Fluorine Isotopes Research Articles

Properties of Ground-State of 17,19,20,24,26F using the Wave Functions of Harmonic-Oscillator and Spherical Hankel Functions

The nuclear size radii, density distributions and elastic electron scattering charge form factors for Fluorine isotopes (17,19,20,24,26F) were studied using the radial wave functions (WF) of harmonic-oscillator (HO) potential and free mean field described by spherical Hankel functions (SHF) for the core and the valence parts, respectively for all aforementioned isotopes. The parameters for HO potential (size parameter ) and SHF were chosen to regenerate the available experimental size radii. It was found that using spherical Hankel functions in our work improved the calculated results quantities in comparison with empirical data.

Nuclear structure effects on over-barrier fusion reactions investigated with a new phenomenological model

We investigate the occurrence of nuclear structure effects in the cross section of heavy-ion fusion reactions at energies above the Coulomb barrier. To this end, we initially develop a universal phenomenological model capable to reproduce, with an unprecedented accuracy, all previously published experimental fusion excitation functions with a few parameters. The new model, which foresees exclusively charge, mass, and energy of the colliding systems, shows a clear saturation of the critical angular momentum and avoids analytical non-regularities. The predictions of the newly developed model are then inspected to pin down residual discrepancies with the data, which could be ascribed to the structure of the colliding systems. In this framework, we obtain the following findings: (1) for the first time, we suggest an anomaly in the optimum value of the fusion cross section for systems having nearly-zero fusion Q-values; (2) we point out the occurrence of shell closure effects in the fusion of light systems; (3) we suggest that shell effects are washed-out at relative velocities vrel≳0.07c; (4) in the higher energy part of the fusion excitation function, the cross section for colliding systems involving fluorine or neon isotopes impinging on 2p3/2-1f5/2 nuclei is suppressed, possibly due to the occurrence of α-clustering effects enhancing α-transfer reactions.

Multispectral fluorine-19 MRI enables longitudinal and noninvasive monitoring of tumor-associated macrophages.

High-grade gliomas, the most common and aggressive primary brain tumors, are characterized by a complex tumor microenvironment (TME). Among the immune cells infiltrating the glioma TME, tumor-associated microglia and macrophages (TAMs) constitute the major compartment. In patients with gliomas, increased TAM abundance is associated with more aggressive disease. Alterations in TAM phenotypes and functions have been reported in preclinical models of multiple cancers during tumor development and after therapeutic interventions, including radiotherapy and molecular targeted therapies. These findings indicate that it is crucial to evaluate TAM abundance and dynamics over time. Current techniques to quantify TAMs in patients rely mainly on histological staining of tumor biopsies. Although informative, these techniques require an invasive procedure to harvest the tissue sample and typically only result in a snapshot of a small region at a single point in time. Fluorine isotope 19 MRI (19F MRI) represents a powerful means to noninvasively and longitudinally monitor myeloid cells in pathological conditions by intravenously injecting perfluorocarbon-containing nanoparticles (PFC-NP). In this study, we demonstrated the feasibility and power of 19F MRI in preclinical models of gliomagenesis, breast-to-brain metastasis, and breast cancer and showed that the major cellular source of 19F signal consists of TAMs. Moreover, multispectral 19F MRI with two different PFC-NP allowed us to identify spatially and temporally distinct TAM niches in radiotherapy-recurrent murine gliomas. Together, we have imaged TAMs noninvasively and longitudinally with integrated cellular, spatial, and temporal resolution, thus revealing important biological insights into the critical functions of TAMs, including in disease recurrence.

Density matrix renormalization group description of the island of inversion isotopes F28–33

