Study of primordial deuterium abundance in Big Bang nucleosynthesis

Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)He,^(4)He,and^(7) Li produced in the early universe.Among these,deuterium,the first nuclide produced by BBN,is a key primordial material for subsequent reactions.To date,the uncertainty in predicted deuterium abundance(D/H)remains larger than the observational precision.In this study,the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium abundance.We found that the reaction rate uncertainties of the four reactions d(d,n)^(3)He,d(d,p)t,d(p,γ)^(3)He,and p(n,γ)d had the largest influence on the calculated D/H uncertainty.Currently,the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^(3) He rate.From the nuclear physics aspect,there is still room to largely reduce the reaction-rate uncertainties;hence,further measurements of the important reactions involved in BBN are still necessary.A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ)d.

The large-scale modular BGO detection array(LAMBDA)design and test

Total absorption gamma-ray spectroscopy(TAGS)is a powerful tool for measuring complexγ transitions,which has been effectively applied to the study of reactor decay heat.This paper presents the design of a new TAGS detector,the large-scale modular BGO detection array(LAMBDA),tailored for measuringβ-decay intensity distributions of fission products.The modular design allows the LAMBDA detectors to be assembled in various configurations.The final version of LAMBDA consists of 102 identical 60 mm×60 mm×120 mm BGO crystals and exhibits a high full-energy peak efficiency exceeding 80%at 0.5∼8 MeV based on a Monte Carlo simulation.Currently,approximately half of the LAMBDA modules have been manufactured.Tests usingγ-ray sources and nuclear reactions demonstrated favorable energy resolution,energy linearity,and efficiency uniformity across the modules.Forty-eight modules have been integrated into the prototype LAMBDA-I.The capability of LAMBDA-I inβ-delayedγ-decay experiments was evaluated by commissioning measurements using the ^(152)Eu source.

Measurements ofthe 197Au(n, γ) crosssectionupto100keV at the CSNSBack-nfacility

The neutron capture cross section of 197 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 c-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 1eV to 1 keV were fitted by the SAMMY R-matrix code.

Measurements of the ^(107)Ag neutron capture cross sections with pulse height weighting technique at the CSNS Back-n facility

Silver indium cadmium(Ag–In–Cd) control rod is widely used in pressurized water reactor nuclear power plants,and it is continuously consumed in a high neutron flux environment. The mass ratio of ^(107)Ag in the Ag–In–Cd control rod is 41.44%. To accurately calculate the consumption value of the control rod, a reliable neutron reaction cross section of the ^(107)Ag is required. Meanwhile,^(107)Ag is also an important weak r nucleus. Thus, the cross sections for neutron induced interactions with ^(107)Ag are very important both in nuclear energy and nuclear astrophysics. The(n, γ) cross section of ^(107)Ag has been measured in the energy range of 1–60 eV using a back streaming white neutron beam line at China spallation neutron source. The resonance parameters are extracted by an R-matrix code. All the cross section of ^(107)Ag and resonance parameters are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00010.

Primary yields of protons measured using CR-39 in laser-induceddeuteron–deuteron fusion reactions

Investigating deuteron–deuteron(DD)fusion reactions in a plasma environment similar to the early stages of the Big Bang is an important topic in nuclear astrophysics.In this study,we experimentally investigated such reactions,using eight laser beams with the third harmonic impacting on a deuterated polyethylene target at the ShenGuang-II Upgrade laser facility.This work focused on the application of range-filter(RF)spectrometers,assembled from a 70 lm aluminum filter and two CR-39 nuclear track detectors,to measure the yields of primary DD-protons.Based on the track diameter calibration results of 3 MeV protons used to diagnose the tracks on the RF spectrometers,an approximate primary DD-proton yield of(8.5±1.7)×10^6 was obtained,consistent with the yields from similar laser facilities worldwide.This indicates that the RF spectrometer is an effective way to measure primary DD-protons.However,due to the low yields of D^3He-protons and its small track diameter,CR-39 detectors were unable to distinguish it from the background spots.Using other accurate detectors may help to measure these rare events.

