This work was partly supported by the U.S. National Science Foundation awards NSF PHY-1565546, NSF PHY-1936404, NSF PHY-2011265, NSF PHY-2011398, and NSF PHY-2012040.
Spectroscopy of neutron unbound 13Be can provide insights into the unexpected structural changes of neutron-rich nuclei around N=8. Invariant mass spectra from past experiments do not agree on the location of the...
In light nuclei, the quantum states formed near the cluster-separation threshold favor a large degree of cluster configurations. The $^{10}$Be is a well-known cluster nucleus, with a set of states having very large $\alpha$ widths and very small neutron strengths, consistent with the valence neutrons orbiting around the 2-$\alpha$ cores. The cluster decay branching ratios and cluster content...
Historically, the N=20 region of the nuclear chart has played a significant role in our understanding of nuclear structure. In this mass region, deformed excited states from neutron occupations in the νf7/2 orbital are observed to compete with normal configurations in the sd-shell leading to so-called intruder-states. Interestingly, this large evolution of shell structure is not a...
Beta-decay rates are key quantities to understand both nuclear structure properties as well as the dynamics of nucleosynthesis processes. However, microscopic calculations based on the evaluation of nuclear matrix elements using eigenstates of the mother and daughter nuclei separately are scarce.
From a beyond-mean-field point of view, one of the main problems is the evaluation of the...
Beta-decay strength measurements are required to constrain the nuclear models, which aim to predict nuclear lifetimes and decay branching ratios. Recently, this became an important research topic, especially for neutron-rich nuclei, relevant to the r-process. We studied beta delayed neutron emission of neutron-rich cobalt isotopes to (Z=28) nickel nuclei to complete the strength distribution...
The 15O(α,γ)19Ne breakout reaction from the hot CNO cycles is significant to the thermonuclear runaway that causes type I X-ray bursts on accreting neutron stars. At breakout temperatures (≈0.5GK), this reaction is strongly dominated by a single resonance with center of mass energy 506 Kev corresponding to a 19Ne state having excitation energy of 4.03 MeV. An experimental upper limit has been...
Skutek Instrumentation excels in development of multichannel, high-performance digitizers described in the companion poster. Data readout is facilitated through 10G optical or 1G copper Ethernet from each individual device. High-volume data streams are received by Data Collection Computers followed by Data Transfer Nodes, and buffered on local high-capacity disk arrays. The data sets will be...
At TRIUMF, Canada’s particle accelerator centre, the TIGRESS Integrated Plunger (TIP) and its configurable detector systems have been used for charged-particle tagging and light-ion identification in Doppler-shift lifetime measurements using gamma-ray spectroscopy with the TIGRESS array of HPGe detectors. An experiment using these devices to measure the lifetime of the $2^+_1$ state of...
Neutron rich Mg isotopes far from stability belong to the island of inversion, a region where the configuration of single-particle nucleon states becomes inverted with respect to the predicted ordering of the spherical shell model. Nuclei in this region also exhibit collective behaviour in which multiple particle interactions play a significant role in nuclear wavefunctions and transitions....
The nuclear level density is an important input in nuclear reaction codes to calculate reaction cross sections. Experimental data are limited and theoretical models suffer from large uncertainties. This motivates further experimental studies.
The data on the level density and the spin cutoff parameter for the $\rm ^{59}Ni$ isotope were obtained from the analysis of the angular distribution...
Fusion evaporation reaction induced by a beam of 43MeV $^{14}$C on $^{48}$Ti and $^{50}$Ti targets has been used to populate the high spin levels in $^{59}$Co and $^{61}$Co. Emitted γ rays were detected using the FSU clover array which consists of 6 high purity germanium clover detectors (with BGO shields for Compton suppression) and a few single-crystal detectors all placed at 3 different...
Alpha-, beta-, and proton-decay energies have been combined with TITAN mass values for 150−157Yb to expand and refine the mass surface in the proton-rich Z = 70 − 82 region. The calculations were performed using the Atomic Mass Evaluation (AME) algorithm. As a result, a total of 11 new ground state masses were accordingly determined while the uncertainties were reduced by more than...
