Nuclear Physics Facility Research Articles

Overview of High-Performance Timing and Position-Sensitive MCP Detectors Utilizing Secondary Electron Emission for Mass Measurements of Exotic Nuclei at Nuclear Physics Facilities

Timing and/or position-sensitive MCP detectors, which detect secondary electrons (SEs) emitted from a conversion foil during ion passage, are widely utilized in nuclear physics and nuclear astrophysics experiments. This review covers high-performance timing and/or position-sensitive MCP detectors that use SE emission for mass measurements of exotic nuclei at nuclear physics facilities, along with their applications in new measurement schemes. The design, principles, performance, and applications of these detectors with different arrangements of electromagnetic fields are summarized. To achieve high precision and accuracy in mass measurements of exotic nuclei using time-of-flight (TOF) and/or position (imaging) measurement methods, such as high-resolution beam-line magnetic-rigidity time-of-flight (Bρ-TOF) and in-ring isochronous mass spectrometry (IMS), foil-MCP detectors with high position and timing resolution have been introduced and simulated. Beyond TOF mass measurements, these new detector systems are also described for use in heavy ion beam trajectory monitoring and momentum measurements for both beam-line and in-ring applications. Additionally, the use of position-sensitive timing foil-MCP detectors for Penning trap mass spectrometers and multi-reflection time-of-flight (MR-TOF) mass spectrometers is proposed and discussed to improve efficiency and enhance precision.

Acceleration of uranium beam to record power of 10.4 kW and observation of new isotopes at Facility for Rare Isotope Beams

The Facility for Rare Isotope Beams (FRIB) is a major nuclear physics facility for research with fast, stopped, and reaccelerated beams that was successfully commissioned in May 2022. A key capability of FRIB is the production of an acceleration of the uranium beam, but this capability requires the facility to work at the design limits of the lowest charge-to-mass ratio and the highest power density on the beam intercepting devices. This paper presents techniques for overcoming the significant challenges in accelerating the uranium beam, culminating in the demonstration of 10.4 kW on target, and the discovery of three new isotopes. The high-power uranium beam enabled us to produce and identify G88a, A93s, and S96e, within the first 24 h of operation. The successful uranium operation at FRIB sets a new record for accelerated uranium beam power above 10 kW and opens a new avenue of research with rare isotopes. Published by the American Physical Society 2024

Design of a novel ECR ion trap facility for nuclear physics and fundamental plasma processes studies

An innovative ECR ion trap facility, called PANDORA (Plasma for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry), was designed for fundamental plasma processes and nuclear physics investigations. The overall structure consists of three subsystems: a) a large (70 cm in length, 28 cm in inner diameter) ECR plasma trap with a fully superconducting B-minimum magnetic system (Bmax = 3.0 T) and an innovative design to host detectors and diagnostic tools; b) an advanced non-invasive plasma multidiagnostics system to locally characterize the plasma thermodynamic properties; c) an array of 14 HPGe detectors. The PANDORA facility is conceived to measure, for the first time, in-plasma β-decaying isotope rates under stellar-like conditions. The experimental approach consists in a direct correlation of plasma parameters and nuclear activity by disentangling - by means of the multidiagnostic system that will work in synergy with the γ-ray array - the photons emitted by the plasma (from microwave to hard X-ray) and γ-rays emitted after the isotope β-decay. In addition to nuclear physics research, fundamental plasma physics studies can be conducted in this unconventional ion source equipped with tens of detection and diagnostic devices (RF polarimeter, optical emission spectroscopy (OES), X-ray imaging, space and time-resolved spectroscopy, RF probes, scope), with relevant implications for R&D of ion sources for accelerator physics and technology. Several studies have already been performed in downsized nowadays operating ECRIS. Stable and turbulent plasma regimes have been described quantitatively, studying the change of plasma morphology, confinement, and dynamics of losses using space resolved X-ray spectroscopy.