Recent experiments have confirmed that the neutron-rich isotopes $^{28,29}$F belong to the so-called island of inversion (IOI), a region of the nuclear chart around $Z=10$ and $N=20$ where nuclear structure deviates from the standard shell model predictions due to deformation and continuum effects. However, while the general principles leading to the IOI are relatively well understood, the details of the low-lying structure of the exotic fluorine isotopes $^{28-33}$F are basically unknown. In this work, we perform large-scale shell model calculations including continuum states to investigate the properties of the neutron-rich isotopes $^{25-33}$F, using a core of $^{24}$O and an effective two-body interaction with only three adjustable parameters. We adjust the core potential and interaction on experimentally confirmed states in $^{25,26}$O and $^{25-27}$F and solve the many-body problem using the density matrix renormalization group method for open quantum systems in a $sd$-$fp$ model space. We obtain the first detailed spectroscopy of $^{25-33}$F in the continuum and show how the interplay between continuum effects and deformation explains the recent data on $^{28,29}$F, and produces an inversion of the ${5/2}^+$ and ${1/2}^+$ states in $^{29,31,33}$F. Several deformed one- and two-neutron halo states are predicted in $^{29,31}$F, and we predict the ground state of $^{30}$F to have a structure similar to that of the first ${5/2}^+$ state of $^{29}$F. We also suggest several experimental studies to constraint models and test the present predictions. The complex structure of neutron-rich fluorine isotopes offers a trove of information about the formation of the southern shore of the IOI through a subtle interplay of deformation and continuum couplings driven by the occupation of the quasi-degenerate neutron shells $0d_{3/2}$ and $1p_{3/2}$.

Astrophysical N15(n,γ)N16 reaction rate from precision measurement of the N15(d,p)N16 angular distributions

Background: Asymptotic giant branch stars are one of the possible sites of fluorine production as confirmed by astronomical observation. The $^{15}\mathrm{N}(n,\ensuremath{\gamma})^{16}\mathrm{N}$ reaction competes with $^{15}\mathrm{N}(\ensuremath{\alpha},\ensuremath{\gamma})^{19}\mathrm{F}$ on the reaction chain and thus influences the production of the only stable fluorine isotope $^{19}\mathrm{F}$. The $^{15}\mathrm{N}(n,\ensuremath{\gamma})^{16}\mathrm{N}$ reaction rate at low temperatures of astrophysical interest depends on the neutron spectroscopic factors of the four low-lying states in $^{16}\mathrm{N}$.Purpose: The $^{16}\mathrm{N}$ neutron spectroscopic factors from two previous measurements of $(d,p)$ reaction differ by a factor of $\ensuremath{\approx}2$. This work was intended to investigate these spectroscopic factors via a precision measurement of the $^{15}\mathrm{N}(d,p)^{16}\mathrm{N}$ angular distributions using a Q3D magnetic spectrograph.Methods: The high resolution of the Q3D magnetic spectrograph led to clear separation of these four closely spaced states. The neutron spectroscopic factors were extracted from the present angular distributions with the distorted wave Born approximation and adiabatic distorted wave approximation methods.Results: The neutron spectroscopic factors of the $^{16}\mathrm{N}$ ground, 0.120, 0.298, and 0.397 MeV states were extracted to be $1.32\ifmmode\pm\else\textpm\fi{}0.12, 1.33\ifmmode\pm\else\textpm\fi{}0.18, 1.10\ifmmode\pm\else\textpm\fi{}0.10$, and $1.30\ifmmode\pm\else\textpm\fi{}0.14$, respectively. The new results support the conclusion that these four states in $^{16}\mathrm{N}$ are all good single-particle levels. The cross section and reaction rate of $^{15}\mathrm{N}(n,\ensuremath{\gamma})^{16}\mathrm{N}$ were calculated based on the present spectroscopic factors.Conclusions: The present work provides a precision measurement of the spectroscopic factors of the $^{16}\mathrm{N}$ states and the resulting $^{15}\mathrm{N}(n,\ensuremath{\gamma})^{16}\mathrm{N}$ reaction rate. The present higher reaction rate of the $^{15}\mathrm{N}(n,\ensuremath{\gamma})^{16}\mathrm{N}$ reaction suggests higher flow through $^{15}\mathrm{N}(n,\ensuremath{\gamma})^{16}\mathrm{N}$ compared with previous expectation.

Self-Consistent Study of the Ground State and $$\beta$$-Decay Properties of Oxygen and Fluorine Isotopes

Self-Consistent Study of the Ground State and $$\beta$$-Decay Properties of Oxygen and Fluorine Isotopes