Carbon burning is a key step in the evolution of massive stars, Type 1a supernovae and superbursts in x-ray binary systems. Determining the $^{12}$C+$^{12}$C fusion cross section at energies relevant to these different astrophysical scenarios by extrapolation of direct measurements is challenging due to resonances at and below the Coulomb barrier.
A study of the $^{24}$Mg(α,α′)$^{24}$Mg...
An efficient neutron detection system with good energy resolution is
needed to characterize decays of neutron-rich nuclei where beta-delayed
neutron emission is a dominant decay mode. Precision neutron
spectroscopy probes nuclear structure effects in neutron-rich nuclei and
is essential to exploit the opportunities in new generation radioactive
beam facilities. A new high-resolution...
SkuTek Instrumentation excels in development of multichannel, high performance digitizers for Nuclear Physics, Particle Physics, and related fields. Our digitizers feature up to 32 channels with low noise and high sampling rates of 100 MSPS @ 14 bits. The data readout is performed individually from each digitizer with a front end 1 G Ethernet connector. The optional back end optical fiber...
Due to the rather scarcity of spectroscopic data on the trans-fermium region, high-spin studies in the few-particles/holes around the Z = 82, N=126 double-shell closure, populating the same high-$j$ orbitals, can provide complementary and crucial information about the single-particle level structure of these nuclei.
A particularly rich phenomenology also arises around the lead double shell...
Inelastic scattering is widely used to determine nuclear structure properties, but can also provide valuable (indirect) information on nuclear reaction cross-sections. Understanding the origin of heavy elements, for example, requires knowledge of neutron capture cross-sections for many exotic isotopes.
In addition to that, nuclear reactions play a key role in modern applications such as...
Properties of proton-emitting nuclei along the $N \sim Z$ line in the vicinity of the proton dripline, can be a useful probe of nuclear structure. In particular, the ground-state spins of the $^{71}$Kr/$^{71}$Br mirror pair have been under debate for several decades driven primarily by the closely spaced (E$_{x}$ = 10 keV) first-excited state in the $^{71}$Br mirror partner [1,2]....
A series of multi-step coulomb excitation experiments were carried out at GDA laboratory of IUAC New Delhi in order to investigate the low-lying electromagnetic nuclear structure of $^{64,68,70}$Zn nuclei, wherein the available information is rather diluted. The reduced transition strength B(E2; $4_{1}^+ \rightarrow 2_{1}^+$) and B(E2; $2_{1}^+ \rightarrow 0_{1}^+$) in few Zn-isotopes shows a...
The $\beta$-decay of $^{125m,125}$Ag into levels in $^{125}$Cd was investigated at the Holifield Radioactive Ion Beam Facility (HRIBF). Uranium-238 targets were bombarded with 50-MeV protons
with an intensity of 15 $\mu$ A, and the induced fission products were mass separated and deposited on a moving tape in the center of the VANDLE array consisting of $\gamma$-detectors and plastic...
A. Wantz, Michigan State University -- Particle identification is a critical task when performing measurements involving rare isotope beams. Invariant mass spectroscopy for the study of neutron-unbound states, the focus of the MoNA Collaboration, requires that the fragments resulting from the decay of the unbound states be accurately identified. These measurements necessitate deconvolving the...
Experimental nuclear physicists are well acquainted with the ubiquitous 1461 keV background $\gamma$ ray from the first-forbidden unique electron-capture decay of $^{40}$K to $^{40}$Ar. The third-forbidden unique beta decay to the $^{40}$Ca ground state is also well known. Not so well known is the third-forbidden unique electron-capture decay channel directly to the $^{40}$Ar ground state....
Experiment S1758 aims to explore the charge dependence of the strong nuclear interaction by probing 55Ni and 55Co near the doubly magic 56Ni. This will be achieved by impinging beams of radioactive 20Na and stable 20Ne upon 40Ca targets to produce 55Ni and 55Co, respectively. Charged particles and γ-rays will be detected by combining the TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer...
We report on new advances in simulation, characterization and fabrication of the $^7$Li-enriched dual neutron-gamma scintillator C$^7$LYC. Detailed GEANT4 simulations have been performed, with specific focus on (n,p) and (n,$\alpha$) reactions on $^{35}$Cl that are primarily responsible for the fast neutron response of C$^7$LYC. The simulations are compared to experimental data to separate...