Short-range correlations in dynamical intranuclear cascade models for describing nucleon knockout reactions

Spallation and fragmentation reactions at incident energies above the Fermi momentum are considered to be the main mechanism for the production of neutron-rich nuclei at worldwide nuclear physics facilities, such as RIBF, FRIB, and GSI-FAIR. Although it is widely known that dynamical reaction models give a rather good prediction of cross sections for nuclear residues produced in spallation and fragmentation reactions, these reaction models fail in the description of peripheral collisions involving short-range nucleon-nucleon correlations (SRCs). Here, we present state-of-the-art dynamical reaction calculations based on the intranuclear cascade approach to describe spallation and fragmentation reactions. The new version of our dynamical model, including SRCs, successfully describes isotopic cross sections of neutron-rich nuclear residues and inclusive single-neutron and single-proton knockout cross sections for various stable and exotic nuclei. Finally, the results show that the systematic strong dependency of the single-knockout cross section reduction factor on the neutron-proton separation energy asymmetry parameter (ΔS) obtained by Tostevin and Gade disappears when SRCs are taken into account.

The high-performance DIRC for the ePIC detector at the EIC

The next-generation nuclear physics facility in the United States will be the Electron-Ion Collider (EIC), scheduled to be built at Brookhaven National Laboratory (BNL). Excellent particle identification (PID) is one of the key requirements for the EIC central detector called ePIC. Identification of the hadrons in the final state is critical to study how different quark flavors contribute to nucleon properties. A detector using the Detection of Internally Reflected Cherenkov light (DIRC) principle, with a radial size of only 7-8 cm, was chosen as the PID system for the ePIC barrel region. Within the framework of the EIC R&D programs, the development of a high-performance DIRC (hpDIRC) detector was undertaken with the aim of significantly advancing state-of-the-art performance. Key components of the hpDIRC detector are a 3-layer compound lens and small pixel-size photo sensors. Currently, the hpDIRC R&D program is focused on developing and validating the radiation hard 3-layer lens, quality assurance of the BaBar DIRC radiation bars, and the early stage of the hpDIRC prototype program with Cosmic Ray Telescope at Stony Brook University, in preparation for beam tests at Fermilab in 2024.

Latest results from the RD42 collaboration on the radiation tolerance of polycrystalline diamond detectors

As nuclear and particle physics facilities move to higher intensities, the detectors used there must be more radiation tolerant. Diamond is in use at many facilities due to its inherent radiation tolerance and ease of use. In this article we present our radiation tolerance measurements of the highest quality polycrystalline Chemical Vapor Deposition (pCVD) diamond material for irradiations from a range of proton energies, pions and neutrons up to a fluence of 2×1016particles/cm2. We have measured the damage constant as a function of energy and particle species and compared it with theoretical models. We also present measurements of the rate dependence of pulse height for non-irradiated and irradiated pCVD diamond pad and pixel detectors, including detectors tested over a range of particle fluxes up to 20 MHz/cm2 with both pad and pixel readout electronics. Our test beam results indicate a 2% upper limit to the pulse height dependence of unirradiated and neutron irradiated pCVD diamond detectors leading to the conclusion that the pulse height in pCVD diamond detectors is, at most, minimally dependent on the particle flux.

Drift-free, 11 fs pulse delay stability in dual-arm PW-class laser systems

Abstract Simultaneous ultra-intense pulses at petawatt laser facilities enable a broad range of experiments in nuclear photonics and strong field quantum electrodynamics. These experiments often require very precise control of the time delays between pulses. We report measurements of the time delay between the two 1 PW outputs of the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility in Romania. The short-term standard deviation of the time delay was approximately half of the pulse duration of 23 fs, and the average delay drifted with up to 100 fs/h. The drift and sporadic delay jumps were corrected using a feedback loop, which reduced the long-term standard deviation of the delay close to its short-term value. These results imply that in ELI-NP experiments using two simultaneous pulses, a temporal overlap of better than half of the pulse duration can be achieved for more than two thirds of the shots, which would enable high data rate experiments using simultaneous petawatt pulses.

Accelerator and beam physics challenges in support of FRIB experiments

The Facility for Rare Isotope Beams (FRIB), a major nuclear physics facility for research with fast, stopped and reaccelerated rare isotope beams, started operation in May 2022. Since then, a dozen nuclear physics experiments have been successfully accomplished. Typically, the experiments with rare isotope beams last a week or two. Each experiment requires a different primary beam species and energies. Shortening the accelerator and fragment separator setup time is critical to meet the demands of the FRIB Users community. Currently, the primary focus in the linac is reducing the accelerator setup time and beam power ramp-up. Many physics applications have been developed and used to set up the accelerator and beamlines. The simultaneous acceleration of multiple charge states of heavy ion beams is routinely used to minimize the beam power deposition on the charge selector slits after the stripper. This paper discusses the challenges of linac tune development for the acceleration of various ion species.