Exploring the halo character and dipole response in the dripline nucleus F31

Lying at the lower edge of the `island of inversion', neutron-rich Fluorine isotopes ($^{29-31}$F) provide a curious case to study the configuration mixing in this part of the nuclear landscape. Recent studies have suggested that a prospective two-neutron halo in the dripline nucleus $^{31}$F could be linked to the occupancy of the $pf$ intruder configurations. Focusing on configuration mixing, matter radii and neutron-neutron ($nn$) correlations in the ground-state of $^{31}$F, we explore various scenarios to analyze its possible halo nature as well as the low-lying electric dipole ($E$1) response within a three-body approach. We use an analytical, transformed harmonic oscillator basis under the aegis of a hyperspherical formalism to construct the ground state three-body wave function of $^{31}$F. The $^{31}$F ground-state configuration mixing and its matter radius are computed for different choices of the $^{30}$F structure coupled to the valence neutron. The admixture of {$p_{3/2}$, $d_{3/2}$, and $f_{7/2}$} components is found to play an important role, favouring the dominance of inverted configurations with dineutron spreads for two-neutron halo formation. The increase in matter radius with respect to the core radius, $\Delta r \geqslant$ 0.30 fm and the dipole distributions along with the integrated $B(E1)$ strengths of $\geqslant$ 2.6 $e^2$fm$^2$ are large enough to be compatible with other two-neutron halo nuclei. Three-body results for $^{31}$F indicate a large spatial extension in its ground state due to the inversion of the energy levels of the normal shell model scheme. The increase is augmented by and is proportional to the extent of the $p_{3/2}$ component in the wave function. Additionally, the enhanced dipole distributions and large $B(E1)$ strengths all point to the two-neutron halo character of $^{31}$F.

Flortaucipir (18F) is a radioactive diagnostic agent indicated for use with positron emission tomography (pet) imaging to image the brain: A review

Flortaucipir F-18, also known as 18F-T807 and 18F-AV-1451, is a small indole molecule synthesized with a radioactive fluorine isotope. It is used as a marker in positron emission tomography (PET) imaging of patients suspected of having Alzheimer's disease. After crossing the blood-brain barrier, flortaucipir F-18 binds to aggregated tau protein, a hallmark of Alzheimer's disease whose incidence correlates well with disease progression. Although flortaucipir F-18 displays low levels of background binding throughout the brain, it does display off-target binding to monoamine oxidase MAO-A and MAO-B, as well as to regions containing high levels of melanin, neuromelanin, and iron It was approved by the FDA on May 28, 2020, for sale by Avid Radiopharmaceuticals under the name TAUVID™ and is the first FDA-approved molecule for imaging aggregated tau protein in the brain[1,2,3].

Radiative neutron capture rate of 19N(n, γ)20N

Low and medium mass neutron rich nuclei have been thought of as important constituents in the final abundance patterns resulting from the r-process reaction network calculations. However, a direct study of these nuclei is extremely difficult and indirect methods like Coulomb dissociation are used for their investigation. We calculate the reaction rate of the 19N(n,γ)20N radiative capture reaction using Coulomb dissociation of the medium mass exotic nucleus 20N, under the aegis of finite range distorted wave Born approximation theory and compare our results with those from the experiment. The reaction rate, when included in the full reaction network, is thought to be crucial to the final abundance of Fluorine isotopes.

Constraints on the neutron drip line with the newly observed Na39

The recently observed weakly-bound 39Na provides a stringent theoretical constraint on the neutron drip-line. We studied the properties of drip-line nuclei around 39Na with the Hartree-Fock-Bogoliubov method and various Skyrme interactions. We adopted the extended SkM*-ext1 parameterization which can properly describe two-neutron separation energies of oxygen and fluorine isotopes and deformations at the center of the "island of inversion". Systematic calculations of drip lines of O, F, Ne, Na, Mg, and Al isotopes have been performed. We infer that 42Mg is weakly bound and 45Al is less weakly bound. 44Mg and 47Al could be barely existed. We also demonstrated the deformed halo properties of 39Na. Our studies could be valuable for experimental explorations of drip-line nuclei in the forthcoming FRIB and other rare-isotope beam facilities .

Neutron drip line of Z= 9–11 isotopic chains * * Partly supported by the National Natural Science Foundation of China (11735003, 11975041, 11775014, 11961141004), the fundamental Research Funds for the Central Universities

A recent experimental breakthrough identified the last bound neutron-rich nuclei in fluorine and neon isotopes. Based on this finding, we perform a theoretical study of Z = 9, 10, 11, 12 isotopes in the relativistic mean field (RMF) model. The mean field parameters are assumed from the PK1 parameterization, and the pairing correlation is described by the particle number conservation BCS (FBCS) method recently formulated in the RMF model. We show that the FBCS approach plays an essential role in reproducing experimental results of fluorine and neon isotopes. Furthermore, we predict 39Na and 40Mg to be the last bound neutron-rich nuclei in sodium and magnesium isotopes.