Machine learning is employed to build an energy density functional for self-bound nuclear systems for the first time. By learning the kinetic energy as a functional of the nucleon density alone, a robust and accurate orbital-free density functional for nuclei is established. Self-consistent calculations that bypass the Kohn-Sham equations provide the ground-state densities, total energies, and...
The nuclear matrix elements of neutrinoless double-beta decay for nuclei 76Ge, 82Se, 100Mo, 130Te, and 150Nd are studied within the triaxial projected shell model, which incorporates simultaneously the triaxial deformation and quasiparticle configuration mixing. The low-lying spectra and the B(E2: 0+ to 2+) values are reproduced well. The effects of the quasiparticles configuration mixing, the...
Mass spectrometry is a versatile and sensitive probe for studying the nuclear structure and decay properties of nuclei. The FRS Ion Catcher at GSI in Germany is a setup for high-accuracy mass spectrometry of projectile fragmentation by using the Multiple-Reflection Time-Of-Flight Mass Spectrometer (MR-TOF-MS) technique. An MR-TOF-MS enables highly accurate, fast and sensitive measurements of...
At the John D. Fox Superconducting Linear Accelerator Laboratory a near-
threshold proton resonance in 11B at Eex = 11.44 ± 0.04 MeV is observed via
the reaction 10Be(d,n)11B →10Be + p in inverse kinematics, measured with a
beam of the radioactive isotope 10Be. The resonance energy at Ec.m. = 211(40)
keV is consistent with a proton signal observed by Ayyad et al. in the β−delayed
proton...
Precision molecular experiments provide a unique tool for measuring electroweak nuclear properties. Compared to atoms, certain molecules can offer more than eleven orders of magnitude enhanced sensitivity to symmetry-violating nuclear effects [Phys. Rev. Lett. 120, 142501], enabling precision tests of the Standard Model. Being able to trap the molecules of interest can significantly enhance...
Measurements of spin observables are critical to understanding the role of spin-orbit, tensor, and nucleon-nucleon interactions. While they are an intrinsic part of scientific programs at worldwide facilities using electromagnetic beams, they are not routine although essential to understanding the structure and reactions of exotic nuclei. The Facility for Rare Isotope Beams (FRIB), which is...
At the 88-inch cyclotron facility of Lawrence Berkeley National Laboratory the nuclear properties of exotic heavy and superheavy elements are studied using the FIONA (for the identification of nuclide $A$) apparatus coupled to the Berkeley Gas-filled Separator (BGS). Actinide and transactinide isotopes created in fusion-evaporation reactions are collected using the BGS and either delivered to...
High fidelity nuclear structure models are of little use if they cannot be computed on modern hardware. This is still the case for medium to heavy mass nuclei of interest to the nuclear physics community. We address the combinatorial growth of shell model dimensions with a novel method for efficient truncation of the Hilbert space. This work is inspired by the density-matrix renormalization...
Deuteron-induced nuclear reactions are typically described within a Faddeev three-body model consisting of a neutron, proton, and the nucleus interacting through pairwise forces. While Faddeev techniques enable the exact description of the three-body dynamics, their predictive power is limited in part by the omission of irreducible three-body nucleon-nucleon-nucleus forces. An alternative...
Extensively explored in both experimental and theoretical studies, the tin isotopes with their closed shell corresponding to the 50 magic proton number continue to provide a fertile ground for studies of both single-particle and collective behaviours of nuclear matter. One recent display of collective
behaviour in the neutron-rich 124Sn74 nucleus is the phenomenon of Pygmy Quadrupole...
The regions around the magic numbers are of interest to both experimental and theoretical nuclear physics, since they serve as benchmarks for understanding nuclear structure, given their configurations. The area around $^{78}$Ni is one such area, and is of particular importance since it has been proposed as a portal to the fifth island of inversion [Nowacki, F. et al. Phys. Rev. Lett. 117,...