The annealing setup and associated monitoring system of the ELIADE HPGe clover detectors at ELI-NP

We report a dedicated setup built in-house for the annealing of the HPGe clover detectors of the ELI-NP Array of DEtectors (ELIADE) γ-ray spectrometer, as well as the post-annealing testing of these detectors with the standard 60Co & 152Eu radioactive calibration sources employing conventional analog electronics. Both the design and assembly of the annealing setup were performed at the Extreme Light Infrastructure — Nuclear Physics (ELI-NP) facility, Măgurele, Romania. A `radiation damage annealing assembly kit' (NRK-200 unit) from the detector manufacturer Canberra is utilized in heating and controlling the temperature of the Ge crystals of the annealed detector. The vacuum inside the detector was maintained throughout the annealing process by constantly pumping the system using a turbo-molecular pumping station. The temperature of the germanium crystals, located inside a vacuum sealed chamber, of the detector and the vacuum level of this chamber were monitored throughout the annealing process, via both in-person observation and remote (online) monitoring. The Graphic User Interface (GUI) of an underlying LabVIEW script was utilized for running the monitoring process of the temperature and vacuum pressure values via a local network. To have the option of real-time online monitoring of the temperature, vacuum pressure, we coupled the web application Grafana with the Influx DB of the annealing data, as well as the backup time information of an Uninterruptible Power Supply (UPS) unit used in system.

What can we learn from experiments with high-brilliance gamma beams?

An overview of the main directions of present-day studies with quasimonochromatic γ beams is presented with an emphasis on the research opportunities which will be provided to the users at the Extreme Light Infrastructure Nuclear Physics (ELI-NP) facility at Magurele near Bucharest. Experiments with γ beams at the extremes of high temperature and high neutron-to-proton ratios will be discussed. The opportunities for nuclear structure studies with γ rays with orbital angular momentum (OAM) are outlined and a few selected physics problems and classes of experiments, related to, e.g., changes of photonuclear cross sections in reactions with OAM photons, as well as the possibility to address nuclear excitations with higher multipolarity are discussed. The perspectives for studies of exotic nuclei within the Gamma Factory experiment at CERN are discussed, too.

Zernike-coefficient extraction via helical beam reconstruction for optimization (ZEHBRO) in the far field

Abstract The spatial distribution of beams with orbital angular momentum in the far field is known to be extremely sensitive to angular aberrations, such as astigmatism, coma and trefoil. This poses a challenge for conventional beam optimization strategies when a homogeneous ring intensity is required for an application. We developed a novel approach for estimating the Zernike coefficients of low-order angular aberrations in the near field based solely on the analysis of the ring deformations in the far field. A fast, iterative reconstruction of the focal ring recreates the deformations and provides insight into the wavefront deformations in the near field without relying on conventional phase retrieval approaches. The output of our algorithm can be used to optimize the focal ring, as demonstrated experimentally at the 100 TW beamline at the Extreme Light Infrastructure - Nuclear Physics facility.

Nuclear astrophysics studies with γ-ray beams: What do we expect to learn from them?

An overview of the main directions of present-day studies with quasimonochromatic γ beams is discussed with an emphasis on the research opportunities which will be offered at the Extreme Light Infrastructure Nuclear Physics (ELI-NP) facility at Magurele near Bucharest in Romania. Experiments with γ beams at the extremes of high temperatures are outlined, with an emphasis on prospective studies related to nuclear astrophysics and astroparticle physics. Some of the experimental setups for nuclear structure, reaction, and astrophysics studies, which are available at ELI-NP, are described.

Ensuring the unity of measurements of the neutron radiation rate absorbed dose in the field of clinical neutron radiation dosimetry

Development of neutron radiation therapy arises the question of ensuring the uniformity of measurements of the absorbed dose and the absorbed dose rate of neutron radiation. FGUP “VNIIFTRI” improved the primary method and means of reproducing the unit of neutron radiation absorbed dose rate within the framework of improving the State primary standard of units of absorbed dose rate and neutron dose equivalent rate GET 117-2010. A set of ionization chambers has been created and the upper value of the reproduction of the unit of absorbed dose rate of neutron radiation has been expanded. A hardware-methodical complex has also been developed for transferring a unit of absorbed dose rate of neutron radiation to nuclear physics facilities used in neutron radiation therapy. As a result the expanded relative uncertainty of reproduction of the unit of absorbed dose rate does not exceed 3%, the expanded relative uncertainty of the transmission method does not exceed 0.5%. The resulting level of accuracy is in line with the recommendations used in neutron beam therapy.

