Part I: Explaining the “Muon g - 2” Results with Probabilistic Spacetime

A recent experimental finding replicated an earlier research result, both of which demonstrated conflict with a specific Standard Model prediction. The “Muon g - 2” studies have indicated that the degree of muon precession predicted by the Model is not the same as observed. The researchers offer many posteriori atheoretical hypotheses as possible explanations of their findings, but no fundamental theoretical understanding of the near discovery is among them. This article describes both an explication for the unexpected result and describes its underlying mechanism based on an existing cosmological theory, the Probabilistic Spacetime Theory. The paper also discusses the potential value of this theory.

The Role of Atmospheric Pressure, Temperature, and Humidity on Cosmic Ray Muons at a Low Latitude Station

This study aimed to investigate the relationship between atmospheric conditions and cosmic ray (CR) muons using daily and monthly CR data collected by the KAAU muon detector in Jeddah, Saudi Arabia between 2007 and 2012. Specifically, the study examined the effects of atmospheric pressure, air temperature, and relative humidity on CR muons at different time scales (annual, seasonal, and monthly). The results of the analysis revealed that atmospheric pressure and air temperature had a negative impact on CR muons, while relative humidity had a positive impact. Although air temperature and relative humidity had small mean values across all time scales, their coefficients varied significantly from month to month and season to season. In addition, the study conducted multivariable correlation analyses for each day, which showed that pressure coefficients had consistently negative mean values, while the temperature and humidity coefficients had varying effects, ranging from positive to negative values. The reasons for the variations in the coefficients are not yet fully understood, but the study proposed several possible terrestrial and extraterrestrial explanations. These findings provide important insights into the complex interactions between the Earth’s atmosphere and cosmic rays, which can contribute to a better understanding of the potential impacts of cosmic rays on the Earth’s climate and environment.

BESⅢ MUON气体监测器数据获取系统

为系统研究BESⅢ MUON气体监测器在55Fe 5.9keV X射线辐照时的性能,基于CAMAC总线技术以LabVIEW搭建并编译坪曲线数据获取系统和全能光电峰幅度谱数据获取系统。为减少运行时测试系统电子学开支,优化系统,基于研华PCI-1716L采集卡搭建了数据采集系统,结合LabVIEW和ROOT编译了性能稳定、数据分析精确的取数软件。

BESⅢMuon鉴别器电子学系统的VME控制/扇出插件的设计和测试

本文介绍了BESIII Muon鉴别器读出电子学系统的VME控制/扇出插件的设计,其中包括插件的功能和结构,插件上FPGA逻辑的设计等。插件在制作和调试完成后,进行了相关功能和稳定性的测试。

BESⅢ Muon鉴别器前端电子学读出系统

本文介绍了BESⅢ Muon前端电子学读出系统的结构,详细说明了依据菊花链方式的前端板和基于USB的读出板的设计和实现方法。该系统中较多地采用了FPGA技术,极大地降低了系统的复杂程度和建造成本。文章最后介绍了系统的自检方式,并给出了该系统在北京高能物理研究所谱仪大厅内的宇宙线测试结果,论证了系统的可靠性。

BESⅢ MUON气体监测器的研制与安装测试

研制计数管监测器,通过监测55Fe 5.9keV X射线光电峰,实时监测BESⅢMUON探测器的气体配比。经过系列实验研究了计数管的各种性能,明确其工作模式为有限正比模式;选取最佳工作高压保证监测器可以长期稳定运行。基于LabVIEW和ROOT编译了集成的PCI数据获取系统,实时在线显示监测结果。根据电子学信号特点,合理安装监测器高压、气体、电子学,减小测试系统开支。完成安装调试后进行长时间监测,并报告了初步的测试结果。