New experimental measurement of^(nat)Se(n,γ)cross section between 1 eV to 1 keV at the CSNS Back-n facility

The^(74)Se is one of 35 p-nuclei,and^(82)Se is a r-process only nucleus,and their(n,γ)cross sections are vital input parameters for nuclear astrophysics reaction network calculations.The neutron capture cross section in the resonance range of isotopes and even natural selenium samples has not been measured.Promptγ-rays originating from neutron-induced capture events were detected by four C_(6)D_(6) liquid scintillator detectors at the Back-n facility of China Spallation Neutron Source(CSNS).The pulse height weighting technique(PHWT)was used to analyze the data in the 1 e V to 100 ke V region.The deduced neutron capture cross section was compared with ENDF/B-VIII.0,JEFF-3.2,and JENDL-4.0,and some differences were found.Resonance parameters were extracted by the R-matrix code SAMMY in the 1 e V-1 ke V region.All the cross sections ofnatSe and resonance parameters are given in the datasets.The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00019.

Pituitary-Thyroid Dysfunction in a Hashimoto’s Encephalopathy Patient

The pathogenesis of Hashimoto’s encephalopathy has not been clearly elucidated and involvement of autoimmune damage has been proposed. We report a 23-year-old man who was emergently hospitalized for paroxysmal syncope and involuntary tremor with normal physical examination except for low heart rate. The patient was characterized by neurological symptoms, mild hypothyroidism, enlarged pituitary gland and extremely elevated thyrotropin, which all were reversed with levothyroxine alone. The case indicated that the pituitary-thyroid dysfunction may play a role in the pathogenesis of Hashimoto’s encephalopathy, hence, evaluation of pituitary gland should be recommended in diagnosis and treatment of Hashimoto’s encephalopathy.

Recent progress in nuclear astrophysics research and its astrophysical implications at the China Institute of Atomic Energy

Nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth century.Broadly,it uses the laws of extremely small atomic nuclei to explain the evolution of the universe.Owing to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments,several critical astrophysical problems remain unsolved.To achieve a better understanding of astrophysics,it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical models.Direct measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions infuence stellar evolution.Given the challenges involved in measuring the extremely low crosssections of nuclear reactions in the Gamow peak and preparing radioactive targets,indirect methods,such as the transfer reaction,coulomb dissociation,and surrogate ratio methods,have been developed over the past several decades.These are powerful tools in the investigation of,for example,neutron-capture(n,r)reactions with short-lived radioactive isotopes.However,direct measurement is still preferable,such as in the case of reactions involving light and stable nuclei.As an essential part of stellar evolution,these low-energy stable nuclear reactions have been of particular interest in recent years.To overcome the diffculties in measurements near or deeply within the Gamow window,the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal solution.Therefore,underground experiments have emerged as a new and promising direction of research.In addition,to better simulate the stellar environment in the laboratory,research on nuclear physics under laser-driven plasma conditions has gradually become a frontier hotspot.In recent years,the CIAE team conducted a series of distinctive nuclear astrophysics studies,relying on the Jinping Underground Nuclear Astrophysics platform and accelerators in Earth’s surface laboratories,including the Beijing Radioactive Ion beam Facility,as well as other scientifc platforms at home and abroad.This research covered nuclear theories,numerical models,direct measurements,indirect measurements,and other novel approaches,achieving great interdisciplinary research results,with high-level academic publications and signifcant international impacts.This article reviews the above research and predicts future developments.

Miniature spectrometer based on a Fourier transform spectrometer chip and a commercial photodetector array

We demonstrate a novel type of miniature spectrometer based on a Fourier transform spectrometer(FTS)chip with a dense output array and a commercial photodetector(PD)array.The FTS chip has an output array cycle of 20μm and consists of 51 Mach–Zehnder interferometers(MZIs),and the PD array is a commercial linear charged coupled device(CCD).An achromatic triplet lens is used to image the MZI output interferogram onto the CCD with a small aberration.Our experiment result shows that a free spectral range(FSR)from 489 nm to 584 nm and a retrieved spectral resolution of 3.5nm at 532nm are obtained.The achieved properties show that our spectrometer has the potential to outperform the best commercial compact one in terms of most performance indices.

