Direct measurement of the break-out ^(19)F(p,γ)^(20)Ne reaction in the China Jinping underground laboratory(CJPL)

Calcium production and the stellar evolution of first-generation stars remain fascinating mysteries in astrophysics.As one possible nucleosynthesis scenario,break-out from the hot carbon–nitrogen–oxygen(HCNO)cycle was thought to be the source of the calcium observed in these oldest stars.However,according to the stellar modeling,a nearly tenfold increase in the thermonuclear rate ratio of the break-out ^(19)F(p,γ)^(20) Ne reaction with respect to the competing ^(19)F(p,α)^(16) O back-processing reaction is required to reproduce the observed calcium abundance.We performed a direct measurement of this break-out reaction at the China Jinping underground laboratory.The measurement was performed down to the low-energy limit of E_(c.m.)=186 keV in the center-of-mass frame.The key resonance was observed at 225.2 keV for the first time.At a temperature of approximately 0.1 GK,this new resonance enhanced the thermonuclear ^(19)F(p,γ)^(20) Ne rate by up to a factor of≈7.4,compared with the previously recommended NACRE rate.This is of particular interest to the study of the evolution of the first stars and implies a stronger breakdown in their“warm”CNO cycle through the ^(19)F(p,γ)^(20) Ne reaction than previously envisioned.This break-out resulted in the production of the calcium observed in the oldest stars,enhancing our understanding of the evolution of the first stars.

Design and construction of charged-particle telescope array for study of exotic nuclear clustering structure

The exploration of exotic shapes and properties of atomic nuclei,e.g.,αcluster and toroidal shape,is a fascinating field in nuclear physics.To study the decay of these nuclei,a novel detector aimed at detecting multipleα-particle events was designed and constructed.The detector comprises two layers of double-sided silicon strip detectors(DSSD)and a cesium iodide scintillator array coupled with silicon photomultipliers array as light sensors,which has the advantages of their small size,fast response,and large dynamic range.DSSDs coupled with cesium iodide crystal arrays are used to distinguish multipleαhits.The detector array has a compact and integrated design that can be adapted to different experimental conditions.The detector array was simulated using Geant4,and the excitation energy spectra of someα-clustering nuclei were reconstructed to demonstrate the performance.The simulation results show that the detector array has excellent angular and energy resolutions,enabling effective reconstruction of the nuclear excited state by multipleαparticle events.This detector offers a new and powerful tool for nuclear physics experiments and has the potential to discover interesting physical phenomena related to exotic nuclear structures and their decay mechanisms.

Fudan multi-purpose active target time projection chamber(fMeta-TPC)for photonuclear reaction experiments

Active target time projection chambers are state-of-the-art tools in the field of low-energy nuclear physics and are particularly suitable for experiments using low-intensity radioactive ion beams or gamma rays.The Fudan multi-purpose active target time projection chamber(fMeta-TPC)with 2048 channels was developed to studyα-clustering nuclei.This study focused on the photonuclear reaction with a laser Compton scattering gamma source,particularly for the decay of the highly excitedαcluster state.The design of fMeta-TPC is described in this paper.A comprehensive evaluation of its offline performance was conducted using an ultraviolet laser and ^(241)Amαsource.The results showed that the intrinsic angular resolution of the detector was within 0.30°,and the detector had an energy resolution of 6.85%for 3.0 MeVαparticles.The gain uniformity of the detector was approximately 10%(RMS/Mean),as tested by the ^(55)Fe X-ray source.

Properties of the QCD matter:review of selected results from the relativistic heavy ion collider beam energy scan(RHIC BES)program

In the paper,we discuss the development of the multigap resistive plate chamber time-of-fight(TOF)technology and the production of the solenoidal tracker at RHIC(STAR)TOF detector in China at the beginning of the twenty-frst century.Subsequently,recent experimental results from the frst beam energy scan program(BES-I)at the Relativistic Heavy Ion Collider(RHIC)pertaining to measurements of collectivity,chirality,criticality,global polarization,strangeness,heavy favor,dilepton and light nuclei productions are reviewed.

Correction to:Feasibility study of the photonuclear reaction cross section of medical radioisotopes using a laser Compton scattering gamma source

Correction to:Nuclear Science and Techniques(2024)35:155 https://doi.org/10.1007/s41365-024-01481-7 In Eq.(2)of this article,the term'i'should be denoted as a subscript,the corrected equation should read N_(0)=σ(E)N_(t)QC_(kbeam)^(e^(-λt_(i)))∫_(0)^(t_(i))e^(λt)dt,(2)The original article has been corrected.