Nuclear medium effects in lepton-nucleus DIS in the region of x≳1

The nuclear medium effects in the nuclear structure functions and differential cross sections in the deep inelastic scattering (DIS) of charged lepton and neutrino from nuclear targets are studied in the region of large $x$ including $x\ge 1$. The nuclear medium effects due to the Fermi motion and the binding energy of nucleons and the nucleon correlations are included using nucleon spectral function calculated in a microscopic field theoretical model. The numerical results for the nuclear structure functions and the cross sections are obtained using the nucleon structure function evaluated at the next-to-next-to-leading order (NNLO) with the Martin-Motylinski-Harland Lang-Thorne (MMHT) parameterization of the nucleonic parton distribution functions (PDFs) and are compared with the available experimental data on electron scattering from the Jefferson Lab (JLab) and SLAC Nuclear Physics Facility (NPAS). In the case of neutrino scattering the results are relevant for understanding the DIS contributions to the recent inclusive cross sections measured by the Main Injector Neutrino ExpeRiment to study v-A interactions (MINERvA) as well as theoretical predictions are made for Deep Underground Neutrino Experiment (DUNE). The importance of isoscalarity corrections in heavier nuclear targets as well as the effect of the kinematic cut on the CM energy $W$ in defining the DIS region have also been discussed.

High voltage dc gun for high intensity polarized electron source

The high intensity polarized electron source is a critical component for future nuclear physics facilities. The Electron Ion Collider (EIC) requires a polarized electron gun with higher voltage and higher bunch charge compared to any existing polarized electron source. At Brookhaven National Laboratory, we have built an inverted high voltage direct current (HVDC) photoemission gun with a large cathode size. We report on the performances of GaAs photocathodes in a high gradient with up to a 16 nC bunch charge. The measurements were performed at a stable operating gap voltage of 300 kV - demonstrating outstanding lifetime, and robustness. We observed obvious lifetime enhancement by biasing the anode. The gun also integrated a cathode cooling system for potential application on high current electron sources. The various novel features implemented and demonstrated in this polarized HVDC gun open the door towards future high intensity-high average current electron accelerator facilities.

10 PW peak power femtosecond laser pulses at ELI-NP

AbstractWe report on the generation and delivery of 10.2 PW peak power laser pulses, using the High Power Laser System at the Extreme Laser Infrastructure – Nuclear Physics facility. In this work we demonstrate for the first time, to the best of our knowledge, the compression and propagation of full energy, full aperture, laser pulses that reach a power level of more than 10 PW.

Experimental programme with high-brilliance gamma beams at ELI-NP

The emerging experimental program with brilliant gamma beams at the Extreme Light Infrastructure – Nuclear Physics (ELI-NP) facility is presented with emphasis on the day-one experiments which are under preparation. Experiments at ELI-NP will cover nuclear resonance fluorescence (NRF) measurements, studies of large-amplitude motions in nuclei, photo-fission and photonuclear reactions of astrophysics interest, and measurements of photonuclear reaction cross-sections. The physics cases of the flagship experiments at ELI-NP and the performance of the related instruments, which are under construction for their realization, are discussed.

Major Accelerator Facilities for Nuclear Physics in Asia Pacific

Asian Nuclear Physics Association (ANPhA) is the central organization representing nuclear physics in Asia Pacific. ANPhA is now preparing a list of accelerators applicable for nuclear physics experiments in Asia Pacific. Among the listed facilities, world-class “major” accelerator facilities are mainly located in China (Heavy Ion Research Facility in Lanzhou (HIRFL), and its future extension in Huizhou, i.e. HIAF/CiADS, Beijing Tandem Accelerator National Laboratory (BTANL), which is now upgraded to Beijing RI beam Facility (BRIF), in India (Variable Energy Cyclotron Centre (VECC) in Kolkata), in Korea (RISP/rAoN), and in Japan (RIBF at Riken, J-PARC, RCNP, and ELPH/LEPS). World class facilities based on the tandem accelerator are locating at Mumbai and New Deli in India, at Tokai-mura in Japan, and at Canberra in Australia. Characteristics of these “majof” facilities including their facility developments will briefly be reviewed in comparing with similar facilities in Europe and North America.