Ab initio no-core shell model study of and isotopes

In the present work, we have done a comprehensive study of the low-lying energy spectrum for oxygen and fluorine chains using an ab initio no-core shell model. We have used an inside-nonlocal outside-Yukawa (INOY) potential, which is a two-body interaction but also has the effect of three-body forces via short range and nonlocal character. Also, we have performed calculations with N3LO and N2LOopt interactions and compared corresponding results with the experimental data and phenomenological USDB interaction. We have reached up to Nmax = 6 for and F, Nmax = 4 for other oxygen and fluorine isotopes, respectively. We have also discussed the binding energy of oxygen and fluorine chains. Over binding in the ground state (g.s.) energy in neutron rich oxygen isotopes is observed in our largest model space calculations.

Two-neutron halo structure of F31

We apply the Gamow shell model to study $^{25-31}$F isotopes. As both inter-nucleon correlations and continuum coupling are properly treated therein, the structure shape of $^{31}$F at large distance can be analyzed precisely. For this, one-nucleon densities, root-mean square radii and correlation densities are calculated in neutron-rich fluorine isotopes. It is then suggested that $^{31}$F exhibits a two-neutron halo structure, built from both continuum coupling and nucleon-nucleon correlations.

Location of the Neutron Dripline at Fluorine and Neon.

A search for the heaviest isotopes of fluorine, neon, and sodium was conducted by fragmentation of an intense ^{48}Ca beam at 345 MeV/nucleon with a 20-mm-thick beryllium target and identification of isotopes in the large-acceptance separator BigRIPS at the RIKEN Radioactive Isotope Beam Factory. No events were observed for ^{32,33}F, ^{35,36}Ne, and ^{38}Na and only one event for ^{39}Na after extensive running. Comparison with predicted yields excludes the existence of bound states of these unobserved isotopes with high confidence levels. The present work indicates that ^{31}F and ^{34}Ne are the heaviest bound isotopes of fluorine and neon, respectively. The neutron dripline has thus been experimentally confirmed up to neon for the first time since ^{24}O was confirmed to be the dripline nucleus nearly 20years ago. These data provide new keys to understanding the nuclear stability at extremely neutron-rich conditions.

Synthesis of 2-Fluoroacetoacetic Acid and 4-Fluoro-3-hydroxy­butyric Acid

The butyric acid scaffold is the base structure of several human metabolites that serve diverse and prominent biochemical roles including as oxidative sources of cellular energy and as substrates for biosynthesis. Derivatization of metabolites through incorporation of fluorine often alters bioactivity and can facilitate detection and analysis by nuclear magnetic resonance or positron emission tomography depending upon the fluorine isotope employed. We describe the synthesis of two new fluorinated butyric acids (and three related esters) that are derivatives of the metabolites acetoacetic acid and 3-hydroxybutyric acid. 4-Fluoro-3-hydroxybutyric acid is prepared from epoxy ester precursors via ring opening by triethylamine trihydrofluoride. 2-Fluoroacetoacetic acid is prepared by electrophilic fluorination of an acid-labile β-keto ester. The gradual pH-dependent decarboxylation of 2-fluoroacetoacetic acid is investigated by 19F NMR spectroscopy.

Quasi shell gap at 23F

The experimental states of nuclei, close to semi-magic nuclei, having one extra proton on top of closed proton core, in general, connote the arrangement of proton orbitals within a shell. Herein, we have studied the arrangement of proton orbitals (π0d5/2, π1s1/2 and π0d3/2) in sd-shell for Fluorine isotopes within the nuclear shell model framework. The contribution of different components of effective nucleon-nucleon interaction in the evolution of the energies of proton orbitals, and the orbital energy gaps π0d5/2−π1s1/2 and π0d5/2−π0d3/2 at 23,25F has been examined. Results show the evolution of quasi-shell gap at 23F due to key contribution of central force, in particular, of its even-channel, and destructive interference in the contribution of spin–orbit and tensor force. The excitation energies of 121+ and 321+ states of 23F, and 121+ state of 25F are in good agreement with their respective orbital energy gaps. The origin of 321+ state of 25F and its excitation energy has been delineated as an effect of the breakdown of semi-magic core 24O.