Predictions of nuclear charge radii based on the convolutional neural network

In this study, we developed a neural network that incorporates a fully connected layer with a convolutional layer to predict the nuclear charge radii based on the relationships between four local nuclear charge radii. The convolutional neural network(CNN) combines the isospin and pairing effects to describe the charge radii of nuclei with A ≥ 39 and Z ≥ 20. The developed neural network achieved a root mean square(RMS) deviation of 0.0195 fm for a dataset with 928 nuclei. Specifically, the CNN reproduced the trend of the inverted parabolic behavior and odd–even staggering observed in the calcium isotopic chain, demonstrating reliable predictive capability.

Progress in ab initio in-medium similarity renormalization group and coupled-channel method with coupling to the continuum

Over the last decade,nuclear theory has made dramatic progress in few-body and ab initio many-body calculations.These great advances stem from chiral efective feld theory(xEFT),which provides an efcient expansion and consistent treatment of nuclear forces as inputs of modern many-body calculations,among which the in-medium similarity renormalization group(IMSRG)and its variants play a vital role.On the other hand,signifcant eforts have been made to provide a unifed description of the structure,decay,and reactions of the nuclei as open quantum systems.While a fully comprehensive and microscopic model has yet to be realized,substantial progress over recent decades has enhanced our understanding of open quantum systems around the dripline,which are often characterized by exotic structures and decay modes.To study these interesting phenomena,Gamow coupled-channel(GCC)method,in which the open quantum nature of few-body valence nucleons coupled to a deformed core,has been developed.This review focuses on the developments of the advanced IMSRG and GCC and their applications to nuclear structure and reactions.

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.

Neutron skin and its effects in heavy-ion collisions

Neutron skin is an exotic phenomenon that occurs in unstable nuclei.In this study,the various efects of the neutron skin on nuclear reactions and their relationship with the properties of nuclear structures are reviewed.Based on numerous studies using theoretical models,strong correlations have been found between the neutron skin thickness and the neutron removal cross section,neutron/proton yield ratio,t∕3He yield ratio,neutron-proton momentum diference,isoscaling parameter,photon production,reaction cross sections for neutron-induced reactions,charge-changing cross-sectional diferences of mirror nuclei,astrophysical S-factor,and other quantities in nuclear reactions induced by neutron-rich nuclei.Moreover,the relationships between the neutron skin thickness and certain properties of the nuclear structure,such asα-cluster formation,αdecay,nuclear surface,nuclear temperature,and proton radii diference of mirror nuclei,have also been investigated.Furthermore,it has also been shown that the neutron skin plays a crucial role in relativistic heavy-ion collisions.Experimentally,an unstable nucleus with a neutron skin can be generated by radioactive nuclear beam facilities,and the thickness of the neutron skin can be extracted by measuring the sensitive probes,which further helps impose stringent constraints on the equation of state of asymmetric nuclear matter and the properties of neutron stars.

Quantifying the strength of magnetic fields using baryon electric charge correlation

Although heavy-ion collisions generate strong magnetic fields,their direct measurement is a challenging task.A new observable,the baryon electric charge correlation,was recently found to be sensitive to the magnetic field strength and thus could be used as a magnetometer for heavy-ion collisions.Additionally,this observable may shed light on the equation of state and phase structure of quantum chromodynamics(QCD)under magnetic fields.Determining and understanding the phase structure of quantum chromodynamics(QCD)is important in contemporary physics[1].

Production and test of sPHENIX W/SciFiber electromagnetic calorimeter blocks in China

The sPHENIX experiment is a new generation of large acceptance detectors at the relativistic heavy ion collider at Brookhaven National Laboratory,with scientific goals focusing on probing the strongly interacting Quark–Gluon plasma with hard probes of jets,open heavy flavor particles,andγproduction.The EMCal detector,which covers the pseudo-rapidity region of|η|≤1.1,is an essential subsystem of sPHENIX.In this study,we focused on producing and testing EMCal blocks covering a pseudo-rapidity of|η|∈[0.8,1.1].These,in conjunction with the central pseudo-rapidity EMCal blocks,significantly enhance the sPHENIX physics capability of the jet andγparticle measurements.In this paper,the detector module production and testing of sPHENIX W-powder/scintillating fiber(W/ScFi)electromagnetic calorimeter blocks are presented.The selection of the tungsten powder,mold fabrication,QA procedures,and cosmic ray test results are discussed.