Direct fast-timing lifetime measurements were carried out on low-lying states in the semimagic (N = 50) nucleus 94Ru. The experiment was carried out as the first in a series of “FAIR-0” experiments with the DESPEC experimental setup at the Facility for Antiproton and Ion Research (FAIR). Excited states in 94Ru were populated primarily via the β-delayed proton
emission of 95Pd nuclei, produced...
The study of neutron unbound systems via the invariant mass technique is the primary focus of the MoNA Collaboration, which built and operates the MOdular Neutron Array (MoNA) and the Large multi-Institutional Scintillator Array (LISA). Reaction cross-sections for producing neutron unbound systems from radioactive ion beams can be small, 0.1-1mb, and the use of a thick reaction target degrades...
The structure of $^{33}$Mg was investigated by means of two knockout reactions, one-neutron removal from $^{34}$Mg and one-proton removal from $^{34}$Al. Using comparative analysis of the population of observed excited states in the residual $^{33}$Mg, the nature of these states can be deciphered. In addition, the long-standing controversy about the parity of the $^{33}$Mg ground state is...
L. Caceres on behalf of the S3 collaboration
The Super Separator Spectrometer (S3) facility is developed in the framework of the SPIRAL2 project. S3 has been designed to extend the capability of the facility to perform experiments with extremely low cross sections, taking advantage of the very high intensity stable beams of the superconducting linear accelerator of SPIRAL2.
The main areas...
Quadrupole interaction between protons and neutrons drives the nucleus into deformed configurations at low excitation energies. Around the N=50 shell gap, intruder states with spins 1/2$^{+}$ and 5/2$^{+}$, originating from the s$_{1/2}$ and d$_{5/2}$ orbitals were first observed in $^{83}$Se and, later on, in the other N=49 isotones $^{87}$Kr, $^{81}$Ge and $^{79}$Zn. In $^{83}$Se these...
The Extreme Light Infrastructure for Nuclear Physics (ELI-NP) pillar is located in Romania and is intended to serve the broad international scientific community. Its mission covers scientific research involving two domains: the first is laser-driven experiments related to NP, strong-field quantum electrodynamics, and associated vacuum effects.
The other research domain is based on the...
The knockout of nucleons from nuclei is a powerful tool to investigate nuclear structure. It was observed in several occurrences that different final states in a nucleus are populated when produced from one nucleon knockout $(p,2p)$ or from two nucleon knockout $(p,{}3p)$. The understanding of the latter could provide a new tool for nuclear spectroscopy.
Two experimental campaigns conducted...
Ni nuclei, having the magic proton number Z=28, are observed to have spherical shapes near ground state excitation throughout the N=28 to N=40 shell-closure. The experimentally observed low and moderate energy states can be well reproduced by the shell-model calculations involving $\nu$p$_{3/2}$, $\nu$f$_{5/2}$, $\nu$p$_{1/2}$ and $\nu$g$_{9/2}$ orbitals[1,2]. Though the N=40 sub-shell closure...
The neutron and proton mid-shell region, around N = 60 and Z = 40, is renowned for a sudden drop of first 2$^{+}$ state energy in even-even isotopes indicating shape deformation at N = 60 [1-5]. Type Ⅱ shell evolution is suggested to explain the origin of this shape deformation [6, 7] but more experimental data is required to understand this region. In order to figure out the structural...
Lifetimes of low-energy states in $^{211}$At have been measured using the recoil-distance Doppler shift, Doppler-shift attenuation, and fast-timing methods at the University of Cologne. The obtained reduced transition probabilities have been compared to two shell-model calculations, a large-scale shell-model calculation using the Kuo-Herling residual interaction and a calculation using a...
Literature search engines have become an integral and indispensable part of academic research. Search engines like google scholar rely on powerful AI/ML tools to return results that match the user's intended meaning as closely as possible, but they are better suited for general-purpose queries. As a result, they tend to overwhelm the user searching for domain-specific information with...
The β-decay properties of isotopes far from stability, such as β-decay half-lives, β-decay branching ratios, and β-delayed neutron emission probabilities along with detailed level schemes, are necessary to validate nuclear structure models and inform theoretical predictions of the properties of isotopes that are not currently measurable. For nuclei far from stability where β-decay Q-values...
