resonance, the research status of neutron resonance at domestic and overseas are summarized and analyzed, and its development tendency is forecast.
The Shashlik electromagnetic calorimeter (ECAL) is used in the Nuclotron-based Ion Collider Facility's MultiPurpose detector (NICA-MPD) of the Russian heavy ion superconducting synchrotron. It is designed as a cylindrical barrel divided into 32 sectors with a total of 43 008 towers. Each tower is composed of 220 layers of lead and 221 layers of scintillator alternately.
This study aims to simulate multiple parameters of Shashlik ECAL for NICA-MPD that affect the performance of ECAL.
First of all, the module of ECAL tower was built based on the principle of Shashlik ECAL. Then, the GEENT4 software was employed to simulate the performance of every single tower of ECAL according to its structure composition. Considering the influence of the design parameters of the scintillator and absorber on energy deposition, energy resolution, and energy leakage after electrons were incident on the tower and the subsequent scintillator luminescence process, the influence of the reflective layer on the number of photons was in the wavelength shifted fiber and detector. Finally, factors that affected energy deposition, energy leakage, energy resolution, and photon number in the wavelength shift (WLS) and sensor, and the influence of the thickness, number of layers, and size of the scintillator and absorber in the module on energy deposition, energy leakage, and energy resolution were simulated and analyzed.
The simulation results show that the best side length of cross-section of each tower is 4 cm. When the total thickness of absorber and scintillator is 1.8 mm and the thickness of lead absorber is 0.3 mm, the energy resolution meets the experimental requirements of 5%@3 GeV. When the radiation length reaches 13
The photon numbers in the wavelength shift fiber and the detector are affected by the reflection layer on both the tower side and the end face of the fiber. The importance and necessity of adding reflector are verified by this study.
The large high altitude air shower observatory (LHAASO) is a major national science and technology infrastructure approved for the 12th Five-Year Plan. It is one of the scientific infrastructures with the highest altitude in China and its core goal is to explore high-energy cosmic ray. As an important component of LHAASO, the ground shower particle array (KM2A) has a huge total area of one square kilometer. Unlike most high-energy physics experiments, the KM2A has a total of about 6 500 channels, and a total input bandwidth of about 546 MB∙s-1. There is no hardware trigger function in KM2A.
This study aims to design and implement a software for KM2A to complete the trigger and real-time data processing.
Data transmission scheme based on standard Ethernet and TCP / IP protocol was employed to receive all packet data including all detector units at the same time. Online processing and calculation of data packets were achieved by using the configured trigger algorithm. Data with physical significance were extracted and packaged to form different events with physical labels, then these events were sent to different receivers according to the configured output rules. By using distributed technology and task division, this software was able to finish real-time data processing through selectable algorithm scheduling.
The software is able to trigger KM2A in real time, reduce the amount of data, and lessen the burden of transmission and storage. It has been put into use in the data center of 4 410 m altitude experiment site, and has been running well so far.