Correction to:Production and test of sPHENIX W/SciFiber electromagnetic calorimeter blocks in China

Correction to:Nuclear Science and Techniques(2024)35:145 https://doi.org/10.1007/s41365-024-01517-y In this article the author’s name Wan-Bing He was incorrectly written as Wan-Bin He.The original article has been corrected.

Measurement of Br(n,γ)cross sections up to stellar s-process temperatures at the CSNS Back‑n

The neutron capture cross sections(n,γ)of bromine were obtained using the time-of-flight technique at the Back-n facility of the China Spallation Neutron Source.Promptγ-rays originating from neutron-induced capture events were detected using four C_(6)D_(6) detectors.The pulse-height weighting technique and double-bunch unfolding method based on Bayesian theory were used in the data analysis.Background deductions,normalization,and corrections were carefully considered to obtain reliable measurement results.The multilevel R-matrix Bayesian code SAMMY was used to extract the resonance parameters in the resolved resonance region(RRR).The average cross sections in the unresolved resonance region(URR)were obtained from 10 to 400 keV.The experimental results were compared with data from several evaluated libraries and previous experi-ments in the RRR and URR.The TALYS code was used to describe the average cross sections in the URR.The astrophysical Maxwell average cross sections(MACSs)of ^(79,81)Br from kT=5 to 100 keV were calculated over a sufficiently wide range of neutron energies.At a thermal energy of kT=30 keV,the MACS value for ^(79)Br 682±68 mb was in good agreement with the KADoNiS v1.0 recommended value.By contrast,the value of 293±29 mb for ^(81)Br was substantially higher than that of the evaluated database and the KADoNiS v1.0 recommended value.

Measurements of absolute electron capture cross sections in He^(2+)–He and Ne^(8+)–O_(2'), N_(2'), CH_4 collisions

The total absolute cross sections of single-and double-electron capture (SEC and DEC) in the collisions of He^(2+)with He and Ne^(8+)with O_(2),N_(2),and CH_(4) were studied in the energy ranges 3.5–50 keV/u and 2.8–40 keV/u,respectively.Through a deep analysis of the experimental systematic uncertainties in the measurement procedure and data evaluation,the error in the experimental results of the SEC cross sections is less than 9%.Within the uncertainties,the present results of the He^(2+)–He collision show good consistency with previous measurements,validating the experimental system and paving the way for precise measurements of EC cross sections for a variety of ions and neutral gases.The present measurements allow for a test of EC theory and provide crucial EC cross section data for the establishment of plasma models in fusion research and astrophysical X-ray studies.

Properties of QCD matter:a review of selected results from ALICE experiment

The Large Hadron Collider(LHC), the world's largest and most powerful particle accelerator, has been a pivotal tool in advancing our understanding of fundamental physics. By colliding heavy ions, such as lead ions, the LHC recreates conditions similar to those just after the Big Bang. This allows scientists to study the quark-gluon plasma(QGP), a state of matter in which quarks and gluons are not confned within protons and neutrons. These studies provide valuable insights into the strong force and the behavior of the early universe. In this paper, we present a comprehensive overview of recent signifcant fndings from A Large Ion Collider Experiment(ALICE) at the LHC. The topics covered include measurements related to the properties of the QGP, particle production, fow and correlations, dileptons, quarkonia, and electromagnetic probes, heavy favor, and jets. Additionally, we introduce future plans for detector upgrades in the ALICE experiment.

New type of double‑slit interference experiment at Fermi scale

A new approach that using polarized photon–gluon collisions reported by STAR Collaboration is used to do tomography of the ultrarelativistic nucleus.The collision can be treated as a double-slit experiment at Fermi scale and solves a mystery last over 20 years in extracting the nuclear radius via vector meson photoproduction.

Design and performance of a high-speed and low-noise preamplifier for SiPM

Considering the R&D for upgrading the K^(0)_(L) andμdetectors in the Belle II experiment using a scintillator and silicon pho-tomultiplier(SiPM),we designed a compact high-speed and low-noise preamplifier.The preamplifier demonstrated a good gain stability,bandwidth of 426 MHz,baseline noise level ofσ≈0.6 mV,dynamic range of up to170 mV of the input signal amplitude,good time resolution of 20 ps,and it can be comprehensively applied to SiPMs.Adopting pole-zero-cancelation in the preamplifier reduces both the rise and fall times of the SiPM signal,which can significantly improve the time resolution and reduce the pile-up when using a large SiPM or an array of SiPMs.Various combinations of the preamplifier and several types of SiPMs demonstrated time resolutions better than 50 ps for most cases;when the number of detected photons was larger than 60,a time resolution of approximately 25 ps was achieved.