Shell-model study on properties of proton dripline nuclides with Z,N=30-50 including uncertainty analysis

The binding and proton separation energies of nuclides with Z,N=30-50 are investigated based on the shell model,with an uncertainty analysis via statistical methods.Several formulas are used to obtain the binding and proton separation energies according to shell-model calculations.The non-parametric bootstrap method is applied to establish an uncertainty decomposition and recomposition framework.Moreover,this is used to estimate the stability of proton(s) emission for each nuclide.Two formulas for calculating the binding energies with a systematic uncertainty of~0.3 Me V are proposed,and a reliable extrapolation ability is examined.These binding energy formulas deduce similar forms for their respective S_(p) and S_(2 p) energies,which predict the extension of the nuclear boundary of this region.A good description of the binding and proton separation energies is provided.The one-and twoproton separation energies and partial half-lives of proton emission are predicted,thus revealing a new dripline.Furthermore,there are 30 unstable nuclides predicted to be bound against proton(s)-emission.These nuclear properties will be useful in nuclear astrophysics.

Reevaluation of thermonuclear reaction rate of ^(50)Fe(p,γ)^(51)Co

The thermonuclear rate of the 50Fe（p, γ）51Co reaction in the Type I X-ray bursts （XRBs） temperature range has been reevaluated based on a recent precise mass measurement at CSRe Lanzhou, where the proton separa- tion energy Sp=142±77 keV has been determined firstly for the ~1Co nucleus. Comparing to the previous theoretical predictions, the experimental Sp value has much smaller uncertainty. Based on the nuclear shell model and mirror nuclear structure information, we have calculated two sets of thermonuclear rates for the 50Fe（p, γ）51Coreaction by utilizing the experimental Sp value. It shows that the statistical-model calculations are not ideally applicable for this reaction primarily because of the low density of low-lying excited states in 51Co. In this work, we recommend that a set of new reaction rates based on the mirror structure of 51Cr should be incorporated in future astrophysical network calculations.

A Novel Minkowski-distance-based Consensus Clustering Algorithm

Consensus clustering is the problem of coordinating clustering information about the same data set coming from different runs of the same algorithm. Consensus clustering is becoming a state-of-the-art approach in an increasing number of applications. However, determining the optimal cluster number is still an open problem. In this paper, we propose a novel consensus clustering algorithm that is based on the Minkowski distance. Fusing with the Newman greedy algorithm in complex networks, the proposed clustering algorithm can automatically set the number of clusters. It is less sensitive to noise and can integrate solutions from multiple samples of data or attributes for processing data in the processing industry. A numerical simulation is also given to demonstrate the effectiveness of the proposed algorithm. Finally, this consensus clustering algorithm is applied to a froth flotation process.

Thermal-optic tuning cascaded double ring optical sensor based on wavelength interrogation

Based on the Vernier effect of the cascaded double ring resonator(CDRR) sensor,a sensor consisting of a microfluidic control system,a sensing ring,and a reference ring with a micro-heater for thermal tuning is proposed in this paper.In wavelength interrogation,a broadband spectrometer or a large tunable range laser is not required.The shift of the output spectrum caused by the refractive index change of the sample is converted into the change of the electric power by the thermal tuning heater.Due to the Vernier effect,the sensitivity of the sensor is 20 times higher than that of the single ring.The spectral envelope of the thermal-optic tuning of the sensor was fitted by a Gaussian function in the wavelength range of8 nm.The experimental results showed that the sensitivity was 33.703 W/RIU,and the limit of detection was 1.34×10-5 RIU.

Asymptotic Property for Some Series of Probability

Abstract Let {X, Xn, n ≥ 1} be a sequence of i.i.d.random variables with zero mean, and set Sn = n∑k=1Xk, EX2 = σ2 〉 0, λ（ε） = ∞∑n=1P（1Sn1 ≥ ns）. In this paper, we discuss the rate of the approximation of σ2 by ε2= λ（s） under suitable conditions, and improve the corresponding results of Klesov （1994）.