Open-shell nuclei from No-Core Shell Model with perturbative improvement

We introduce a hybrid many-body approach that combines the flexibility of the No-Core Shell Model (NCSM) with the efficiency of Multi-Configurational Perturbation Theory (MCPT) to compute ground- and excited-state energies in arbitrary open-shell nuclei in large model spaces. The NCSM in small model spaces is used to define a multi-determinantal reference state that contains the most important multi-particle multi-hole correlations and a subsequent second-order MCPT correction is used to capture additional correlation effects from a large model space. We apply this new ab initio approach for the calculation of ground-state and excitation energies of even and odd-mass carbon, oxygen, and fluorine isotopes and compare to large-scale NCSM calculations that are computationally much more expensive.

Impact Assessment of Phosphogypsum Leachate on Groundwater of Sfax-Agareb (Southeast of Tunisia): Using Geochemical and Isotopic Investigation

The production of phosphoric acid by the Tunisian Chemical Group, in Sfax, Tunisia, led to the degradation of the groundwater quality of the Sfax-Agareb aquifer mainly by the phosphogypsum leachates infiltration. Spatiotemporal monitoring of the quality of groundwater was carried out by performing bimonthly sampling between October 2013 and October 2014. Samples culled in the current study were subject to physicochemical parameters measurements and analysis of the major elements, orthophosphates, fluorine, trace metals, and stable isotopes (18O,2H). The obtained results show that the phosphogypsum leachates infiltration has a major effect on the downstream part of the aquifer, where the highest values of conductivity,SO42-, Ortho-P, andF-, and the lowest pH were recorded. In addition, these results indicated that phosphogypsum leachates contained much higher amount of Cr, Cd, Zn, Cu, Fe, and Al compared to the groundwater. Spatiotemporal variation of the conductivity and concentrations of major elements is linked to the phosphogypsum leachates infiltration as well as to a wide range of factors such as the natural conditions of feeding and the water residence time. Contents ofO18and2H showed that the water of the Sfax-Agareb aquifer undergoes a large scale evaporation process originated from recent rainfall.

The 19F(α, p)22Ne and 23Na(p,α)20Ne reaction in AGB nucleosynthesis via THM

In AGB environment, fluorine and sodium abundances are still matter of debate. About 19F (only stable isotope of fluorine), its abundance in the universe is strictly related to standard and extra-mixing processes taking place inside AGB-stars, that are considered to be the most important sites for its production. Nevertheless the way in which it is destroyed is far from being well understood. On the other hand, 23Na presence in Globular Clusters, along with is well-known anticorrelation with oxygen has made clear that this element must be produced in previous generations stars, and intermediatemass AGB stars are one of the possible candidates for its production. For this reason we studied the 19F(α,p)22Ne and 23Na(p,α)20Ne reactions in the energy range of relevance for astrophysics via the Trojan Horse Method (THM), using the three-body reactions 6Li(19F, p22Ne)d and 23Na(d, pn)20Ne.

Low- Z shore of the “island of inversion” and the reduced neutron magicity toward O28

The two odd-even fluorine isotopes $^{27,29}\mathrm{F}$ were studied via in-beam $\ensuremath{\gamma}$-ray spectroscopy at the RIKEN Radioactive Isotope Beam Factory. A secondary beam of $^{30}\mathrm{Ne}$ was used to induce one-proton and one-proton--two-neutron removal reactions on carbon and polyethylene targets at midtarget energies of 228 MeV/$u$. Excited states were observed at 915(12) keV for $^{27}\mathrm{F}$ and at 1080(18) keV for $^{29}\mathrm{F}$. Both were assigned a $1/{2}_{1}^{+}$ spin and parity. The low transition energy for $^{29}\mathrm{F}$ largely disagrees with shell model predictions restricted to the $sd$ model space. Calculations using effective interactions that include the neutron $pf$ shell indicate that the $N=20$ gap is quenched for $^{29}\mathrm{F}$, thus extending the ``island of inversion'' to isotopes with proton number $Z=9$. Variations of the $N=20$ gap further reveal a strong correlation to the $1/{2}_{1}^{+}$ level energy in $^{29}\mathrm{F}$ and suggest a persistent reduced neutron gap for $^{28}\mathrm{O}$.