BESⅢMUON探测器建造和质量控制数据库

介绍了BESIII Muon探测器在建造过程中的质量控制数据库。基于MySQL+PHP+A- pache组合开发的数据库可以实现Muon探测器从单元制造测试到整体安装检验的全程资料和数据的即时更新、查询与显示等功能。此数据库尝试将数据库和网络的优点应用到探测器建造过程的质量跟踪与控制环节,不仅有利于质量的保证和效率的提高,而且为探测器的维护提供透明的技术支持平台。

Classical Dynamics of Muonic-Electronic Helium and Heliumlike Ions: The Allowance for the Eccentricity of the Muon and Nucleus Orbits

In the previous paper by one of us (hereafter paper I), the author considered Rydberg states of the muonic-electronic helium atom or helium-like ion and used the fact that the muon motion occurs much more rapidly than the electron motion. Assuming that the muon and nucleus orbits are circular, he applied the analytical method based on separating rapid and slow subsystems. He showed that the electron moves in an effective potential that is mathematically equivalent to the potential of a satellite orbiting an oblate planet like the Earth. He also showed that the “unperturbed” elliptical orbit of the electron engages in two precessions simultaneously: the precession of the electron orbit in the plane of the orbit and the precession of the orbital plane of the electron around the axis perpendicular to the plane of the muon and nuclear orbits. The problem remained whether or not the allowance for the ellipticity of the orbit could significantly change the results. In the present paper, we address this problem: we study how the allowance for a relatively low eccentricity ε of the muon and nucleus orbits affects the motion of the electron. We derive an additional, ε-dependent term in the effective potential for the motion of the electron. We show analytically that in the particular case of the planar geometry (where the electron orbit is in the plane of the muon and nucleus orbits), it leads to an additional contribution to the frequency of the precession of the electron orbit. We demonstrate that this additional, ε-depen- dent contribution to the precession frequency of the electron orbit can reach the same order of magnitude as the primary, ε-independent contribution to the precession frequency. Therefore, the results of our paper seem to be important not only qualitatively, but also quantitatively.

羊八井Muon望远镜中基于FPGA的方向测量电路

方向测量电路在羊八井Muon望远镜中用于测定Muon粒子的入射方向。该望远镜由上下相隔一定距离两层6×4排列的塑料闪烁体探测器阵列构成,能探测77个Muon粒子的入射方向及各个方向入射粒子计数率。能监测记录到高计数率、窄脉宽的输入信号以及极短的死时间是Muon望远镜对方向探测电路的要求。借助资源丰富、高速的FPGA,在单个芯片上实现了Muon望远镜方向探测电路所要求的全部功能。此外由于FPGA提供在线编程,使得对系统的功能修改或升级非常方便。低功耗是基于FPGA的方向测量电路的另一大优势。

Simulation and Design of Tentative Muon Source Based on CSNS

This paper presents a conceptual design for the first tentative surface muon source based on the proton beam provided by China Spallation Neutron Source （CSNS）. We have calcu- lated the optimal parameters of solid muon target, in which the method of Monte Carlo simula- tion is used to obtain the optimal muon beam parameters, such as beam fiuence rate, momentum spread and phase space distribution. A simple muon transport beamline system was also designed, which could transport the muons emitted from the muon target into the experimental area, where positrons from muon decay in a test sample are detected by a spectrometer. The beam optics of this new beam line is also described.

Imaging internal density structure of the Laoheishan volcanic cone with cosmic ray muon radiography

Muon radiography is a promising technique for imaging the internal density structures of targets such as tunnels,pyramids,and volcanoes up to a scale of a few hundred meters by measuring the flux attenuation of cosmic ray muons after they have traveled through these targets.In this study,we conducted experimental muon radiography of one of the volcanoes in the Wudalianchi area in Northeast China to image its internal density structure.The muon detector used in this study was composed of plastic scintillators and silicon photomultipliers.After approximately one and a half months of observing the crater and conduit of the Laoheishan volcano cone in Wudalianchi from September 23^(rd) to November 10^(th) 2019,more than 3 million muon tracks fulfilling the data selection criteria were collected.Based on the muon samples and high-resolution topography obtained through aerial photogrammetry using an unmanned aerial vehicle,a density image of the Laoheishan volcano cone was constructed.The results obtained in this experiment demonstrate the feasibility of using a radiography technique based on plastic scintillator detectors.To obtain the density distribution,we performed a detailed background analysis and found that low-energy charged particles dominated the background noise.Relatively higher densities were found near the surface of the volcanic cone,whereas relatively lower densities were found near the center of the volcanic cone.The experiment in this study is the first volcano muon tomography study performed in China.Our work provides an important reference for future research.