Research program of nuclear astrophysics based on the HIAF

Nuclear astrophysics is an interdisciplinary research field integrating nuclear physics, astrophysics and astronomy. It has always been an important frontier of physics in the world. This paper summarizes the current status, key research topics, and experimental approaches in nuclear astrophysics and briefly introduces its research prospect based on the High Intensity heavy-ion Accelerator Facility (HIAF), which is a large-scale scientific facility for nuclear physics that is under construction in China. HIAF has great advantages for studying the masses, half-life, and reaction cross sections of the unstable nuclides and will provide a good opportunity for understanding explosive nuclear processes as well as the origin of heavy elements in the universe. For key reactions in the nucleosynthesis process, indirect measurement methods and experimental techniques such as ANC, Oslo, surrogate reactions, and surrogate ratio methods, will be developed and used for the systematic studies on the charged-particle or neutron capture reactions. Using the HIAF storage ring, the mass of the r-process nuclides can be systematically measured. Using the HIAF secondary beam line and high-efficiency detector, the decay half-life of the r-process nuclides can be measured. Furthermore, based on HIAF, the equations of states of a neutron star and weak interaction rates can be studied. Using the above nuclear physics experimental and theoretical research, the database of the masses and reaction rates will be updated. Astronomical observations will be combined to test the astrophysical model, and to understand the evolution of stars as well as the origin of elements in the universe.

Charge-changing cross section measurements of atomic nuclei and charge radii

<p indent=0mm>The atomic nucleus is a finite open quantum many-body system that is composed of two basic building blocks, proton and neutron. Like many systems governed by the laws of quantum mechanics, a nucleus is an object full of mysteries. Nuclear properties and structure are much more difficult to characterize than those of macroscopic objects and it is almost impossible to build an exact replica of this Fermi-scale nuclear system. In reality, physicists have developed an approach to reveal nature by collisions of two atomic nuclei, i.e., nuclear reactions, since the very beginning of nuclear physics. One famous example is the Rutherford scattering experiment performed at around 1910, in which the nuclide as a core of atom was discovered. Since the late 1980s, precision measurements of reaction cross section or interaction cross sections played a crucial role in nuclear size determination. This was entwined with the realization of radioactive ion beams (RIB). Such measurements contributed to discovering, for example, the neutron skin and neutron halo, when moving far away from the stability line. The new phenomena and properties found along the experimental advance are meanwhile among the strongest motivations for initiating, constructing, and operating the new generations of nuclear physics facilities worldwide. HIAF, the High-Intensity heavy-ion Accelerator Facility, is now under construction in Huizhou, China. In the last few years, systematic measurements of charge-changing cross sections (CCCS) of exotic nuclei have attracted much attention. It offers a complementary way to study exotic structures that could exist in exotic nuclei. By definition, CCCS refers to the total probability of removing at least one proton from the projectile nuclide. It reflects the geometric overlapping area during the collision. In particular, by combining with the Glauber-type model calculations, precise CCCS data have been used as an effective probe to investigate the proton density distribution of unstable atomic nuclei. This method is suitable for the investigation of exotic nuclei with low production yields, and the measurements accordingly were proposed in almost all the major nuclear physics facilities in the last years. In this paper, we first attempted to give a review on the progress of CCCS worldwide, from the pioneering work of RIB physics in the 1980s to the recent advances towards neutron-rich nuclei. Then we introduced the experimental work performed at the Heavy Ion Research Facility at Lanzhou (HIRFL). So far, CCCSs of more than 30 light nuclei have been determined and most of them are along the β-stability line. Based on the same setup, the Beihang group will focus on the CCCS measurements of sd-shell nuclei, aiming to study the (sub-)shell structure at 14 and 16. After surveying the existing CCCS data worldwide, it is found that there are often large deviations among various measurements in different laboratories even for the simplest reaction system. Precision data are therefore urgently called to clarify the deviations in existing data and to constrain the reaction mechanism on hydrogen targets. From my point of view, simultaneous measurements of both CCCS and reaction cross section in particular on hydrogen targets, the simplest target composed of only protons, are expected to enhance dramatically the journey to reveal the nature of very exotic nuclei. In the last part of this paper, perspectives at the High-energy FRagment Separator (HFRS) at HIAF are discussed. After a careful design of the detector setup and data taking system, it is possible to open a new era of nuclear physics experiments, in which various types of experiments can be carried out simultaneously.