Reconstruction of a muon bundle in the JUNO central detector

The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment.One of the main goals is to determine the neutrino mass ordering by precisely measuring the energy spectrum of reactor antineutrinos.For the detection of reactor antineutrinos,cosmogenic backgrounds,such as^(9)Li/^(8)He and fast neutrons induced by cosmic muons,should be rejected carefully by applying muon veto cuts,which require good muon track reconstruction.With a 20-kton liquid scintillator detector,the simulation shows the proportion of muon bundles(muon multiplicity≥2)to be approximately 8%in JUNO,whereas its reconstruction has been rarely discussed in previous experiments.This study proposes an efficient algorithm for muon track reconstruction based on the charge response of a photomultiplier tube array.This is the first reconstruction of muon bundles in a large-volume liquid scintillator detector.In addition,the algorithm shows good performance and potential for reconstruction for both a single muon and double muons(muon multiplicity=2).The spatial resolution of a single-muon reconstruction was20 cm,and the angular resolution was 0.5°.For doublemuon reconstruction,the spatial and angular resolutions could be 30 cm and 1.0°,respectively.Moreover,this paper also discusses muon classification and the veto strategy.

A muon high-resolution pseudorange measurement method: Application to muon navigation in confined spaces

Confined spaces such as polar regions, deep earth and deep ocean are crucial navigation scenarios where traditional navigation techniques have difficulty in obtaining external signals for positioning. The cosmic ray muons, which carry the spatial and energetic information, are easy to penetrate these confined spaces. Therefore, the unique muon characteristic provides a new perspective to estimate detector position, which can be considered using in confined spaces navigation.In this paper, a well-developed theory of muon navigation is established by combining a muon pseudorange measurement method. Moreover, an Equivalent Velocity Calculation Model(EVCM)and a Muon Sequence Matching Technology(MSMT) are proposed. The first model corrects flight pseudorange error caused by the relativistic energy loss and the second technology compensates the random error in pseudorange measurement. Further, a series of simulations are performed to analyze the muon events number which can be received by detector in different scenarios with the variations of zenith angle, detector area, varied detector plates gap, and muon flight distance.Meanwhile, the simulation results demonstrate that the muon navigation update rate every 10 minutes can reach 5.989 in confined spaces at 100 m, and further pseudorange error analysis indicates that the meter-level positioning accuracy can be acquired. Finally, we construct a muon coincidence measurement scheme and verify that the laws of the muon positioning system for high-energy muons are consistent with the simulation results.

BESⅢ Muon电子学VME控制扇出插件的优化设计

主要阐述BESⅢ Muon电子学VME控制扇出插件的优化设计,主要内容包括对VME控制扇出插件控制芯片FPGA的固件进行优化,并且设计了相关实验来对优化方案进行测试。

BESⅢ Muon前端电子学数据链过流保护系统设计

论文介绍了BESⅢ Muon前端电子学数据链过流保护系统的设计,其主要功能是监控数据链供电,防止数据链受大电流损伤。文章主要阐述了过流保护系统的软硬件设计,同时给出了过流保护系统原型机各项基本指标的测试结果。

A modified multi-group model of angular and momentum distribution of cosmic ray muons for thickness measurement and material discrimination of slabs

Muon tomography is a capable imaging technique to measure the geometry of high-Z objects. However,most existed algorithms used in muon tomography have obscured the effects of angular distribution and momentum spectra of cosmic ray muons and reduced the spatial resolution. We present a modified multi-group model that takes into account these effects and calibrates the model by the material of lead. Performance tests establish that the model is capable of measuring the thickness of a Pb slab and identifying the material of an unknown slab on a reasonable exposure timescale, in both cases of complete and incomplete angular data. Results show that the modified multi-group model is helpful for improvements in image resolution in real applications.

Experimental validation of material discrimination ability of muon scattering tomography at the TUMUTY facility

Muon scattering tomography is believed to be a promising technique for cargo container inspection, owing to the ability of natural muons to penetrate into dense materials and the absence of artificial radiation. In this work, the material discrimination ability of muon scattering tomography is evaluated based on experiments at the Tsinghua University cosmic ray muon tomography facility,with four materials: flour(as drugs substitute), aluminum,steel, and lead. The features of the different materials could be discriminated with cluster analysis and classifiers based on support vector machine. The overall discrimination precisions for these four materials could reach 70, 95, and 99% with 1-, 5-, and 10-min-long measurement,respectively.

A segmented conical electric lens for optimization of the beam spot of the low-energy muon facility at PSI: a Geant4 simulation analysis

The low-energy muon facility at PSI provides nearly fully polarized positive muons with tunable energies in the ke V range to carry out muon spin rotation(LE-μSR)experiments with nanometer depth resolution on thin films,heterostructures, and near-surface regions. The low-energy muon beam is focused and transported to the sample by electrostatic lenses. In order to achieve a minimum beam spot size at the sample position and to enable the steering of the beam in the horizontal and vertical direction, a special electrostatic device has been implemented close to the sample position. It consists of a cylinder at ground potential followed by four conically shaped electrodes,which can be operated at different electric potential. In LE-μSR experiments, an electric field at the sample along the beam direction can be applied to accelerate/decelerate muons to different energies(0.5–30 keV). Additionally, a horizontal or vertical magnetic field can be superimposed for transverse or longitudinal field μSR experiments. The focusing properties of the conical lens in the presence of these additional electric and magnetic fields have been investigated and optimized by Geant4 simulations. Some experimental tests were also performed and show that the simulation well describes the experimental setup.

A possible scheme for the surface muon beamline at CSNS

An experimental muon source is planned for the China Spallation Neutron Source.A simplified beamline with a limited number of magnets is achieved using a FODO lattice for implementation in a future preliminary stage.The yield of the muon delivered to the experimental sample is slightly larger than 10^5 μ^+/s within the FWHM beam spot(-φ30 mm)from a thick muon target.In addition,the beam polarization is 92%and the contamination that is mainly formed by positrons is approximately a fraction of 1%.

Hybrid model for muon tomography and quantitative analysis of image quality

Muon tomography is a novel method for the non-destructive imaging of materials based on muon rays,which are highly penetrating in natural background radiation.Currently,the most commonly used imaging methods include muon radiography and muon tomography.A previously studied method known as coinciding muon trajectory density tomography,which utilizes muonic secondary particles,is proposed to image low and medium atomic number(Z)materials.However,scattering tomography is mostly used to image high-Z materials,and coinciding muon trajectory density tomography exhibits a hollow phenomenon in the imaging results owing to the self-absorption effect.To address the shortcomings of the individual imaging methods,hybrid model tomography combining scattering tomography and coinciding muon trajectory density tomography is proposed and verified.In addition,the peak signal-to-noise ratio was introduced to quantitatively analyze the image quality.Different imaging models were simulated using the Geant4 toolkit to confirm the advantages of this innovative method.The simulation results showed that hybrid model tomography can image centimeter-scale materials with low,medium,and high Z simultaneously.For high-Z materials with similar atomic numbers,this method can clearly distinguish those with apparent differences in density.According to the peak signal-to-noise ratio of the analysis,the reconstructed image quality of the new method was significantly higher than that of the individual imaging methods.This study provides a reliable approach to the compatibility of scattering tomography and coinciding muon trajectory density tomography.